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BIOCHEMISTRY (220 journals)                  1 2 3     

AAPS PharmSciTech     Hybrid Journal   (Followers: 7)
Acetic Acid Bacteria     Open Access   (Followers: 1)
ACS Central Science     Hybrid Journal   (Followers: 1)
ACS Chemical Biology     Full-text available via subscription   (Followers: 172)
ACS Chemical Neuroscience     Full-text available via subscription   (Followers: 17)
Acta Crystallographica Section D : Biological Crystallography     Hybrid Journal   (Followers: 12)
Acta Crystallographica Section F: Structural Biology Communications     Hybrid Journal   (Followers: 7)
Advances and Applications in Bioinformatics and Chemistry     Open Access   (Followers: 9)
Advances in Biological Chemistry     Open Access   (Followers: 6)
Advances in Carbohydrate Chemistry and Biochemistry     Full-text available via subscription   (Followers: 11)
Advances in Plant Biochemistry and Molecular Biology     Full-text available via subscription   (Followers: 7)
Advances in Protein Chemistry and Structural Biology     Full-text available via subscription   (Followers: 12)
African Journal of Biochemistry Research     Open Access   (Followers: 1)
African Journal of Chemical Education     Open Access   (Followers: 2)
Alkaloids: Chemical and Biological Perspectives     Full-text available via subscription   (Followers: 4)
American Journal of Biochemistry     Open Access   (Followers: 7)
American Journal of Biochemistry and Biotechnology     Open Access   (Followers: 88)
American Journal of Biochemistry and Molecular Biology     Open Access   (Followers: 12)
American Journal of Polymer Science     Open Access   (Followers: 24)
Amino Acids     Hybrid Journal   (Followers: 8)
Analytical Biochemistry     Hybrid Journal   (Followers: 157)
Annals of Clinical Biochemistry     Hybrid Journal   (Followers: 8)
Annual Review of Biochemistry     Full-text available via subscription   (Followers: 49)
Annual Review of Chemical and Biomolecular Engineering     Full-text available via subscription   (Followers: 11)
Applied Biochemistry and Biotechnology     Hybrid Journal   (Followers: 43)
Applied Biochemistry and Microbiology     Hybrid Journal   (Followers: 15)
Applied Organometallic Chemistry     Hybrid Journal   (Followers: 5)
Archives of Biochemistry and Biophysics     Hybrid Journal   (Followers: 21)
Archives of Insect Biochemistry and Physiology     Hybrid Journal   (Followers: 1)
Archives Of Physiology And Biochemistry     Hybrid Journal   (Followers: 1)
Asian Journal of Biochemistry     Open Access   (Followers: 1)
Asian Journal of Biomedical and Pharmaceutical Sciences     Open Access   (Followers: 3)
Avicenna Journal of Medical Biochemistry     Open Access  
Bangladesh Journal of Medical Biochemistry     Open Access   (Followers: 2)
BBA Clinical     Open Access  
BBR : Biochemistry and Biotechnology Reports     Open Access   (Followers: 4)
Biocatalysis     Open Access  
Biochemical and Biophysical Research Communications     Hybrid Journal   (Followers: 20)
Biochemical and Molecular Medicine     Full-text available via subscription   (Followers: 5)
Biochemical Compounds     Open Access  
Biochemical Engineering Journal     Hybrid Journal   (Followers: 14)
Biochemical Genetics     Hybrid Journal   (Followers: 3)
Biochemical Journal     Full-text available via subscription   (Followers: 26)
Biochemical Pharmacology     Hybrid Journal   (Followers: 8)
Biochemical Society Transactions     Full-text available via subscription   (Followers: 3)
Biochemical Systematics and Ecology     Hybrid Journal   (Followers: 4)
Biochemistry     Full-text available via subscription   (Followers: 220)
Biochemistry & Pharmacology : Open Access     Open Access   (Followers: 1)
Biochemistry & Physiology : Open Access     Open Access  
Biochemistry (Moscow)     Hybrid Journal   (Followers: 3)
Biochemistry (Moscow) Supplement Series A: Membrane and Cell Biology     Hybrid Journal   (Followers: 3)
Biochemistry (Moscow) Supplemental Series B: Biomedical Chemistry     Hybrid Journal   (Followers: 3)
Biochemistry and Cell Biology     Full-text available via subscription   (Followers: 16)
Biochemistry and Molecular Biology Education     Hybrid Journal   (Followers: 5)
Biochemistry and Molecular Biology of Fishes     Full-text available via subscription   (Followers: 1)
Biochemistry Research International     Open Access   (Followers: 5)
Biochimica et Biophysica Acta (BBA) - Molecular and Cell Biology of Lipids     Hybrid Journal   (Followers: 7)
