摘要: In insects, the juvenile hormone (JH) and 20-hydroxyecdysone (20E) pathways jointly regulate fecundity, but only methyl farnesoate (MF) and ponasterone A exist in mites. Comparative transcriptomic analysis in Panonychus citri showed that E75B was significantly downregulated when exposed to lufenuron. Knockdown of E75B significantly affects the expression of vitellogenin (Vg), Fushi tarazu factor 1 (Ftz-f1) and juvenile hormone acid O-methyltransferase (JHAMT), reducing fecundity in mites. The knockdown of Ftz-f1 produced a more significant effect than the knockdown of E75B, indicating that the ponasterone A pathway positively regulates fecundity in P. citri. After the knockdown of JHAMT, the expression levels of both Vg and Ftz-f1 and fecundity were significantly increased, along with the inhibition of Kr-h1, suggesting that JHAMT was negatively correlated with fecundity in the regulatory network. Knockdown of Kr-h1 inhibited the expression of Vg and Ftz-f1 and fecundity, and whether the drop in fecundity is caused by Kr-h1 or Ftz-f1 is unclear. Subsequent feeding with MF induced Kr-h1 and Vg expression, whereas no significant effects were observed for JHAMT and Ftz-f1. Therefore, the MF pathway stimulates fecundity independently. RNA interference (RNAi) showed that JHAMT and Ftz-f1 inhibited each other, resulting in opposite effects of MF and ponasterone A pathways on steady-state fecundity when either factor changed. Meanwhile, JHAMT knockdown led to increased fecundity, indicating that the stimulating effect of the ponasterone A pathway was greater than the inhibiting effect of the MF pathway, and demonstrating the dominant role of the ponasterone A pathway. Therefore, the interaction between JHAMT and Ftz-f1 may be closely associated with the maintenance of MF-ponasterone A regulatory network homeostasis and is involved in the reduction of fecundity in P. citri induced by exposure to lufenuron.

摘要: In addition to preventing precocious larval metamorphosis, juvenile hormone (JH), synthesized in corpora allata (CA), is known to stimulate female reproduction of insects. JH titer is extremely low or absent during metamorphosis, but thereafter rapidly increases in the previtellogenic stage and rises to a peak in the vitellogenic phase. However, the mechanisms underlying the biosynthesis of high levels of JH in adults remain unclear. We found in this study that 12 genes involved in JH synthesis pathway were highly expressed in the CA of adult locusts. By transcriptome analysis and quantitative real-time - polymerase chain reaction validation, a total of 106 evolutionary conserved micro RNAs (miRNAs) and 163 species-specific miRNAs were identified in locust CA. Dual-luciferase assay revealed that 17 miRNAs bound to 10 JH synthesis genes (JHSGs) and downregulated their expression. These miRNAs were expressed in low levels during vitellogenic stage, which was oppositive from that of targeting JHSGs. Six miRNAs including miR-971-3p, miR-31a, miR-9-5p, miR-1-3p, miR-315, and miR-282 were selected for function study. Co-application of agomiRs resulted in significantly decreased levels of targeting JHSGs, accompanied by significantly reduced vitellogenin expression as well as arrested ovarian development. The data suggest that multiple miRNAs expressed synchronously at low levels in the vitellogenic phase, thereby ensuring the high levels of JHSG expression to facilitate JH biosynthesis required for JH-dependent female reproduction. The findings provide important information for deciphering miRNA-messenger RNA modules for JH biosynthesis as well as JH regulation of insect metamorphosis and reproduction.

摘要: Hemiptera is one of the most significant orders of insect pests, including whiteflies, true bugs, aphids, planthoppers, psyllids, and so forth, which have led to substantial economic losses in agricultural industries and have significantly affected food yields through their ability to suck the phloem sap of crops and transmit numerous bacterial and viral pathogens. Therefore, explorations of pest-specific, eco-friendly and easy-to-adopt technologies for hemipteran pest control are urgently needed. To the best of our knowledge, microRNAs (miRNAs), which are endogenous non-coding small RNAs approximately 22 nucleotides in length, are involved in regulating gene expression via the direct recognition and binding of the 3 '-untranslated region (3 '-UTR) of target messenger RNAs (mRNAs) or by acting as a center of a competitive endogenous RNA (ceRNA) network at the post-transcriptional level. This review systematically outlines the characterization and functional investigation of the miRNA biogenesis pathway in hemipteran pests, such as whiteflies, true bugs, aphids and planthoppers. In addition, we explored the results of small RNA sequencing and functional observations of miRNAs in these pests, and the results suggest that the numerous miRNAs obtained and annotated via high-throughput sequencing technology and bioinformatic analyses contribute to molting development, fitness, wing polyphenism, symbiont interactions and insecticide resistance in hemipteran pests. Finally, we summarize current advances and propose a framework for future research to extend the current data and address potential limitations in the investigation and application of hemipteran miRNAs.

摘要: Grass carp reovirus (GCRV)-induced gene 1 (Gig1) is identified initially in crucian carp C. auratus as a novel interferon-stimulated gene (ISG) encoding an antiviral protein and subsequently as the founder member of Gig1 gene family. However, the evolution and function of Gig1 family members remain largely unknown. In this study, genome-wide searchs of 100 vertebrate species representing the main taxonomic lineages revealed that the Gig1 family originated from a common ancestor of bony fish but was completely lost in tetrapods. The Gig1 family is divided into three subfamilies, each with its own characteristics in gain and loss. Compared to subfamily I that originated the earliest and showed no significant change in gene copies, subfamilies II and III were expanded robustly with teleost radiation. Despite no known domains having been identified, motif prediction revealed a conserved motif arrangement in all Gig1 family proteins. Functionally, both zebrafish and grass carp have subfamilies I and II but not subfamily III. However, only certain subfamily II genes were highly induced by viral infection and thus capable of inhibiting viral replication by overexpression and knockout assays. The Japanese rice fish medaka has no subfamily II and, strikingly, one subfamily III gene acquired antiviral feature. Site-directed mutation showed that three leucine residues conserved in the motif 1 were essential for the antiviral role of subfamily II genes in zebrafish. In summary, our results indicate that bony fish-specific Gig1 gene family has been undergoing diversification in expression and function toward virus infection in a given species.

摘要: The Insulin-like Growth Factor Binding Protein (IGFBP) family genes, which function as carrier proteins in the circulation, are integral to various physiological processes such as growth, metabolism, reproduction, and stress responses. However, the systematic identification, characterization, and functional analysis of igfbp family genes in teleosts remain to be explored. In this study, we identified and characterized a total of 11 IGFBP family members in the Leopard Coral Grouper (Plectropomus leopardus). Expression analysis revealed that igfbp genes exhibit tissue-specific expression patterns in adult P. leopardus. Notably, certain igfbp genes were differentially expressed in growth-related tissues in fast-growing versus slow-growing individuals, suggesting their potential role in growth regulation. Specifically, the expression of igfbp2a and igfbp2b in the liver was further validated using FISH. Furthermore, knockdown of igfbp2b expressed specifically in the liver resulted in the promotion of muscle development and increased expressions related to muscle cell development. Additionally, several igfbp genes were dynamically involved in the response to acute hypothermia in the brain, gills, kidneys, and liver. These findings offer a comprehensive understanding of the characteristics and functions of igfbp family genes in P. leopardus, providing a solid foundation for further investigation into the functional mechanisms of igfbp genes in teleosts.