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  Subjects -> BIOLOGY (Total: 2998 journals)
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BIOCHEMISTRY (236 journals)                  1 2 | Last

Showing 1 - 200 of 236 Journals sorted alphabetically
AAPS PharmSciTech     Hybrid Journal   (Followers: 6)
Acetic Acid Bacteria     Open Access   (Followers: 2)
ACS Central Science     Open Access   (Followers: 8)
ACS Chemical Biology     Full-text available via subscription   (Followers: 261)
ACS Chemical Neuroscience     Full-text available via subscription   (Followers: 18)
Acta Biochimica Polonica     Open Access  
Acta Crystallographica Section D : Biological Crystallography     Hybrid Journal   (Followers: 9)
Acta Crystallographica Section F: Structural Biology Communications     Hybrid Journal   (Followers: 8)
Advances and Applications in Bioinformatics and Chemistry     Open Access   (Followers: 10)
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: 8)
Advances in Protein Chemistry and Structural Biology     Full-text available via subscription   (Followers: 20)
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: 9)
American Journal of Biochemistry and Biotechnology     Open Access   (Followers: 66)
American Journal of Biochemistry and Molecular Biology     Open Access   (Followers: 15)
American Journal of Polymer Science     Open Access   (Followers: 26)
Amino Acids     Hybrid Journal   (Followers: 8)
Analytical and Bioanalytical Chemistry Research     Open Access  
Analytical Biochemistry     Hybrid Journal   (Followers: 166)
Angiogenesis     Hybrid Journal   (Followers: 3)
Annals of Clinical Biochemistry     Hybrid Journal   (Followers: 8)
Annual Review of Biochemistry     Full-text available via subscription   (Followers: 55)
Annual Review of Chemical and Biomolecular Engineering     Full-text available via subscription   (Followers: 12)
Applied Biochemistry and Biotechnology     Hybrid Journal   (Followers: 44)
Applied Biochemistry and Microbiology     Hybrid Journal   (Followers: 17)
Applied Organometallic Chemistry     Hybrid Journal   (Followers: 7)
Archives of Biochemistry and Biophysics     Hybrid Journal   (Followers: 20)
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)
Bangladesh Journal of Medical Biochemistry     Open Access   (Followers: 3)
BBA Clinical     Open Access  
BBR : Biochemistry and Biotechnology Reports     Open Access   (Followers: 4)
Biocatalysis     Open Access  
Biochemical and Biophysical Research Communications     Hybrid Journal   (Followers: 22)
Biochemical and Molecular Medicine     Full-text available via subscription   (Followers: 4)
Biochemical Compounds     Open Access  
Biochemical Engineering Journal     Hybrid Journal   (Followers: 15)
Biochemical Genetics     Hybrid Journal   (Followers: 3)
Biochemical Journal     Full-text available via subscription   (Followers: 25)
Biochemical Pharmacology     Hybrid Journal   (Followers: 10)
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: 314)
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     Hybrid Journal   (Followers: 14)
Biochemistry and Molecular Biology Education     Hybrid Journal   (Followers: 6)
Biochemistry and Molecular Biology of Fishes     Full-text available via subscription   (Followers: 1)
Biochemistry Research International     Open Access   (Followers: 6)
Biochimica et Biophysica Acta (BBA) - Molecular and Cell Biology of Lipids     Hybrid Journal   (Followers: 7)
Biochimica et Biophysica Acta (BBA) - Molecular Basis of Disease     Hybrid Journal   (Followers: 14)
Biochimica et Biophysica Acta (BBA) - Molecular Cell Research     Hybrid Journal   (Followers: 9)
Biochimie     Hybrid Journal   (Followers: 7)
Biochimie Open     Open Access  
Bioconjugate Chemistry     Full-text available via subscription   (Followers: 30)
BioDrugs     Full-text available via subscription   (Followers: 7)
Bioelectrochemistry     Hybrid Journal   (Followers: 2)
Biofuels     Hybrid Journal   (Followers: 11)
Biogeochemistry     Hybrid Journal   (Followers: 14)
BioInorganic Reaction Mechanisms     Hybrid Journal   (Followers: 1)
Biokemistri     Open Access  
Biological Chemistry     Partially Free   (Followers: 22)
Biomaterials Research     Open Access   (Followers: 4)
Biomedicines     Open Access   (Followers: 1)
BioMolecular Concepts     Hybrid Journal   (Followers: 2)
Bioscience, Biotechnology, and Biochemistry     Hybrid Journal   (Followers: 24)
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: 8)
Cell Biochemistry and Biophysics     Hybrid Journal   (Followers: 6)
Cell Biochemistry and Function     Hybrid Journal   (Followers: 6)
Cellular Physiology and Biochemistry     Open Access   (Followers: 3)
ChemBioChem     Hybrid Journal   (Followers: 7)
Chemical and Biological Technologies for Agriculture     Open Access  
Chemical Biology & Drug Design     Hybrid Journal   (Followers: 20)
Chemical Engineering Journal     Hybrid Journal   (Followers: 46)
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: 6)
Chemistry & Biology     Full-text available via subscription   (Followers: 30)
Chemistry and Ecology     Hybrid Journal  
ChemTexts     Hybrid Journal  
Clinica Chimica Acta     Hybrid Journal   (Followers: 33)
Clinical Biochemist Reviews     Full-text available via subscription   (Followers: 1)
Clinical Biochemistry     Hybrid Journal   (Followers: 18)
Clinical Chemistry     Full-text available via subscription   (Followers: 68)
Clinical Chemistry and Laboratory Medicine     Hybrid Journal   (Followers: 61)
Clinical Lipidology     Full-text available via subscription   (Followers: 1)
Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology     Hybrid Journal   (Followers: 4)
Comparative Biochemistry and Physiology Part B: Biochemistry and Molecular Biology     Hybrid Journal   (Followers: 1)
Comparative Biochemistry and Physiology Part C: Toxicology & Pharmacology     Hybrid Journal   (Followers: 7)
Comparative Biochemistry and Physiology Part D: Genomics and Proteomics     Hybrid Journal   (Followers: 2)
Comprehensive Biochemistry     Full-text available via subscription   (Followers: 1)
Computational Biology and Chemistry     Hybrid Journal   (Followers: 12)
Critical Reviews in Biochemistry and Molecular Biology     Hybrid Journal   (Followers: 5)
Current Chemical Biology     Hybrid Journal   (Followers: 2)
Current Medicinal Chemistry     Hybrid Journal   (Followers: 16)
Current Opinion in Chemical Biology     Hybrid Journal   (Followers: 28)
Current Opinion in Lipidology     Hybrid Journal   (Followers: 6)
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: 56)
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: 4)
Frontiers in Molecular Biosciences     Open Access   (Followers: 2)
Frontiers in Natural Product Chemistry     Hybrid Journal  
Global Biogeochemical Cycles     Full-text available via subscription   (Followers: 15)
Green Chemistry     Full-text available via subscription   (Followers: 11)
Histochemistry and Cell Biology     Hybrid Journal   (Followers: 5)
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: 8)
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   (Followers: 1)
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: 4)
Journal of Microbial & Biochemical Technology     Open Access   (Followers: 2)
Journal of Applied Biology & Biotechnology     Open Access   (Followers: 2)
Journal of Bioactive and Compatible Polymers     Hybrid Journal   (Followers: 3)
Journal of Biochemistry     Hybrid Journal   (Followers: 43)
Journal of Biochemistry and Molecular Biology Research     Open Access  
Journal of Biological Chemistry     Full-text available via subscription   (Followers: 206)
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: 3)
Journal of Chemical Neuroanatomy     Hybrid Journal  
Journal of Clinical Lipidology     Hybrid Journal   (Followers: 2)
Journal of Comparative Physiology B : Biochemical, Systemic, and Environmental Physiology     Hybrid Journal   (Followers: 4)
Journal of Drug Discovery and Therapeutics     Open Access  
Journal of Enzyme Inhibition and Medicinal Chemistry     Open Access   (Followers: 3)
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: 5)
Journal of Inborn Errors of Metabolism and Screening     Open Access  
Journal of Inorganic Biochemistry     Hybrid Journal   (Followers: 7)
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: 4)
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: 7)
Journal of Steroid Biochemistry and Molecular Biology     Hybrid Journal   (Followers: 2)
Journal of Virology & Antiviral Research     Hybrid Journal   (Followers: 5)
Journal of Wood Chemistry and Technology     Hybrid Journal   (Followers: 10)
La Rivista Italiana della Medicina di Laboratorio - Italian Journal of Laboratory Medicine     Hybrid Journal  
Lab on a Chip     Full-text available via subscription   (Followers: 36)
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: 6)
Molecular Aspects of Medicine     Hybrid Journal   (Followers: 3)
Molecular Informatics     Hybrid Journal   (Followers: 6)
Molecular inhibitors in targeted therapy     Open Access  
Moscow University Chemistry Bulletin     Hybrid Journal   (Followers: 1)
Mycologia     Hybrid Journal  
Mycology : An International Journal on Fungal Biology     Hybrid Journal   (Followers: 5)
Natural Products and Bioprospecting     Open Access   (Followers: 2)
Nature Chemical Biology     Full-text available via subscription   (Followers: 73)
Nature Communications     Open Access   (Followers: 202)
Neurosignals     Open Access  
NOVA     Open Access  
Novelty in Biomedicine     Open Access  
OA Biochemistry     Open Access   (Followers: 1)
OA Inflammation     Open Access  
Ocean Acidification     Open Access   (Followers: 4)
Organic & Biomolecular Chemistry     Full-text available via subscription   (Followers: 87)

        1 2 | Last

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  [3089 journals]
  • DNA methylation affects the lifespan of honey bee (Apis mellifera L.)
           workers – Evidence for a regulatory module that involves vitellogenin
           expression but is independent of juvenile hormone function
    • Authors: Carlos A.M. Cardoso-Júnior; Karina R. Guidugli-Lazzarini; Klaus Hartfelder
      Pages: 21 - 29
      Abstract: Publication date: January 2018
      Source:Insect Biochemistry and Molecular Biology, Volume 92
      Author(s): Carlos A.M. Cardoso-Júnior, Karina R. Guidugli-Lazzarini, Klaus Hartfelder
      The canonic regulatory module for lifespan of honey bee (Apis mellifera) workers involves a mutual repressor relationship between juvenile hormone (JH) and vitellogenin (Vg). Compared to vertebrates, however, little is known about a possible role of epigenetic factors. The full genomic repertoire of DNA methyltransferases (DNMTs) makes the honey bee an attractive emergent model for studying the role of epigenetics in the aging process of invertebrates, and especially so in social insects. We first quantified the transcript levels of the four DNMTs encoding genes in the head thorax and abdomens of workers of different age, showing that dnmt1a and dnmt3 expression is up-regulated in abdomens of old workers, whereas dnmt1b and dnmt2 are down-regulated in heads of old workers. Pharmacological genome demethylation by RG108 treatment caused an increase in worker lifespan. Next, we showed that the genomic DNA methylation status indirectly affects vitellogenin gene expression both in vitro and in vivo in young workers, and that this occurs independent of caloric restriction or JH levels, suggesting that a non-canonical circuitry may be acting in parallel with the JH/Vg module to regulate the adult life cycle of honey bee workers. Our data provide evidence that epigenetic factors play a role in regulatory networks associated with complex life history traits of a social insect.
      Graphical abstract image

      PubDate: 2017-12-07T13:22:28Z
      DOI: 10.1016/j.ibmb.2017.11.005
      Issue No: Vol. 92 (2017)
       
  • Upregulation of Aedes aegypti Vago1 by Wolbachia and its effect on dengue
           virus replication
    • Authors: Sultan Asad; Rhys Parry; Sassan Asgari
      Pages: 45 - 52
      Abstract: Publication date: January 2018
      Source:Insect Biochemistry and Molecular Biology, Volume 92
      Author(s): Sultan Asad, Rhys Parry, Sassan Asgari
      Dengue infection along with its related disease conditions poses a significant threat to human health. The pathogen responsible for this infection is dengue virus (DENV) which is primarily transmitted to humans through the bites of Aedes aegypti mosquitoes. Unavailability of a potent vaccine has recently sparked renewed research endeavours aimed at vector control. To date, Wolbachia as an endosymbiotic bacterium has shown promise as a novel biocontrol agent to restrict DENV replication in the vector, although the underlying antiviral mechanism remains elusive. Recent studies have demonstrated the potential role of Vago as a novel secretory protein involved in cross-talk between the innate immune pathways in Culex quinquefasciatus mosquitoes to restrict West Nile virus replication. In this study, we have identified two homologs of the Vago protein in Ae. aegypti and looked into their modulation in the case of Wolbachia wMelPop strain infection. Furthermore, we have investigated the role of AeVago1, that is highly induced by Wolbachia, in the context of Wolbachia-mosquito-DENV interactions. Knockdown studies of the AeVago1 gene in Wolbachia-infected cells led to significant increases in DENV replication, with no effect on Wolbachia density. Our results suggest that the Wolbachia-induced AeVago1 in Ae. aegypti may function as a host factor to suppress DENV replication in the mosquito.
      Graphical abstract image

