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  Subjects -> BIOLOGY (Total: 2601 journals)
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BIOCHEMISTRY (192 journals)                  1 2     

AAPS PharmSciTech     Hybrid Journal   (Followers: 6)
Acetic Acid Bacteria     Open Access   (Followers: 1)
ACS Chemical Biology     Full-text available via subscription   (Followers: 251)
ACS Chemical Neuroscience     Full-text available via subscription   (Followers: 13)
Acta Crystallographica Section D : Biological Crystallography     Hybrid Journal   (Followers: 8)
Acta Crystallographica Section F: Structural Biology Communications     Hybrid Journal   (Followers: 5)
Advances and Applications in Bioinformatics and Chemistry     Open Access   (Followers: 7)
Advances in Biological Chemistry     Open Access   (Followers: 5)
Advances in Carbohydrate Chemistry and Biochemistry     Full-text available via subscription   (Followers: 6)
Advances in Plant Biochemistry and Molecular Biology     Full-text available via subscription   (Followers: 6)
Advances in Protein Chemistry and Structural Biology     Full-text available via subscription   (Followers: 10)
African Journal of Biochemistry Research     Open Access  
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: 6)
American Journal of Biochemistry and Biotechnology     Open Access   (Followers: 147)
American Journal of Biochemistry and Molecular Biology     Open Access   (Followers: 11)
Amino Acids     Hybrid Journal   (Followers: 7)
Analytical Biochemistry     Hybrid Journal   (Followers: 171)
Annals of Clinical Biochemistry     Hybrid Journal   (Followers: 1)
Annual Review of Biochemistry     Full-text available via subscription   (Followers: 28)
Annual Review of Chemical and Biomolecular Engineering     Full-text available via subscription   (Followers: 10)
Applied Biochemistry and Biotechnology     Hybrid Journal   (Followers: 18)
Applied Biochemistry and Microbiology     Hybrid Journal   (Followers: 7)
Applied Organometallic Chemistry     Hybrid Journal   (Followers: 4)
Archives of Biochemistry and Biophysics     Hybrid Journal   (Followers: 9)
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)
Bangladesh Journal of Medical Biochemistry     Open Access   (Followers: 2)
BBA Clinical     Open Access  
BBR : Biochemistry and Biotechnology Reports     Open Access   (Followers: 4)
Biochemical and Biophysical Research Communications     Hybrid Journal   (Followers: 13)
Biochemical and Molecular Medicine     Full-text available via subscription   (Followers: 2)
Biochemical Engineering Journal     Hybrid Journal   (Followers: 8)
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Biochemical Society Transactions     Full-text available via subscription   (Followers: 2)
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Biochemistry     Full-text available via subscription   (Followers: 177)
Biochemistry (Moscow)     Hybrid Journal   (Followers: 3)
Biochemistry (Moscow) Supplement Series A: Membrane and Cell Biology     Hybrid Journal   (Followers: 4)
Biochemistry (Moscow) Supplemental Series B: Biomedical Chemistry     Hybrid Journal   (Followers: 4)
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: 4)
Biochimica et Biophysica Acta (BBA) - Molecular and Cell Biology of Lipids     Hybrid Journal   (Followers: 3)
Biochimica et Biophysica Acta (BBA) - Molecular Basis of Disease     Hybrid Journal   (Followers: 17)
Biochimica et Biophysica Acta (BBA) - Molecular Cell Research     Hybrid Journal   (Followers: 5)
Biochimie     Hybrid Journal   (Followers: 4)
Bioconjugate Chemistry     Full-text available via subscription   (Followers: 14)
BioDrugs     Full-text available via subscription   (Followers: 7)
Bioelectrochemistry     Hybrid Journal   (Followers: 3)
Biofuels     Hybrid Journal   (Followers: 7)
Biogeochemistry     Hybrid Journal   (Followers: 5)
BioInorganic Reaction Mechanisms     Full-text available via subscription   (Followers: 1)
Biokemistri     Open Access  
Biological Chemistry     Partially Free   (Followers: 11)
Biomedicines     Open Access   (Followers: 1)
BioMolecular Concepts     Full-text available via subscription   (Followers: 2)
Bioscience, Biotechnology, and Biochemistry     Hybrid Journal   (Followers: 6)
Biosimilars     Open Access   (Followers: 1)
Biotechnology and Applied Biochemistry     Hybrid Journal   (Followers: 17)
BMC Biochemistry     Open Access   (Followers: 8)
BMC Chemical Biology     Open Access   (Followers: 4)
Carbohydrate Polymers     Hybrid Journal   (Followers: 8)
Cell Biochemistry and Biophysics     Hybrid Journal   (Followers: 6)
Cell Biochemistry and Function     Hybrid Journal   (Followers: 3)
Cellular Physiology and Biochemistry     Open Access   (Followers: 3)
Central European Journal of Chemistry     Hybrid Journal   (Followers: 5)
ChemBioChem     Hybrid Journal   (Followers: 2)
Chemical and Biological Technologies for Agriculture     Open Access  
Chemical Biology & Drug Design     Hybrid Journal   (Followers: 23)
Chemical Engineering Journal     Hybrid Journal   (Followers: 18)
Chemical Senses     Hybrid Journal   (Followers: 1)
Chemical Speciation and Bioavailability     Full-text available via subscription   (Followers: 1)
Chemico-Biological Interactions     Hybrid Journal   (Followers: 2)
Chemistry & Biodiversity     Hybrid Journal   (Followers: 5)
Chemistry & Biology     Full-text available via subscription   (Followers: 16)
Chemistry and Ecology     Hybrid Journal   (Followers: 1)
Clinical Biochemist Reviews     Full-text available via subscription   (Followers: 1)
Clinical Biochemistry     Hybrid Journal   (Followers: 3)
Clinical Chemistry and Laboratory Medicine     Full-text available via subscription   (Followers: 3)
Clinical Lipidology     Full-text available via subscription  
Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology     Hybrid Journal   (Followers: 5)
Comparative Biochemistry and Physiology Part B: Biochemistry and Molecular Biology     Hybrid Journal   (Followers: 2)
Comparative Biochemistry and Physiology Part C: Toxicology & Pharmacology     Hybrid Journal   (Followers: 4)
Comparative Biochemistry and Physiology Part D: Genomics and Proteomics     Hybrid Journal   (Followers: 3)
Comprehensive Biochemistry     Full-text available via subscription   (Followers: 1)
Computational Biology and Chemistry     Hybrid Journal   (Followers: 8)
Critical Reviews in Biochemistry and Molecular Biology     Hybrid Journal   (Followers: 2)
Current Chemical Biology     Hybrid Journal   (Followers: 2)
Current Opinion in Chemical Biology     Hybrid Journal   (Followers: 14)
Current Opinion in Lipidology     Hybrid Journal   (Followers: 2)
DNA Barcodes     Open Access  
Doklady Biochemistry and Biophysics     Hybrid Journal   (Followers: 2)
Doklady Chemistry     Hybrid Journal  
Egyptian Journal of Biochemistry and Molecular Biology     Full-text available via subscription  

        1 2     

Journal Cover Insect Biochemistry and Molecular Biology
   [5 followers]  Follow    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
     ISSN (Print) 0965-1748
     Published by Elsevier Homepage  [2563 journals]   [SJR: 1.333]   [H-I: 69]
  • Allelic-specific Expression in Relation to Bombyx mori resistance to Bt
           toxin
    • Abstract: Publication date: Available online 12 August 2014
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Yazhou Chen , Muwang Li , Iftakher Islam , Lang You , Yueqiang Wang , Zhiqian Li , Lin Ling , Baosheng Zeng , Jun Xu , Yongping Huang , Anjiang Tan
      Understanding the mechanism of Bt resistance is one of the key elements of the effective application of Bt in pest control. The lepidopteran model insect, the silkworm, demonstrates qualities that make it an ideal species to use in achieving this understanding. We screened 45 strains of silkworm (Bombyx mori) using a Cry1Ab toxin variant. The sensitivity levels of the strains varied over a wide range. A resistant strain (P50) and a phylogenetically related susceptible strain (Dazao) were selected to profile the expressions of 12 Bt resistance-related genes. The SNPs in these genes were detected based on EST analysis and were validated by allelic-specific PCR. A comparison of allelic-specific expression between P50 and Dazao showed that the transcript levels of heterozygous genes containing two alleles rather than an imbalanced allelic expression contribute more to the resistance of P50 against Bt. The responses of the allelic-specific expression to Bt in hybrid larvae were then investigated. The results showed that the gene expression pattern of an ATP-binding cassette transporter C2 (ABCC2) and an aminopeptidase N (APN3), changed in an allelic-specific manner, with the increase of the resistant allele expression correlated with larval survival. The results suggest that a trans-regulatory mechanism in ABCC2 and APN3 allelic-specific expression is involved in the insect’s response to the Bt toxin. The potential role of allelic-specific gene regulation in insect resistance to Bt toxins is discussed.
      Graphical abstract image

      PubDate: 2014-08-16T01:24:16Z
       
  • Biosynthetic pathway of the phytohormone auxin in insects and screening of
           its inhibitors
    • Abstract: Publication date: Available online 8 August 2014
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Hiroyoshi Suzuki , Junpei Yokokura , Tsukasa Ito , Ryoma Arai , Chiaki Yokoyama , Hiroaki Toshima , Shinji Nagata , Tadao Asami , Yoshihito Suzuki
      Insect galls are abnormal plant tissues induced by galling insects. The galls are used for food and habitation, and the phytohormone auxin, produced by the insects, may be involved in their formation. We found that the silkworm, a non-galling insect, also produces an active form of auxin, indole-3-acetic acid (IAA), by de novo synthesis from tryptophan (Trp). A detailed metabolic analysis of IAA using IAA synthetic enzymes from silkworms indicated an IAA biosynthetic pathway composed of a three-step conversion: Trp → indole-3-acetaldoxime → indole-3-acetaldehyde (IAAld) → IAA, of which the first step is limiting IAA production. This pathway was shown to also operate in gall-inducing sawfly. Screening of a chemical library identified two compounds that showed strong inhibitory activities on the conversion step IAAld → IAA. The inhibitors can be efficiently used to demonstrate the importance of insect-synthesized auxin in gall formation in the future.
      Graphical abstract image

      PubDate: 2014-08-12T00:33:41Z
       
  • MicroRNA Let-7 regulates molting and metamorphosis in the silkworm, Bombyx
           mori
    • Abstract: Publication date: Available online 9 July 2014
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Lin Ling , Xie Ge , Zhiqian Li , Baosheng Zeng , Jun Xu , Abu F.M. Aslam , Qisheng Song , Peng Shang , Yongping Huang , Anjiang Tan
      MicroRNAs (miRNAs) are a class of endogenous, non-coding, regulatory RNA molecules that post-transcriptionally regulate gene expression by binding to the 3′UTRs of mRNA targets and thus cause their degradation or translational inhibition. In insects, important roles of miRNAs in various biological processes have been demonstrated in Drosophila melanogaster. However, biological roles of miRNAs are barely unveiled in the majority of insect species due to limited genetic tools. In the present study, we introduce the transgenic miRNA sponge (miR-SP) technology combining with the binary GAL4/UAS system in the domesticated silkworm, Bombyx mori, to exploit the biological function of an evolutionally conserved miRNA, let-7. We successfully established transgenic silkworm lines in which a miRNA sponge construct targeting BmLet-7 seed region was expressed in a ubiquitous manner directed by A3-GAL4 driver. Transgenic animals showed decreased expression of BmLet-7, leading to developmental arrestment during the larval–larval and larval–pupal transition. Simultaneously, expression levels of the predicted BmLet-7 target genes, FTZ-F1 and Eip74EF (E74), key regulatory factors in the ecdysone pathway, were elevated in transgenic animals. The current study is the first report on application of the transgenic miR-SP technology in non-drosophilid insects, which will not only contribute to better understanding of let-7 biological roles, but also greatly facilitate future miRNA functional analysis in insects.
      Graphical abstract image

