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  Subjects -> BIOLOGY (Total: 2575 journals)
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BIOCHEMISTRY (190 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: 230)
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: 5)
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: 9)
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: 125)
American Journal of Biochemistry and Molecular Biology     Open Access   (Followers: 11)
Amino Acids     Hybrid Journal   (Followers: 7)
Analytical Biochemistry     Hybrid Journal   (Followers: 157)
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: 9)
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)
Biochemical Genetics     Hybrid Journal   (Followers: 2)
Biochemical Journal     Full-text available via subscription   (Followers: 14)
Biochemical Pharmacology     Hybrid Journal   (Followers: 6)
Biochemical Society Transactions     Full-text available via subscription   (Followers: 2)
Biochemical Systematics and Ecology     Hybrid Journal   (Followers: 3)
Biochemistry     Full-text available via subscription   (Followers: 163)
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: 8)
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: 16)
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  
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: 18)
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 Biology & Drug Design     Hybrid Journal   (Followers: 23)
Chemical Engineering Journal     Hybrid Journal   (Followers: 16)
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: 13)
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  
FEBS Letters     Hybrid Journal   (Followers: 24)

        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]
  • 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.
      Graphical abstract image

      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.
      Graphical abstract image

      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.
      Graphical abstract image

      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.
      Graphical abstract image

      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.
      Graphical abstract image

      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.
      Graphical abstract image

      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.
      Graphical abstract image

      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.
      Graphical abstract image

      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
       
  • Transcriptional Regulation of De Novo Biosynthesis of Cyanogenic
           Glucosides throughout the Life-Cycle of the Burnet Moth Zygaena
           filipendulae (Lepidoptera)
    • Abstract: Publication date: Available online 12 April 2014
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Joel Fürstenberg-Hägg , Mika Zagrobelny , Carl Erik Olsen , Kirsten Jørgensen , Birger Lindberg Møller , Søren Bak
      The six-spotted burnet moth Zygaena filipendulae (Lepidoptera) utilize the two cyanogenic glucosides (CNglcs) linamarin and lotaustralin as deterrents against predators throughout the entire life cycle. CNglcs can be hydrolyzed and bioactivated by β-glucosidases, resulting in the release of toxic hydrogen cyanide. CNglcs are retained through metamorphosis, probably involved in mating communication, and transferred during mating from the male to the female as a nuptial gift. CNglcs can be biosynthesized de novo by Z. filipendulae larvae, but may also be sequestered from their food plant Lotus corniculatus (Fabaceae). These two strategies are tightly linked and adjusted according to the CNglc content and composition of the food plant in order to balance CNglc homeostasis in the larva. In this study, the amounts of CNglcs and transcript levels of the biosynthetic genes were monitored in all life-stages and tissues of Z. filipendulae. During pupation, transcription of the biosynthetic genes is turned off and the CNglc content slowly declines. In females but not males, transcription of the biosynthetic genes is re-activated at the end of pupation. Eggs and embryos do not biosynthesize CNglcs de novo, but are endowed with CNglcs following eclosion of the female. Similarly to larvae, de novo biosynthesis in female adults takes place in the integument from which CNglcs are then transported to other organs. This study demonstrates that Z. filipendulae has evolved the ability to adjust the production of CNglcs throughout its life-cycle for optimal utilization in defense and possibly other metabolic functions, while at the same time avoiding intoxication.
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      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.
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      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
       
  • Editorial Board
    • Abstract: Publication date: May 2014
      Source:Insect Biochemistry and Molecular Biology, Volume 48




      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.
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      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.
      Graphical abstract image

      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.
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      PubDate: 2014-03-31T20:20:00Z
       
  • Effects of different dietary conditions on the expression of trypsin- and
           chymotrypsin-like protease genes in the digestive system of the migratory
           locust, Locusta migratoria
    • Abstract: Publication date: Available online 17 March 2014
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Jornt Spit , Sven Zels , Senne Dillen , Michiel Holtof , Niels Wynant , Jozef Vanden Broeck
      While technological advancements have recently led to a steep increase in genomic and transcriptomic data, and large numbers of protease sequences are being discovered in diverse insect species, little information is available about the expression of digestive enzymes in Orthoptera. Here we describe the identification of Locusta migratoria serine protease transcripts (cDNAs) involved in digestion, which might serve as possible targets for pest control management. A total of 5 putative trypsin and 15 putative chymotrypsin gene sequences were characterized. Phylogenetic analysis revealed that these are distributed among 3 evolutionary conserved clusters. In addition, we have determined the relative gene expression levels of representative members in the gut under different feeding conditions. This study demonstrated that the transcript levels for all measured serine proteases were strongly reduced after starvation. On the other hand, larvae of L. migratoria displayed compensatory effects to the presence of Soybean Bowman Birk (SBBI) and Soybean Trypsin (SBTI) inhibitors in their diet by differential upregulation of multiple proteases. A rapid initial upregulation was observed for all tested serine protease transcripts, while only for members belonging to class I, the transcript levels remained elevated after prolonged exposure. In full agreement with these results, we also observed an increase in proteolytic activity in midgut secretions of locusts that were accustomed to the presence of protease inhibitors in their diet, while no change in sensitivity to these inhibitors was observed. Taken together, this paper is the first comprehensive study on dietary dependent transcript levels of proteolytic enzymes in Orthoptera. Our data suggest that compensatory response mechanisms to protease inhibitor ingestion may have appeared early in insect evolution.
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      PubDate: 2014-03-22T01:14:10Z
       
