查看更多>>摘要：After a millennium of domestication,numerous silkworm mutants have emerged that exhibit transparent epidermis,which is caused by abnormally low levels of uric acid.We identified the Bombyx mori gene Bmcap(BMSK0003832)as the homolog of cappuccino,a subunit of the biogenesis of lysosome-related organelles complex-1(BLOC-1)that has been extensively characterized in human,mouse,and insect species,by analyzing the amino acid sequences of putative purine metabolism genes.Using the clustered regularly interspaced palindromic repeats(CRISPR)/CRISPR-associated pro-tein 9 system,we disrupted Bmcap,resulting in decreased uric acid levels in the silkworm epidermis and a translucent skin phenotype.In the Bmcap mutant,the purine metabolism,nitrogen metabolism,pyrimidine metabolism,and membrane system were altered com-pared to the wild type.Biogenesis of lysosome-related organelle complex genes play a role in the pigmentation and biogenesis of lysosome-related organelles(LROs)in platelets,melanocytes,and megakaryocytes.LROs exhibit unique morphologies and functions in various tissues and cells.Investigation of the Bmcap mutant will enhance our understand-ing of the uric acid metabolic pathway in silkworms,and this mutant offers a valuable silkworm model for LRO studies.
查看更多>>摘要：Apoptosis is an important process for organism development that functions to eliminate cell damage,maintain homeostasis,and remove obsolete tissues during morpho-genesis.In mammals,apoptosis is accompanied by the release of cytochrome C(Cyt-c)from mitochondria to the cytoplasm.However,whether this process is conserved in the fruit fly,Drosophila melanogaster,remains controversial.In this study,we discovered that during the degradation of Drosophila salivary gland,the transcription of mitochondria apoptosis factors(MAPFs),Cyt-c,and death-associated APAF1-related killer(Dark)en-coding genes are all upregulated antecedent to initiator and effector caspases encoding genes.The proteins Cyt-c and the active caspase 3 appear gradually in the cytoplasm dur-ing salivary gland degradation.Meanwhile,the Cyt-c protein colocates with mito-GFP,the marker indicating cytoplasmic mitochondria,and the change in mitochondrial membrane potential coincides with the appearance of Cyt-c in the cytoplasm.Moreover,impeding or promoting 20E-induced transcription factor E93 suppresses or enhances the staining of Cyt-c and the active caspase 3 in the cytoplasm of salivary gland,and accordingly de-creases or increases the mitochondrial membrane potential,respectively.Our research pro-vides evidence that cytoplasmic Cyt-c appears before apoptosis during Drosophila salivary gland degradation,shedding light on partial conserved mechanism in apoptosis between insects and mammals.
查看更多>>摘要：Pheromone receptors(PRs)are key proteins in the molecular mechanism of pheromone recognition,and exploring the functional differentiation of PRs between closely related species helps to understand the evolution of moth mating systems.Pheromone components of the agricultural pest Mythimna loreyi have turned into(Z)-9-tetradecen-l-yl acetate(Z9-14:OAc),(Z)-7-dodecen-l-yl acetate(Z7-12:OAc),and(Z)-11-hexadecen-l-yl acetate,while the composition differs from that of M.separata in the genus Mythimna.To understand the molecular mechanism of pheromone recognition,we sequenced and analyzed antennal transcriptomes to identify 62 odorant receptor(OR)genes.The expression levels of all putative ORs were analyzed using differentially ex-pressed gene analysis.Six candidate PRs were quantified and functionally characterized in the Xenopus oocytes system.MlorPR6 and MlorPR3 were determined to be the recep-tors of major and minor components Z9-14:OAc and Z7-12:OAc.MlorPR1 and female antennae(FA)-biased MlorPR5 both possessed the ability to detect pheromones of sym-patric species,including(Z,E)-9,12-tetradecadien-l-ol,(Z)-9-tetradecen-l-ol,and(Z)-9-tetradecenal.Based on the comparison of PR functions between M.loreyi and M.sep-arata,we analyzed the differentiation of pheromone recognition mechanisms during the evolution of the mating systems of 2 Mythimna species.
