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  Subjects -> BIOLOGY (Total: 3106 journals)
    - BIOCHEMISTRY (245 journals)
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BIOCHEMISTRY (245 journals)                  1 2 | Last

Showing 1 - 200 of 245 Journals sorted alphabetically
AAPS PharmSciTech     Hybrid Journal   (Followers: 7)
Acetic Acid Bacteria     Open Access   (Followers: 2)
ACS Central Science     Open Access   (Followers: 9)
ACS Chemical Biology     Full-text available via subscription   (Followers: 289)
ACS Chemical Neuroscience     Full-text available via subscription   (Followers: 21)
Acta Biochimica Polonica     Open Access  
Acta Crystallographica Section D : Biological Crystallography     Hybrid Journal   (Followers: 10)
Acta Crystallographica Section F: Structural Biology Communications     Hybrid Journal   (Followers: 10)
Advances and Applications in Bioinformatics and Chemistry     Open Access   (Followers: 11)
Advances in Biological Chemistry     Open Access   (Followers: 9)
Advances in Carbohydrate Chemistry and Biochemistry     Full-text available via subscription   (Followers: 7)
Advances in Plant Biochemistry and Molecular Biology     Full-text available via subscription   (Followers: 7)
Advances in Protein Chemistry and Structural Biology     Full-text available via subscription   (Followers: 18)
African Journal of Biochemistry Research     Open Access   (Followers: 1)
African Journal of Chemical Education     Open Access   (Followers: 3)
Alkaloids: Chemical and Biological Perspectives     Full-text available via subscription   (Followers: 2)
American Journal of Biochemistry     Open Access   (Followers: 9)
American Journal of Biochemistry and Biotechnology     Open Access   (Followers: 63)
American Journal of Biochemistry and Molecular Biology     Open Access   (Followers: 15)
American Journal of Polymer Science     Open Access   (Followers: 30)
Amino Acids     Hybrid Journal   (Followers: 8)
Analytical and Bioanalytical Chemistry Research     Open Access   (Followers: 1)
Analytical Biochemistry     Hybrid Journal   (Followers: 172)
Angiogenesis     Hybrid Journal   (Followers: 3)
Annals of Clinical Biochemistry     Hybrid Journal   (Followers: 8)
Annual Review of Biochemistry     Full-text available via subscription   (Followers: 54)
Annual Review of Chemical and Biomolecular Engineering     Full-text available via subscription   (Followers: 12)
Applied Biochemistry and Biotechnology     Hybrid Journal   (Followers: 42)
Applied Biochemistry and Microbiology     Hybrid Journal   (Followers: 16)
Applied Organometallic Chemistry     Hybrid Journal   (Followers: 8)
Archives of Biochemistry and Biophysics     Hybrid Journal   (Followers: 20)
Archives of Insect Biochemistry and Physiology     Hybrid Journal  
Archives Of Physiology And Biochemistry     Hybrid Journal  
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: 24)
Biochemical and Molecular Medicine     Full-text available via subscription   (Followers: 5)
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: 24)
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: 345)
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: 15)
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: 10)
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)
Biofarmasi Journal of Natural Product Biochemistry     Open Access  
Biofuels     Hybrid Journal   (Followers: 11)
Biogeochemistry     Hybrid Journal   (Followers: 15)
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: 21)
Biosimilars     Open Access   (Followers: 1)
Biotechnology and Applied Biochemistry     Hybrid Journal   (Followers: 44)
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: 7)
Cell Chemical Biology     Hybrid Journal   (Followers: 1)
Cellular Physiology and Biochemistry     Open Access   (Followers: 3)
ChemBioChem     Hybrid Journal   (Followers: 8)
Chemical and Biological Technologies for Agriculture     Open Access  
Chemical Biology & Drug Design     Hybrid Journal   (Followers: 20)
Chemical Engineering Journal     Hybrid Journal   (Followers: 54)
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: 7)
Chemistry & Biology     Full-text available via subscription   (Followers: 32)
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: 69)
Clinical Chemistry and Laboratory Medicine     Hybrid Journal   (Followers: 62)
Clinical Lipidology     Open Access   (Followers: 1)
Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology     Hybrid Journal   (Followers: 7)
Comparative Biochemistry and Physiology Part B: Biochemistry and Molecular Biology     Hybrid Journal   (Followers: 3)
Comparative Biochemistry and Physiology Part C: Toxicology & Pharmacology     Hybrid Journal   (Followers: 6)
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: 11)
Critical Reviews in Biochemistry and Molecular Biology     Hybrid Journal   (Followers: 5)
Current Biochemical Engineering     Hybrid Journal  
Current Chemical Biology     Hybrid Journal   (Followers: 2)
Current Medicinal Chemistry     Hybrid Journal   (Followers: 15)
Current Opinion in Chemical Biology     Hybrid Journal   (Followers: 31)
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: 58)
FEBS Open Bio     Open Access   (Followers: 3)
Fish Physiology and Biochemistry     Hybrid Journal   (Followers: 3)
Food & Function     Full-text available via subscription   (Followers: 7)
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: 18)
Green Chemistry     Full-text available via subscription   (Followers: 10)
Histochemistry and Cell Biology     Hybrid Journal   (Followers: 7)
Indian Journal of Biochemistry and Biophysics (IJBB)     Open Access   (Followers: 2)
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: 6)
International Journal of Biochemistry and Biophysics     Open Access   (Followers: 1)
International Journal of Biological Chemistry     Open Access   (Followers: 2)
International Journal of Biomedical Nanoscience and Nanotechnology     Hybrid Journal   (Followers: 6)
International Journal of Food Contamination     Open Access  
International Journal of Plant Physiology and Biochemistry     Open Access  
International Journal of Plant Research     Open Access   (Followers: 3)
International Journal of Secondary Metabolite     Open Access   (Followers: 1)
Invertebrate Immunity     Open Access   (Followers: 1)
JBIC Journal of Biological Inorganic Chemistry     Hybrid Journal   (Followers: 4)
Journal of Microbial & Biochemical Technology     Open Access   (Followers: 2)
Journal of Applied Biology & Biotechnology     Open Access   (Followers: 3)
Journal of Bioactive and Compatible Polymers     Hybrid Journal   (Followers: 3)
Journal of Biochemical and Biophysical Methods     Hybrid Journal   (Followers: 4)
Journal of Biochemistry     Hybrid Journal   (Followers: 41)
Journal of Biochemistry and Molecular Biology Research     Open Access  
Journal of Biological Chemistry     Full-text available via subscription   (Followers: 204)
Journal of Biomaterials Science, Polymer Edition     Hybrid Journal   (Followers: 9)
Journal of Carbohydrate Chemistry     Hybrid Journal   (Followers: 6)
Journal of Cellular Biochemistry     Hybrid Journal   (Followers: 4)
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: 5)
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   (Followers: 1)
Journal of Food and Drug Analysis     Open Access  
Journal of Forensic Toxicology and Pharmacology     Hybrid Journal   (Followers: 7)
Journal of Inborn Errors of Metabolism and Screening     Open Access  
Journal of Inorganic Biochemistry     Hybrid Journal   (Followers: 6)
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: 4)
Journal of Molecular Diagnostics     Hybrid Journal   (Followers: 5)
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: 21)
Journal of Photochemistry and Photobiology B: Biology     Hybrid Journal   (Followers: 3)
Journal of Physiobiochemical Metabolism     Hybrid Journal   (Followers: 2)
Journal of Physiology and Biochemistry     Hybrid Journal   (Followers: 3)
Journal of Plant Biochemistry and Biotechnology     Hybrid Journal   (Followers: 4)
Journal of Proteins and Proteomics     Open Access  
Journal of Steroid Biochemistry and Molecular Biology     Hybrid Journal   (Followers: 2)
Journal of Virology & Antiviral Research     Hybrid Journal   (Followers: 6)
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: 37)
Laboratory Techniques in Biochemistry and Molecular Biology     Full-text available via subscription   (Followers: 4)
Marine Chemistry     Hybrid Journal   (Followers: 7)
Methods in Enzymology     Full-text available via subscription   (Followers: 12)
Molecular and Biochemical Parasitology     Hybrid Journal   (Followers: 2)
Molecular and Cellular Biochemistry     Hybrid Journal   (Followers: 4)
Molecular Aspects of Medicine     Hybrid Journal   (Followers: 3)
Molecular Informatics     Hybrid Journal   (Followers: 5)
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: 74)
Nature Communications     Open Access   (Followers: 217)
Neurosignals     Open Access  