  • Identification of life-stage and tissue-specific splice variants of an
           inward rectifying potassium (Kir) channel in the yellow fever mosquito
           Aedes aegypti
    • Abstract: Publication date: Available online 18 March 2014
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Matthew F. Rouhier , Peter M. Piermarini
      Inward-rectifier potassium (Kir) channels play key roles in nerve, muscle, and epithelial cells in mammals, but their physiological roles in insects remain to be determined. The yellow fever mosquito (Aedes aegypti) possesses five different genes encoding Kir channel subunits: Kir1, Kir2A, Kir2B, Kir2B′, and Kir3. We have recently cloned and characterized the Kir1, Kir2B, and Kir3 cDNAs in the renal (Malpighian) tubules of adult female Ae. aegypti. Here we characterize the expression of the Kir2A gene in Ae. aegypti, which was not abundantly expressed in Malpighian tubules. We find that the 1) Kir2A gene is expressed primarily in the midgut and hindgut of adult female mosquitoes, and 2) Kir2A mRNAs are alternatively spliced into three distinct variants (Kir2A-a, -b, and -c). The deduced Kir2A proteins from these splice forms share a completely conserved transmembrane domain (a pore-forming domain flanked by two transmembrane-spanning segments), but possess novel NH2-terminal and/or COOH-terminal domains. Semi-quantitative RT-PCR analyses indicate that the splice variants exhibit both developmental- and tissue-specific expression. Lastly, we provide insights into the conservation of alternative splicing among the Kir2A genes of dipterans, which may add molecular diversity that compensates for the relatively limited number of Kir channel genes in insects compared to mammals.
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      PubDate: 2014-03-22T01:14:10Z
       
  • 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.
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      PubDate: 2014-03-22T01:14:10Z
       
  • Editorial Board
    • Abstract: Publication date: April 2014
      Source:Insect Biochemistry and Molecular Biology, Volume 47




      PubDate: 2014-03-17T02:21:19Z
       
  • Induction of soluble AChE expression via alternative splicing by chemical
           stress in Drosophila melanogaster
    • Abstract: Publication date: Available online 15 March 2014
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Young Ho Kim , Deok Ho Kwon , Hyo Min Ahn , Young Ho Koh , Si Hyeock Lee
      Various molecular forms of acetylcholinesterase (AChE) have been characterized in insects. Post-translational modification is known to be a major mechanism for the molecular diversity of insect AChE. However, multiple forms of Drosophila melanogaster AChE (DmAChE) were recently suggested to be generated via alternative splicing (Kim and Lee, 2013). To confirm alternative splicing as the mechanism for generating the soluble form of DmAChE, we generated a transgenic fly strain carrying the cDNA of DmAChE gene (Dm_ace) that predominantly expressed a single transcript variant encoding the membrane-anchored dimer. 3′ RACE (rapid amplification of cDNA ends) and western blotting were performed to compare Dm_ace transcript variants and DmAChE forms between wild-type and transgenic strains. Various Dm_ace transcripts and DmAChE molecular forms were observed in wild-type flies, whereas the transgenic fly predominantly expressed Dm_ace transcript variant encoding the membrane-anchored dimer. This supports alternative splicing as the major determinant in the generation of multiple forms of DmAChE. In addition, treatment with DDVP as a chemical stress induced the expression of the Dm_ace splice variant without the glycosylphosphatidylinositol anchor site in a dose-dependent manner and, accordingly, the soluble form of DmAChE in wild-type flies. In contrast, little soluble DmAChE was expressed in the transgenic fly upon exposure to DDVP. DDVP bioassays revealed that transgenic flies, which were unable to express a sufficient amount of soluble monomeric DmAChE, were more sensitive to DDVP compared to wild-type flies, suggesting that the soluble monomer may exert non-neuronal functions, such as chemical defense against xenobiotics.
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      PubDate: 2014-03-17T02:21:19Z
       
