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AAPS PharmSciTech     Hybrid Journal   (Followers: 6)
Acetic Acid Bacteria     Open Access   (Followers: 1)
ACS Central Science     Open Access   (Followers: 5)
ACS Chemical Biology     Full-text available via subscription   (Followers: 192)
ACS Chemical Neuroscience     Full-text available via subscription   (Followers: 15)
Acta Crystallographica Section D : Biological Crystallography     Hybrid Journal   (Followers: 10)
Acta Crystallographica Section F: Structural Biology Communications     Hybrid Journal   (Followers: 7)
Advances and Applications in Bioinformatics and Chemistry     Open Access   (Followers: 9)
Advances in Biological Chemistry     Open Access   (Followers: 7)
Advances in Carbohydrate Chemistry and Biochemistry     Full-text available via subscription   (Followers: 9)
Advances in Plant Biochemistry and Molecular Biology     Full-text available via subscription   (Followers: 7)
Advances in Protein Chemistry and Structural Biology     Full-text available via subscription   (Followers: 15)
African Journal of Biochemistry Research     Open Access   (Followers: 1)
African Journal of Chemical Education     Open Access   (Followers: 2)
Alkaloids: Chemical and Biological Perspectives     Full-text available via subscription   (Followers: 3)
American Journal of Biochemistry     Open Access   (Followers: 7)
American Journal of Biochemistry and Biotechnology     Open Access   (Followers: 62)
American Journal of Biochemistry and Molecular Biology     Open Access   (Followers: 13)
American Journal of Polymer Science     Open Access   (Followers: 23)
Amino Acids     Hybrid Journal   (Followers: 8)
Analytical Biochemistry     Hybrid Journal   (Followers: 142)
Angiogenesis     Hybrid Journal   (Followers: 3)
Annals of Clinical Biochemistry     Hybrid Journal   (Followers: 8)
Annual Review of Biochemistry     Full-text available via subscription   (Followers: 51)
Annual Review of Chemical and Biomolecular Engineering     Full-text available via subscription   (Followers: 10)
Applied Biochemistry and Biotechnology     Hybrid Journal   (Followers: 44)
Applied Biochemistry and Microbiology     Hybrid Journal   (Followers: 16)
Applied Organometallic Chemistry     Hybrid Journal   (Followers: 5)
Archives of Biochemistry and Biophysics     Hybrid Journal   (Followers: 22)
Archives of Insect Biochemistry and Physiology     Hybrid Journal  
Archives Of Physiology And Biochemistry     Hybrid Journal   (Followers: 1)
Asian Journal of Biochemistry     Open Access   (Followers: 1)
Avicenna Journal of Medical Biochemistry     Open Access  
Bangladesh Journal of Medical Biochemistry     Open Access   (Followers: 2)
BBA Clinical     Open Access  
BBR : Biochemistry and Biotechnology Reports     Open Access   (Followers: 4)
Biocatalysis     Open Access  
Biochemical and Biophysical Research Communications     Hybrid Journal   (Followers: 19)
Biochemical and Molecular Medicine     Full-text available via subscription   (Followers: 4)
Biochemical Compounds     Open Access  
Biochemical Engineering Journal     Hybrid Journal   (Followers: 14)
Biochemical Genetics     Hybrid Journal   (Followers: 3)
Biochemical Journal     Full-text available via subscription   (Followers: 26)
Biochemical Pharmacology     Hybrid Journal   (Followers: 8)
Biochemical Society Transactions     Full-text available via subscription   (Followers: 4)
Biochemical Systematics and Ecology     Hybrid Journal   (Followers: 3)
Biochemistry     Full-text available via subscription   (Followers: 240)
Biochemistry & Pharmacology : Open Access     Open Access   (Followers: 3)
Biochemistry & Physiology : Open Access     Open Access  
Biochemistry (Moscow)     Hybrid Journal   (Followers: 4)
Biochemistry (Moscow) Supplement Series A: Membrane and Cell Biology     Hybrid Journal   (Followers: 3)
Biochemistry (Moscow) Supplemental Series B: Biomedical Chemistry     Hybrid Journal   (Followers: 3)
Biochemistry and Biophysics Reports     Open Access  
Biochemistry and Cell Biology     Full-text available via subscription   (Followers: 15)
Biochemistry and Molecular Biology Education     Hybrid Journal   (Followers: 5)
Biochemistry and Molecular Biology of Fishes     Full-text available via subscription   (Followers: 1)
Biochemistry Research International     Open Access   (Followers: 5)
Biochimica et Biophysica Acta (BBA) - Molecular and Cell Biology of Lipids     Hybrid Journal   (Followers: 9)
Biochimica et Biophysica Acta (BBA) - Molecular Basis of Disease     Hybrid Journal   (Followers: 16)
Biochimica et Biophysica Acta (BBA) - Molecular Cell Research     Hybrid Journal   (Followers: 7)
Biochimie     Hybrid Journal   (Followers: 6)
Biochimie Open     Open Access  
Bioconjugate Chemistry     Full-text available via subscription   (Followers: 30)
BioDrugs     Full-text available via subscription   (Followers: 8)
Bioelectrochemistry     Hybrid Journal   (Followers: 1)
Biofuels     Hybrid Journal   (Followers: 10)
Biogeochemistry     Hybrid Journal   (Followers: 11)
BioInorganic Reaction Mechanisms     Hybrid Journal   (Followers: 1)
Biokemistri     Open Access  
Biological Chemistry     Partially Free   (Followers: 25)
Biomaterials Research     Open Access   (Followers: 4)
Biomedicines     Open Access   (Followers: 1)
BioMolecular Concepts     Hybrid Journal   (Followers: 2)
Bioscience, Biotechnology, and Biochemistry     Hybrid Journal   (Followers: 25)
Biosimilars     Open Access   (Followers: 1)
Biotechnology and Applied Biochemistry     Hybrid Journal   (Followers: 45)
Bitácora Digital     Open Access  
BMC Biochemistry     Open Access   (Followers: 14)
Bulletin of University of Agricultural Sciences and Veterinary Medicine Cluj-Napoca : Food Science and Technology     Open Access  
Carbohydrate Polymers     Hybrid Journal   (Followers: 7)
Cell Biochemistry and Biophysics     Hybrid Journal   (Followers: 5)
Cell Biochemistry and Function     Hybrid Journal   (Followers: 4)
Cellular Physiology and Biochemistry     Open Access   (Followers: 3)
ChemBioChem     Hybrid Journal   (Followers: 6)
Chemical and Biological Technologies for Agriculture     Open Access  
Chemical Biology & Drug Design     Hybrid Journal   (Followers: 22)
Chemical Engineering Journal     Hybrid Journal   (Followers: 30)
Chemical Senses     Hybrid Journal   (Followers: 1)
Chemical Speciation and Bioavailability     Open Access   (Followers: 1)
Chemico-Biological Interactions     Hybrid Journal   (Followers: 3)
Chemistry & Biodiversity     Hybrid Journal   (Followers: 5)
Chemistry & Biology     Full-text available via subscription   (Followers: 29)
Chemistry and Ecology     Hybrid Journal  
ChemTexts     Hybrid Journal  
Clinica Chimica Acta     Hybrid Journal   (Followers: 36)
Clinical Biochemist Reviews     Full-text available via subscription   (Followers: 1)
Clinical Biochemistry     Hybrid Journal   (Followers: 19)
Clinical Chemistry     Full-text available via subscription   (Followers: 67)
Clinical Chemistry and Laboratory Medicine     Hybrid Journal   (Followers: 61)
Clinical Lipidology     Full-text available via subscription  
Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology     Hybrid Journal   (Followers: 5)
Comparative Biochemistry and Physiology Part B: Biochemistry and Molecular Biology     Hybrid Journal   (Followers: 2)
Comparative Biochemistry and Physiology Part C: Toxicology & Pharmacology     Hybrid Journal   (Followers: 7)
Comparative Biochemistry and Physiology Part D: Genomics and Proteomics     Hybrid Journal   (Followers: 3)
Comprehensive Biochemistry     Full-text available via subscription   (Followers: 1)
Computational Biology and Chemistry     Hybrid Journal   (Followers: 10)
Critical Reviews in Biochemistry and Molecular Biology     Hybrid Journal   (Followers: 5)
Current Chemical Biology     Hybrid Journal   (Followers: 2)
Current Medicinal Chemistry     Hybrid Journal   (Followers: 14)
Current Opinion in Chemical Biology     Hybrid Journal   (Followers: 24)
Current Opinion in Lipidology     Hybrid Journal   (Followers: 5)
DNA Barcodes     Open Access  
Doklady Biochemistry and Biophysics     Hybrid Journal   (Followers: 1)
Doklady Chemistry     Hybrid Journal  
Egyptian Journal of Biochemistry and Molecular Biology     Full-text available via subscription  
FABICIB     Open Access  
FEBS Letters     Hybrid Journal   (Followers: 59)
FEBS Open Bio     Open Access   (Followers: 3)
Fish Physiology and Biochemistry     Hybrid Journal   (Followers: 4)
Food & Function     Full-text available via subscription   (Followers: 5)
Foundations of Modern Biochemistry     Full-text available via subscription  
Free Radicals and Antioxidants     Full-text available via subscription   (Followers: 3)
Frontiers in Molecular Biosciences     Open Access   (Followers: 2)
Frontiers in Natural Product Chemistry     Hybrid Journal  
Global Biogeochemical Cycles     Full-text available via subscription   (Followers: 12)
Green Chemistry     Full-text available via subscription   (Followers: 9)
Histochemistry and Cell Biology     Hybrid Journal   (Followers: 4)
Indian Journal of Biochemistry and Biophysics (IJBB)     Open Access   (Followers: 3)
Indian Journal of Clinical Biochemistry     Hybrid Journal   (Followers: 1)
Indonesian Biomedical Journal     Open Access  
Insect Biochemistry and Molecular Biology     Hybrid Journal   (Followers: 3)
International Journal of Biochemistry & Cell Biology     Hybrid Journal   (Followers: 7)
International Journal of Biochemistry and Biophysics     Open Access   (Followers: 1)
International Journal of Biological Chemistry     Open Access   (Followers: 4)
International Journal of Biomedical Nanoscience and Nanotechnology     Hybrid Journal   (Followers: 6)
International Journal of Food Contamination     Open Access  
International Journal of Plant Physiology and Biochemistry     Open Access  
International Journal of Plant Research     Open Access   (Followers: 3)
International Journal of Secondary Metabolite     Open Access   (Followers: 1)
Invertebrate Immunity     Open Access   (Followers: 1)
JBIC Journal of Biological Inorganic Chemistry     Hybrid Journal   (Followers: 5)
Journal of Microbial & Biochemical Technology     Open Access   (Followers: 1)
Journal of Applied Biology & Biotechnology     Open Access   (Followers: 1)
Journal of Bioactive and Compatible Polymers     Hybrid Journal   (Followers: 2)
Journal of Biochemistry     Hybrid Journal   (Followers: 43)
Journal of Biological Chemistry     Full-text available via subscription   (Followers: 177)
Journal of Biomaterials Science, Polymer Edition     Hybrid Journal   (Followers: 9)
Journal of Carbohydrate Chemistry     Hybrid Journal   (Followers: 7)
Journal of Cellular Biochemistry     Hybrid Journal   (Followers: 5)
Journal of Chemical Biology     Hybrid Journal   (Followers: 1)
Journal of Chemical Neuroanatomy     Hybrid Journal  
Journal of Clinical Lipidology     Hybrid Journal   (Followers: 1)
Journal of Comparative Physiology B : Biochemical, Systemic, and Environmental Physiology     Hybrid Journal   (Followers: 4)
Journal of Drug Discovery and Therapeutics     Open Access   (Followers: 1)
Journal of Enzyme Inhibition and Medicinal Chemistry     Hybrid Journal   (Followers: 4)
Journal of Evolutionary Biochemistry and Physiology     Hybrid Journal  
Journal of Food and Drug Analysis     Open Access  
Journal of Forensic Toxicology and Pharmacology     Hybrid Journal   (Followers: 3)
Journal of Inborn Errors of Metabolism and Screening     Open Access  
Journal of Inorganic Biochemistry     Hybrid Journal   (Followers: 5)
Journal of Investigational Biochemistry     Open Access   (Followers: 2)
Journal of Medical and Biomedical Sciences     Open Access  
Journal of Medical Biochemistry     Open Access   (Followers: 4)
Journal of Medicine and Biomedical Research     Open Access   (Followers: 1)
Journal of Molecular Biochemistry     Open Access   (Followers: 3)
Journal of Molecular Diagnostics     Hybrid Journal   (Followers: 6)
Journal of Neurochemistry     Hybrid Journal   (Followers: 3)
Journal of Nutritional Biochemistry     Hybrid Journal   (Followers: 7)
Journal of Pediatric Biochemistry     Hybrid Journal   (Followers: 1)
Journal of Peptide Science     Hybrid Journal   (Followers: 23)
Journal of Photochemistry and Photobiology B: Biology     Hybrid Journal   (Followers: 3)
Journal of Physiobiochemical Metabolism     Hybrid Journal   (Followers: 1)
Journal of Physiology and Biochemistry     Hybrid Journal   (Followers: 3)
Journal of Plant Biochemistry and Biotechnology     Hybrid Journal   (Followers: 5)
Journal of Steroid Biochemistry and Molecular Biology     Hybrid Journal   (Followers: 2)
Journal of Virology & Antiviral Research     Hybrid Journal   (Followers: 3)
Journal of Wood Chemistry and Technology     Hybrid Journal   (Followers: 7)
La Rivista Italiana della Medicina di Laboratorio - Italian Journal of Laboratory Medicine     Hybrid Journal  
Lab on a Chip     Full-text available via subscription   (Followers: 34)
Marine Chemistry     Hybrid Journal   (Followers: 6)
Methods in Enzymology     Full-text available via subscription   (Followers: 11)
Molecular and Biochemical Parasitology     Hybrid Journal   (Followers: 2)
Molecular and Cellular Biochemistry     Hybrid Journal   (Followers: 4)
Molecular Aspects of Medicine     Hybrid Journal   (Followers: 5)
Molecular Informatics     Hybrid Journal   (Followers: 4)
Molecular inhibitors in targeted therapy     Open Access  
Moscow University Chemistry Bulletin     Hybrid Journal   (Followers: 1)
Mycology : An International Journal on Fungal Biology     Hybrid Journal   (Followers: 5)
Natural Products and Bioprospecting     Open Access   (Followers: 3)
Nature Chemical Biology     Full-text available via subscription   (Followers: 69)
Nature Communications     Open Access   (Followers: 123)
Neurosignals     Open Access  
Novelty in Biomedicine     Open Access  
Ocean Acidification     Open Access   (Followers: 3)
Organic & Biomolecular Chemistry     Full-text available via subscription   (Followers: 87)
Peptidomics     Open Access  
Pesticide Biochemistry and Physiology     Hybrid Journal   (Followers: 4)
Pflugers Archiv European Journal of Physiology     Hybrid Journal   (Followers: 3)
Pharmaceutical Bioprocessing     Full-text available via subscription   (Followers: 1)
Pharmacognosy Magazine     Open Access   (Followers: 2)