        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  [3175 journals]
  • Involvement of Methoprene-tolerant (Met) in the determination of the final
           body size in Leptinotarsa decemlineata (Say) larvae
    • Authors: Qing-Wei Meng; Qing-Yu Xu; Pan Deng; Kai-Yun Fu; Wen-Chao Guo; Guo-Qing Li
      Pages: 1 - 9
      Abstract: Publication date: Available online 19 April 2018
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Qing-Wei Meng, Qing-Yu Xu, Pan Deng, Kai-Yun Fu, Wen-Chao Guo, Guo-Qing Li
      In the tobacco hornworm Manduca sexta, juvenile hormone (JH) is critical for the control of species-specific size. However, whether the basic helix-loop-helix/Per-Arnt-Sim domain receptor methoprene-tolerant (Met) is involved remains unconfirmed. In the present paper, we found that RNA interference (RNAi)-aided knockdown of Met gene (LdMet) lowered the larval and pupal fresh weights and shortened the larval development period in the Colorado potato beetle Leptinotarsa decemlineata. Dietary introduction of JH into the LdMet RNAi larvae rescued neither the decreased weights nor the reduced development phase, even though JH ingestion by control larvae extended developmental time and caused large pupae. Moreover, the transcript levels of five genes involved in prothoracicotropic hormone and cap 'n' collar isoform C/Kelch-like ECH associated protein 1 pathways were upregulated in the LdMet silenced larvae. Ecdysteroidogenesis was thereby activated; 20-hydroxyecdysone (20E) titer was increased; and 20E signaling pathway was elicited in the LdMet RNAi larvae. Therefore, JH, acting through its receptor Met, inhibits PTTH production and release before the attainment of critical weight. Once the critical weight is reached, JH production and release are averted; and the hemolymph JH is removed. The elimination of JH allows the brain to release PTTH. PTTH subsequently stimulates ecdysteroid biosynthesis and release to start larval-pupal transition in L. decemlineata.
      Graphical abstract image

      PubDate: 2018-04-26T03:26:00Z
      DOI: 10.1016/j.ibmb.2018.04.003
      Issue No: Vol. 97 (2018)
       
  • Identification of a transcription factor that functions downstream of
           corazonin in the control of desert locust gregarious body color
    • Authors: Ryohei Sugahara; Seiji Tanaka; Akiya Jouraku; Takahiro Shiotsuki
      Pages: 10 - 18
      Abstract: Publication date: Available online 20 April 2018
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Ryohei Sugahara, Seiji Tanaka, Akiya Jouraku, Takahiro Shiotsuki
      Corazonin (Crz) is a neuropeptide that controls phase-dependent body color polyphenism in locusts. The Crz signaling pathway is responsible for the development of gregarious black patterns in nymphs and determination of the morphometric ratio F/C (F = hind femur length, C = maximum head width) in adults. However, little information is available regarding the mediator and effector proteins regulated by Crz. In this study, we identified a novel transcriptional factor, Loct, which functions downstream of Crz in Schistocerca gregaria and Locusta migratoria. In S. gregaria, we detected a variant of Loct lacking the N-terminal region. Protein–protein interaction assays showed that both the long and short Loct variants formed a complex with themselves. LOCT knockdown in gregarious nymphs reduced the intensity of their black patterning, but did not affect F/C ratios in adults. LOCT was exclusively expressed in the integument of gregarious nymphs, suggesting that Loct is involved in melanin production. In addition, we found that the melanization-associated protein Yellow (YEL) and the albino-related takeout protein (ALTO) are expressed in the integument and function downstream of Crz. However, Crz injection failed to influence LOCT, YEL, and ALTO expression. Therefore, additional factors probably cooperate with Crz to induce these genes. The gene expression profiles of YEL and ALTO in LOCT-knockdown nymphs suggest that Loct does not directly control the transcription of YEL or ALTO. In summary, we present a working model of the Crz pathway, which is active in crowded S. gregaria nymphs.
      Graphical abstract image

      PubDate: 2018-04-26T03:26:00Z
      DOI: 10.1016/j.ibmb.2018.04.004
      Issue No: Vol. 97 (2018)
       
  • Multi-tissue GAL4-mediated gene expression in all Anopheles gambiae life
           stages using an endogenous polyubiquitin promoter
    • Authors: Adriana Adolfi; Emilie Pondeville; Amy Lynd; Catherine Bourgouin; Gareth J. Lycett
      Pages: 1 - 9
      Abstract: Publication date: May 2018
      Source:Insect Biochemistry and Molecular Biology, Volume 96
      Author(s): Adriana Adolfi, Emilie Pondeville, Amy Lynd, Catherine Bourgouin, Gareth J. Lycett
      The ability to manipulate the Anopheles gambiae genome and alter gene expression effectively and reproducibly is a prerequisite for functional genetic analysis and for the development of novel control strategies in this important disease vector. However, in vivo transgenic analysis in mosquitoes is limited by the lack of promoters active ubiquitously. To address this, we used the GAL4/UAS system to investigate the promoter of the An. gambiae Polyubiquitin-c (PUBc) gene and demonstrated its ability to drive expression in mosquito cell culture before incorporation into An. gambiae transgenic driver lines. To generate such lines, piggyBac-mediated insertion was used to identify genomic regions able to sustain widespread expression and to create φC31 docking lines at these permissive sites. Patterns of expression induced by PUBc-GAL4 drivers carrying single intergenic insertions were assessed by crossing with a novel responder UAS-mCD8:mCherry line that was created by φC31-mediated integration. Amongst the drivers created at single, unique chromosomal integration loci, two were isolated that induced differential expression levels in a similar multiple-tissue spatial pattern throughout the mosquito life cycle. This work expands the tools available for An. gambiae functional analysis by providing a novel promoter for investigating phenotypes resulting from widespread multi-tissue expression, as well as identifying and tagging genomic sites that sustain broad transcriptional activity.
      Graphical abstract image

      PubDate: 2018-04-19T02:45:34Z
      DOI: 10.1016/j.ibmb.2018.03.005
      Issue No: Vol. 96 (2018)
       
  • A comparative analysis of corpora allata-corpora cardiaca microRNA
           repertoires revealed significant changes during mosquito metamorphosis
    • Authors: Marcela Nouzova; Kayvan Etebari; Fernando G. Noriega; Sassan Asgari
      Pages: 10 - 18
      Abstract: Publication date: May 2018
      Source:Insect Biochemistry and Molecular Biology, Volume 96
      Author(s): Marcela Nouzova, Kayvan Etebari, Fernando G. Noriega, Sassan Asgari
      The corpora allata (CA) are a pair of endocrine glands with neural connections to the brain and close association with another neuroendocrine organ, the corpora cardiaca (CC). The CA from adult female Aedes aegypti mosquitoes synthesize fluctuating levels of juvenile hormone (JH), which have been linked to the ovarian development and are influenced by nutritional signals. In this study, we investigated the potential involvement of microRNAs (miRNAs), a type of small non-coding RNAs, in the regulation of gene expression in CA-CC complexes during mosquito reproductive development, at stages with distinct JH biosynthesis patterns. We analyzed the miRNA repertoires expressed in the CA-CC of pupae, sugar-fed and blood-fed female Ae. aegypti. In total, 156 mature miRNAs were detected in the CA-CC, with 84 displaying significant differences in expression among the three CA-CC developmental stages. There were more miRNAs that were expressed in pupae, and decreased or were absent after adult emergence, when compared with changes between CA-CC of sugar and blood-fed females. Analysis of the genes identified as potential targets for the CA-CC miRNA repertoires classified them into the broad categories of metabolism, information storage and processing, and cellular processes and signaling; with genes involved in cellular processes and signaling representing the largest portion. Among them, the signal-transduction mechanisms and intracellular trafficking, secretion and vesicular transport contained almost 55% of the genes’ targets. A substantial number of miRNAs were differentially abundant in the libraries of the three developmental stages, and those changes were much more notable when pupae and adult stages were compared. We detected putative binding sites for some of the most abundant miRNAs on genes encoding JH biosynthetic enzymes and CC neuropeptides. These studies should help us to gain a better understanding of the regulation of CA-CC activity mediated by miRNAs during major developmental stages in mosquitoes.
      Graphical abstract image

      PubDate: 2018-04-19T02:45:34Z
      DOI: 10.1016/j.ibmb.2018.03.007
      Issue No: Vol. 96 (2018)
       
  • Characterization of a Drosophila glutathione transferase involved in
           isothiocyanate detoxification
    • Authors: Daniel Gonzalez; Stéphane Fraichard; Paul Grassein; Patrice Delarue; Patrick Senet; Adrien Nicolaï; Evelyne Chavanne; Elodie Mucher; Yves Artur; Jean-François Ferveur; Jean-Marie Heydel; Loïc Briand; Fabrice Neiers
      Pages: 33 - 43
      Abstract: Publication date: April 2018
      Source:Insect Biochemistry and Molecular Biology, Volume 95
      Author(s): Daniel Gonzalez, Stéphane Fraichard, Paul Grassein, Patrice Delarue, Patrick Senet, Adrien Nicolaï, Evelyne Chavanne, Elodie Mucher, Yves Artur, Jean-François Ferveur, Jean-Marie Heydel, Loïc Briand, Fabrice Neiers
      Glutathione transferases (GSTs) are ubiquitous key enzymes that catalyse the conjugation of glutathione to xenobiotic compounds in the detoxification process. GSTs have been proposed to play a dual role in the signal termination of insect chemodetection by modifying odorant and tasting molecules and by protecting the chemosensory system. Among the 40 GSTs identified in Drosophila melanogaster, the Delta and Epsilon groups are insect-specific. GSTs Delta and Epsilon may have evolved to serve in detoxification, and have been associated with insecticide resistance. Here, we report the heterologous expression and purification of the D. melanogaster GST Delta 2 (GSTD2). We investigated the capacity of GSTD2 to bind tasting molecules. Among them, we found that isothiocyanates (ITC), insecticidal compounds naturally present in cruciferous plant and perceived as bitter, are good substrates for GSTD2. The X-ray structure of GSTD2 was solved, showing the absence of the classical Ser catalytic residue, conserved in the Delta and Epsilon GSTs. Using molecular dynamics, the interaction of ITC with the GSTD2 three-dimensional structure is analysed and discussed. These findings allow us to consider a biological role for GSTD2 in chemoperception, considering GSTD2 expression in the chemosensory organs and the potential consequences of insect exposure to ITC.
      Graphical abstract image

