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  Subjects -> BIOLOGY (Total: 2912 journals)
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BIOCHEMISTRY (217 journals)                  1 2 3     

AAPS PharmSciTech     Hybrid Journal   (Followers: 7)
Acetic Acid Bacteria     Open Access   (Followers: 1)
ACS Central Science     Hybrid Journal  
ACS Chemical Biology     Full-text available via subscription   (Followers: 159)
ACS Chemical Neuroscience     Full-text available via subscription   (Followers: 16)
Acta Crystallographica Section D : Biological Crystallography     Hybrid Journal   (Followers: 11)
Acta Crystallographica Section F: Structural Biology Communications     Hybrid Journal   (Followers: 6)
Advances and Applications in Bioinformatics and Chemistry     Open Access   (Followers: 9)
Advances in Biological Chemistry     Open Access   (Followers: 6)
Advances in Carbohydrate Chemistry and Biochemistry     Full-text available via subscription   (Followers: 10)
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: 12)
African Journal of Biochemistry Research     Open Access   (Followers: 1)
African Journal of Chemical Education     Open Access   (Followers: 1)
Alkaloids: Chemical and Biological Perspectives     Full-text available via subscription   (Followers: 4)
American Journal of Biochemistry     Open Access   (Followers: 7)
American Journal of Biochemistry and Biotechnology     Open Access   (Followers: 73)
American Journal of Biochemistry and Molecular Biology     Open Access   (Followers: 11)
American Journal of Polymer Science     Open Access   (Followers: 22)
Amino Acids     Hybrid Journal   (Followers: 6)
Analytical Biochemistry     Hybrid Journal   (Followers: 75)
Annals of Clinical Biochemistry     Hybrid Journal   (Followers: 1)
Annual Review of Biochemistry     Full-text available via subscription   (Followers: 37)
Annual Review of Chemical and Biomolecular Engineering     Full-text available via subscription   (Followers: 10)
Applied Biochemistry and Biotechnology     Hybrid Journal   (Followers: 20)
Applied Biochemistry and Microbiology     Hybrid Journal   (Followers: 9)
Applied Organometallic Chemistry     Hybrid Journal   (Followers: 4)
Archives of Biochemistry and Biophysics     Hybrid Journal   (Followers: 10)
Archives of Insect Biochemistry and Physiology     Hybrid Journal   (Followers: 1)
Archives Of Physiology And Biochemistry     Hybrid Journal   (Followers: 1)
Asian Journal of Biochemistry     Open Access   (Followers: 1)
Asian Journal of Biomedical and Pharmaceutical Sciences     Open Access   (Followers: 2)
Avicenna Journal of Medical Biochemistry     Open Access  
Bangladesh Journal of Medical Biochemistry     Open Access   (Followers: 2)
BBA Clinical     Open Access  
BBR : Biochemistry and Biotechnology Reports     Open Access   (Followers: 4)
Biocatalysis     Open Access  
Biochemical and Biophysical Research Communications     Hybrid Journal   (Followers: 14)
Biochemical and Molecular Medicine     Full-text available via subscription   (Followers: 5)
Biochemical Compounds     Open Access  
Biochemical Engineering Journal     Hybrid Journal   (Followers: 9)
Biochemical Genetics     Hybrid Journal   (Followers: 3)
Biochemical Journal     Full-text available via subscription   (Followers: 18)
Biochemical Pharmacology     Hybrid Journal   (Followers: 6)
Biochemical Society Transactions     Full-text available via subscription   (Followers: 3)
Biochemical Systematics and Ecology     Hybrid Journal   (Followers: 4)
Biochemistry     Full-text available via subscription   (Followers: 158)
Biochemistry & Pharmacology : Open Access     Open Access   (Followers: 1)
Biochemistry & Physiology : Open Access     Open Access  
Biochemistry (Moscow)     Hybrid Journal   (Followers: 3)
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 Cell Biology     Full-text available via subscription   (Followers: 9)
Biochemistry and Molecular Biology Education     Hybrid Journal   (Followers: 3)
Biochemistry and Molecular Biology of Fishes     Full-text available via subscription   (Followers: 1)
Biochemistry Research International     Open Access   (Followers: 5)
Biochimica et Biophysica Acta (BBA) - Molecular and Cell Biology of Lipids     Hybrid Journal   (Followers: 4)
Biochimica et Biophysica Acta (BBA) - Molecular Basis of Disease     Hybrid Journal   (Followers: 16)
Biochimica et Biophysica Acta (BBA) - Molecular Cell Research     Hybrid Journal   (Followers: 5)
Biochimie     Hybrid Journal   (Followers: 5)
Bioconjugate Chemistry     Full-text available via subscription   (Followers: 15)
BioDrugs     Full-text available via subscription   (Followers: 9)
Bioelectrochemistry     Hybrid Journal   (Followers: 2)
Biofuels     Hybrid Journal   (Followers: 11)
Biogeochemistry     Hybrid Journal   (Followers: 10)
BioInorganic Reaction Mechanisms     Hybrid Journal   (Followers: 1)
Biokemistri     Open Access  
Biological Chemistry     Partially Free   (Followers: 12)
Biomaterials Research     Open Access  
Biomedicines     Open Access   (Followers: 1)
BioMolecular Concepts     Hybrid Journal   (Followers: 2)
Bioscience, Biotechnology, and Biochemistry     Hybrid Journal   (Followers: 7)
Biosimilars     Open Access   (Followers: 1)
Biotechnology and Applied Biochemistry     Hybrid Journal   (Followers: 23)
BMC Biochemistry     Open Access   (Followers: 12)
Bulletin of University of Agricultural Sciences and Veterinary Medicine Cluj-Napoca : Food Science and Technology     Open Access  
Carbohydrate Polymers     Hybrid Journal   (Followers: 9)
Cell Biochemistry and Biophysics     Hybrid Journal   (Followers: 5)
Cell Biochemistry and Function     Hybrid Journal   (Followers: 4)
Cellular Physiology and Biochemistry     Open Access   (Followers: 3)
Central European Journal of Chemistry     Hybrid Journal   (Followers: 6)
ChemBioChem     Hybrid Journal   (Followers: 3)
Chemical and Biological Technologies for Agriculture     Open Access  
Chemical Biology & Drug Design     Hybrid Journal   (Followers: 22)
Chemical Engineering Journal     Hybrid Journal   (Followers: 24)
Chemical Senses     Hybrid Journal   (Followers: 1)
Chemical Speciation and Bioavailability     Open Access   (Followers: 1)
Chemico-Biological Interactions     Hybrid Journal   (Followers: 3)
Chemistry & Biodiversity     Hybrid Journal   (Followers: 5)
Chemistry & Biology     Full-text available via subscription   (Followers: 19)
Chemistry and Ecology     Hybrid Journal   (Followers: 1)
ChemTexts     Hybrid Journal  
Clinical Biochemist Reviews     Full-text available via subscription   (Followers: 1)
Clinical Biochemistry     Hybrid Journal   (Followers: 4)
Clinical Chemistry and Laboratory Medicine     Hybrid Journal   (Followers: 10)
Clinical Lipidology     Full-text available via subscription  
Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology     Hybrid Journal   (Followers: 4)
Comparative Biochemistry and Physiology Part B: Biochemistry and Molecular Biology     Hybrid Journal   (Followers: 1)
Comparative Biochemistry and Physiology Part C: Toxicology & Pharmacology     Hybrid Journal   (Followers: 5)
Comparative Biochemistry and Physiology Part D: Genomics and Proteomics     Hybrid Journal   (Followers: 2)

        1 2 3     

Journal Cover Insect Biochemistry and Molecular Biology
  [SJR: 1.703]   [H-I: 75]   [4 followers]  Follow
    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 0965-1748
   Published by Elsevier Homepage  [2801 journals]
  • Photoperiod regulates growth of male accessory glands through juvenile
           hormone signaling in the linden bug, Pyrrhocoris apterus
    • Abstract: Publication date: Available online 28 January 2016
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Veronika Urbanová, Olga Bazalová, Hanka Vaněčková, David Dolezel
      Adult reproductive diapause is characterized by lower behavioral activity, ceased reproduction and absence of juvenile hormone (JH). The role of JH receptor Methoprene-tolerant (Met) in female reproduction is well established; however, its function in male reproductive development and behavior is unclear. In the bean bug, Riptortus pedestris, circadian genes are essential for mediating photoperiodically-dependent growth of the male accessory glands (MAGs). The present study explores the role of circadian genes and JH receptor in male diapause in the linden bug, Pyrrhocoris apterus. These data indicate that circadian factors Clock, Cycle and Cry2 are responsible for photoperiod measurement, whereas Met and and its partner protein Taiman participate in JH reception. Surprisingly, knockdown of the JH receptor neither lowered locomotor activity nor reduced mating behavior of males. These data suggest existence of a parallel, JH-independent or JH-upstream photoperiodic regulation of reproductive behavior.
      Graphical abstract image

      PubDate: 2016-01-30T08:56:07Z
       
  • Quantitative metabolome, proteome and transcriptome analysis of midgut and
           fat body tissues in the mountain pine beetle, Dendroctonus ponderosae
           Hopkins, and insights into pheromone biosynthesis
    • Abstract: Publication date: Available online 12 January 2016
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Christopher I. Keeling, Maria Li, Harpreet K. Sandhu, Hannah Henderson, Macaire Man Saint Yuen, Jörg Bohlmann
      Bark beetles (Coleoptera: Scolytinae) are pests of many forests around the world. The mountain pine beetle (MPB), Dendroctonus ponderosae Hopkins, is a significant pest of western North American pine forests. The MPB is able to overcome the defences of pine trees through pheromone-assisted aggregation that results in a mass attack of host trees. These pheromones, both male and female produced, are believed to be biosynthesized in the midgut and/or fat bodies of these insects. We used metabolite analysis, quantitative proteomics (iTRAQ) and transcriptomics (RNA-seq) to identify proteins and transcripts differentially expressed between sexes and between tissues when treated with juvenile hormone III. Juvenile hormone III induced frontalin biosynthesis in males and trans-verbenol biosynthesis in females, as well as affected the expression of many proteins and transcripts in sex- and tissue-specific ways. Based on these analyses, we identified candidate genes involved in the biosynthesis of frontalin, exo-brevicomin, and trans-verbenol pheromones.
      Graphical abstract image