查看更多>>摘要：Reproduction is of great importance for the continuation of the species.In in-sects,the fat body is the major tissue for nutrient storage and involved in vitellogenesis,which is essential for female reproduction.Here,2 proteins,hexamerin and allergen,were separated from the fat bodies of adult female American cockroaches(Periplaneta amer-icana)and identified as storage proteins,encoding for 733 amino acids with molecular weight of 87.88 kDa and 686 amino acids with molecular weight of 82.18 kDa,respec-tively.The encoding genes of these 2 storage proteins are mainly expressed in the fat body.RNA interference-mediated knockdown of Hexamerin and Allergen in the early stage of the first reproductive cycle in females suppressed vitellogenesis and ovarian maturation,indicating that these storage proteins are involved in controlling reproduction.Importantly,the expression of Hexamerin and Allergen was repressed by knockdown of the juvenile hormone(JH)receptor gene Met and the primary response gene Kr-hl,and was induced by methoprene,a JH analog,in both in vivo and in vitro experiments.Altogether,we have determined that hexamerin and allergen are identified as storage proteins and play an im-portant role in promoting female reproduction in the American cockroach.The expression of their encoding genes is induced by JH signaling.Our data reveal a novel mechanism by which hexamerin and allergen are necessary for JH-stimulated female reproduction.
查看更多>>摘要：Termite queens and kings live longer than nonreproductive workers.Several molecular mechanisms contributing to their long lifespan have been investigated;however,the underlying biochemical explanation remains unclear.Coenzyme Q(CoQ),a compo-nent of the mitochondrial electron transport chain,plays an essential role in the lipophilic antioxidant defense system.Its beneficial effects on health and longevity have been well studied in several organisms.Herein,we demonstrated that long-lived termite queens have significantly higher levels of the lipophilic antioxidant CoQ10 than workers.Liquid chro-matography analysis revealed that the levels of the reduced form of CoQ10 were 4 fold higher in the queen's body than in the worker's body.In addition,queens showed 7 fold higher levels of vitamin E,which plays a role in antilipid peroxidation along with CoQ,than workers.Furthermore,the oral administration of CoQ10 to termites increased the CoQ10 redox state in the body and their survival rate under oxidative stress.These find-ings suggest that CoQ10 acts as an efficient lipophilic antioxidant along with vitamin E in long-lived termite queens.This study provides essential biochemical and evolutionary in-sights into the relationship between CoQ10 concentrations and termite lifespan extension.
查看更多>>摘要：Entomopathogenic fungi are protected by a cell wall with dynamic structure for adapting to various environmental conditions.β-1,3-Glucan recognition proteins activate the innate immune system of insects by recognizing surface molecules of fungi.However,the associations between pathogenicity and the different components of entomopathogenic fungal cell walls remain unclear.Three Beauveria bassiana strains were selected that have significantly differing virulence against Bombyx mori.The molecular mechanisms under-lying the immune response in B.mori were investigated using RNA sequencing,which revealed differences in the immune response to different B.bassiana strains at 12 h post-infection.Immunofluorescence assays revealed that β-1,3-glucan content had an opposite trend to that of fungal virulence.β-1,3-Glucan injection upregulated BmβGRP4 expres-sion and significantly reduced the virulence of the high-virulence strain but not that of the medium-virulence or low-virulence strains.BmβGRP4 silencing in B.mori with RNA interference resulted in the opposite virulence pattern,indicating that the virulence of B.bassiana was affected by the cell walls'content of β-1,3-glucan,which could be recog-nized by BmβGRP4.Furthermore,interference with the gene CnA(calcineurin catalytic A subunit)involved in β-1,3-glucan synthesis eliminated differences in virulence between B.bassiana strains.These results indicate that strains of a single species of pathogenic fungi that have differing cell wall components are recognized differently by the innate immune system of B.mori.
查看更多>>摘要：Bark beetles are an economically and ecologically important insect group,with aggregation behavior and thus host colonization success depends on pheromone-mediated communication.For some species,such as the major invasive forest pest in China,red tur-pentine beetle(Dendroctonus valens),gut microbiota participates in pheromone produc-tion by converting tree monoterpenes into pheromone products.However,how variation in gut microenvironment,such as pH,affects the gut microbial composition,and conse-quently pheromone production,is unknown.In this study,we fed wild caught D.valens with 3 different pH media(main host diet with natural pH of 4.7;a mildly acidic diet with pH 6 mimicking the beetle gut pH;and highly acidic diet with pH 4),and measured their effects on the gut pH,bacterial community and production of the main aggregation and anti-aggregation pheromone(verbenone).We further tested the verbenone production capacity of 2 gut bacterial isolates in different pH environments(pH 6 and 4).Compared to natural state or main host diet,feeding on less acidic diet(pH 6)diluted the acidity of the gut,whereas feeding on highly acidic diet(pH 4)enhanced it.Both changes in gut pH reduced the abundance of dominant bacterial genera,resulting in decreased verbenone production.Similarly,the highest pheromone conversion rate of the bacterial isolates was observed in pH mimicking the acidity in beetle gut.Taken together,these results indicate that changes in gut pH can affect gut microbiota composition and pheromone production,and may therefore have the potential to affect host colonization behavior.