      PubDate: 2018-04-19T02:45:34Z
      DOI: 10.1016/j.ibmb.2018.03.004
      Issue No: Vol. 95 (2018)
       
  • Molecular cloning, spatiotemporal and functional expression of GABA
           
    • Authors: Cheng-Wang Sheng; Zhong-Qiang Jia; Yoshihisa Ozoe; Qiu-Tang Huang; Zhao-Jun Han; Chun-Qing Zhao
      Pages: 18 - 27
      Abstract: Publication date: March 2018
      Source:Insect Biochemistry and Molecular Biology, Volume 94
      Author(s): Cheng-Wang Sheng, Zhong-Qiang Jia, Yoshihisa Ozoe, Qiu-Tang Huang, Zhao-Jun Han, Chun-Qing Zhao
      Insect γ-aminobutyric acid (GABA) receptor (GABAR) is one of the major targets of insecticides. In the present study, cDNAs (CsRDL1A and CsRDL2S) encoding the two isoforms of RDL subunits were cloned from the rice stem borer Chilo suppressalis. Transcripts of both genes demonstrated similar expression patterns in different tissues and developmental stages, although CsRDL2S was ∼2-fold more abundant than CsRDL1A throughout all development stages. To investigate the function of channels formed by CsRDL subunits, both genes were expressed in Xenopus laevis oocytes singly or in combination in different ratios. Electrophysiological results using a two-electrode voltage clamp demonstrated that GABA activated currents in oocytes injected with both cRNAs. The EC50 value of GABA in activating currents was smaller in oocytes co-injected with CsRDL1A and CsRDL2S than in oocytes injected singly. The IC50 value of the insecticide fluralaner in inhibiting GABA responses was smaller in oocytes co-injected with different cRNAs than in oocytes injected singly. Co-injection also changed the potency of the insecticide dieldrin in oocytes injected singly. These findings suggested that heteromeric GABARs were formed by the co-injections of CsRDL1A and CsRDL2S in oocytes. Although the presence of Ser at the 2′-position in the second transmembrane segment was responsible for the insensitivity of GABARs to dieldrin, this amino acid did not affect the potencies of the insecticides fipronil and fluralaner. These results lead us to hypothesize that C. suppressalis may adapt to insecticide pressure by regulating the expression levels of CsRDL1A and CsRDL2S and the composition of both subunits in GABARs.
      Graphical abstract image

      PubDate: 2018-02-05T15:52:24Z
      DOI: 10.1016/j.ibmb.2018.01.003
      Issue No: Vol. 94 (2018)
       
  • Resistance to Bacillus thuringiensis linked with a cadherin transmembrane
           mutation affecting cellular trafficking in pink bollworm from China
    • Authors: Ling Wang; Yuemin Ma; Peng Wan; Kaiyu Liu; Yutao Xiao; Jintao Wang; Shengbo Cong; Dong Xu; Kongming Wu; Jeffrey A. Fabrick; Xianchun Li; Bruce E. Tabashnik
      Pages: 28 - 35
      Abstract: Publication date: March 2018
      Source:Insect Biochemistry and Molecular Biology, Volume 94
      Author(s): Ling Wang, Yuemin Ma, Peng Wan, Kaiyu Liu, Yutao Xiao, Jintao Wang, Shengbo Cong, Dong Xu, Kongming Wu, Jeffrey A. Fabrick, Xianchun Li, Bruce E. Tabashnik
      Evolution of pest resistance reduces the efficacy of insecticidal proteins from the gram-positive bacterium Bacillus thuringiensis (Bt) used widely in sprays and transgenic crops. In some previously studied strains of three major lepidopteran pests, resistance to Bt toxin Cry1Ac is associated with mutations disrupting the extracellular or cytoplasmic domains of cadherin proteins that bind Cry1Ac in the midgut of susceptible larvae. Here we report the first case of a cadherin transmembrane mutation associated with insect resistance to Bt. We discovered this mutation in a strain of the devastating global cotton pest, the pink bollworm (Pectinophora gossypiella), derived from a field population in the Yangtze River Valley of China. The mutant allele analyzed here has a 207 base pair deletion and encodes a cadherin protein lacking its transmembrane domain. Relative to a susceptible strain, a strain homozygous for this allele had 220-fold resistance to Cry1Ac and 2.1-fold cross-resistance to Cry2Ab. On transgenic cotton plants producing Cry1Ac, no susceptible larvae survived, but the resistant strain completed its life cycle. Inheritance of resistance to Cry1Ac was autosomal, recessive and tightly linked with the cadherin gene. Transportation of cadherin protein to the cell membrane and susceptibility to Cry1Ac occurred in transfected insect cells expressing the wild type cadherin allele, but not in transfected insect cells expressing the mutant cadherin allele. The results imply that the mutant allele analyzed here confers resistance to Cry1Ac by disrupting cellular trafficking of cadherin.
      Graphical abstract image

      PubDate: 2018-03-18T20:31:17Z
      DOI: 10.1016/j.ibmb.2018.01.004
      Issue No: Vol. 94 (2018)
       
  • The intracellular region of silkworm cadherin-like protein is not
           necessary to mediate the toxicity of Bacillus thuringiensis Cry1Aa and
           Cry1Ab toxins
    • Authors: Haruka Endo; Satomi Adegawa; Shingo Kikuta; Ryoichi Sato
      Pages: 36 - 41
      Abstract: Publication date: March 2018
      Source:Insect Biochemistry and Molecular Biology, Volume 94
      Author(s): Haruka Endo, Satomi Adegawa, Shingo Kikuta, Ryoichi Sato
      The cadherin-like protein in lepidopteran insects, known as a receptor for Bacillus thuringiensis Cry1A toxins, is a single-pass membrane protein that can be divided into extracellular and intracellular regions. The extracellular region is important for toxin binding and oligomerization, whereas the role of the intracellular region during Cry1A intoxication is unclear. In the present study, we generated a deletion mutant of Bombyx mori cadherin-like protein (BtR175) that lacked the intracellular region to investigate its role in mediating Cry1A toxicity. Like wild-type BtR175, the mutant protein conferred susceptibility to Cry1Aa and Cry1Ab toxins in Sf9 cells, suggesting that the intracellular region is not required to mediate intoxication. The deletion mutant maintained another role of cadherin-like proteins; that it, synergistic activity with B. mori ABC transporter C2 (ABCC2) when mediating Cry1Aa and Cry1Ab toxicity. In addition, we evaluated the effects of reagents that have been reported to inhibit Cry1A toxicity (e.g., protein kinase A inhibitors, EDTA, and sucrose) on Cry1A toxicity in BtR175-expressing cells. Our results suggest that Cry1Aa-induced cell death in BtR175-expressing cells was not caused by signal transduction but by osmotic lysis. Overall, our data indicate that BtR175 mediates the toxicity of Cry1Aa and Cry1Ab toxins entirely via its extracellular region. They also indicate that the synergism between cadherin-like protein and ABCC2 occurs outside of cells or in the cell membrane.
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      PubDate: 2018-02-15T16:15:59Z
      DOI: 10.1016/j.ibmb.2018.01.005
      Issue No: Vol. 94 (2018)
       
  • 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
      Pages: 50 - 60
      Abstract: Publication date: March 2018
      Source:Insect Biochemistry and Molecular Biology, Volume 94
      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.
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      PubDate: 2018-03-18T20:31:17Z
      DOI: 10.1016/j.ibmb.2017.09.012
      Issue No: Vol. 94 (2018)
       
  • A receptor-neuron correlate for the detection of attractive plant
           volatiles in Helicoverpa assulta (Lepidoptera: Noctuidae)
    • Authors: Wei-chan Cui; Wang Bing; Meng-bo Guo; Yang Liu; Emmanuelle Jacquin-Joly; Shan-chun Yan; Wang Guirong
      Abstract: Publication date: Available online 23 April 2018
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Wei-chan Cui, Wang Bing, Meng-bo Guo, Yang Liu, Emmanuelle Jacquin-Joly, Shan-chun Yan, Wang Guirong
      Plant volatiles are vital cues in the location of hosts for feeding and oviposition for Lepidoptera moths. The noctuid Helicoverpa assulta is a typical polyphagous moth, regarded as a good model for studying the olfactory reception of plant volatiles. In this study, four full-length genes encoding odorant receptors HassOR24, HassOR40, HassOR41, and HassOR55 expressed in antenna in H. assulta were functionally characterized. The highly expressed HassOR40 was narrowly tuned to a few structurally-related plant volatiles: geranyl acetate, geraniol and nerolidol. By systematically analyzing responses of single neuron in both trichoid sensilla and basiconic sensilla using single sensillum recording, the specific neuron B in one type of short trichoid sensilla was found to be mainly activated by the same chemicals as HassOR40 with high sensitivity, and with no significant difference between male and female neurons. Thus, a clear “receptor-neuron” relationship in H. assulta was demonstrated here, suggesting that HassOR40/HassOrco are expressed in neuron B of short trichoid sensilla. The active tobacco volatile nerolidol, recognized by this receptor-neuron line, elicits significant behavioral attraction of both sexes in H. assulta adults. The results indicate that we identified a receptor-neuron route for the peripheral coding of a behaviorally relevant host volatile in H. assulta.
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      PubDate: 2018-04-26T03:26:00Z
      DOI: 10.1016/j.ibmb.2018.04.006
       