        1 2     

Journal Cover Insect Biochemistry and Molecular Biology
  [SJR: 1.957]   [H-I: 86]   [3 followers]  Follow
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 0965-1748
   Published by Elsevier Homepage  [3038 journals]
  • Toxicity of Cry1A toxins from Bacillus thuringiensis to CF1 cells does not
           involve activation of adenylate cyclase/PKA signaling pathway
    • Authors: Leivi Portugal; Carlos Muñóz-Garay; Diana L. Martínez de Castro; Mario Soberón; Alejandra Bravo
      Pages: 21 - 31
      Abstract: Publication date: January 2017
      Source:Insect Biochemistry and Molecular Biology, Volume 80
      Author(s): Leivi Portugal, Carlos Muñóz-Garay, Diana L. Martínez de Castro, Mario Soberón, Alejandra Bravo
      Bacillus thuringiensis (Bt) bacteria produce Cry toxins that are able to kill insect pests. Different models explaining the mode of action of these toxins have been proposed. The pore formation model proposes that the toxin creates pores in the membrane of the larval midgut cells after interaction with different receptors such as cadherin, aminopeptidase N and alkaline phosphatase and that this pore formation activity is responsible for the toxicity of these proteins. The alternative model proposes that interaction with cadherin receptor triggers an intracellular cascade response involving protein G, adenylate cyclase (AC) and protein kinase A (PKA). In addition, it was shown that Cry toxins induce a defense response in the larvae involving the activation of mitogen-activated kinases such as MAPK p38 in different insect orders. Here we analyzed the mechanism of action of Cry1Ab and Cry1Ac toxins and a collection of mutants from these toxins in the insect cell line CF1 from Choristoneura fumiferana, that is naturally sensitive to these toxins. Our results show that both toxins induced permeability of K+ ions into the cells. The initial response after intoxication with Cry1Ab and Cry1Ac toxins involves the activation of a defense response that involves the phosphorylation of MAPK p38. Analysis of activation of PKA and AC activities indicated that the signal transduction involving PKA, AC and cAMP was not activated during Cry1Ab or Cry1Ac intoxication. In contrast we show that Cry1Ab and Cry1Ac activate apoptosis. These data indicate that Cry toxins can induce an apoptotic death response not related with AC/PKA activation. Since Cry1Ab and Cry1Ac toxins affected K+ ion permeability into the cells, and that mutant toxins affected in pore formation are not toxic to CF1, we propose that pore formation activity of the toxins is responsible of triggering cell death response in CF1cells.
      Graphical abstract image

      PubDate: 2016-11-23T17:04:24Z
      DOI: 10.1016/j.ibmb.2016.11.004
      Issue No: Vol. 80 (2016)
  • Differential gene expression underlying ovarian phenotype determination in
           honey bee, Apis mellifera L, caste development
    • Authors: Denyse Cavalcante Lago; Fernanda Carvalho Humann; Angel Roberto Barchuk; Kuruvilla Joseph Abraham; Klaus Hartfelder
      Pages: 1 - 12
      Abstract: Publication date: Available online 5 October 2016
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Denyse Cavalcante Lago, Fernanda Carvalho Humann, Angel Roberto Barchuk, Kuruvilla Joseph Abraham, Klaus Hartfelder
      Adult honey bee queens and workers drastically differ in ovary size. This adult ovary phenotype difference becomes established during the final larval instars, when massive programmed cell death leads to the degeneration of 95–99% of the ovariole anlagen in workers. The higher juvenile hormone (JH) levels in queen larvae protect the ovaries against such degeneration. To gain insights into the molecular architecture underlying this divergence critical for adult caste fate and worker sterility, we performed a microarray analysis on fourth and early fifth instar queen and worker ovaries. For the fourth instar we found nine differentially expressed genes (DEGs) with log2FC > 1.0, but this number increased to 56 in early fifth-instar ovaries. We selected 15 DEGs for quantitative PCR (RT-qPCR) analysis. Nine differed significantly by the variables caste and/or development. Interestingly, genes with enzyme functions were higher expressed in workers, while those related to transcription and signaling had higher transcript levels in queens. For the RT-qPCR confirmed genes we analyzed their response to JH. This revealed a significant up-regulation for two genes, a short chain dehydrogenase reductase (sdr) and a heat shock protein 90 (hsp90). Five other genes, including hsp60 and hexamerin 70b (hex70b), were significantly down-regulated by JH. The sdr gene had previously come up as differentially expressed in other transcriptome analyses on honey bee larvae and heat shock proteins are frequently involved in insect hormone responses, this making them interesting candidates for further functional assays.
      Graphical abstract image

      PubDate: 2016-10-08T01:20:57Z
      DOI: 10.1016/j.ibmb.2016.10.001
      Issue No: Vol. 79 (2016)
  • Sperm-less males modulate female behaviour in Ceratitis capitata (Diptera:
    • Authors: Paolo Gabrieli; Francesca Scolari; Alessandro Di Cosimo; Grazia Savini; Marco Fumagalli; Ludvik M. Gomulski; Anna R. Malacrida; Giuliano Gasperi
      Pages: 13 - 26
      Abstract: Publication date: Available online 6 October 2016
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Paolo Gabrieli, Francesca Scolari, Alessandro Di Cosimo, Grazia Savini, Marco Fumagalli, Ludvik M. Gomulski, Anna R. Malacrida, Giuliano Gasperi
      In the Mediterranean fruit fly, Ceratitis capitata (Wiedemann)(Diptera: Tephritidae), mating has a strong impact on female biology, leading to a decrease in sexual receptivity and increased oviposition and fecundity. Previous studies suggest that sperm transfer may play a role in inducing these behavioural changes. Here we report the identification of a medfly innexin gene, Cc-inx5, whose expression is limited to the germ-line of both sexes. Through RNA interference of this gene, we generated males without testes and, consequently, sperm, but apparently retaining all the other reproductive organs intact. These sperm-less males were able to mate and, like their wild-type counterparts, to induce in their partners increased oviposition rates and refractoriness to remating. Interestingly, matings to sperm-less males results in oviposition rates higher than those induced by copulation with control males. In addition, the observed female post-mating behavioural changes were congruent with changes in transcript abundance of genes known to be regulated by mating in this species. Our results suggest that sperm transfer is not necessary to reduce female sexual receptivity and to increase oviposition and fecundity. These data pave the way to a better understanding of the role/s of seminal components in modulating female post-mating responses. In the long term, this knowledge will be the basis for the development of novel approaches for the manipulation of female fertility, and, consequently, innovative tools to be applied to medfly control strategies in the field.
      Graphical abstract image

      PubDate: 2016-10-08T01:20:57Z
      DOI: 10.1016/j.ibmb.2016.10.002
      Issue No: Vol. 79 (2016)
  • IPPA08 allosterically enhances the action of imidacloprid on nicotinic
           acetylcholine receptors
    • Authors: Haibo Bao; Xusheng Shao; Yixi Zhang; Jiagao Cheng; Yunchao Wang; Xiaoyong Xu; Jichao Fang; Zewen Liu; Zhong Li
      Pages: 36 - 41
      Abstract: Publication date: December 2016
      Source:Insect Biochemistry and Molecular Biology, Volume 79
      Author(s): Haibo Bao, Xusheng Shao, Yixi Zhang, Jiagao Cheng, Yunchao Wang, Xiaoyong Xu, Jichao Fang, Zewen Liu, Zhong Li
      Our previous study showed that IPPA08, a cis-configuration neonicotinoid compound with unique oxabridged substructure, acted as a specific synergist to neonicotinoid insecticides targeting nicotinic acetylcholine receptors (nAChRs). Heteropentamer nAChRs have diverse characteristics and can form canonical and noncanonical subunit interfaces. While canonical interfaces have been exploited as targets of many drugs, noncanonical interfaces have received less attention. In this study, the mechanism of IPPA08 synergism was evaluated on hybrid nAChRs consisting of three α1 subunits from the brown planthopper and two rat β1 subunits (Nlα1/rβ2) expressed in Xenopus oocytes. IPPA08 alone evoked inward currents, but only at very high concentrations, greater than 1 mM. However, at concentrations below 200 μM, IPPA08 slowed the decay of inward currents evoked by imidacloprid, but not by acetylcholine, and also increased the sensitivity of Nlα1/rβ2 to imidacloprid. Both modulations by IPPA08 were concentration-dependent in the same concentration range of 10–150 μM. Experimentally induced mutations in canonical (α+/β−) and noncanonical (β+/α−) interfaces of Nlα1/rβ2 receptors were also examined to evaluate the presence of possible binding sites for IPPA08 on the receptors. Our results showed that mutations in the canonical interfaces affected only the potency of IPPA08 as an agonist, while mutations in the noncanonical interfaces affected only the synergistic action of IPPA08. Based on these results, we propose that at low concentrations IPPA08 can act as a positive allosteric modulator of noncanonical interfaces, and likely slow the decay of currents through stabilizing the open-channel state caused by the action of imidacloprid on canonical interfaces.
      Graphical abstract image

      PubDate: 2016-11-02T15:10:10Z
      DOI: 10.1016/j.ibmb.2016.10.010
      Issue No: Vol. 79 (2016)
  • Differential proteomics reveals novel insights into Nosema–honey bee
    • Authors: Christoph Kurze; Ryan Dosselli; Julia Grassl; Yves Le Conte; Per Kryger; Boris Baer; Robin F.A. Moritz
      Pages: 42 - 49
      Abstract: Publication date: December 2016
      Source:Insect Biochemistry and Molecular Biology, Volume 79
      Author(s): Christoph Kurze, Ryan Dosselli, Julia Grassl, Yves Le Conte, Per Kryger, Boris Baer, Robin F.A. Moritz
      Host manipulation is a common strategy by parasites to reduce host defense responses, enhance development, host exploitation, reproduction and, ultimately, transmission success. As these parasitic modifications can reduce host fitness, increased selection pressure may result in reciprocal adaptations of the host. Whereas the majority of studies on host manipulation have explored resistance against parasites (i.e. ability to prevent or limit an infection), data describing tolerance mechanisms (i.e. ability to limit harm of an infection) are scarce. By comparing differential protein abundance, we provide evidence of host-parasite interactions in the midgut proteomes of N. ceranae-infected and uninfected honey bees from both Nosema-tolerant and Nosema-sensitive lineages. We identified 16 proteins out of 661 protein spots that were differentially abundant between experimental groups. In general, infections of Nosema resulted in an up-regulation of the bee's energy metabolism. Additionally, we identified 8 proteins that were differentially abundant between tolerant and sensitive honey bees regardless of the Nosema infection. Those proteins were linked to metabolism, response to oxidative stress and apoptosis. In addition to bee proteins, we also identified 3 Nosema ceranae proteins. Interestingly, abundance of two of these Nosema proteins were significantly higher in infected Nosema-sensitive honeybees relative to the infected Nosema-tolerant lineage. This may provide a novel candidate for studying the molecular interplay between N. ceranae and its honey bee host in more detail.
      Graphical abstract image

      PubDate: 2016-11-02T15:10:10Z
      DOI: 10.1016/j.ibmb.2016.10.005
      Issue No: Vol. 79 (2016)
  • Metabolic imidacloprid resistance in the brown planthopper, Nilaparvata
           lugens, relies on multiple P450 enzymes
    • Authors: Yixi Zhang; Yuanxue Yang; Huahua Sun; Zewen Liu
      Pages: 50 - 56
      Abstract: Publication date: December 2016
      Source:Insect Biochemistry and Molecular Biology, Volume 79
      Author(s): Yixi Zhang, Yuanxue Yang, Huahua Sun, Zewen Liu
      Target insensitivity contributing to imidacloprid resistance in Nilaparvata lugens has been reported to occur either through point mutations or quantitative change in nicotinic acetylcholine receptors (nAChRs). However, the metabolic resistance, especially the enhanced detoxification by P450 enzymes, is the major mechanism in fields. From one field-originated N. lugens population, an imidacloprid resistant strain G25 and a susceptible counterpart S25 were obtained to analyze putative roles of P450s in imidacloprid resistance. Compared to S25, over-expression of twelve P450 genes was observed in G25, with ratios above 5.0-fold for CYP6AY1, CYP6ER1, CYP6CS1, CYP6CW1, CYP4CE1 and CYP425B1. RNAi against these genes in vivo and recombinant tests on the corresponding proteins in vitro revealed that four P450s, CYP6AY1, CYP6ER1, CYP4CE1 and CYP6CW1, played important roles in imidacloprid resistance. The importance of the four P450s was not equal at different stages of resistance development based on their over-expression levels, among which CYP6ER1 was important at all stages, and that the others might only contribute at certain stages. The results indicated that, to completely reflect roles of P450s in insecticide resistances, their over-expression in resistant individuals, expression changes at the stages of resistance development, and catalytic activities against insecticides should be considered. In this study, multiple P450s, CYP6AY1, CYP6ER1, CYP4CE1 and CYP6CW1, have proven to be important in imidacloprid resistance.
      Graphical abstract image