      PubDate: 2016-01-16T08:36:46Z
       
  • Calcium influx enhances neuropeptide activation of ecdysteroid hormone
           production by mosquito ovaries
    • Abstract: Publication date: Available online 7 January 2016
      Source:Insect Biochemistry and Molecular Biology
      Author(s): David A. McKinney, Jai-Hoon Eum, Animesh Dhara, Michael R. Strand, Mark R. Brown
      A critical step in mosquito reproduction is the ingestion of a blood meal from a vertebrate host. In mosquitoes like Aedes aegypti, blood feeding stimulates the release of ovary ecdysteroidogenic hormone (OEH) and insulin-like peptide 3 (ILP3). This induces the ovaries to produce ecdysteroid hormone (ECD), which then drives egg maturation. In many immature insects, prothoracicotropic hormone (PTTH) stimulates the prothoracic glands to produce ECD that directs molting and metamorphosis. The receptors for OEH, ILP3 and PTTH are different receptor tyrosine kinases with OEH and ILP3 signaling converging downstream in the insulin pathway and PTTH activating the mitogen-activated protein kinase pathway. Calcium (Ca2+) flux and cAMP have also been implicated in PTTH signaling, but the role of Ca2+ in OEH, ILP3, and cAMP signaling in ovaries is unknown. Here, we assessed whether Ca2+ flux affects OEH, ILP3, and cAMP activity in A. aegypti ovaries and also asked whether PTTH stimulated ovaries to produce ECD. Results indicated that Ca2+ flux enhanced but was not essential for OEH or ILP3 activity, whereas cAMP signaling was dependent on Ca2+ flux. Recombinant PTTH from Bombyx mori fully activated ECD production by B. mori PTGs, but exhibited no activity toward A. aegypti ovaries. Recombinant PTTH from A. aegypti also failed to stimulate either B. mori PTGs or A. aegypti ovaries to produce ECD. We discuss the implications of these results in the context of mosquito reproduction and ECD biosynthesis by insects generally.
      Graphical abstract image

      PubDate: 2016-01-08T08:18:15Z
       
  • A Jonah-like chymotrypsin from the therapeutic maggot Lucilia sericata
           plays a role in wound debridement and coagulation
    • Abstract: Publication date: Available online 7 January 2016
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Anne-Kathrin Pöppel, Mareike Kahl, Andre Baumann, Jochen Wiesner, Anke Gökçen, Annika Beckert, Klaus T. Preissner, Andreas Vilcinskas, Zdeněk Franta
      Lucilia sericata larvae are used in maggot debridement therapy, a traditional wound healing approach that has recently been approved for the treatment of chronic wounds. Maggot excretion products (MEP) contain many different proteases that promote disinfection, debridement and the acceleration of wound healing, e.g. by activating the host contact phase/intrinsic pathway of coagulation. In order to characterise relevant procoagulant proteases, we analysed MEP and identified a chymotrypsin-like serine protease with similarities to Jonah proteases from Drosophila melanogaster and a chymotrypsin from Lucilia cuprina. A recombinant form of the L. sericata Jonah chymotrypsin was produced in Escherichia coli. The activated enzyme (Jonahm) had a pH optimum of 8.0 and a temperature optimum of 37°C, based on the cleavage of the chromogenic peptide s-7388 and casein. Jonahm reduced the clotting time of human plasma even in the absence of the endogenous protease kallikrein, factor XI or factor XII and digested the extracellular matrix proteins fibronectin, laminin and collagen IV, suggesting a potential mechanism of wound debridement. Based on these characteristics, the novel L. sericata chymotrypsin-like serine protease appears to be an ideal candidate for the development of topical drugs for wound healing applications.
      Graphical abstract image

      PubDate: 2016-01-08T08:18:15Z
       
  • Editorial Board
    • Abstract: Publication date: January 2016
      Source:Insect Biochemistry and Molecular Biology, Volume 68




      PubDate: 2016-01-03T07:48:11Z
       
  • Identification of the first insulin-like peptide in the disease vector
           Rhodnius prolixus: involvement in metabolic homeostasis of lipids and
           carbohydrates
    • Abstract: Publication date: Available online 29 December 2015
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Marina S. Defferrari, Ian Orchard, Angela B. Lange
      Insulin-like peptides (ILPs) are functional analogs of insulin and have been identified in many insect species. The insulin cell signaling pathway is a conserved regulator of metabolism, and in insects, as well as in other animals, can modulate physiological functions associated with the metabolism of lipids and carbohydrates. In the present study, we have identified the first ILP from the R. prolixus genome (termed Rhopr-ILP) and investigated its involvement in energy metabolism of unfed and recently fed fifth instars. We have cloned the cDNA sequence and analyzed the expression profile of the transcript, which is predominantly present in neurosecretory cells in the brain, similar to other insect ILPs. Using RNAi, we have reduced the expression of this peptide transcript by 90% and subsequently measured the carbohydrate and lipid levels in the hemolymph, fat body and leg muscles. Reduced levels of Rhopr-ILP transcript induced increased carbohydrate and lipid levels in the hemolymph and increased lipid content in the fat body, in unfed insects and recently fed insects. Also their fat bodies displayed enlarged lipid droplets within the cells. On the other hand, the carbohydrate content in the fat body and in the leg muscles of unfed insects were decreased when compared to control insects. Our results indicate that Rhopr-ILP is a modulator of lipid and carbohydrate metabolism, probably through signaling the presence of available energy and nutrients in the hemolymph.
      Graphical abstract image

      PubDate: 2015-12-30T07:35:32Z
       
  • NAP-1, Nucleosome assembly protein 1, a histone chaperone involved in
           Drosophila telomeres
    • Abstract: Publication date: Available online 30 December 2015
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Elisenda López-Panadès, Elena Casacuberta
      Telomere elongation is a function that all eukaryote cells must accomplish in order to guarantee, first, the stability of the end of the chromosomes and second, to protect the genetic information from the inevitable terminal erosion. The targeted transposition of the telomere transposons HeT-A, TART and TAHRE perform this function in Drosophila, while the telomerase mechanism elongates the telomeres in most eukaryotes. In order to integrate telomere maintenance together with cell cycle and metabolism, different components of the cell interact, regulate, and control the proteins involved in telomere elongation. Different partners of the telomerase mechanism have already been described, but in contrast, very few proteins have been related with assisting the telomere transposons of Drosophila. Here, we describe for the first time, the implication of NAP-1 (Nucleosome assembly protein 1), a histone chaperone that has been involved in nuclear transport, transcription regulation, and chromatin remodeling, in telomere biology. We find that Nap-1 and HeT-A Gag, one of the major components of the Drosophila telomeres, are part of the same protein complex. We also demonstrate that their close interaction is necessary to guarantee telomere stability in dividing cells. We further show that NAP-1 regulates the transcription of the HeT-A retrotransposon, pointing to a positive regulatory role of NAP-1 in telomere expression. All these results facilitate the understanding of the transposon telomere maintenance mechanism, as well as the integration of telomere biology with the rest of the cell metabolism.
      Graphical abstract image

      PubDate: 2015-12-30T07:35:32Z
       
  • Transcriptome analysis of the synganglion from the honey bee mite, Varroa
           destructor and RNAi knockdown of neural peptide targets
    • Abstract: Publication date: Available online 23 December 2015
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Ewan M. Campbell, Giles E. Budge, Max Watkins, Alan S. Bowman
      Varroa mites (Varroa destructor) and the viruses that they transmit are one of the major contributing factors to the global honey bee crisis. Gene products within the nervous system are the targets of all the insecticides currently used to control Varroa but there is a paucity of transcriptomic data available for Varroa neural tissues. A cDNA library from the synganglia (“brains”) of adult female Varroa was constructed and 600 ESTs sequenced and analysed revealing several current and potential druggable targets. Contigs coding for the deformed wing virus (DWV) variants Varroa destructor virus-1 (VDV-1) and the recombinant (VDV-1DVD) were present in the synganglion library. Negative-sense RNA-specific PCR indicated that VDV-1 replicates in the Varroa synganglion and all other tissues tested, but we could not detect DWV replicating in any Varroa tissue. Two neuropeptides were identified in the synganlion EST library: a B-type allatostatin and a member of the crustacean hyperglycaemic hormone (CHH) superfamily. Knockdown of the allatostatin or the CHH-like gene by double-stranded RNA-interference (dsRNAi) resulted in 85% and 55% mortality, respectively, of Varroa. Here, we present the first transcriptomic survey in Varroa and demonstrate that neural genes can be targeted by dsRNAi either for genetic validation of putative targets during drug discovery programmes or as a potential control measure in itself.
      Graphical abstract image

      PubDate: 2015-12-26T07:15:37Z
       
  • Expression of a sugar clade gustatory receptor, BmGr6, in the oral sensory
           organs, midgut, and central nervous system of larvae of the silkworm
           Bombyx mori
    • Abstract: Publication date: Available online 23 December 2015
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Dingze Mang, Min Shu, Haruka Endo, Yasutaka Yoshizawa, Shinji Nagata, Shingo Kikuta, Ryoichi Sato
      Insects taste nonvolatile chemicals through gustatory receptors (Grs) and make choices for feeding, mating, and ovipostion. To date, genome projects have identified 69 Gr genes in the silkworm, Bombyx mori; however, the expression sites of these Grs remain to be explored. In this study, we used reverse transcription (RT)-PCR to investigate expression of the B. mori Gr-6 (BmGr6) gene, a member of the putative sugar clade gene family in various tissues. BmGr6 is expressed in the midgut, central nervous system (CNS), and oral sensory organs. Moreover, immunohistochemistry using an anti-BmGr6 antiserum demonstrated that BmGr6 is expressed in cells by oral sensory organs, midgut and nervous system. Furthermore, double-immunohistochemistry indicated that BmGr6 is expressed in midgut enteroendocrine cells, also in CNS neurosecretory cells. In particular, a portion of BmGr6-expressing cells, in both midgut and CNS, secreting FMRFamide-related peptides (FaRPs). These results suggest that BmGr6 functions not only as a taste receptor, but also as a chemical sensor such as for the regulation of gut movement, physiological conditions, and feeding behavior of larvae.
      Graphical abstract image

      PubDate: 2015-12-26T07:15:37Z
       
  • Cyanide detoxification in an insect herbivore: Molecular identification of
           β-cyanoalanine synthases from Pieris rapae
    • Abstract: Publication date: Available online 20 December 2015
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Maike van Ohlen, Anna-Maria Herfurth, Henrike Kerbstadt, Ute Wittstock
      Cyanogenic compounds occur widely in the plant kingdom. Therefore, many herbivores are adapted to the presence of these compounds in their diet by either avoiding cyanide release or by efficient cyanide detoxification mechanisms. The mechanisms of adaptation are not fully understood. Larvae of Pieris rapae (Lepidoptera: Pieridae) are specialist herbivores on glucosinolate-containing plants. They are exposed to cyanide during metabolism of phenylacetonitrile, a product of benzylglucosinolate breakdown catalyzed by plant myrosinases and larval nitrile-specifier protein (NSP) in the gut. Cyanide is metabolized to β-cyanoalanine and thiocyanate in the larvae. Here, we demonstrate that larvae of P. rapae possess β-cyanoalanine activity in their gut. We have identified three gut-expressed cDNAs designated PrBSAS1-PrBSAS3 which encode proteins with similarity to β-substituted alanine synthases (BSAS). Characterization of recombinant PrBSAS1-PrBSAS3 shows that they possess β-cyanoalanine activity. In phylogenetic trees, PrBSAS1-PrBSAS3, the first characterized insect BSAS, group together with a characterized mite β-cyanoalanine synthase and bacterial enzymes indicating a similar evolutionary history.
      Graphical abstract image