      PubDate: 2014-07-26T22:00:00Z
       
  • Identification of candidate odorant degrading gene/enzyme systems in the
           antennal transcriptome of Drosophila melanogaster
    • Abstract: Publication date: Available online 16 July 2014
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Faisal Younus , Thomas Chertemps , Stephen L. Pearce , Gunjan Pandey , Françoise Bozzolan , Christopher W. Coppin , Robyn J. Russell , Martine Maïbèche-Coisne , John G. Oakeshott
      The metabolism of volatile signal molecules by odorant degrading enzymes (ODEs) is crucial to the ongoing sensitivity and specificity of chemoreception in various insects, and a few specific esterases, cytochrome P450s, glutathione S-transferases (GSTs) and UDP-glucosyltransferases (UGTs) have previously been implicated in this process. Significant progress has been made in characterizing ODEs in Lepidoptera but very little is known about them in Diptera, including in Drosophila melanogaster, a major insect model. We have therefore carried out a transcriptomic analysis of the antennae of D. melanogaster in order to identify candidate ODEs. Virgin male and female and mated female antennal transcriptomes were determined by RNAseq. As with the Lepidoptera, we found that many esterases, cytochrome P450 enzymes, GSTs and UGTs are expressed in D. melanogaster antennae. As olfactory genes generally show selective expression in the antennae, a comparison to previously published transcriptomes for other tissues has been performed, showing preferential expression in the antennae for one esterase, JHEdup, one cytochrome P450, CYP308a1, and one GST, GSTE4. These largely uncharacterized enzymes are now prime candidates for ODE functions. Jhedup was expressed heterologously and found to have high catalytic activity against a chemically diverse group of known ester odorants for this species. This is a finding consistent with an ODE although it might suggest a general role in clearing several odorants rather than a specific role in clearing a particular odorant. Our findings do not preclude the possibility of odorant degrading functions for other antennally expressed esterases, P450s, GSTs and UGTs but, if so, they suggest that these enzymes also have additional functions in other tissues.
      Graphical abstract image

      PubDate: 2014-07-26T22:00:00Z
       
  • Two major cuticular proteins are required for assembly of horizontal
           laminae and vertical pore canals in rigid cuticle of Tribolium castaneum
    • Abstract: Publication date: Available online 18 July 2014
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Mi Young Noh , Karl J. Kramer , Subbaratnam Muthukrishnan , Michael R. Kanost , Richard W. Beeman , Yasuyuki Arakane
      The insect exoskeleton is composed of cuticle primarily formed from structural cuticular proteins (CPs) and the polysaccharide chitin. Two CPs, TcCPR27 and TcCPR18, are major proteins present in the elytron (highly sclerotized and pigmented modified forewing) as well as the pronotum (dorsal sclerite of the prothorax) and ventral abdominal cuticle of the red flour beetle, Tribolium castaneum. Both CPs belong to the CPR family, which includes proteins that have an amino acid sequence motif known as the Rebers & Riddiford (R&R) consensus sequence. Injection of double-stranded RNA (dsRNA) for TcCPR27 and TcCPR18 resulted in insects with shorter, wrinkled, warped and less rigid elytra than those from control insects. To gain a more comprehensive understanding of the roles of CPs in cuticle assembly, we analyzed for the precise localization of TcCPR27 and the ultrastructural architecture of cuticle in TcCPR27- and TcCPR18-deficient elytra. Transmission electron microscopic analysis combined with immunodetection using gold-labeled secondary antibody revealed that TcCPR27 is present in dorsal elytral procuticle both in the horizontal laminae and in vertical pore canals. dsRNA-mediated RNA interference (RNAi) of TcCPR27 resulted in abnormal electron-lucent laminae and pore canals in elytra except for the boundary between these two structures in which electron-dense molecule(s) apparently accumulated. Insects subjected to RNAi for TcCPR18 also had disorganized laminae and pore canals in the procuticle of elytra. Similar ultrastructural defects were also observed in other body wall regions with rigid cuticle such as the thorax and legs of adult T. castaneum. TcCPR27 and TcCPR18 are required for proper formation of the horizontal chitinous laminae and vertical pore canals that are critical for formation and stabilization of rigid adult cuticle.
      Graphical abstract image

      PubDate: 2014-07-26T22:00:00Z
       
  • Wnt/β-catenin signaling regulates Helicoverpa armigera pupal
           development by up-regulating c-Myc and AP-4
    • Abstract: Publication date: Available online 16 July 2014
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Wei Chen , Wei-Hua Xu
      Seasonally changing environmental conditions perceived by insect brains can be converted into hormonal signals that prompt insects to make a decision to develop or enter developmental arrest (diapause). Diapause is a complex physiological response, and many signaling pathways may participate in its regulation. However, little is known about these regulatory pathways. In this study, we cloned four genes related to the Wnt/β-catenin signaling pathway from Helicoverpa armigera, a pupal diapause species. Western blotting shows that expression of Har-Wnt1, Har-β-catenin, and Har-c-Myc are higher in non-diapause pupal brains than in diapause-destined brains. Har-Wnt1 can promote the accumulation of Har-β-catenin in the nucleus, and Har-β-catenin in turn increases the expression of Har-c-Myc. The blockage of Wnt/β-catenin signaling by the inhibitor XAV939 significantly down-regulates Har-β-catenin and Har-c-Myc expression and delays pupal development, suggesting that the Wnt/β-catenin pathway functions in insect development. Furthermore, Har-c-Myc binds to the promoter of Har-AP-4 and regulates its expression. It has been reported that Har-AP-4 activates diapause hormone (DH) expression and that DH up-regulates the growth hormone ecdysteroid for pupal development. Thus, pupal development is regulated by Wnt/catenin signaling through the pathway Wnt-β-catenin-c-Myc-AP-4-DH-ecdysteroid. In contrast, the down-regulation of Wnt/β-catenin signaling is likely to induce insects to enter diapause.
      Graphical abstract image

      PubDate: 2014-07-26T22:00:00Z
       
  • An independent occurrence of the chimeric P450 enzyme CYP337B3 of
           Helicoverpa armigera confers cypermethrin resistance in Pakistan
    • Abstract: Publication date: Available online 24 July 2014
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Akhtar Rasool , Nicole Joußen , Sybille Lorenz , Renate Ellinger , Bernd Schneider , Sher Afzal Khan , Muhammad Ashfaq , David G. Heckel
      The increasing resistance level of insect pest species is a major concern to agriculture worldwide. The cotton bollworm, Helicoverpa armigera, is one of the most important pest species due to being highly polyphagous, geographically widespread, and resistant towards many chemical classes of insecticides. We previously described the mechanism of fenvalerate resistance in Australian populations conferred by the chimeric cytochrome P450 monooxygenase CYP337B3, which arose by unequal crossing-over between CYP337B1 and CYP337B2. Here, we show that this mechanism is also present in the cypermethrin-resistant FSD strain from Pakistan. The Pakistani and the Australian CYP337B3 alleles differ by 18 synonymous and three nonsynonymous SNPs and additionally in the length and sequence of the intron. Nevertheless, the activity of both CYP337B3 proteins is comparable. We demonstrate that CYP337B3 is capable of metabolizing cypermethrin (trans- and especially cis-isomers) to the main metabolite 4'-hydroxycypermethrin, which exhibits no intrinsic toxicity towards susceptible larvae. In a bioassay, CYP337B3 confers a 7-fold resistance towards cypermethrin in FSD larvae compared to susceptible larvae from the Australian TWB strain lacking CYP337B3. Linkage analysis shows that presence of CYP337B3 accounts for most of the cypermethrin resistance in the FSD strain; up-regulation of other P450s in FSD plays no detectable role in resistance. The presence or absence of CYP337B3 can be easily detected by a simple PCR screen, providing a powerful tool to rapidly distinguish resistant from susceptible individuals in the field and to determine the geographical distribution of this resistance gene. Our results suggest that CYP337B3 evolved twice independently by unequal crossing-over between CYP337B2 and two different CYP337B1 alleles.
      Graphical abstract image

      PubDate: 2014-07-26T22:00:00Z
       
  • Effects of chitin synthase double-stranded RNA on molting and oogenesis in
           the Chagas disease vector Rhodnius prolixus
    • Abstract: Publication date: August 2014
      Source:Insect Biochemistry and Molecular Biology, Volume 51
      Author(s): Juliana F. Mansur , Evelyn S.L. Alvarenga , Janaina Figueira-Mansur , Thiago A. Franco , Isabela B. Ramos , Hatisaburo Masuda , Ana C.A. Melo , Mônica F. Moreira
      In this study, we provided the demonstration of the presence of a single CHS gene in the Rhodnius prolixus (a blood-sucking insect) genome that is expressed in adults (integument and ovary) and in the integument of nymphs during development. This CHS gene appears to be essential for epidermal integrity and egg formation in R. prolixus. Because injection of CHS dsRNA was effective in reducing CHS transcript levels, phenotypic alterations in the normal course of ecdysis occurred. In addition, two phenotypes with severe cuticle deformations were observed, which were associated with loss of mobility and lifetime. The CHS dsRNA treatment in adult females affected oogenesis, reducing the size of the ovary and presenting a greater number of atresic oocytes and a smaller number of chorionated oocytes compared with the control. The overall effect was reduced oviposition. The injection of CHS dsRNA modified the natural course of egg development, producing deformed eggs that were dark in color and unable to hatch, distinct from the viable eggs laid by control females. The ovaries, which were examined under fluorescence microscopy using a probe for chitin detection, showed a reduced deposition on pre-vitellogenic and vitellogenic oocytes compared with control. Taken together, these data suggest that the CHS gene is fundamentally important for ecdysis, oogenesis and egg hatching in R. prolixus and also demonstrated that the CHS gene is a good target for controlling Chagas disease vectors.
      Graphical abstract image

      PubDate: 2014-07-26T22:00:00Z
       
  • Chitin deposition on the embryonic cuticle of Rhodnius prolixus: The
           reduction of CHS transcripts by CHS–dsRNA injection in females
           affects chitin deposition and eclosion of the first instar nymph
    • Abstract: Publication date: August 2014
      Source:Insect Biochemistry and Molecular Biology, Volume 51
      Author(s): Paula S. Souza-Ferreira , Juliana F. Mansur , Matheus Berni , Monica F. Moreira , Roberto Eizemberg dos Santos , Helena M. Marcolla Araújo , Wanderley de Souza , Isabela B. Ramos , Hatisaburo Masuda
      In a previous study, we found that the embryonic cuticle of Rhodnius prolixus is a chitin-based structure that helps the first instar nymph to hatch from the chorion. Here, we investigated how the reduction of transcripts induced by CHS dsRNA injection affects R. prolixus embryogenesis and eclosion. Deposition of chitin in the embryonic cuticle begins later at embryogenesis, around day 8, and ends approximately at day 15, when the insects are ready for eclosion. In R. prolixus, chitin deposition follows pari passu with the synthesis of the chitin synthase mRNA, indicating a regulation at the transcriptional level. The reduction of the chitin synthase gene transcripts by the injection of CHS dRNA prevented chitin deposition during embryonic cuticle formation, being lethal to hatching nymphs, which end up dying while stuck in the chorionic border trying to leave the chorion. The successful eclosion rates were reduced by 60% in animals treated with CHS dsRNA when compared to animals injected with a control (dsRNA no related gene or water). We found that the harmful effects on oviposition and eclosion are possibly due to changes in the structure of the embryonic cuticle, as observed by directly comparing the morphology of control and chitin-deficient embryonic cuticles under the transmission electron microscope. The lack of chitin and changes in its morphological characteristics appears to alter the embryonic cuticle physiology and functionality. Additionally, we observed that the effects of CHS dRNA treatment on R. prolixus females lasted up to 3 egg-laying cycles (∼100 days), pointing to R. prolixus as a useful model for developmental studies.
      Graphical abstract image