      PubDate: 2016-11-02T15:10:10Z
      DOI: 10.1016/j.ibmb.2016.10.009
      Issue No: Vol. 79 (2016)
  • miR-276 and miR-3016-modulated expression of acetyl-CoA carboxylase
           accounts for spirotetramat resistance in Aphis gossypii Glover
    • Authors: Xiang Wei; Chao Zheng; Tianfei Peng; Yiou Pan; Jinghui Xi; Xuewei Chen; Juhong Zhang; Shuang Yang; Xiwu Gao; Qingli Shang
      Pages: 57 - 65
      Abstract: Publication date: Available online 27 October 2016
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Xiang Wei, Chao Zheng, Tianfei Peng, Yiou Pan, Jinghui Xi, Xuewei Chen, Juhong Zhang, Shuang Yang, Xiwu Gao, Qingli Shang
      Acetyl-coenzyme A carboxylase (acetyl-CoA carboxylase, ACC) catalyses the carboxylation of acetyl-CoA to produce malonyl-CoA during de novo fatty acid synthesis. A laboratory-selected spirotetramat-resistant strain (SR) of cotton aphid was used in this study. RT-qPCR results demonstrated significant increases in the levels of ACC transcript in the resistant strain compared to the susceptible strain. Depletion of overexpressed ACC transcripts by RNAi also significantly enhanced the sensitivity of the resistant aphid to spirotetramat. We hypothesized that ACC gene expression is subject to post-transcriptional regulation. To investigate the underlying mechanism, the 66 known miRNAs of Aphis gossypii were used for target prediction, eight of which were predicted to target ACC. Validation identified two miRNAs, miR-276 and miR-3016, with abundance levels that were highly inversely correlated with ACC transcript levels. This result suggests that the miRNAs miR-276 and miR-3016 may play major roles in the post-transcriptional regulation of the ACC gene. Modulation of the abundance of miR-276 and miR-3016 through addition of inhibitors/mimics of miR-276 or miR-3016 to the artificial diet significantly altered both ACC transcript levels and the tolerance of A. gossypii to spirotetramat, thus confirming the roles of these two miRNAs in the regulation of spirotetramat resistance.
      Graphical abstract image

      PubDate: 2016-11-02T15:10:10Z
      DOI: 10.1016/j.ibmb.2016.10.011
      Issue No: Vol. 79 (2016)
  • A broadly tuned odorant receptor in neurons of trichoid sensilla in
           locust, Locusta migratoria
    • Authors: Yinwei You; Dean P. Smith; Mingyue Lv; Long Zhang
      Pages: 66 - 72
      Abstract: Publication date: Available online 27 October 2016
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Yinwei You, Dean P. Smith, Mingyue Lv, Long Zhang
      Insects have evolved sophisticated olfactory reception systems to sense exogenous chemical signals. Odorant receptors (ORs) on the membrane of chemosensory neurons are believed to be key molecules in sensing exogenous chemical cues. ORs in different species of insects are diverse and should tune a species to its own specific semiochemicals relevant to their survival. The orthopteran insect, locust (Locusta migratoria), is a model hemimetabolous insect. There is very limited knowledge on the functions of locust ORs although many locust OR genes have been identified in genomic sequencing experiments. In this paper, a locust OR, LmigOR3 was localized to neurons housed in trichoid sensilla by in situ hybridization. LmigOR3 was expressed as a transgene in Drosophila trichoid olfactory neurons (aT1) lacking the endogenous receptor Or67d and the olfactory tuning curve and dose-response curves were established for this locust receptor. The results show that LmigOR3 sensitizes neurons to ketones, esters and heterocyclic compounds, indicating that LmigOR3 is a broadly tuned receptor. LmigOR3 is the first odorant receptor from Orthoptera that has been functionally analyzed in the Drosophila aT1 system. This work demonstrates the utility of the Drosophila aT1 system for functional analysis of locust odorant receptors and suggests that LmigOR3 may be involved in detecting food odorants, or perhaps locust body volatiles that may help us to develop new control methods for locusts.
      Graphical abstract image

      PubDate: 2016-11-02T15:10:10Z
      DOI: 10.1016/j.ibmb.2016.10.008
      Issue No: Vol. 79 (2016)
  • The steroid hormone 20-hydroxyecdysone promotes switching from autophagy
           to apoptosis by increasing intracellular calcium levels
    • Authors: Yong-Bo Li; Xiang-Ru Li; Ting Yang; Jin-Xing Wang; Xiao-Fan Zhao
      Pages: 73 - 86
      Abstract: Publication date: Available online 21 October 2016
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Yong-Bo Li, Xiang-Ru Li, Ting Yang, Jin-Xing Wang, Xiao-Fan Zhao
      Autophagy regulates cell survival (or cell death in several cases), whereas apoptosis regulates cell death. However, the relationship between autophagy and apoptosis and the regulative mechanism is unclear. We report that steroid hormone 20-hydroxyecdysone (20E) promotes switching from autophagy to apoptosis by increasing intracellular calcium levels in the midgut of the lepidopteran insect Helicoverpa armigera. Autophagy and apoptosis sequentially occurred during midgut programmed cell death under 20E regulation, in which lower concentrations of 20E induced microtubule-associated protein 1 light chain 3–phosphatidylethanolamine (LC3–II, also known as autophagy-related gene 8, ATG8) expression and autophagy. High concentrations of 20E induced cleavage of ATG5 to NtATG5 and pro-caspase-3 to active caspase-3, which led to a switch from autophagy to apoptosis. Blocking autophagy by knockdown of ATG5, ATG7, or ATG12, or with the autophagy inhibitor 3-methyladenine, inhibited 20E-induced autophagy and apoptosis. Blocking apoptosis by using the apoptosis inhibitor Ac-DEVD-CHO did not prevent 20E-induced autophagy, suggesting that apoptosis relies on autophagy. ATG5 knockdown resulted in abnormal pupation and delayed pupation time. High concentrations of 20E induced high levels of intracellular Ca2+, NtATG5, and active caspase-3, which mediated the switch from autophagy to apoptosis. Blocking 20E-mediated increase of cellular Ca2+ caused a decrease of NtATG5 and active caspase-3 and repressed the transformation from autophagy to apoptosis, thereby promoting cell survival. 20E induces an increase in the concentration of intracellular Ca2+, thereby switching autophagic cell survival to apoptotic cell death.
      Graphical abstract image