      PubDate: 2015-12-22T06:54:53Z
       
  • In vivo study of Dicer-2-mediated immune response of the small interfering
           RNA pathway upon systemic infections of virulent and avirulent viruses in
           Bombus terrestris
    • Abstract: Publication date: Available online 19 December 2015
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Jinzhi Niu, Guy Smagghe, Dieter IM. De Coninck, Filip Van Nieuwerburgh, Dieter Deforce, Ivan Meeus
      Recent studies suggest a potent role of the small interfering RNA (siRNA) pathway in the control of bee viruses and its usefulness to tackle these viral diseases. However, the involvement of the siRNA pathway in the defense against different bee viruses is still poorly understood. Therefore, in this report, we comprehensively analyzed the response of the siRNA pathway in bumblebees of Bombus terrestris to systemic infections of the virulent Israeli acute paralysis virus (IAPV) and the avirulent slow bee paralysis virus (SBPV). Our results showed that IAPV and SBPV infections induced the expression of Dicer-2. IAPV infections also triggered the production of predominantly 22 nt-long virus-derived siRNAs (vsiRNAs). Intriguingly, these 22 nt-long vsiRNAs showed a high proportion of antigenomic IAPV sequences. Conversely, these predominantly 22 nt-long vsiRNAs of SBPV were not detected in SBPV infected bees. Furthermore, an “RNAi-of-RNAi” experiment on Dicer-2 did not result in altered genome copy numbers of IAPV (n = 17∼18) and also not of SBPV (n = 11∼12). Based on these results, we can speculate about the importance of the siRNA pathway in bumblebees for the antiviral response. During infection of IAPV, this pathway is probably recruited but it might be insufficient to control viral infection in our experimental setup. The host can control SBPV infection, but aside from the induction of Dicer-2 expression, no further evidence of the antiviral activity of the siRNA pathway was observed. This report may also enhance the current understanding of the siRNA pathway in the innate immunity of non-model insects upon different viral infections.
      Graphical abstract image

      PubDate: 2015-12-22T06:54:53Z
       
  • Mechanisms of nodule-specific melanization in the hemocoel of the
           silkworm, Bombyx mori
    • Abstract: Publication date: Available online 18 December 2015
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Min Shu, Dingze Mang, Gege Sun Fu, Shiho Tanaka, Haruka Endo, Shingo Kikuta, Ryoichi Sato
      In the insect immune system, nodules are known to be a product of the cellular response against microorganisms and may be a preferential target for melanization. However, the mechanism of nodule-preferential melanization remains to be explored. In this study, we identified several mechanisms of nodule-preferential melanization by analyzing congregation and the activation of several factors involved in the prophenoloxidase (proPO)-activating system in the silkworm, Bombyx mori. Microorganism-binding assays revealed that B. mori larval plasma have an effective invading microorganism-surveillance network consisting of at least six pattern-recognition receptors (PRRs). We also found that a hemolymph serine proteinase, BmHP14, can bind to S. cerevisiae. Pull-down assays showed that PRR C-type lectins form protein complexes with serine proteinase homologs, BmSPH1 and BmSPH2, which leads to the activated forms of BmSPH1 and BmSPH2 being gathered on microorganisms and trapped in nodules. Immunostaining analysis revealed that most factors in the proPO-activating system and some factors in the triggering system for antimicrobial peptide production exist in the granules of hemocytes which can gather in nodules. Western blot analysis showed that factors in the proPO-activating system are congregated in formed nodules by their concentration in plasma and aggregating hemocytes.
      Graphical abstract image

      PubDate: 2015-12-22T06:54:53Z
       
  • FOXO links wing form polyphenism and wound healing in the brown
           planthopper, Nilaparvata lugens
    • Abstract: Publication date: Available online 13 December 2015
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Xinda Lin, Yun Yao, Bo Wang, Mark D. Lavine, Laura Corley Lavine
      Polyphenisms such as wing dimorphisms and caste determination are important in allowing animals to adapt to changing environments. The brown planthopper Nilaparvata lugens, one of the most serious insect agricultural pests, includes two wing forms, the long wing form (macropterous) and the short wing form (brachypterous). Long wings are specialized for migration, while short wings are found in individuals specialized for reproduction. While studying wing form polyphenism in the brown planthopper, we excised single wing pads from 4th instar nymphs in order to preserve transcriptional records to correlate with adult wing form. Surprisingly, we found that excision of one wing pad from a pair of the forewings changed the wing morph of the other wing after development to the adult, resulting in the short wing morph. Further experiments showed that not only excision or slicing of the wing pad, but also needle punctures in the abdomen all caused a significant increase in the proportion of nymphs developing into short winged adults. Thus wounding appears to cause a shift to short wing development. We then tested the transcriptional expression in N. lugens of the transcription factor FOXO, which has been shown to help mediate both wing polyphenism in brown planthoppers and wound healing in mice, after excision of the wing pad. Both NlFOXO and its downstream target Nl4EBP increased significantly after wing pad excision. These results indicate that FOXO mediates both wing development and wound healing in N. lugens, which results in an interesting linkage of these two physiological processes.
      Graphical abstract image

      PubDate: 2015-12-14T06:30:21Z
       
  • Characterization and pharmacological analysis of two adipokinetic hormone
           receptor variants of the tsetse fly, Glossina morsitans morsitans
    • Abstract: Publication date: Available online 10 December 2015
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Jelle Caers, Tom Janssen, Liesbeth Van Rompay, Valérie Broeckx, Jan Van Den Abbeele, Gerd Gäde, Liliane Schoofs, Isabel Beets
      Adipokinetic hormones (AKH) are well known regulators of energy metabolism in insects. These neuropeptides are produced in the corpora cardiaca and perform their hormonal function by interacting with specific G protein-coupled receptors (GPCRs) at the cell membranes of target tissues, mainly the fat body. Here, we investigated the sequences, spatial and temporal distributions, and pharmacology of AKH neuropeptides and receptors in the tsetse fly, Glossina morsitans morsitans. The open reading frames of two splice variants of the Glomo-akh receptor (akhr) gene and of the AKH neuropeptide encoding genes, gmmhrth and gmmakh, were cloned. Both tsetse AKHR isoforms show strong sequence conservation when compared to other insect AKHRs. Glomo-AKH prepropeptides also have the typical architecture of AKH precursors. In an in vitro Ca2+ mobilization assay, Glomo-AKH neuropeptides activated each receptor isoform up to nanomolar concentrations. We identified structural features of tsetse AKH neuropeptides essential for receptor activation in vitro. Gene expression profiles suggest a function for AKH signaling in regulating Glossina energy metabolism, where AKH peptides are released from the corpora cardiaca and activate receptors mainly expressed in the fat body. This analysis of the ligand-receptor coupling, expression, and pharmacology of the two Glomo-AKHR variants facilitates further elucidation of the function of AKH in G. m. morsitans.
      Graphical abstract image

      PubDate: 2015-12-14T06:30:21Z
       
  • Targeted mutagenesis of an odorant receptor co-receptor using TALEN in
           Ostrinia furnacalis
    • Abstract: Publication date: Available online 12 December 2015
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Bin Yang, Takeshi Fujii, Yukio Ishikawa, Takashi Matsuo
      Genome editing using transcription activator-like effector nuclease (TALEN) has been applied for various model organisms but not yet for agricultural pest insects. In this study, TALEN-mediated mutagenesis of the gene encoding odorant receptor co-receptor (Orco) of an important agricultural pest Ostrinia furnacalis (OfurOrco) was carried out. Of the two pairs of TALEN constructs designed, one generated somatic and germline mutations at rates of 70.8% and 20.8%, respectively. Physiological and behavioral analyses using a gas chromatograph–electroantennographic detector system and a wind tunnel, respectively, revealed that antennal responses to sex pheromone components were decreased to trace levels, and behavioral responses were abolished in OfurOrco mutants. This study demonstrated that TALEN-mediated mutagenesis is applicable to pest insects, and these results will open the way for a better understanding of chemosensory systems in wild insects.
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      PubDate: 2015-12-14T06:30:21Z
       
  • Ecdysteroid promotes cell cycle progression in the Bombyx wing disc
           through activation of c-Myc
    • Abstract: Publication date: Available online 13 December 2015
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Minoru Moriyama, Kohji Osanai, Tomokazu Ohyoshi, Hua-Bing Wang, Masashi Iwanaga, Hideki Kawasaki
      Developmental switching from growth to metamorphosis in imaginal primordia is an essential process of adult body planning in holometabolous insects. Although it is disciplined by a sequential action of the ecdysteroid, molecular mechanisms linking to cell proliferation are poorly understood. In the present study, we investigated the expression control of cell cycle–related genes by the ecdysteroid using the wing disc of the final-instar larvae of the silkworm, Bombyx mori. We found that the expression level of c-myc was remarkably elevated in the post-feeding cell proliferation phase, which coincided with a small increase in ecdysteroid titer. An in vitro wing disc culture showed that supplementation of the moderate level of the ecdysteroid upregulated c-myc expression within an hour and subsequently increased the expression of cell cycle core regulators, including A-, B-, D-, and E-type cyclin genes, Cdc25 and E2F1. We demonstrated that c-myc upregulation by the ecdysteroid was not inhibited in the presence of a protein synthesis inhibitor, suggesting a possibility that the ecdysteroid directly stimulates c-myc expression. Finally, results from the administration of a c-Myc inhibitor demonstrated that c-Myc plays an essential role in 20E-inducible cell proliferation. These findings suggested a novel pathway for ecdysteroid-inducible cell proliferation in insects, and it is likely to be conserved between insects and mammals in terms of steroid hormone regulation.
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      PubDate: 2015-12-14T06:30:21Z
       
  • Protein kinase C modulates transcriptional activation by the juvenile
           hormone receptor methoprene-tolerant
    • Abstract: Publication date: Available online 13 December 2015
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Reyhaneh Ojani, Pengcheng Liu, Xiaonan Fu, Jinsong Zhu
      Juvenile hormone (JH) controls many biological events in insects by triggering dramatic changes in gene expression in target cells. The Methoprene-tolerant (MET) protein, an intracellular JH receptor, acts as a transcriptional regulator and binds to the promoters of tissue- and stage-specific JH target genes when JH is present. Our recent study has demonstrated that the transcriptional activation by MET is modulated by a membrane-initiated JH signaling pathway, involving phospholipase C (PLC) and calcium/calmodulin-dependent protein kinase II (CaMKII). Here we report that protein kinase C (PKC) is another essential intermediate of this pathway. PKC was activated by JH and this action was PLC-dependent. Inhibition of the PKC activity substantially weakened the JH-induced gene expression in mosquito cells. RNAi experiments indicated that several PKC isoforms were involved in the JH action during the post-emergence development of adult female mosquitoes. JH treatment considerably increased the binding of MET to the promoters of JH response genes in cultured mosquito abdomens that were collected from newly emerged female adults. The JH-induced DNA binding of MET was hindered when the abdomens were treated with a PKC inhibitor and JH. Therefore, the results suggest that PKC modulates the transactivation activity of MET by enhancing the binding of MET to JH response elements in the JH target genes. This mechanism may allow for variable and stage- and tissue-specific genomic responses to JH.
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      PubDate: 2015-12-14T06:30:21Z
       