查看更多>>摘要：In a tritrophic context of plant-insect-entomopathogen,plants play important roles in modulating the interaction of insects and their pathogenic viruses.Currently,the influence of plants on the transmission of insect viruses has been mainly studied on bac-uloviruses and some RNA viruses,whereas the impact of plants on other insect viruses is largely unknown.Here,we identified a new densovirus infecting the green peach aphid Myzus persicae and tested whether and how host plants influence the transmission of the aphid densovirus.The complete single-stranded DNA genome of the virus,M.persicae densovirus 2,is 5 727 nt and contains inverted terminal repeats.Transcription and phy-logenetic analysis indicated that the virus was distinct from other a few identified aphid densoviruses.The virus abundance was detected highly in the intestinal tract of aphids,compared with the lower level of it in other tissues including head,embryo,and epidermis.Cabbage and pepper plants had no obvious effect on the vertical transmission and saliva-mediated horizontal transmission of the virus.However,the honeydew-mediated horizon-tal transmission among aphids highly depended on host plants(65％on cabbages versus 17％on peppers).Although the virus concentration in the honeydew produced by aphids between 2 plants was similar,the honeydew production of the infected aphids reared on peppers was dramatically reduced.Taken together,our results provide evidence that plants influence the horizontal transmission of a new densovirus in an aphid population by mod-ulating honeydew secretion of aphids,suggesting plants may manipulate the spread of an aphid-pathogenic densovirus in nature.
查看更多>>摘要：Sap-sucking insects often transmit plant viruses but also carry insect viruses,which infect insects but not plants.The impact of such insect viruses on insect host biology and ecology is largely unknown.Here,we identified a novel insect-specific virus carried by brown citrus aphid(Aphis citricidus),which we tentatively named Aphis citricidus pi-cornavirus(AcPV).Phylogenetic analysis discovered a monophyletic cluster with AcPV and other unassigned viruses,suggesting that these viruses represent a new family in order Picornavirales.Systemic infection with AcPV triggered aphid antiviral immunity medi-ated by RNA interference,resulting in asymptomatic tolerance.Importantly,we found that AcPV was transmitted horizontally by secretion of the salivary gland into the feeding sites of plants.AcPV influenced aphid stylet behavior during feeding and increased the time required for intercellular penetration,thus promoting its transmission among aphids with plants as an intermediate site.The gene expression results suggested that this mech-anism was linked with transcription of salivary protein genes and plant defense hormone signaling.Together,our results show that the horizontal transmission of AcPV in brown citrus aphids evolved in a manner similar to that of the circulative transmission of plant viruses by insect vectors,thus providing a new ecological perspective on the activity of insect-specific viruses found in aphids and improving the understanding of insect virus ecology.
查看更多>>摘要：Movement is an important animal behavior contributing to reproduction and survival.Animal movement is often examined in arenas or enclosures under laboratory conditions.We used the red flour beetle(Tribolium castaneum)to examine here the effect of the arena size,shape,number of barriers,access to the arena's center,and illumina-tion on six movement properties.We demonstrate great differences among arenas.For example,the beetles moved over longer distances in clear arenas than in obstructed ones.Movement along the arena's perimeter was greater in smaller arenas than in larger ones.Movement was more directional in round arenas than in rectangular ones.In general,the beetles stopped moving closer to the perimeter and closer to corners(in the square and rectangular arenas)than expected by chance.In some cases,the arena properties inter-acted with the beetle sex to affect several movement properties.All these suggest that arena properties might also interact with experimental manipulations to affect the out-come of studies and lead to results specific to the arena used.In other words,instead of examining animal movement,we in fact examine the animal interaction with the arena structure.Caution is therefore advised in interpreting the results of studies on movement in arenas under laboratory conditions and we recommend paying attention also to barri-ers or obstacles in field experiments.For instance,movement along the arena's perimeter is often interpreted as centrophobism or thigmotaxis but the results here show that such movement is arena dependent.
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