      PubDate: 2017-12-07T13:22:28Z
      DOI: 10.1016/j.ibmb.2017.11.008
      Issue No: Vol. 92 (2017)
       
  • 20-Hydroxyecdysone promotes release of GBP-binding protein from
           oenocytoids to suppress hemocytic encapsulation
    • Authors: Xiao-Rong Zhuo; Lei Chen; Gui-Jie Wang; Xu-Sheng Liu; Yu-Feng Wang; Ke Liu; Xiao-Qiang Yu; Jia-Lin Wang
      Pages: 53 - 64
      Abstract: Publication date: January 2018
      Source:Insect Biochemistry and Molecular Biology, Volume 92
      Author(s): Xiao-Rong Zhuo, Lei Chen, Gui-Jie Wang, Xu-Sheng Liu, Yu-Feng Wang, Ke Liu, Xiao-Qiang Yu, Jia-Lin Wang
      Growth-blocking peptide (GBP) is an insect cytokine that stimulates plasmatocyte adhesion, thereby playing a critical role in encapsulation reaction. It has been previously demonstrated that GBP-binding protein (GBPB) is released upon oenocytoid lysis in response to GBP and is responsible for subsequent clearance of GBP from hemolymph. However, current knowledge about GBPB is limited and the mechanism by which insects increase GBPB levels to inactivate GBP remains largely unexplored. Here, we have identified one GBP precursor (HaGBP precursor) gene and two GBPB (namely HaGBPB1 and HaGBPB2) genes from the cotton bollworm, Helicoverpa armigera. The HaGBP precursor was found to be predominantly expressed in fat body, whereas HaGBPB1 and HaGBPB2 were mainly expressed in hemocytes. Immunological analyses indicated that both HaGBPB1 and HaGBPB2 are released from hemocytes into the plasma during the wandering stage. Additionally, 20-hydroxyecdysone (20E) treatment or bead challenge could promote the release of HaGBPB1 and HaGBPB2 at least partly from oenocytoids into the plasma. Furthermore, we demonstrate that the N-terminus of HaGBPB1 is responsible for binding to HaGBP and suppresses HaGBP-induced plasmatocyte spreading and encapsulation. Overall, this study helps to enrich our understanding of the molecular mechanism underlying 20E mediated regulation of plasmatocyte adhesion and encapsulation via GBP-GBPB interaction.
      Graphical abstract image

      PubDate: 2017-12-07T13:22:28Z
      DOI: 10.1016/j.ibmb.2017.11.006
      Issue No: Vol. 92 (2017)
       
  • Bombyx ortholog of the Drosophila eye color gene brown controls riboflavin
           transport in Malpighian tubules
    • Authors: Haokun Zhang; Takashi Kiuchi; Chikara Hirayama; Susumu Katsuma; Toru Shimada
      Pages: 65 - 72
      Abstract: Publication date: January 2018
      Source:Insect Biochemistry and Molecular Biology, Volume 92
      Author(s): Haokun Zhang, Takashi Kiuchi, Chikara Hirayama, Susumu Katsuma, Toru Shimada
      The Drosophila eye color gene brown is known to control the transport of pteridine precursors in adult eyes. The Brown protein belongs to the ATP-binding cassette (ABC) transporter G family, which includes proteins encoded by the genes brown, scarlet, and white. These genes are responsible for pigmentation in Drosophila and the domestic silkworm Bombyx mori. Although orthologs of brown are conserved among insects, the function of this gene is only known in Drosophila. Here, we elucidated the function of the B. mori ortholog Bm-brown. We examined the spatial and temporal expression profiles of Bm-brown and found that this gene was specifically and continuously expressed in larval Malpighian tubules (MTs), indicating this gene has a special function in MTs. We then successfully obtained a Bm-brown knockout (KO) strain based on a wild-type (WT) strain using the clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated nuclease 9 (Cas9) system. We found that larval MTs of the KO strain were white, whereas those of WT were yellow. It is known that larval yellow MTs of WT are due to the accumulation of riboflavin. Therefore, we compared the riboflavin contents of MTs of KO and WT strains, and found that the riboflavin level in the KO strain was 20 fold less than that in WT during the 5th instar period. MTs are known to exhibit a similar milky color in w-3 mutant larvae due to a deficiency of riboflavin accumulation. The responsible gene for w-3 mutant is the Bmwh3 gene, which is orthologous to Drosophila white. Thus, we speculate that Bm-brown is heterodimerized with Bmwh3, similar to Brown/White in Drosophila, and acts as a riboflavin transporter in silkworm MTs.
      Graphical abstract image

      PubDate: 2017-12-07T13:22:28Z
      DOI: 10.1016/j.ibmb.2017.11.012
      Issue No: Vol. 92 (2017)
       
  • Crystal structure of ryanodine receptor N-terminal domain from Plutella
           xylostella reveals two potential species-specific insecticide-targeting
           sites
    • Authors: Lianyun Lin; Chen Liu; Juan Qin; Jie Wang; Shengjie Dong; Wei Chen; Weiyi He; Qingzhi Gao; Minsheng You; Zhiguang Yuchi
      Pages: 73 - 83
      Abstract: Publication date: January 2018
      Source:Insect Biochemistry and Molecular Biology, Volume 92
      Author(s): Lianyun Lin, Chen Liu, Juan Qin, Jie Wang, Shengjie Dong, Wei Chen, Weiyi He, Qingzhi Gao, Minsheng You, Zhiguang Yuchi
      Ryanodine receptors (RyRs) are large calcium-release channels located in sarcoplasmic reticulum membrane. They play a central role in excitation-contraction coupling of muscle cells. Three commercialized insecticides targeting pest RyRs generate worldwide sales over 2 billion U.S. dollars annually, but the structure of insect RyRs remains elusive, hindering our understanding of the mode of action of RyR-targeting insecticides and the development of insecticide resistance in pests. Here we present the crystal structure of RyR N-terminal domain (NTD) (residue 1–205) at 2.84 Å resolution from the diamondback moth (DBM), Plutella xylostella, a destructive pest devouring cruciferous crops all over the world. Similar to its mammalian homolog, DBM RyR NTD consists of a beta-trefoil folding motif and a flanking alpha helix. Interestingly, two regions in NTD interacting with neighboring domains showed distinguished conformations in DBM relative to mammalian RyRs. Using homology modeling and molecular dynamics simulation, we created a structural model of the N-terminal three domains, showing two unique binding pockets that could be targeted by potential species-specific insecticides. Thermal melt experiment showed that the stability of DBM RyR NTD was higher than mammalian RyRs, probably due to a stable intra-domain disulfide bond observed in the crystal structure. Previously DBM NTD was shown to be one of the two critical regions to interact with insecticide flubendiamide, but isothermal titration calorimetry experiments negated DBM NTD alone as a major binding site for flubendiamide.
      Graphical abstract image

      PubDate: 2017-12-07T13:22:28Z
      DOI: 10.1016/j.ibmb.2017.11.009
      Issue No: Vol. 92 (2017)
       
  • Development and ultrastructure of the rigid dorsal and flexible ventral
           cuticles of the elytron of the red flour beetle, Tribolium castaneum
    • Authors: Mi Young Noh; Subbaratnam Muthukrishnan; Karl J. Kramer; Yasuyuki Arakane
      Pages: 21 - 33
      Abstract: Publication date: December 2017
      Source:Insect Biochemistry and Molecular Biology, Volume 91
      Author(s): Mi Young Noh, Subbaratnam Muthukrishnan, Karl J. Kramer, Yasuyuki Arakane
      Insect exoskeletons are composed of the cuticle, a biomaterial primarily formed from the linear and relatively rigid polysaccharide, chitin, and structural proteins. This extracellular material serves both as a skin and skeleton, protecting insects from environmental stresses and mechanical damage. Despite its rather limited compositional palette, cuticles in different anatomical regions or developmental stages exhibit remarkably diverse physicochemical and mechanical properties because of differences in chemical composition, molecular interactions and morphological architecture of the various layers and sublayers throughout the cuticle including the envelope, epicuticle and procuticle (exocuticle and endocuticle). Even though the ultrastructure of the arthropod cuticle has been studied rather extensively, its temporal developmental pattern, in particular, the synchronous development of the functional layers in different cuticles during a molt, is not well understood. The beetle elytron, which is a highly modified and sclerotized forewing, offers excellent advantages for such a study because it can be easily isolated at precise time points during development. In this study, we describe the morphogenesis of the dorsal and ventral cuticles of the elytron of the red flour beetle, Tribolium castaneum, during the period from the 0 d-old pupa to the 9 d-old adult. The deposition of exocuticle and mesocuticle is substantially different in the two cuticles. The dorsal cuticle is four-fold thicker than the ventral. Unlike the ventral cuticle, the dorsal contains a thicker exocuticle consisting of a large number of horizontal laminae and vertical pore canals with pore canal fibers and rib-like veins and bristles as well as a mesocuticle, lying right above the enodcuticle. The degree of sclerotization appears to be much greater in the dorsal cuticle. All of these differences result in a relatively thick and tanned rigid dorsal cuticle and a much thinner and less pigmented membrane-like ventral cuticle.
      Graphical abstract image

      PubDate: 2017-11-09T11:48:23Z
      DOI: 10.1016/j.ibmb.2017.11.003
      Issue No: Vol. 91 (2017)
       
  • Serpin-9 and -13 regulate hemolymph proteases during immune responses of
           Manduca sexta
    • Authors: Yan He; Yang Wang; Picheng Zhao; Subrahmanyam Rayaprolu; Xiuhong Wang; Xiaolong Cao; Haobo Jiang
      Pages: 71 - 81
      Abstract: Publication date: November 2017
      Source:Insect Biochemistry and Molecular Biology, Volume 90
      Author(s): Yan He, Yang Wang, Picheng Zhao, Subrahmanyam Rayaprolu, Xiuhong Wang, Xiaolong Cao, Haobo Jiang
      Serpins are a superfamily of proteins, most of which inhibit cognate serine proteases by forming inactive acyl-enzyme complexes. In the tobacco hornworm Manduca sexta, serpin-1, -3 through -7 negatively regulate a hemolymph serine protease system that activates precursors of the serine protease homologs (SPHs), phenoloxidases (POs), Spätzles, and other cytokines. Here we report the cloning and characterization of M. sexta serpin-9 and -13. Serpin-9, a 402-residue protein most similar to Drosophila Spn77Ba, has R366 at the P1 position right before the cleavage site; Serpin-13, a 444-residue ortholog of Drosophila Spn28Dc, is longer than the other seven serpins and has R410 as the P1 residue. Both serpins are mainly produced in fat body and secreted into plasma to function. While their mRNA and protein levels were not up-regulated upon immune challenge, they blocked protease activities and affected proPO activation in hemolymph. Serpin-9 inhibited human neutrophil elastase, cathepsin G, trypsin, and chymotrypsin to different extents; serpin-13 reduced trypsin activity to approximately 10% at a molar ratio of 4:1 (serpin: enzyme). Serpin-9 was cleaved at Arg366 by the enzymes with different specificity, but serpin-13 had four P1 sites (Arg410 for trypsin-like proteases, Gly406 and Ala409 for the elastase and Thr404 for cathepsin G). Supplementation of induced cell-free hemolymph (IP, P for plasma) with recombinant serpin-9 did not noticeably affect proPO activation, but slightly reduced the PO activity increase after 0–50% ammonium sulfate fraction of the IP had been elicited by bacteria. In comparison, addition of recombinant serpin-13 significantly inhibited proPO activation in IP and the suppression was stronger in the fraction of IP. Serpin-9- and -13-containing protein complexes were isolated from IP using their antibodies. Hemolymph protease-1 precursor (proHP1), HP6 and HP8 were found to be associated with serpin-9, whereas proHP1, HP2 and HP6 were pulled downed with serpin-13. These results indicate that both serpins regulate immune proteases in hemolymph of M. sexta larvae.
      Graphical abstract image

      PubDate: 2017-10-14T08:17:32Z
      DOI: 10.1016/j.ibmb.2017.09.015
      Issue No: Vol. 90 (2017)
       