Biochimica et Biophysica Acta (BBA) - Molecular Basis of Disease     Hybrid Journal   (Followers: 16)
Biochimica et Biophysica Acta (BBA) - Molecular Cell Research     Hybrid Journal   (Followers: 6)
Biochimie     Hybrid Journal   (Followers: 5)
Bioconjugate Chemistry     Full-text available via subscription   (Followers: 28)
BioDrugs     Full-text available via subscription   (Followers: 8)
Bioelectrochemistry     Hybrid Journal   (Followers: 2)
Biofuels     Hybrid Journal   (Followers: 13)
Biogeochemistry     Hybrid Journal   (Followers: 10)
BioInorganic Reaction Mechanisms     Hybrid Journal   (Followers: 1)
Biokemistri     Open Access  
Biological Chemistry     Partially Free   (Followers: 27)
Biomaterials Research     Open Access   (Followers: 2)
Biomedicines     Open Access   (Followers: 1)
BioMolecular Concepts     Hybrid Journal   (Followers: 2)
Bioscience, Biotechnology, and Biochemistry     Hybrid Journal   (Followers: 26)
Biosimilars     Open Access   (Followers: 1)
Biotechnology and Applied Biochemistry     Hybrid Journal   (Followers: 45)
Bit├ícora Digital     Open Access  
BMC Biochemistry     Open Access   (Followers: 12)
Bulletin of University of Agricultural Sciences and Veterinary Medicine Cluj-Napoca : Food Science and Technology     Open Access  
Carbohydrate Polymers     Hybrid Journal   (Followers: 10)
Cell Biochemistry and Biophysics     Hybrid Journal   (Followers: 6)
Cell Biochemistry and Function     Hybrid Journal   (Followers: 4)
Cellular Physiology and Biochemistry     Open Access   (Followers: 3)
Central European Journal of Chemistry     Hybrid Journal   (Followers: 6)
ChemBioChem     Hybrid Journal   (Followers: 6)
Chemical and Biological Technologies for Agriculture     Open Access   (Followers: 1)
Chemical Biology & Drug Design     Hybrid Journal   (Followers: 24)
Chemical Engineering Journal     Hybrid Journal   (Followers: 25)
Chemical Senses     Hybrid Journal   (Followers: 1)
Chemical Speciation and Bioavailability     Open Access   (Followers: 1)
Chemico-Biological Interactions     Hybrid Journal   (Followers: 3)
Chemistry & Biodiversity     Hybrid Journal   (Followers: 5)
Chemistry & Biology     Full-text available via subscription   (Followers: 30)
Chemistry and Ecology     Hybrid Journal   (Followers: 1)
ChemTexts     Hybrid Journal  
Clinical Biochemist Reviews     Full-text available via subscription   (Followers: 1)
Clinical Biochemistry     Hybrid Journal   (Followers: 19)
Clinical Chemistry and Laboratory Medicine     Hybrid Journal   (Followers: 60)
Clinical Lipidology     Full-text available via subscription  
Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology     Hybrid Journal   (Followers: 4)
Comparative Biochemistry and Physiology Part B: Biochemistry and Molecular Biology     Hybrid Journal   (Followers: 1)
Comparative Biochemistry and Physiology Part C: Toxicology & Pharmacology     Hybrid Journal   (Followers: 7)

        1 2 3     

Journal Cover Archives of Insect Biochemistry and Physiology
  [SJR: 0.663]   [H-I: 48]   [1 followers]  Follow
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 0739-4462 - ISSN (Online) 1520-6327
   Published by John Wiley and Sons Homepage  [1598 journals]
  • Hormonal and nutritional regulation of insect fat body development and
    • Abstract: The insect fat body is an organ analogue to vertebrate adipose tissue and liver and functions as a major organ for nutrient storage and energy metabolism. Similar to other larval organs, fat body undergoes a developmental “remodeling” process during the period of insect metamorphosis, with the massive destruction of obsolete larval tissues by programmed cell death and the simultaneous growth and differentiation of adult tissues from small clusters of progenitor cells. Genetic ablation of Drosophila fat body cells during larval‐pupal transition results in lethality at the late pupal stage and changes sizes of other larval organs indicating that fat body is the center for pupal development and adult formation. Fat body development and function are largely regulated by several hormonal (i.e. insulin and ecdysteroids) and nutritional signals, including oncogenes and tumor suppressors in these pathways. Combining silkworm physiology with fruitfly genetics might provide a valuable system to understand the mystery of hormonal regulation of insect fat body development and function. © 2009 Wiley Periodicals, Inc.