  • Sequence similarity and functional comparisons of pheromone receptor
           orthologs in two closely related Helicoverpa species
    • Abstract: Publication date: Available online 14 March 2014
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Xiao-Jing Jiang , Hao Guo , Chang Di , Shanlin Yu , Ligui Zhu , Ling-Qiao Huang , Chen-Zhu Wang
      The olfactory system of moth species in subfamily Heliothinae is an attractive model to study the evolution of the pheromone reception because they show distinct differentiation in sex pheromone components or ratios that activate pheromone receptors (PRs). However, functional assessment of PRs in closely related species remains largely untried. Here we present a special cloning strategy to isolate full-length cDNAs encoding candidate odorant receptors (ORs) from Helicoverpa armigera (Harm) and Helicoverpa assulta (Hass) on the basis of Heliothis virescens ORs, and investigate the functional properties of PRs to determine how the evolution of moth PRs contribute to intraspecific mating choice and speciation extension. We cloned 11 OR orthologs from H. armigera and 10 from H. assulta. We functionally characterized the responses of PRs of both species to seven pheromone compounds using the heterologous expression system of Xenopus ooctyes. HassOR13 was found to be highly tuned to the sex pheromone component Z11-16:Ald, and unexpectedly, both HarmOR14b and HassOR16 were specific for Z9-14:Ald. However, HarmOR6 and HassOR6 showed much higher specificity to Z9-16:OH than to Z9-16:Ald or Z9-14:Ald. HarmOR11, HarmOR14a, HassOR11 and HassOR14b failed to respond to the tested chemicals. Based on our results and previous research, we can show that some PR orthologs from H. armigera, H. assulta and H. virescens such as OR13s have similar ligand selectivity, but others have different ligand specificity. The combined PR function and sex pheromone component analysis suggests that the evolution of PRs can meet species-specific demands.
      Graphical abstract image

      PubDate: 2014-03-17T02:21:19Z
       
  • Duplication of acetylcholinesterase gene in diamondback moth strains with
           different sensitivities to acephate
    • Abstract: Publication date: Available online 13 March 2014
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Shoji Sonoda , Xueyan Shi , Dunlun Song , Pei Liang , Xiwu Gao , Youjun Zhang , Jianhong Li , Yong Liu , Ming Li , Masaya Matsumura , Sachiyo Sanada , Chieka Minakuchi , Toshiharu Tanaka , Tadashi Miyata
      This study examined the acetylcholinesterase 1 gene (AChE1) in P. xylostella strains with different sensitivities to acephate. Multiple haplotypes of the gene were found in the field-collected strains including distinct haplotypes carrying one or both previously reported mutations (A298S and G324A). Moreover, sequencing results indicated the presence of duplicated copies of the gene in the field-collected strains. No correlation was found between copy numbers of AChE1 and levels of resistance to acephate suggesting that extensive AChE1 duplication is not a major resistance factor at least in some P. xylostella strains. Proportions of the A298S and G324A mutations showed no correlation with levels of resistance to acephate. This suggests that acephate resistance of P. xylostella is complex and cannot be evaluated based on the AChE1 copy number or proportions of the resistance mutations alone.
      Graphical abstract image

      PubDate: 2014-03-17T02:21:19Z
       
  • Identification of Pheromone Components and their Binding Affinity to the
           Odorant Binding Protein CcapOBP83a-2 of the Mediterranean Fruit Fly,
           Ceratitis capitata
    • Abstract: Publication date: Available online 7 March 2014
      Source:Insect Biochemistry and Molecular Biology
      Author(s): P. Siciliano , X.L. He , C. Woodcock , J.A. Pickett , L.M. Field , M.A. Birkett , B. Kalinova , L.M. Gomulski , F. Scolari , G. Gasperi , A.R. Malacrida , J.J. Zhou
      The Mediterranean fruit fly (or medfly), Ceratitis capitata (Wiedemann; Diptera: Tephritidae), is a serious pest of agriculture worldwide, displaying a very wide larval host range with more than 250 different species of fruit and vegetables. Olfaction plays a key role in the invasive potential of this species. Unfortunately, the pheromone communication system of the medfly is complex and still not well established. In this study, we report the isolation of chemicals emitted by sexually mature individuals during the “calling” period and the electrophysiological responses that these compounds elicit on the antennae of male and female flies. Fifteen compounds with electrophysiological activity were isolated and identified in male emissions by gas chromatography coupled to electroantennography (GC-EAG). Within the group of 15 identified compounds, 11 elicited a response in antennae of both sexes, whilst 4 elicited a response only in female antennae. The binding affinity of these compounds, plus 4 additional compounds known to be behaviourally active from other studies, was measured using C. capitata OBP, CcapOBP83a-2. This OBP has a high homology to Drosophila melanogaster OBPs OS-E and OS-F, which are associated with trichoid sensilla and co-expressed with the well-studied Drosophila pheromone binding protein LUSH. The results provide evidence of involvement of CcapOBP83a-2 in the medfly’s odorant perception and its wider specificity for (E,E)-α-farnesene, one of the five major compounds in medfly male pheromone emission. This represents the first step in the clarification of the C. capitata and pheromone reception pathway, and a starting point for further studies aimed towards the creation of new powerful attractants or repellents applicable in the actual control strategies.
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      PubDate: 2014-03-11T23:14:12Z
       