  • Dopamine signalling in locusts and other insects
    • Authors: Heleen Verlinden
      Abstract: Publication date: Available online 20 April 2018
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Heleen Verlinden
      Dopamine is an important catecholamine neurotransmitter in invertebrates and vertebrates. It is biochemically derived from tyrosine via L-DOPA. It is most abundant in the central nervous system, but can also be produced in e.g. epidermal cells. Dopamine has conserved roles in the control of movement, pleasure, motivation, arousal and memory between invertebrate and vertebrate animals. It is crucial for melanisation and sclerotisation, important processes for the formation of the exoskeleton of insects and immune function. In this brief review I will discuss some general aspects of insect dopamine biosynthesis and breakdown, dopamine receptors and their pharmacology. In addition, I will provide a glance on the multitude of biological functions of dopamine in insects. More detail is provided concerning the putative roles of dopamine in phase related phenomena in locusts. Finally, molecular and pharmacological adjustments of insect dopamine signalling are discussed in the light of possible approaches towards insect pest management.
      Graphical abstract image

      PubDate: 2018-04-26T03:26:00Z
      DOI: 10.1016/j.ibmb.2018.04.005
       
  • Identification of a cytokine combination that protects insects from stress
    • Authors: Takashi Matsumura; Fumihiro Nakano; Hitoshi Matsumoto; Outa Uryu; Yoichi Hayakawa
      Abstract: Publication date: Available online 19 April 2018
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Takashi Matsumura, Fumihiro Nakano, Hitoshi Matsumoto, Outa Uryu, Yoichi Hayakawa
      Growth-blocking peptide (GBP) and stress-responsive peptide (SRP) are insect cytokines whose expression levels are elevated by various stressful conditions such as parasitization and high or low temperatures. Both GBP and SRP are synthesized as precursors and released into the hemolymph, where they are enzymatically processed to active peptides. Injection of active GBP or SRP into early last instar larvae elicits a reduction in feeding and consequent growth retardation in the armyworm Mythimna separata. Although such functions are thought to benefit insects under stressful conditions by affecting their physiologies and behaviors, the relationship between GBP and SRP remains elusive. Here we show that heat stress-induced reactive oxygen species (ROS) elevated hemolymph GBP, which activated SRP transcription and increased the SRP concentration in the hemolymph. Injection of both GBP and SRP elevated hemolymph antioxidant levels. We found that simultaneous increases in both active cytokines occurred in the larval hemolymph from 2 to 3 h after heat stress or H2O2 injection, suggesting a synergic action of the two factors. This speculation was confirmed by demonstrating that co-injection of GBP and SRP caused a more severe reduction in appetite and growth retardation than injection of an individual peptide alone. However, injection of GBP together with SRP did not elevate SRP expression at all, indicating the effect of negative feedback regulation. Furthermore, SRP RNAi larvae showed higher body weights compared to controls, and GBP-induced growth retardation was partially abrogated in SRP RNAi larvae. These results led us to conclude that GBP is an upstream cytokine in the regulation of SRP expression and that these cytokines synergistically retard larval growth by repressing feeding activities when insects are exposed to stress conditions.
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      PubDate: 2018-04-26T03:26:00Z
      DOI: 10.1016/j.ibmb.2018.04.002
       
  • Odorant-binding protein-based identification of natural spatial repellents
           for the African malaria mosquito Anopheles gambiae
    • Authors: Thomas Kröber; Konstantinos Koussis; Martine Bourquin; Panagiota Tsitoura; Maria Konstantopoulou; Taiwo Sam Awolola; Francesca R. Dani; Huili Qiao; Paolo Pelosi; Kostas Iatrou; Patrick M. Guerin
      Abstract: Publication date: Available online 12 April 2018
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Thomas Kröber, Konstantinos Koussis, Martine Bourquin, Panagiota Tsitoura, Maria Konstantopoulou, Taiwo Sam Awolola, Francesca R. Dani, Huili Qiao, Paolo Pelosi, Kostas Iatrou, Patrick M. Guerin
      There is increasing interest in the development of effective mosquito repellents of natural origin to reduce transmission of diseases such as malaria and yellow fever. To achieve this we have employed an in vitro competition assay involving odorant-binding proteins (OBPs) of the malaria mosquito, Anopheles gambiae, with a predominantly female expression bias to identify plant essential oils (EOs) containing bioactive compounds that target mosquito olfactory function. EOs and their fractions capable of binding to such OBPs displayed repellence against female mosquitoes in a laboratory repellence assay. Repelling EOs were subjected to gas chromatographic analysis linked to antennogram (EAG) recordings from female A. gambiae to identify the biologically active constituents. Among these compounds cumin alcohol, carvacrol, ethyl and butyl cinnamate proved as effective as DEET at an equivalent dose in the repellence assay, and combinations of carvacrol with either butyl cinnamate or cumin alcohol proved to be significantly more effective than DEET in the assay. When tested as spatial repellents in experimental shelters housing sleeping humans in northern Nigeria a binary mixture of carvacrol plus cumin alcohol caused mosquitoes to leave shelters in significantly higher numbers to those induced by DEET in female Anopheles spp. and in numbers equivalent to that of DEET in Culex spp. mosquitoes. These findings indicate an approach for the identification of biologically active molecules of natural origin serving as repellents for mosquitoes.
      Graphical abstract image

      PubDate: 2018-04-19T02:45:34Z
      DOI: 10.1016/j.ibmb.2018.03.008
       
  • Hyperactive piggyBac transposase improves transformation efficiency in
           diverse insect species
    • Authors: Kolja N. Eckermann; Hassan M.M. Ahmed; Mohammad KaramiNejadRanjbar; Stefan Dippel; Christian E. Ogaugwu; Peter Kitzmann; Musa D. Isah; Ernst A. Wimmer
      Abstract: Publication date: Available online 10 April 2018
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Kolja N. Eckermann, Hassan M.M. Ahmed, Mohammad KaramiNejadRanjbar, Stefan Dippel, Christian E. Ogaugwu, Peter Kitzmann, Musa D. Isah, Ernst A. Wimmer
      Even in times of advanced site-specific genome editing tools, the improvement of DNA transposases is still on high demand in the field of transgenesis: especially in emerging model systems where evaluated integrase landing sites have not yet been created and more importantly in non-model organisms such as agricultural pests and disease vectors, in which reliable sequence information and genome annotations are still pending. In fact, random insertional mutagenesis is essential to identify new genomic locations that are not influenced by position effects and thus can serve as future stable transgene integration sites. In this respect, a hyperactive version of the most widely used piggyBac transposase (PBase) has been engineered. The hyperactive version (hyPBase) is currently available with the original insect codon-based coding sequence ( i hyPBase) as well as in a mammalian codon-optimized ( m hyPBase) version. Both facilitate significantly higher rates of transposition when expressed in mammalian in vitro and in vivo systems compared to the classical PBase at similar protein levels. Here we demonstrate that the usage of helper plasmids encoding the hyPBase - irrespective of the codon-usage - also strikingly increases the rate of successful germline transformation in the Mediterranean fruit fly (Medfly) Ceratitis capitata, the red flour beetle Tribolium castaneum, and the vinegar fly Drosophila melanogaster. hyPBase-encoding helpers are therefore highly suitable for the generation of transgenic strains of diverse insect orders. Depending on the species, we achieved up to 15-fold higher germline transformation rates compared to PBase and generated hard to obtain transgenic T. castaneum strains that express constructs affecting fitness and viability. Moreover, previously reported high sterility rates supposedly caused by hyPBase (iPB7), encoded by i hyPBase, could not be confirmed by our study. Therefore, we value hyPBase as an effective genetic engineering tool that we highly recommend for insect transgenesis.
      Graphical abstract image