      PubDate: 2014-07-26T22:00:00Z
       
  • Transgenic sexing system for genetic control of the Australian sheep blow
           fly Lucilia cuprina
    • Abstract: Publication date: August 2014
      Source:Insect Biochemistry and Molecular Biology, Volume 51
      Author(s): Fang Li , Holly A. Wantuch , Rebecca J. Linger , Esther J. Belikoff , Maxwell J. Scott
      The New World screwworm and the Australian sheep blowfly Lucilia cuprina are devastating pests of livestock. The larvae of these species feed on the tissue of the living animal and can cause death if untreated. The sterile insect technique or SIT was used to eradicate screwworm from North and Central America. This inspired efforts to develop strains containing complex chromosomal rearrangements for genetic control of L. cuprina in Australia. Although one field trial was promising, the approach was abandoned due to costs and difficulties in mass rearing the strain. As the efficiency of SIT can be significantly increased if only sterile males are released, we have developed transgenic strains of L. cuprina that carry a dominant tetracycline repressible female lethal genetic system. Lethality is due to overexpression of an auto-regulated tetracycline repressible transactivator (tTA) gene and occurs mostly at the pupal stage. Dominant female lethality was achieved by replacing the Drosophila hsp70 core promoter with a Lucilia hsp70 core promoter-5′UTR for tTA overexpression. The strains carry a dominant strongly expressed marker that will facilitate identification in the field. Interestingly, the sexes could be reliably sorted by fluorescence or color from the early first instar larval stage as females that overexpress tTA also overexpress the linked marker gene. Male-only strains of L. cuprina developed in this study could form the basis for a future genetic control program. Moreover, the system developed for L. cuprina should be readily transferrable to other major calliphorid livestock pests including the New and Old World screwworm.
      Graphical abstract image

      PubDate: 2014-07-26T22:00:00Z
       
  • Molecular characterization of Rhodnius prolixus' embryonic cuticle
    • Abstract: Publication date: August 2014
      Source:Insect Biochemistry and Molecular Biology, Volume 51
      Author(s): Paula S. Souza-Ferreira , Mônica F. Moreira , Geórgia C. Atella , Ana Lúcia Oliveira-Carvalho , Roberto Eizemberg , David Majerowicz , Ana C.A. Melo , Russolina B. Zingali , Hatisaburo Masuda
      The embryonic cuticle (EC) of Rhodnius prolixus envelopes the entire body of the embryo during hatching and provides physical protection, allowing the embryo to pass through a narrow chorionic border. Most of the knowledge about the EC of insects is derived from studies on ultrastructure and secretion processes during embryonic development, and little is known about the molecular composition of this structure. We performed a comprehensive molecular characterization of the major components extracted from the EC of R. prolixus, and we discuss the role of the different molecules that were identified during the eclosion process. The results showed that, similar to the post-embryonic cuticles of insects, the EC of R. prolixus is primarily composed of carbohydrates (57%), lipids (19%), and proteins (8%). Considering only the carbohydrates, chitin is by far the major component (approximately 70%), and it is found primarily along the body of the EC. It is scarce or absent in its prolongations, which are composed of glycosaminoglycans. In addition to chitin, we also identified amino (15%), neutral (12%) and acidic (3%) carbohydrates in the EC of R. prolixus. In addition carbohydrates, we also identified neutral lipids (64.12%) and phospholipids (35.88%). Proteomic analysis detected 68 proteins (55 were identified and 13 are hypothetical proteins) using the sequences in the R. prolixus genome (http://www.vectorbase.org). Among these proteins, 8 out of 15 are associated with cuticle metabolism. These proteins are unequivocally cuticle proteins, and they have been described in other insects. Approximately 35% of the total proteins identified were classified as having a structural function. Chitin-binding protein, amino peptidase, amino acid oxidase, oxidoreductase, catalase and peroxidase are all proteins associated with cuticle metabolism. Proteins known to be cuticle constituents may be related to the function of the EC in assisting the insect during eclosion. To our knowledge, this is the first study to describe the global molecular composition of an EC in insects.
      Graphical abstract image

      PubDate: 2014-07-26T22:00:00Z
       
  • Rapid incorporation of glucosinolates as a strategy used by a herbivore to
           prevent activation by myrosinases
    • Abstract: Publication date: September 2014
      Source:Insect Biochemistry and Molecular Biology, Volume 52
      Author(s): Mohamed K. Abdalsamee , Marco Giampà , Karsten Niehaus , Caroline Müller
      Various plants have a binary defence system that consists of a substrate and a glucosidase, which is activated upon tissue disruption thereby forming reactive hydrolysis products. Insects feeding on such plants have to overcome this binary defence system or prevent the activation. In this study, we investigated the strategy used by a herbivore to deal with such binary defence. We studied, how the larvae of the sawfly Athalia rosae (Hymenoptera: Tenthredinidae) circumvent the activation of glucosinolates by myrosinase enzymes, which are found in their Brassicaceae host plants. Myrosinase activities were low in the front part of the larval gut but activities increased over the gut passage. In contrast, the glucosinolates were only highly concentrated in the first gut part and were rapidly incorporated into the haemolymph before the food reached the second half of the gut. Thus, the uptake and concentration of glucosinolates, i.e., sequestration, must occur in the front part of the gut. Using Matrix Assisted Laser Desorption Ionization-Mass Spectrometry Imaging (MALDI-MSI), we could demonstrate that the incorporated glucosinolate sinalbin circulates in the haemolymph where it accumulates around the Malpighian tubules. This study highlights the pivotal role of the gut of an adapted herbivore as a regulatory functional organ to cope with plant toxins. MALDI-MSI turned out as a highly useful technique to visualise glucosinolates in a herbivore, which has to deal with plants exhibiting a binary defence system, and may be applied to follow the fate of plant metabolites in other insect species in the future.
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      PubDate: 2014-07-26T22:00:00Z
       
  • Editorial Board
    • Abstract: Publication date: August 2014
      Source:Insect Biochemistry and Molecular Biology, Volume 51




      PubDate: 2014-07-26T22:00:00Z
       
  • Functions of Armigeres subalbatus C-type lectins in innate immunity
    • Abstract: Publication date: September 2014
      Source:Insect Biochemistry and Molecular Biology, Volume 52
      Author(s): Xiu-Zhen Shi , Cui-Jie Kang , Song-Jie Wang , Xue Zhong , Brenda T. Beerntsen , Xiao-Qiang Yu
      C-type lectins (CTLs) are a superfamily of calcium-dependent carbohydrate binding proteins containing at least one carbohydrate-recognition domain (CRD) and they are present in almost all metazoans. Insect CTLs may function as pattern-recognition receptors and play important roles in innate immunity. In this study, we selected five AsCTLs from the mosquito Armigeres subalbatus, a natural vector of filarial nematodes, and performed both in vitro and in vivo studies to elucidate their functions in innate immunity. AsCTLMA15, AsCTLGA5 and AsCTL15 were mainly expressed in hemocytes, AsCTL16 was expressed in fat body, while AsCTLMA11 was expressed in both hemocytes and fat body, and only AsCTLMA11 and AsCTL16 were expressed at high levels in adult females. In vitro binding assays showed that all five recombinant AsCTLs could bind to different microbial cell wall components, including lipopolysaccharide (LPS), lipid A, peptidoglycan (PG), lipoteichoic acid (LTA), zymosan and laminarin (beta-1,3-glucan). Recombinant AsCTLs also bound to several Gram-negative and Gram-positive bacteria, and could agglutinate bacterial cells. Injection of double-stranded RNAs (dsRNAs) could significantly reduce expression of the five As CTL mRNAs, and the survival of mosquitoes treated with dsRNA to AsCTLGA5 was significantly decreased after Escherichia coli infection, but did not change significantly after Micrococcus luteus infection compared to the control groups, suggesting that Ar. subalbatus AsCTLGA5 may participate in innate immunity against E. coli.
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      PubDate: 2014-07-26T22:00:00Z
       
  • Krüppel-homolog 1 mediates juvenile hormone action to promote
           vitellogenesis and oocyte maturation in the migratory locust
    • Abstract: Publication date: September 2014
      Source:Insect Biochemistry and Molecular Biology, Volume 52
      Author(s): Jiasheng Song , Zhongxia Wu , Zhiming Wang , Shun Deng , Shutang Zhou
      Juvenile hormone (JH) prevents insect larval metamorphosis and stimulates processes for adult reproduction. Krüppel-homolog 1 (Kr-h1), a zinc finger transcription factor, is shown to mediate the anti-metamorphic effect of JH in both holometabolous and hemimetabolous insects. However, the role of Kr-h1 in JH-mediated reproduction has not been determined. Using the migratory locust, Locusta migratoria, we showed here that Kr-h1 was expressed in response to JH in female adults, and Kr-h1 transcription was directly regulated by the JH-receptor complex comprised of Methoprene-tolerant (Met) and steroid receptor co-activator. We demonstrated that Kr-h1 RNAi phenocopied Met RNAi and JH-deprived condition during post-eclosion development and vitellogenesis of female locusts. Knockdown of Kr-h1 resulted in substantial reduction of Vg expression in the fat body and lipid accumulation in the primary oocytes, accompanied by blocked follicular epithelium development, oocyte maturation and ovarian growth. Our data therefore reveal a crucial role of Kr-h1 in insect vitellogenesis and egg production. This study suggests that JH-Met-Kr-h1 signaling pathway is also functional in insect reproduction.
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      PubDate: 2014-07-26T22:00:00Z
       
  • Characterization of the Rel2-regulated transcriptome and proteome of
           Anopheles stephensi identifies new anti-Plasmodium factors
    • Abstract: Publication date: September 2014
      Source:Insect Biochemistry and Molecular Biology, Volume 52
      Author(s): Andrew Pike , Alekhya Vadlamani , Simone L. Sandiford , Anthony Gacita , George Dimopoulos
      Mosquitoes possess an innate immune system that is capable of limiting infection by a variety of pathogens, including the Plasmodium spp. parasites responsible for human malaria. The Anopheles immune deficiency (IMD) innate immune signaling pathway confers resistance to Plasmodium falciparum. While some previously identified Anopheles anti-Plasmodium effectors are regulated through signaling by Rel2, the transcription factor of the IMD pathway, many components of this defense system remain uncharacterized. To begin to better understand the regulation of immune effector proteins by the IMD pathway, we used oligonucleotide microarrays and iTRAQ to analyze differences in mRNA and protein expression, respectively, between transgenic Anopheles stephensi mosquitoes exhibiting blood meal-inducible overexpression of an active recombinant Rel2 and their wild-type conspecifics. Numerous genes were differentially regulated at both the mRNA and protein levels following induction of Rel2. While multiple immune genes were up-regulated, a majority of the differentially expressed genes have no known immune function in mosquitoes. Selected up-regulated genes from multiple functional categories were tested for both anti-Plasmodium and anti-bacterial action using RNA interference (RNAi). Based on our experimental findings, we conclude that increased expression of the IMD immune pathway-controlled transcription factor Rel2 affects the expression of numerous genes with diverse functions, suggesting a broader physiological impact of immune activation and possible functional versatility of Rel2. Our study has also identified multiple novel genes implicated in anti-Plasmodium defense.
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      PubDate: 2014-07-26T22:00:00Z
       