  • Cross-linking in the silks of bees, ants and hornets
    • Abstract: Publication date: Available online 7 March 2014
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Peter M. Campbell , Holly E. Trueman , Qiang Zhang , Katsura Kojima , Tsunenori Kameda , Tara D. Sutherland
      Silk production is integral to the construction of nests or cocoons for many Aculeata, stinging Hymenopterans such as ants, bees and wasps. Here we report the sequences of new aculeate silk proteins and compare cross-linking among nine native silks from three bee species (Apis mellifera, Bombus terrestris and Megachile rotundata), three ant species (Myrmecia forficata, Oecophylla smaragdina and Harpegnathos saltator) and three hornets (Vespa analis, Vespa simillima and Vespa mandarinia). The well studied silks of spiders and silkworms are comprised of large proteins that are cross-linked and stabilized predominantly by intra and intermolecular beta sheet structure. In contrast, the aculeate silks are comprised of relatively small proteins that contain central coiled coil domains and comparatively reduced amounts of beta sheet structure. The hornet silks, which have the most beta sheet structure and the greatest amount of amino acid sequence outside the coiled-coil domains, dissolve in concentrated LiBr solution and appear to be stabilized predominantly by beta sheet structure like the classic silks. In contrast, the ant and bee silks, which have less beta sheet and less sequence outside the coiled-coil domains, could not be dissolved in LiBr and appear to be predominantly stabilized by covalent cross-linking. The iso-peptide cross-linker, ε-(γ-glutamyl)-lysine that is produced by transglutaminase enzymes, was demonstrated to be present in all silks by mass spectrometry, but at greater levels in silks of ants and bees. The bee silks and ant cocoons, but not the Oecophylla nest silks, appeared to be further stabilized by tanning reactions.
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      PubDate: 2014-03-11T23:14:12Z
       
  • The Maxillary Palp of Aedes aegypti, a Model of Multisensory Integration
    • Abstract: Publication date: Available online 6 March 2014
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Jonathan D. Bohbot , Jackson T. Sparks , Joseph C. Dickens
      Female yellow-fever mosquitoes, Aedes aegypti, are obligate blood-feeders and vectors of the pathogens that cause dengue fever, yellow fever and Chikungunya. This feeding behavior concludes a series of multisensory events guiding the mosquito to its host from a distance. The antennae and maxillary palps play a major role in host detection and other sensory-mediated behaviors. Compared to the antennae, the maxillary palps are a relatively simple organ and thus an attractive model for exploration of the neuromolecular networks underlying chemo- and mechanosensation. In this study, we surveyed the expressed genetic components and examined their potential involvement with these sensory modalities. Using Illumina sequencing, we identified the transcriptome of the maxillary palps of physiologically mature female Ae. aegypti. Genes expressed in the maxillary palps included those involved in sensory reception, signal transduction and neuromodulation. In addition to previously reported chemosensory genes, we identified candidate transcripts potentially involved in mechanosensation and thermosensation. This survey lays the groundwork to explore sensory networks in an insect appendage. The identification of genes involved in thermosensation provides prospective molecular targets for the development of chemicals aimed at disrupting the behavior of this medically important insect.
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      PubDate: 2014-03-06T21:23:09Z
       
  • Global distribution and origin of target site insecticide resistance
           mutations in Tetranychus urticae
    • Abstract: Publication date: Available online 3 March 2014
      Source:Insect Biochemistry and Molecular Biology
      Author(s): A. Ilias , J. Vontas , A. Tsagkarakou
      The control of Tetranychus urticae, a worldwide agricultural pest, is largely dependent on pesticides. However, their efficacy is often compromised by the development of resistance. Recent molecular studies identified a number of target site resistance mutations, such as G119S, A201S, T280A, G328A, F331W in the acetylcholinesterase gene, L1024V, A1215D, F1538I in the voltage-gated sodium channel gene, G314D and G326E in glutamate-gated chloride channel genes, G126S, I136T, S141F, D161G, P262T in the cytochrome b and the I1017F in the chitin synthase 1 gene. We examined their distribution, by sequencing the relevant gene fragments in a large number of T. urticae collections from a wide geographic range. Our study revealed that most of the resistance mutations are spread worldwide, with remarkably variable frequencies. Furthermore, we analyzed the variability of the ace locus, which has been subjected to longer periods of selection pressure historically, to investigate the evolutionary origin of ace resistant alleles and determine whether they resulted from single or multiple mutation events. By sequencing a 1540 bp ace fragment, encompassing the resistance mutations and downstream introns in 139 T. urticae individuals from 27 countries, we identified 6 susceptible and 31 resistant alleles which have arisen from at least three independent mutation events. The frequency and distribution of these ace haplotypes varied geographically, suggesting an interplay between different mutational events, gene flow and local selection.
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      PubDate: 2014-03-06T21:23:09Z
       