      PubDate: 2018-04-19T02:45:34Z
      DOI: 10.1016/j.ibmb.2018.04.001
       
  • The expression of three opsin genes and phototactic behavior of Spodoptera
           exigua (Lepidoptera: Noctuidae): evidence for visual function of opsin in
           phototaxis
    • Authors: Yan-Jun Liu; Shuo Yan; Zhong-Jian Shen; Zhen Li; Xin-Fang Zhang; Xiao-Ming Liu; Qing-Wen Zhang; Xiao-Xia Liu
      Abstract: Publication date: Available online 4 April 2018
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Yan-Jun Liu, Shuo Yan, Zhong-Jian Shen, Zhen Li, Xin-Fang Zhang, Xiao-Ming Liu, Qing-Wen Zhang, Xiao-Xia Liu
      Phototaxis in nocturnal moths is widely utilized to control pest populations in practical production. However, as an elusive behavior, phototactic behavior is still not well understood. Determination of whether the opsin gene plays a key role in phototaxis is an interesting topic. This study was conducted to analyze expression levels and biological importance of three opsin genes (Se-uv, Se-bl, and Se-lw) and phototactic behavior of Spodoptera exigua. The three opsin genes exhibited higher expression levels during daytime, excluding Se-bl in females, whose expression tended to increase at night. And cycling of opsin gene levels tended to be upregulated at night, although the magnitude of increase in females was lower than that in males exposed to constant darkness. The results of western blotting were consistent with those of qRT-PCR. Furthermore, opsin gene expression was not influenced by light exposure during the scotophase, excluding Se-uv in males, and tended to be downregulated by starvation in females and copulation in both female and male moths. To determine the relationship between opsin gene expression and phototactic behavior, Se-lw was knocked down by RNA interference. Moths with one opsin gene knocked down showed enhanced expression of the other two opsin genes, which may play important roles in compensation in vision. The Se-lw-knockdown moths exhibited reduced phototactic efficiency to green light, suggesting that Se-LW contributes to phototaxis, and increases phototactic efficiency to green light. Our finding provides a sound theoretical basis for further investigation of visual expression pattern and phototactic mechanisms in nocturnal moths.
      Graphical abstract image

      PubDate: 2018-04-19T02:45:34Z
      DOI: 10.1016/j.ibmb.2018.03.006
       
  • A polydnavirus-encoded ANK protein has a negative impact on
           steroidogenesis and development
    • Authors: Marilena Ignesti; Rosalba Ferrara; Patrizia Romani; Luca Valzania; Giulia Serafini; Francesco Pennacchio; Valeria Cavaliere; Giuseppe Gargiulo
      Abstract: Publication date: Available online 17 March 2018
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Marilena Ignesti, Rosalba Ferrara, Patrizia Romani, Luca Valzania, Giulia Serafini, Francesco Pennacchio, Valeria Cavaliere, Giuseppe Gargiulo
      Polydnaviruses (PDV) are viral symbionts associated with ichneumonid and braconid wasps parasitizing moth larvae, which are able to disrupt the host immune response and development, as well as a number of other physiological pathways. The immunosuppressive role of PDV has been more intensely investigated, while very little is known about the PDV-encoded factors disrupting host development. Here we address this research issue by further expanding the functional analysis of ankyrin genes encoded by the bracovirus associated with Toxoneuron nigriceps (Hymenoptera, Braconidae). In a previous study, using Drosophila melanogaster as experimental model system, we demonstrated the negative impact of TnBVank1 impairing the ecdysone biosynthesis by altering endocytic traffic in prothoracic gland cells. With a similar approach here we demonstrate that another member of the viral ank gene family, TnBVank3, does also contribute to the disruption of ecdysone biosynthesis, but with a completely different mechanism. We show that its expression in Drosophila prothoracic gland (PG) blocks the larval-pupal transition by impairing the expression of steroidogenic genes. Furthermore, we found that TnBVank3 affects the expression of genes involved in the insulin/TOR signaling and the constitutive activation of the insulin pathway in the PG rescues the pupariation impairment. Collectively, our data demonstrate that TnBVANK3 acts as a virulence factor by exerting a synergistic and non-overlapping function with TnBVANK1 to disrupt the ecdysone biosynthesis.
      Graphical abstract image

      PubDate: 2018-03-18T20:31:17Z
      DOI: 10.1016/j.ibmb.2018.03.003
       
  • On the biosynthetic origin of carminic acid
    • Authors: Silas A. Rasmussen; Kenneth T. Kongstad; Paiman Khorsand-Jamal; Rubini Maya Kannangara; Majse Nafisi; Alex Van Dam; Mads Bennedsen; Bjørn Madsen; Finn Okkels; Charlotte H. Gotfredsen; Dan Staerk; Ulf Thrane; Uffe H. Mortensen; Thomas O. Larsen; Rasmus J.N. Frandsen
      Abstract: Publication date: Available online 16 March 2018
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Silas A. Rasmussen, Kenneth T. Kongstad, Paiman Khorsand-Jamal, Rubini Maya Kannangara, Majse Nafisi, Alex Van Dam, Mads Bennedsen, Bjørn Madsen, Finn Okkels, Charlotte H. Gotfredsen, Dan Staerk, Ulf Thrane, Uffe H. Mortensen, Thomas O. Larsen, Rasmus J.N. Frandsen
      The chemical composition of the scale insect Dactylopius coccus was analyzed with the aim to discover new possible intermediates in the biosynthesis of carminic acid. UPLC-DAD/HRMS analyses of fresh and dried insects resulted in the identification of three novel carminic acid analogues and the verification of several previously described intermediates. Structural elucidation revealed that the three novel compounds were desoxyerythrolaccin-O-glucosyl (DE-O-Glcp ), 5,6-didehydroxyerythrolaccin 3-O-β-D-glucopyranoside (DDE-3-O-Glcp ), and flavokermesic acid anthrone (FKA). The finding of FKA in D. coccus provides solid evidence of a polyketide, rather than a shikimate, origin of coccid pigments. Based on the newly identified compounds, we present a detailed biosynthetic scheme that accounts for the formation of carminic acid (CA) in D. coccus and all described coccid pigments which share a flavokermesic acid (FK) core. Detection of coccid pigment intermediates in members of the Planococcus (mealybugs) and Pseudaulacaspis genera shows that the ability to form these pigments is taxonomically more widely spread than previously documented. The shared core-FK-biosynthetic pathway and wider taxonomic distribution suggests a common evolutionary origin for the trait in all coccid dye producing insect species.
      Graphical abstract image

      PubDate: 2018-03-18T20:31:17Z
      DOI: 10.1016/j.ibmb.2018.03.002
       
  • HR38, an ortholog of NR4A family nuclear receptors, mediates
           20-hydroxyecdysone regulation of carbohydrate metabolism during mosquito
           reproduction
    • Authors: Dujuan Dong; Yang Zhang; Vlastimil Smykal; Lin Ling; Alexander S. Raikhel
      Abstract: Publication date: Available online 9 March 2018
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Dujuan Dong, Yang Zhang, Vlastimil Smykal, Lin Ling, Alexander S. Raikhel
      The Aedes aegypti mosquito is the principal vector for many dangerous human viral diseases. Carbohydrate metabolism (CM) is essential for supplying the energy necessary for host seeking, blood digestion and rapid egg development of this vector insect. The steroid hormone 20-hydroxyecdysone (20E) and the ecdysone receptor (EcR) are important regulators of CM, coordinating it with female reproductive events. We report here that the NR4A nuclear receptor AHR38 plays a critical role in mediating these actions of 20E and EcR. AHR38 RNA interference (RNAi) depletion in female mosquitoes blocked the transcriptional activation of CM genes encoding phosphoglucomutase (PGM) and trehalose-6-phophate synthase (TPS); it caused an increase of glycogen accumulation and a decrease of the circulating sugar trehalose. This treatment also resulted in a dramatic reduction in fecundity. Considering that these phenotypes resulting from AHR38 RNAi depletion are similar to those of EcR RNAi, we investigated a possible connection between these transcription factors in CM regulation. EcR RNAi inhibits the AHR38 gene expression. Moreover, the 20E-induced EcR complex directly activates AHR38 by binding to the ecdysone response element (EcRE) in the upstream regulatory region of this gene. The present work has implicated AHR38 in the 20E-mediated control of CM and provided new insight into mechanisms of 20E regulation of metabolism during female mosquito reproduction.
      Graphical abstract image

      PubDate: 2018-03-18T20:31:17Z
      DOI: 10.1016/j.ibmb.2018.02.003
       
  • JH biosynthesis and hemolymph titers in adult male Aedes aegypti
           mosquitoes
    • Authors: Marcela Nouzova; Veronika Michalkova; Salvador Hernández-Martínez; Crisalejandra Rivera-Perez; Cesar E. Ramirez; Francisco Fernandez-Lima; Fernando G. Noriega
      Abstract: Publication date: Available online 9 March 2018
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Marcela Nouzova, Veronika Michalkova, Salvador Hernández-Martínez, Crisalejandra Rivera-Perez, Cesar E. Ramirez, Francisco Fernandez-Lima, Fernando G. Noriega
      Juvenile hormone (JH) is a major hormonal regulator in insects. In Aedes aegypti females, JH signals the completion of the ecdysis to the adult stage and initiates reproductive processes. Although the regulation of JH synthesis and titer in Ae. aegypti females has been extensively studied, relatively little is known about changes of JH synthesis and titers in male mosquitoes, as well as on the roles of JH controlling male reproductive biology. A better understanding of male mosquito reproductive biology, including an improved knowledge of the hormonal control of reproduction, could increase the likelihood of success of male-targeting vector control programs. Using a high performance liquid chromatography coupled to electrospray tandem mass spectrometry method, we measured JH biosynthesis and hemolymph levels in male mosquitoes during pupal and adult stages. Our results revealed tightly concomitant changes in JH biosynthesis and JH hemolymph titers. Synthesis of JH III was very low in late pupae, significantly increased during the first 24 h after adult eclosion, and then remained relatively constant during the first six days after adult eclosion. Feeding high sugar diets resulted in an increase of JH synthesis and titers, and starvation significantly decreased JH synthesis, but this effect could be reversed by changing the males back to a high sugar diet. JH synthesis rates were similar in virgin and mated males, but hemolymph JH levels were different in well-nourished virgin and mated males. Starvation resulted in a significant reduction in insemination rates; with well-nourished males inseminating 2 times more females than water-fed. Giving a 20% sugar meal for 24 h to those mosquitoes that were previously starved for 6 days, caused a significant rise in insemination rates, restoring them to levels similar to those recorded for 20% fed males. These results suggest that nutrition plays a role on male fecundity, and this effect might be mediated by JH.
      Graphical abstract image