  • Organ-specific transcriptome response of the small brown planthopper
           toward rice stripe virus
    • Abstract: Publication date: Available online 8 December 2015
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Wan Zhao, Lixia Lu, Pengcheng Yang, Na Cui, Le Kang, Feng Cui
      Rice stripe virus (RSV) causes rice stripe disease and is transmitted by the small brown planthopper (Laodelphax striatellus, SBPH) in a persistent, circulative, and propagative manner. The alimentary canal and salivary gland of SBPH play important roles in viral replication and transmission. However, little is known about the underlying molecular functions of these two organs in the interaction between RSV and SBPH. In this study, organ-specific transcriptomes of the alimentary canal and salivary gland were analyzed in viruliferous and naïve SBPH. The number of differentially expressed unigenes in the alimentary canal was considerably greater than that in the salivary gland after RSV infection, and only 23 unigenes were co-regulated in the two organs. In the alimentary canal, genes involved in lysosome, digestion and detoxification were activated upon RSV infection, whereas the genes related to DNA replication and repair were suppressed. RSV activated RNA transport and repressed the MAPK, mTOR, Wnt, and TGF-beta signaling pathways in the salivary gland. The overall immune reaction toward RSV was much stronger in the salivary gland than in the alimentary canal. RSV activated the pattern recognition molecules and Toll pathway in the salivary gland but inhibited these two reactions in the alimentary canal. The responses from reactive oxygen and the immune-responsive effectors were stronger in the salivary gland than in the alimentary canal after RSV infection. These findings provide clues on the roles of the two organs in confronting RSV infection and aid in the understanding of the interaction between RSV and SBPHs.
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      PubDate: 2015-12-09T06:09:45Z
       
  • Insect midgut α-mannosidases from family 38 and 47 with emphasis on
           those of Tenebrio molitor
    • Abstract: Publication date: December 2015
      Source:Insect Biochemistry and Molecular Biology, Volume 67
      Author(s): Nathalia R. Moreira, Christiane Cardoso, Alberto F. Ribeiro, Clelia Ferreira, Walter R. Terra
      α-Mannosidases are enzymes which remove non-reducing terminal residues from glycoconjugates. Data on both GH47 and GH38 (Golgi and lysosomal) enzymes are available. Data on insect midgut α-mannosidases acting in digestion are preliminary and do not include enzyme sequences. Tenebrio molitor midgut α-mannosidases were separated by chromatography into two activity peaks: a major (Man1) and a minor (Man2). An antibody generated against a synthetic peptide corresponding to a sequence of α-mannosidase fragment recognizes Man2 but not Man1. That fragment was later found to correspond to TmMan2 (GenBank access KP892646), showing that the cDNA coding for Man2 is actually TmMan2. TmMan2 codes for a mature α-mannosidase with 107.5 kDa. Purified Man2 originates after SDS-PAGE one band of about 72 kDa and another of 51 kDa, which sums 123 kDa, in agreement with gel filtration (123 kDa) data. These results suggest that Man2 is processed into peptides that remain noncovalently linked within the functional enzyme. The physical and kinetical properties of purified Man1 and Man2 are similar. They have a molecular mass of 123 kDa (gel filtration), pH optimum (5.6) and response to inhibitors like swainsonine (Man1 Ki, 68 nM; Man2 Ki, 63 nM) and deoxymannojirimycin (Man1 Ki, 0.12 mM; Man2 Ki, 0.15 mM). Their substrate specificities are a little different as Man2 hydrolyzes α-1,3 and α-1,6 bonds better than α-1,2, whereas the contrary is true for Man1. Thus, they pertain to Class II (GH38 α-mannosidases), that are catabolic α-mannosidases similar to lysosomal α-mannosidase. However, Man2, in contrast to true lysosomal α-mannosidase, is secreted (immunocytolocalization data) into the midgut contents. There, Man2 may participate in digestion of fungal cell walls, known to have α-mannosides in their outermost layer. The amount of family 38 α-mannosidase sequences found in the transcriptome (454 pyrosequencing) of the midgut of 9 insects pertaining to 5 orders is perhaps related to the diet of these organisms, as suggested by a large number of lysosomal α-mannosidase in the T. molitor midgut.
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      PubDate: 2015-12-04T05:52:19Z
       
  • Development of neuropeptide analogs capable of traversing the integument:
           A case study using diapause hormone analogs in Helicoverpa zea
    • Abstract: Publication date: December 2015
      Source:Insect Biochemistry and Molecular Biology, Volume 67
      Author(s): Qirui Zhang, Ronald J. Nachman, Krzysztof Kaczmarek, Krzysztof Kierus, Janusz Zabrocki, David L. Denlinger
      Diapause hormone and its analogs terminate pupal diapause in Helicoverpa zea when injected, but if such agents are to be used as effective diapause disruptors it will be essential to develop simple techniques for administering active compounds that can exert their effect by penetrating the insect epidermis. In the current study, we used two molecules previously shown to have high diapause-terminating activity as lead molecules to rationally design and synthesize new amphiphilic compounds with modified hydrophobic components. An assay for diapause termination identified 13 active compounds with EC50's ranging from 0.9 to 46.0 pmol per pupa. Three compounds, Decyl-1963, Dodecyl-1967, and Heptyl-1965, selected from the 13 compounds most active in breaking diapause following injection, also successfully prevented newly-formed pupae from entering diapause when applied topically. These compounds feature straight-chain, aliphatic hydrocarbons from 7 to 12 carbons in length; DH analogs with either a short-chain length of 4 or an aromatic phenethyl group failed to act topically. Compared to a high diapause incidence of 80–90% in controls, diapause incidence in pupae receiving a 10 nmole topical application of Decyl-1963, Dodecyl-1967, or Heptyl-1965 dropped to 30–45%. Decyl-1963 and Dodecyl-1967 also remained effective when topically applied at the 1 nmole level. These results suggest the feasibility of developing DH agonists that can be applied topically and suggest the identity of new lead molecules for development of additional topically-active DH analogs. The ability to penetrate the insect epidermis and/or midgut lining is critical if such agents are to be considered for future use as pest management tools.
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      PubDate: 2015-12-04T05:52:19Z
       
  • Localization and role of inward rectifier K+ channels in Malpighian
           tubules of the yellow fever mosquito Aedes aegypti
    • Abstract: Publication date: December 2015
      Source:Insect Biochemistry and Molecular Biology, Volume 67
      Author(s): Peter M. Piermarini, Sonja M. Dunemann, Matthew F. Rouhier, Travis L. Calkins, Rene Raphemot, Jerod S. Denton, Rebecca M. Hine, Klaus W. Beyenbach
      Malpighian tubules of adult female yellow fever mosquitoes Aedes aegypti express three inward rectifier K+ (Kir) channel subunits: AeKir1, AeKir2B and AeKir3. Here we 1) elucidate the cellular and membrane localization of these three channels in the Malpighian tubules, and 2) characterize the effects of small molecule inhibitors of AeKir1 and AeKir2B channels (VU compounds) on the transepithelial secretion of fluid and electrolytes and the electrophysiology of isolated Malpighian tubules. Using subunit-specific antibodies, we found that AeKir1 and AeKir2B localize exclusively to the basolateral membranes of stellate cells and principal cells, respectively; AeKir3 localizes within intracellular compartments of both principal and stellate cells. In isolated tubules bathed in a Ringer solution containing 34 mM K+, the peritubular application of VU590 (10 μM), a selective inhibitor of AeKir1, inhibited transepithelial fluid secretion 120 min later. The inhibition brings rates of transepithelial KCl and fluid secretion to 54% of the control without a change in transepithelial NaCl secretion. VU590 had no effect on the basolateral membrane voltage (Vbl) of principal cells, but it significantly reduced the cell input conductance (gin) to values 63% of the control within ∼90 min. In contrast, the peritubular application of VU625 (10 μM), an inhibitor of both AeKir1 and AeKir2B, started to inhibit transepithelial fluid secretion as early as 60 min later. At 120 min after treatment, VU625 was more efficacious than VU590, inhibiting transepithelial KCl and fluid secretion to ∼35% of the control without a change in transepithelial NaCl secretion. Moreover, VU625 caused the Vbl and gin of principal cells to respectively drop to values 62% and 56% of the control values within only ∼30 min. Comparing the effects of VU590 with those of VU625 allowed us to estimate that AeKir1 and AeKir2B respectively contribute to 46% and 20% of the transepithelial K+ secretion when the tubules are bathed in a Ringer solution containing 34 mM K+. Thus, we uncover an important role of AeKir1 and stellate cells in transepithelial K+ transport under conditions of peritubular K+ challenge. The physiological role of AeKir3 in intracellular membranes of both stellate and principal cells remains to be determined.
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      PubDate: 2015-12-04T05:52:19Z
       
  • A comprehensive transcriptomic view of renal function in the malaria
           vector, Anopheles gambiae
    • Abstract: Publication date: December 2015
      Source:Insect Biochemistry and Molecular Biology, Volume 67
      Author(s): Gayle Overend, Pablo Cabrero, Kenneth A. Halberg, Lisa C. Ranford-Cartwright, Debra J. Woods, Shireen A. Davies, Julian A.T. Dow
      Renal function is essential to maintain homeostasis. This is particularly significant for insects that undergo complete metamorphosis; larval mosquitoes must survive a freshwater habitat whereas adults are terrestrial, and mature females must maintain ion and fluid homeostasis after blood feeding. To investigate the physiological adaptations required for successful development to adulthood, we studied the Malpighian tubule transcriptome of Anopheles gambiae using Affymetrix arrays. We assessed transcription under several conditions; as third instar larvae, as adult males fed on sugar, as adult females fed on sugar, and adult females after a blood meal. In addition to providing the most detailed transcriptomic data to date on the Anopheles Malpighian tubules, the data provide unique information on the renal adaptations required for the switch from freshwater to terrestrial habitats, on gender differences, and on the contrast between nectar-feeding and haematophagy. We found clear differences associated with ontogenetic change in lifestyle, gender and diet, particularly in the neuropeptide receptors that control fluid secretion, and the water and ion transporters that impact volume and composition. These data were also combined with transcriptomics from the Drosophila melanogaster tubule, allowing meta-analysis of the genes which underpin tubule function across Diptera. To further investigate renal conservation across species we selected four D. melanogaster genes with orthologues highly enriched in the Anopheles tubules, and generated RNAi knockdown flies. Three of these genes proved essential, showing conservation of critical functions across 150 million years of phylogenetic separation. This extensive data-set is available as an online resource, MozTubules.org, and could potentially be mined for novel insecticide targets that can impact this critical organ in this pest species.
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      PubDate: 2015-12-04T05:52:19Z
       