  • Timed Knickkopf function is essential for wing cuticle formation in
           Drosophila melanogaster
    • Authors: Kaixia Li; Xubo Zhang; Ying Zuo; Weimin Liu; Jianzhen Zhang; Bernard Moussian
      Pages: 1 - 10
      Abstract: Publication date: October 2017
      Source:Insect Biochemistry and Molecular Biology, Volume 89
      Author(s): Kaixia Li, Xubo Zhang, Ying Zuo, Weimin Liu, Jianzhen Zhang, Bernard Moussian
      The insect cuticle is an extracellular matrix that consists of the polysaccharide chitin, proteins, lipids and organic molecules that are arranged in distinct horizontal layers. In Drosophila melanogaster, these layers are not formed sequentially, but, at least partially, at the same time. Timing of the underlying molecular mechanisms is conceivably crucial for cuticle formation. To study this issue, we determined the time period during which the function of Knickkopf (Knk), a key factor of chitin organization, is required for wing cuticle differentiation in D. melanogaster. Although knk is expressed throughout metamorphosis, we demonstrate that its expression 30 h prior and 48 h after pupariation is essential for correct wing cuticle formation. In other words, expression beyond this period is futile. Importantly, manipulation of Knk expression during this time causes wing bending suggesting an effect of Knk amounts on the physical properties of the wing cuticle. Manipulation of Knk expression also interferes with the structure and function of the cuticle surface. First, we show that the shape of surface nano-structures depends on the expression levels of knk. Second, we find that cuticle impermeability is compromised in wings with reduced knk expression. In summary, despite the extended supply of Knk during metamorphosis, controlled amounts of Knk are important for correct wing cuticle differentiation and function in a concise period of time.
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      PubDate: 2017-08-25T17:51:06Z
      DOI: 10.1016/j.ibmb.2017.08.003
      Issue No: Vol. 89 (2017)
       
  • Active subsite properties, subsite residues and targeting to lysosomes or
           midgut lumen of cathepsins L from the beetle Tenebrio molitor
    • Authors: Ticiane F. Damasceno; Renata O. Dias; Juliana R. de Oliveira; Roberto K. Salinas; Maria A. Juliano; Clelia Ferreira; Walter R. Terra
      Pages: 17 - 30
      Abstract: Publication date: October 2017
      Source:Insect Biochemistry and Molecular Biology, Volume 89
      Author(s): Ticiane F. Damasceno, Renata O. Dias, Juliana R. de Oliveira, Roberto K. Salinas, Maria A. Juliano, Clelia Ferreira, Walter R. Terra
      Cathepsins L are the major digestive peptidases in the beetle Tenebrio molitor. Two digestive cathepsins L (TmCAL2 and TmCAL3) from it had their 3D structures solved. The aim of this paper was to study in details TmCAL3 specificity and properties and relate them to its 3D structure. Recombinant TmCAL3 was assayed with 64 oligopeptides with different amino acid replacements in positions P2, P1, P1′ and P2'. Results showed that TmCAL3 S2 specificity differs from the human enzyme and that its specificities also explain why on autoactivation two propeptide residues remain in the enzyme. Data on free energy of binding and of activation showed that S1 and S2′ are mainly involved in substrate binding, S1′ acts in substrate binding and catalysis, whereas S2 is implied mainly in catalysis. Enzyme subsite residues were identified by docking with the same oligopeptide used for kinetics. The subsite hydrophobicities were calculated from the efficiency of hydrolysis of different amino acid replacements in the peptide and from docking data. The results were closer for S1 and S2′ than for S1' and S2, indicating that the residue subsites that were more involved in transition state binding are different from those binding the substrate seen in docking. Besides TmCAL1-3, there are nine other cathepsins L, most of them more expressed at midgut. They are supposed to be directed to lysosomes by a Drosophila-like Lerp receptor and/or motifs in their prodomains. The mannose 6-phosphate lysosomal sorting machinery is absent from T. molitor transcriptome. Cathepsin L direction to midgut contents seems to depend on overexpression.
      Graphical abstract image

      PubDate: 2017-09-03T19:53:40Z
      DOI: 10.1016/j.ibmb.2017.08.004
      Issue No: Vol. 89 (2017)
       
  • TmSR-C, scavenger receptor class C, plays a pivotal role in antifungal and
           antibacterial immunity in the coleopteran insect Tenebrio molitor
    • Authors: Soo Gon Kim; Yong Hun Jo; Jeong Hwan Seong; Ki Beom Park; Mi Young Noh; Jun Ho Cho; Hye Jin Ko; Chang Eun Kim; Hamisi Tindwa; Bharat Bhusan Patnaik; In Seok Bang; Yong Seok Lee; Yeon Soo Han
      Pages: 31 - 42
      Abstract: Publication date: Available online 1 September 2017
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Soo Gon Kim, Yong Hun Jo, Jeong Hwan Seong, Ki Beom Park, Mi Young Noh, Jun Ho Cho, Hye Jin Ko, Chang Eun Kim, Hamisi Tindwa, Bharat Bhusan Patnaik, In-Seok Bang, Yong Seok Lee, Yeon Soo Han
      Scavenger receptors (SRs) constitute a family of membrane-bound receptors that bind to multiple ligands. The SR family of proteins is involved in removing cellular debris, oxidized low-density lipoproteins, and pathogens. Specifically, class C scavenger receptors (SR-C) have also been reported to be involved in phagocytosis of gram-positive and -negative bacteria in Drosophila and viruses in shrimp. However, reports are unavailable regarding the role of SR-C in antifungal immune mechanisms in insects. In this study, a full-length Tenebrio molitor SR-C (TmSR-C) sequence was obtained by 5′- and 3′-Rapid amplification of cDNA ends-polymerase chain reaction (RACE-PCR). The TmSR-C full-length cDNA comprised 1671 bp with 5′- and 3′-untranslated regions of 23- and 107-bp, respectively. TmSR-C encodes a putative protein of 556 amino acid residues that is constitutively expressed in all tissues of late instar larvae and 2-day-old adults, with the highest transcript levels observed in hemocytes of larvae and adults. TmSR-C mRNA showed a 2.5-fold and 3-fold increase at 24 and 6 h after infection with Candida albicans and β-glucan, respectively. Immunoassay with TmSR-C polyclonal antibody showed induction of the putative protein in the cytosols of hemocytes at 3 h after inoculation of C. albicans. RNA interference (RNAi)-based gene silencing and phagocytosis assays were used to understand the role of TmSR-C in antifungal immunity. Silencing of TmSR-C transcripts reduced the survivability of late instar larvae at 2 days post-inoculation of C. albicans, Escherichia coli, or Staphylococcus aureus. Furthermore, in TmSR-C-silenced larvae, there was a decline in the rate of microorganism phagocytosis. Taken together, results of this study suggest that TmSR-C plays a pivotal role in phagocytosing not only fungi but also gram-negative and -positive bacteria in T. molitor.
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      PubDate: 2017-09-03T19:53:40Z
      DOI: 10.1016/j.ibmb.2017.08.007
      Issue No: Vol. 89 (2017)
       
  • FOXA transcriptional factor modulates insect susceptibility to Bacillus
           thuringiensis Cry1Ac toxin by regulating the expression of toxin-receptor
           ABCC2 and ABCC3 genes
    • Authors: Jianghuai Li; Yuemin Ma; Wanli Yuan; Yutao Xiao; Chenxi Liu; Jia Wang; Jianxin Peng; Rong Peng; Mario Soberón; Alejandra Bravo; Yongbo Yang; Kaiyu Liu
      Pages: 1 - 11
      Abstract: Publication date: Available online 21 July 2017
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Jianghuai Li, Yuemin Ma, Wanli Yuan, Yutao Xiao, Chenxi Liu, Jia Wang, Jianxin Peng, Rong Peng, Mario Soberón, Alejandra Bravo, Yongbo Yang, Kaiyu Liu
      Cry toxins produced by Bacillus thuringiensis (Bt) are insecticidal proteins widely used in insect control. Recently, it was shown that ATP-binding cassette transporter proteins (ABC) such as ABCC2, ABCC3, ABCG1 and ABCA2 are implicated in the insecticidal action of Cry toxins as putative receptors. However, the transcriptional regulators involved in the expression of ABC transporter genes remain unknown. Sequence analysis of promoter regions of ABCC2 gene from Helicoverpa armigera and ABCC3 gene from Spodoptera litura Sl-HP cultured cells, revealed the potential participation of Forkhead box protein A (FOXA), a transcription factor that regulates the expression of genes through remodeling chromatin. To determine if FOXA was involved in regulating expression of ABCC2 and ABCC3 genes, the expression of FOXA, ABCC2 and ABCC3 was compared in Sl-HP cells that are sensitive to Cry1Ac toxin with those on S. frugiperda Sf9 cells that are not sensitive to the toxin. Expression levels of those genes were significantly higher in Sl-HP than in Sf9 cells. Transient expression of FOXA in Sf9 cells activated ABCC2 and ABCC3 transcription, which directly correlated with enhanced Cry1Ac-susceptibility in these cells. Silencing of FOXA gene expression by RNAi in H. armigera larvae resulted in a decreased expression of ABCC2 and ABCC3 without affecting expression of other Cry toxin receptor genes such as alkaline phosphatase, aminopeptidase or cadherin. Silencing of FOXA gene expression also resulted in a Cry1Ac-tolerant phenotype since lower mortality and higher pupation rate were observed in diet containing Cry1Ac protoxin in comparison with the control group. These results demonstrate that FOXA up-regulates expression of the Cry1Ac-toxin receptor ABCC2 and ABCC3 genes, and that lower FOXA expression correlates with tolerance to Cry toxin in cell lines and in lepidopteran larvae.
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      PubDate: 2017-07-26T13:33:28Z
      DOI: 10.1016/j.ibmb.2017.07.004
      Issue No: Vol. 88 (2017)
       
  • CRISPR/Cas9-mediated knockout of two eye pigmentation genes in the brown
           planthopper, Nilaparvata lugens (Hemiptera: Delphacidae)
    • Abstract: Publication date: Available online 11 December 2017
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Wen-Hua Xue, Nan Xu, Xiao-Bo Yuan, Hao-Hao Chen, Jin-Li Zhang, Sheng-Jie Fu, Chuan-Xi Zhang, Hai-Jun Xu
      The brown planthopper Nilaparvata lugens is one of the most destructive insect pests in Asia, demonstrating high fertility and causing huge crop losses by sucking sap of rice as well as transmitting viruses. However, functional genomic studies on N. lugens are seriously constrained by lack of genetic tools. Here, we employed two eye pigmentation genes to generate germ-line mutations in N. lugens using the CRISPR/Cas9 (clustered regularly interspaced palindromic repeats/CRISPR-associated) system. We showed that injection of single guide RNA of the cinnabar gene of N. lugens (Nl-cn) into pre-blastoderm eggs induced insertion and deletion (indels) in the founder generation (G0), which were heritably transmitted to the following G1 generation, leading to bright red compound eyes and ocelli. Mutations of N. lugens white (Nl-w) generated a high mutant rate of up to 27.3%, resulting in mosaic eyes consisting of white and lightly pigmented ommatidia in both G0 and G1 individuals. The specificity of CRISPR/Cas9-mediated mutagenesis was further bolstered by PCR and RNA interference-based knockdown analysis. These results show that CRISPR/Cas9-mediated gene editing is achievable in a hemipteran insect, offering a valuable tool for the study of functional genomics and pest management in this planthopper species.
      Graphical abstract image

      PubDate: 2017-12-12T14:04:16Z
       
  • Receptor protein of Lysinibacillus sphaericus mosquito-larvicidal toxin
           displays amylomaltase activity
    • Abstract: Publication date: Available online 8 December 2017
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Mahima Sharma, Gagan D. Gupta, Vinay Kumar
      The activated binary toxin (BinAB) from Lysinibacillus sphaericus binds to surface receptor protein (Cqm1) on the midgut cell membrane and kills Culex quinquefasciatus larvae on internalization. Cqm1 is attached to cells via a glycosyl-phosphatidylinositol (GPI) anchor. It has been classified as a member of glycoside hydrolase family 13 of the CAZy database. Here, we report characterization of the ordered domain (residues 23–560) of Cqm1. Gene expressing Cqm1 of BinAB susceptible mosquito was chemically synthesized and the protein was purified using E. coli expression system. Values for the Michaelis-Menten kinetics parameters towards 4-nitrophenyl α-D-glucopyranoside (α-pNPG) substrate were estimated to be 0.44 mM (Km) and 1.9 s−1 (kcat). Thin layer chromatography experiments established Cqm1 as α-glucosidase competent to cleave α-1,4-glycosidic bonds of maltose and maltotriose with high glycosyltransferase activity to form glucose-oligomers. The observed hydrolysis and synthesis of glucose-oligomers is consistent with open and accessible active-site in the structural model. The protein also hydrolyses glycogen and sucrose. These activities suggest that Cqm1 may be involved in carbohydrate metabolism in mosquitoes. Further, toxic BinA component does not inhibit α-glucosidase activity of Cqm1, while BinB reduced the activity by nearly 50%. The surface plasmon resonance study reveals strong binding of BinB with Cqm1 (Kd, 9.8 nM). BinA interaction with Cqm1 however, is 1000-fold weaker. Notably the estimated Kd values match well with dissociation constants reported earlier with larvae brush border membrane fractions. The Cqm1 protein forms a stable dimer that is consistent with its apical localization in lipid rafts. Its melting temperature (Tm) as observed by thermofluor-shift assay is 51.5 °C and Ca2+ provides structural stability to the protein.
      Graphical abstract image