  • The genetics of chemoreception in the labella and tarsi of Aedes aegypti
    • Abstract: Publication date: Available online 26 February 2014
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Jackson T. Sparks , Jonathan D. Bohbot , Joseph C. Dickens
      The yellow-fever mosquito Aedes aegypti is a major vector of human diseases, such as dengue, yellow fever, chikungunya and West Nile viruses. Chemoreceptor organs on the labella and tarsi are involved in human host evaluation and thus serve as potential foci for the disruption of blood feeding behavior. In addition to host detection, these contact chemoreceptors mediate feeding, oviposition and conspecific recognition; however, the molecular landscape of chemoreception in these tissues remains mostly uncharacterized. Here we report the expression profile of all putative chemoreception genes in the labella and tarsi of both sexes of adult Ae. aegypti and discuss their possible roles in the physiology and behavior of this important disease vector.
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      PubDate: 2014-03-01T23:49:44Z
       
  • Semi-quantitative analysis of changes in the plasma peptidome of Manduca
           sexta larvae and their correlation with the transcriptome variations upon
           immune challenge
    • Abstract: Publication date: Available online 22 February 2014
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Shuguang Zhang , Xiaolong Cao , Yan He , Steve Hartson , Haobo Jiang
      The tobacco hornworm, Manduca sexta, has been used as a biochemical model for studying insect physiological processes. While the transcriptomes of its fat body, hemocytes, midgut, and antennae have been examined in several studies, limited information is available for proteins in tissues, cells, or body fluids of this insect. In keeping pace with the M. sexta genome project, we launched a pilot study to identify differences in the peptidome of cell-free hemolymph samples from larvae injected with buffer or a mixture of bacteria. At 24 h after injection, plasma was collected and treated with 50% acetonitrile to precipitate large proteins. The supernatants, containing peptides (<25 kDa) and other stable proteins (>25 kDa), were digested with trypsin and analyzed by nano-liquid chromatography and nano-electrospray tandem mass spectrometry (nanoLC-MS/MS) on an LTQ Orbitrap XL mass spectrometer. Known M. sexta cDNA sequences and gene transcripts from the draft genome were translated in silico to generate a database of polypeptides (i.e. peptides and proteins) in this species. By searching the database, we identified 268 hemolymph polypeptides, 50 of which showed 1.67 to 200 fold abundance increases after the immune challenge, as judged by significant changes in normalized spectral counts between the control and induced plasma. These included a total of 33 antimicrobial peptides (attacins, cecropins, defensins, diapausins, gallerimycin, gloverin, lebocins, lysozymes), pattern recognition receptors, and proteinase inhibitors. Although there was no strong parallel (correlation coefficients: -0.13, 0.11, 0.39 and 0.62) between plasma peptide levels and their transcript levels in control or induced hemocytes or fat body, we observed the mRNA level changes in hemocytes and fat body concurred with their peptide level changes with correlation coefficients of 0.67 and 0.76, respectively. These data suggest that fat body contributed a significant portion of the plasma polypeptides involved in various aspects of innate immunity after the bacterial injection.
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      PubDate: 2014-02-25T02:54:19Z
       
  • The progress and future of enhancing antiviral capacity by transgenic
           technology in the silkworm Bombyx mori
    • Abstract: Publication date: Available online 20 February 2014
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Liang Jiang , Qingyou Xia
      Bombyx mori is a common lepidopteran model and an important economic insect for silk production. B. mori nucleopolyhedrovirus (BmNPV) is a typical pathogenic baculovirus that causes serious economic losses in sericulture. B. mori and BmNPV are a model of insect host and pathogen interaction including invasion of the host by the pathogen, host response, and enhancement of host resistance. The antiviral capacity of silkworms can be improved by transgenic technology such as overexpression of an endogenous or exogenous antiviral gene, RNA interference of the BmNPV gene, or regulation of the immune pathway to inhibit BmNPV at different stages of infection. Antiviral capacity could be further increased by combining different methods. We discuss the future of an antiviral strategy in silkworm, including possible improvement of anti-BmNPV, the feasibility of constructing transgenic silkworms with resistance to multiple viruses, and the safety of transgenic silkworms. The silkworm model could provide a reference for disease control in other organisms.