      PubDate: 2009-02-03T00:00:00-05:00
      DOI: 10.1002/arch.20291
    • Abstract: The ATP‐binding cassette (ABC) transporters are important transmembrane proteins encoded by a supergene family. The majority of ABC proteins are primary active transporters that bind and hydrolyze ATP to mediate the efflux of a diverse range of substrates across lipid membranes. In this study, we cloned and characterized a putative multidrug resistance associated protein 1 (MRP1) from Rhopalosiphum padi encoded by ABCC1. Structural analysis showed that this protein has structural features typical of the ABC transporter family. Phylogenetic analysis indicated that the amino acid sequence was highly similar that of the corresponding protein from Acyrthosiphon pisum. Real‐time quantitative polymerase chain reaction (PCR) analysis showed that ABCC1 was expressed throughout all R. padi developmental stages, with the highest level of expression in the fourth larval instar. We also examined ABCC1 expression in four different tissue types and found that it was most highly expressed in the midgut. Exposing R. padi to imidacloprid and chlorpyrifos increased ABCC1 expression. Furthermore, ABCC1 expression was higher in the imidacloprid‐resistant (IR) and chlorpyrifos‐resistant (CR) strains than in an insecticide‐susceptible strain (SS) of R. padi. Exposing R. padi to verapamil in combination with insecticides significantly increased the toxicity of the insecticides. The respective synergy factor of CR and IR R. padi strain was 1.33 and 1.26, which was lower than that (2.72 and 1.64, respectively) of the SS. Our results clarify the biological function of ABCC1 in R. padi, particularly its role in insecticide resistance, and suggest novel strategies for pest management that use ABC transporter inhibitors to increase the effectiveness of insecticides.
  • Issue Information
    • Abstract: In this study, the cDNAs of five cytochromes P450 genes (named CYP345P1, CYP358B1, CYP4FD2, CYP4CD2, and CYP6JN1) contained open reading frames from 1,500 to 1,554 nucleotides that encoded 499 to 517 amino acids were cloned from the psocid Liposcelis entomophila. They are characterized by predicted molecular weights from 57.67 to 59.64 kDa and theoretical isoelectric points of 5.57–9.07. Quantitative real‐time PCR analysis showed these five genes were expressed at all tested developmental stages and higher expressions were observed in adults. CYP358B1 was expressed at higher levels in egg and adult compared to the larval stages. mRNA abundances of five genes were detected in both sexes and were relatively more abundant in adult females than in adult males. Synergism bioassay showed that the synergic ratio was 2.20 and 2.45 when insects were treated with the mixture of deltamethrin or malathion with the synergist piperonyl butoxide (PBO). Because PBO induces cytochrome P450s in some insects, this suggested to us that cytochromes P450 might participate in detoxification of these insecticides. The transcripts of the five cytochromes P450 genes in adult psocids could be induced to the highest level at 12 h after the exposure to malathion. After exposure to deltamethrin, CYP358B1 reached maximum expression at 24 h. The maximum expression of the other four genes occurred at 36 h. Treatments with the carbamate propoxur did not influence transcription of the cytochromes P450 gene. The induction profiles suggested that these five cytochrome P450 genes may be associated with deltamethrin and malathion metabolism in psocids.