  • The MEKRE93 (Methoprene tolerant-Krüppel homolog 1-E93) pathway in
           the regulation of insect metamorphosis, and the homology of the pupal
           stage
    • Abstract: Publication date: September 2014
      Source:Insect Biochemistry and Molecular Biology, Volume 52
      Author(s): Xavier Belles , Carolina G. Santos
      Recent studies on transcription factor E93 revealed that it triggers adult morphogenesis in Blattella germanica, Tribolium castaneum and Drosophila melanogaster. Moreover, we show here that Krüppel homolog 1 (Kr-h1), a transducer of the antimetamorphic action of juvenile hormone (JH), represses E93 expression. Kr-h1 is upstream of E93, and upstream of Kr-h1 is Methoprene-tolerant (Met), the latter being the JH receptor in hemimetabolan and holometabolan species. As such, the Met – Kr-h1 – E93 pathway (hereinafter named “MEKRE93 pathway”) appears to be central to the status quo action of JH, which switch adult morphogenesis off and on in species ranging from cockroaches to flies. The decrease in Kr-h1 mRNA and the rise of E93 expression that triggers adult morphogenesis occur at the beginning of the last instar nymph or in the prepupae of hemimetabolan and holometabolan species, respectively. This suggests that the hemimetabolan last nymph (considering the entire stage, from the apolysis to the last instar until the next apolysis that gives rise to the adult) is ontogenetically homologous to the holometabolan pupa (also considered between two apolyses, thus comprising the prepupal stage).
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      PubDate: 2014-07-26T22:00:00Z
       
  • Antennal transcriptome analysis and comparison of olfactory genes in two
           sympatric defoliators, Dendrolimus houi and Dendrolimus kikuchii
           (Lepidoptera: Lasiocampidae)
    • Abstract: Publication date: September 2014
      Source:Insect Biochemistry and Molecular Biology, Volume 52
      Author(s): Sufang Zhang , Zhen Zhang , Hongbin Wang , Xiangbo Kong
      The Yunnan pine and Simao pine caterpillar moths, Dendrolimus houi Lajonquière and Dendrolimus kikuchii Matsumura (Lepidoptera: Lasiocampidae), are two closely related and sympatric pests of coniferous forests in southwestern China, and olfactory communication systems of these two insects have received considerable attention because of their economic importance. However, there is little information on the molecular aspect of odor detection about these insects. Furthermore, although lepidopteran species have been widely used in studies of insect olfaction, few work made comparison between sister moths on the olfactory recognition mechanisms. In this study, next-generation sequencing of the antennal transcriptome of these two moths were performed to identify the major olfactory genes. After comparing the antennal transcriptome of these two moths, we found that they exhibit highly similar transcripts-associated GO terms. Chemosensory gene families were further analyzed in both species. We identified 23 putative odorant binding proteins (OBP), 17 chemosensory proteins (CSP), two sensory neuron membrane proteins (SNMP), 33 odorant receptors (OR), and 10 ionotropic receptors (IR) in D. houi; and 27 putative OBPs, 17 CSPs, two SNMPs, 33 ORs, and nine IRs in D. kikuchii. All these transcripts were full-length or almost full-length. The predicted protein sequences were compared with orthologs in other species of Lepidoptera and model insects, including Bombyx mori, Manduca sexta, Heliothis virescens, Danaus plexippus, Sesamia inferens, Cydia pomonella, and Drosophila melanogaster. The sequence homologies of the orthologous genes in D. houi and D. kikuchii are very high. Furthermore, the olfactory genes were classed according to their expression level, and the highly expressed genes are our target for further function investigation. Interestingly, many highly expressed genes are ortholog gene of D. houi and D. kikuchii. We also found that the Classic OBPs were further separated into three groups according to their motifs, which will help future functional researches. Surprisingly, no pheromone receptor was identified in the two Dendrolimus species, which may indicate a special pheromone identification mechanism in Dendrolimus. Our work allows for further functional studies of pheromones and host volatile recognition genes, and give novel candidate targets for pest management.
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      PubDate: 2014-07-26T22:00:00Z
       
  • CutProtFam-Pred: Detection and classification of putative structural
           cuticular proteins from sequence alone, based on profile Hidden Markov
           Models
    • Abstract: Publication date: September 2014
      Source:Insect Biochemistry and Molecular Biology, Volume 52
      Author(s): Zoi S. Ioannidou , Margarita C. Theodoropoulou , Nikos C. Papandreou , Judith H. Willis , Stavros J. Hamodrakas
      The arthropod cuticle is a composite, bipartite system, made of chitin filaments embedded in a proteinaceous matrix. The physical properties of cuticle are determined by the structure and the interactions of its two major components, cuticular proteins (CPs) and chitin. The proteinaceous matrix consists mainly of structural cuticular proteins. The majority of the structural proteins that have been described to date belong to the CPR family, and they are identified by the conserved R&R region (Rebers and Riddiford Consensus). Two major subfamilies of the CPR family RR-1 and RR-2, have also been identified from conservation at sequence level and some correlation with the cuticle type. Recently, several novel families, also containing characteristic conserved regions, have been described. The package HMMER v3.0 (http://hmmer.janelia.org/) was used to build characteristic profile Hidden Markov Models based on the characteristic regions for 8 of these families, (CPF, CPAP3, CPAP1, CPCFC, CPLCA, CPLCG, CPLCW, Tweedle). In brief, these families can be described as having: CPF (a conserved region with 44 amino acids); CPAP1 and CPAP-3 (analogous to peritrophins, with 1 and 3 chitin-binding domains, respectively); CPCFC (2 or 3 C-x(5)-C repeats); and four of five low complexity (LC) families, each with characteristic domains. Using these models, as well as the models previously created for the two major subfamilies of the CPR family, RR-1 and RR-2 (Karouzou et al., 2007), we developed CutProtFam-Pred, an on-line tool (http://bioinformatics.biol.uoa.gr/CutProtFam-Pred) that allows one to query sequences from proteomes or translated transcriptomes, for the accurate detection and classification of putative structural cuticular proteins. The tool has been applied successfully to diverse arthropod proteomes including a crustacean (Daphnia pulex) and a chelicerate (Tetranychus urticae), but at this taxonomic distance only CPRs and CPAPs were recovered.
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      PubDate: 2014-07-26T22:00:00Z
       
  • Horizontal gene transfer and functional diversification of plant cell wall
           degrading polygalacturonases: Key events in the evolution of herbivory in
           beetles
    • Abstract: Publication date: September 2014
      Source:Insect Biochemistry and Molecular Biology, Volume 52
      Author(s): Roy Kirsch , Lydia Gramzow , Günter Theißen , Blair D. Siegfried , Richard H. ffrench-Constant , David G. Heckel , Yannick Pauchet
      Plant cell walls are the largest reservoir of organic carbon on earth. To breach and utilize this carbohydrate-rich protective barrier, microbes secrete plant cell wall degrading enzymes (PCWDEs) targeting pectin, cellulose and hemicelluloses. There is a growing body of evidence that genomes of some herbivorous insects also encode PCWDEs, raising questions about their evolutionary origins and functions. Among herbivorous beetles, pectin-degrading polygalacturonases (PGs) are found in the diverse superfamilies Chrysomeloidea (leaf beetles, long-horn beetles) and Curculionoidea (weevils). Here our aim was to test whether these arose from a common ancestor of beetles or via horizontal gene transfer (HGT), and whether PGs kept their ancestral function in degrading pectin or evolved novel functions. Transcriptome data derived from 10 beetle species were screened for PG-encoding sequences and used for phylogenetic comparisons with their bacterial, fungal and plant counterparts. These analyses revealed a large family of PG-encoding genes of Chrysomeloidea and Curculionoidea sharing a common ancestor, most similar to PG genes of ascomycete fungi. In addition, 50 PGs from beetle digestive systems were heterologously expressed and functionally characterized, showing a set of lineage-specific consecutively pectin-degrading enzymes, as well as conserved but enzymatically inactive PG proteins. The evidence indicates that a PG gene was horizontally transferred ∼200 million years ago from an ascomycete fungus to a common ancestor of Chrysomeloidea and Curculionoidea. This has been followed by independent duplications in these two lineages, as well as independent replacement in two sublineages of Chrysomeloidea by two other subsequent HGTs. This origin, leading to subsequent functional diversification of the PG gene family within its new hosts, was a key event promoting the evolution of herbivory in these beetles.
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      PubDate: 2014-07-26T22:00:00Z
       
  • Juvenile hormone regulates Aedes aegypti Krüppel homolog 1 through a
           conserved E box motif
    • Abstract: Publication date: September 2014
      Source:Insect Biochemistry and Molecular Biology, Volume 52
      Author(s): Yingjun Cui , Yipeng Sui , Jingjing Xu , Fang Zhu , Subba Reddy Palli
      Juvenile hormone (JH) plays important roles in regulation of many physiological processes including development, reproduction and metabolism in insects. However, the molecular mechanisms of JH signaling pathway are not completely understood. To elucidate the molecular mechanisms of JH regulation of Krüppel homolog 1 gene (Kr-h1) in Aedes aegypti, we employed JH-sensitive Aag-2 cells developed from the embryos of this insect. In Aag-2 cells, AaKr-h1 gene is induced by nanomolar concentration of JH III, its expression peaked at 1.5 h after treatment with JH III. RNAi studies showed that JH induction of this gene requires the presence of Ae. aegypti methoprene-tolerant (AaMet). A conserved 13 nucleotide JH response element (JHRE, TGCCTCCACGTGC) containing canonical E box motif (underlined) identified in the promoter of AaKr-h1 is required for JH induction of this gene. Critical nucleotides in the JHRE required for JH action were identified by employing mutagenesis and reporter assays. Reporter assays also showed that basic helix loop helix (bHLH) domain of AaMet is required for JH induction of AaKr-h1. 5' rapid amplification of cDNA ends method identified two isoforms of AaKr-h1, AaKr-h1α and AaKr-h1β, the expression of both isoforms is induced by JH III, but AaKr-h1α is the predominant isoform in both Aag-2 cells and Ae. aegypti larvae.
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      PubDate: 2014-07-26T22:00:00Z
       
  • β-chain of ATP synthase as a lipophorin binding protein and its role
           in lipid transfer in the midgut of Panstrongylus megistus (Hemiptera:
           Reduviidae)
    • Abstract: Publication date: September 2014
      Source:Insect Biochemistry and Molecular Biology, Volume 52
      Author(s): Leonardo L. Fruttero , Diogo R. Demartini , Edilberto R. Rubiolo , Célia R. Carlini , Lilián E. Canavoso
      Lipophorin, the main lipoprotein in the circulation of the insects, cycles among peripheral tissues to exchange its lipid cargo at the plasma membrane of target cells, without synthesis or degradation of its apolipoprotein matrix. Currently, there are few characterized candidates supporting the functioning of the docking mechanism of lipophorin-mediated lipid transfer. In this work we combined ligand blotting assays and tandem mass spectrometry to characterize proteins with the property to bind lipophorin at the midgut membrane of Panstrongylus megistus, a vector of Chagas' disease. We further evaluated the role of lipophorin binding proteins in the transfer of lipids between the midgut and lipophorin. The β subunit of the ATP synthase complex (β-ATPase) was identified as a lipophorin binding protein. β-ATPase was detected in enriched midgut membrane preparations free of mitochondria. It was shown that β-ATPase partially co-localizes with lipophorin at the plasma membrane of isolated enterocytes and in the sub-epithelial region of the midgut tissue. The interaction of endogenous lipophorin and β-ATPase was also demonstrated by co-immunoprecipitation assays. Blocking of β-ATPase significantly diminished the binding of lipophorin to the isolated enterocytes and to the midgut tissue. In vivo assays injecting the β-ATPase antibody significantly reduced the transfer of [3H]-diacylglycerol from the midgut to the hemolymph in insects fed with [9,10-3H]-oleic acid, supporting the involvement of lipophorin-β-ATPase association in the transfer of lipids. In addition, the β-ATPase antibody partially impaired the transfer of fatty acids from lipophorin to the midgut, a less important route of lipid delivery to this tissue. Taken together, the findings strongly suggest that β-ATPase plays a role as a docking lipophorin receptor at the midgut of P. megistus.
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      PubDate: 2014-07-26T22:00:00Z
       