      PubDate: 2014-02-20T07:15:48Z
       
  • Yolk proteins in the male reproductive system of the fruit fly Drosophila
           melanogaster: spatial and temporal patterns of expression
    • Abstract: Publication date: Available online 17 February 2014
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Magdalena M. Majewska , Agnieszka Suszczynska , Joanna Kotwica-Rolinska , Tomasz Czerwik , Bohdan Paterczyk , Marta A. Polanska , Piotr Bernatowicz , Piotr Bebas
      In insects, spermatozoa develop in the testes as clones of single spermatogonia covered by specialized somatic cyst cells (cc). Upon completion of spermatogenesis, spermatozoa are released to the vas deferens, while the cc remain in the testes and die. In the fruit fly Drosophila melanogaster, the released spermatozoa first reach the seminal vesicles (SV), the organ where post-testicular maturation begins. Here, we demonstrate the temporal (restricted to the evening and early night hours) accumulation of membranous vesicles containing proteins in the SV lumen of D. melanogaster. When SV vesicles were isolated from the semen and co-incubated with testis-derived spermatozoa in vitro, their contents bound to the spermatozoa along their tails. The proteins of the SV vesicles were then characterized using 2-D electrophoresis. We identified a prominent protein spot of around 45-47 kDa, which disappears from the SV vesicles in the night, i.e. shortly after they appear in the SV lumen. Sequencing of peptides derived from this spot by mass spectrometry revealed identity with three yolk proteins (YP1-3). This unexpected result was confirmed by western blotting, which demonstrated that SV vesicles contain proteins that are immunoreactive with an antibody against D. melanogaster YP1-3. The expression of all yp genes was shown to be a unique feature of testis tissues. Using RNA probes we found that their transcripts localize exclusively to the cc that cover fully developed spermatozoa in the distal part of each testis. Temporally, the expression of yp genes was found to be restricted to a short period during the day and is followed by the evening accumulation of YP proteins in the cc. Immunohistochemical staining confirmed that cc are the source of SV vesicles containing YPs that are released into the SV lumen. These vesicles interact with spermatozoa and as a result, YPs become extrinsic proteins of the sperm membrane. Thus, we describe for the first time the expression of yolk proteins in the male reproductive system of D. melanogaster under physiological conditions, and show that somatic cells of the testes are the source of these proteins.
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      PubDate: 2014-02-20T07:15:48Z
       
  • Editorial Board
    • Abstract: Publication date: March 2014
      Source:Insect Biochemistry and Molecular Biology, Volume 46




      PubDate: 2014-02-15T04:15:42Z
       
  • Identification of conserved and novel microRNAs in Manduca sexta and their
           possible roles in the expression regulation of immunity-related genes
    • Abstract: Publication date: Available online 5 February 2014
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Xiufeng Zhang , Yun Zheng , Guru Jagadeeswaran , Ren Ren , Ramanjulu Sunkar , Haobo Jiang
      The tobacco hornworm Manduca sexta has served as a model for insect biochemical and physiological research for decades. However, knowledge of the posttranscriptional regulation of gene expression by microRNAs is still rudimentary in this species. Our previous study (Zhang et al., 2012) identified 163 conserved and 13 novel microRNAs in M. sexta, most of which were present at low levels in pupae. To identify additional M. sexta microRNAs and more importantly to examine their possible roles in the expression regulation of immunity-related genes, we constructed four small RNA libraries using fat body and hemocytes from naïve or bacteria-injected larvae and obtained 32.9 million reads of 18-31 nucleotides by Illumina sequencing. Mse-miR-929 and mse-miR-1b (antisense microRNA of mse-miR-1) were predicted in the previous study and now found to be conserved microRNAs in the tissue samples. We also found four novel microRNAs, two of which result from a gene cluster. Mse-miR-281-star, mse-miR-965-star, mse-miR-31-star, and mse-miR-9b-star were present at higher levels than their respective mature strands. Abundance changes of microRNAs were observed after the immune challenge. Based on the quantitative data of mRNA levels in control and induced fat body and hemocytes as well as the results of microRNA target site prediction, we suggest that certain microRNAs and microRNA*s regulate gene expression for pattern recognition, prophenoloxidase activation, cellular responses, antimicrobial peptide synthesis, and conserved intracellular signal transduction (Toll, IMD, JAK-STAT, MAPK-JNK-p38, and small interfering RNA pathways). In summary, this study has enriched our knowledge on M. sexta microRNAs and how some of them may participate in the expression regulation of immunity-related genes.
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      PubDate: 2014-02-05T07:20:02Z
       