      PubDate: 2016-11-02T15:10:10Z
      DOI: 10.1016/j.ibmb.2016.10.004
      Issue No: Vol. 79 (2016)
  • Regulation of cuticular hydrocarbon profile maturation by Drosophila
           tanning hormone, bursicon, and its interaction with desaturase activity
    • Authors: Justin Flaven-Pouchon; Jean-Pierre Farine; John Ewer; Jean-François Ferveur
      Pages: 87 - 96
      Abstract: Publication date: Available online 26 October 2016
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Justin Flaven-Pouchon, Jean-Pierre Farine, John Ewer, Jean-François Ferveur
      Shortly after emergence the exoskeleton (cuticle) of adult insects is rapidly expanded, hardened (sclerotized), and pigmented (melanized). In parallel with this process, the oenocytes, which are large polyploid cells located below the abdominal epidermis, secrete onto the cuticle a cocktail of cuticular hydrocarbons (CHs) and waxes. These improve the waterproofing of the cuticle, and also provide important chemosensory and pheromonal cues linked with gender, age, and species differentiation. The hardening and pigmentation of the new cuticle are controlled by the neurohormone, bursicon, and its receptor, encoded by the DLGR2 receptor, rickets (rk); by contrast, little is known about the timecourse of changes in CH profile and about the role of bursicon in this process. Here we show in Drosophila that rk function is also required for the normal maturation of the fly's CH profile, with flies mutant for rk function showing dramatically elevated levels of CHs. Interestingly, this effect is mostly abrogated by mutations in the Δ9 desaturase encoded by the desaturase1 gene, which introduces a first double bond into elongated fatty-acid chains, suggesting that desaturase1 acts downstream of rk. In addition, flies mutant for rk showed changes in the absolute and relative levels of specific 7-monoenes (in males) and 7,11-dienes (in females). The fact that these differences in CH amounts were obtained using extractions of very different durations suggests that the particular CH profile of flies mutant for rk is not simply due to their unsclerotized cuticle but that bursicon may be involved in the process of CH biosynthesis itself.
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      PubDate: 2016-11-02T15:10:10Z
      DOI: 10.1016/j.ibmb.2016.10.007
      Issue No: Vol. 79 (2016)
  • Functional analysis of inhibitor of apoptosis 1 of the silkworm Bombyx
    • Authors: Rina Hamajima; Asako Iwamoto; Moe Tomizaki; Ikue Suganuma; Koji Kitaguchi; Michihiro Kobayashi; Hayato Yamada; Motoko Ikeda
      Pages: 97 - 107
      Abstract: Publication date: Available online 29 October 2016
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Rina Hamajima, Asako Iwamoto, Moe Tomizaki, Ikue Suganuma, Koji Kitaguchi, Michihiro Kobayashi, Hayato Yamada, Motoko Ikeda
      Recent advances in genome-wide surveys have revealed a number of lepidopteran insect homologs of mammalian and Drosophila genes that are responsible for apoptosis regulation. However, the underlying molecular mechanisms for apoptosis regulation in lepidopteran insect cells remain poorly understood. In the present study, we demonstrated that the transfection of Bombyx mori BM-N cells with dsRNA against the B. mori cellular iap1 gene (cbm-iap1) induces severe apoptosis that is accompanied by an increase of caspase-3-like protease activity. In these apoptotic cells, the cleaved form of the endogenous initiator caspase Dronc (Bm-Dronc) was detected, indicating that cBm-IAP1 protein depletion by RNAi silencing resulted in the activation of Bm-Dronc. In transient expression assays in BM-N cells, cBm-IAP1 suppressed the apoptosis triggered by Bm-Dronc overexpression and depressed the elevation of caspase-3-like protease activity, but also increased the cleaved form of Bm-Dronc protein. cBm-IAP1 also suppressed the caspase-3-like protease activity stimulated by Bm-caspase-1 overexpression. Co-immunoprecipitation experiments demonstrated that cBm-IAP1 strongly interacts with Bm-Dronc, but only has weak affinity for Bm-caspase-1. Transient expression analyses showed that truncated cBm-IAP1 proteins defective in the BIR1, BIR2 or RING domain were unable to suppress Bm-Dronc-induced apoptosis. In addition, BM-N cells expressing truncated cBm-IAP1 proteins underwent apoptosis, suggesting that intact cBm-IAP1, which has anti-apoptotic activity, was replaced or displaced by the overexpressed truncated cBm-IAP1 proteins, which are incapable of interfering with the apoptotic caspase cascade. Taken together, the present results demonstrate that cBm-IAP1 is a vital negative regulator of apoptosis in BM-N cells and functions by preventing the activation and/or activity of Bm-Dronc and Bm-caspase-1.
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      PubDate: 2016-11-02T15:10:10Z
      DOI: 10.1016/j.ibmb.2016.10.012
      Issue No: Vol. 79 (2016)
  • Digestive proteolysis in the Colorado potato beetle, Leptinotarsa
           decemlineata: Activity-based profiling and imaging of a multipeptidase
    • Authors: Jaroslav Srp; Martina Nussbaumerová; Martin Horn; Michael Mareš
      Pages: 1 - 11
      Abstract: Publication date: Available online 15 August 2016
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Jaroslav Srp, Martina Nussbaumerová, Martin Horn, Michael Mareš
      The Colorado potato beetle (CPB), Leptinotarsa decemlineata, is a major pest of potato plants, and its digestive system is a promising target for development of pest control strategies. This work focuses on functional proteomic analysis of the digestive proteolytic enzymes expressed in the CPB gut. We identified a set of peptidases using imaging with specific activity-based probes and activity profiling with selective substrates and inhibitors. The secreted luminal peptidases were classified as: (i) endopeptidases of cathepsin D, cathepsin L, and trypsin types and (ii) exopeptidases with aminopeptidase (cathepsin H), carboxypeptidase (serine carboxypeptidase, prolyl carboxypeptidase), and carboxydipeptidase (cathepsin B) activities. The proteolytic arsenal also includes non-luminal peptidases with prolyl oligopeptidase and metalloaminopeptidase activities. Our results indicate that the CPB gut employs a multienzyme network of peptidases with complementary specificities to efficiently degrade ingested proteins. This proteolytic system functions in both CPB larvae and adults and is controlled mainly by cysteine and aspartic peptidases and supported by serine and metallopeptidases. The component enzymes identified here are potential targets for inhibitors with tailored specificities that could be engineered into potato plants to confer resistance to CPB.
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      PubDate: 2016-08-18T02:27:48Z
      DOI: 10.1016/j.ibmb.2016.08.004
      Issue No: Vol. 78 (2016)
  • Farnesyl biliverdins IXα are novel ligands of biliproteins from moths of
           the Noctuoidea superfamily: A chemosystematic view of the Lepidoptera
    • Authors: Hartmut Kayser; Manfred Nimtz
      Pages: 12 - 19
      Abstract: Publication date: Available online 28 August 2016
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Hartmut Kayser, Manfred Nimtz
      Bilins, derived from biliverdin IXα, are known from animals, plants and microorganisms, where they play vital roles as light-absorbing pigments. Bilins occur also in many insects. Recently, we discovered in insects a novel structural type of bilins with a farnesyl substituent at pyrrole ring A of biliverdin IXα. The first of these unusual bilins with a molecular mass of 852 (C48H60O10N4) was identified in Cerura vinula, subsequently in Spodoptera littoralis; both species are members of the Noctuoidea superfamily of moths. From an evolutionary point of view, it was of interest to examine other species and families of this monophyletic clade. Here, we show that other moths species in this clade (three Notodontidae species, one Erebidae species, and one Noctuidae species) have farnesylated biliverdins IXα that are present as a mixture of three bilins, differing by the number of oxygen atoms (O8-10). These bilins are associated with typical hemolymph storage proteins, which were identified by mass spectroscopic sequencing of tryptic peptides as arylphorins (a class of 500-kDa hexamerins) in the Notodontidae and Erebidae families, and as 350-kDa very high-density lipoproteins in the Noctuidae family. Circular dichroism spectroscopy revealed that the bilins adopt opposite conformations in complex with the two different classes of proteins. At present, farnesylated biliverdins and IXα-isomers of bilins in general are known only from species of the Noctuoidea clade; the sister clades of Bombycoidea and Papilionoidea synthesise the IXγ-isomer of biliverdin and derivatives thereof.
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      PubDate: 2016-08-31T03:51:09Z
      DOI: 10.1016/j.ibmb.2016.08.007
      Issue No: Vol. 78 (2016)
  • Multiple cis-acting elements involved in up-regulation of a cytochrome
           P450 gene conferring resistance to deltamethrin in small brown
           planthopper, Laodelphax striatellus (Fallén)
    • Authors: Jian Pu; Haina Sun; Jinda Wang; Min Wu; Kangxu Wang; Ian Denholm; Zhaojun Han
      Pages: 20 - 28
      Abstract: Publication date: Available online 31 August 2016
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Jian Pu, Haina Sun, Jinda Wang, Min Wu, Kangxu Wang, Ian Denholm, Zhaojun Han
      As well as arising from single point mutations in binding sites or detoxifying enzymes, it is likely that insecticide resistance mechanisms are frequently controlled by multiple genetic factors, resulting in resistance being inherited as a quantitative trait. However, empirical evidence for this is still rare. Here we analyse the causes of up-regulation of CYP6FU1, a monoxygenase implicated in resistance to deltamethrin in the rice pest Laodelphax striatellus. The 5′-flanking region of this gene was cloned and sequenced from individuals of a susceptible and a resistant strain. A luminescent reporter assay was used to evaluate different 5′-flanking regions and their fragments for promoter activity. Mutations enhancing promoter activity in various fragments were characterized, singly and in combination, by site mutation recovery. Nucleotide diversity in flanking sequences was greatly reduced in deltamethrin-resistant insects compared to susceptible ones. Phylogenetic sequence analysis found that CYP6FU1 had five different types of 5′-flanking region. All five types were present in a susceptible strain but only a single type showing the highest promoter activity was present in a resistant strain. Four cis-acting elements were identified whose influence on up-regulation was much more pronounced in combination than when present singly. Of these, two were new transcription factor (TF) binding sites produced by mutations, another one was also a new TF binding site alternated from an existing one, and the fourth was a unique transcription start site. These results demonstrate that multiple cis-acting elements are involved in up-regulating CYP6FU1 to generate a resistance phenotype.
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      PubDate: 2016-09-06T00:52:58Z
      DOI: 10.1016/j.ibmb.2016.08.008
      Issue No: Vol. 78 (2016)
  • Precise genome editing in the silkworm Bombyx mori using TALENs and ds-
           and ssDNA donors – A practical approach
    • Authors: Yoko Takasu; Isao Kobayashi; Toshiki Tamura; Keiro Uchino; Hideki Sezutsu; Michal Zurovec
      Pages: 29 - 38
      Abstract: Publication date: Available online 25 August 2016
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Yoko Takasu, Isao Kobayashi, Toshiki Tamura, Keiro Uchino, Hideki Sezutsu, Michal Zurovec
      Engineered nucleases are able to introduce double stranded breaks at desired genomic locations. The breaks can be repaired by an error-prone non-homologous end joining (NHEJ) mechanism, or the repair process can be exploited to introduce precise DNA modifications by homology-directed repair (HDR) when provided with a suitable donor template. We designed a series of DNA donors including long dsDNA plasmids as well as short ssDNA oligonucleotides and compared the effectiveness of their utilization during gene targeting with highly efficient transcription activator-like effector nucleases (TALENs). While the use of long dsDNA donors for the incorporation of larger DNA fragments in Bombyx is still a problem, short single-stranded oligodeoxynucleotides (ssODNs) are incorporated quite efficiently. We show that appropriately designed ssODNs were integrated into germ cells in up to 79% of microinjected individuals and describe in more detail the conditions for the precise genome editing of Bombyx genes. We specify the donor sequence requirements that affected knock-in efficiency, and demonstrate the successful applications of this method of sequence deletion, insertion and replacement in the Bombyx genome.
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      PubDate: 2016-08-27T03:06:29Z
      DOI: 10.1016/j.ibmb.2016.08.006
      Issue No: Vol. 78 (2016)
  • Metabolism of poplar salicinoids by the generalist herbivore Lymantria
           dispar (Lepidoptera)
    • Authors: G. Andreas Boeckler; Christian Paetz; Peter Feibicke; Jonathan Gershenzon; Sybille B. Unsicker
      Pages: 39 - 49
      Abstract: Publication date: Available online 5 August 2016
      Source:Insect Biochemistry and Molecular Biology
      Author(s): G. Andreas Boeckler, Christian Paetz, Peter Feibicke, Jonathan Gershenzon, Sybille B. Unsicker
      The survival of insect herbivores on chemically defended plants may often depend on their ability to metabolize these defense compounds. However, only little knowledge is available on how insects actually process most plant defense compounds. We investigated the metabolism of salicinoids, a major group of phenolic glycosides in poplar and willow species, by a generalist herbivore, the gypsy moth (Lymantria dispar). Seven salicinoid metabolites identified in gypsy moth caterpillar feces were mostly conjugates with glucose, cysteine or glycine. Two of the glucosides were phosphorylated, a feature not previously reported for insect metabolites of plant defense compounds. The origins of these metabolites were traced to specific moieties of three major poplar salicinoids ingested, salicin, salicortin and tremulacin. Based on the observed metabolite patterns we were able to deduce the initial steps of salicinoid breakdown in L. dispar guts, which involves cleavage of ester bonds. The conjugated molecules were effectively eliminated within 24 h after ingestion. Some of the initial breakdown products (salicin and catechol) demonstrated negative effects on insect growth and survival in bioassays on artificial diets. Gypsy moth caterpillars with prior feeding experience on salicinoid-containing poplar foliage converted salicinoids to the identified metabolites more efficiently than caterpillars pre-fed an artificial diet. The majority of the metabolites we identified were also produced by other common poplar-feeding insects. The conversion of plant defenses like salicinoids to a variety of water-soluble sugar, phosphate and amino acid conjugates and their subsequent excretion fits the general detoxification strategy found in insect herbivores and other animals.
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      PubDate: 2016-08-09T01:40:03Z
      DOI: 10.1016/j.ibmb.2016.08.001
      Issue No: Vol. 78 (2016)
  • Pyriproxyfen is metabolized by P450s associated with pyrethroid resistance
           in An. gambiae
    • Authors: Cristina Yunta; Nelson Grisales; Szilárd Nász; Kay Hemmings; Patricia Pignatelli; Michael Voice; Hilary Ranson; Mark J.I. Paine
      Pages: 50 - 57
      Abstract: Publication date: Available online 7 September 2016
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Cristina Yunta, Nelson Grisales, Szilárd Nász, Kay Hemmings, Patricia Pignatelli, Michael Voice, Hilary Ranson, Mark J.I. Paine
      Pyrethroid resistance is widespread in the malaria vector Anopheles gambiae leading to concerns about the future efficacy of bednets with pyrethroids as the sole active ingredient. The incorporation of pyriproxyfen (PPF), a juvenile hormone analogue, into pyrethroid treated bednets is being trialed in Africa. Pyrethroid resistance is commonly associated with elevated levels of P450 expression including CYPs 6M2, 6P2, 6P3, 6P4, 6P5, 6Z2 and 9J5. Having expressed these P450s in E. coli we find all are capable of metabolizing PPF. Inhibition of these P450s by permethrin, deltamethrin and PPF was also examined. Deltamethrin and permethrin were moderate inhibitors (IC50 1–10 μM) of diethoxyfluorescein (DEF) activity for all P450s apart from CYP6Z2 (IC50 > 10 μM), while PPF displayed weaker inhibition of all P450s (IC50 > 10 μM) except CYP's 6Z2 and 6P2 (IC50 1–10 μM). We found evidence of low levels of cross resistance between PPF and other insecticide classes by comparing the efficacy of PPF in inhibiting metamorphosis and inducing female sterility in an insecticide susceptible strain of An. gambiae and a multiple resistant strain from Cote d’Ivoire.
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      PubDate: 2016-09-11T01:03:59Z
      DOI: 10.1016/j.ibmb.2016.09.001
      Issue No: Vol. 78 (2016)
  • Variation in RNAi efficacy among insect species is attributable to dsRNA
           degradation in vivo
    • Authors: Kangxu Wang; Yingchuan Peng; Jian Pu; Wenxi Fu; Jiale Wang; Zhaojun Han
      Pages: 1 - 9
      Abstract: Publication date: October 2016
      Source:Insect Biochemistry and Molecular Biology, Volume 77
      Author(s): Kangxu Wang, Yingchuan Peng, Jian Pu, Wenxi Fu, Jiale Wang, Zhaojun Han
      RNA interference (RNAi) has become an essential technique in entomology research. However, RNAi efficiency appears to vary significantly among insect species. Here, the sensitivity of four insect species from different orders to RNAi was compared to understand the reason for this variation. A previously reported method was modified to monitor trace amounts of double-stranded RNA (dsRNA). After the administration of dsRNA, the dynamics of its content was determined in the hemolymph, in addition to the capability of its degradation in both the hemolymph and the midgut juice. The results showed that injection of dsRNA targeting the homologous chitinase gene in Periplaneta americana, Zophobas atratus, Locusta migratoria, and Spodoptera litura, with doses (1.0, 2.3, 11.5, and 33.0 μg, respectively) resulting in the same initial hemolymph concentration, caused 82%, 78%, 76%, and 20% depletion, respectively, whereas feeding doses based on body weight (24, 24, 36, and 30 μg) accounted for 47%, 28%, 5%, and 1% depletion. The sensitivity of insects to RNAi was observed to be as follows: P. americana > Z. atratus >> L. migratoria >> S. litura. In vivo monitoring revealed that RNAi effects among these insect species were highly correlated with the hemolymph dsRNA contents. Furthermore, in vitro experiments demonstrated that the hemolymph contents after dsRNA injection were dependent on hemolymph degradation capacities, and on the degradation capabilities in the midgut juice, when dsRNA was fed. In conclusion, the RNAi efficacy in different insect species was observed to depend on the enzymatic degradation of dsRNA, which functions as the key factor determining the inner target exposure dosages. Thus, enzymatic degradation in vivo should be taken into consideration for efficient use of RNAi in insects.
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      PubDate: 2016-08-04T01:24:27Z
      DOI: 10.1016/j.ibmb.2016.07.007
      Issue No: Vol. 77 (2016)
  • Functional evaluation of Heat Shock Proteins 70 (HSP70/HSC70) on Rhodnius
           prolixus (Hemiptera, Reduviidae) physiological responses associated with
           feeding and starvation
    • Authors: Rafaela M.M. Paim; Ricardo N. Araujo; Miguel Leis; Mauricio R.V. Sant'anna; Nelder F. Gontijo; Claudio R. Lazzari; Marcos H. Pereira
      Pages: 10 - 20
      Abstract: Publication date: Available online 1 August 2016
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Rafaela M.M. Paim, Ricardo N. Araujo, Miguel Leis, Mauricio R.V. Sant'anna, Nelder F. Gontijo, Claudio Lazzari, Marcos H. Pereira
      Blood-sucking vectors must overcome thermal stress caused by intake of proportionally large amounts of warm blood from their hosts. In response to this, Heat Shock Proteins (HSPs) such as the widely studied HSP70 family (the inducible HSP70 and the cognate form HSC70, known for their role in preserving essential cellular functions) are rapidly up-regulated in their tissues. The triatomine Rhodnius prolixus is an important vector of Trypanosoma cruzi, the causative pathogen of Chagas’ disease, and is also a model organism for studying insect biology and physiology. In this work, we observed that the expression of Rhodnius prolixus HSP70 was rapidly up-regulated in response to thermal shocks (0 °C and 40 °C) and also during the first hours after feeding on blood. HSP70/HSC70 RNAi knockdown elicited important alterations in R. prolixus physiological responses triggered by blood meal and starvation. HSP70/HSC70 knockdown insects showed lower resistance to prolonged starvation in comparison to appropriate controls, dying between 32 and 40 days after dsRNA injection. After blood feeding, the physiological effects of HSP70/HSC70 knockdown were more prominent and the insects died even earlier, within 14–20 days after feeding (21–27 days after dsRNA injection). These bugs showed impaired blood processing and digestion, reduced energetic metabolism and the midgut immune responses were compromised. Our findings suggest that HSP70/HSC70 depletion affected R. prolixus in starvation or fed conditions. After feeding, the arrival of blood in the digestive tract of knockdown insects fails to activate essential signaling pathways involved in blood processing, producing several alterations in their physiological processes enough to generate a premature death.
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      PubDate: 2016-08-04T01:24:27Z
      DOI: 10.1016/j.ibmb.2016.07.011
      Issue No: Vol. 77 (2016)
  • Artificial miRNA-mediated silencing of ecdysone receptor (EcR) affects
           larval development and oogenesis in Helicoverpa armigera
    • Authors: Sneha Yogindran; Manchikatla Venkat Rajam
      Pages: 21 - 30
      Abstract: Publication date: Available online 29 July 2016
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Sneha Yogindran, Manchikatla Venkat Rajam
      The insect pests are real threat to farmers as they affect the crop yield to a great extent. The use of chemical pesticides for insect pest control has always been a matter of concern as they pollute the environment and are also harmful for human health. Bt (Bacillus thuringensis) technology helped the farmers to get rid of the insect pests, but experienced a major drawback due to the evolution of insects gaining resistance towards these toxins. Hence, alternative strategies are high on demand to control insect pests. RNA-based gene silencing is emerging as a potential tool to tackle with this problem. In this study, we have shown the use of artificial microRNA (amiRNA) to specifically target the ecdysone receptor (EcR) gene of Helicoverpa armigera (cotton bollworm), which attacks several important crops like cotton, tomato chickpea, pigeon pea, etc and causes huge yield losses. Insect let-7a precursor miRNA (pre-miRNA) backbone was used to replace the native miRNA with that of amiRNA. The precursor backbone carrying the 21 nucleotide amiRNA sequence targeting HaEcR was cloned in bacterial L4440 vector for in vitro insect feeding experiments. Larvae fed with Escherichia coli expressing amiRNA-HaEcR showed a reduction in the expression of target gene as well as genes involved in the ecdysone signaling pathway downstream to EcR and exhibited mortality and developmental defects. Stem-loop RT-PCR revealed the presence of amiRNA in the insect larvae after feeding bacteria expressing amiRNA-HaEcR, which was otherwise absent in controls. We also found a significant drop in the reproduction potential (oogenesis) of moths which emerged from treated larvae as compared to control. These results demonstrate the successful use of an insect pre-miRNA backbone to express amiRNA for gene silencing studies in insects. The method is cost effective and can be exploited as an efficient and alternative tool for insect pest management.
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      PubDate: 2016-08-04T01:24:27Z
      DOI: 10.1016/j.ibmb.2016.07.009
      Issue No: Vol. 77 (2016)
  • Overexpression of jumu induces melanotic nodules by activating Toll
           signaling in Drosophila
    • Authors: Gaoqun Zhang; Yangguang Hao; Li Hua Jin
      Pages: 31 - 38
      Abstract: Publication date: Available online 6 August 2016
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Gaoqun Zhang, Yangguang Hao, Li Hua Jin
      Melanotic nodules are commonly assumed to be caused by an abnormal immune response. Several hematopoietic mutants and signaling pathways, including the Toll, JAK/STAT, Ras and JNK pathways, can cause melanotic nodules to develop when specifically activated in hemocytes. Here, we used the UAS-Gal4 system to overexpress jumeaux (jumu) in the fly immune response system. Jumeaux (Jumu) is a new member of the winged-helix/forkhead (WH/FKH) gene family of transcription factors, which plays an important role in the growth and morphogenesis of Drosophila and participates in the proliferation and differentiation of hemocytes. Overexpressing jumu in both hemocytes and the fat body generated many melanotic nodules in larvae and adult flies. The nodules observed in the fat body were surrounded by large numbers of blood cells through a process that appeared similar to foreign body encapsulation. This phenomenon is caused by Toll pathway activation and leads to blood cells deposited in the fat body. In addition, we also report the dissociation of fat cells and the abnormal proliferation and differentiation of blood cells. These results suggest a Jumu-mediated crosstalk between hematopoiesis and the fat body, especially during the Toll-dependent formation of melanotic nodules.
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      PubDate: 2016-08-09T01:40:03Z
      DOI: 10.1016/j.ibmb.2016.08.002
      Issue No: Vol. 77 (2016)
  • Molecular and functional characterization of Bemisia tabaci aquaporins
           reveals the water channel diversity of hemipteran insects
    • Authors: Evelien Van Ekert; François Chauvigné; Roderick Nigel Finn; Lolita G. Mathew; J. Joe Hull; Joan Cerdà; Jeffrey A. Fabrick
      Pages: 39 - 51
      Abstract: Publication date: Available online 2 August 2016
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Evelien van Ekert, François Chauvigné, Roderick Nigel Finn, Lolita G. Mathew, J. Joe Hull, Joan Cerdà, Jeffrey A. Fabrick
      The Middle East-Asia Minor 1 (MEAM1) whitefly, Bemisia tabaci (Gennadius) is an economically important pest of food, fiber, and ornamental crops. This pest has evolved a number of adaptations to overcome physiological challenges, including 1) the ability to regulate osmotic stress between gut lumen and hemolymph after imbibing large quantities of a low nitrogen, sugar-rich liquid diet; 2) the ability to avoid or prevent dehydration and desiccation, particularly during egg hatching and molting; and 3) to be adapted for survival at elevated temperatures. One superfamily of proteins involved in the maintenance of fluid homeostasis in many organisms includes the aquaporins, which are integral membrane channel proteins that aid in the rapid flux of water and other small solutes across biological membranes. Here, we show that B. tabaci has eight aquaporins (BtAqps), of which seven belong to the classical aquaporin 4-related grade of channels, including Bib, Drip, Prip, and Eglps and one that belongs to the unorthodox grade of aquaporin 12-like channels. B. tabaci has further expanded its repertoire of water channels through the expression of three BtDrip2 amino-terminal splice variants, while other hemipteran species express amino- or carboxyl-terminal isoforms of Drip, Prip, and Eglps. Each BtAqp has unique transcript expression profiles, cellular localization, and/or substrate preference. Our phylogenetic and functional data reveal that hemipteran insects lost the classical glp genes, but have compensated for this by duplicating the eglp genes early in their evolution to comprise at least three separate clades of glycerol transporters.
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      PubDate: 2016-08-04T01:24:27Z
      DOI: 10.1016/j.ibmb.2016.07.010
      Issue No: Vol. 77 (2016)
  • Physiological roles of trehalose in Leptinotarsa larvae revealed by RNA
           interference of trehalose-6-phosphate synthase and trehalase genes
    • Authors: Ji-Feng Shi; Qing-Yu Xu; Qiang-Kun Sun; Qing-Wei Meng; Li-Li Mu; Wen-Chao Guo; Guo-Qing Li
      Pages: 52 - 68
      Abstract: Publication date: Available online 11 August 2016
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Ji-Feng Shi, Qing-Yu Xu, Qiang-Kun Sun, Qing-Wei Meng, Li-Li Mu, Wen-Chao Guo, Guo-Qing Li
      Trehalose is proposed to serve multiple physiological roles in insects. However, its importance remains largely unconfirmed. In the present paper, we knocked down either a trehalose biosynthesis gene (trehalose-6-phosphate synthase, LdTPS) or each of three degradation genes (soluble trehalases LdTRE1a, LdTRE1b or membrane-bound LdTRE2) in Leptinotarsa decemlineata by RNA interference (RNAi). Knockdown of LdTPS decreased trehalose content and caused larval and pupal lethality. The LdTPS RNAi survivors consumed a greater amount of foliage, obtained a heavier body mass, accumulated more glycogen, lipid and proline, and had a smaller amount of chitin compared with the controls. Ingestion of trehalose but not glucose rescued the food consumption increase and larval mass rise, increased survivorship, and recovered glycogen, lipid and chitin to the normal levels. In contrast, silencing of LdTRE1a increased trehalose content and resulted in larval and pupal lethality. The surviving LdTRE1a RNAi hypomorphs fed a smaller quantity of food, had a lighter body weight, depleted lipid and several glucogenic amino acids, and contained a smaller amount of chitin. Neither trehalose nor glucose ingestion rescued these LdTRE1a RNAi defects. Silencing of LdTRE1b caused little effects. Knockdown of LdTRE2 caused larval death, increased trehalose contents in several tissues and diminished glycogen in the brain-corpora cardiaca-corpora allata complex (BCC). Feeding glucose but not trehalose partially rescued the high mortality rate and recovered glycogen content in the BCC. It seems that trehalose is involved in feeding regulation, sugar absorption, brain energy supply and chitin biosynthesis in L. decemlineata larvae.
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      PubDate: 2016-08-13T02:01:30Z
      DOI: 10.1016/j.ibmb.2016.07.012
      Issue No: Vol. 77 (2016)
  • Determination of juvenile hormone titers by means of LC-MS/MS/MS and a
           juvenile hormone-responsive Gal4/UAS system in Aedes aegypti mosquitoes
    • Authors: Bo Zhao; Yuan Hou; Jianjun Wang; Vladimir A. Kokoza; Tusar T. Saha; Xue-Li Wang; Ling Lin; Zhen Zou; Alexander S. Raikhel
      Pages: 69 - 77
      Abstract: Publication date: Available online 12 August 2016
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Bo Zhao, Yuan Hou, Jianjun Wang, Vladimir A. Kokoza, Tusar T. Saha, Xue-Li Wang, Ling Lin, Zhen Zou, Alexander S. Raikhel
      In anautogenous mosquitoes, juvenile hormone III (JH) plays an essential role in female post-eclosion (PE) development, preparing them for subsequent blood feeding and egg growth. We re-examined the JH titer during the reproductive cycle of female Aedes aegypti mosquitoes. Using liquid chromatography coupled with triple tandem mass spectrometry (LC-MS/MS/MS), we have shown that it reaches its peak at 48–54 h PE in the female hemolymph and at 72 h PE in whole body extracts. This method represents an effective assay for determination of JH titers. The 2.1-kb 5’ promoter region of the Early Trypsin (ET) gene, which is specifically expressed in the female midgut under the control of JH during the PE phase, was utilized to genetically engineer the Ae. aegypti mosquito line with the ET-Gal4 activator. We then established the ET-GAL4>UAS-enhanced green fluorescent protein (EGFP) system in Ae. aegypti. In ET-Gal4>UAS-EGFP female mosquitoes, the intensity of the midgut-specific EGFP signal was observed to correspond to the ET gene transcript level and follow the JH titer during the PE phase. The EGFP signal and the EGFP transcript level were significantly diminished in midguts of transgenic female mosquitoes after RNA interference depletion of the JH receptor Methoprene-tolerant (Met), providing evidence of the control of ET gene expression by Met. Topical JH application caused premature enhancement of the EGFP signal and the EGFP transcript level in midguts of newly eclosed ET-Gal4>UAS-EGFP female mosquitoes, in which endogenous JH titer is still low. Hence, this novel ET-Gal4>UAS system permits JH-dependent gene overexpression in the midgut of Ae. aegypti female mosquitoes prior to a blood meal.
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      PubDate: 2016-08-13T02:01:30Z
      DOI: 10.1016/j.ibmb.2016.08.003
      Issue No: Vol. 77 (2016)
  • Electrophysiological characterization of ivermectin triple actions on
    • Authors: Toshinori Fuse; Tomo Kita; Yunosuke Nakata; Fumiyo Ozoe; Yoshihisa Ozoe
      Pages: 78 - 86
      Abstract: Publication date: Available online 16 August 2016
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Toshinori Fuse, Tomo Kita, Yunosuke Nakata, Fumiyo Ozoe, Yoshihisa Ozoe
      Ivermectin (IVM) is a macrocyclic lactone that exerts antifilarial, antiparasitic, and insecticidal effects on nematodes and insects by acting on L-glutamic acid-gated chloride channels (GluCls). IVM also acts as an allosteric modulator of various other ion channels. Although the IVM binding site in the Caenorhabditis elegans GluCl was identified by X-ray crystallographic analysis, the mechanism of action of IVM in insects is not well defined. We therefore examined the action of IVM on the housefly (Musca domestica) GluCl and γ-aminobutyric acid (GABA)-gated ion channel (GABACl). For both channels, IVM induced currents by itself, potentiated currents induced by low concentrations of agonists, and inhibited currents induced by high concentrations of agonists. Despite exerting common actions on both types of channels, GluCls were more susceptible to IVM actions than GABACls, indicating that GluCls are the primary target of IVM. Substitution of an amino acid residue in the third transmembrane segment (G312M in GluCls, and G333A and G333M in GABACls) resulted in significantly reduced levels or loss of activation, potentiation, and antagonism of the channels, indicating that these three actions result from the interaction of IVM with amino acid residues in the transmembrane intersubunit crevice.
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      PubDate: 2016-08-18T02:27:48Z
      DOI: 10.1016/j.ibmb.2016.08.005
      Issue No: Vol. 77 (2016)
  • In search of a function of Manduca sexta hemolymph protease-1 in the
           innate immune system
    • Authors: Fan Yang; Yang Wang; Yan He; Haobo Jiang
      Pages: 1 - 10
      Abstract: Publication date: September 2016
      Source:Insect Biochemistry and Molecular Biology, Volume 76
      Author(s): Fan Yang, Yang Wang, Yan He, Haobo Jiang
      Extracellular serine protease cascades mediate immune signaling and responses in insects. In the tobacco hornworm Manduca sexta, nearly 30 serine proteases (SPs) and their homologs (SPHs) are cloned from hemocytes and fat body. Some of them participate in prophenoloxidase (proPO) activation and proSpätzle processing. Here we report the cDNA cloning of hemolymph protease-1b (HP1b), which is 90% identical and 95% similar to HP1a (formerly HP1). The HP1a and HP1b mRNA levels in hemocytes was down- and up-regulated after an immune challenge, respectively. Quantitative real-time polymerase chain reactions revealed their tissue-specific and development-dependent expression, mostly in hemocytes of the feeding larvae. We isolated HP1 precursor (proHP1) from larval hemolymph and observed micro-heterogeneity caused by N-linked glycosylation. Supplementation of the purified proHP1 to plasma samples from naïve larvae or induced ones injected with bacteria caused a small PO activity increase, much lower than those elicited by recombinant proHP1a/b, but no proteolytic cleavage was detected in the zymogens. Incubation of proHP1a/b or their catalytic domains with a cationic detergent, cetylpyridinium chloride, induced an amidase activity that hydrolyzed LDLH-p-nitroanilide. Since LDLH corresponds to the P4–P1 region before the proteolytic activation site of proHP6, we propose that the active but uncleaved proHP1 may cut proHP6 to generate HP6 that in turn activates proPAP1 and proHP8. The catalytic domain of HP1a/b, which by itself does not activate purified proHP6 or hydrolyze LDLH-p-nitroanilide, somehow generated active HP6, HP8, PAP1 and PO in plasma. Together, these results indicate that proHP1 participates in the proPO activation system, although detailed mechanism needs further exploration.
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      PubDate: 2016-08-04T01:24:27Z
      DOI: 10.1016/j.ibmb.2016.06.009
      Issue No: Vol. 76 (2016)
  • Functional validation of cadherin as a receptor of Bt toxin Cry1Ac in
           Helicoverpa armigera utilizing the CRISPR/Cas9 system
    • Authors: Jing Wang; Haonan Zhang; Huidong Wang; Shan Zhao; Yayun Zuo; Yihua Yang; Yidong Wu
      Pages: 11 - 17
      Abstract: Publication date: September 2016
      Source:Insect Biochemistry and Molecular Biology, Volume 76
      Author(s): Jing Wang, Haonan Zhang, Huidong Wang, Shan Zhao, Yayun Zuo, Yihua Yang, Yidong Wu
      Cadherins have been identified as receptors of Bacillus thuringiensis (Bt) Cry1A toxins in several lepidopteran insects including the cotton bollworm, Helicoverpa armigera. Disruption of the cadherin gene HaCad has been genetically linked to resistance to Bt toxin Cry1Ac in H. armigera. By using the CRISPR/Cas9 genome editing system (Clustered Regularly Interspaced Short Palindromic Repeats/CRISPR-associated protein 9), HaCad from the Cry1Ac-susceptible SCD strain of H. armigera was successfully knocked out. A single positive CRISPR event with a frame shift deletion of 4 nucleotides was identified and made homozygous to create a knockout line named SCD-Cad. Western blotting confirmed that HaCad was no longer expressed in the SCD-Cad line while an intact HaCad of 210 kDa was present in the parental SCD strain. Insecticide bioassays were used to show that SCD-Cad exhibited 549-fold resistance to Cry1Ac compared with SCD, but no significant change in susceptibility to Cry2Ab. Our results not only provide strong reverse genetics evidence for HaCad as a functional receptor of Cry1Ac, but also demonstrate that the CRISPR/Cas9 technique can act as a powerful and efficient genome editing tool to study gene function in a global agricultural pest, H. armigera.
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      PubDate: 2016-08-04T01:24:27Z
      DOI: 10.1016/j.ibmb.2016.06.008
      Issue No: Vol. 76 (2016)
  • Characteristics and expression patterns of histone-modifying enzyme
           systems in the migratory locust
    • Authors: Siyuan Guo; Feng Jiang; Pengcheng Yang; Qing Liu; Xianhui Wang; Le Kang
      Pages: 18 - 28
      Abstract: Publication date: September 2016
      Source:Insect Biochemistry and Molecular Biology, Volume 76
      Author(s): Siyuan Guo, Feng Jiang, Pengcheng Yang, Qing Liu, Xianhui Wang, Le Kang
      The density-dependent phase polyphenism in locusts offers an excellent model to investigate the epigenetic regulatory mechanisms underlying phenotypic plasticity. In this study, we identified histone-modifying enzymes mediating histone post-translational modifications, which serve as a major regulatory mechanism of epigenetic processes, on the basis of the whole genome sequence of the migratory locust, Locusta migratoria. We confirmed the existence of various functional histone modifications in the locusts. Compared with other sequenced insect genomes, the locust genome contains a richer repertoire of histone-modifying enzymes. Several locust histone-modifying enzymes display vertebrate-like characteristics, such as the presence of a Sirt3-like gene and multiple alternative splicing of GCN5 gene. Most histone-modifying enzymes are highly expressed in the eggs or in the testis tissues of male adults. Several histone deacetylases and H3K4-specific methyltransferases exhibit differential expression patterns in brain tissues between solitarious and gregarious locusts. These results reveal the main characteristics of histone-modifying enzymes and provide important cues for understanding the epigenetic mechanisms underlying phase polyphenism in locusts.
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      PubDate: 2016-08-04T01:24:27Z
      DOI: 10.1016/j.ibmb.2016.06.010
      Issue No: Vol. 76 (2016)
  • Changes in histone acetylation as potential mediators of pupal diapause in
           the flesh fly, Sarcophaga bullata
    • Authors: J.A. Reynolds; Robin Bautista-Jimenez; D.L. Denlinger
      Pages: 29 - 37
      Abstract: Publication date: September 2016
      Source:Insect Biochemistry and Molecular Biology, Volume 76
      Author(s): J.A. Reynolds, Robin Bautista-Jimenez, D.L. Denlinger
      The growing appreciation that epigenetic processes are integral to the responses of many organisms to changes in the environment suggests a possible role for epigenetics in coordination of insect diapause. The results we present suggest that histone modification may be one type of epigenetic process that contributes to regulation of pupal diapause in the flesh fly, Sarcophaga bullata. Reduction in total histone H3 acetylation in diapausing pupae, shifts in mRNA expression profiles of genes encoding histone acetyltransferase (HAT) and histone deacetylase (HDAC) in pre-diapause, diapause and post-diapause flies compared to their nondiapause counterparts, and alterations in HDAC enzyme activity during and post-diapause lend support to the hypothesis that this specific type of histone modification is involved in regulating diapause programming, maintenance, and termination. Transcription of genes encoding HDAC1, HDAC3, HDAC6, and Sirtuin2 were all upregulated in photosensitive first instar larvae programmed to enter pupal diapause, suggesting that histone deacetylation may be linked to the early decision to enter diapause. A 50% reduction in transcription of hdac3 and a corresponding 30% reduction in HDAC activity during diapause suggest that removal of acetyl groups from histones primarily occurs prior to diapause entry and that further histone deacetylation is not necessary to maintain diapause. Transcription of the HDAC genes was quickly elevated when diapause was terminated, followed by an increase in enzyme activity after a short delay. A maternal effect operating in these flies prevents pupal diapause in progeny whose mothers experienced pupal diapause, even if the progeny are reared in strong diapause-inducing short-day conditions. Such nondiapausing pupae had HDAC transcription profiles nearly identical to the profiles seen in nondiapausing pupae generated under a long-day photoperiod. Together, these results provide consistent evidence for histone acetylation and deacetylation as regulators of this insect's developmental trajectory.
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      PubDate: 2016-08-04T01:24:27Z
      DOI: 10.1016/j.ibmb.2016.06.012
      Issue No: Vol. 76 (2016)
  • Dipeptidyl peptidase 4 – An important digestive peptidase in
           Tenebrio molitor larvae
    • Authors: Valeriia F. Tereshchenkova; Irina A. Goptar; Irina A. Kulemzina; Dmitry P. Zhuzhikov; Marina V. Serebryakova; Mikhail A. Belozersky; Yakov E. Dunaevsky; Brenda Oppert; Irina Yu Filippova; Elena N. Elpidina
      Pages: 38 - 48
      Abstract: Publication date: September 2016
      Source:Insect Biochemistry and Molecular Biology, Volume 76
      Author(s): Valeriia F. Tereshchenkova, Irina A. Goptar, Irina A. Kulemzina, Dmitry P. Zhuzhikov, Marina V. Serebryakova, Mikhail A. Belozersky, Yakov E. Dunaevsky, Brenda Oppert, Irina Yu Filippova, Elena N. Elpidina
      Dipeptidyl peptidase 4 (DPP 4) is a proline specific serine peptidase that plays an important role in different regulatory processes in mammals. In this report, we isolated and characterized a unique secreted digestive DPP 4 from the anterior midgut of a stored product pest, Tenebrio molitor larvae (TmDPP 4), with a biological function different than that of the well-studied mammalian DPP 4. The sequence of the purified enzyme was confirmed by mass-spectrometry, and was identical to the translated RNA sequence found in a gut EST database. The purified peptidase was characterized according to its localization in the midgut, and substrate specificity and inhibitor sensitivity were compared with those of human recombinant DPP 4 (rhDPP 4). The T. molitor enzyme was localized mainly in the anterior midgut of the larvae, and 81% of the activity was found in the fraction of soluble gut contents, while human DPP 4 is a membrane enzyme. TmDPP 4 was stable in the pH range 5.0–9.0, with an optimum activity at pH 7.9, similar to human DPP 4. Only specific inhibitors of serine peptidases, diisopropyl fluorophosphate and phenylmethylsulfonyl fluoride, suppressed TmDPP 4 activity, and the specific dipeptidyl peptidase inhibitor vildagliptin was most potent. The highest rate of TmDPP 4 hydrolysis was found for the synthetic substrate Arg-Pro-pNA, while Ala-Pro-pNA was a better substrate for rhDPP 4. Related to its function in the insect midgut, TmDPP 4 efficiently hydrolyzed the wheat storage proteins gliadins, which are major dietary proteins of T. molitor.
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      PubDate: 2016-08-04T01:24:27Z
      DOI: 10.1016/j.ibmb.2016.07.003
      Issue No: Vol. 76 (2016)
  • Identification of major Toxoneuron nigriceps venom proteins using an
           integrated transcriptomic/proteomic approach
    • Authors: Simona Laurino; Gerarda Grossi; Pietro Pucci; Angela Flagiello; Sabino Aurelio Bufo; Giuliana Bianco; Rosanna Salvia; S. Bradleigh Vinson; Heiko Vogel; Patrizia Falabella
      Pages: 49 - 61
      Abstract: Publication date: September 2016
      Source:Insect Biochemistry and Molecular Biology, Volume 76
      Author(s): Simona Laurino, Gerarda Grossi, Pietro Pucci, Angela Flagiello, Sabino Aurelio Bufo, Giuliana Bianco, Rosanna Salvia, S. Bradleigh Vinson, Heiko Vogel, Patrizia Falabella
      Endoparasitoids in the order Hymenoptera are natural enemies of several herbivorous insect pest species. During oviposition they inject a mixture of factors, which include venom, into the host, ensuring the successful parasitism and the development of their progeny. Although these parasitoid factors are known to be responsible for host manipulation, such as immune system suppression, little is known about both identity and function of the majority of their venom components. To identify the major proteins of Toxoneuron nigriceps (Hymenoptera: Braconidae) venom, we used an integrated transcriptomic and proteomic approach. The tandem-mass spectrometric (LC-MS/MS) data combined with T. nigriceps venom gland transcriptome used as a reference database resulted in the identification of a total of thirty one different proteins. While some of the identified proteins have been described in venom from several parasitoids, others were identified for the first time. Among the identified proteins, hydrolases constituted the most abundant family followed by transferases, oxidoreductases, ligases, lyases and isomerases. The hydrolases identified in the T. nigriceps venom glands included proteases, peptidases and glycosidases, reported as common components of venom from several parasitoid species. Taken together, the identified proteins included factors that could potentially inhibit the host immune system, manipulate host physiological processes and host development, as well as provide nutrients to the parasitoid progeny, degrading host tissues by specific hydrolytic enzymes. The venom decoding provides us with information about the identity of candidate venom factors which could contribute to the success of parasitism, together with other maternal and embryonic factors.
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      PubDate: 2016-08-04T01:24:27Z
      DOI: 10.1016/j.ibmb.2016.07.001
      Issue No: Vol. 76 (2016)
  • Ingestion of the epoxide hydrolase inhibitor AUDA modulates immune
           responses of the mosquito, Culex quinquefasciatus during blood feeding
    • Authors: Jiawen Xu; Christophe Morisseau; Jun Yang; Kin Sing Stephen Lee; Shizuo G. Kamita; Bruce D. Hammock
      Pages: 62 - 69
      Abstract: Publication date: September 2016
      Source:Insect Biochemistry and Molecular Biology, Volume 76
      Author(s): Jiawen Xu, Christophe Morisseau, Jun Yang, Kin Sing Stephen Lee, Shizuo G. Kamita, Bruce D. Hammock
      Epoxide hydrolases (EHs) are enzymes that play roles in metabolizing xenobiotic epoxides from the environment, and in regulating lipid signaling molecules, such as juvenile hormones in insects and epoxy fatty acids in mammals. In this study we fed mosquitoes with an epoxide hydrolase inhibitor AUDA during artificial blood feeding, and we found the inhibitor increased the concentration of epoxy fatty acids in the midgut of female mosquitoes. We also observed ingestion of AUDA triggered early expression of defensin A, cecropin A and cecropin B2 at 6 h after blood feeding. The expression of cecropin B1 and gambicin were not changed more than two fold compared to controls. The changes in gene expression were transient possibly because more than 99% of the inhibitor was metabolized or excreted at 42 h after being ingested. The ingestion of AUDA also affected the growth of bacteria colonizing in the midgut, but did not affect mosquito longevity, fecundity and fertility in our laboratory conditions. When spiked into the blood, EpOMEs and DiHOMEs were as effective as the inhibitor AUDA in reducing the bacterial load in the midgut, while EETs rescued the effects of AUDA. Our data suggest that epoxy fatty acids from host blood are immune response regulators metabolized by epoxide hydrolases in the midgut of female mosquitoes, inhibition of which causes transient changes in immune responses, and affects growth of microbes in the midgut.
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      PubDate: 2016-08-04T01:24:27Z
      DOI: 10.1016/j.ibmb.2016.06.011
      Issue No: Vol. 76 (2016)
  • Apoptosis-related genes control autophagy and influence DENV-2 infection
           in the mosquito vector, Aedes aegypti
    • Authors: Matthew W. Eng; Madeleine N. van Zuylen; David W. Severson
      Pages: 70 - 83
      Abstract: Publication date: September 2016
      Source:Insect Biochemistry and Molecular Biology, Volume 76
      Author(s): Matthew W. Eng, Madeleine N. van Zuylen, David W. Severson
      The mosquito Aedes aegypti is the primary urban vector for dengue virus (DENV) worldwide. Insight into interactions occurring between host and pathogen is important in understanding what factors contribute to vector competence. However, many of the molecular mechanisms for vector competence remain unknown. Our previous global transcriptional analysis suggested that differential expression of apoptotic proteins is involved in determining refractoriness vs susceptibility to DENV-2 infection in Ae. aegypti females following a DENV-infected blood meal. To determine whether DENV-refractory Ae. aegypti showed more robust apoptosis upon infection, we compared numbers of apoptotic cells from midguts of refractory and susceptible strains and observed increased numbers of apoptotic cells in only the refractory strain upon DENV-2 infection. Thereafter, we manipulated apoptosis through dsRNA interference of the initiator caspase, Aedronc. Unexpectedly, dsAedronc-treated females showed both decreased frequency of disseminated infection and decreased virus titer in infected individuals. Insect caspases have also previously been identified as regulators of the cellular recycling process known as autophagy. We observed activation of autophagy in midgut and fat body tissues following a blood meal, as well as programmed activation of several apoptosis-related genes, including the effector caspase, Casps7. To determine whether autophagy was affected by caspase knockdown, we silenced Aedronc and Casps7, and observed reduced activation of autophagy upon silencing. Our results provide evidence that apoptosis-related genes are also involved in regulating autophagy, and that Aedronc may play an important role in DENV-2 infection success in Ae. aegypti, possibly through its regulation of autophagy.
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      PubDate: 2016-08-04T01:24:27Z
      DOI: 10.1016/j.ibmb.2016.07.004
      Issue No: Vol. 76 (2016)
  • Expressing a moth abcc2 gene in transgenic drosophila causes
           susceptibility to Bt Cry1Ac without requiring a cadherin-like protein
    • Authors: Tristan Stevens; Sisi Song; John B. Bruning; Amanda Choo; Simon W. Baxter
      Abstract: Publication date: Available online 30 November 2016
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Tristan Stevens, Sisi Song, John B. Bruning, Amanda Choo, Simon W. Baxter
      Bt toxins ingested by insect pests can bind to midgut receptors and cause death, although several steps in this process remain unclear. Multiple Bt toxin receptors have been identified in Lepidoptera, including a cadherin-like protein (CaLP), which is central to several models explaining Bt toxins’ mode of action. Mutations in the Plutella xylostella ATP-dependent binding cassette transporter C2 (Px-abcc2), rather than CaLP, are genetically linked with Bt Cry1Ac resistance. Here we expressed Px-abcc2 in Drosophila and performed larval bioassays to determine whether this protein acts as an effective Bt receptor. Cry1Ac had no effect on larvae expressing Px-abcc2 in salivary glands, yet larvae expressing Px-abcc2 in the midgut were highly susceptible to both Cry1Ac protoxin and trypsin activated toxin. Furthermore, the CaLP orthologue has been lost from the Drosophila genome, making this a useful system for investigating the role of CaLP peptides from Manduca sexta (CR12-MPED), which are known to act as Bt synergists in larval feeding assays. Drosophila larvae expressing Px-ABCC2 in the midgut were fed LD50 concentrations of Cry1Ac toxin or protoxin, plus purified CR12-MPED cloned from M. sexta or P. xylostella. The M. sexta CR12-MPED protein acted synergistically with Cry1Ac protoxin and activated toxin significantly more effectively than the P. xylostella peptide. This work demonstrates ABCC2 is the major functional Cry1Ac receptor for P. xylostella and the importance of CaLP proteins in Bt mode of action may vary between different lepidopteran species.
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      PubDate: 2016-12-01T01:12:45Z
      DOI: 10.1016/j.ibmb.2016.11.008
  • Cold acclimation allows Drosophila flies to maintain mitochondrial
           functioning under cold stress
    • Authors: Hervé Colinet; David Renault; Damien Roussel
      Abstract: Publication date: Available online 27 November 2016
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Hervé Colinet, David Renault, Damien Roussel
      Environmental stress generally disturbs cellular homeostasis. Researchers have hypothesized that chilling injury is linked to a shortage of ATP. However, previous studies conducted on insects exposed to nonfreezing low temperatures presented conflicting results. In this study, we investigated the mitochondrial bioenergetics of Drosophila melanogaster flies exposed to chronic cold stress (4 °C). We assessed mitochondrial oxygen consumption while monitoring the rate of ATP synthesis at various times (0, 1, 2, and 3 days) during prolonged cold stress and at two assay temperatures (25 and 4 °C). We compared organelle responses between cold-susceptible and cold-acclimated phenotypes. Continuous exposure to low temperature provoked temporal declines in the rates of mitochondrial respiration and ATP synthesis. Respiratory control ratios (RCRs) suggested that mitochondria were not critically uncoupled. Nevertheless, after 3 days of continuous cold stress, a sharp decline in the mitochondrial ATP synthesis rate was observed in control flies when they were assayed at low temperature. This change was associated with reduced survival capacity in control flies. In contrast, cold-acclimated flies exhibited high survival and maintained higher rates of mitochondrial ATP synthesis and coupling (i.e., higher RCRs). Adaptive changes due to cold acclimation observed in the whole organism were thus manifested in isolated mitochondria. Our observations suggest that cold tolerance is linked to the ability to maintain bioenergetics capacity under cold stress.
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      PubDate: 2016-12-01T01:12:45Z
      DOI: 10.1016/j.ibmb.2016.11.007
  • The DNA chaperone HMGB1 potentiates the transcriptional activity of Rel1A
           in the mosquito Aedes aegypti
    • Authors: Anderson de Mendonça Amarante; Natapong Jupatanakul; Isabel Caetano de Abreu da Silva; Vitor Coutinho Carneiro; Amanda Roberta Revoredo Vicentino; George Dimopolous; Octávio Augusto C. Talyuli; Marcelo Rosado Fantappié
      Abstract: Publication date: Available online 17 November 2016
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Anderson de Mendonça Amarante, Natapong Jupatanakul, Isabel Caetano de Abreu da Silva, Vitor Coutinho Carneiro, Amanda Roberta Revoredo Vicentino, George Dimopolous, Octávio Augusto C. Talyuli, Marcelo Rosado Fantappié
      High Mobility Group protein 1 (HMGB1) is a non-histone, chromatin-associated nuclear protein that functions in regulating eukaryotic gene expression. We investigated the influence and mechanism of action of Aedes aegypti HMGB1 (AaHMGB1) on mosquito Rel1A-mediated transcription from target gene promoters. The DNA-binding domain (RHD) of AaRel1A was bacterially expressed and purified, and AaHMGB1 dramatically enhanced RHD binding to consensus NF-kB/Rel DNA response elements. Luciferase reporter analyses using a cecropin gene promoter showed that AaHMGB1 potentiates the transcriptional activity of AaRel1A in Aag-2 cells. Moreover, overexpression of AaHMGB1 in Aag-2 cells led to an increase in mRNA levels of antimicrobial peptide genes. In vitro GST pull-down assays revealed that the presence of DNA is a pre-requisite for assembly of a possible ternary complex containing DNA, AaHMGB1 and AaRel1A. Notably, DNA bending by AaHMGB1 enhanced the binding of AaRel1A to a DNA fragment containing a putative NF-kB/Rel response element. Importantly, AaHMGB1 was identified as a potential immune modulator in A. aegypti through AaHMGB1 overexpression or RNAi silencing in Aag-2 cells followed by bacterial challenge or through AaHMGB1 RNAi knockdown in mosquitoes followed by Dengue virus (DENV) infection. We propose a model in which AaHMGB1 bends NF-kB/Rel target DNA to recruit and allow more efficient AaRel1A binding to activate transcription of effector genes, culminating in a stronger Toll pathway-mediated response against DENV infection.
      Graphical abstract image

