Comparisons in temperature and photoperiodic-dependent diapause induction between domestic and wild mulberry silkworms.
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ABSTRACT:
SUBMITTER: Yokoyama T
PROVIDER: S-EPMC8044193 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:BackgroundBombyx mori was domesticated from the Chinese wild silkworm, Bombyx mandarina. Wild and domestic silkworms are good models in which to investigate genes related to silk protein synthesis that may be differentially expressed in silk glands, because their silk productions are very different. Here we used the mRNA deep sequencing (RNA-seq) approach to identify the differentially expressed genes (DEGs) in the transcriptomes of the median/posterior silk glands of two domestic and two wild silkworms.ResultsThe results indicated that about 58% of the total genes were expressed (reads per kilo bases per million reads (RPKM) ≥ 1) in each silkworm. Comparisons of the domestic and wild silkworm transcriptomes revealed 32 DEGs, of which 16 were up-regulated in the domestic silkworms compared with in the wild silkworms, and the other 16 were up-regulated in the wild silkworms compared with in the domestic silkworms. Quantitative real-time polymerase chain reaction (qPCR) was performed for 15 randomly selected DEGs in domestic versus wild silkworms. The qPCR results were mostly consistent with the expression levels determined from the RNA-seq data. Based on a Gene Ontology (GO) enrichment analysis and manual annotation, five of the up-regulated DEGs in the wild silkworms were predicted to be involved in immune response, and seven of the up-regulated DEGs were related to the GO term "oxidoreductase activity", which is associated with antioxidant systems. In the domestic silkworms, the up-regulated DEGs were related mainly to tissue development, secretion of proteins and metabolism.ConclusionsThe up-regulated DEGs in the two domestic silkworms may be involved mainly in the highly efficient biosynthesis and secretion of silk proteins, while the up-regulated DEGs in the two wild silkworms may play more important roles in tolerance to pathogens and environment adaptation. Our results provide a foundation for understanding the molecular mechanisms of the silk production difference between domestic and wild silkworms.
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Project description:Diapause, a programmed developmental arrest primarily induced by seasonal environmental changes, is very common in the animal kingdom, and found in vertebrates and invertebrates alike. Diapause provides an adaptive advantage to animals, as it increases the odds of surviving adverse conditions. In insects, individuals perceive photoperiodic cues and modify endocrine signaling to direct reproductive diapause traits, such as ovary arrest and increased fat accumulation. However, it remains unclear as to which endocrine factors are involved in this process and how they regulate the onset of reproductive diapause. Here, we found that the long day-mediated drop in the concentration of the steroid hormone ecdysone is essential for the preparation of photoperiodic reproductive diapause in Colaphellus bowringi, an economically important cabbage beetle. The diapause-inducing long-day condition reduced the expression of ecdysone biosynthetic genes, explaining the drop in the titer of 20-hydroxyecdysone (20E, the active form of ecdysone) in female adults. Application of exogenous 20E induced vitellogenesis and ovarian development but reduced fat accumulation in the diapause-destined females. Knocking down the ecdysone receptor (EcR) in females destined for reproduction blocked reproductive development and induced diapause traits. RNA-seq and hormone measurements indicated that 20E stimulates the production of juvenile hormone (JH), a key endocrine factor in reproductive diapause. To verify this, we depleted three ecdysone biosynthetic enzymes via RNAi, which confirmed that 20E is critical for JH biosynthesis and reproductive diapause. Importantly, impairing Met function, a component of the JH intracellular receptor, partially blocked the 20E-regulated reproductive diapause preparation, indicating that 20E regulates reproductive diapause in both JH-dependent and -independent manners. Finally, we found that 20E deficiency decreased ecdysis-triggering hormone signaling and reduced JH production, thereby inducing diapause. Together, these results suggest that 20E signaling is a pivotal regulator that coordinates reproductive plasticity in response to environmental inputs.
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Project description:BACKGROUND: Most organisms have evolved a circadian clock in order to anticipate daily environmental changes and many of these organisms are also capable of sophisticated measurement of daylength (photoperiodism) that is used to regulate seasonal events such as diapause, migration and polymorphism. It has been generally accepted that the same elements are involved in both circadian (daily) and seasonal (annual) rhythms because both rely upon daily light-dark cycles. However, as reasonable as this sounds, there remains no conclusive evidence of such a molecular machinery in insects. We have approached this issue by using RNA interference (RNAi) in Riptortus pedestris. RESULTS: The cuticle deposition rhythm exhibited the major properties of circadian rhythms, indicating that the rhythm is regulated by a circadian clock. RNAi directed against the circadian clock genes of period and cycle, which are negative and positive regulators in the circadian clock, respectively, disrupted the cuticle deposition rhythm and distinct cuticle layers were produced by these RNAi. Simultaneously, period RNAi caused the insect to avert diapause under a diapause-inducing photoperiod whereas cycle RNAi induced diapause under a diapause-averting photoperiod. The expression patterns of juvenile hormone-regulated genes and the application of juvenile hormone analogue suggested that neither ovarian development itself nor a downstream cascade of juvenile hormone secretion, were disturbed by period and cycle RNAi. CONCLUSIONS: This study revealed that the circadian clock genes are crucial not only for daily rhythms but also for photoperiodic diapause. RNAi directed against period and cycle had opposite effects not only in the circadian cuticle deposition rhythm but also in the photoperiodic diapause. These RNAi also had opposite effects on juvenile hormone-regulated gene expression. It is still possible that the circadian clock genes pleiotropically affect ovarian development but, based on these results, we suggest that the circadian clock operated by the circadian clock genes, period and cycle, governs seasonal timing as well as the daily rhythms.