      PubDate: 2017-12-12T14:04:16Z
       
  • Species specific RNA A-to-I editing of mosquito RDL modulates GABA potency
           and influences agonistic, potentiating and antagonistic actions of
           ivermectin
    • Authors: Jennina Taylor-Wells; Anish Senan; Isabel Bermudez; Andrew K. Jones
      Abstract: Publication date: Available online 6 December 2017
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Jennina Taylor-Wells, Anish Senan, Isabel Bermudez, Andrew K. Jones
      The insect GABA receptor, RDL, is the target of several classes of pesticides. The peptide sequences of RDL are generally highly conserved between diverse insects. However, RNA A-to-I editing can effectively alter amino acid residues of RDL in a species specific manner, which can affect the potency of GABA and possibly insecticides. We report here that RNA A-to-I editing alters the gene products of Rdl in three mosquito disease vectors, recoding five amino acid residues in RDL of Aedes aegypti and six residues in RDLs of Anopheles gambiae and Culex pipiens, which is the highest extent of editing in RDL observed to date. Analysis of An. gambiae Rdl cDNA sequences identified 24 editing isoforms demonstrating a considerable increase in gene product diversity. RNA editing influenced the potency of the neurotransmitter, GABA, on An. gambiae RDL editing isoforms expressed in Xenopus laevis oocytes, as demonstrated by EC50s ranging from 5 ± 1 to 246 ± 41 μM. Fipronil showed similar potency on different editing isoforms, with IC50s ranging from 0.18 ± 0.08 to 0.43 ± 0.09 μM. In contrast, editing of An. gambiae RDL affected the activating, potentiating and inhibiting actions of ivermectin. For example, ivermectin potentiated currents induced by GABA at the EC20 concentration in the unedited isoform but not in the fully edited variant. Editing of a residue in the first transmembrane domain or the cys-loop influenced this potentiation, highlighting residues involved in the allosteric mechanisms of cys-loop ligand-gated ion channels. Understanding the interactions of ivermectin with molecular targets may have relevance to mosquito control in areas where people are administered with ivermectin to treat parasitic diseases.
      Graphical abstract image

      PubDate: 2017-12-07T13:22:28Z
      DOI: 10.1016/j.ibmb.2017.12.001
       
  • Structural characterization of a lepidopteran type-II farnesyl diphosphate
           synthase from the spruce budworm, Choristoneura fumiferana: Implications
           for inhibitor design
    • Authors: Marie-Ève Picard; Audrey Nisole; Catherine Béliveau; Stephanie Sen; Aline Barbar; Rong Shi; Michel Cusson
      Abstract: Publication date: Available online 26 November 2017
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Marie-Ève Picard, Audrey Nisole, Catherine Béliveau, Stephanie Sen, Aline Barbar, Rong Shi, Michel Cusson
      Farnesyl diphosphate synthase (FPPS) is an enzyme from the class of short chain (E)-prenyltransferases that catalyzes the condensation of two molecules of isopentenyl diphosphate (IPP, C5) with dimethylallyl diphosphate (DMAPP, C5) to generate the C15 product FPP. In insects, FPPS plays a key role in the biosynthesis of the morphogenetic and gonadotropic “juvenile hormone” (JH). Lepidopteran genomes encode two very distinct FPPS paralogs, one of which (“type-II”) is expressed almost exclusively in the JH-producing glands, the corpora allata. This paralog has been hypothesized to display structural features that enable the binding of the bulkier precursors required for the biosynthesis of lepidopteran ethyl-branched JHs. Here, we report on the first crystal structures of an insect FPPS solved to date. Apo, ligand-bound, and inhibitor-bound structures of type-II FPPS (FPPS2) from the spruce budworm, Choristoneura fumiferana (Order: Lepidoptera), were obtained. Comparison of apo and inhibitor-bound enzymes revealed differences in both inhibitor binding and structural plasticity of CfFPPS2 compared to other FPPSs. Our data showed that IPP is not essential to the closure of the C-terminal tail. Ortho-substituted pyridinium bisphosphonates, previously shown to inhibit CfFPPS2, bound to the allylic site, as predicted; however, their alkyl groups were oriented towards the homoallylic binding site, with the bulkier propyl-substituted inhibitor penetrating deeply into the IPP binding pocket. The current study sheds light on the structural basis of substrate specificity of type-II FPPS of the spruce budworm. Through a comparison with other inhibitor-bound FPPSs, we propose several approaches to improve inhibitor selectivity and potency.
      Graphical abstract image

      PubDate: 2017-12-07T13:22:28Z
      DOI: 10.1016/j.ibmb.2017.11.011
       
  • Enhanced heat tolerance in transgenic silkworm via overexpression of
           Pyrococcus furiosus superoxide reductase
    • Authors: Liang Jiang; Chunlin Huang; Bingbing Wang; Huizhen Guo; Qiang Sun; Fei Xia; Guowen Xu; Qingyou Xia
      Abstract: Publication date: Available online 21 November 2017
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Liang Jiang, Chunlin Huang, Bingbing Wang, Huizhen Guo, Qiang Sun, Fei Xia, Guowen Xu, Qingyou Xia
      Heat shock causes a serious harm to organisms by accelerating the production of reactive oxygen species (ROS). Pyrococcus furiosus superoxide reductase (PfSOR) is an enzyme that efficiently detoxifies ROS. In order to generate a silkworm strain with high heat tolerance for sericulture, we synthesized an artificial DNA sequence encoding PfSOR based on the codon bias of Bombyx mori. PfSOR was successfully overexpressed in transgenic silkworm (named A4SOR) and BmE cells, as determined by RT-PCR and western blot analyses. An SOR activity assay confirmed that the expressed enzyme was functional in A4SOR. After exposure to a temperature of 35 °C for 44 h, the mortality rate was about 30% lower in transgenic A4SOR than in non-transgenic silkworms. Moreover, transgene expression had no apparent effect on economic characteristics of silkworms. The heat tolerance of silkworm was thus enhanced by expressing an archaeal SOR; this can be useful for sericulture in regions where the average temperature exceeds the optimal environmental temperature for B. mori of 25 °C.
      Graphical abstract image

      PubDate: 2017-12-07T13:22:28Z
      DOI: 10.1016/j.ibmb.2017.11.010
       
  • Carboxylesterase genes in pyrethroid resistant house flies, Musca
           domestica
    • Authors: Xuechun Feng; Ming Li; Nannan Liu
      Abstract: Publication date: Available online 14 November 2017
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Xuechun Feng, Ming Li, Nannan Liu
      Carboxylesterases are one of the major enzyme families involved in the detoxification of pyrethroids. Up-regulation of carboxylesterase genes is thought to be a major component of insecticide resistant mechanisms in insects. Based on the house fly transcriptome and genome database, a total of 39 carboxylesterase genes of different functional clades have been identified in house flies. In this study, eleven of these genes were found to be significantly overexpressed in the resistant ALHF house fly strain compared with susceptible aabys and wild-type CS strains. Eight up-regulated carboxylesterase genes with their expression levels were further induced to a higher level in response to permethrin treatments, indicating that constitutive and inductive overexpression of carboxylesterase are co-responsible for the enhanced detoxification of insecticides. Spatial expression studies revealed these up-regulated genes to be abundantly distributed in fat bodies and genetically mapped on autosome 2 or 3 of house flies, and their expression could be regulated by factors on autosome 1, 2 and 5. Taken together, these results demonstrate that multiple carboxylesterase genes are co-upregulated in resistant house flies, providing further evidence for their involvement in the detoxification of insecticides and development of insecticide resistance.
      Graphical abstract image

      PubDate: 2017-11-16T13:53:32Z
      DOI: 10.1016/j.ibmb.2017.11.007
       
  • Inhibition of the complement system by saliva of Anopheles (Nyssorhynchus)
           aquasalis
    • Authors: Antonio Ferreira Mendes-Sousa; Vladimir Fazito Vale; Daniel Costa Queiroz; Adalberto Alves Pereira-Filho; Naylene Carvalho Sales da Silva; Leonardo Barbosa Koerich; Luciano Andrade Moreira; Marcos Horácio Pereira; Maurício Roberto Sant’Anna; Ricardo Nascimento Araújo; John Andersen; Jesus Gilberto Valenzuela; Nelder Figueiredo Gontijo
      Abstract: Publication date: Available online 8 November 2017
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Antonio Ferreira Mendes-Sousa, Vladimir Fazito Vale, Daniel Costa Queiroz, Adalberto Alves Pereira-Filho, Naylene Carvalho Sales da Silva, Leonardo Barbosa Koerich, Luciano Andrade Moreira, Marcos Horácio Pereira, Maurício Roberto Sant’Anna, Ricardo Nascimento Araújo, John Andersen, Jesus Gilberto Valenzuela, Nelder Figueiredo Gontijo
      Anopheline mosquitoes are vectors of malaria parasites. Their saliva contains anti-hemostatic and immune-modulator molecules that favor blood feeding and parasite transmission. In this study, we describe the inhibition of the alternative pathway of the complement system (AP) by Anopheles aquasalis salivary gland extracts (SGE). According to our results, the inhibitor present in SGE acts on the initial step of the AP blocking deposition of C3b on the activation surfaces. Properdin, which is a positive regulatory molecule of the AP, binds to SGE. When SGE was treated with an excess of properdin, it was unable to inhibit the AP. Through SDS-PAGE analysis, A. aquasalis presented a salivary protein with the same molecular weight as recombinant complement inhibitors belonging to the SG7 family described in the saliva of other anopheline species. At least some SG7 proteins bind to properdin and are AP inhibitors. Searching for SG7 proteins in the A. aquasalis genome, we retrieved a salivary protein that shared an 85% identity with albicin, which is the salivary alternative pathway inhibitor from A. albimanus. This A. aquasalis sequence was also very similar (81% ID) to the SG7 protein from A. darlingi, which is also an AP inhibitor. Our results suggest that the salivary complement inhibitor from A. aquasalis is an SG7 protein that can inhibit the AP by binding to properdin and abrogating its stabilizing activity. Albicin, which is the SG7 from A. albimanus, can directly inhibit AP convertase. Given the high similarity of SG7 proteins, the SG7 from A. aquasalis may also directly inhibit AP convertase in the absence of properdin.
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      PubDate: 2017-11-09T11:48:23Z
      DOI: 10.1016/j.ibmb.2017.11.004
       
  • Nuclear receptor HR3 controls locust molt by regulating chitin synthesis
           and degradation genes of Locusta migratoria
    • Authors: Xiaoming Zhao; Zhongyu Qin; Weimin Liu; Xiaojian Liu; Bernard Moussian; Enbo Ma; Sheng Li; Jianzhen Zhang
      Abstract: Publication date: Available online 4 November 2017
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Xiaoming Zhao, Zhongyu Qin, Weimin Liu, Xiaojian Liu, Bernard Moussian, Enbo Ma, Sheng Li, Jianzhen Zhang
      During growth and development of insects, the steroid hormone 20-Hydroxyecdysone (20E) regulates the molting process through activation of a series of genes including E74, E75 and HR3 by the 20E receptor EcR. Here, we analyzed the function of LmHR3 in the migratory locust Locusta migratoria. By sequence comparison, we first identified and characterized the putative nuclear receptor protein (LmHR3) based on L. migratoria transcriptome data. The full length cDNA is 2272 bp long encoding a protein of 455 amino acids that contains a DNA binding domain (zinc finger) and a ligand binding domain. Phylogenetic analyses showed that LmHR3 has a high homology with the ortholog from Blattaria. RT-qPCR results revealed that LmHR3 has a low level expression in the early days of 5th instar nymphs, and then increases and peaks at day 6, followed by a decrease to low levels before ecdysis. The LmHR3, hence, coincides with the profile of circulating 20E levels. Indeed, we show that transcription of LmHR3 is induced by 20E in vivo, and significantly suppressed by successfully knocking down expression of LmEcR. After injection of dsRNA for LmHR3 (dsLmHR3) at day 2 of earlier instar nymphs (3rd and 4th instar) and final instar nymphs (5th instar), none of the nymphs were able to molt normally, and eventually died. Chitin staining and ultra-structural analysis showed that both the synthesis of the new cuticle and the degradation of the old cuticle were blocked in the dsLmHR3 treated nymphs. Especially, chitin synthesis genes (LmUAP1 and LmCHS1) and chitinase genes (LmCHT5 and LmCHT10) were significantly down-regulated in the dsLmHR3 treatment group. Together, our results suggest that LmHR3 is involved in the control of chitin synthesis and degradation during L. migratoria molting.
      Graphical abstract image