  • Characterization of a novel Manduca sexta beta-1, 3-glucan recognition
           protein (βGRP3) with multiple functions
    • Abstract: Publication date: September 2014
      Source:Insect Biochemistry and Molecular Biology, Volume 52
      Author(s): Xiang-Jun Rao , Xue Zhong , Xin-Yu Lin , Xiao-Hong Huang , Xiao-Qiang Yu
      Recognition of pathogens by insect pattern recognition receptors is critical to mount effective immune responses. In this study, we reported a new member (βGRP3) of the β-1, 3-glucan recognition protein (βGRP) family from the tobacco hornworm Manduca sexta. Unlike other members of the M. sexta βGRP family proteins, which contain an N-terminal small glucan binding domain and a C-terminal large glucanase-like domain, βGRP3 is 40–45 residues shorter at the N-terminus and lacks the small glucan binding domain. The glucanase-like domain of βGRP3 is most similar to that of M. sexta microbe binding protein (MBP) with 78% identity. βGRP3 transcript was mainly expressed in the fat body, and both its mRNA and protein levels were not induced by microorganisms in larvae. Recombinant βGRP3 purified from Drosophila S2 cells could bind to several Gram-negative and Gram-positive bacteria and yeast, as well as to laminarin (β-1, 3-glucan), mannan, lipopolysaccharide (LPS), lipoteichoic acid (LTA), and meso-diaminopimelic acid (DAP)-type peptidoglycan (PG), but did not bind to Lysine-type PG. Binding of βGRP3 to laminarin could be competed well by free laminarin, mannan, LPS and LTA, but almost not competed by free PGs. Recombinant βGRP3 could agglutinate Bacillus cereus and Escherichia coli in a calcium-dependent manner and showed antibacterial (bacteriostatic) activity against B. cereus, novel functions that have not been reported for the βGRP family proteins before. M. sexta βGRP3 may serve as an immune surveillance receptor with multiple functions.
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      PubDate: 2014-07-26T22:00:00Z
       
  • sHsp22.6, an intronless small heat shock protein gene, is involved in
           stress defence and development in Apis cerana cerana
    • Abstract: Publication date: October 2014
      Source:Insect Biochemistry and Molecular Biology, Volume 53
      Author(s): Yuanying Zhang , Yaling Liu , Xulei Guo , Yalu Li , Hongru Gao , Xingqi Guo , Baohua Xu
      Small heat shock proteins (sHSPs) play an important role in protecting against stress-induced cell damage and fundamental physiological processes. In this study, we identified an intronless sHsp gene from Apis cerana cerana (AccsHsp22.6). The open reading frame of AccsHsp22.6 was 585 bp and encoded a 194 amino acid protein. Furthermore, a 2064 bp 5'-flanking region was isolated, and potential transcription factor binding sites associated with development and stress response were identified. Quantitative PCR and western blot analyses demonstrated that AccsHsp22.6 was detected at higher levels in the midgut than in other tissues tested, and it is highly expressed during the shift to different development stages. Moreover, AccsHsp22.6 was significantly up-regulated by abiotic and biotic stresses, such as 4 °C, 16 °C, 42 °C, cyhalothrin, pyridaben, H2O2, UV, CdCl2, 20-hydroxyecdysone and Ascosphaera apis treatments. However, AccsHsp22.6 was slightly repressed by other stresses, including 25 °C, phoxim, paraquat and HgCl2 treatments. The recombinant AccsHSP22.6 also exhibited significant temperature tolerance, antioxidation and molecular chaperone activity. In addition, we found that knockdown of AccsHsp22.6 by RNA interference remarkably reduced temperature tolerance in A. cerana cerana. Taken together, these results suggest that AccsHsp22.6 plays an essential role in the development stages and defence against cellular stress.
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      PubDate: 2014-07-26T22:00:00Z
       
  • Editorial Board
    • Abstract: Publication date: July 2014
      Source:Insect Biochemistry and Molecular Biology, Volume 50




      PubDate: 2014-06-07T16:05:27Z
       
  • Unexpected functional diversity in the fatty acid desaturases of the flour
           beetle Tribolium castaneum and identification of key residues determining
           activity
    • Abstract: Publication date: Available online 29 May 2014
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Victoria S. Haritos , Irene Horne , Katherine Damcevski , Karen Glover , Nerida Gibb
      Desaturases catalyze modifications to fatty acids which are essential to homeostasis and for pheromone and defensive chemical production. All desaturases of the flour beetle Tribolium castaneum were investigated via query of the sequenced genome which yielded 15 putative acyl-Coenzyme A genes. Eleven desaturase mRNA were obtained in full length and functionally expressed in yeast. Phylogenetic analysis separated the desaturases into 4 distinct clades; one clade contained conserved beetle Δ9 desaturases, second clade was Tribolium-specific having diverse activities including Δ5, Δ9 and Δ12 desaturation and the other 2 clades had mixed insect representatives. Three members of this clade contained unusual inserted sequences of ∼20 residues in the C-terminal region and were related to desaturases that all contained similar inserts. Deletion of the entirety of the insert in the flour beetle Δ12 desaturase abolished its activity but this was partially restored by the reintroduction of two histidine residues, suggesting the histidine(s) are required for activity but the full length insert is not. Five new desaturase activities were discovered: Δ9 desaturation of C12:0-C16:0 substrates; two unprecedented Δ5 enzymes acting on C18:0 and C16:0; Δ9 activity exclusively on C16:0 and a further stearate Δ9 desaturase. qPCR analysis ruled out a role in sex pheromone synthesis for the Δ5 and Δ9/C16:0 desaturases. The flour beetle genome has underpinned an examination of all transcribed desaturases in the organism and revealed a diversity of novel and unusual activities, an improved understanding of the evolutionary relationships among insect desaturases and sequence determinants of activity.
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      PubDate: 2014-06-01T14:46:49Z
       
  • A conserved SUMOylation signaling for cell cycle control in a holocentric
           species Bombyx mori
    • Abstract: Publication date: Available online 28 May 2014
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Zhiqing Li , Hiroaki Mon , Jian Xu , Li Zhu , Jae Man Lee , Takahiro Kusakabe
      SUMOylation is an essential post-translational modification that regulates a variety of cellular processes including cell cycle progression. Although the SUMOylation pathway has been identified and investigated in many eukaryotes, the mechanisms of SUMOylation in regulating the functions of various substrates are still poorly understood. Here, we utilized a model species, the silkworm Bombyx mori that possesses holocentric chromosomes, to exploit the role of the SUMOylation system in cell cycle regulation. We identified all the components that are involved in the SUMOylation pathway in the silkworm genome. Our data revealed a cell cycle-dependent transcription of the SUMOylation genes, localization of the SUMOylation proteins, and abundance of the SUMOylation substrates in cultured silkworm cells. Importantly, the proliferation of the silkworm cells was strikingly inhibited by interference with SUMOylation genes expression, possibly due to an arrest of the SUMOylation-deficient cells at the G2/M phase. Furthermore, disruption of the SUMOylation genes induced the defects of holocentric chromosome congression and segregation during mitosis, which was consistent with high expressions of the SUMOylation genes and high enrichments of global SUMOylation at this stage, suggesting that the SUMOylation system in silkworm is essential for cell cycle regulation, with one particular role in mitosis.
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      PubDate: 2014-06-01T14:46:49Z
       
  • Oleic acid is a precursor of linoleic acid and the male sex pheromone in
           Nasonia vitripennis
    • Abstract: Publication date: Available online 27 May 2014
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Birgit Blaul , Robert Steinbauer , Philipp Merkl , Rainer Merkl , Herbert Tschochner , Joachim Ruther
      Linoleic acid (C18:2Δ9,12, LA) is crucial for many cell functions in organisms. It has long been a paradigm that animals are unable to synthesize LA from oleic acid (C18:1Δ9, OA) because they were thought to miss Δ12-desaturases for inserting a double bound at the Δ12-position. Today it is clear that this is not true for all animals because some insects and other invertebrates have been demonstrated to synthesize LA. However, the ability to synthesize LA is known in only five insect orders and no examples have been reported so far in the Hymenoptera. LA plays a particular role in the parasitic wasp Nasonia vitripennis, because it is the precursor of the male sex pheromone consisting of (4R,5R)- and (4R,5S)-5-hydroxy-4-decanolides. Here we demonstrate by stable isotope labeling that N. vitripennis is able to incorporate externally applied fully 13C-labeled OA into the male sex pheromone suggesting that they convert initially OA into LA. To verify this assumption, we produced fly host (Lucilia caesar) which were experimentally enriched in 13C-labeled OA and reared male parasitoids on these hosts. Chemical analysis of transesterified lipid raw extracts from hosts and parasitoids revealed that N. vitripennis but not L. caesar contained 13C-labeled LA methyl ester. Furthermore, male wasps from the manipulated hosts produced significant amounts of 13C-labeled sex pheromone. These results suggest that N. vitripennis possesses a Δ12-desaturase. The additional fitness relevant function as pheromone precursor might have favored the evolution of LA biosynthesis in N. vitripennis to make the wasps independent of the formerly essential nutrient.
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      PubDate: 2014-06-01T14:46:49Z
       
  • Molecular and functional characterization of Anopheles gambiae inward
           rectifier potassium (Kir1) channels: A novel role in egg production
    • Abstract: Publication date: Available online 20 May 2014
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Rene Raphemot , Tania Y. Estévez-Lao , Matthew F. Rouhier , Peter M. Piermarini , Jerod S. Denton , Julián F. Hillyer
      Inward rectifier potassium (Kir) channels play essential roles in regulating diverse physiological processes. Although Kir channels are encoded in mosquito genomes, their functions remain largely unknown. In this study, we identified the members of the Anopheles gambiae Kir gene family and began to investigate their function. Notably, we sequenced the A. gambiae Kir1 (AgKir1) gene and showed that it encodes all the canonical features of a Kir channel: an ion pore that is composed of a pore helix and a selectivity filter, two transmembrane domains that flank the ion pore, and the so-called G-loop. Heterologous expression of AgKir1 in Xenopus oocytes revealed that this gene encodes a functional, barium-sensitive Kir channel. Quantitative RT-PCR experiments then showed that relative AgKir1 mRNA levels are highest in the pupal stage, and that AgKir1 mRNA is enriched in the adult ovaries. Gene silencing of AgKir1 by RNA interference did not affect the survival of female mosquitoes following a blood meal, but decreased their egg output. These data provide evidence for a new role of Kir channels in mosquito fecundity, and further validates them as promising molecular targets for the development of a new class of mosquitocides to be used in vector control.
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      PubDate: 2014-05-24T19:57:05Z
       
  • The evolution of insecticide resistance in the peach potato aphid, Myzus
           persicae
    • Abstract: Publication date: Available online 20 May 2014
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Chris Bass , Mirel Puinean , Christoph T. Zimmer , Ian Denholm , Linda M. Field , Stephen P. Foster , Oliver Gutbrod , Ralf Nauen , Russell Slater , Martin S. Williamson
      The peach potato aphid, Myzus persicae is a globally distributed crop pest with a host range of over 400 species including many economically important crop plants. The intensive use of insecticides to control this species over many years has led to populations that are now resistant to several classes of insecticide. Work spanning over 40 years has shown that M. persicae has a remarkable ability to evolve mechanisms that avoid or overcome the toxic effect of insecticides with at least seven independent mechanisms of resistance described in this species to date. The array of novel resistance mechanisms, including several ‘first examples’, that have evolved in this species represents an important case study for the evolution of insecticide resistance and also rapid adaptive change in insects more generally. In this review we summarise the biochemical and molecular mechanisms underlying resistance in M. persicae and the insights study of this topic has provided on how resistance evolves, the selectivity of insecticides, and the link between resistance and host plant adaptation.
      Graphical abstract image

