Metabolic changes during larval-pupal metamorphosis of Helicoverpa armigera

Estrogen-Related Receptor Potential Target Genes in Silkworm (Bombyx mori): Insights into Metabolic Regulation

Estrogen-related receptors (ERRs) are important transcription factors within the nuclear receptor family that regulate cellular energy storage and consumption by binding to estrogen-related receptor response elements (ERREs) on gene promoters. While ERRs' role in vertebrates is well-studied, their molecular mechanisms in insect metabolism and development remain unclear. This study systematically summarizes the functions of ERRs in insects, focusing on silkworms by analyzing gene functions and comparing databases. ERRE-like elements were identified in the 2000 bp upstream promoter regions of 69 metabolism-related silkworm genes. Furthermore, electrophoretic mobility shift assays (EMSAs) revealed that ERREs within the promoters of 15 genes related to sugar, fat, and protein metabolism specifically bind to ERR. Notably, an ERRE in the promoter of the trehalose transporter 1 gene (BmTret1), crucial for trehalose homeostasis in insect hemolymph, exhibited significantly enhanced activity in ERR-overexpressing cells. These findings suggest that ERR is a potential regulatory factor in silkworm metabolism and refine its metabolic regulatory network. This study highlights the broader and more critical role of ERR in insects than that previously recognized, contributing to a deeper understanding of insect metabolism and its potential applications in related fields.

Unravelling the Role of Insulin-Like Peptide Genes in Bombyx mori: Potential Key Regulators of Insect Metabolism

Understanding gene expression in specific tissues and their modulation under environmental stimuli, such as nutritional deficiency, reveals the key physiological regulatory mechanisms of an organism. This study examined the tissue-specific expression of insulin-like peptide (ILP) genes (BmX and BmZ) in Bombyx mori larvae and their responses to hyperglycaemia, food deprivation and hormonal (20-hydroxyecdysone and bovine insulin) treatments. mRNA expression levels of BmX and BmZ were analyzed in the brain, fat body, midgut and ovary. The results revealed that BmX was highly expressed in the fat body, while both genes were abundant in the ovary. Hyperglycaemia increased BmX mRNA expression level in the midgut (3.07-fold) and brain (7.53-fold), while BmZ mRNA expression level was increased in all tissues except the midgut. Nutrient deficiency upregulated BmX mRNA expression level (1.36-fold) in the fat body while reducing it (-0.53-fold) in the midgut. Food deprivation progressively increased (0.77-fold at 24 h and 2.34-fold at 72 h) BmX mRNA expression level in the fat body, while both BmX and BmZ transcripts declined in the midgut. Insulin suppressed BmX (-0.25-fold) and BmZ (-0.91-fold) mRNA expression levels in food-deprived larvae in the fat body, whereas 20E consistently downregulated BmX, BmZ, and BmInR (insulin receptor) mRNA expression levels in all the conditions. These findings revealed the complex interaction of gene expression, tissue specificity, and environmental factors in B. mori larvae and provided insights into adaptive responses to nutritional stress and hormonal regulation in the insect with potential applications in sericulture and agricultural biotechnology.

The role of gut microbiota at different developmental stages in the adaptation of the Etiella zinckenella to a plant host

Insect gut symbiotic microbiota play a crucial role in the nutritional, physiological, and behavioral aspects of their hosts, providing valuable insights for investigating the co-evolution of insects and plants. Sophora alopecuroides L. serves as an important windbreak plant, while Etiella zinckenella is a major pest that infests its seeds. However, the structure of the gut microbiota community in E. zinckenella remains poorly understood. In this study, we analyzed the gut microbiota of E. zinckenella across different developmental stages-larvae (1st-5th instars), pupae, and adults-infesting S. alopecuroides using 16 S rRNA high-throughput sequencing. The results revealed that the dominant phyla throughout the development of E. zinckenella were Proteobacteria and Bacteroidota, although the dominant genera varied significantly across stages. Diversity analysis of gut microbiota at different developmental stages indicated that microbial diversity was significantly higher in the larval stage compared to the pupal and adult stages. Functional predictions further highlighted the richness of metabolic pathways within the gut microbiota of E. zinckenella. Notably, carbohydrate metabolism functions were significantly more abundant during the larval stage, while lipid metabolism functions were substantially lower. Our findings demonstrate dynamic changes in the composition and diversity of the gut microbiota across the developmental stages of E. zinckenella, underscoring the critical roles of these bacteria during specific stages of the insect's life cycle. This study lays the groundwork for future strategies aimed at controlling E. zinckenella through modulation of its gut microbiota, offering significant theoretical implications.

Comparative analyses of the transcriptome among three development stages of Zeugodacus tau larvae (Diptera: Tephritidae)

Studying differences in transcriptomes across various development stages of insects is necessary to uncover the physiological and molecular mechanism underlying development and metamorphosis. We here present the first transcriptome data generated under Illumina Hiseq platform concerning Zeugodacus tau (Walker) larvae from Nanchang, China. In total, 11,702 genes were identified from 9 transcriptome libraries of three development stages of Z. tau larvae. 7219 differentially expressed genes (DEGs) were screened out from the comparisons between each two development stages of Z. tau larvae, and their roles in development and metabolism were analyzed. Comparative analyses of transcriptome data showed that there are 5333 DEGs between 1-day and 7-day old larvae, consisting of 1609 up-regulated and 3724 down-regulated genes. Expressions of DEGs were more abundant in L7 than in L1 and L3, which might be associated with metamorphosis. Gene Ontology (GO) enrichment and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis suggested the enrichment of metabolic process. KOG annotation further confirmed that 20-hydroxyecdysone (20E) pathway related genes Cyp4ac1_1, Cyp4aa1, Cyp313a4_3 were critical for the biosynthesis, transport, and catabolism of secondary metabolites and lipid transport and metabolism. Expression patterns of 8 DEGs were verified using quantitative real-time PCR (RT-qPCR). This study elucidated the DEGs and their roles underlying three development stages of Z. tau larvae, which provided valuable information for further functional genomic research.