  • Genomic analysis of the interactions between social environment and social
           communication systems in honey bees (Apis mellifera)
    • Abstract: Publication date: Available online 31 January 2014
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Osnat Malka , Elina L. Niño , Christina M. Grozinger , Abraham Hefetz
      Social context is often a primary regulator of social behavior, but genes that affect or are affected by social context have rarely been investigated. In social insects, caste specific pheromones are key modulators of social behavior, e.g., in honey bees the queen mandibular gland (MG) pheromone mediates reproductive dominance, its absence prompting ovary activation and queen pheromone production in workers. Here, we investigate the effect of social environment on genome-wide expression patterns in the MG, to determine how social context modulates expression of genes that, in turn alter social environment. We used microarrays to examine the MGs of virgin and mated queens, and queenright (QR) and queenless (QL) workers with or without activated ovaries. Approximately 2554 transcripts were significantly differentially expressed among these groups, with caste and social context being the main regulators of gene expression patterns, while physiological state (ovary activation) only minimally affecting gene expression. Thus, social context strongly regulates expression of genes, which, in turn, shape social environment. Among these, 25 genes that are putatively involved in caste selective production of the fatty-acid derived MG pheromone were differentially expressed in queens and workers. These genes whose functions correspond with enzymatic or transport processes emphasize the occurrence of disparate pheromone biosynthetic pathways for queens and workers, adding another dimension regarding the regulation of these important pheromones. Gene ontology analysis also revealed genes of different functional categories whose expression was impacted by caste or by the social environment, suggesting that the MG has broader functions than pheromone biosynthesis.
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      PubDate: 2014-02-05T07:20:02Z
       
  • A recombinant fusion protein containing a spider toxin specific for the
           insect voltage-gated sodium ion channel shows oral toxicity towards
           insects of different orders
    • Abstract: Publication date: Available online 29 January 2014
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Sheng Yang , Prashant Pyati , Elaine Fitches , John A. Gatehouse
      Recombinant fusion protein technology allows specific insecticidal protein and peptide toxins to display activity in orally-delivered biopesticides. The spider venom peptide δ-amaurobitoxin-PI1a, which targets insect voltage-gated sodium channels, was fused to the "carrier" snowdrop lectin (GNA) to confer oral toxicity. The toxin itself (PI1a) and an amaurobitoxin / GNA fusion protein (PI1a/GNA) were produced using the yeast Pichia pastoris as expression host. Although both proteins caused mortality when injected into cabbage moth (Mamestra brassicae) larvae, the PI1a/GNA fusion was approximately 6 times as effective as recombinant PI1a on a molar basis. PI1a alone was not orally active against cabbage moth larvae, but a single 30μg dose of the PI1a/GNA fusion protein caused 100% larval mortality within 6 days when fed to 3rd instar larvae, and caused significant reductions in survival, growth and feeding in 4th - 6th instar larvae. Transport of fusion protein from gut contents to the haemolymph of cabbage moth larvae, and binding to the nerve chord, was shown by Western blotting. The PI1a/GNA fusion protein also caused mortality when delivered orally to dipteran (Musca domestica; housefly) and hemipteran (Acyrthosiphon pisum; pea aphid) insects, making it a promising candidate for development as a biopesticide.
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      PubDate: 2014-01-31T22:19:54Z
       
  • Identification of two acetylcholinesterases in Pardosa pseudoannulata and
           the sensitivity to insecticides
    • Abstract: Publication date: Available online 23 January 2014
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Yixi Zhang , Ying Shao , Feng Jiang , Jian Li , Zewen Liu
      Pardosa pseudoannulata is an important predatory enemy against insect pests, such as rice planthoppers and leafhoppers. In order to understand the insecticide selectivity between P. pseudoannulata and insect pests, two acetylcholinesterase genes, Pp-ace1 and Pp-ace2, were cloned from this natural enemy. The putative proteins encoded by Pp-ace1 and Pp-ace2 showed high similarities to insect AChE1 (63% to Liposcelis entomophila AChE1) and AChE2 (36% to Culex quinquefasciatus AChE2) with specific functional motifs, which indicated that two genes might encode AChE1 and AChE2 proteins respectively. The recombinant proteins by expressing Pp-ace1 and Pp-ace2 genes in insect sf9 cells showed high AChE activities. The kinetic parameters, V max and K m , of two recombinant AChE proteins were significantly different. The sensitivities to six insecticides were determined in two recombinant AChEs. Pp-AChE1 was more sensitive to all tested insecticides than Pp-AChE2, such as fenobucarb (54 times in K i ratios), isoprocarb (31 times), carbaryl (13 times) and omethoate (6 times). These results indicated that Pp-AChE1 might be the major synaptic enzyme in the spider. By sequence comparison of P. pseudoannulata and insect AChEs, the key amino acid differences at or close to the functional sites were found. The locations of some key amino acid differences were consistent with the point mutation sites in insect AChEs that were associated with insecticide resistance, such as Phe331 in Pp-AChE2 corresponding to Ser331Phe mutation in Myzus persicae and Aphis gossypii AChE2, which might play important roles in insecticide selectivity between P. pseudoannulata and insect pests. Of course, the direct evidences are needed through further studies.
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      PubDate: 2014-01-27T12:18:59Z
       