  • A novel role of Drosophila cytochrome P450-4e3 in permethrin insecticide
           tolerance
    • Abstract: Publication date: December 2015
      Source:Insect Biochemistry and Molecular Biology, Volume 67
      Author(s): Selim Terhzaz, Pablo Cabrero, Robert A. Brinzer, Kenneth A. Halberg, Julian A.T. Dow, Shireen-A. Davies
      The exposure of insects to xenobiotics, such as insecticides, triggers a complex defence response necessary for survival. This response includes the induction of genes that encode key Cytochrome P450 monooxygenase detoxification enzymes. Drosophila melanogaster Malpighian (renal) tubules are critical organs in the detoxification and elimination of these foreign compounds, so the tubule response induced by dietary exposure to the insecticide permethrin was examined. We found that expression of the gene encoding Cytochrome P450-4e3 (Cyp4e3) is significantly up-regulated by Drosophila fed on permethrin and that manipulation of Cyp4e3 levels, specifically in the principal cells of the Malpighian tubules, impacts significantly on the survival of permethrin-fed flies. Both dietary exposure to permethrin and Cyp4e3 knockdown cause a significant elevation of oxidative stress-associated markers in the tubules, including H2O2 and lipid peroxidation byproduct, HNE (4-hydroxynonenal). Thus, Cyp4e3 may play an important role in regulating H2O2 levels in the endoplasmic reticulum (ER) where it resides, and its absence triggers a JAK/STAT and NF-κB-mediated stress response, similar to that observed in cells under ER stress. This work increases our understanding of the molecular mechanisms of insecticide detoxification and provides further evidence of the oxidative stress responses induced by permethrin metabolism.
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      PubDate: 2015-12-04T05:52:19Z
       
  • From mouth to anus: Functional and structural relevance of enteric neurons
           in the Drosophila melanogaster gut
    • Abstract: Publication date: December 2015
      Source:Insect Biochemistry and Molecular Biology, Volume 67
      Author(s): Takayuki Kuraishi, Hiroyuki Kenmoku, Shoichiro Kurata
      The intestinal tract is the main organ involved in host nutritional homeostasis. Intestinal function in both vertebrates and invertebrates is partly controlled by enteric neurons that innervate the gut. Though anatomical and functional aspects of enteric neurons are relatively less characterized in Drosophila than in large insects, analyses of the role of the enteric neurons in flies have remarkably progressed in the last few years. In this review, we first provide a summary of the structure and function of the Drosophila intestine. We then discuss recent studies of the structure and function of enteric neurons in Drosophila melanogaster.
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      PubDate: 2015-12-04T05:52:19Z
       
  • G protein coupled receptors as targets for next generation pesticides
    • Abstract: Publication date: December 2015
      Source:Insect Biochemistry and Molecular Biology, Volume 67
      Author(s): Neil Audsley, Rachel E. Down
      There is an on-going need for the discovery and development of new pesticides due to the loss of existing products through the continuing development of resistance, the desire for products with more favourable environmental and toxicological profiles and the need to implement the principles of integrated pest management. Insect G protein coupled receptors (GPCRs) have important roles in modulating biology, physiology and behaviour, including reproduction, osmoregulation, growth and development. Modifying normal receptor function by blocking or over stimulating its actions may either result in the death of a pest or disrupt its normal fitness or reproductive capacity to reduce pest populations. Hence GPCRs offer potential targets for the development of next generation pesticides providing opportunities to discover new chemistries for invertebrate pest control. Such receptors are important targets for pharmaceutical drugs, but are under-exploited by the agro-chemical industry. The octopamine receptor agonists are the only pesticides with a recognized mode of action, as described in the classification scheme developed by the Insecticide Resistance Action Committee, that act via a GPCR. The availability of sequenced insect genomes has facilitated the characterization of insect GPCRs, but the development and utilization of screening assays to identify lead compounds has been slow. Various studies using knock-down technologies or applying the native ligands and/or neuropeptide analogues to pest insects in vivo, have however demonstrated that modifying normal receptor function can have an insecticidal effect. This review presents examples of potential insect neuropeptide receptors that are potential targets for lead compound development, using case studies from three representative pest species, Tribolium castaneum, Acyrthosiphon pisum, and Drosophila suzukii. Functional analysis studies on T. castaneum suggest that GPCRs involved in growth and development (eclosion hormone, ecdysis triggering hormone and crustacean cardioacceleratory peptide receptors) as well as the dopamine-2 like, latrophilin-like, starry night, frizzled-like, methuselah-like and the smoothened receptors may be suitable pesticide targets. From in vivo studies using native ligands and peptide analogues, receptors which appear to have a role in the regulation of feeding in the pea aphid, such as the PISCF-allatostatin and the various “kinin” receptors, are also potential targets. In Drosophila melanogaster various neuropeptides and their signalling pathways have been studied extensively. This may provide insights into potential pesticide targets that could be exploited in D. suzukii. Examples include the sex peptide receptor, which is involved in reproduction and host seeking behaviours, and those responsible for osmoregulation such as the diuretic hormone receptors. However the neuropeptides and their receptors in insects are often poorly characterized, especially in pest species. Although data from closely related species may be transferable (e.g. D. melanogaster to D. suzukii), peptides and receptors may have different roles in different insects, and hence a target in one insect may not be appropriate in another. Hence fundamental knowledge of the roles and functions of receptors is vital for development to proceed.
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      PubDate: 2015-12-04T05:52:19Z
       
  • The multi-tasking gut epithelium of insects
    • Abstract: Publication date: December 2015
      Source:Insect Biochemistry and Molecular Biology, Volume 67
      Author(s): Jia-Hsin Huang, Xiangfeng Jing, Angela E. Douglas
      The insect gut epithelium plays a vital role in multiple processes, including nutrition, immunity and osmoregulation. Recent research is revealing the molecular and biochemical basis of these functions. For example, the pattern of nutrient acquisition by the gut epithelium is integrated into the overall regulation of nutrient allocation, as illustrated by evidence for systemic controls over expression of key genes coding digestive enzymes and transporters in carbohydrate acquisition; and the abundance and diversity of microorganisms in the gut lumen is regulated by multiple molecular properties of the gut epithelial cells, including the synthesis of enzymes that produce reactive oxygen species and anti-microbial peptides. These traits are underpinned by the function of the gut epithelium as a selective barrier which mediates the controlled movement of water, ions, metabolites and macromolecules between the gut lumen and insect tissues. Breakdown of the gut epithelial barrier has been implicated in muscle paralysis of insects at low temperatures (chill coma) and in aging. The key challenge for future research is to understand how the multiple functions of the insect gut epithelium are integrated by signaling interactions among epithelial cells, the gut microbiota and other insect organs.
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      PubDate: 2015-12-04T05:52:19Z
       
  • Editorial Board
    • Abstract: Publication date: December 2015
      Source:Insect Biochemistry and Molecular Biology, Volume 67




      PubDate: 2015-12-04T05:52:19Z
       
  • All for one and one for all: Regionalization of the Drosophila intestine
    • Abstract: Publication date: December 2015
      Source:Insect Biochemistry and Molecular Biology, Volume 67
      Author(s): Nicolas Buchon, Dani Osman
      Physiological responses are the ultimate outcomes of the functional interactions and proper organization of the different cell types that make up an organ. The digestive tract represents a good example where such structure/function correlation is manifested. To date, the molecular mechanisms that establish and/or maintain gut segmentation and functional specialization remain poorly understood. Recently, the use of model systems such as Drosophila has enriched our knowledge about the gut organization and physiology. Here, we review recent studies deciphering the morphological and functional properties of the Drosophila adult midgut compartments. Intestinal compartments are established through the differentiation of regionalized stem cell populations in concert with the joint activity of patterned transcription factors and locally produced morphogens. The maintenance of a compartmentalized gut structure is vital to the organism, allowing sequentially the ingestion and digestion of food, absorption of nutrients, and excretion of waste products in addition to the compartmentalization of immune and homeostatic functions. Further characterization of the gene regulatory networks underlying gut compartmentalization will pave the way for a better understanding of gastrointestinal function in insects and mammals, in both health and disease conditions.
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      PubDate: 2015-12-04T05:52:19Z
       
  • Intestinal stem cell proliferation and epithelial homeostasis in the adult
           Drosophila midgut
    • Abstract: Publication date: December 2015
      Source:Insect Biochemistry and Molecular Biology, Volume 67
      Author(s): Máté Nászai, Lynsey R. Carroll, Julia B. Cordero
      Adult tissue homeostasis requires a tight balance between the removal of old or damaged cells and the production of new ones. Such processes are usually driven by dedicated stem cells that reside within specific tissue locations or niches. The intestinal epithelium has a remarkable regenerative capacity, which has made it a prime paradigm for the study of stem cell-driven tissue self-renewal. The discovery of the presence of stem cells in the adult midgut of the fruit fly Drosophila melanogaster has significantly impacted our understanding of the role of stem cells in intestinal homeostasis. Here we will review the current knowledge of the main mechanisms involved in the regulation of tissue homeostasis in the adult Drosophila midgut, with a focus on the role of stem cells in this process. We will also discuss processes involving acute or chronic disruption of normal intestinal homeostasis such as damage-induced regeneration and ageing.
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      PubDate: 2015-12-04T05:52:19Z
       
  • Stink bug predator kills prey with salivary non-proteinaceous compounds
    • Abstract: Publication date: Available online 2 December 2015
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Luis Carlos Martínez, Maria do Carmo Queiroz Fialho, Luiz Claudio Almeida Barbosa, Leandro Licursi Oliveira, José Cola Zanuncio, José Eduardo Serrão
      Podisus nigrispinus Dallas (Hemiptera: Pentatomidae) is a predator insect with potential applications in biological control because both nymphs and adults have been shown to prey on other insect pests by injection of toxic salivary gland contents. This study identified non-proteinaceous compounds with insecticidal activity from the saliva of P. nigrispinus in Anticarsia gemmatalis. In particular, the ether extract from P. nigrispinus saliva led to mortality in A. gemmatalis larvae, with a LC50 = 2.04 μL and LC90 = 3.27 μL. N,N-dimethylaniline and 1,2,5-trithiepane fractions were identified as non-proteinaceous extract components. N,N-dimethylaniline had a LC50 = 136.1 nL and LC90 = 413.8 nL, suggesting that it could be responsible for toxicity in P. nigrispinus saliva.
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      PubDate: 2015-12-04T05:52:19Z
       