      PubDate: 2014-05-24T19:57:05Z
       
  • High resolution genetic mapping uncovers chitin synthase-1 as the
           target-site of the structurally diverse mite growth inhibitors
           clofentezine, hexythiazox and etoxazole in Tetranychus urticae
    • Abstract: Publication date: Available online 22 May 2014
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Peter Demaeght , Edward J. Osborne , Jothini Odman-Naresh , Miodrag Grbić , Ralf Nauen , Hans Merzendorfer , Richard M. Clark , Thomas Van Leeuwen
      The acaricides clofentezine, hexythiazox and etoxazole are commonly referred to as ‘mite growth inhibitors’, and clofentezine and hexythiazox have been used successfully for the integrated control of plant mite pests for decades. Although they are still important today, their mode of action has remained elusive. Recently, a mutation in chitin synthase 1 (CHS1) was linked to etoxazole resistance. In this study, we identified and investigated a T. urticae strain (HexR) harboring recessive, monogenic resistance to each of hexythiazox, clofentezine, and etoxazole. To elucidate if there is a common genetic basis for the observed cross-resistance, we adapted a previously developed bulk segregant analysis method to map with high resolution a single, shared resistance locus for all three compounds. This finding indicates that the underlying molecular basis for resistance to all three compounds is identical. This locus is centered on the CHS1 gene, and as supported by additional genetic and biochemical studies, a non-synonymous variant (I1017F) in CHS1 associates with resistance to each of the tested acaricides in HexR. Our findings thus demonstrate a shared molecular mode of action for the chemically diverse mite growth inhibitors clofentezine, hexythiazox and etoxazole as inhibitors of an essential, non-catalytic activity of CHS1. Given the previously documented cross-resistance between clofentezine, hexythiazox and the benzyolphenylurea compounds flufenoxuron and cycloxuron, CHS1 should be also considered as a potential target-site of insecticidal BPUs.
      Graphical abstract image

      PubDate: 2014-05-24T19:57:05Z
       
  • New insight into the RNA interference response against cathepsin-L gene in
           the pea aphid, Acyrthosiphon pisum: Molting or gut phenotypes specifically
           induced by injection or feeding treatments
    • Abstract: Publication date: Available online 21 May 2014
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Panagiotis Sapountzis , Gabrielle Duport , Séverine Balmand , Karen Gaget , Stéphanie Jaubert-Possamai , Gérard Febvay , Hubert Charles , Yvan Rahbé , Stefano Colella , Federica Calevro
      RNA interference (RNAi) has been widely and successfully used for gene inactivation in insects, including aphids, where dsRNA administration can be performed either by feeding or microinjection. However, several aspects related to the aphid response to RNAi, as well as the influence of the administration method on tissue response, or the mixed success to observe phenotypes specific to the gene targeted, are still unclear in this insect group. In the present study, we made the first direct comparison of two administration methods (injection or feeding) for delivery of dsRNA targeting the cathepsin-L gene in the pea aphid, Acyrthosiphon pisum. In order to maximize the possibility of discovering specific phenotypes, the effect of the treatment was analyzed in single individual aphids at the level of five body compartments: the bacteriocytes, the gut, the embryonic chains, the head and the remaining body carcass. Our analysis revealed that gene expression knockdown effect in each single body compartment was dependent on the administration method used, and allowed us to discover new functions for the cathepsin-L gene in aphids. Injection of cathepsin-L dsRNA was much more effective on carcass and head, inducing body morphology alterations, and suggesting a novel role of this gene in the molting of these insects. Administration by feeding provoked cathepsin-L knockdown in the gut and specific gut epithelial cell alteration, therefore allowing a better characterization of tissue specific role of this gene in aphids.
      Graphical abstract image

      PubDate: 2014-05-24T19:57:05Z
       
  • Metabolic Analysis Reveals Changes in the Mevalonate and Juvenile Hormone
           Synthesis Pathways Linked to the Mosquito Reproductive Physiology
    • Abstract: Publication date: Available online 14 May 2014
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Crisalejandra Rivera-Perez , Marcela Nouzova , Ivanna Lamboglia , Fernando G. Noriega
      Juvenile hormone (JH) regulates reproductive maturation in insects; therefore interruption of JH biosynthesis has been considered as a strategy for the development of target-specific insecticides. The corpora allata (CA) from mosquitoes is highly specialized to supply variable levels of JH, which are linked to ovarian developmental stages and influenced by nutritional signals. However, very little is known about how changes in JH synthesis relate to reproductive physiology and how JH synthesis regulation is translated into changes in the CA machinery. With the advent of new methods that facilitate the analysis of transcripts, enzymes and metabolites in the minuscule CA, we were able to provide comprehensive descriptions of the mevalonic (MVA) and JH synthesis pathways by integrating information on changes in the basic components of those pathways. Our results revealed remarkable dynamic changes in JH synthesis and exposed part of a complex mechanism that regulates CA activity. Principal component (PC) analyses validated that both pathways (MVAP and JH-branch) are transcriptionally co-regulated as a single unit, and catalytic activities for the enzymes of the MVAP and JH-branch also changed in a coordinate fashion. Metabolite studies showed that global fluctuations in the intermediate pool sizes in the MVAP and JH-branch were often inversely related. PC analyses suggest that in female mosquitoes, there are at least 4 developmental switches that alter JH synthesis by modulating the flux at distinctive points in both pathways.
      Graphical abstract image

      PubDate: 2014-05-15T09:20:42Z
       
  • Exoskeleton formation in Apis mellifera: cuticular hydrocarbons profiles
           and expression of desaturase and elongase genes during pupal and adult
           development
    • Abstract: Publication date: Available online 6 May 2014
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Tiago Falcón , Maria Juliana Ferreira-Caliman , Francis Morais Franco Nunes , Érica Donato Tanaka , Fábio Santos do Nascimento , Márcia Maria Gentile Bitondi
      Cuticular hydrocarbons (CHCs) are abundant in the superficial cuticular layer (envelope) of insects where they play roles as structural, anti-desiccation and semiochemical compounds. Many studies have investigated the CHC composition in the adult insects. However, studies on the profiles of these compounds during cuticle formation and differentiation are scarce and restrict to specific stages of a few insect species. We characterized the CHCs developmental profiles in the honeybee workers during an entire molting cycle (from pupal-to-adult ecdyses) and in mature adults (forager bees). Gas chromatography/mass spectrometry (GC/MS) analysis revealed remarkable differences in the relative quantities of CHCs, thus discriminating pupae, developing and newly-ecdysed adults, and foragers from each other. In parallel, the honeybee genome database was searched for predicted gene models using known amino acid sequences of insect enzymes catalyzing lipid desaturation (desaturases) or elongation (elongases) as queries in BLASTP analysis. The expression levels of six desaturase genes and ten elongase genes potentially involved in CHC biosynthesis were determined by reverse transcription and real time polymerase chain reaction (RT-qPCR) in the developing integument (cuticle and subjacent epidermis). Aiming to predict roles for these genes in CHC biosynthesis, the developmental profiles of CHCs and desaturase/elongase transcript levels were evaluated using Spearman correlation coefficient. This analysis pointed to differential roles for these gene products in the biosynthesis of certain CHC classes. Based on the assumption that homologous proteins may share a similar function, phylogenetic trees were reconstructed as an additional strategy to predict functions and evolutionary relationships of the honeybee desaturases and elongases. Together, these approaches highlighted the molecular complexity underlying the formation of the lesser known layer of the cuticular exoskeleton, the envelope.
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      PubDate: 2014-05-09T23:38:42Z
       
  • Editorial Board
    • Abstract: Publication date: June 2014
      Source:Insect Biochemistry and Molecular Biology, Volume 49




      PubDate: 2014-05-05T09:05:05Z
       
  • Manduca sexta proprophenoloxidase activating proteinase-3 (PAP3)
           stimulates melanization by activating proPAP3, proSPHs, and proPOs
    • Abstract: Publication date: Available online 24 April 2014
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Yang Wang , Zhiqiang Lu , Haobo Jiang
      Melanization participates in various insect physiological processes including antimicrobial immune responses. Phenoloxidase (PO), a critical component of the enzyme system catalyzing melanin formation, is produced as an inactive precursor prophenoloxidase (proPO) and becomes active via specific proteolytic cleavage by proPO activating proteinase (PAP). In Manduca sexta, three PAPs can activate proPOs in the presence of two serine proteinase homologs (SPH1 and SPH2). While the hemolymph proteinases (HPs) that generate the active PAPs are known, it is unclear how the proSPHs (especially proSPH1) are activated. In this study, we isolated from plasma of bar-stage M. sexta larvae an Ile-Glu-Ala-Arg-p-nitroanilide hydrolyzing enzyme that cleaved the proSPHs. This proteinase, PAP3, generated active SPH1 and SPH2, which function as cofactors for PAP3 in proPO activation. Cleavage of the purified recombinant proSPHs by PAP3 yielded 38 kDa bands similar in mobility to the SPHs formed in vivo. Surprisingly, PAP3 also can activate proPAP3 to stimulate melanization in a direct positive feedback loop. The enhanced proPO activation concurred with the cleavage activation of proHP6, proHP8, proPAP1, proPAP3, proSPH1, proSPH2, proPOs, but not proHP14 or proHP21. These results indicate that PAP3, like PAP1, is a key factor of the self-reinforcing mechanism in the proPO activation system, which is linked to other immune responses in M. sexta.
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      PubDate: 2014-04-24T11:45:23Z
       
  • Non conserved residues between Cqm1 and Aam1 mosquito α-glucosidases
           are critical for the capacity of Cqm1 to bind the Binary (Bin) toxin from
           Lysinibacillus sphaericus
    • Abstract: Publication date: Available online 16 April 2014
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Lígia Maria Ferreira , Tatiany Patrícia Romão , Nathaly Alexandre do Nascimento , Maria da Conceição Mendes Ferreira da Costa , Antônio Mauro Rezende , Osvaldo Pompílio de-Melo-Neto , Maria Helena Neves Lobo Silva-Filha
      The Binary (Bin) toxin from the entomopathogenic bacterium Lysinibacillus sphaericus acts on larvae of the culicid Culex quinquefasciatus through its binding to Cqm1, a midgut-bound α-glucosidase. Specific binding by the BinB subunit to the Cqm1 receptor is essential for toxicity however the toxin is unable to bind to the Cqm1 ortholog from the refractory species Aedes aegypti (Aam1). Here, to investigate the molecular basis for the interaction between Cqm1 and BinB, recombinant Cqm1 and Aam1 were first expressed as soluble forms in Sf9 cells. The two proteins were found to display the same glycosilation patterns and BinB binding properties as the native α-glucosidases. Chimeric constructs were then generated through the exchange of reciprocal fragments between the corresponding Cqm1 and Aam1 cDNAs. Subsequent expression and binding experiments defined a Cqm1 segment encompassing residues S129 and A312 as critical for the interaction with BinB. Through site directed mutagenesis experiments, replacing specific sets of residues from Cqm1 with those of Aam1, the 158GG160 doublet was required for this interaction. Molecular modeling mapped these residues to an exposed loop within the Cqm1’s structure, compatible with a target site for BinB and providing a possible explanation for its lack of binding to Aam1.
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      PubDate: 2014-04-20T08:50:55Z
       