      PubDate: 2018-03-18T20:31:17Z
      DOI: 10.1016/j.ibmb.2018.02.005
       
  • Inducible glutathione S-transferase (IrGST1) from the tick Ixodes ricinus
           is a haem-binding protein
    • Authors: Jan Perner; Jan Kotál; Tereza Hatalová; Veronika Urbanová; Pavla Bartošová-Sojková; Peter M. Brophy; Petr Kopáček
      Abstract: Publication date: Available online 9 March 2018
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Jan Perner, Jan Kotál, Tereza Hatalová, Veronika Urbanová, Pavla Bartošová-Sojková, Peter M. Brophy, Petr Kopáček
      Blood-feeding parasites are inadvertently exposed to high doses of potentially cytotoxic haem liberated upon host blood digestion. Detoxification of free haem is a special challenge for ticks, which digest haemoglobin intracellularly. Ticks lack a haem catabolic mechanism, mediated by haem oxygenase, and need to dispose of vast majority of acquired haem via its accumulation in haemosomes. The knowledge of individual molecules involved in the maintenance of haem homeostasis in ticks is still rather limited. RNA-seq analyses of the Ixodes ricinus midguts from blood- and serum-fed females identified an abundant transcript of glutathione S-transferase (gst) to be substantially up-regulated in the presence of red blood cells in the diet. Here, we have determined the full sequence of this encoding gene, ir-gst1, and found that it is homologous to the delta-/epsilon-class of GSTs. Phylogenetic analyses across related chelicerates revealed that only one clear IrGST1 orthologue could be found in each available transcriptome from hard and soft ticks. These orthologues create a well-supported clade clearly separated from other ticks' or mites’ delta-/epsilon-class GSTs and most likely evolved as an adaptation to tick blood-feeding life style. We have confirmed that IrGST1 expression is induced by dietary haem(oglobin), and not by iron or other components of host blood. Kinetic properties of recombinant IrGST1 were evaluated by model and natural GST substrates. The enzyme was also shown to bind haemin in vitro as evidenced by inhibition assay, VIS spectrophotometry, gel filtration, and affinity chromatography. In the native state, IrGST1 forms a dimer which further polymerises upon binding of excessive amount of haemin molecules. Due to susceptibility of ticks to haem as a signalling molecule, we speculate that the expression of IrGST1 in tick midgut functions as intracellular buffer of labile haem pool to ameliorate its cytotoxic effects upon haemoglobin intracellular hydrolysis.
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      PubDate: 2018-03-18T20:31:17Z
      DOI: 10.1016/j.ibmb.2018.02.002
       
  • Targeting symbiosis-related insect genes by RNAi in the pea aphid-Buchnera
           symbiosis
    • Authors: Seung Ho Chung; Xiangfeng Jing; Yuan Luo; Angela E. Douglas
      Abstract: Publication date: Available online 8 March 2018
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Seung Ho Chung, Xiangfeng Jing, Yuan Luo, Angela E. Douglas
      The growth and reproduction of phloem sap-feeding insects requires the sustained function of intracellular bacteria localized in specialized cells known as bacteriocytes, giving the potential to target the bacterial symbiosis as a novel strategy for controlling sap-feeding insect pests. We focused on two genes in the pea aphid Acyrthosiphon pisum, amiD and ldcA1, which were acquired horizontally from bacteria and have the annotated function to degrade immunogenic bacterial peptidoglycan. We hypothesized that AmiD and LdcA1 function to eliminate peptidoglycan fragments released by the bacterial symbiont Buchnera inhabiting the bacteriocytes, thereby protecting the Buchnera from host attack. Consistent with this hypothesis, expression of amiD and ldcA1 is enriched in bacteriocytes and varies significantly with aphid age, conforming to an inverse curvilinear relationship for amiD and negative linear relationship for ldcA1. RNAi against amiD and ldcA1 administered orally to larval pea aphids caused a significant reduction in Buchnera abundance and activity, accompanied by depressed aphid growth rates. For RNAi experiments, the aphids were co-administered with dsRNA against an aphid nuclease nuc1, protecting the dsRNA against non-specific degradation. These experiments demonstrate that selective suppression of insect symbiosis-related gene function can reduce the performance of an insect pest. Phylogenetic analysis identified amiD and ldcA1 in sequenced genomes of other aphid species, and amiD in related groups of phloem-feeding insects, offering the opportunity for specific controls against a range of insect pests.
      Graphical abstract image

      PubDate: 2018-03-18T20:31:17Z
      DOI: 10.1016/j.ibmb.2018.02.004
       
  • A deep insight into the male and female sialotranscriptome of adult Culex
           tarsalis mosquitoes
    • Authors: José M.C. Ribeiro; Ines Martin-Martin; Fernando R. Moreira; Kristen A. Bernard; Eric Calvo
      Abstract: Publication date: Available online 8 March 2018
      Source:Insect Biochemistry and Molecular Biology
      Author(s): José M.C. Ribeiro, Ines Martin-Martin, Fernando R. Moreira, Kristen A. Bernard, Eric Calvo
      Previously, a Sanger-based sialotranscriptome analysis of adult female Culex tarsalis was published based on ∼2000 ESTs. During the elapsed 7.5 years, pyrosequencing has been discontinued and Illumina sequences have increased considerable in size and decreased in price. We here report an Illumina-based sialotranscriptome that allowed finding the missing apyrase from the salivary transcriptome of C. tarsalis, to determine several full-length members of the 34–62 kDa family, when a single EST has been found previously, in addition to identifying many salivary families with lower expression levels that were not detected previously. The use of multiple libraries including salivary glands and carcasses from male and female organisms allowed for an unprecedented insight into the tissue specificity of transcripts, and in this particular case permitting identification of transcripts putatively associated with blood feeding, when exclusive of female salivary glands, or associated with sugar feeding, when transcripts are found upregulated in both male and female glands.
      Graphical abstract image

      PubDate: 2018-03-18T20:31:17Z
      DOI: 10.1016/j.ibmb.2018.03.001
       
  • Tripeptides derived from reactive centre loop of potato type II protease
           inhibitors selectively inhibit midgut proteases of insect, Helicoverpa
           armigera
    • Authors: Nidhi S. Saikhedkar; Rakesh S. Joshi; Ashiwini S. Bhoite; Radhika Mohandasan; Amit Kumar Yadav; Moneesha Fernandes; Kiran A. Kulkarni; Ashok P. Giri
      Abstract: Publication date: Available online 25 February 2018
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Nidhi S. Saikhedkar, Rakesh S. Joshi, Ashiwini S. Bhoite, Radhika Mohandasan, Amit Kumar Yadav, Moneesha Fernandes, Kiran A. Kulkarni, Ashok P. Giri
      Potato type II protease inhibitors (Pin-II PIs) impede the growth of lepidopteran insects by inhibiting serine protease-like enzymes in the larval gut. The three amino acid reactive centre loop (RCL) of these proteinaceous inhibitors is crucial for protease binding and is conserved across the Pin-II family. However, the molecular mechanism and inhibitory potential of the RCL tripeptides in isolation of the native protein has remained elusive. In this study, six peptides corresponding to the RCLs of the predominant Pin-II PIs were identified, synthesized and evaluated for in vitro and in vivo inhibitory activity against serine proteases of the polyphagous insect, Helicoverpa armigera. RCL peptides with sequences PRN, PRY and TRE were found to be potent inhibitors that adversely affected the growth and development of H. armigera. The binding mechanism and differential affinity of the RCL peptides with serine proteases was delineated by crystal structures of complexes of the RCL peptides with trypsin. Residues P1 and P2 of the inhibitors play a crucial role in the interaction and specificity of these inhibitors. Important features of RCL peptides like higher inhibition of insect proteases, enhanced efficacy at alkaline gut pH, longer retention and high stability in insect gut make them suitable molecules for the development of sustainable pest management strategies for crop protection.
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      PubDate: 2018-02-25T17:22:20Z
      DOI: 10.1016/j.ibmb.2018.02.001
       