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Project description:Metabonomics accurately monitors the precise metabolic responses to various dietary patterns. Metabolic profiling allows simultaneous measurement of various fecal metabolites whose concentrations may be affected by food intake. In this study, we analyzed the fecal metabolomes of silkworm (Bombyx mori) larvae reared on fresh mulberry leaves and artificial diets. 57 differentially expressed metabolites were identified by gas chromatography-mass spectrometry. Of these, 39 were up-regulated and 18 were downregulated in the mulberry leaf meal group. Most of the amino acids, carbohydrates and lipids associated with physical development and silk protein biosynthesis were enriched in silkworms reared on mulberry leaves. In contrast, the urea, citric acid, D-pinitol, D-(+)-cellobiose and N-acetyl glucosamine levels were relatively higher in the silkworm feeding on the artificial diets. The findings of this study help clarify the association between diet and metabolic profiling.
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Project description:Understanding mechanisms that promote the maintenance of biodiversity (genetic and species diversity) has been a central topic in evolution and ecology. Previous studies have revealed that diapause can contribute to coexistence of competing genotypes or species in fluctuating environments via the storage effect. However, they tended to focus on differences in reproductive success (e.g. seed yield) and diapause termination (e.g. germination) timing. Here we tested whether different photoperiodic responses in diapause induction can promote coexistence of two parthenogenetic (asexual) genotypes of Daphnia pulex in Lake Fukami-ike, Japan. Through laboratory experiments, we confirmed that short day length and low food availability induced the production of diapausing eggs. Furthermore, we found that one genotype tended to produce diapausing eggs in broader environmental conditions than the other. Terminating parthenogenetic reproduction earlier decreases total clonal production, but the early diapausing genotype becomes advantageous by assuring reproduction in 'short' years where winter arrival is earlier than usual. Empirically parameterized theoretical analyses suggested that different photoperiodic responses can promote coexistence via the storage effect with fluctuations of the growing season length. Therefore, timing of diapause induction may be as important as diapause termination timing for promoting the maintenance of genetic diversity in fluctuating environments.
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Project description:Photoperiod is one of the most reliable environmental cues for plants to regulate flowering timing. In Arabidopsis thaliana, CONSTANS (CO) transcription factor plays a central role in regulating photoperiodic flowering. In contrast to posttranslational regulation of CO protein, still little was known about CO transcriptional regulation. Here we show that the CINCINNATA (CIN) clade of class II TEOSINTE BRANCHED 1/ CYCLOIDEA/ PROLIFERATING CELL NUCLEAR ANTIGEN FACTOR (TCP) proteins act as CO activators. Our yeast one-hybrid analysis revealed that class II CIN-TCPs, including TCP4, bind to the CO promoter. TCP4 induces CO expression around dusk by directly associating with the CO promoter in vivo. In addition, TCP4 binds to another flowering regulator, GIGANTEA (GI), in the nucleus, and induces CO expression in a GI-dependent manner. The physical association of TCP4 with the CO promoter was reduced in the gi mutant, suggesting that GI may enhance the DNA-binding ability of TCP4. Our tandem affinity purification coupled with mass spectrometry (TAP-MS) analysis identified all class II CIN-TCPs as the components of the in vivo TCP4 complex, and the gi mutant did not alter the composition of the TCP4 complex. Taken together, our results demonstrate a novel function of CIN-TCPs as photoperiodic flowering regulators, which may contribute to coordinating plant development with flowering regulation.