      PubDate: 2017-11-09T11:48:23Z
      DOI: 10.1016/j.ibmb.2017.11.001
       
  • The role of a single gene encoding the Single von Willebrand factor
           C-domain protein (SVC) in bumblebee immunity extends beyond antiviral
           defense
    • Authors: Haidong Wang; Guy Smagghe; Ivan Meeus
      Abstract: Publication date: Available online 23 October 2017
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Haidong Wang, Guy Smagghe, Ivan Meeus
      The Single von Willebrand factor C-domain proteins (SVCs) are a group of short proteins mainly found in arthropods. They are proposed to be responsive in relation to environmental challenges including the nutritional status, bacterial and viral infections. The SVC protein Vago acts as a cross-talk molecule between the small interfering RNA (siRNA) pathway and the Jak/STAT pathway upon viral infection in Drosophila melanogaster and Culex mosquito cells. Unlike flies and mosquitoes that possess diverse SVCs, most bee species only have one of which the function remains unclear. Here we investigated whether this single SVC within the genome of the bumblebee Bombus terrestris is also involved in the host antiviral immunity and whether links with other immune pathways can be found. We can show the presence of two key characteristics of Vago linked with BtSVC in bumblebees. The antiviral character is proven by silencing BtSVC, which lead to increased Israeli acute paralysis virus (IAPV) levels in the fat body. Second, the silencing of BtDicer-2 resulted in a lower expression of BtSVC and increased IAPV levels, confirming the link between Dicer-2 and BtSVC. We were, however, unable to demonstrate a third known role of Vago in the activation of the Jak/STAT pathway. This is probably because we lack good markers for this pathway in bumblebees. Interestingly, we found that BtSVC contributes to the basal expression levels of four antimicrobial peptide (AMP)-coding genes in the fat body of the bumblebees. Therefore, the single SVC gene in bumblebees may be involved in both host antiviral immunity and basal AMPs expression.
      Graphical abstract image

      PubDate: 2017-10-26T05:16:53Z
      DOI: 10.1016/j.ibmb.2017.10.002
       
  • Describing the role of Drosophila melanogaster ABC transporters in
           insecticide biology using CRISPR-Cas9 knockouts
    • Authors: Shane Denecke; Roberto Fusetto; Philip Batterham
      Abstract: Publication date: Available online 20 October 2017
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Shane Denecke, Roberto Fusetto, Philip Batterham
      ABC transporters have a well-established role in drug resistance, effluxing xenobiotics from cells and tissues within the organism. More recently, research has been dedicated to understanding the role insect ABC transporters play in insecticide toxicity, but progress in understanding the contribution of specific transporters has been hampered by the lack of functional genetic tools. Here, we report knockouts of three Drosophila melanogaster ABC transporter genes, Mdr49, Mdr50, and Mdr65, that are homologous to the well-studied mammalian ABCB1 (P-glycoprotein). Each knockout mutant was created in the same wild type background and tested against a panel of insecticides representing different chemical classes. Mdr65 knockouts were more susceptible to all neuroactive insecticides tested, but Mdr49 and Mdr50 knockouts showed increased susceptibility or resistance depending on the insecticide used. Mdr65 was chosen for further analysis. Calculation of LC50 values for the Mdr65 knockout allowed the substrate specificity of this transporter to be examined. No obvious distinguishing structural features were shared among MDR65 substrates. A role for Mdr65 in insecticide transport was confirmed by testing the capacity of the knockout to synergize with the ABC inhibitor verapamil and by measuring the levels of insecticide retained in the body of knockout flies. These data unambiguously establish the influence of ABC transporters on the capacity of wild type D. melanogaster to tolerate insecticide exposure and suggest that both tissue and substrate specificity underpin this capacity.
      Graphical abstract image

      PubDate: 2017-10-26T05:16:53Z
      DOI: 10.1016/j.ibmb.2017.09.017
       
  • Biochemical identification of residues that discriminate between
           3,4-dihydroxyphenylalanine decarboxylase and
           3,4-dihydroxyphenylacetaldehyde synthase-mediated reactions
    • Authors: Jing Liang; Haizhen Ding; Qian Han; Jianyong Li
      Abstract: Publication date: Available online 14 October 2017
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Jing Liang, Haizhen Ding, Qian Han, Jianyong Li
      In available insect genomes, there are several L-3,4-dihydroxyphenylalanine (L-dopa) decarboxylase (DDC)-like or aromatic amino acid decarboxylase (AAAD) sequences. This contrasts to those of mammals whose genomes contain only one DDC. Our previous experiments established that two DDC-like proteins from Drosophila actually mediate a complicated decarboxylation-oxidative deamination process of dopa in the presence of oxygen, leading to the formation of 3,4-dihydroxyphenylacetaldehyde (DHPA), CO2, NH3, and H2O2. This contrasts to the typical DDC-catalyzed reaction, which produces CO2 and dopamine. These DDC-like proteins were arbitrarily named DHPA synthases based on their critical role in insect soft cuticle formation. Establishment of reactions catalyzed by these AAAD-like proteins solved a puzzle that perplexed researchers for years, but to tell a true DHPA synthase from a DDC in the insect AAAD family remains problematic due to high sequence similarity. In this study, we performed extensive structural and biochemical comparisons between DHPA synthase and DDC. These comparisons identified several target residues potentially dictating DDC-catalyzed and DHPA synthase-catalyzed reactions, respectively. Comparison of DHPA synthase homology models with crystal structures of typical DDC proteins, particularly residues in the active sites, provided further insights for the roles these identified target residues play. Subsequent site-directed mutagenesis of the tentative target residues and activity evaluations of their corresponding mutants determined that active site His192 and Asn192 are essential signature residues for DDC- and DHPA synthase-catalyzed reactions, respectively. Oxygen is required in DHPA synthase-mediated process and this oxidizing agent is reduced to H2O2 in the process. Biochemical assessment established that H2O2, formed in DHPA synthase-mediated process, can be reused as oxidizing agent and this active oxygen species is reduced to H2O; thereby avoiding oxidative stress by H2O2. Results of our structural and functional analyses provide a reasonable explanation of mechanisms involved in DHPA synthase-mediated reactions. Based on the key active site residue Asn192, identified in Drosophila DHPA synthase, we were able to distinguish all available insect DHPA synthases from DDC sequences primarily.
      Graphical abstract image

      PubDate: 2017-10-14T08:17:32Z
      DOI: 10.1016/j.ibmb.2017.10.001
       
  • Spider acetylcholine binding proteins: An alternative model to study the
           interaction between insect nAChRs and neonicotinoids
    • Authors: Haibo Bao; Xiangkun Meng; Zewen Liu
      Abstract: Publication date: Available online 6 October 2017
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Haibo Bao, Xiangkun Meng, Zewen Liu
      Acetylcholine binding proteins (AChBPs) are homologs of extracellular domains of nicotinic acetylcholine receptors (nAChRs) and serve as models for studies on nAChRs. Particularly, studies on invertebrate nAChRs that are limited due to difficulties in their heterologous expression have benefitted from the discovery of AChBPs. Thus far, AChBPs have been characterized only in aquatic mollusks, which have shown low sensitivity to neonicotinoids, the insecticides targeting insect nAChRs. However, AChBPs were also found in spiders based on the sequence and tissue expression analysis. Here, we report five AChBP subunits in Pardosa pseudoannulata, a predator enemy against rice insect pests. Spider AChBP subunits shared higher sequence similarities with nAChR subunits of both insects and mammals compared with mollusk AChBP subunits. The AChBP1 subunit of P. pseudoannulata (Pp-AChBP) was then expressed in Sf9 cells. The Ls-AChBP from Lymnaea stagnalis was also expressed for comparison. In both AChBPs, one ligand site per subunit was present at each interface between two adjacent subunits. Neonicotinoids had higher affinities (7.9–18.4 times based on K d or K i values) for Pp-AChBP than for Ls-AChBP, although epibatidine and α-bungarotoxin showed higher affinities for Ls-AChBP. These results indicate that spider AChBP could be used as an alternative model to study the interaction between insect nAChRs and neonicotinoids.
      Graphical abstract image

      PubDate: 2017-10-11T07:48:04Z
      DOI: 10.1016/j.ibmb.2017.09.014
       
  • Expressional divergences of two desaturase genes determine the opposite
           ratios of two sex pheromone components in Helicoverpa armigera and
           Helicoverpa assulta
    • Authors: Rui-Ting Li; Chao Ning; Ling-Qiao Huang; Jun-Feng Dong; Xianchun Li; Chen-Zhu Wang
      Abstract: Publication date: Available online 3 October 2017
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Rui-Ting Li, Chao Ning, Ling-Qiao Huang, Jun-Feng Dong, Xianchun Li, Chen-Zhu Wang
      The sympatric closely related species Helicoverpa armigera and Helicoverpa assulta use 97:3 and 7:93 of (Z)-11-hexadecenal and (Z)-9-hexadecenal, respectively, as their sex pheromone to find/locate correct sex mates. Moreover, (Z)-11-hexadecenyl alcohol and (Z)-9-hexadecenyl alcohol are more abundant in the pheromone gland of H. assulta than in that of H. armigera. To clarify the molecular basis of these differences, we sequenced the pheromone gland transcriptomes of the two species and compared the expression patterns of the candidate enzyme genes involved in the pheromone biosynthetic pathways by FPKM values and quantitative RT-PCR analysis. We found that the desaturase gene LPAQ expressed about 70 times higher in H. armigera than in H. assulta, whereas another desaturase gene NPVE expressed about 60 times higher in H. assulta than in H. armigera. We also observed significantly higher expression of the fatty acyl reductase (FAR) gene FAR1 and the aldehyde reductase (AR) gene AR3 in H. assulta than in H. armigera. Examination of the pheromone glands of the backcross offspring of their hybrids to H. assulta showed a positive linear correlation between the expression level of LPAQ and the amount of Z11-16:Ald and between the expression level of NPVE and the amount of Z9-16:Ald in the pheromone glands. Taken together, these data demonstrate that the expressional divergence of LPAQ and NPVE determine the opposite sex pheromone component ratios in the two species and the divergent expression of FAR1 and AR3 may account for the greater accumulation of alcohols in the pheromone gland of H. assulta.
      Graphical abstract image

      PubDate: 2017-10-04T09:30:33Z
      DOI: 10.1016/j.ibmb.2017.09.016
       
  • Functions and substrates of NEDDylation during cell cycle in the silkworm,
           Bombyx mori
    • Authors: Zhiqing Li; Qixin Cui; Xiaoyan Wang; Bingqian Li; Dongchao Zhao; Qingyou Xia; Ping Zhao
      Abstract: Publication date: Available online 28 September 2017
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Zhiqing Li, Qixin Cui, Xiaoyan Wang, Bingqian Li, Dongchao Zhao, Qingyou Xia, Ping Zhao
      NEDDylation, a post-translational modification mediated by the conjugation of the ubiquitin-like protein Nedd8 to specific substrates, is an essential biological process that regulates cell cycle progression in eukaryotes. Here, we report the conservation of NEDDylation machinery and NEDDylated proteins in the silkworm, Bombyx mori. We have identified all the components necessary for reversible NEDDylation in the silkworm including Nedd8, E1, E2, E3, and deNEDDylation enzymes. By the approach of RNAi-mediated gene silencing, it was shown that knockdown of BmNedd8 and the conjugating enzymes decreased the global level of NEDDylation, while knockdown of deNEDDylation enzymes increased the prevalence of this modification in cultured silkworm cells. Moreover, the lack of the NEDDylation system caused cell cycle arrest at the G2/M phase and resulted in defects in chromosome congression and segregation. Using the wild-type and mutants of BmNedd8, we identified the specific substrates of BmNedd8, which are involved in the regulation for many cellular processes, including ribosome biogenesis, spliceosome structure, spindle formation, metabolism, and RNA biogenesis. This clearly demonstrates that the NEDDylation system is able to control multiple pathways in the silkworm. Altogether, the information on the functions and substrates of the NEDDylation system presented here could provide a basis for future investigations of protein NEDDylation and its regulatory mechanism on cell cycle progression in the silkworm.
      Graphical abstract image

      PubDate: 2017-10-04T09:30:33Z
      DOI: 10.1016/j.ibmb.2017.09.013
       
  • Accumulation of dsRNA in endosomes contributes to inefficient RNA
           interference in the fall armyworm, Spodoptera frugiperda
    • Authors: June-Sun Yoon; Dhandapani Gurusamy; Subba Reddy Palli
      Abstract: Publication date: Available online 23 September 2017
      Source:Insect Biochemistry and Molecular Biology
      Author(s): June-Sun Yoon, Dhandapani Gurusamy, Subba Reddy Palli
      RNA interference (RNAi) efficiency varies among insects studied. The barriers for successful RNAi include the presence of double-stranded ribonucleases (dsRNase) in the lumen and hemolymph that could potentially digest double-stranded RNA (dsRNA) and the variability in the transport of dsRNA into and within the cells. We recently showed that the dsRNAs are transported into lepidopteran cells, but they are not processed into small interference RNAs (siRNAs) because they are trapped in acidic bodies. In the current study, we focused on the identification of acidic bodies in which dsRNAs accumulate in Sf9 cells. Time-lapse imaging studies showed that dsRNAs enter Sf9 cells and accumulate in acidic bodies within 20 min after their addition to the medium. CypHer-5E-labeled dsRNA also accumulated in the midgut and fat body dissected from Spodoptera frugiperda larvae with similar patterns observed in Sf9 cells. Pharmacological inhibitor assays showed that the dsRNAs use clathrin receptor-mediated endocytosis pathway for transport into the cells. We investigated the potential dsRNA accumulation sites employing LysoTracker and double labeling experiments using the constructs to express a fusion of green fluorescence protein with early or late endosomal marker proteins and CypHer-5E-labeled dsRNA. Interestingly, CypHer-5E-labeled dsRNA accumulated predominantly in early and late endosomes. These data suggest that entrapment of internalized dsRNA in endosomes is one of the major factors contributing to inefficient RNAi response in lepidopteran insects.
      Graphical abstract image