  • The doublesex gene integrates multi-locus complementary sex determination
           signals in the Japanese ant, Vollenhovia emeryi
    • Authors: Misato Okamoto Miyakawa; Koji Tsuchida; Hitoshi Miyakawa
      Abstract: Publication date: Available online 2 February 2018
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Misato Okamoto Miyakawa, Koji Tsuchida, Hitoshi Miyakawa
      A female diploid, male haploid sex determination system (haplodiploidy) is found in hymenopteran taxa, such as ants, wasps, bees and sawflies. In this system, a single, complementary sex-determination (sl-CSD) locus functions as the primary sex-determination signal. In the taxa that has evolved this system, females and males are heterozygous and hemi/homozygous at the CSD locus, respectively. While the sl-CSD system enables females to alter sex ratios in the nest, it carries a high cost in terms of inbreeding, as individuals that are homozygous at the CSD locus become sterile diploid males. To counter this risk, some of hymenopteran species have evolved a multi-locus CSD (ml-CSD) system, which effectively reduces the proportion of sterile males. However, the mechanism by which these multiple primary signals are integrated and how they affect the terminal sex-differentiation signal of the molecular cascade have not yet been clarified. To resolve these questions, we examined the molecular cascade in the Japanese ant Vollenhovia emeryi, which we previously confirmed has two CSD loci. Here, we showed that the sex-determination gene, doublesex (dsx), which is highly conserved among phylogenetically distant taxa, is responsible for integrating two CSD signals in V. emeryi. After identifying and characterizing dsx, genotypes containing two CSD loci and splicing patterns of dsx were found to correspond to the sexual phenotype, suggesting that two primary signals are integrated into dsx. These findings will facilitate future molecular and functional studies of the sex determination cascade in V. emeryi, and shed light on the evolution and diversification of sex determination systems in insects.
      Graphical abstract image

      PubDate: 2018-02-05T15:52:24Z
      DOI: 10.1016/j.ibmb.2018.01.006
       
  • Identification of yellow gene family in Agrotis ipsilon and functional
           analysis of Aiyellow-y by CRISPR/Cas9
    • Authors: Xi'en Chen; Yanghui Cao; Shuai Zhan; Yong Zhang; Anjiang Tan; Yongping Huang
      Abstract: Publication date: Available online 11 January 2018
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Xi'en Chen, Yanghui Cao, Shuai Zhan, Yong Zhang, Anjiang Tan, Yongping Huang
      The yellow gene family has been identified in several model insects, but yellow genes were poorly identified in non-model insects and the functions of yellow genes are largely unknown. In this study, we identified seven yellow genes in an important agricultural pest Agrotis ipsilon. Each gene encodes a protein containing a major royal jelly domain. Phylogenetic analysis defined these genes as yellow-y, -b, -b2, -c, -d, -e, and –h, respectively. The A. ipsilon yellow genes yellow-b, -b2, and –c were stably expressed in all developmental stages and tissues analyzed, whereas the other four yellow genes had unique expression patterns, suggesting distinct physiological roles of each gene. Using the CRISPR/Cas9 system, we successfully disrupted yellow-y in A. ipsilon and obtained G0 insects with somatic mutations. Unlike the black of wild-type newly hatched larvae and of adults, the mutants were yellow, although in the pupal stage mutant coloration did not differ from wild-type coloration. This phenotype was inherited by G1 offspring. The G0 mutants did not show any growth deficiency compared with control insects; however, a dehydration-like phenotype was observed in newly hatched G1 larvae from sibling crossed mutants. Our results indicate that A. ipsilon yellow-y gene plays a role in body pigmentation and also might function in waterproofing.
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      PubDate: 2018-01-25T15:37:46Z
      DOI: 10.1016/j.ibmb.2018.01.002
       
  • Brochosomins and other novel proteins from brochosomes of leafhoppers
           (Insecta, Hemiptera, Cicadellidae)
    • Authors: Roman Rakitov; Alexander A. Moysa; Arthur T. Kopylov; Sergei A. Moshkovskii; Ralph S. Peters; Karen Meusemann; Bernhard Misof; Christopher H. Dietrich; Kevin P. Johnson; Lars Podsiadlowski; Kimberly K.O. Walden
      Abstract: Publication date: Available online 10 January 2018
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Roman Rakitov, Alexander A. Moysa, Arthur T. Kopylov, Sergei A. Moshkovskii, Ralph S. Peters, Karen Meusemann, Bernhard Misof, Christopher H. Dietrich, Kevin P. Johnson, Lars Podsiadlowski, Kimberly K.O. Walden
      Brochosomes (BS) are secretory granules resembling buckyballs, produced intracellularly in specialized glandular segments of the Malpighian tubules and forming superhydrophobic coatings on the integuments of leafhoppers (Hemiptera, Cicadellidae). Their composition is poorly known. Using a combination of SDS-PAGE, LC-MS/MS, next-generation sequencing (RNAseq) and bioinformatics we demonstrate that the major structural component of BS of the leafhopper Graphocephala fennahi Young is a novel family of 21–40-kDa secretory proteins, referred to herein as brochosomins (BSM), apparently cross-linked by disulfide bonds. At least 28 paralogous BSM were identified in a transcriptome assembly of this species, most of which were detected in BS. Multiple additional BS-associated proteins (BSAP), possibly loosely attached to the outer and inner surfaces of BS, were also identified; some of these were glycine-, tyrosine- and proline-rich. BSM and BSAP together accounted for half of the 100 most expressed transcripts in the Malpighian tubules of G. fennahi. Except for several minor BSAP possibly related to cyclases, BSM and BSAP had no homologs among known proteins, thus representing taxonomically restricted gene families (orphans). Searching in 50 whole-body transcriptome assemblies of Hemiptera found homologs of BSM in representatives of all five families of the superfamily Membracoidea (Cicadellidae, Myerslopiidae, Aetalionidae, Membracidae, and Melizoderidae), but not in other lineages. Among the identified proteins only BSM were shared in common between all 17 surveyed leafhoppers known to produce BS. Combined CHN elemental and aminoacid analyses estimated the total protein content of BS from the integument of G. fennahi to be 60–70%.
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      PubDate: 2018-01-25T15:37:46Z
      DOI: 10.1016/j.ibmb.2018.01.001
       
  • MicroRNA-14 regulates larval development time in Bombyx mori
    • Authors: Zulian Liu; Lin Ling; Jun Xu; Baosheng Zeng; Yongping Huang; Peng Shang; Anjiang Tan
      Abstract: Publication date: Available online 27 December 2017
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Zulian Liu, Lin Ling, Jun Xu, Baosheng Zeng, Yongping Huang, Peng Shang, Anjiang Tan
      MicroRNAs (miRNA) regulate multiple physiological processes including development and metamorphosis in insects. In the current study, we demonstrate that a conserved invertebrate miRNA-14 (miR-14) plays an important role in ecdysteroid regulated development in the silkworm Bombyx mori, a lepidopteran model insect. Ubiquitous transgenic overexpression of miR-14 using the GAL4/UAS system resulted in delayed silkworm larval development and smaller body size of larva and pupa with decrease in ecdysteriod titers. On the contrary, miR-14 disruption using the transgenic CRISPR/Cas9 system led to a precocious wandering stage with increase in ecdysteriod titers. We identified that the hormone receptor E75 (E75) and the ecdysone receptor isoform B (ECR-B), which both serve as essential mediators in the ecdysone signaling pathway, as putative target genes of miR-14 by in silico target prediction. Dual-luciferase reporter assays confirmed the binding of miR-14 to the 3′UTRs of E75 and ECR-B in a mammalian HEK293T cell line. Furthermore, transcription levels of E75 and ECR-B were significantly affected in both miR-14 overexpression and knockout transgenic animals. Taken together, our data suggested that the canonical invertebrate miR-14 is a general regulator in maintaining ecdysone homeostasis for normal development and metamorphosis in B. mori.
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      PubDate: 2018-01-03T10:58:17Z
      DOI: 10.1016/j.ibmb.2017.12.009
       
  • Juvenile hormone-independent function of Krüppel homolog 1 in early
           development of water flea Daphnia pulex
    • Authors: Hitoshi Miyakawa; Minae Watanabe; Marina Araki; Yukiko Ogino; Shinichi Miyagawa; Taisen Iguchi
      Pages: 12 - 18
      Abstract: Publication date: February 2018
      Source:Insect Biochemistry and Molecular Biology, Volume 93
      Author(s): Hitoshi Miyakawa, Minae Watanabe, Marina Araki, Yukiko Ogino, Shinichi Miyagawa, Taisen Iguchi
      Elaborate regulation of insect metamorphosis is the consequence of physiological cooperation among multiple endocrine factors such as juvenile hormones (JHs) and ecdysteroids. Hormone-induced transcription factors play important roles in substantive interactions between hormonal signaling pathways. In insects, zinc finger transcription factor Krüppel homolog 1 (Kr-h1) is a key gene of the endocrine signaling pathway in which it is directly upregulated by JH receptor Methoprene-tolerant (Met) in the presence of JH and then regulates multiple downstream factors, including components of the ecdysteroid signaling pathway. Although JH also plays a role in various biological phenomena in other arthropod species, little is known about the molecular basis of the JH signaling pathway. Here we cloned Kr-h1 from a branchiopod crustacean, Daphnia pulex, (DappuKr-h1) and analyzed its expression profile and developmental function together with consideration of its relationship to the JH signaling pathway. We suggest that DappuKr-h1 lacks JH responsiveness and regulatory relationship with the JH receptor. Moreover our loss-of-function analysis revealed that maternal mRNA of DappuKr-h1 plays a critical role in early development independent from the JH signaling pathway. These findings provide insights about whether and how the JH signaling pathway influenced evolution, leading to greater diversity in phylum Arthropoda.
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      PubDate: 2017-12-24T15:36:02Z
      DOI: 10.1016/j.ibmb.2017.12.007
      Issue No: Vol. 93 (2017)
       
  • 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.
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      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.
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      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.
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      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.
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      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.
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      PubDate: 2017-12-07T13:22:28Z
      DOI: 10.1016/j.ibmb.2017.11.009
      Issue No: Vol. 92 (2017)
       