  • Identification of uncoupling protein 4 from the blood-sucking insect
           Rhodnius prolixus and its possible role on protection against oxidative
           stress
    • Abstract: Publication date: Available online 16 April 2014
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Michele Alves-Bezerra , Daniela Cosentino-Gomes , Lisvane P. Vieira , Nathália Rocco-Machado , Katia C. Gondim , José R. Meyer-Fernandes
      Uncoupling proteins (UCPs) play a critical role in the control of the mitochondrial membrane potential (ΔΨm) due to their ability to dissipate the proton gradient, which results in the uncoupling of mitochondrial respiration from ATP production. Most reactive oxygen species generation in mitochondria occurs in complex III, due to an increase of semiquinone (Q −) half-life. When active, UCPs can account as a potential antioxidant system by decreasing ΔΨm and increasing mitochondrial respiration, thus reducing Q − life time. The hematophagous insect Rhodnius prolixus, a vector of Chagas disease, is exposed to a huge increase in oxidative stress after a blood meal because of the hydrolysis of hemoglobin and the release of the cytotoxic heme molecule. Although some protective mechanisms were already described for this insect and other hematophagous arthropods, the putative role of UCP proteins as antioxidants in this context has not been explored. In this report, two genes encoding UCP proteins (RpUcp4 and RpUcp5) were identified in the R. prolixus genome. RpUcp4 is the predominant transcript in most analyzed organs, and both mRNA and protein expression are upregulated (13- and 3-fold increase, respectively) in enterocytes the first day after the blood feeding. The increase in UCP4 expression is coincident with the decrease in hydrogen peroxide (H2O2) generation by midgut cells. Furthermore, in mitochondria isolated from enterocytes, the modulation of UCP activity by palmitic acid and GDP resulted in altered ΔΨm, as well as modulation of H2O2 generation rates. These results indicate that R. prolixus UCP4 may function in an antioxidation mechanism to protect the midgut cells against oxidative damage caused by blood digestion.
      Graphical abstract image

      PubDate: 2014-04-20T08:50:55Z
       
  • Functional analysis of the glycogen binding subunit CG9238/Gbs-70E of
           protein phosphatase 1 in Drosophila melanogaster
    • Abstract: Publication date: Available online 12 April 2014
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Éva Kerekes , Endre Kókai , Ferenc Sándor Páldy , Viktor Dombrádi
      The product of the CG9238 gene that we termed glycogen binding subunit 70E (Gbs-70E) was characterized by biochemical and molecular genetics methods. The interaction between Gbs-70E and all catalytic subunits of protein phosphatase 1 (Pp1-87B, Pp1-9C, Pp1-96A and Pp1-13C) of Drosophila melanogaster was confirmed by pairwise yeast two-hybrid tests, co-immunoprecipitation and pull down experiments. The binding of Gbs-70E to glycogen was demonstrated by sedimentation analysis. With RT-PCR we found that the mRNAs coding for the longer Gbs-70E PB/PC protein was expressed in all developmental stages of the fruit flies while the mRNA for the shorter Gbs-70E PA was restricted to the eggs and the ovaries of the adult females. The development specific expression of the shorter splice variant was not conserved in different Drosophila species. The expression level of the gene was manipulated by P-element insertions and gene deletion to analyze the functions of the gene product. A small or moderate reduction in the gene expression resulted in no significant changes, however, a deletion mutant expressing very low level of the transcript lived shorter and exhibited reduced glycogen content in the imagos. In addition, the gene deletion decreased the fertility of the fruit flies. Our results prove that Gbs-70E functions as the glycogen binding subunit of protein phosphatase 1 that regulates glycogen content and plays a role in the development of eggs in D. melanogaster.
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      PubDate: 2014-04-16T04:14:08Z
       
  • Bacterial origin of a diverse family of UDP-glycosyltransferase genes in
           the Tetranychus urticae genome
    • Abstract: Publication date: Available online 12 April 2014
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Seung-Joon Ahn , Wannes Dermauw , Nicky Wybouw , David G. Heckel , Thomas Van Leeuwen
      UDP-glycosyltransferases (UGTs) catalyze the conjugation of a variety of small lipophilic molecules with uridine diphosphate (UDP) sugars, altering them into more water-soluble metabolites. Thereby, UGTs play an important role in the detoxification of xenobiotics and in the regulation of endobiotics. Recently, the genome sequence was reported for the two-spotted spider mite, Tetranychus urticae, a polyphagous herbivore damaging a number of agricultural crops. Although various gene families implicated in xenobiotic metabolism have been documented in T. urticae, UGTs so far have not. We identified 80 UGT genes in the T. urticae genome, the largest number of UGT genes in a metazoan species reported so far. Phylogenetic analysis revealed that lineage-specific gene expansions increased the diversity of the T. urticae UGT repertoire. Genomic distribution, intron-exon structure and structural motifs in the T. urticae UGTs were also described. In addition, expression profiling after host-plant shifts and in acaricide resistant lines supported an important role for UGT genes in xenobiotic metabolism. Expanded searches of UGTs in other arachnid species (Subphylum Chelicerata), including a spider, a scorpion, two ticks and two predatory mites, unexpectedly revealed the complete absence of UGT genes. However, a centipede (Subphylum Myriapoda) and a water flea and a crayfish (Subphylum Crustacea) contain UGT genes in their genomes similar to insect UGTs, suggesting that the UGT gene family might have been lost early in the Chelicerata lineage and subsequently re-gained in the tetranychid mites. Sequence similarity of T. urticae UGTs and bacterial UGTs and their phylogenetic reconstruction suggest that spider mites acquired UGT genes from bacteria by horizontal gene transfer. Our findings show a unique evolutionary history of the T. urticae UGT gene family among other arthropods and provide important clues to its functions in relation to detoxification and thereby host adaptation.
      Graphical abstract image

      PubDate: 2014-04-16T04:14:08Z
       
  • Postintegration stability of the silkworm piggyBac transposon
    • Abstract: Publication date: Available online 13 April 2014
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Liang Jiang , Qiang Sun , Weiqiang Liu , Huizhen Guo , Zhengwen Peng , Yinghui Dang , Chunlin Huang , Ping Zhao , Qingyou Xia
      The piggyBac transposon is the most widely used vector for generating transgenic silkworms. The silkworm genome contains multiple piggyBac-like sequences that might influence the genetic stability of transgenic lines. To investigate the postintegration stability of piggyBac in silkworms, we used random insertion of the piggyBac [3×p3 EGFP afm] vector to generate a W chromosome-linked transgenic silkworm, named W-T. Results of Southern blot and inverse PCR revealed the insertion of a single copy in the W chromosome of W-T at a standard TTAA insertion site. Investigation of 11 successive generations showed that all W-T females were EGFP positive and all males were EGFP negative; PCR revealed that the insertion site was unchanged in W-T offspring. These results suggested that endogenous piggyBac-like elements did not affect the stability of piggyBac inserted into the silkworm genome.


      PubDate: 2014-04-16T04:14:08Z
       
  • Host plant-specific remodeling of midgut physiology in the generalist
           insect herbivore Trichoplusia ni
    • Abstract: Publication date: Available online 12 April 2014
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Marco Herde , Gregg A. Howe
      Species diversity in terrestrial ecosystems is influenced by plant defense compounds that alter the behavior, physiology, and host preference of insect herbivores. Although it is established that insects evolved the ability to detoxify specific allelochemicals, the mechanisms by which polyphagous insects cope with toxic compounds in diverse host plants are not well understood. Here, we used defended and non-defended plant genotypes to study how variation in chemical defense affects midgut responses of the lepidopteran herbivore Trichoplusia ni, which is a pest of a wide variety of native and cultivated plants. The genome-wide midgut transcriptional response of T. ni larvae to glucosinolate-based defenses in the crucifer Arabidopsis thaliana was characterized by strong induction of genes encoding Phase I and II detoxification enzymes. In contrast, the response of T. ni to proteinase inhibitors and other jasmonate-regulated defenses in tomato (Solanum lycopersicum) was dominated by changes in the expression of digestive enzymes and, strikingly, concomitant repression of transcripts encoding detoxification enzymes. Unbiased proteomic analyses of T. ni feces demonstrated that tomato defenses remodel the complement of T.ni digestive enzymes, which was associated with increased amounts of serine proteases and decreased lipase protein abundance upon encountering tomato defense chemistry. These collective results indicate that T. ni adjusts its gut physiology to the presence of host plant-specific chemical defenses, and further suggest that plants may exploit this digestive flexibility as a defensive strategy to suppress the production of enzymes that detoxify allelochemicals.
      Graphical abstract image

      PubDate: 2014-04-16T04:14:08Z
       
  • Wolbachia-Induced Paternal Defect in Drosophila is likely by Interaction
           with the Juvenile Hormone Pathway
    • Abstract: Publication date: Available online 8 April 2014
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Chen Liu , Jia-Lin Wang , Ya Zheng , En-Juan Xiong , Jing-Jing Li , Lin-Ling Yuan , Xiao-Qiang Yu , Yu-Feng Wang
      Wolbachia are endosymbionts that infect many insect species. They can manipulate the host’s reproduction to increase their own maternal transmission. Cytoplasmic incompatibility (CI) is one such manipulation, which is expressed as embryonic lethality when Wolbachia-infected males mate with uninfected females. However, matings between males and females carrying the same Wolbachia strain result in viable progeny. The molecular mechanisms of CI are currently not clear. We have previously reported that the gene Juvenile hormone-inducible protein 26 (JhI-26) exhibited the highest upregulation in the 3rd instar larval testes of Drosophila melanogaster when infected by Wolbachia. This is reminiscent of an interaction between Wolbachia and juvenile hormone (JH) pathway in flies. Considering that Jhamt gene encodes JH acid methyltransferase, a key regulatory enzyme of JH biosynthesis, and that methoprene-tolerant (Met) has been regarded as the best JH receptor candidate, we first compared the expression of Jhamt and Met between Wolbachia-infected and uninfected fly testes to investigate whether Wolbachia infection influence the JH signaling pathway. We found that the expressions of Jhamt and Met were significantly increased in the presence of Wolbachia, suggesting an interaction of Wolbachia with the JH signaling pathway. Then, we found that overexpression of JhI-26 in Wolbachia-free transgenic male flies caused paternal-effect lethality that mimics the defects associated with CI. JhI-26 overexpressing males resulted in significantly decrease in hatch rate. Surprisingly, Wolbachia-infected females could rescue the egg hatch. In addition, we showed that overexpression of JhI-26 caused upregulation of the male accessory gland protein (Acp) gene CG10433, but not vice versa. This result suggests that JhI-26 may function at the upstream of CG10433. Likewise, overexpression of CG10433 also resulted in paternal-effect lethality. Both JhI-26 and CG10433 overexpressing males resulted in nuclear division defects in the early embryos. Finally, we found that Wolbachia-infected males decreased the propensity of the mated females to remating, a phenotype also caused by both JhI-26 and CG10433 overexpressing males. Taken together, our results provide a working hypothesis whereby Wolbachia induce paternal defects in Drosophila probably by interaction with the JH pathway via JH response genes JhI-26 and CG10433.
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      PubDate: 2014-04-11T02:14:26Z
       