      PubDate: 2017-09-27T08:57:22Z
      DOI: 10.1016/j.ibmb.2017.09.011
       
  • Cap n collar transcription factor regulates multiple genes coding for
           proteins involved in insecticide detoxification in the red flour beetle,
           Tribolium castaneum
    • Authors: Megha Kalsi; Subba Reddy Palli
      Abstract: Publication date: Available online 23 September 2017
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Megha Kalsi, Subba Reddy Palli
      In invertebrates, a heterodimer of xenobiotic transcription factors, cap n collar C isoform (CncC) and muscle aponeurosis fibromatosis (Maf) mediate cellular defense. In insects, these proteins regulate expression of genes involved in insecticide detoxification. In the current study, we performed sequencing of cDNA copied from RNA isolated from Tribolium castaneum pyrethroid resistant strain (QTC279) beetles injected with CncC or green fluorescence protein (GFP, control) dsRNA. Differential expression analysis of sequences identified 662 genes that showed a decrease and 91 genes that showed an increase in expression (p value ≤ 0.01 and log2 fold change of ≥ 1.5) in CncC knockdown insects when compared to their expression in control insects. We selected a subset of 27 downregulated genes and verified their differential expression using qRT-PCR. This subset of 27 genes included 21 genes with a predicted function in xenobiotic detoxification. RNAi and insecticide bioassays were employed to study the function of six of these genes coding for CYP4G7, CYP4G14, GST-1 and four ABC transporters, ABCA-UB, ABCA-A1 and ABCA-A1L and ABCA-9B involved in all three phases of insecticide detoxification. These data suggest that CncC regulates genes coding for proteins involved in detoxification of insecticides.
      Graphical abstract image

      PubDate: 2017-09-27T08:57:22Z
      DOI: 10.1016/j.ibmb.2017.09.009
       
  • Leptinotarsa hormone receptor 4 (HR4) tunes ecdysteroidogenesis and
           mediates 20-hydroxyecdysone signaling during larval-pupal metamorphosis
    • Authors: Qing-Yu Xu; Qing-Wei Meng; Pan Deng; Wen-Chao Guo; Guo-Qing Li
      Abstract: Publication date: Available online 22 September 2017
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Qing-Yu Xu, Qing-Wei Meng, Pan Deng, Wen-Chao Guo, Guo-Qing Li
      Hormone receptor 4 (HR4) is involved in the regulation of 20-hydroxyecdysone (20E) biosynthesis and the mediation of 20E signaling during larval-pupal transition in a holometabolan Drosophila melanogaster, whereas it acts as a repressor in 20E-responsive transcriptional cascade in a hemimetabolan, Blattella germanica. Here we characterized two HR4 splicing variants, LdHR4X1 and LdHR4X2, in a coleopteran Leptinotarsa decemlineata. LdHR4X1 was highly expressed in the prothoracic gland and epidermis while LdHR4X2 was abundantly transcribed in the nervous system. In vivo results showed that both prothoracicotropic hormone and 20E pathways transcriptionally regulated LdHR4, in an isoform-dependent pattern. RNA interference of LdHR4 at the final (fourth) larval instar, in contrast to the second- and third-instar periods, enhanced the expression of two ecdysteroidogenesis genes, increased 20E titer, upregulated transcription of five 20E-response genes, and reduced the mRNA level of Fushi tarazu-factor 1 (FTZ-F1). As a result, the fourth-instar LdHR4 RNAi larvae exhibited accelerated development and reduced body weight. Moreover, knockdown of LdHR4 at the fourth instar resulted in larval lethality and impaired pupation. Feeding of pyriproxyfen (a mimic of juvenile hormone) or silencing of a juvenile hormone degrading enzyme gene restored the normal course of ecdysteroidogenesis, duration of larval development, and body weight in fourth-instar LdHR4 RNAi larvae. The treatment partially suppressed the larval mortality but not the failure to pupate. The dual role of HR4 during larval-pupal metamorphosis appears to be evolutionarily conserved among holometabolans.
      Graphical abstract image

      PubDate: 2017-09-27T08:57:22Z
      DOI: 10.1016/j.ibmb.2017.09.012
       
  • A new Drosophila octopamine receptor responds to serotonin
    • Authors: Yi-xiang Qi; Gang Xu; Gui-xiang Gu; Fen Mao; Gong-yin Ye; Weiwei Liu; Jia Huang
      Abstract: Publication date: Available online 21 September 2017
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Yi-xiang Qi, Gang Xu, Gui-xiang Gu, Fen Mao, Gong-yin Ye, Weiwei Liu, Jia Huang
      As the counterparts of the vertebrate adrenergic transmitters, octopamine and tyramine are important physiological regulators in invertebrates. They control and modulate many physiological and behavioral functions in insects. In this study, we reported the pharmacological properties of a new α2-adrenergic-like octopamine receptor (CG18208) from Drosophila melanogaster, named DmOctα2R. This new receptor gene encodes two transcripts by alternative splicing. The long isoform DmOctα2R-L differs from the short isoform DmOctα2R-S by the presence of an additional 29 amino acids within the third intracellular loop. When heterologously expressed in mammalian cell lines, both receptors were activated by octopamine, tyramine, epinephrine and norepinephrine, resulting in the inhibition of cAMP production in a dose-dependent manner. The long form is more sensitive to the above ligands than the short form. The adrenergic agonists naphazoline, tolazoline and clonidine can stimulate DmOctα2R as full agonists. Surprisingly, serotonin and serotoninergic agonists can also activate DmOctα2R. Several tested adrenergic antagonists and serotonin antagonists blocked the action of octopamine or serotonin on DmOctα2R. The data presented here reported an adrenergic-like G protein-coupled receptor activated by serotonin, suggesting that the neurotransmission and neuromodulation in the nervous system could be more complex than previously thought.
      Graphical abstract image

      PubDate: 2017-09-27T08:57:22Z
      DOI: 10.1016/j.ibmb.2017.09.010
       
  • The microRNA ame-miR-279a regulates sucrose responsiveness of forager
           honey bees (Apis mellifera)
    • Authors: Fang Liu; Tengfei Shi; Wei Yin; Xin Su; Lei Qi; Zachary Y. Huang; Shaowu Zhang; Linsheng Yu
      Abstract: Publication date: Available online 20 September 2017
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Fang Liu, Tengfei Shi, Wei Yin, Xin Su, Lei Qi, Zachary Y. Huang, Shaowu Zhang, Linsheng Yu
      Increasing evidence demonstrates that microRNAs (miRNA) play an important role in the regulation of animal behaviours. Honey bees (Apis mellifera) are eusocial insects, with honey bee workers displaying age-dependent behavioural maturation. Many different miRNAs have been implicated in the change of behaviours in honey bees and ame-miR-279a was previously shown to be more highly expressed in nurse bee heads than in those of foragers. However, it was not clear whether this difference in expression was associated with age or task performance. Here we show that ame-miR-279a shows significantly higher expression in the brains of nurse bees relative to forager bees regardless of their ages, and that ame-miR-279a is primarily localized in the Kenyon cells of the mushroom body in both foragers and nurses. Overexpression of ame-miR-279a attenuates the sucrose responsiveness of foragers, while its absence enhances their sucrose responsiveness. Lastly, we determined that ame-miR-279a directly target the mRNA of Mblk-1. These findings suggest that ame-miR-279a plays important roles in regulating honey bee division of labour.
      Graphical abstract image

      PubDate: 2017-09-27T08:57:22Z
      DOI: 10.1016/j.ibmb.2017.09.008
       
  • Maternal provision of transformer-2 is required for female development and
           embryo viability in the wasp Nasonia vitripennis
    • Authors: Elzemiek Geuverink; Anna H. Rensink; Inge Rondeel; Leo W. Beukeboom; Louis van de Zande; Eveline C. Verhulst
      Abstract: Publication date: Available online 18 September 2017
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Elzemiek Geuverink, Anna H. Rensink, Inge Rondeel, Leo W. Beukeboom, Louis van de Zande, Eveline C. Verhulst
      In insect sex determination a primary signal starts the genetic sex determination cascade that, in most insect orders, is subsequently transduced down the cascade by a transformer (tra) ortholog. Only a female-specifically spliced tra mRNA yields a functional TRA-protein that forms a complex with TRA2, encoded by a transformer-2 (tra2) ortholog, to act as a sex specific splicing regulator of the downstream transcription factors doublesex (dsx) and fruitless (fru). Here, we identify the tra2 ortholog of the haplodiploid parasitoid wasp N. vitripennis (Nv-tra2) and confirm its function in N. vitripennis sex determination. Knock down of Nv-tra2 by parental RNA interference (pRNAi) results in complete sex reversal of diploid offspring from female to male, indicating the requirement of Nv-tra2 for female sex determination. As Nv-tra2 pRNAi leads to frequent lethality in early developmental stages, maternal provision of Nv-tra2 transcripts is apparently also required for another, non-sex determining function during embryogenesis. In addition, lethality following Nv-tra2 pRNAi appears more pronounced in diploid than in haploid offspring. This diploid lethal effect was also observed following Nv-tra pRNAi, which served as a positive control in our experiments. As diploid embryos from fertilized eggs have a paternal chromosome set in addition to the maternal one, this suggests that either the presence of this paternal chromosome set or the dosage effect resulting from the diploid state is incompatible with the induced male development in N. vitripennis caused by either Nv-tra2 or Nv-tra pRNAi. The role of Nv-tra2 in activating the female sex determination pathway yields more insight into the sex determination mechanism of Nasonia.
      Graphical abstract image

      PubDate: 2017-09-20T02:58:32Z
      DOI: 10.1016/j.ibmb.2017.09.007
       
  • Adipokinetic hormone receptor gene identification and its role in
           triacylglycerol mobilization and sexual behavior in the oriental fruit fly
           (Bactrocera dorsalis)
    • Authors: Qiu-Li Hou; Er-Hu Chen; Hong-Bo Jiang; Dan-Dan Wei; Shun-Hua Gui; Jin-Jun Wang; Guy Smagghe
      Abstract: Publication date: Available online 15 September 2017
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Qiu-Li Hou, Er-Hu Chen, Hong-Bo Jiang, Dan-Dan Wei, Shun-Hua Gui, Jin-Jun Wang, Guy Smagghe
      Energy homeostasis requires continuous compensation for fluctuations in energy expenditure and availability of food resources. In insects, energy mobilization is under control of the adipokinetic hormone (AKH) where it is regulating the nutritional status by supporting the mobilization of lipids. In this study, we characterized the gene coding for the AKH receptor (AKHR) and investigated its function in the oriental fruit fly (Bactrocera dorsalis) that is economically one of the most important pest insects of tropical and subtropical fruit. Bacdo-AKHR is a typical G protein-coupled receptor (GPCR) and phylogenetic analysis confirmed that Bacdo-AKHR is closely related to insect AKHRs from other species. When expressed in Chinese hamster ovary (CHO) cells, Bacdo-AKHR exhibited a high sensitivity and selectivity for AKH peptide (EC50 = 19.3 nM). Using qPCR, the developmental stage and tissue-specific expression profiles demonstrated that Bacdo-AKHR was highly expressed in both the larval and adult stages, and also specifically in the fat body and midgut of the adult with no difference in sex. To investigate the role of AKHR in B. dorsalis, RNAi assays were performed with dsRNA against Bacdo-AKHR in adult flies of both sexes and under starvation and feeding condition. As major results, the knockdown of this gene resulted in triacylglycerol (TAG) accumulation. With RNAi-males, we observed a severe decrease in their sexual courtship activity when starved, but there was a partial rescue in copulation when refed. Also in RNAi-males, the tethered-flight duration declined compared with the control group when starved, which is confirming the dependency on energy metabolism. In RNAi-females, the sexual behavior was not affected, but their fecundity was decreased. Our findings indicate an interesting role of AKHR in the sexual behavior of males specifically. The effects are associated with TAG accumulation, and we also reported that the conserved role of AKH-mediated system in B. dorsalis is nutritional state-dependent. Hence, we provided further understanding on the multiple functions of AKH/AKHR in B. dorsalis.
      Graphical abstract image

