摘要: Trehalose-6-phosphate synthase (TPS), an enzyme that hydrolyzes two glucose molecules to yield trehalose, plays a pivotal role in various physiological processes. In this study, we cloned the trehalose-6-phosphate synthase gene (HvTPS) and investigated its expression patterns in various tissues and developmental stages in Heortia vitessoides Moore (Lepidoptera: Crambidae). HvTPS was highly expressed in the fat body and after pupation or before molting. We knocked down TPS in H. vitessoides by RNA interference and found that 3.0 mu g of dsHvTPS resulted in optimal interference at 24 h and 36 h post-injection and caused a sharp decline in the survival rate during the 5th instar larval-pupal stage and obviously abnormal or lethal phenotypes. Additionally, compared to the controls, TPS activity and trehalose contents were significantly lower and the glucose content was significantly higher 24 h or 36 h after injection with 3.0 mu g of dsHvTPS. Furthermore, the silencing of HvTPS suppressed the expression of six key genes in the chitin biosynthesis pathway and one key gene related to lipid catabolism. The expression levels of two genes associated with lipid biosynthesis were upregulated. These results strongly suggest that HvTPS is essential for the normal growth and development of H. vitessoides and provide a reference for further studies of the utility of key genes involved in chitin and lipid biosynthesis for controlling insect development.

摘要: Wings are essential for insect fitness. A number of proteins and enzymes have been identified to be involved in wing terminal differentiation, which is characterized by the formation of the wing cuticle. Here, we addressed the question whether chitinase 10 (Cht10) may play an important role in chitin organization in the wings of the fruit flyDrosophila melanogaster. Initially, we first found thatCht10expression coincides with the expression of the chitin synthase coding genekkv. This suggests that the respective proteins may cooperate during wing differentiation. In tissue-specific RNA interference experiments, we demonstrate that suppression ofCht10causes an excess in chitin amounts in the wing cuticle. Chitin organization is severely disrupted in these wings. Based on these data, we hypothesize that Cht10 restricts chitin amounts produced by Kkv in order to ensure normal chitin organization and wing cuticle formation. In addition, we found by scanning electron microscopy thatCht10suppression also affects the cuticle surface. In turn, cuticle inward permeability is enhanced inCht10-less wings. Moreover, flies with reduced Cht10 function are unable to fly. In conclusion,Cht10is essential for wing terminal differentiation and function.

摘要: Eusocial insects display a caste system in which different castes are morphologically and physiologically specialized for different tasks. Recent studies have revealed that epigenetic modifications, including DNA methylation and histone modification, mediate caste determination and differentiation, longevity, and polyethism in eusocial insects. Although there has been a growing interest in the relationship between epigenetic mechanisms and phenotypic plasticity in termites, there is little information about differential expression levels among castes and expression sites for these genes in termites. Here we show royal-tissue-specific expression of epigenetic modification genes in the termite Reticulitermes speratus. Using RNA-seq, we identified 74 genes, including three DNA methyltransferases, seven sirtuins, 48 Trithorax group proteins, and 16 Polycomb group proteins. Among these genes, 15 showed king-specific expression, and 52 showed age-dependent differential expression in kings and queens. Quantitative real-time PCR revealed that DNA methyltransferase 3 is expressed specifically in the king's testis and fat body, whereas some histone modification genes are remarkably expressed in the king's testis and queen's ovary. These findings imply that epigenetic modification plays important roles in the gamete production process in termite kings and queens.

摘要: During insect larval-pupal metamorphosis, proteins in the hemolymph are absorbed by the fat body for the maintenance of intracellular homeostasis; however, the type of proteins and how these proteins are internalized into the fat body are unclear. In Bombyx mori, the developmental profiles of total proteins in the hemolymph and fat body showed that hemolymph-decreased protein bands (55-100 kDa) were in accordance with those protein bands that increased in the fat body. Inhibition of clathrin-dependent endocytosis predominantly blocked the transportation of 55-100 kDa proteins from the hemolymph into the fat body, which was further verified by RNA interference treatment of Bmclathrin. Six hexamerins were shown to comprise similar to 90% of the total identified proteins in both the hemolymph and fat body by mass spectrum (MS) analysis. In addition, hemolymph-specific proteins were mainly involved in material transportation, while fat body-specific proteins particularly participated in metabolism. In this paper, four hexamerins were found for the first time, and potential proteins absorbed by the fat body from the hemolymph through clathrin-dependent endocytosis were identified. This study sheds light on the protein absorption mechanism during insect metamorphosis.

摘要: The Junonia coenia densovirus rapidly traverses the gut epithelium of the host lepidopteran without replicating in the gut cells. The ability of this virus to transcytose across the gut epithelium is of interest for the potential use of virus structural proteins as delivery vehicles for insecticidal peptides that act within the insect hemocoel, rather than in the gut. In this study, we used fall armyworm, Spodoptera frugiperda to examine the binding of the virus to brush border membrane vesicle proteins by two-dimensional ligand blot analysis. We also assessed the rate of flux of the primary viral structural protein, VP4 fused to eGFP with a proline-rich linker (VP4-P-eGFP) through the gut epithelium ex vivo in an Ussing chamber. The mechanisms involved with transcytosis of VP4-P-eGFP were assessed by use of inhibitors. Bovine serum albumin (BSA) and eGFP were used as positive and negative control proteins, respectively. In contrast to BSA, which binds to multiple proteins on the brush border membrane, VP4-P-eGFP binding was specific to a protein of high molecular mass. Protein flux was significantly higher for VP4-P-eGFP after 2 h than for albumin or eGFP, with rapid transcytosis of VP4-P-eGFP within the first 30 min. In contrast to BSA which transcytosed following clathrin-mediated endocytosis, the movement of VP4-P-eGFP was vesicle-mediated but clathrin-independent. The specificity of binding combined with the efficiency of transport across the gut epithelium suggest that VP4 will provide a useful carrier for insecticidal peptides active within the hemocoel of key lepidopteran pests including S. frugiperda.