  • Editorial Board
    • Abstract: Publication date: November 2015
      Source:Insect Biochemistry and Molecular Biology, Volume 66




      PubDate: 2015-11-29T22:41:53Z
       
  • Nutrient-dependent control of short Neuropeptide F transcript levels via
           components of the insulin/IGF signaling pathway in the desert locust,
           Schistocerca gregaria
    • Abstract: Publication date: Available online 27 November 2015
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Senne Dillen, Ziwei Chen, Jozef Vanden Broeck
      Peptides of the short neuropeptide F (sNPF) family modulate feeding behavior in a wide variety of insect species, including the desert locust, Schistocerca gregaria. Likewise, the nutritional state of the animal can strongly affect sNPF expression. Although several studies have been published describing these nutrient-dependent effects, it remains largely unclear how they are achieved. In this study, we describe a series of in vivo experiments which indicate that it is not the act of feeding in se, but rather the consequent availability of nutrients in the insect’s hemolymph that gives rise to the postprandial modulation of sNPF expression. Furthermore, by performing a series of RNAi-mediated knockdown experiments, we were able to show that components of the evolutionary conserved insulin/insulin-related growth factor (IGF) signaling pathway form a functional link between nutrient levels and sNPF transcript levels.
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      PubDate: 2015-11-29T22:41:53Z
       
  • Glutathione S-transferase SlGSTE1 in Spodoptera litura may be associated
           with feeding adaptation of host plants
    • Abstract: Publication date: Available online 26 November 2015
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Xiaopeng Zou, Zhibin Xu, Haiwang Zou, Jisheng Liu, Shuna Chen, Qili Feng, Sichun Zheng
      Spodoptera litura is polyphagous pest insect and feeds on plants of more than 90 families. In this study the role of glutathione S-transferase epilson 1 (slgste1) in Spodoptera litura in detoxification was examined. This gene was up-regulated in the midgut of S. litura at the transcriptional and protein levels when the insect fed on Brassica juncea or diet containing phytochemicals such as indole-3-carbinol and allyl-isothiocyanate that are metabolic products of sinigrin and glucobrassicin in B. juncea. The SlGSTE1 could catalyze the conjugation of reduced glutathione and indole-3-carbinol and allyl-isothiocyanate, as well as xanthotoxin, which is a furanocoumarin, under in vitro condition. When the expression of Slgste1 in the larvae was suppressed with RNAi, the larval growth and feeding rate were decreased. Furthermore, the up-regulated expression of the SlGSTE1 protein in the midgut of larvae that fed on different host plants was detected by 2-DE and ESI/MS analysis. The feeding adaptation from the most to the least of the larvae for the various host plants was Brassica alboglabra, Brassica linn. Pekinensis, Cucumis sativus, Ipomoea batatas, Arachis hypogaea and Capsicum frutescens. All the results together suggest that Slgste1 is a critical detoxifying enzyme that is induced by phytochmicals in the host plants and, inter alia, may be related to host plant adaptation of S. litura.
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      PubDate: 2015-11-29T22:41:53Z
       
  • The fucomic potential of mosquitoes: Fucosylated n-glycan epitopes and
           their cognate fucosyltransferases
    • Abstract: Publication date: Available online 23 November 2015
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Simone Kurz, Jonas G. King, Rhoel R. Dinglasan, Katharina Paschinger, Iain B.H. Wilson
      Fucoconjugates are key mediators of protein-glycan interactions in prokaryotes and eukaryotes. As examples, N-glycans modified with the non-mammalian core α1,3-linked fucose have been detected in various organisms ranging from plants to insects and are immunogenic in mammals. The rabbit polyclonal antibody raised against plant horseradish peroxidase (anti-HRP) is able to recognize the α1,3-linked fucose epitope and is also known to specifically stain neural tissues in the fruit fly Drosophila melanogaster. In this study, we have detected and localized the anti-HRP cross-reactivity in another insect species, the malaria mosquito vector Anopheles gambiae. We were able to identify and structurally elucidate fucosylated N-glycans including core mono- and difucosylated structures (responsible for anti-HRP cross reactivity) as well as a Lewis-type antennal modification on mosquito anionic N-glycans by applying enzymatic and chemical treatments. The three mosquito fucosyltransferase open reading frames (FucT6, FucTA and FucTC) required for the in vivo biosynthesis of the fucosylated N-glycan epitopes were identified in the Anopheles gambiae genome, cloned and recombinantly expressed in Pichia pastoris. Using a robust MALDI-TOF MS approach, we characterised the activity of the three recombinant fucosyltransferases in vitro and demonstrate that they share similar enzymatic properties as compared to their homologues from D. melanogaster and Apis mellifera. Thus, not only do we confirm the neural reactivity of anti-HRP in a mosquito species, but also demonstrate enzymatic activity for all its α1,3- and α1,6-fucosyltransferase homologues, whose specificity matches the results of glycomic analyses.
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      PubDate: 2015-11-26T14:54:42Z
       
  • Comparative transcriptome analysis of Bombyx mori spinnerets and
           Filippi’s glands suggests their role in silk fiber formation
    • Abstract: Publication date: Available online 25 November 2015
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Xin Wang, Yi Li, Li Peng, Huifang Chen, Qingyou Xia, Ping Zhao
      The spinneret is located at the end of silk glands in the silkworm, Bombyx mori. The Filippi’s gland (FG), which communicates with the silk gland, is considered an accessory to the latter. Although these two organs have been known for centuries, only their morphology has been studied. Their gene expression profiles and physiological roles are still unknown. Aided by next-generation sequencing, we profiled more than 11000 transcripts from the spinneret and FG of silkworm larvae on day 3 of the fifth instar (L5D3) and wandering stage (W1) in this study. A total of 59 ion-transporting protein genes and 106 cuticle protein genes were identified in the spinneret. To analyze the dynamic changes in the expression of spinneret genes, differential expression analysis was performed, and 1452 differentially expressed genes (DEGs) were identified in spinneret tissue harvested on L5D3 and W1 of the silkworm larvae. Gene Ontology (GO) enrichment and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment of the DEGs revealed that the spinneret had active ion-transporting, chitin binding, and energy metabolism processes at W1. Based on these data, we hypothesized that the role of the spinneret is to provide a favorable physiological environment for the silk fiber formation. Furthermore, differential expression analysis and GO enrichment of the DEGs in the FG suggested a possible role of this gland in transporting small solutes such as ions, sugars and amino acids to the silk gland. Our findings pave a way for further functional explanation of the spinneret and FG.
      Graphical abstract image

      PubDate: 2015-11-26T14:54:42Z
       
  • Two Leptinotarsa uridine diphosphate N-acetylglucosamine
           pyrophosphorylases are specialized for chitin synthesis in larval
           epidermal cuticle and midgut peritrophic matrix
    • Abstract: Publication date: Available online 22 November 2015
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Ji-Feng Shi, Jia Fu, Li-Li Mu, Wen-Chao Guo, Guo-Qing Li
      Uridine diphosphate-N-acetylglucosamine-pyrophosphorylase (UAP) is involved in the biosynthesis of chitin, an essential component of the epidermal cuticle and midgut peritrophic matrix (PM) in insects. In the present paper, two putative LdUAP genes were cloned in Leptinotarsa decemlineata. In vivo bioassay revealed that 20-hydroxyecdysone (20E) and an ecdysteroid agonist halofenozide activated the expression of the two LdUAPs, whereas a decrease in 20E by RNA interference (RNAi) of an ecdysteroidogenesis gene LdSHD and a 20E signaling gene LdFTZ-F1 repressed the expression. Juvenile hormone (JH), a JH analog pyriproxyfen and an increase in JH by RNAi of an allatostatin gene LdAS-C downregulated LdUAP1 but upregulated LdUAP2, whereas a decrease in JH by silencing of a JH biosynthesis gene LdJHAMT had converse effects. Thus, expression of LdUAPs responded to both 20E and JH. Moreover, knockdown of LdUAP1 reduced chitin contents in whole larvae and integument samples, thinned tracheal taenidia, impaired larval-larval molt, larval-pupal ecdysis and adult emergence. In contrast, silencing of LdUAP2 significantly reduced foliage consumption, decreased chitin content in midgut samples, damaged PM, and retarded larval growth. The resulting larvae had lighter fresh weights, smaller body sizes and depleted fat body. As a result, the development was arrested. Combined knockdown of LdUAP1 and LdUAP2 caused an additive negative effect. Our data suggest that LdUAP1 and LdUAP2 have specialized functions in biosynthesizing chitin in the epidermal cuticle and PM respectively in L. decemlineata.
      Graphical abstract image

      PubDate: 2015-11-22T14:48:09Z
       
  • Crystal structure of vespid phospholipase A1 reveals insights into the
           mechanism for cause of membrane dysfunction
    • Abstract: Publication date: Available online 19 November 2015
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Ming-Hon Hou, Chien-Ying Chuang, Tzu-Ping Ko, Nien-Jen Hu, Chia-Cheng Chou, Yan-Ping Shih, Chewn-Lang Ho, Andrew H.-J. Wang
      Vespid phospholipase A1 (vPLA1) from the black-bellied hornet (Vespa basalis) catalyzes the hydrolysis of emulsified phospholipids and shows potent hemolytic activity that is responsible for its lethal effect. To investigate the mechanism of vPLA1 towards its function such as hemolysis, emulsification, we isolated vPLA1 from V. basalis venom and determined its crystal structure at 2.5 Å resolution and vPLA1 belongs to the α/β hydrolase fold family. It contains a tightly packed β-sheet surrounded by ten α-helices and a Gly-X-Ser-X-Gly motif, characteristic of a serine hydrolyase active site. A bound phospholipid was modeled into the active site adjacent to the catalytic Ser-His-Asp triad shows that Gln95 is located at hydrogen-bonding distance from the substrate's phosphate group. Moreover, a hydrophobic surface comprised by the side chains of Phe53, Phe62, Met91, Tyr99, Leu197, Ala167 and Pro169 may serve as the acyl chain-binding site. vPLA1 shows global similarity to the N-terminal domain of human pancreatic lipase (HPL), but with some local differences. The lid domain and the β9 loop are responsible for substrate selectivity are shorter in vPLA1 than in HPL. Thus, solvent-exposed hydrophilic residues can easily accommodate the polar head groups of phospholipids, thereby accounting for the high activity level of vPLA1. Our result provides a potential explanation for the ability of vPLA1 to hydrolyze phospholipids of cell membrane.
      Graphical abstract image

