Guanwang Shen

Estrogen-related receptors (ERRs) have no natural ligands, vertebrate ERRs rely on their activation function-2 (AF-2) structural domain to recruit coactivators for transcriptional regulation. While metabolic regulation in insects differs significantly from that in vertebrates, it remains unclear whether the regulatory function of insect ERR requires coactivators. Using silkworms as the research subject, this study aims to analyze the molecular mechanisms of ERR-regulated metabolism in insects and refine the metabolic regulatory network. This study applied CRISPR/Cas9 gene editing technology to knock out the AF-2 domain of BmERR in the lepidopteran silkworms and examined its effects on functional role, associated interacting factors, and related physiological processes. Disruption of the BmERR AF-2 domain inhibited the expression of melanin metabolism-related genes BmTH , BmDDC , BmAA-NAT , Bmebony , and Bmtan , leading to the accumulation of tyrosine and dopa, thereby causing aberrant melanin metabolism and loss of epidermal markings. By contrast, BmERR overexpression enhanced the pathway, resulting in intensification of epidermal markings. The homologous gene of the ERR coactivator, BmPPRC1, showed highly consistent expression with BmERR in the epidermis. The immunofluorescence signal of BmPPRC1 was localized to the nucleus and highly overlapped with that of BmERR. BmPPRC1 interacts with the AF-2 domain of BmERR, and deletion of this region weakens the regulation of melanin metabolism-related genes in silkworm embryonic cells. The ERR function and mode of action are evolutionarily conserved, and its AF-2 structural domain binds equally well to the coactivator BmPPRC1, providing new perspectives for studying the modulability of insect mottle formation.

Total sugar is one of the chemical indicators related to tobacco quality. However, due to its composition of various oligosaccharides, disaccharides, and polysaccharides, total sugar lacks a clear genetic target, making conventional breeding approaches for its improvement particularly challenging. Therefore, conducting genomic selection (GS) studies on total sugar content holds significant importance for the development of high-sugar tobacco varieties. In this study, 2,604 tobacco germplasm accessions with broad genetic diversity, sourced from the National tobacco Germplasm Repository, were used as experimental materials. High-throughput sequencing technologies were employed to perform comprehensive genetic evaluation and construct genomic selection models for total sugar content. Sixteen mainstream genomic prediction models were assessed through five-fold cross-validation to develop a high-accuracy prediction framework. Among these models, the Gradient Boosting Machine (GBM) achieved the highest prediction accuracy for total sugar content (0.85), followed by the rrBLUP model (0.81). Comparative analysis of computational speed and resource consumption revealed that GBM maintained rapid computation and low resource usage even in large sample sizes, demonstrating strong stability and superior performance. Considering all factors, GBM was preliminarily identified as the optimal model for predicting total sugar content in tobacco. The application of high-accuracy genomic prediction is expected to overcome the challenges of phenotypic evaluation in breeding programs and significantly enhance the efficiency of selecting high-sugar tobacco varieties.

This study aimed to investigate how mulberry leaf powders from different mulberry varieties influenced the quality of artificial diet for domestic silkworms. Using metabolomics, we examined the possible reasons why silkworm rearing performance varied, and provided new research ideas for improving diet quality. Forage mulberry leaves differed from grafted mulberry leaves in metabolic pathways related to fatty acids, amino acids, and vitamin C. Forage mulberry leaf powder showed considerably decreased amounts of vitamin C, serine, linoleic acid, and linolenic acid, all of which are required for the production of silk proteins and their intermediates. A considerable increase in 1-deoxynojirimycin (DNJ) content was observed. The feeding characteristics of silkworms led to decreased DNJ tolerance and lower quality of silkworm diet made from forage mulberry leaf powder compared to that made from grafted mulberry leaf powder. Furthermore, the body weight during the silk-spinning stage, cocoon weight, and Cocoon shell ratio of the reared silkworms were all markedly reduced. Using mulberry leaf powder would require addressing the problem of reduced DNJ tolerance in silkworms owing to the changes in their diet, in addition to improving the composition of the silkworm diet based on the characteristics of the mulberry leaf powder.

DHX8 encodes a DEAH-box RNA helicase, an ATP-dependent enzyme that plays essential roles in RNA metabolism, including pre-mRNA splicing, transcription, and mRNA decay. Although DHX8 dysfunction has been linked with developmental abnormalities and disease pathogenesis in multiple model organisms, its biological functions in Lepidoptera, particularly in the silkworm Bombyx mori, remain unknown. To investigate the developmental role of B. mori DHX8 (BmDHX8), we generated knockout mutants using CRISPR-Cas9 genome editing. Genome sequencing confirmed frameshift mutations in the BmDHX8 locus. BmDHX8 mutants exhibited severe developmental defects such as dramatically reduced body size and premature lethality of silkworm larvae. Molecular characterization suggested systemic dysregulation, as evidenced by decreased triglyceride accumulation, impaired mTOR signaling activity, and increased aberrant splicing events. Therefore, these results indicate that loss of BmDHX8 is associated with aberrant splicing and alterations in lipid homeostasis and mTOR signaling pathways, potentially contributing to developmental defects. Taken together, our study offers an initial functional knockout analysis of BmDHX8 in regulating larval development in silkworms.