  • bmnpv-miR-3 facilitates BmNPV infection by modulating the expression of
           viral P6.9 and other late genes in Bombyx mori
    • Abstract: Publication date: Available online 1 April 2014
      Source:Insect Biochemistry and Molecular Biology
      Author(s): C.P. Singh , J. Singh , J. Nagaraju
      During the last decade, microRNAs (miRNAs) have emerged as fine tuners of gene expression in various biological processes including host-pathogen interactions. Apart from the role of host encoded miRNAs in host-virus interactions, recent studies have also indicated the key role of virus-encoded miRNAs in the regulation of host defense responses. In the present study, we show that bmnpv-miR-3, a Bombyx mori nucleopolyhedrovirus (BmNPV) encoded miRNA, regulates the expression of DNA binding protein (P6.9) and other late genes, vital for the late stage of viral infection in the host, Bombyx mori. We have performed both cell culture and in vivo experiments to establish the role of bmnpv-miR-3 in the infection cycle of BmNPV. Our findings showed that bmnpv-miR-3 expresses during early stage of infection, and negatively regulates the expression of P6.9. There was an upregulation in P6.9 expression upon blocking of bmnpv-miR-3 by Locked Nucleic Acid (LNA), whereas overexpression of bmnpv-miR-3 resulted in a decreased expression of P6.9. Besides, a remarkable enhancement and reduction in the viral loads were observed upon blocking and overexpression of bmnpv-miR-3, respectively. Furthermore, we have also assessed the host immune response using one of the Lepidoptera-specific antimicrobial proteins, Gloverin-1 upon blocking and overexpression of bmnpv-miR-3, which correlated viral load with the host immune response. All these results together; clearly imply that bmnpv-miR-3-mediated controlled regulation of BmNPV late genes in the early stage of infection helps BmNPV to escape the early immune response from the host.
      Graphical abstract image

      PubDate: 2014-04-06T00:13:08Z
       
  • Molecular Biology of Insect Sodium Channels and Pyrethroid Resistance
    • Abstract: Publication date: Available online 3 April 2014
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Ke Dong , Yuzhe Du , Frank Rinkevich , Yoshiko Nomura , Peng Xu , Lingxin Wang , Kristopher Silver , Boris S. Zhorov
      Voltage-gated sodium channels are essential for the initiation and propagation of the action potential in neurons and other excitable cells. Because of their critical roles in electrical signaling, sodium channels are targets of a variety of naturally occurring and synthetic neurotoxins, including several classes of insecticides. This review is intended to provide an update on the molecular biology of insect sodium channels and the molecular mechanism of pyrethroid resistance. Although mammalian and insect sodium channels share fundamental topological and functional properties, most insect species carry only one sodium channel gene, compared to multiple sodium channel genes found in each mammalian species. Recent studies showed that two posttranscriptional mechanisms, alternative splicing and RNA editing, are involved in generating functional diversity of sodium channels in insects. More than 50 sodium channel mutations have been identified to be responsible for or associated with knockdown resistance (kdr) to pyrethroids in various arthropod pests and disease vectors. Elucidation of molecular mechanism of kdr led to the identification of dual receptor sites of pyrethroids on insect sodium channels. Most of the kdr mutations appear to be located within or close to the two receptor sites. The accumulating knowledge of insect sodium channels and their interactions with insecticides provides a foundation for understanding the neurophysiology of sodium channels in vivo and the development of new and safer insecticides for effective control of arthropod pests and human disease vectors.
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      PubDate: 2014-04-06T00:13:08Z
       
  • Highly Efficient Multiplex Targeted Mutagenesis and Genomic Structure
           Variation in Bombyx mori Cells Using CRISPR/Cas9
    • Abstract: Publication date: Available online 31 March 2014
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Yuanyuan Liu , Sanyuan Ma , Xiaogang Wang , Jiasong Chang , Jie Gao , Run Shi , Jianduo Zhang , Wei Lu , Yue Liu , Ping Zhao , Qingyou Xia
      Bombyx mori is an economically important insect and a model organism for studying lepidopteran and arthropod biology. Using a highly efficient CRISPR/Cas9 system, we showed that this system could mediate highly efficient targeted genome editing of a single gene locus, large chromosomal deletion or inversion, and also multiplex genome editing of 6 genes simultaneously in BmNs cell line derived from B. mori. The simplicity and high efficiency of our system provide unprecedented possibilities for researchers to implement precise and sophisticated manipulation of a chosen B. mori gene in BmNs cells easily in a limited time course, and perhaps new opportunities for functional genomics of B. mori and other lepidopteran insects.
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      PubDate: 2014-03-31T20:20:00Z
       
  • Two essential peritrophic matrix proteins mediate matrix barrier functions
           in the insect midgut
    • Abstract: Publication date: Available online 26 March 2014
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Sinu Agrawal , Marco Kelkenberg , Khurshida Begum , Steinfeld Lea , Clay E. Williams , Karl J. Kramer , Richard W. Beeman , Yoonseong Park , Subbaratnam Muthukrishnan , Hans Merzendorfer
      The peritrophic matrix (PM) in the midgut of insects consists primarily of chitin and proteins and is thought to support digestion and provide protection from abrasive food particles and enteric pathogens. We examined the physiological roles of 11 putative peritrophic matrix protein (PMP) genes of the red flour beetle, Tribolium castaneum (TcPMPs). TcPMP genes are differentially expressed along the length of the midgut epithelium of feeding larvae. RNAi of individual PMP genes revealed no abnormal developmental phenotypes for 9 of the 11 TcPMPs. However, RNAi for two PMP genes, TcPMP3 and TcPMP5-B, resulted in depletion of the fat body, growth arrest, molting defects and mortality. In situ permeability assays after oral administration of different-sized FITC-dextran beads demonstrated that the exclusion size of the larval peritrophic matrix (PM) decreases progressively from >2 MDa to <4 kDa from the anterior to the most posterior regions of the midgut. In the median midguts of control larvae, 2 MDa dextrans were completely retained within the PM lumen, whereas after RNAi for TcPMP3 and TcPMP5-B, these dextrans penetrated the epithelium of the median midgut, indicating loss of structural integrity and barrier function of the larval PM. In contrast, RNAi for TcPMP5-B, but not RNAi for TcPMP3, resulted in breakdown of impermeability to 4 and 40 kDa dextrans in the PM of the posterior midgut. These results suggest that specific PMPs are involved in the regulation of PM permeability, and that a gradient of barrier function is essential for survival and fat body maintenance.
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      PubDate: 2014-03-31T20:20:00Z
       
  • A Major Facilitator Superfamily protein encoded by TcMucK gene is not
           required for cuticle pigmentation, growth and development in Tribolium
           castaneum
    • Abstract: Publication date: Available online 28 March 2014
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Seulgi Mun , Mi Young Noh , Mizuko Osanai-Futahashi , Subbaratnam Muthukrishnan , Karl J. Kramer , Yasuyuki Arakane
      Insect cuticle pigmentation and sclerotization (tanning) are vital physiological processes for insect growth, development and survival. We have previously identified several colorless precursor molecules as well as enzymes involved in their biosynthesis and processing to yield the mature intensely colored body cuticle pigments. A recent study indicated that the Bombyx mori (silkmoth) gene, BmMucK, which encodes a protein orthologous to a Culex pipiens quiquefasciatus (Southern house mosquito) cis,cis, muconate transporter, is a member of the “Major Facilitator Superfamily” (MFS) of transporter proteins and is associated with the appearance of pigmented body segments of naturally occurring body color mutants of B. mori. While RNA interference of the BmMucK gene failed to result in any observable phenotype, RNAi using a dsRNA for an orthologous gene from the red flour beetle, Tribolium castaneum, was reported to result in molting defects and darkening of the cuticle and some body parts, leading to the suggestion that orthologs of MucK genes may differ in their functions among insects. To verify the role and essentiality of the ortholog of this gene in development and body pigmentation function in T. castaneum we obtained cDNAs for the orthologous gene (TcMucK) from RNA isolated from the GA-1 wild-type strain of T. castaneum. The sequence of a 1524 nucleotides-long cDNA for TcMucK which encodes the putatively full-length protein, was assembled from two overlapping RT-PCR fragments and the expression profile of this gene during development was analyzed by real-time PCR. This cDNA encodes a 55.8 kDa protein consisting of 507 amino acid residues and includes 11 putative transmembrane segments. Transcripts of TcMucK were detected throughout all of the developmental stages analyzed. The function of this gene was explored by injection of two different double-stranded RNAs targeting different regions of the TcMucK gene (dsTcMucKs) into young larvae to down-regulate transcripts during subsequent stages of insect development until the adult stage. RNA interference of TcMucK had no observable effects on larval, pupal or adult pigmentation. In addition, it did not affect larval-larval, larval-pupal and pupal-adult molting or survival. Thus, in contrast to the results of Zhao et al. (2012), our study demonstrates that TcMucK is not essential for growth, development or cuticle pigmentation of T. castaneum.
      Graphical abstract image

      PubDate: 2014-03-31T20:20:00Z
       
  • Insulin receptor-mediated nutritional signalling regulates juvenile
           hormone biosynthesis and vitellogenin production in the German cockroach
    • Abstract: Publication date: Available online 21 March 2014
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Marc Abrisqueta , Songül Süren-Castillo , José L. Maestro
      Female reproductive processes, which comprise, amongst others, the synthesis of yolk proteins and the endocrine mechanisms which regulate this synthesis, need a considerable amount of energy and resources. The role of communicating that the required nutritional status has been attained is carried out by nutritional signalling pathways and, in particular, by the insulin receptor (InR) pathway. In the present study, using the German cockroach, Blattella germanica, as a model, we analysed the role of InR in different processes, but mainly those related to juvenile hormone (JH) synthesis and vitellogenin production. We first cloned the InR cDNA from B. germanica (BgInR) and then determined that its expression levels were constant in corpora allata and fat body during the first female gonadotrophic cycle. Results showed that the observed increase in BgInR mRNA in fat body from starved compared to fed females was abolished in those females treated with systemic RNAi in vivo against the transcription factor BgFoxO. RNAi-mediated BgInR knockdown during the final two nymphal stages produced significant delays in the moults, together with smaller adult females which could not spread the fore- and hindwings properly. In addition, BgInR knockdown led to a severe inhibition of juvenile hormone synthesis in adult female corpora allata, with a concomitant reduction of mRNA levels corresponding to 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) synthase-1, HMG-CoA synthase-2, HMG-CoA reductase and methyl farnesoate epoxidase. BgInR RNAi treatment also reduced fat body vitellogenin mRNA and oocyte growth. Our results show that BgInR knockdown produces similar phenotypes to those obtained in starved females in terms of corpora allata activity and vitellogenin synthesis, and indicate that the InR pathway mediates the activation of JH biosynthesis and vitellogenin production elicited by nutrition signalling.
      Graphical abstract image

      PubDate: 2014-03-22T01:14:10Z
       
  • Identification and characterization of plant cell wall degrading enzymes
           from three glycoside hydrolase families in the cerambycid beetle Apriona
           japonica
    • Abstract: Publication date: Available online 21 March 2014
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Yannick Pauchet , Roy Kirsch , Sandra Giraud , Heiko Vogel , David G. Heckel
      Xylophagous insects have evolved to thrive in a highly challenging environment. For example, wood-boring beetles from the family Cerambycidae feed exclusively on woody tissues, and to efficiently access the nutrients present in this sub-optimal environment, they have to cope with the lignocellulose barrier. Whereas microbes of the insect’s gut flora were hypothesized to be responsible for the degradation of lignin, the beetle itself depends heavily on the secretion of a range of enzymes, known as plant cell wall degrading enzymes (PCWDEs), to efficiently digest both hemicellulose and cellulose networks. Here we sequenced the larval gut transcriptome of the Mulberry longhorn beetle, Apriona japonica (Cerambycidae, Lamiinae), in order to investigate the arsenal of putative PCWDEs secreted by this species. We combined our transcriptome with all available sequencing data derived from other cerambycid beetles in order to analyze and get insight into the evolutionary history of the corresponding gene families. Finally, we heterologously expressed and functionally characterized the A. japonica PCWDEs we identified from the transcriptome. Together with a range of endo-β-1,4-glucanases, we describe here for the first time the presence in a species of Cerambycidae of (i) a xylanase member of the subfamily 2 of glycoside hydrolase family 5 (GH5 subfamily 2), as well as (ii) an exopolygalacturonase from family GH28. Our analyses greatly contribute to a better understanding of the digestion physiology of this important group of insects, many of which are major pests of forestry worldwide.
      Graphical abstract image

      PubDate: 2014-03-22T01:14:10Z
       
 
 
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