      PubDate: 2015-11-22T14:48:09Z
       
  • EWGWS insert in Plasmodium falciparum ookinete surface enolase is involved
           in binding of PWWP containing peptides: Implications to mosquito midgut
           invasion by the parasite
    • Abstract: Publication date: Available online 22 November 2015
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Debanjan Mukherjee, Pushpa Mishra, Mamata Joshi, Prasoon Kumar Thakur, R.V. Hosur, Gotam K. Jarori
      There are multiple stages in the life cycle of Plasmodium that invade host cells. Molecular machinery involved is such host-pathogen interactions constitute excellent drug targets and/or vaccine candidates. A screen using a phage display library has previously demonstrated presence of enolase on the surface of the Plasmodium ookinete. Phage-displayed peptides that bound to the ookinete contained a conserved motif (PWWP) in their sequence. Here, direct binding of these peptides with recombinant P. falciparum enolase (rPfeno) was investigated. These peptides showed specific binding to rPfeno, but failed to bind to other enolases. Plasmodium spp enolases are distinct in having an insert of five amino acids (104EWGWS108) that is not found in host enolases. The possibility of this insert being the recognition motif for the PWWP containing peptides was examined, (i) by comparing the binding of the peptides with rPfeno and a deletion variant Δ-rPfeno lacking 104EWGWS108, (ii) by measuring the changes in proton chemical shifts of PWWP peptides on binding to different enolases and (iii) by inter-molecular docking experiment to locate the peptide binding site. Results from these studies showed that the pentapeptide insert of Pfeno indeed constitutes the binding site for the PWWP domain containing peptide ligands. Search for sequences homologous to phage displayed peptides among peritrophic matrix proteins resulted in identification of perlecan, laminin, peritrophin and spacran. The possibility of these PWWP domain-containing proteins in the peritrophic matrix of insect gut to interact with ookinete cell surface enolase and facilitate the invasion of mosquito midgut epithelium is discussed.
      Graphical abstract image

      PubDate: 2015-11-22T14:48:09Z
       
  • Identification of the silkworm quail gene reveals a crucial role of a
           receptor guanylyl cyclase in larval pigmentation
    • Abstract: Publication date: Available online 10 November 2015
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Masashi Yuasa, Takashi Kiuchi, Yutaka Banno, Susumu Katsuma, Toru Shimada
      Diverse color patterns on the integument of lepidopteran larvae play important roles in their survival through camouflage, mimicry, sexual signaling, and aposematism. In the silkworm Bombyx mori, many color pattern variations have been preserved in inbred strains making them a good model for elucidating the molecular mechanisms that underlie color pattern formation. In this study, we focused on the silkworm quail (q) mutant, which exhibits abnormalities in multiple pigment biosynthesis pathways. Positional cloning of the q gene revealed that disruption of a guanylyl cyclase gene, BmGC-I, is responsible for its abnormal pigmentation. In q mutants, we identified a 16-bp deletion in the BmGC-I transcript, resulting in the production of a premature stop codon. Knockout of the BmGC-I gene resulted in the q-like abnormal pigmentation, thereby demonstrating that the BmGC-I gene is involved in the pigment biosynthesis pathway in the integument. Moreover, quantitative reverse transcription polymerase chain reaction showed that BmGC-I was strongly expressed in the fourth instar on day 2. Our results suggest that BmGC-I deficiency affects the pigment biosynthesis pathway, which supports the involvement of guanylyl cyclase in larval coloration.
      Graphical abstract image

      PubDate: 2015-11-14T16:09:25Z
       
  • The cytochrome P450 CYP6P4 is responsible for the high pyrethroid
           resistance in knockdown resistance-free Anopheles arabiensis
    • Abstract: Publication date: Available online 6 November 2015
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Sulaiman S. Ibrahim, Jacob M. Riveron, Robert Stott, Helen Irving, Charles S. Wondji
      Pyrethroid insecticides are the front line vector control tools used in bed nets to reduce malaria transmission and its burden. However, resistance in major vectors such as Anopheles arabiensis is posing a serious challenge to the success of malaria control. Herein, we elucidated the molecular and biochemical basis of pyrethroid resistance in a knockdown resistance-free Anopheles arabiensis population from Chad, Central Africa. Using heterologous expression of P450s in E. coli coupled with metabolism assays we established that the over-expressed P450 CYP6P4, located in the major pyrethroid resistance (rp1) quantitative trait locus (QTL), is responsible for resistance to Type I and Type II pyrethroid insecticides, with the exception of deltamethrin, in correlation with field resistance profile. However, CYP6P4 exhibited no metabolic activity towards non-pyrethroid insecticides, including DDT, bendiocarb, propoxur and malathion. Combining fluorescent probes inhibition assays with molecular docking simulation, we established that CYP6P4 can bind deltamethrin but cannot metabolise it. This is possibly due to steric hindrance because of the large vdW radius of bromine atoms of the dihalovinyl group of deltamethrin which docks into the heme catalytic centre. The establishment of CYP6P4 as a partial pyrethroid resistance gene explained the observed field resistance to permethrin, and its inability to metabolise deltamethrin probably explained the high mortality from deltamethrin exposure in the field populations of this Sudano-Sahelian An. arabiensis. These findings describe the heterogeneity in resistance towards insecticides, even from the same class, highlighting the need to thoroughly understand the molecular basis of resistance before implementing resistance management/control tools.
      Graphical abstract image

      PubDate: 2015-11-06T15:56:58Z
       
  • Very high-density lipoprotein and vitellin as carriers of novel
           biliverdins IXα with a farnesyl side-chain presumably derived from
           heme A in Spodoptera littoralis
    • Abstract: Publication date: Available online 4 November 2015
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Hartmut Kayser, Manfred Nimtz, Philippe Ringler, Shirley A. Müller
      Bilins in complex with specific proteins play key roles in many forms of life. Biliproteins have also been isolated from insects; however, structural details are rare and possible functions largely unknown. Recently, we identified a high-molecular weight biliprotein from a moth, Cerura vinula, as an arylphorin-type hexameric storage protein linked to a novel farnesyl biliverdin IXα; its unusual structure suggests formation by cleavage of mitochondrial heme A. In the present study of another moth, Spodoptera littoralis, we isolated two different biliproteins. These proteins were identified as a very high-density lipoprotein (VHDL) and as vitellin, respectively, by mass spectrometric sequencing. Both proteins are associated with three different farnesyl biliverdins IXα: the one bilin isolated from C. vinula and two new structurally closely related bilins, supposed to be intermediates of heme A degradation. The different bilin composition of the two biliproteins suggests that the presumed oxidations at the farnesyl side-chain take place mainly during egg development. The egg bilins are supposedly transferred from hemolymph VHDL to vitellin in the female. Both biliproteins show strong induced circular dichroism activity compatible with a predominance of the M-conformation of the bilins. This conformation is opposite to that of the arylphorin-type biliprotein from C. vinula. Electron microscopy of the VHDL-type biliprotein from S. littoralis provided a preliminary view of its structure as a homodimer and confirmed the biochemically determined molecular mass of ∼350 kDa. Further, images of S. littoralis hexamerins revealed a 2x3 construction identical to that known from the hexamerin from C. vinula.
      Graphical abstract image

      PubDate: 2015-11-06T15:56:58Z
       
  • Metabolomic profiling of permethrin-treated Drosophila melanogaster
           identifies a role for tryptophan catabolism in insecticide survival
    • Abstract: Publication date: Available online 22 October 2015
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Robert A. Brinzer, Louise Henderson, Alan A. Marchiondo, Debra J. Woods, Shireen A. Davies, Julian A.T. Dow
      Insecticides and associated synergists are rapidly losing efficacy in target insect pest populations making the discovery of alternatives a priority. To discover novel targets for permethrin synergists, metabolomics was performed on permethrin-treated Drosophila melanogaster. Changes were observed in several metabolic pathways including those for amino acids, glycogen, glycolysis, energy, nitrogen, NAD+, purine, pyrimidine, lipids and carnitine. Markers for acidosis, ammonia stress, oxidative stress and detoxification responses were also observed. Many of these changes had not been previously characterized after permethrin exposure. From the altered pathways, tryptophan catabolism was selected for further investigation. The knockdown of some tryptophan catabolism genes (vermilion, cinnabar and CG6950) in the whole fly and in specific tissues including fat body, midgut and Malpighian tubules using targeted RNAi resulted in altered survival phenotypes against acute topical permethrin exposure. The knockdown of vermilion, cinnabar and CG6950 in the whole fly also altered survival phenotypes against chronic oral permethrin, fenvalerate, DDT, chlorpyriphos and hydramethylnon exposure. Thus tryptophan catabolism has a previously uncharacterized role in defence against insecticides, and shows that metabolomics is a powerful tool for target identification in pesticide research.
      Graphical abstract image

      PubDate: 2015-10-29T13:08:49Z
       
  • What is an epitheliome, anyway'
    • Abstract: Publication date: Available online 28 October 2015
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Julian A.T. Dow, Shireen A. Davies



      PubDate: 2015-10-29T13:08:49Z
       
  • Probing the chemical mechanism and critical regulatory amino acid residues
           of Drosophila melanogaster arylalkylamine N-acyltransferase like 2
    • Abstract: Publication date: November 2015
      Source:Insect Biochemistry and Molecular Biology, Volume 66
      Author(s): Daniel R. Dempsey, Anne-Marie Carpenter, Santiago Rodriguez Ospina, David J. Merkler
      Arylalkylamine N-acyltransferase like 2 (AANATL2) catalyzes the formation of N-acylarylalkylamides from the corresponding acyl-CoA and arylalkylamine. The N-acylation of biogenic amines in Drosophila melanogaster is a critical step for the inactivation of neurotransmitters, cuticle sclerotization, and melatonin biosynthesis. In addition, D. melanogaster has been used as a model system to evaluate the biosynthesis of fatty acid amides: a family of potent cell signaling lipids. We have previously showed that AANATL2 catalyzes the formation of N-acylarylakylamides, including long-chain N-acylserotonins and N-acyldopamines. Herein, we define the kinetic mechanism for AANATL2 as an ordered sequential mechanism with acetyl-CoA binding first followed by tyramine to generate the ternary complex prior to catalysis. Bell shaped kcat,app – acetyl-CoA and (kcat/Km)app – acetyl-CoA pH-rate profiles identified two apparent pKa,app values of ∼7.4 and ∼8.9 that are critical to catalysis, suggesting the AANATL2-catalyzed formation of N-acetyltyramine occurs through an acid/base chemical mechanism. Site-directed mutagenesis of a conserved glutamate that corresponds to the catalytic base for other D. melanogaster AANATL enzymes did not produce a substantial depression in the kcat,app value nor did it abolish the pKa,app value attributed to the general base in catalysis (pKa ∼7.4). These data suggest that AANATL2 catalyzes the formation of N-acylarylalkylamides using either different catalytic residues or a different chemical mechanism relative to other D. melanogaster AANATL enzymes. In addition, we constructed other site-directed mutants of AANATL2 to help define the role of targeted amino acids in substrate binding and/or enzyme catalysis.
      Graphical abstract image