Background: Beauveria bassiana infection of silkworm forms Bombyx Batryticatus (BB). It is a medicinal material with significant pharmacological potential. While artificial diet feeding improves the production efficiency of BB, it might alter host metabolism, consequently affecting its bioactive components and efficacy. To address this, we conducted a metabolomics analysis of BB reared under different feeding conditions; Methods: UPLC-MS/MS was employed to conduct metabolomic analysis of BB under three rearing conditions: all instars mulberry leaf feeding (MF), all instars artificial diet feeding (AF), and mixed feeding (AMF). The sample collection time was selected as the time when silkworms died after infection (D0), and the fifth day after death (D5), which is the time when fungus produces biologically active secondary metabolites to reach a stable state; Results: Compared to MF, AF did not significantly alter the levels of the index component induced by B. bassiana infection—beauvericin. Moreover, the overall metabolic profile differences between the two groups decreased at the later stage (D5). Specifically, the average Pearson correlation between these groups was 0.659 ± 0.102, and the first two principal components of PCA explained 49.6% of the total variance. This suggests a reduction in the differences in their pharmacological active components. KEGG enrichment analysis revealed that AF promoted the accumulation of certain flavonoids (e.g., apigenin, luteolin), but, overall, the biosynthesis of flavone and flavonol is suppressed. Additionally, several metabolites, including N,N′-diferuloylputrescine, N-methyl-4-aminobutyric acid, and 3,4-dimethoxyphenylacetic acid, were identified to be significantly positively correlated with artificial diet supplementation; Conclusions: This study reveals metabolic differences in BB under different rearing methods at the metabolomic level, providing a scientific basis for evaluating the quality of this medicinal material.

BACKGROUND: Pest resistance to chemical and biological control methods remains a persistent challenge. Thus, target genes and resistance‐related mechanisms must be identified to improve control efficiency. Although a large number of studies have been dedicated to enhancing the biological control efficacy of insect pathogenic fungi (such as Beauveria bassiana ), the robust pest immune responses still limit its applicability. We therefore aimed to investigate the role of signal peptide peptidase (SPP) in the resistance of silkworm to B. bassiana . To this end, we examined its impact on chitin synthesis and explored potential metabolic interventions to enhance biological control efficacy against pests. RESULTS: SPP‐knockout silkworm ( BmSPP ^KO ) infected with B. bassiana were susceptible to this fungus. This increased susceptibility was attributed to disruption of the chitin synthesis pathway in the cuticle. BmSPP ^KO silkworms exhibited reduced expression of genes associated with chitin synthesis, along with decreased hexokinase and glucose 6‐phosphate contents in the epidermis compared to those in B. bassiana ‐infected wild‐type silkworms. This disruption inhibited chitin synthesis in the epidermis, leading to reduced thickness of the chitin layer. However, monosaccharide supplementation reversed this susceptibility phenotype. CONCLUSION: This study indicates that the host's SPP is a promising target gene for pest control because disruption of its function can enhance the virulence of B. bassiana . This discovery provides a basis for the broad‐spectrum enhancement synergistic of B. bassiana . © 2025 Society of Chemical Industry.

Diapause is a quintessential survival strategy orchestrated through animal–environment coevolution. Although extensive studies have been conducted using the silkworm, Bombyx mori , as the predominant diapause model, the molecular mechanisms underlying this process remain largely elusive. In this study, through transcriptomic profiling of serosal tissues comparing diapause‐destined (DD) and nondiapause‐destined silkworm eggs, we identified 2 790 upregulated and 2 791 downregulated genes in DD serosa. Functional enrichment analysis revealed significant associations of differentially expressed genes with key metabolic pathways, including amino sugar and nucleotide sugar metabolism, cell cycle regulation, and fatty acid elongation. Temporal expression profiling demonstrated stage‐specific expression patterns of these differentially expressed genes across different diapause phases. CRISPR/Cas9‐mediated knockout of the DD serosa‐specific trehalose transporter gene ( Tret1 ) reduced the trehalose consumption, concomitant with reduced sorbitol accumulation, and thus decreased the diapause incidence. Our findings provide novel insights into the serosa‐mediated regulatory mechanisms governing embryonic diapause in B. mori .