      PubDate: 2016-11-23T17:04:24Z
      DOI: 10.1016/j.ibmb.2016.11.006
  • Sexually dimorphic traits in the silkworm, Bombyx mori, are regulated by
    • Authors: Jun Xu; Shuai Zhan; Shuqing Chen; Baosheng Zeng; Zhiqian Li; Anthony A. James; Anjiang Tan; Yongping Huang
      Abstract: Publication date: Available online 17 November 2016
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Jun Xu, Shuai Zhan, Shuqing Chen, Baosheng Zeng, Zhiqian Li, Anthony A. James, Anjiang Tan, Yongping Huang
      The DM domain genes, doublesex (dsx) in insects, or their structural homologs, male abnormal 3 (mab-3) in nematodes and Dmrt1 (doublesex and mab-3-related transcription factor 1) in mammals, are downstream regulators of the sex determination pathway that control sexually dimorphic development. Despite the functional importance of dsx and its potential applications in sterile insect technologies (SITs), the mechanisms by which it controls sexually dimorphic traits and the subsequent developmental gene networks in insects are poorly understood. Phylogenetic analyses indicate that insect dsx genes have sex-specific alternative splicing isoforms, whereas other taxa do not. We exploited genome editing and transgenesis technologies to induce mutations in either the male-specific isoform (dsx M ) or common region (dsx C ) of dsx in the somatic tissues of the lepidopteran model insect Bombyx mori. Disruptions of gene function produced either male-specific sexually-dimorphic defects or intersexual phenotypes; these results differ from those observed in other insects, including Drosophila melanogaster. Our data provide insights into the divergence of the insect sex determination pathways related to the most conserved downstream component dsx.
      Graphical abstract image