      PubDate: 2015-10-29T13:08:49Z
       
  • Differential interactions of 5-(4-piperidyl)-3-isoxazolol analogues with
           insect γ-aminobutyric acid receptors leading to functional
           selectivity
    • Abstract: Publication date: Available online 8 October 2015
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Genyan Liu, Bente Frølund, Fumiyo Ozoe, Yoshihisa Ozoe
      γ-Aminobutyric acid (GABA) receptors (GABARs) mediate fast inhibitory synaptic transmission and are also targets for drugs and insecticides. To better understand the molecular interactions of ligands with the orthosteric sites of GABARs, we examined 4-aryl/arylalkyl-5-(4-piperidyl)-3-isoxazolol, 4-aryl-5-(4-piperidyl)-3-isothiazolol, and 5-aryl-4-(4-piperidyl)-1-hydroxypyrazole for their antagonism with regard to three insect GABARs. The 3-isoxazolol was preferable to the 3-isothiazolol and 1-hydroxypyrazole in antagonism to common cutworm and housefly GABARs. Of the tested analogues, 4-(3-biphenylyl)-5-(4-piperidyl)-3-isoxazolol (2a) displayed the greatest antagonism for common cutworm and housefly GABARs, with IC50 values of 3.4 and 10.2 μM, respectively. In contrast to the antagonism of the two GABARs, 2a showed partial agonism for the case of small brown planthopper GABARs, with an EC50 value of 31.3 μM. Homology models and docking simulations revealed that a cation-π interaction between an analogue and an Arg residue in loop C or E of the orthosteric site is a key component of antagonism. This specific phenomenon was lacking in the interactions between 2a and the orthosteric site of small brown planthopper GABARs. These findings provide important insights into designing and developing novel drugs and insecticides.
      Graphical abstract image

      PubDate: 2015-10-09T13:55:47Z
       
  • Towards an understanding of the structural basis for insect olfaction by
           odorant receptors
    • Abstract: Publication date: Available online 28 September 2015
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Colm Carraher, Julie Dalziel, Melissa D. Jordan, David L. Christie, Richard D. Newcomb, Andrew V. Kralicek
      Insects have co-opted a unique family of seven transmembrane proteins for odour sensing. Odorant receptors are believed to have evolved from gustatory receptors somewhere at the base of the Hexapoda and have expanded substantially to become the dominant class of odour recognition elements within the Insecta. These odorant receptors comprise an obligate co-receptor, Orco, and one of a family of highly divergent odorant “tuning” receptors. The two subunits are thought to come together at some as-yet unknown stoichiometry to form a functional complex that is capable of both ionotropic and metabotropic signalling. While there are still no 3D structures for these proteins, site-directed mutagenesis, resonance energy transfer, and structural modelling efforts, all mainly on Drosophila odorant receptors, are beginning to inform hypotheses of their structures and how such complexes function in odour detection. Some of the loops, especially the second extracellular loop that has been suggested to form a lid over the binding pocket and the extracellular regions of some transmembrane helices, especially the third and to a less extent the sixth and seventh, have been implicated in ligand recognition in tuning receptors. The possible interaction between Orco and tuning receptor subunits through the final intracellular loop and the adjacent transmembrane helices is thought to be important for transducing ligand binding into receptor activation. Potential phosphorylation sites and a calmodulin binding site in the second intracellular loop of Orco are also thought to be involved in regulating channel gating. A number of new methods have recently been developed to express and purify insect odorant receptor subunits in recombinant expression systems. These approaches are enabling high throughput screening of receptors for agonists and antagonists in cell-based formats, as well as producing protein for the application of biophysical methods to resolve the 3D structure of the subunits and their complexes.
      Graphical abstract image

      PubDate: 2015-10-01T06:21:46Z
       
  • A novel calcium-independent cellular PLA2 acts in insect immunity and
           larval growth
    • Abstract: Publication date: Available online 30 September 2015
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Youngjin Park, Sunil Kumar, Rahul Kanumuri, David Stanley, Yonggyun Kim
      Phospholipase A2 (PLA2) catalyzes the position-specific hydrolysis of fatty acids linked to the sn-2 position of phospholipids (PLs). PLA2s make up a very large superfamily, with more than known 15 groups, classified into secretory PLA2 (sPLA2), Ca2+-dependent cellular PLA2 (sPLA2) and Ca2+-independent cellular PLA2 (iPLA2). Only a few insect sPLA2s, expressed in venom glands and immune tissues, have been characterized at the molecular level. This study aimed to test our hypothesis that insects express iPLA2, using the beet armyworm, Spodoptera exigua, our model insect. Substantial PLA2 activities under calcium-free condition were recorded in several larval tissue preparations. The PLA2 activity was significantly reduced in reactions conducted in the presence of a specific iPLA2 inhibitor, bromoenol lactone (BEL). Analysis of a S. exigua hemocyte transcriptome identified a candidate iPLA2 gene (SeiPLA 2 -A). The open reading frame encoded 816 amino acid residues with a predicted molecular weight of 90.5 kDa and 6.15 pI value. Our phylogenetic analysis clustered SeiPLA2-A with the other vertebrate iPLA2s. SeiPLA 2 -A was expressed in all tissues we examined, including hemocytes, fat body, midgut, salivary glands, Malpighian tubules and epidermis. Heterologous expression in Sf9 cells indicated that SeiPLA2-A was localized in cytoplasm and exhibited significant PLA2 activity, which was independent of Ca2+ and inhibited by BEL. RNA interference (RNAi) of SeiPLA 2 -A using its specific dsRNA in the fifth instar larvae significantly suppressed iPLA2 expression and enzyme activity. dsSeiPLA2-A-treated larvae exhibited significant loss of cellular immune response, measured as nodule formation in response to bacterial challenge, and extended larval-to-pupal developmental time. These results support our hypothesis, showing that SeiPLA2-A predicted from the transcriptome analysis catalyzes hydrolysis of fatty acids from cellular PLs and plays crucial physiological roles in insect immunity and larval growth.
      Graphical abstract image

      PubDate: 2015-10-01T06:21:46Z
       
  • Molecular characterization of the gene feminizer in the stingless bee
           Melipona interrupta (Hymenoptera: Apidae) reveals association to sex and
           caste development
    • Abstract: Publication date: Available online 21 September 2015
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Diana V. Brito, Carlos Gustavo N. Silva, Martin Hasselmann, Luciana S. Viana, Spartaco Astolfi-Filho, Gislene A. Carvalho-Zilse
      In highly eusocial insects, development of reproductive traits is regulated not only by sex determination pathway, but it also depends on caste fate. The molecular basis of both mechanisms in stingless bees and possible interaction with each other is still obscure. Here, we investigate sex determination in Melipona interrupta, focusing on characterization and expression analysis of the feminizer gene (Mi-fem), and its association to a major component of caste determination, the Juvenile Hormone (JH). We present evidence that Mi-fem mRNA is sex-specifically spliced in which only the female splice variant encodes the full length protein, following the same principle known for other bee species. We quantified Mi-fem expression among developmental stages, sexes and castes. Mi-fem expression varies considerably throughout development, with higher expression levels in embryos. Also, fem levels in pupae and newly-emerged adults were significantly higher in queens than workers and males. Finally, we ectopically applied JH in cocoon spinning larvae, which correspond to the time window where queen/worker phenotypes diverge. We observed a significantly increase in Mi-fem expression compared to control groups. Since up to 100% of females turn into queens when treated with JH (while control groups are composed mainly of workers), we propose that fem might act to regulate queens’ development. Our findings provide support for the conserved regulatory function of fem in Melipona bees and demonstrate a significant correlation between key elements of sex and caste determination pathways, opening the avenue to further investigate the molecular basis of these complex traits.
      Graphical abstract image

      PubDate: 2015-09-22T22:24:33Z
       
  • BmBR-C Z4 is an upstream regulatory factor of BmPOUM2 controlling the
           pupal specific expression ofBmWCP4 in the silkworm, Bombyx mori
    • Abstract: Publication date: Available online 10 September 2015
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Huimin Deng, Kangkang Niu, Jialing Zhang, Qili Feng
      20-hydroxyecdysone (20E)-induced expression of the wing disc cuticle protein gene BmWCP4 was mediated by the transcription factor BmPOUM2, which binds to the cis-response elements (CREs) of BmWCP4 gene in Bombyx mori. In this study we report the regulation of BmPOUM2. RT-PCR analysis indicated that in response to 20E, BmPOUM2 was expressed at higher levels in the wing discs during the pre-pupal and mid-pupal stages than other stages and the expression pattern of BmBR-C Z1, BmBR-C Z2 and BmBR-C Z4 was in tandem with the expression of BmPOUM2. BmBR-C Z4 was induced by 20E in the wing discs, whereas BmBR-C Z1 and BmBR-C Z2 were not. Three potential BR-C Z4 cis-response elements (CREs) were identified in the promoter region of BmPOUM2. The expression of BmPOUM2 mRNA and protein was increased by the over-expression of BmBR-C Z4 in BmN cells, which acted at the promoter of BmPOUM2. Electrophoretic mobility shift assay (EMSA) and the luciferase activity analysis under the control of wild-type and mutants of the BR-C Z4 CREs suggested that BmBR-C Z4 protein bound to the predicted BRC-Z4 CRE C (-684∼-660). Taken together the data suggest that BmBR-C Z4 is a direct upstream regulator of BmPOUM2 and regulates the pupal-specific expression of BmWCP4 through BmPOUM2.
      Graphical abstract image

      PubDate: 2015-09-19T06:37:19Z
       
  • A reference gene set for chemosensory receptor genes of Manduca sexta
    • Abstract: Publication date: Available online 11 September 2015
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Christopher Koenig, Ariana Hirsh, Sascha Bucks, Christian Klinner, Heiko Vogel, Aditi Shukla, Jennifer H. Mansfield, Brian Morton, Bill S. Hansson, Ewald Grosse-Wilde
      The order of Lepidoptera has historically been crucial for chemosensory research, with many important advances coming from the analysis of species like Bombyx mori or the tobacco hornworm, Manduca sexta. Specifically M. sexta has long been a major model species in the field, especially regarding the importance of olfaction in an ecological context, mainly the interaction with its host plants. In recent years transcriptomic data has led to the discovery of members of all major chemosensory receptor families in the species, but the data was fragmentary and incomplete. Here we present the analysis of the newly available high-quality genome data for the species, supplemented by additional transcriptome data to generate a high quality reference gene set for the three major chemosensory receptor gene families, the gustatory (GR), olfactory (OR) and antennal ionotropic receptors (IR). Coupled with gene expression analysis our approach allows association of specific receptor types and behaviors, like pheromone and host detection. The dataset will provide valuable support for future analysis of these essential chemosensory modalities in this species and in Lepidoptera in general.
      Graphical abstract image

      PubDate: 2015-09-19T06:37:19Z
       
 
 
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