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Project description:Silkworm, Bombyx mori L., research involves studies on improving strains for enhanced sustainability of high-quality silk production. Several of these have investigated the factors affecting growth and development of silkworm larvae and cocoon characteristics that subsequently affect the yield and quality of silk. The gut microbiota has been reported to impact growth and development of silkworms and has been linked, in particular, with absorption and utilization of nutrients and immunity to diseases. The silkworm strains maintained in the Philippines lack sufficient biological data for use in strain improvement. This prompted efforts to augment the data by profiling bacterial communities through high-throughput 16S rRNA gene amplicon sequencing and analysis in four of the local silkworm strains that are bred and maintained in the country. Results of the study showed that the four silkworm strains are abundant in bacteria that belong to the genera Pseudomonas, Sphingomonas, Delftia, Methylobacterium and Acinetobacter. Results also showed that bacterial diversity and evenness increase as larvae mature, which can be correlated to larval development and shifts in the amount and age of mulberry leaves the larvae consume.
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Project description:Silkworms (Bombyx mori) reared on artificial diets have great potential applications in sericulture. However, the mechanisms underlying the enhancement of metabolic utilization by altering silkworm nutrition are unclear. The aim of this study was to investigate the mechanisms responsible for the poor development and low silk protein synthesis efficiency of silkworms fed artificial diets. After multi-generational selection of the ingestive behavior of silkworms to artificial diets, we obtained two strains, one of which developed well and another in which almost all its larvae starved to death on the artificial diets. Subsequently, we analyzed the metabolomics of larval hemolymph by gas chromatography/liquid chromatography-mass spectrometry, and the results showed that vitamins were in critically short supply, whereas the nitrogen metabolic end product of urea and uric acid were enriched substantially, in the hemolymph of the silkworms reared on the artificial diets. Meanwhile, amino acid metabolic disorders, as well as downregulation of carbohydrate metabolism, energy metabolism, and lipid metabolism, co-occurred. Furthermore, 10 male-dominant metabolites and 27 diet-related metabolites that differed between male and female silkworms were identified. These findings provide important insights into the regulation of silkworm metabolism and silk protein synthesis when silkworms adapt to an artificial diet.
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Project description:Diapause is a programmed dormancy that allows organisms to tolerate predictable periods of unfavourable conditions by temporarily halting development and reducing metabolism. Diapause is widespread amongst insects and is crucial for allowing organisms to coordinate their growth and reproduction with favourable environmental conditions. Although the adaptive significance of diapause is well understood, the molecular mechanisms underpinning diapause remain unresolved. We performed high-throughput sequencing to investigate the role of microRNAs (miRNAs) in the diapause of the Asian tiger mosquito, Aedes albopictus. We first investigated miRNAs in diapause induction by characterizing maternally provisioned miRNAs in mature oocytes of Ae. albopictus under diapause-inducing and diapause-averting conditions. Second, we investigated miRNAs in diapause maintenance by characterizing miRNAs in diapause and nondiapause pharate larvae. We identified 162 miRNAs, 152 previously known and 10 putatively novel. We identified no differentially abundant miRNAs in mature oocytes and seven differentially abundant miRNAs in pharate larvae. The predicted targets of differentially abundant miRNAs include genes affecting several processes related to diapause maintenance including ecdysone regulation, immune response, lipid metabolism and regulation of development. Our results suggest that Ae. albopictus does not maternally provision a unique set of miRNAs during diapause induction but miRNAs are a component of diapause maintenance in this species.
| S-EPMC5673581 | biostudies-literature
Project description:The mechanisms that integrate environmental signals into developmental programs remain largely uncharacterized. Nuclear receptors (NRs) are ligand-regulated transcription factors that orchestrate the expression of complex phenotypes. The vitamin D receptor (VDR) is an NR activated by 1α,25-dihydroxyvitamin D3 [1,25(OH)2D3], a hormone derived from 7-dehydrocholesterol (7-DHC). VDR signaling is best known for regulating calcium homeostasis in mammals, but recent evidence suggests a diversity of uncharacterized roles. In response to incubation temperature, embryos of the annual killifish Austrofundulus limnaeus can develop along two alternative trajectories: active development and diapause. These trajectories diverge early in development, from a biochemical, morphological, and physiological perspective. We manipulated incubation temperature to induce the two trajectories and profiled changes in gene expression using RNA sequencing and weighted gene coexpression network analysis. We report that transcripts involved in 1,25(OH)2D3 synthesis and signaling are expressed in a trajectory-specific manner. Furthermore, exposure of embryos to vitamin D3 analogs and Δ4-dafachronic acid directs continuous development under diapause-inducing conditions. Conversely, blocking synthesis of 1,25(OH)2D3 induces diapause in A. limnaeus and a diapause-like state in zebrafish, suggesting vitamin D signaling is critical for normal vertebrate development. These data support vitamin D signaling as a molecular pathway that can regulate developmental trajectory and metabolic dormancy in a vertebrate. Interestingly, the VDR is homologous to the daf-12 and ecdysone NRs that regulate dormancy in Caenorhabditis elegans and Drosophila We suggest that 7-DHC-derived hormones and their associated NRs represent a conserved pathway for the integration of environmental information into developmental programs associated with life history transitions in animals.
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