      PubDate: 2016-11-23T17:04:24Z
      DOI: 10.1016/j.ibmb.2016.11.005
  • Ryanodine receptor point mutations confer diamide insecticide resistance
           in tomato leafminer, Tuta absoluta (Lepidoptera: Gelechiidae)
    • Authors: Emmanouil Roditakis; Denise Steinbach; Gerald Moritz; Emmanouil Vasakis; Marianna Stavrakaki; Aris Ilias; Lidia García-Vidal; María del Rosario Martínez-Aguirre; Pablo Bielza; Evangelia Morou; Jefferson E. Silva; Wellington M. Silva; Ηerbert Siqueira; Sofia Iqbal; Bartlomiej J. Troczka; Martin Williamson; Chris Bass; Anastasia Tsagkarakou; John Vontas; Ralf Nauen
      Abstract: Publication date: Available online 12 November 2016
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Emmanouil Roditakis, Denise Steinbach, Gerald Moritz, Emmanouil Vasakis, Marianna Stavrakaki, Aris Ilias, Lidia García-Vidal, María del Rosario Martínez-Aguirre, Pablo Bielza, Evangelia Morou, Jefferson E. Silva, Wellington M. Silva, Ηerbert Siqueira, Sofia Iqbal, Bartlomiej J. Troczka, Martin Williamson, Chris Bass, Anastasia Tsagkarakou, John Vontas, Ralf Nauen
      Insect ryanodine receptors (RyR) are the molecular target-site for the recently introduced diamide insecticides. Diamides are particularly active on Lepidoptera pests, including tomato leafminer, Tuta absoluta (Lepidoptera: Gelechiidae). High levels of diamide resistance were recently described in some European populations of T. absoluta, however, the mechanisms of resistance remained unknown. In this study the molecular basis of diamide resistance was investigated in a diamide resistant strain from Italy (IT-GELA-SD4), and additional resistant field populations collected in Greece, Spain and Brazil. The genetics of resistance was investigated by reciprocally crossing strain IT-GELA-SD4 with a susceptible strain and revealed an autosomal incompletely recessive mode of inheritance. To investigate the possible role of target-site mutations as known from diamondback moth (Plutella xylostella), we sequenced respective domains of the RyR gene of T. absoluta. Genotyping of individuals of IT-GELA-SD4 and field-collected strains showing different levels of diamide resistance revealed the presence of G4903E and I4746M RyR target-site mutations. These amino acid substitutions correspond to those recently described for diamide resistant diamondback moth, i.e. G4946E and I4790M. We also detected two novel mutations, G4903V and I4746T, in some of the resistant T. absoluta strains. Radioligand binding studies with thoracic membrane preparations of the IT-GELA-SD4 strain provided functional evidence that these mutations alter the affinity of the RyR to diamides. In combination with previous work on P. xylostella our study highlights the importance of position G4903 (G4946 in P. xylostella) of the insect RyR in defining sensitivity to diamides. The discovery of diamide resistance mutations in T. absoluta populations of diverse geographic origin has serious implications for the efficacy of diamides under applied conditions. The implementation of appropriate resistance management strategies is strongly advised to delay the further spread of resistance.
      Graphical abstract image