           flavipes (Blattodea: Rhinotermitidae): IDENTIFICATION AND CHARACTERIZATION
    • Abstract: The peritrophic matrix (PM) is an acellular structure that lines the gut of most insects. It is an attractive target for pest management strategies because of its close involvement in digestive processes and role as a barrier against pathogens and toxins. The purpose of this study was to identify and characterize the genes that translate for principal components of the Reticulitermes flavipes PM. Genes encoding a gut chitin synthase (CHS), two proteins with peritrophin‐A domains, and a chitin deacetylase were identified from an R. flavipes symbiont‐free gut cDNA library, a pyrosequencing study of termite lignocellulose digestion, and a metatranscriptomic analysis of R. flavipes fed on agricultural biomass. Quantitative expression analysis of the identified genes, in the termite digestive tract, revealed that the transcripts coding for a CHS (RfCHSB) and the proteins with peritrophin‐A domains (RfPPAD1 and RfPPAD2) were predominantly expressed in the midgut, suggesting an association with the PM. The peritrophin identity of the RfPPAD2 gene was confirmed by immunodetection of its translated peptide in the midgut and PM. The discovery and characterization of PM components of R. flavipes provides a basis for further investigation of the viability of this structure as a target for candidate termiticides.
    • Abstract: The sterile insect technique (SIT) was developed to eradicate the new world screwworm from the southern United States and Mexico, and became a component of many area‐wide integrated pest management programs, particularly useful in managing tephritid fruit flies. SIT is based on the idea of rearing and sterilizing male pests, originally by ionizing radiation, and then releasing into field, where they compete for and mate with wild females. Mating with sterile males leads to reduced fecundity to lower pest populations. There are concerns with the use and distribution of radioisotopes for SIT programs, which have led to developing X‐ray irradiation protocols to sterilize insects. We considered the possibility that X‐ray irradiation exerts sublethal impacts aside form sterilizing insects. Such effects may not be directly observable, which led us to the hypothesis that X‐ray irradiation in one life stage creates alterations in biological fitness and protein expression in the subsequent stage. We tested our hypothesis by irradiating larvae of Bactrocera dorsalis. There are two major points. One, exposing larvae to X‐ray treatments led to reduced adult emergence, fecundity, fertility, and flight capacity from the corresponding pupae and emerged adults. Two, the X‐ray treatments led to substantial expression changes in 27 pupal proteins. We assorted the 67 spots representing these proteins into three groups, metabolism, development, and structure. Our interpretation is these X‐ray induced changes in biological performance and protein expression indicate their adult counterparts may be disabled in their abilities to successfully compete for and mate wild females in native habitats.
           melanogaster GLUTATHIONE S‐TRANSFERASE D3 (DmGSTD3)
    • Abstract: Drosophila melanogaster glutathione S‐transferase D3 (DmGSTD3) has a shorter amino acid sequence as compared to other GSTs known in the fruit flies. This is due to the 15 amino acid N‐terminal truncation in which normally active amino acid residue is located. The work has made use of homology modeling to visualize the arrangement of amino acid side chains in the glutathione (GSH) substrate cavity. The identified amino acids were then replaced with amino acids without functional groups in the side chains and the mutants were analyzed kinetically. Homology modeling revealed that the side chains of Y89 and Y97 were shown facing toward the substrate cavity proposing their possible role in catalyzing the conjugation. Y97A and Y89A GSH gave large changes in Km (twofold increase), Vmax (fivefold reduction), and Kcat/Km values for GSH suggesting their significant role in the conjugation reaction. The replacement at either positions has not affected the affinity of the enzyme toward 1‐chloro‐2,4‐dinitrobenzene as no significant change in values of Kmax was observed. The replacement, however, had significantly reduced the catalytic efficiency of both mutants with (Kcat/Km)GSH and (Kcat/Km)CDNB of eight‐ and twofold reduction. The recombinant DmGSTD3 has shown no activity toward 1,2‐dichloro‐4‐nitrobenzene, 2,4‐hexadienal, 2,4‐heptadienal, p‐nitrobenzyl chloride, ethacrynic acid, and sulfobromophthalein. Therefore, it was evident that DmGSTD3 has made use of distal amino acids Y97 and Y89 for GSH conjugation.