      PubDate: 2017-09-20T02:58:32Z
      DOI: 10.1016/j.ibmb.2017.09.006
       
  • Recombinant expression and characterization of Lucilia cuprina CYP6G3:
           Activity and binding properties toward multiple pesticides
    • Authors: Matthew J. Traylor; Jong-Min Baek; Katelyn E. Richards; Roberto Fusetto; W. Huang; Peter Josh; Zhengzhong Chen; Padma Bollapragada; Richard A.J. O'Hair; Philip Batterham; Elizabeth M.J. Gillam
      Abstract: Publication date: Available online 14 September 2017
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Matthew J. Traylor, Jong-Min Baek, Katelyn E. Richards, Roberto Fusetto, W. Huang, Peter Josh, Zhengzhong Chen, Padma Bollapragada, Richard A.J. O'Hair, Philip Batterham, Elizabeth M.J. Gillam
      The Australian sheep blowfly, Lucilia cuprina, is a primary cause of sheep flystrike and a major agricultural pest. Cytochrome P450 enzymes have been implicated in the resistance of L. cuprina to several classes of insecticides. In particular, CYP6G3 is a L. cuprina homologue of Drosophila melanogaster CYP6G1, a P450 known to confer multi-pesticide resistance. To investigate the basis of resistance, a bicistronic Escherichia coli expression system was developed to co-express active L. cuprina CYP6G3 and house fly (Musca domestica) P450 reductase. Recombinant CYP6G3 showed activity towards the high-throughput screening substrates, 7-ethoxycoumarin and p-nitroanisole, but not towards p-nitrophenol, coumarin, 7-benzyloxyresorufin, or seven different luciferin derivatives (P450-Glo™ substrates). The addition of house fly cytochrome b 5 enhanced the kcat for p-nitroanisole dealkylation approximately two fold (17.8 ± 0.5 vs 9.6 ± 0.2 min−1) with little effect on KM (13 ± 1 vs 10 ± 1 μM). Inhibition studies and difference spectroscopy revealed that the organochlorine compounds, DDT and endosulfan, and the organophosphate pesticides, malathion and chlorfenvinphos, bind to the active site of CYP6G3. All four pesticides showed type I binding spectra with spectral dissociation constants in the micromolar range suggesting that they may be substrates of CYP6G3. While no significant inhibition was seen with the organophosphate, diazinon, or the neonicotinoid, imidacloprid, diazinon showed weak binding in spectral assays, with a Kd value of 23 ± 3 μM CYP6G3 metabolised diazinon to the diazoxon and hydroxydiazinon metabolites and imidacloprid to the 5-hydroxy and olefin metabolites, consistent with a proposed role of CYP6G enzymes in metabolism of phosphorothioate and neonicotinoid insecticides in other species.
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      PubDate: 2017-09-14T11:48:29Z
      DOI: 10.1016/j.ibmb.2017.09.004
       
  • Identification of circular RNA in the Bombyx mori silk gland
    • Authors: Huaiyan Gan; Tieshan Feng; Yuqian Wu; Chun Liu; Qingyou Xia; Tingcai Cheng
      Abstract: Publication date: Available online 14 September 2017
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Huaiyan Gan, Tieshan Feng, Yuqian Wu, Chun Liu, Qingyou Xia, Tingcai Cheng
      Bombyx mori is an economically important holometabolous lepidopteran insect. In B. mori endogenous noncoding RNAs such as microRNAs (miRNAs) and Piwi-interacting RNAs play crucial biological functions in metamorphosis and sex determination. In addition, circular RNAs (circRNAs) have been recently identified as noncoding RNAs in most common model organisms and show potential as gene regulators. However, to date, there have been few studies on the circRNAs present in the B. mori genome conducted to date. Here, we identified 3916 circRNAs by deep circular transcriptome sequencing using the silk gland of B. mori. 3155 circRNAs were found to be derived from 1727 parental genes. The circRNAs displayed tissue-specific expression between the middle silk gland (MSG) and posterior silk gland (PSG), with 2532 and 880 being upregulated circRNAs in the MSG and PSG, respectively. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway analyses showed that the parental genes from the MSG and PSG were generally annotated to similar categories and pathways. The interaction network of circRNAs and miRNAs showed that circRNAs might act as miRNA sponges or interact with miRNAs in some other way. Overall, the results revealed the complicated patterns of circRNAs in the B. mori silk gland providing a new angle from which to explore the mechanisms of complex gene regulation and efficient silk protein synthesis.
      Graphical abstract image

      PubDate: 2017-09-14T11:48:29Z
      DOI: 10.1016/j.ibmb.2017.09.003
       
  • CRISPR/Cas9 mediated G4946E substitution in the ryanodine receptor of
           Spodoptera exigua confers high levels of resistance to diamide
           insecticides
    • Authors: Yayun Zuo; Hui Wang; Yanjun Xu; Jianlei Huang; Shuwen Wu; Yidong Wu; Yihua Yang
      Abstract: Publication date: Available online 12 September 2017
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Yayun Zuo, Hui Wang, Yanjun Xu, Jianlei Huang, Shuwen Wu, Yidong Wu, Yihua Yang
      Diamide insecticides selectively activate insect ryanodine receptors (RyRs), inducing uncontrolled release of calcium ions, and causing muscle contraction, paralysis and eventually death. The RyRG4946E substitution associated with diamide resistance has been identified in three lepidopteran pests, Plutella xylostella, Tuta absoluta and Chilo suppressalis. Recently, the T. absoluta RyRG4946V mutation was knocked into the model insect Drosophila melanogaster by CRISPR/Cas9 mediated genome editing and provided in vivo functional confirmation for its role in diamide resistance. In the present study, we successfully introduced the RyRG4946E mutation with CRISPR/Cas9 technology into a lepidopteran pest of global importance, Spodoptera exigua. The genome-edited strain (named 4946E) homozygous for the SeRyRG4946E mutation exhibited 223-, 336- and >1000-fold resistance to chlorantraniliprole, cyantraniliprole and flubendiamide, respectively when compared to the wild type strain (WHS) of S. exigua. Reciprocal crossing experiments revealed that the target-site resistance in strain 4946E underlies an autosomal and almost recessive mode of inheritance for anthranilic diamides, whereas it was completely recessive for flubendiamide. Our results not only provided in vivo functional validation of the RyRG4946E mutation in conferring high levels of resistance to diamide insecticides for the first time in a controlled genetic background of a lepidopteran pest, but also revealed slight differences on the level of resistance between anthranilic diamides (chlorantraniliprole and cyantraniliprole) and flubendiamide conferred by the SeRyRG4946E mutation.
      Graphical abstract image

      PubDate: 2017-09-14T11:48:29Z
      DOI: 10.1016/j.ibmb.2017.09.005
       
  • Molecular basis of peripheral olfactory sensing during oviposition in the
           behavior of the parasitic wasp Anastatus japonicus
    • Authors: Yinliang Wang; Qi Chen; Junqi Guo; Jing Li; Jiatong Wang; Ming Wen; Hanbo Zhao; Bingzhong Ren
      Abstract: Publication date: Available online 11 September 2017
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Yinliang Wang, Qi Chen, Junqi Guo, Jing Li, Jiatong Wang, Ming Wen, Hanbo Zhao, Bingzhong Ren
      Anastatus japonicus is a parasitic wasp and natural enemy of the litchi pest Tessaratoma papillosa, and for decades in China, A. japonicus has been mass-reared inside the eggs of Antheraea pernyi to control T. papillosa. A series of experiments was performed to explore the olfactory mechanism underlying the oviposition behavior of A. japonicus. First, a transcriptomic analysis was performed on the antennae of A. japonicus, and the resulting assemblies led to the generation of 70,473 unigenes. Subsequently, 21,368 unigenes were matched to known proteins, and 48 odorant receptors (ORs) (including Orco) and 13 antennal ionotropic receptors (IRs) (including the co-receptors IR8a and IR25a) were identified and predicted to form complete open reading frames (ORFs). The FPKM (fragments per Kb per million reads) values and RT-PCR results showed that AjapOrco, AjapOR10, AjapOR11, AjapOR27, AjapOR29, AjapOR33, AjapOR34 and AjapOR35 were either highly abundant or expressed specifically in the olfactory organs. Furthermore, AjapOrco silencing resulted in a significant decrease in both the parasitism rate and the host-seeking time of A. japonicus, whereas dsRNA injection showed that IR8a and IR25a did not produce significant behavioral changes, suggesting that the oviposition behavior of A. japonicus is more reliant on OR-based pathways than IR-based pathways. Our previous GC-MS data derived twenty-nine compounds from these host plants and host insects. We performed electrophysiological and oviposition assays on A. japonicus, and eight odorants were found to elicit a significant electroantennogram (EAG) response. Among these odorants, β-Caryophyllene, Undecane, (E)-α-Farnesene (+)-Aromadendrene and Cis-3-Hexen-ol had strong attractant effects on oviposition, whereas 2-Ethyl-1-Hexan-ol, Ethyl Acetate and α-Caryophyllene had a strong repellant effects. Thus, these chemicals might influence oviposition guidance/repulsion behavior in A. japonicus. To further explore the target ORs that are tuned to the functional odorants, the nine candidate ORs described above were silenced by RNA interference, and the results showed that a large decrease in the EAG response of all the tested functional odorants in the AjapOrco-silencing group. In addition, the AjapOR35-silencing group showed a significant decrease in the EAG response to β-Caryophyllene and (E)-α-Farnesene, indicating that AjapOR35 is tuned to these two oviposition attractants β-Caryophyllene and (E)-α-Farnesene. Further binary-choice oviposition assays showed that the oviposition attractant effect of β-Caryophyllene and (E)-α-Farnesene vanished after AjapOR35 was silenced, indicating that the emission of these attractants from host plants can guide A. japonicus to locate eggs for ovipositioning and indicated that AjapOR35 is correlated with the olfactory detection oviposition behavior of this species. This study provides a better understanding of the molecular basis and functional chemicals underlying the oviposition behavior of A. japonicus, and the results may help improve biocontrol approaches.
      Graphical abstract image

      PubDate: 2017-09-14T11:48:29Z
      DOI: 10.1016/j.ibmb.2017.09.001
       
  • Functional characterization of Pol III U6 promoters for gene knockdown and
           knockout in Plutella xylostella
    • Authors: Yuping Huang; Yajun Wang; Baosheng Zeng; Zhaoxia Liu; Xuejiao Xu; Qian Meng; Yongping Huang; Guang Yang; Liette Vasseur; Geoff M. Gurr; Minsheng You
      Abstract: Publication date: Available online 7 September 2017
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Yuping Huang, Yajun Wang, Baosheng Zeng, Zhaoxia Liu, Xuejiao Xu, Qian Meng, Yongping Huang, Guang Yang, Liette Vasseur, Geoff M. Gurr, Minsheng You
      RNA polymerase type III (Pol-III) promoters such as U6 are commonly used to express small RNAs, including short hairpin RNAs (shRNAs) and single guide RNAs (sgRNAs). Functional U6 promoters are widely used in CRISPR systems, and their characterization can facilitate genome editing of non-model organisms. In the present study, six U6 small nuclear RNA (snRNA) promoters containing two conserved elements of a proximal sequence element (PSEA) and a TATA box, were identified and characterized in the diamondback moth (Plutella xylostella) genome. Relative efficiency of the U6 promoters to express shRNA induced EGFP knockdown was tested in a P. xylostella cell line, revealing that the PxU6:3 promoter had the strongest expression effect. Further work with the PxU6:3 promoter showed its efficacy in EGFP knockout using CRISPR/Cas9 system in the cells. The expression plasmids with versatile Pxabd-A gene specific sgRNA driven by the PxU6:3 promoter, combined with Cas9 mRNA, could induce mutagenesis at specific genomic loci in vivo. The phenotypes induced by sgRNA expression plasmids were similar to those done in vitro transcription sgRNAs. A plasmid with two tandem arranged PxU6:3:sgRNA expression cassettes targeting Pxabd-A loci was generated, which caused a 28,856 bp fragment deletion, suggesting that the multi-sgRNA expression plasmid can be used for multi-targeting. Our work indicates that U6 snRNA promoters can be used for functional studies of genes with the approach of reverse genetics in P. xylostella. These essential promoters also provide valuable potential for CRISPR-derived gene drive as a tactic for population control in this globally significant pest.
      Graphical abstract image