      PubDate: 2016-11-16T16:39:07Z
      DOI: 10.1016/j.ibmb.2016.11.003
  • Heparan sulfate/heparin glycosaminoglycan binding alters inhibitory
           profile and enhances anticoagulant function of conserved Amblyomma
           americanum tick saliva serpin 19
    • Authors: Albert Mulenga
      Abstract: Publication date: Available online 12 November 2016
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Željko M. Radulović, Albert Mulenga
      Some serine protease inhibitor (serpin) regulators of essential life pathways bind glycosaminoglycans (GAGs) to enhance inhibitory functions and achieve physiologically relevant rates. This study demonstrates that highly conserved Amblyomma americanum tick saliva serpin 19 (AAS19), a broad-spectrum inhibitor of hemostasis and inflammation system proteases and anticoagulant, can bind heparan sulfate/heparin (HS)GAGs and that this interaction alters its function. Substrate hydrolysis and unpaired t-test analyses revealed that HSGAG binding caused rAAS19 inhibitory activity to: (i) significantly increase against blood clotting factors (f) IIa (thrombin) and fIXa, (ii) significantly reduce against fXa and fXIIa and (iii) moderate to no effect against trypsin, kallikrein, papain, and plasmin. Stoichiometry of inhibition (SI) analyses show that HSGAG binding improved the rAAS19 inhibitory efficiency against thrombin 2.7–4.3 folds as revealed by SI of 13.19 in absence of HSGAGs to 4.83–3.04 in their presence. Our data show that HSGAG binding dramatically enhanced rAAS19 anticoagulant function. In the recalcification time assay, rAAS19 pre-incubated with HSGAGs prior to the assay, delayed plasma clotting by an additional 176–457 s above HSGAGs or rAAS19 alone. Our data suggest that formation of the HSGAGs and rAAS19 complex is important for the observed enhanced anticoagulant effect. Delay of plasma clotting was higher when HSGAGs and rAAS19 were co-incubated to allow complex formation prior to blood clotting assay as opposed to no co-incubation. We have discussed our finding with reference to tick feeding physiology and utility of the rAAS19 in blood clotting disorder therapy.
      Graphical abstract image