           NORTH AMERICA
    • Abstract: Emerging and re‐emerging tick‐borne diseases threaten public health and the wellbeing of domestic animals and wildlife globally. The adoption of an evolutionary ecology framework aimed to diminish the impact of tick‐borne diseases needs to be part of strategies to protect human and animal populations. We present a review of current knowledge on the adaptation of ticks to their environment, and the impact that global change could have on their geographic distribution in North America. Environmental pressures will affect tick population genetics by selecting genotypes able to withstand new and changing environments and by altering the connectivity and isolation of several tick populations. Research in these areas is particularly lacking in the southern United States and most of Mexico with knowledge gaps on the ecology of these diseases, including a void in the identity of reservoir hosts for several tick‐borne pathogens. Additionally, the way in which anthropogenic changes to landscapes may influence tick‐borne disease ecology remains to be fully understood. Enhanced knowledge in these areas is needed in order to implement effective and sustainable integrated tick management strategies. We propose to refocus ecology studies with emphasis on metacommunity‐based approaches to enable a holistic perspective addressing whole pathogen and host assemblages. Network analyses could be used to develop mechanistic models involving multihost–pathogen communities. An increase in our understanding of the ecology of tick‐borne diseases across their geographic distribution will aid in the design of effective area‐wide tick control strategies aimed to diminish the burden of pathogens transmitted by ticks.
    • Abstract: Fatty acid desaturases are metabolic setscrews. To study their systemic impact on growth in Drosophila melanogaster, we inhibited fatty acid desaturases using the inhibitor CAY10566. As expected, the amount of desaturated lipids is reduced in larvae fed with CAY10566. These animals cease feeding soon after hatching, and their growth is strongly attenuated. A starvation program is not launched, but the expression of distinct metabolic genes is activated, possibly to mobilize storage material. Without attaining the normal size, inhibitor‐fed larvae molt to the next stage indicating that the steroid hormone ecdysone triggers molting correctly. Nevertheless, after molting, expression of ecdysone‐dependent regulators is not induced. While control larvae molt a second time, these larvae fail to do so and die after few days of straying. These effects are similar to those observed in experiments using larvae deficient for the fatty acid desaturase1 gene. Based on these data, we propose that the ratio of saturated to unsaturated fatty acids adjusts a sensor system that directs feeding behavior. We also hypothesize that loss of fatty acid desaturase activity leads to a block of the genetic program of development progression indirectly by switching on a metabolic compensation program.
    • Abstract: The hemichannel and gap junction channel are major portals for the release of factors responsible for the effects of apoptotic cells on the spread of apoptosis to neighboring cells and apoptotic corpse clearance, typically by phagocytes. The N‐terminal cytoplasmic domain in the connexins, gap junction proteins in vertebrate, has been implicated in regulating channel closure. However, little is known about how the hemichannel close responds to apoptotic signaling transduction leading to the reduction of neighboring cellular apoptosis in an invertebrate. An insect Bac‐to‐Bac expression system, pFastBacTM HT A, allows us to construct an N‐terminally elongated SpliInx2 (Nte‐Inx2) and SpliInx3 (Nte‐Inx3). Here, we demonstrated that recombinant baculovirus Bac‐Nte‐Inx2 (reBac‐Net‐Inx2) and Bac‐Nte‐Inx3 (reBac‐Nte‐Inx3) closed the endogenous hemichannel on the Sf9 cell surface. Importantly, primary baculovirus infections significantly caused early apoptosis, and this apoptosis was reduced by hemichannel‐closed Sf9 cells at 24‐h post‐infection (PI). Although N‐terminal‐elongated residue led to the increase in the phosphorylated sites in both Nte‐Inx2 and Nte‐Inx3 and an additional transmembrane domain in Nte‐Inx3, both the proteins localized on the cell surface, suggesting Nte‐Inxs proteins could mediate hemichannel closure. Further supporting evidence showed that hemichannel closure was dependent on N‐Inxs expressed by baculovirus polyhedrin promoter, which began to express at 18–24 h PI. These results identify an unconventional function of N‐terminal‐elongated innexins that could act as a plug to manipulate hemichannel closure and provide a mechanism connecting the effect of hemichannel closure directly to apoptotic signaling transduction from intracellular to extracellular compartment.