      PubDate: 2017-09-09T14:15:59Z
      DOI: 10.1016/j.ibmb.2017.08.009
       
  • Osiris9a is a major component of silk fiber in lepidopteran insects
    • Authors: Chun Liu; Wenbo Hu; Tingcai Cheng; Zhangchuan Peng; Kazuei Mita; Qingyou Xia
      Abstract: Publication date: Available online 5 September 2017
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Chun Liu, Wenbo Hu, Tingcai Cheng, Zhangchuan Peng, Kazuei Mita, Qingyou Xia
      In a previous high-throughput proteomics study, it was found that the silkworm cocoon contains hundreds of complex proteins, many of which have unknown functions, in addition to fibroins, sericins, and some protease inhibitors. Osiris was one of the proteins with no known function. In this study, we identified the Osiris gene family members and constructed a phylogenetic tree based on the sequences from different species. Our results indicate that the Osiris9 gene subfamily contains six members; it is specifically expressed in lepidopteran insects and has evolved by gene duplication. An Osiris gene family member from Bombyx mori was designated as BmOsiris9a (BmOsi9a) on the basis of its homology to Drosophila melanogaster Osiris9. The expression pattern of BmOsi9a showed that it was highly expressed only in the middle silk gland of silkworm larvae, similar to Sericin1 (Ser1). BmOsi9a was visualized as two bands in western blot analysis, implying that it probably undergoes post-translational modifications. Immunohistochemistry analysis revealed that BmOsi9a was synthesized and secreted into the lumen of the middle silk gland, and was localized in the sericin layer in the silk fiber. BmOsi9a was found in the silk fibers of not only three Bombycidae species, viz. B. mori, B. mandarina, and B. huttoni, but also in the fibers collected from Saturniidae species, including Antheraea assama, Antheraea mylitta, and Samia cynthia. Although the exact biological function of Osi9a in the silk fibers is unknown, our results are important because they demonstrate that Osi9a is a common structural component of silk fiber and is expressed widely among the silk-producing Bombycidae and Saturniidae insects. Our results should help in understanding the role of Osi9a in silk fibers.
      Graphical abstract image

      PubDate: 2017-09-09T14:15:59Z
      DOI: 10.1016/j.ibmb.2017.09.002
       
  • Lipidation of BmAtg8 is required for autophagic degradation of p62 bodies
           containing ubiquitinated proteins in the silkworm, Bombyx mori
    • Authors: Ming-Ming Ji; Jae Man Lee; Hiroaki Mon; Kazuhiro Iiyama; Tsuneyuki Tatsuke; Daisuke Morokuma; Masato Hino; Mami Yamashita; Kazuma Hirata; Takahiro Kusakabe
      Abstract: Publication date: Available online 1 September 2017
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Ming-Ming Ji, Jae Man Lee, Hiroaki Mon, Kazuhiro Iiyama, Tsuneyuki Tatsuke, Daisuke Morokuma, Masato Hino, Mami Yamashita, Kazuma Hirata, Takahiro Kusakabe
      p62/Sequestosome-1 (p62/SQSTM1, hereafter referred to as p62) is a major adaptor that allows ubiquitinated proteins to be degraded by autophagy, and Atg8 homologs are required for p62-mediated autophagic degradation, but their relationship is still not understood in Lepidopteran insects. Here it is clearly demonstrated that the silkworm homolog of mammalian p62, Bombyx mori p62 (Bmp62), forms p62 bodies depending on its Phox and Bem1p (PB1) and ubiquitin-associated (UBA) domains. These two domains are associated with Bmp62 binding to ubiquitinated proteins to form the p62 bodies, and the UBA domain is essential for the binding, but Bmp62 still self-associates without the PB1 or UBA domain. The p62 bodies in Bombyx cells are enclosed by BmAtg9-containing membranes and degraded via autophagy. It is revealed that the interaction between the Bmp62 AIM motif and BmAtg8 is critical for the autophagic degradation of the p62 bodies. Intriguingly, we further demonstrate that lipidation of BmAtg8 is required for the Bmp62-mediated complete degradation of p62 bodies by autophagy. Our results should be useful in future studies of the autophagic mechanism in Lepidopteran insects.
      Graphical abstract image

      PubDate: 2017-09-03T19:53:40Z
      DOI: 10.1016/j.ibmb.2017.08.006
       
  • Gene expression and molecular characterization of a novel C-type lectin,
           encapsulation promoting lectin (EPL), in the rice armyworm, Mythimna
           separata
    • Authors: Teruhito Ishihara; Yuki Maruyama; Seiichi Furukawa
      Abstract: Publication date: Available online 1 September 2017
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Teruhito Ishihara, Yuki Maruyama, Seiichi Furukawa
      Insect cellular immune reactions differ depending on the target species. Phagocytosis is activated to scavenge microorganisms such as bacteria and fungi. On the other hand, larger invaders such as parasitoid wasps are eliminated by activation of encapsulation. In this study, we hypothesized that novel determinants regulate cellular immunities independent of surface molecular pattern recognition involving pattern recognition receptors (PRRs). Immune-related genes differentially expressed depending on the treated material size were screened in larval hemocytes of the rice armyworm, Mythimna separata. Consequently, we identified a novel C-type lectin gene up-regulated by injection of large beads but not small beads of identical material. Examination of in vitro effect of the recombinant protein on the immune reactions clarified that the protein activated encapsulation reaction, while it suppressed phagocytosis. These results suggest that this novel C-type lectin designated “encapsulation promoting lectin (EPL)” regulates cellular immunity by a novel immune target size-recognition mechanism.
      Graphical abstract image

      PubDate: 2017-09-03T19:53:40Z
      DOI: 10.1016/j.ibmb.2017.08.008
       
  • Substitutions in the cardenolide binding site and interaction of subunits
           affect kinetics besides cardenolide sensitivity of insect Na,K-ATPase
    • Authors: Safaa Dalla; Michael Baum; Susanne Dobler
      Abstract: Publication date: Available online 1 September 2017
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Safaa Dalla, Michael Baum, Susanne Dobler
      Substitutions within the cardenolide target site of several insects' Na,K-ATPase α-subunits may confer resistance against toxic cardenolides. However, to which extent these substitutions alter the Na,K-ATPase's kinetic properties and how they interact with different β-subunits is not clear. The cardenolide-adapted milkweed bug Oncopeltus fasciatus possesses three paralogs of the α-subunit (A, B, and C) that differ in number and identity of resistance-conferring substitutions. We introduced these substitutions into the α-subunit of Drosophila melanogaster and combined them with the β-subunits Nrv2.2 and Nrv3. The substitutions Q111T-N122H-F786N-T797A (A-copy mimic) and Q111T-N122H-F786N (B-copy mimic) mediated high insensitivity to ouabain, yet they drastically lowered ATPase activity. Remarkably, the identity of the β-subunit was decisive and all α-subunits were less active when combined with Nrv3 than when combined with Nrv2.2. Both the substitutions and the co-expressed β-subunit strongly affected the enyzme's affinity for Na+ and K+. Na+ affinity was considerably higher for all enzymes expressed with nrv3 while expression with nrv2.2 increased K+ affinity. Our results provide the first evidence that resistance against cardenolides comes at the cost of significantly altered kinetic properties of the Na,K-ATPase. The β-subunit can strongly modulate these properties but cannot fully compensate for the effect of the substitutions.
      Graphical abstract image

      PubDate: 2017-09-03T19:53:40Z
      DOI: 10.1016/j.ibmb.2017.08.005
       
  • Mdr65 decreases toxicity of multiple insecticides in Drosophila
           melanogaster
    • Authors: Haina Sun; Nicolas Buchon; Jeffrey G. Scott
      Abstract: Publication date: Available online 10 August 2017
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Haina Sun, Nicolas Buchon, Jeffrey G. Scott
      ABC transporters are ubiquitous membrane-bound proteins, present in both prokaryotes and eukaryotes. The major function of eukaryotic ABC transporters is to mediate the efflux of a variety of substrates (including xenobiotics) out of cells. ABC transporters have been widely investigated in humans, particularly for their involvement in multidrug resistance (MDR). Considerably less is known about their roles in transport and/or excretion in insects. ABC transporters are only known to function as exporters in insects. Drosophila melanogaster has 56 ABC transporter genes, including eight which are phylogenetically most similar to the human Mdr genes (ABCB1 clade). We investigated the role of ABC transporters in the ABCB1 clade in modulating the susceptibility to insecticides. We took advantage of the GAL4/UAS system in D. melanogaster to knockdown the expression levels of Mdr65, Mdr50, Mdr49 and ABCB6 using transgenic UAS-RNAi lines and conditional driver lines. The most notable effects were increased sensitivities to nine different insecticides by silencing of Mdr65. Furthermore, a null mutation of Mdr65 decreased the malathion, malaoxon and fipronil LC50 values by a factor of 1.9, 2.1 and 3.9, respectively. Altogether, this data demonstrates the critical role of ABC transporters, particularly Mdr65, in altering the toxicity of specific, structurally diverse, insecticides in D. melanogaster.
      Graphical abstract image

      PubDate: 2017-08-14T15:46:16Z
      DOI: 10.1016/j.ibmb.2017.08.002
       
  • Gustatory receptor 22e is essential for sensing chloroquine and strychnine
           in Drosophila melanogaster
    • Authors: Seeta Poudel; Yunjung Kim; Junseok Kwak; Sangyun Jeong; Youngseok Lee
      Abstract: Publication date: Available online 24 July 2017
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Seeta Poudel, Yunjung Kim, Junseok Kwak, Sangyun Jeong, Youngseok Lee
      Chloroquine, an amino quinolone derivative commonly used as an anti-malarial drug, is known to impart an unpleasant taste. Little research has been done to study chloroquine taste in insects, therefore, we examined both the deterrant properties and mechanisms underlying chloroquine perception in fruit flies. We identified the antifeedant effect of chloroquine by screening 21 gustatory receptor (Grs) mutants through behavioral feeding assays and electrophysiology experiments. We discovered that two molecular sensors, GR22e and GR33a, act as chloroquine receptors, and found that chloroquine-mediated activation of GRNs occurs through S-type sensilla. At the same time, we successfully recapitulated the chloroquine receptor by expressing GR22e in ectopic gustatory receptor neurons. We also found that GR22e forms a part of the strychnine receptor. We suggest that the Drosophila strychnine receptor might have a very complex structure since five different GRs are required for strychnine-induced action potentials.
      Graphical abstract image

      PubDate: 2017-07-26T13:33:28Z
      DOI: 10.1016/j.ibmb.2017.07.007
       
  • Towards an understanding of the molecular basis of effective RNAi against
           a global insect pest, the whitefly Bemisia tabaci
    • Authors: Yuan Luo; Qingguo Chen; Junbo Luan; Seung Ho Chung; Joyce Van Eck; R. Turgeon; Angela E. Douglas
      Abstract: Publication date: Available online 21 July 2017
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Yuan Luo, Qingguo Chen, Junbo Luan, Seung Ho Chung, Joyce Van Eck, R. Turgeon, Angela E. Douglas
      In planta RNAi against essential insect genes offers a promising route to control insect crop pests, but is constrained for many insect groups, notably phloem sap-feeding hemipterans, by poor RNAi efficacy. This study conducted on the phloem-feeding whitefly Bemisia tabaci reared on tomato plants investigated the causes of low RNAi efficacy and routes to ameliorate the problem. Experiments using tomato transgenic lines containing ds-GFP (green fluorescent protein) revealed that full-length dsRNA is phloem-mobile, ingested by the insects, and degraded in the insect. We identified B. tabaci homologs of nuclease genes (dsRNases) in other insects that degrade dsRNA, and demonstrated that degradation of ds-GFP in B. tabaci is suppressed by administration of dsRNA against these genes. dsRNA against the nuclease genes was co-administered with dsRNA against two insect genes, an aquaporin AQP1 and sucrase SUC1, that are predicted to protect B. tabaci against osmotic collapse. When dsRNA constructs for AQP1, SUC1, dsRNase1 and dsRNase2 were stacked, insect mortality was significantly elevated to 50% over 6 days on artificial diets. This effect was accompanied by significant reduction in gene expression of the target genes in surviving diet-fed insects. This study offers proof-of-principle that the efficacy of RNAi against insect pests can be enhanced by using dsRNA to suppress the activity of RNAi-suppressing nuclease genes, especially where multiple genes with related physiological function but different molecular function are targeted.
      Graphical abstract image

      PubDate: 2017-07-26T13:33:28Z
      DOI: 10.1016/j.ibmb.2017.07.005
       
  • Gene expression changes in honey bees induced by sublethal imidacloprid
           exposure during the larval stage
    • Authors: Ming-Cheng Wu; Yu-Wen Chang; Kuang-Hui Lu; En-Cheng Yang
      Abstract: Publication date: Available online 18 July 2017
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Ming-Cheng Wu, Yu-Wen Chang, Kuang-Hui Lu, En-Cheng Yang
      Honey bee larvae exposed to sublethal doses of imidacloprid show behavioural abnormalities as adult insects. Previous studies have demonstrated that this phenomenon originates from abnormal neural development in response to imidacloprid exposure. Here, we further investigated the global gene expression changes in the heads of newly emerged adults and observed that 578 genes showed more than 2-fold changes in gene expression after imidacloprid exposure. This information might aid in understanding the effects of pesticides on the health of pollinators. For example, the genes encoding major royal jelly proteins (MRJPs), a group of multifunctional proteins with significant roles in the sustainable development of bee colonies, were strongly downregulated. These downregulation patterns were further confirmed through analyses using quantitative reverse transcription-polymerase chain reaction on the heads of 6-day-old nurse bees. To our knowledge, this study is the first to demonstrate that sublethal doses of imidacloprid affect mrjp expression and likely weaken bee colonies.
      Graphical abstract image

      PubDate: 2017-07-20T02:25:55Z
      DOI: 10.1016/j.ibmb.2017.06.016
       
 
 
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