      PubDate: 2016-11-16T16:39:07Z
  • Comparative transcriptome analysis of chemosensory genes in two sister
           leaf beetles provides insights into chemosensory speciation
    • Authors: Bin Zhang; Wei Zhang; Rui-E. Nie; Wen-Zhu Li; Kari A. Segraves; Xing-Ke Yang; Huai-Jun Xue
      Abstract: Publication date: Available online 9 November 2016
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Bin Zhang, Wei Zhang, Rui-E. Nie, Wen-Zhu Li, Kari A. Segraves, Xing-Ke Yang, Huai-Jun Xue
      Divergence in chemosensory traits has been posited as an important component of chemosensory speciation in insects. In particular, chemosensory genes expressed in the peripheral sensory neurons are likely to influence insect behaviors such as preference for food, oviposition sites, and mates. Despite their key role in insect behavior and potentially speciation, the underlying genetic basis for divergence in chemosensory traits remains largely unexplored. One way to ascertain the role of chemosensory genes in speciation is to make comparisons of these genes across closely related species to detect the genetic signatures of divergence. Here, we used high throughput transcriptome analysis to compare chemosensory genes of the sister leaf beetles species Pyrrhalta maculicollis and P. aenescens, whose sexual isolation and host plant preference are mediated by divergent chemical signals. Although there was low overall divergence between transcriptome profiles, there were a number of genes that were differentially expressed between the species. Furthermore, we also detected two chemosensory genes under positive selection, one of which that was also differentially expressed between the species, suggesting a possible role for these genes in chemical-based premating reproductive isolation and host use. Combined with the available chemical and ecological work in this system, further studies of the divergent chemosensory genes presented here will provide insight into the process of chemosensory speciation among Pyrrhalta beetles.
      Graphical abstract image

      PubDate: 2016-11-09T16:20:09Z
      DOI: 10.1016/j.ibmb.2016.11.001
  • Arylalkylamine N-acetyltransferase 1 gene (TcAANAT1) is required for
           cuticle morphology and pigmentation of the adult red flour beetle,
           Tribolium castaneum
    • Authors: Mi Young Noh; Bonwoo Koo; Karl J. Kramer; Subbaratnam Muthukrishnan; Yasuyuki Arakane
      Abstract: Publication date: Available online 2 November 2016
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Mi Young Noh, Bonwoo Koo, Karl J. Kramer, Subbaratnam Muthukrishnan, Yasuyuki Arakane
      In the insect cuticle tanning pathway (sclerotization and pigmentation), the enzyme arylalkylamine N-acetyltransferase (AANAT) catalyzes the acetylation of dopamine to form N-acetyldopamine (NADA), which is one of the major precursors for quinone-mediated tanning. In this study we characterized and investigated the function of TcAANAT1 in cuticle pigmentation of the red flour beetle, Tribolium castaneum. We isolated a full length TcAANAT1 cDNA that encodes a protein of 256 amino acid residues with a predicted GCN5-related acetyltransferase domain containing an acetyl-CoA binding motif. TcAANAT1 transcripts were detected at all stages of development with lowest expressions at the embryonic and pharate pupal stages. We expressed and purified the encoded recombinant TcAANAT1 protein (rTcAANAT1) that exhibited highest activity at slightly basic pH values (for example, pH 7.5 to 8.5 using dopamine as the substrate). In addition, rTcAANAT1 acts on a wide range substrates including tryptamine, octopamine and norepinephrine with similar substrate affinities with K m values in the range of 0.05–0.11 mM except for tyramine (K m  = 0.56 mM). Loss of function of TcAANAT1 caused by RNAi had no effect on larval and pupal development. The tanning of pupal setae, gin traps and urogomphi proceeded normally. However, the resulting adults (∼70%) exhibited a roughened exoskeletal surface, separated elytra and improperly folded hindwings. The body wall, elytra and veins of the hindwing of the mature adults were significantly darker than those of control insects probably due to the accumulation of dopamine melanin. A dark pigmentation surrounding the bristles located on the inter-veins of the elytron was evident primarily because of the underlying darkly pigmented trabeculae that partition the dorsal and ventral layers of the elytron. These results support the hypothesis that TcAANAT1 acetylates dopamine and plays a role in development of the morphology and pigmentation of T. castaneum adult cuticle.
      Graphical abstract image

      PubDate: 2016-11-09T16:20:09Z
      DOI: 10.1016/j.ibmb.2016.10.013
  • Prophenoloxidase activation and antimicrobial peptide expression induced
           by the recombinant microbe binding protein of Manduca sexta
    • Authors: Yang Wang; Haobo Jiang
      Abstract: Publication date: Available online 29 October 2016
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Yang Wang, Haobo Jiang
      Manduca sexta microbe binding protein (MBP) is a member of the β-1,3-glucanase-related protein superfamily that includes Gram-negative bacteria-binding proteins (GNBPs), β-1,3-glucan recognition proteins (βGRPs), and β-1,3-glucanases. Our previous and current studies showed that the purified MBP from baculovirus-infected insect cells had stimulated prophenoloxidase (proPO) activation in the hemolymph of naïve and immune challenged larvae and that supplementation of the exogenous MBP and peptidoglycans (PGs) had caused synergistic increases in PO activity. To explore the underlying mechanism, we separated by SDS-PAGE naïve and induced larval plasma treated with buffer or MBP and detected on immunoblots changes in intensity and/or mobility of hemolymph (serine) proteases [HP14, HP21, HP6, HP8, proPO-activating proteases (PAPs) 1–3] and their homologs (SPH1, SPH2). In a nickel pull-down assay, we observed association of MBP with proHP14 (slightly), βGRP2, PG recognition protein-1 (PGRP1, indirectly), SPH1, SPH2, and proPO2. Further experiments indicated that diaminopimelic acid (DAP) or Lys PG, MBP, PGRP1, and proHP14 together trigger the proPO activation system in a Ca2+-dependent manner. Injection of the recombinant MBP into the 5th instar naïve larvae significantly induced the expression of several antimicrobial peptide genes, revealing a possible link between HP14 and immune signal transduction. Together, these results suggest that the recognition of Gram-negative or -positive bacteria via their PGs induces the melanization and Toll pathways in M. sexta.
      Graphical abstract image

      PubDate: 2016-11-02T15:10:10Z
      DOI: 10.1016/j.ibmb.2016.10.006
  • CRISPR/Cas9 in locusts: Successful establishment of an olfactory
           deficiency line by targeting the mutagenesis of an odorant receptor
           co-receptor (Orco)
    • Authors: Yan Li; Jie Zhang; Dafeng Chen; Pengcheng Yang; Feng Jiang; Xianhui Wang; Le Kang
      Abstract: Publication date: Available online 12 October 2016
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Yan Li, Jie Zhang, Dafeng Chen, Pengcheng Yang, Feng Jiang, Xianhui Wang, Le Kang
      Locusts are important agricultural pests worldwide and regarded as study models for entomology. However, the absence of targeted gene manipulation systems for locusts has restricted their applications for research. Herein, we report the successful use of the CRISPR/Cas9 system to induce a targeted heritable mutagenesis of the migratory locust, Locusta migratoria. The target sequence of gRNA was designed to disrupt the gene encoding the odorant receptor co-receptor (Orco) and examine the roles of the odorant receptor pathway in the locust. Microinjection of the mixture of Cas9-mRNA and Orco-gRNA into the locust eggs resulted in efficient target-gene editing at a rate of 71.7% in G0 animals and achieved a germline efficiency of up to 88.1% in G1 animals. By a crossing strategy, we successfully established stable Orco mutant lines. EAGs and SSRs indicated that the fourth-instar nymphs of the Orco mutants showed severely impaired electrophysiological responses to multiple odors. The Orco mutant locusts lost an attraction response to aggregation pheromones under the crowding conditions. The locomotor activity and body coloration of the Orco mutant locusts did not significantly differ from those of the two other genotypes. This study provides an easy and effective approach by using the CRISPR/Cas9 system for generating loss-of-function mutants for functional genetic studies of locusts and for managing insect pests.
      Graphical abstract image

      PubDate: 2016-10-14T11:50:29Z
      DOI: 10.1016/j.ibmb.2016.10.003
  • Proteomic analysis of castor bean tick Ixodes ricinus: A focus on
           chemosensory organs
    • Authors: Immacolata Iovinella; Liping Ban Limei Song Paolo Pelosi Francesca Romana
      Abstract: Publication date: Available online 29 September 2016
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Immacolata Iovinella, Liping Ban, Limei Song, Paolo Pelosi, Francesca Romana Dani
      In arthropods, the large majority of studies on olfaction have been focused on insects, where most of the proteins involved have been identified. In particular, chemosensing in insects relies on two families of membrane receptors, olfactory/gustatory receptors (ORs/GRs) and ionotropic receptors (IRs), and two classes of soluble proteins, odorant-binding proteins (OBPs) and chemosensory proteins (CSPs). In other arthropods, such as ticks and mites, only IRs have been identified, while genes encoding for OBPs and CSPs are absent. A third class of soluble proteins, called Niemann-Pick C2 (NPC2) has been suggested as potential carrier for semiochemicals both in insects and other arthropods. Here we report the results of a proteomic analysis on olfactory organs (Haller's organ and palps) and control tissues of the tick Ixodes ricinus, and of immunostaining experiments targeting NPC2s. Adopting different extraction and proteomic approaches, we identified a large number of proteins, and highlighted those differentially expressed. None of the 13 NPC2s known for this species was found. On the other hand, using immunocytochemistry, we detected reaction against one NPC2 in the Haller's organ and palp sensilla. We hypothesised that the low concentration of such proteins in the tick's tissues could possibly explain the discrepant results. In ligand-binding assays the corresponding recombinant NPC2 showed good affinity to the fluorescent probe N-phenylnaphthylamine and to few organic compounds, supporting a putative role of NPC2s as odorant carriers.
      Graphical abstract image

      PubDate: 2016-10-01T00:48:47Z
  • Gossypol toxicity and detoxification in Helicoverpa armigera and Heliothis
    • Authors: Corinna Krempl; Hanna M. Heidel-Fischer; Guillermo Hugo Jiménez-Alemán; Michael Reichelt; Riya Christina Menezes; Wilhelm Boland; Heiko Vogel; David G. Heckel; Nicole Joußen
      Abstract: Publication date: Available online 26 September 2016
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Corinna Krempl, Hanna M. Heidel-Fischer, Guillermo Hugo Jiménez-Alemán, Michael Reichelt, Riya Christina Menezes, Wilhelm Boland, Heiko Vogel, David G. Heckel, Nicole Joußen
      Gossypol is a polyphenolic secondary metabolite produced by cotton plants, which is toxic to many organisms. Gossypol's aldehyde groups are especially reactive, forming Schiff bases with amino acids of proteins and cross-linking them, inhibiting enzyme activities and contributing to toxicity. Very little is known about gossypol's mode of action and its detoxification in cotton-feeding insects that can tolerate certain concentrations of this compound. Here, we tested the toxicity of gossypol and a gossypol derivative lacking free aldehyde groups (SB-gossypol) toward Helicoverpa armigera and Heliothis virescens, two important pests on cotton plants. Larval feeding studies with these two species on artificial diet supplemented with gossypol or SB-gossypol revealed no detectable toxicity of gossypol, when the aldehyde groups were absent. A cytochrome P450 enzyme, CYP6AE14, is upregulated in H. armigera feeding on gossypol, and has been claimed to directly detoxify gossypol. However, using in vitro assays with heterologously expressed CYP6AE14, no metabolites of gossypol were detected, and further studies suggest that gossypol is not a direct substrate of CYP6AE14. Furthermore, larvae feeding on many other plant toxins also upregulate CYP6AE14. Our data demonstrate that the aldehyde groups are critical for the toxicity of gossypol when ingested by H. armigera and H. virescens larvae, and suggest that CYP6AE14 is not directly involved in gossypol metabolism, but may play a role in the general stress response of H. armigera larvae toward plant toxins.
      Graphical abstract image

      PubDate: 2016-10-01T00:48:47Z
      DOI: 10.1016/j.ibmb.2016.09.003
  • RNA interference in the Colorado potato beetle, Leptinotarsa decemlineata:
           Identification of key contributors
    • Authors: June-Sun Yoon; Jayendra Shukla; Zhong Jun Gong; Kanakachari Mogilicherla; Subba Reddy Palli
      Abstract: Publication date: Available online 26 September 2016
      Source:Insect Biochemistry and Molecular Biology
      Author(s): June-Sun Yoon, Jayendra Shukla, Zhong Jun Gong, Kanakachari Mogilicherla, Subba Reddy Palli
      RNA interference (RNAi) is a useful reverse genetics tool for investigation of gene function as well as for practical applications in many fields including medicine and agriculture. RNAi works very well in coleopteran insects including the Colorado potato beetle (CPB), Leptinotarsa decemlineata. We used a cell line (Lepd-SL1) developed from CPB to identify genes that play key roles in RNAi. We screened 50 genes with potential functions in RNAi by exposing Lepd-SL1 cells to dsRNA targeting one of the potential RNAi pathway genes followed by incubation with dsRNA targeting inhibitor of apoptosis (IAP, silencing of this gene induces apoptosis). Out of 50 genes tested, silencing of 29 genes showed an effect on RNAi. Silencing of five genes (Argonaute-1, Argonaute-2a, Argonaute-2b, Aubergine and V-ATPase 16 kDa subunit 1, Vha16) blocked RNAi suggesting that these genes are essential for functioning of RNAi in Lepd-SL1 cells. Interestingly, Argonaute-1 and Aubergine are known to function in miRNA and piRNA pathway respectively are also critical to siRNA pathway. Using 32P labeled dsRNA, we showed that these miRNA and piRNA Argonautes but not Argonaute-2 is required for processing of dsRNA to siRNA. Transfection of pIZT/V5 constructs containing these five genes into Sf9 cells (the cells where RNAi does not work well) showed that expression of all genes tested, except the Argonaute-2a, improved RNAi in these cells. Results from Vha16 gene silencing and bafilomycin-A1 treatment suggest that endosomal escape plays an important role in dsRNA-mediated RNAi in Lepd-SL1 cells.
      Graphical abstract image

      PubDate: 2016-10-01T00:48:47Z
      DOI: 10.1016/j.ibmb.2016.09.002
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