  • Environmental and hormonal control of body color polyphenism in
           late-instar desert locust nymphs: Role of the yellow protein
    • Authors: Ryohei Sugahara; Seiji Tanaka; Akiya Jouraku; Takahiro Shiotsuki
      Pages: 5 - 11
      Abstract: Publication date: Available online 14 December 2017
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Ryohei Sugahara, Seiji Tanaka
      Locusts show body color polyphenism that is considered to be an adaptation to various biotic and abiotic environmental changes. In Schistocerca gregaria, wild-type late-instar nymphs growing under crowded conditions (gregarious form) develop yellow and black body coloration, whereas they assume various body colors under isolated conditions (solitarious form). Black and green body colorations are induced by the neuropeptide corazonin (Crz) and juvenile hormone (JH), respectively. To characterize the molecular mechanisms controlling body color polyphenism, we investigated factors influencing body coloration in S. gregaria. We report here that yellow body coloration in the last nymphal instar is caused by the yellow protein of the takeout family (YPT) in this locust. YPT transcription was enhanced under high-temperature conditions during which the nymphs turned bright yellow and had little black patterning. RNAi-mediated YPT knockdown suppressed the appearance of yellow individuals and yellow staining in the exuviae. In albino nymphs, injection of JH induced yellow and green coloration and enhanced the YPT expression levels in both yellow and green individuals. YPT knockdown also suppressed yellow staining in the exuviae but did not prevent the appearance of yellow individuals. Therefore, another factor or pigment may contribute to the observed yellow body color. Injection of Crz into wild-type nymphs caused darkening and suppressed yellowing and YPT expression at high temperatures. Thus, Crz signaling could inhibit yellowing by suppressing YPT expression. Rearing cup substrate color significantly influenced YPT expression in albino nymphs both under isolated and crowded conditions. In contrast, substrate color affected YPT expression in wild-type nymphs only under isolated conditions. From these results, we conclude that YPT is an important factor in the control of body color polyphenism in S. gregaria, and its expression is influenced by temperature, JH, Crz, and substrate color of the developmental environment.
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      PubDate: 2017-12-24T15:36:02Z
      DOI: 10.1016/j.gene.2016.12.028
      Issue No: Vol. 605 (2017)
       
  • Cell lines as models for the study of Cry toxins from Bacillus
           thuringiensis
    • Authors: Mario Soberón; Leivi Portugal; Blanca-Ines Garcia-Gómez; Jorge Sánchez; Janette Onofre; Isabel Gómez; Sabino Pacheco; Alejandra Bravo
      Abstract: Publication date: Available online 19 December 2017
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Mario Soberón, Leivi Portugal, Blanca-Ines Garcia-Gómez, Jorge Sánchez, Janette Onofre, Isabel Gómez, Sabino Pacheco, Alejandra Bravo
      Cell lines have been use extensively for the study of the mode of action of different pore forming toxins produced by different bacterial species. Bacillus thuringiensis Cry toxins are not the exception and their mechanism of action has been analyzed in different cell lines. Here we review the data obtained with different cell lines, including those that are naturally susceptible to the three domain Cry toxins (3d-Cry) and other non-susceptible cell lines that have been transformed with 3d-Cry toxin binding molecules cloned from the susceptible insects. The effects on Cry toxin action after expressing different insect gut proteins, such as glycosyl-phosphatidyl-inositol (GPI) anchored proteins (like alkaline phosphatase (ALP) aminopeptidase (APN)), or trans-membrane proteins (like cadherin (CAD) or ATP-binding cassette subfamily C member 2 (ABCC2) transporter) in cell lines showed that, with few exceptions, expression of GPI-anchored proteins do not correlated with increased susceptibility to the toxin, while the expression of CAD or ABCC2 proteins correlated with induced susceptibility to Cry toxins in the transformed cells lines. Also, that the co-expression of CAD and ABCC2 transporter induced a synergistic effect in the toxicity of 3d-Cry toxins. Overall the data show that in susceptible cell lines, the 3d-Cry toxins induce pore formation that correlates with toxicity. However, the intracellular responses remain controversial since it was shown that the same 3d-Cry toxin in different cell lines activated different responses such as adenylate cyclase-PKA death response or apoptosis. Parasporins are Cry toxins that are toxic to cancer cell lines that have structural similarities with the insecticidal Cry toxins. They belong to the 3d-Cry toxin or to MTX-like Cry toxin families but also show important differences with the insecticidal Cry proteins. Some parasporins are pore-forming toxins, and some activate apoptosis. In this review we summarized the results of the different studies about the Cry toxins mode of action using cultured cell lines and discuss their relation with the studies performed in insect larvae.
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      PubDate: 2017-12-24T15:36:02Z
      DOI: 10.1016/j.ibmb.2017.12.008
       
  • Phylogenetic and functional characterization of ten P450 genes from the
           CYP6AE subfamily of Helicoverpa armigera involved in xenobiotic metabolism
           
    • Authors: Yu Shi; Huidong Wang; Zhi Liu; Shuwen Wu; Yihua Yang; René Feyereisen; Yidong Wu
      Abstract: Publication date: Available online 16 December 2017
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Yu Shi, Huidong Wang, Zhi Liu, Shuwen Wu, Yihua Yang, René Feyereisen, Yidong Wu
      The cotton bollworm, Helicoverpa armigera, is a generalist herbivore widely distributed over the world and is a major lepidopteran pest on cotton. Studies, especially from Asia, show that it relies on cytochrome P450 monooxygenases with broad substrate specificities to protect itself from pesticides. The number of P450s may have expanded in the processes of coping with the wide diversity of phytochemicals that the insect encounters among its numerous host plants. In order to examine the metabolic capabilities of these P450s, we focused here on all ten P450s of the Helicoverpa armigera CYP6AE subfamily, which can be easily induced by plant toxins and pyrethroids. These P450s, along with cytochrome P450 reductase, were heterologously expressed in insect cells and compared functionally. In vitro metabolism showed that all CYP6AE family members can convert esfenvalerate to 4′-hydroxyesfenvalerate efficiently except CYP6AE20. In contrast, none of the recombinant CYP6AE enzymes could metabolise gossypol under our experimental conditions. Epoxidation capabilities were observed in the CYP6AE subfamily, aldrin can be converted to dieldrin at rates up to 0.45 ± 0.04 pmol/min/pmol P450. Seven P450s in this subfamily can metabolise imidacloprid, but with lower efficiency than Bemisia tabaci CYP6CM1vQ. CYP6AE20 had virtually no metabolic competence to these four compounds but could metabolise several model fluorogenic substrates. These results showed the broad substrate spectrum of H. armigera CYP6AE P450s and suggest a limited role of gossypol upon the evolution of H. armigera CYP6AE genes.

      PubDate: 2017-12-24T15:36:02Z
      DOI: 10.1016/j.ibmb.2017.12.006
       
  • Identification of immature stages of phlebotomine sand flies using
           MALDI-TOF MS and mapping of mass spectra during sand fly life cycle
    • Authors: Petr Halada; Kristyna Hlavackova; Vit Dvorak; Petr Volf
      Abstract: Publication date: Available online 14 December 2017
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Petr Halada, Kristyna Hlavackova, Vit Dvorak, Petr Volf
      The aim of the study was to evaluate the potential of matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF MS) for the species identification of sand flies at different developmental stages and map changes in their protein profiles during the course of whole life cycle. Specimens of six different species from laboratory colonies at larval and pupal stages were examined using MALDI-TOF MS. The protein profiles of larvae were stable from the L2 to L4 developmental stages and clearly distinguishable at the species level. In a validation study, 123 larvae of the six species were queried against reference database resulting in 93% correct species identification (log score values higher than 2.0). The spectra generated from sand fly pupae allow species identification as well and surprisingly, in contrast to biting midges and mosquitoes, they did not change during this developmental stage. For adults, thorax was revealed as the optimal body part for sample preparation yielding reproducible spectra regardless age and diet. Only variations were uncovered for freshly engorged females profiles of which were affected by blood signals first two days post bloodmeal. The findings demonstrate that in addition to adult species differentiation MALDI-TOF MS may also serve as a rapid and effective tool for species identification of juvenile stages of phlebotomine sand flies.
      Graphical abstract image

      PubDate: 2017-12-24T15:36:02Z
      DOI: 10.1016/j.ibmb.2017.12.005
       
  • CRISPR/Cas9-mediated knockout of two eye pigmentation genes in the brown
           planthopper, Nilaparvata lugens (Hemiptera: Delphacidae)
    • Authors: Wen-Hua Xue; Nan Xu; Xiao-Bo Yuan; Hao-Hao Chen; Jin-Li Zhang; Sheng-Jie Fu; Chuan-Xi Zhang; Hai-Jun Xu
      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
      DOI: 10.1016/j.ibmb.2017.12.003
       
  • Receptor protein of Lysinibacillus sphaericus mosquito-larvicidal toxin
           displays amylomaltase activity
    • Authors: Mahima Sharma; Gagan D. Gupta; Vinay Kumar
      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
      DOI: 10.1016/j.ibmb.2017.12.002
       
  • 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.
      Graphical abstract image

      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
       
  • 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
       
 
 
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