           SPLICE VARIANTS IN Leptinotarsa decemlineata (SAY)
    • Abstract: Chitin synthase (ChS) plays a critical role in chitin synthesis and excretion. In this study, two ChS genes (LdChSA and LdChSB) were identified in Leptinotarsa decemlineata. LdChSA contains two splicing variants, LdChSAa and LdChSAb. Within the first, second, and third larval instars, the mRNA levels of LdChSAa, LdChSAb, and LdChSB coincide with the peaks of circulating 20‐hydroxyecdysone (20E) and juvenile hormone (JH). In vitro culture of midguts and an in vivo bioassay revealed that 20E and an ecdysteroid agonist halofenozide stimulated the expression of the three LdChSs. Conversely, a reduction of 20E by RNA interference (RNAi) of an ecdysteroidogenesis gene LdSHD repressed the expression of these LdChSs, and ingestion of halofenozide by LdSHD RNAi larvae rescued the repression. Moreover, disruption of 20E signaling by RNAi of LdEcR, LdE75, LdHR3, and LdFTZ‐F1 reduced the expression levels of these genes. Similarly, in vitro culture and an in vivo bioassay showed that exogenous JH and a JH analog methoprene activated the expression of the three LdChSs, whereas a decrease in JH by RNAi of a JH biosynthesis gene LdJHAMT downregulated these LdChSs. It seems that JH upregulates LdChSs at the early stage of each instar, whereas a 20E pulse triggers the transcription of LdChSs during molting in L. decemlineata.
    • Abstract: The immune deficiency (Imd) signaling pathway is activated by Gram‐negative bacteria for producing antimicrobial peptides (AMPs). In Drosophila melanogaster, the activation of this pathway is initiated by the recognition of Gram‐negative bacteria by peptidoglycan (PGN) recognition proteins (PGRPs), PGRP‐LC and PGRP‐LE. In this study, we found that the Imd pathway is involved in enhancing the promoter activity of AMP gene in response to Gram‐negative bacteria or diaminopimelic (DAP) type PGNs derived from Gram‐negative bacteria in an immune responsive silkworm cell line, Bm‐NIAS‐aff3. Using gene knockdown experiments, we further demonstrated that silkworm PGRP L6 (BmPGRP‐L6) is involved in the activation of E. coli or E. coli‐PGN mediated AMP promoter activation. Domain analysis revealed that BmPGRP‐L6 contained a conserved PGRP domain, transmembrane domain, and RIP homotypic interaction motif like motif but lacked signal peptide sequences. BmPGRP‐L6 overexpression enhances AMP promoter activity through the Imd pathway. BmPGRP‐L6 binds to DAP‐type PGNs, although it also binds to lysine‐type PGNs that activate another immune signal pathway, the Toll pathway in Drosophila. These results indicate that BmPGRP‐L6 is a key PGRP for activating the Imd pathway in immune responsive silkworm cells.
           PROTEASES FROM MIDGUT OF Mythimna separata Walker
    • Abstract: Two cDNA sequences encoding a trypsin‐like and a chymotrypsin‐like serine protease (MsT and MsCT, GenBank accession Nos. KP730443 and KP730444, respectively) were cloned from midgut of oriental armyworm, Mythimna separata Walker. Multiple alignments revealed that the deduced amino acid sequences of MsT and MsCT contained a serine protease catalytic motif GDSGGPL and catalytic triads (His, Asp, and Ser). Analyses of tissue and developmental expression of MsT and MsCT showed that they were mainly expressed in midguts and could be detected in first to sixth instar larvae, prepupal and pupal stages. Expressions of both MsT and MsCT were downregulated after 24 h of starvation and upregulated by subsequent insect refeeding. MsT expression in response to 20‐hydroxyecdysone (20E) was dose dependent and upregulated after 24 h. However, MsCT expression in response to 20E was downregulated compared with controls. MsCT, but not MsT, transcripts were upregulated after 24 h of Cry1Ac protoxin exposure. These results suggested that MsT was most likely involved in food protein digestion and molting in M. separata whereas MsCT was most likely involved in food protein digestion and Bacillus thuringiensis (Bt) protoxin activation. RNA interference indicated that MsT and MsCT expression levels decreased 76.7 and 86.2% after treated with MsT and MsCT dsRNA, respectively. This study showed that M. separata expressed midgut proteases in line with known lepidopteran counterparts and contributed valuable sequence resource information regarding insect proteases.