  • Retrotransposon “Qian” mediated segmental duplication in
           silkworm, Bombyx mori
    • Abstract: Publication date: Available online 21 January 2014
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Yunmin Xu , Ning Jiang , Ziliang Zou , Zhijian Tu , Anli Chen , Qiaoling Zhao , Zhonghuai Xiang , Ningjia He
      Transposable elements constitute a large fraction of the eukaryotic genomes. They have the potential to alter genome structure and play a major role in genome evolution. Here, we report a segmental duplication mediated by a novel long terminal repeat (LTR) retrotransposon as the cause of an egg-shell recessive lethal mutant (l-e m mutant) in silkworm (Bombyx mori). The segmental duplication resulted in the duplication of six genes and the disruption of two genes. Disruption of BmEP80 (B. mori egg protein 80), a gene encoding a major egg-shell structure protein, is likely responsible for the lethal water-loss phenotype in the l-e m /l-e m mutant. Our data revealed that BmEP80 is present in the inner egg-shell layer and plays important roles in resistance to water efflux form eggs. A novel LTR retrotransposon (named as “Qian”) was identified and the model for the Qian-mediated chromosomal segmental duplication was proposed. Detail biochemical and genomic analyses on the l-e m mutant offer an opportunity to demonstrate that an LTR retrotransposon could trigger duplication of a chromosomal segment (∼96.3 kb) and confer novel phenotype.
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      PubDate: 2014-01-23T04:30:19Z
       
  • Evolutionary implications of dipluran hexamerins
    • Abstract: Publication date: Available online 22 January 2014
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Wei Xie , Yun-Xia Luan
      Hexamerin, as a member of the highly conserved arthropod hemocyanin superfamily, has been shown to be a good marker for the phylogenetic study of insects. However, few studies have been conducted on hexamerins in basal hexapods. The first Diplura hexamerin CspHex1 was reported only recently (Pick and Burmester, 2009). Remarkably, CspHex1 was suggested to have evolved from hexapod hemocyanin subunit type 2, which is very different from all insect hexamerins originated from hexapod hemocyanin subunit type 1. Does this finding suggest double or even multiple origins of hexamerins in Hexapoda? To find more evidence on the evolution of dipluran hexamerins, eight putative hexamerin gene sequences were obtained from three dipluran species, as were three hemocyanin genes from two collembolan species. Unexpectedly, after adding the new sequences into the phylogenetic analyses, all dipluran hexamerins including CspHex1 grouped together and as sister to the insect hexamerins, with high likelihood and Bayesian support. Our analysis supports a single origin of the hexamerins in Hexapoda, and suggests the close relationship between Diplura and Insecta. In addition, our study indicates that a relatively comprehensive taxa sampling is essential to solve some problems in phylogenetic reconstruction.
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      PubDate: 2014-01-23T04:30:19Z
       
  • Identification, functional characterization and phylogenetic analysis of
           double stranded RNA degrading enzymes present in the gut of the desert
           locust, Schistocerca gregaria
    • Abstract: Publication date: Available online 10 January 2014
      Source:Insect Biochemistry and Molecular Biology
      Author(s): Niels Wynant , Dulce Santos , Rik Verdonck , Jornt Spit , Pieter Van Wielendaele , Jozef Vanden Broeck
      RNA interference (RNAi) has become a widely used reverse genetics tool in eukaryotes and holds great potential to contribute to the development of novel strategies for insect pest control. While previous studies clearly demonstrated that injection of dsRNA into the body cavity of the desert locust, Schistocerca gregaria, is highly effective to induce gene silencing effects, we observed that the RNAi response is much less sensitive to orally delivered dsRNA. In line with this, we report on the presence of a potent dsRNA degrading activity in the midgut juice. Four different dsRNase sequences that belong to the DNA/RNA Non-specific Nuclease superfamily were retrieved from a transcriptome database of the desert locust. Surprisingly, we have found that, in the publicly available eukaryote nucleotide sequence databases, the presence of this group of enzymes is restricted to insects and crustaceans. Nonetheless, phylogenetic analyses predict a common origin of these enzymes with the Endonuclease G (EndoG) Non-specific Nucleases that display a widespread taxonomic distribution. Moreover, in contrast to the Sg-endoG transcript, the four Sg-dsRNase transcripts appear to be specifically expressed in the gut. Finally, by means of RNAi, we provide evidence for an important contribution of dsRNase2 to the dsRNA degrading activity that is present in the gut lumen of S. gregaria.
      Graphical abstract image

      PubDate: 2014-01-11T07:16:02Z
       
 
 
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