    • Abstract: Ecdysis in insects can be defined as shedding of the cuticle at the end of a larval stadium. This event can only occur after the peak titer of ecdysteroid in the hemolymph has returned to a low level. In the cockroach Periplaneta americana, ecdysis is strongly correlated with a rise in the concentration of trehalose and glucose in the hemolymph, leading to the idea that a causal relationship may exist between both events. The objective in this study was to determine if an increase in hemolymph sugar level would shorten the time to ecdysis in cockroach larvae with experimentally delayed ecdysis. The last larval stadium of P. americana averages 33.5 days but this increases significantly if the larva is injected with a small volume of saline. Injection of 10 μl of saline on day 20 and on four successive days lengthened the stadium by as much as 2 weeks. If, however, trehalose or glucose is incorporated into the saline, approximately 40% of the treated larvae undergo ecdysis at the same time as uninjected larvae. Injection of Peram‐AKH, the hypertrehalosemic hormone, also decreases the time for ecdysis to occur. This suggests that peak levels of ecdysteroid trigger the release of Peram‐AKH, which then leads to activation of trehalose synthesis. The results support the hypothesis that elevated hemolymph sugar is a contributing factor in the removal of ecdysteroid from the hemolymph.
    • Abstract: Vital physiological processes that drive the insect molt represent areas of interest for the development of alternative control strategies. The western tarnished plant bug (Lygus hesperus Knight) is a pest of numerous agronomic and horticultural crops but the development of novel control approaches is impeded by limited knowledge of the mechanisms regulating its molt. To address this deficiency, we examined the fundamental relationship underlying the hormonal and molecular components of ecdysis. At 27°C L. hesperus exhibits a temporally controlled nymph–adult molt that occurs about 4 days after the final nymph–nymph molt with ecdysteroid levels peaking 2 days prior to the final molt. Application of exogenous ecdysteroids when endogenous levels had decreased disrupted the nymphal–adult molt, with treated animals exhibiting an inability to escape the old exoskeleton and resulting in mortality compared to controls. Using accessible transcriptomic data, we identified 10 chitinase‐like sequences (LhCht), eight of which had protein motifs consistent with chitinases. Phylogenetic analyses revealed orthologous relationships to chitinases critical to molting in other insects. RT‐PCR based transcript profiling revealed that expression changes to four of the LhChts was coordinated with the molt period and ecdysteroid levels. Collectively, our results support a role for ecdysteroid regulation of the L. hesperus molt and suggest that cuticle clearance is mediated by LhCht orthologs of chitinases that are essential to the molt process. These results provide the initial hormonal and molecular basis for future studies to investigate the specific roles of these components in molting.
    • Abstract: Coexistence or displacement of parasitoids in hosts during intrinsic competitive interactions between different parasitoid species (multiparasitism) may depend on their life history traits and behavior. Intense competition for possession of hosts may lead to the elimination of the inferior competitor through physical attack and/or physiological suppression. However, the mechanisms of physiological suppression during multiparasitism remain unclear. Previous work has shown that first instar larvae of the solitary endoparasitoid Meteorus pulchricornis possess well‐developed mandibles that are used to kill competitors. Two gregarious endoparasitoids, Cotesia kariyai and C. rufricus, share host resources especially when the time gap of oviposition is short. Here, we investigated the physiological influence of wasp‐regulatory factors of the three endoparasitoids, M. pulchricornis, C. kariyai, and C. ruficrus, in their common host Mythimna separata. We found that MpVLP alone (or with venom) deleteriously affected the development of the two gregarious species. Similarly, CkPDV plus venom had toxic effect on M. pulchricornis eggs and immature larvae, although they were not harmful to immature stages of C. ruficrus. Cotesia kariyai and C. ruficrus were able to coexist mainly through the expression of regulatory factors and both could successfully emerge from a multiparasitized host. The injection of CkPDV plus venom after oviposition in L5 host larvae facilitated C. ruficrus development and increased the rate of successful parasitism from 9% to 62%. This suggests that the two gregarious parasitoid wasps exhibit strong phylogenetic affinity, favoring their coexistence and success in multiparasitized hosts.
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