The moulting arthropod: a complete genetic toolkit review

Stage-specific transcriptomic analysis reveals insights into the development, reproduction and biological function of allergens in the European house dust mite Dermatophagoides pteronyssinus

BACKGROUND

House dust mites (HDMs) such as Dermatophagoides pteronyssinus are major allergy elicitors worldwide, yet their gene expression across developmental stages remains underexplored. Herein, we report a comprehensive RNAseq analysis of larvae, nymphs, and adult males and females, mapped to a recently published high-quality genome with extended functional annotations.

RESULTS

Analysis of differentially expressed genes (DEG) revealed that female-biased expression was the most prevalent profile (16% of genes), while males exhibited the highest fold-change differences. DEG data, combined with network clustering and functional enrichment analysis, highlighted distinct genes and biological processes for each stage and sex: females showed upregulation of genes related to cell division and oogenesis, with vitellogenins among the most abundant transcripts; males exhibited increased expression of genes encoding putative seminal fluid proteins (e.g. endopeptidases, serpins, antimicrobial peptides), and those involved in reproductive regulation (e.g. testis-specific serine kinases); while juveniles displayed enhanced expression of genes related to energy metabolism and growth. Further analysis of endocrine pathways revealed non-canonic mechanisms compared to insect models, particularly in ecdysteroid and sesquiterpenoid biosynthesis and regulation. Expression patterns in genes involved in cuticle formation were also identified, reflecting their role in developmental transitions and sexual differentiation. Allergen and allergen-related gene expression showed an overall increase in feeding juveniles, as well as sex-biased expression, with Der p 27 upregulated in females. These findings provide insight into the physiological roles of allergens in digestion, immunity, and muscle formation, among other functions. Additionally, seven new horizontally transferred genes, including a DNA-repair photolyase linked to females, and novel multigene families (e.g. 119 male-specific beta-propeller proteins, 70 hypothetical cuticular proteins, 23 tetraspanin-like proteins, 5 female-associated putative odorant-binding proteins) were identified.

CONCLUSIONS

This study provides the first genome-wide transcriptomic analysis of a HDM across life stages and sexes, expanding our understanding of the molecular mechanisms underlying mite development, sexual reproduction, and allergen expression. The generated data, fully available via supplementary spreadsheet and the ORCAE online platform, provide a valuable foundation for future allergy research and the development of new mite control strategies.

Chitin Synthase Is Required for Cuticle Formation and Molting in the Chinese Mitten Crab Eriocheir sinensis

Chitin synthase is an essential enzyme of the chitin synthesis pathway during molting. In this study, we identified and characterized a chitin synthase (EsCHS) gene in the Chinese mitten crab, Eriocheir sinensis. The spatio-temporal expression and functional role of EsCHS were investigated. The open reading frame of EsCHS was 4725 bp long and encoded 1574 amino acid residues that contained the typical domain structure of the glycosyltransferase family 2. Phylogenetic analysis revealed that EsCHS belongs to the group I chitin synthase family. The expression of EsCHS was found in regenerative limbs, the cuticle and the intestines. During the molting cycle, EsCHS began to increase in the pre-molt stage and reached a significant peak in the post-molt stage. The knockdown of EsCHS resulted in the significant downregulation of chitin biosynthesis pathway genes, including TRE, HK, G6PI, PAGM and UAP. Moreover, the long-term RNAi of EsCHS resulted in thinning procuticles, abnormal molting and high mortality, suggesting that EsCHS is indispensable for the formation of chitin in the cuticle during molting. In conclusion, EsCHS is involved in the chitin biosynthesis pathway and plays an important role in molting in E. sinensis. These findings highlight the potential of incorporating EsCHS into selective breeding programs to optimize molting regulation and improve growth performance in crustacean aquaculture.

Key Neuropeptides Regulating Molting in Pacific White Shrimp (Penaeus vannamei): Insights from Transcriptomic Analysis

Molting is a vital physiological process essential for the growth and development of Penaeus vannamei, with significant implications for aquaculture productivity. This study aimed to identify neuropeptide-related genes involved in molting through transcriptomic analysis. RNA sequencing of pre-molt and post-molt samples revealed 1203 differentially expressed genes (DEGs). Functional enrichment analysis indicated that these genes play significant roles in cuticle formation and molting regulation. Among the DEGs, 243 were predicted to be neuropeptides based on the presence of signal peptides and the absence of transmembrane domains. Five key neuropeptide genes-PvCHH, PvMIH, PvEH I, PvCDA I, and PvCDA II-were identified as critical regulators of molting. Their role was further validated through RT-qPCR analysis, confirming their close association with the molting process. These genes were highlighted in this study as pivotal factors driving molting in P. vannamei. The neuropeptides identified in this research are anticipated to offer valuable insights into the regulation of molting. Additionally, their synthetic products hold promise for improving molting consistency in shrimp aquaculture.

ame-miR-5119-Eth axis modulates larval-pupal transition of western honeybee worker

The miRNA plays a key role in the regulation of hormone signaling in insects. The pathways by which miRNAs affect hormone levels are unclear in the honeybee (Apis mellifera), an indispensable pollinator in nature. In this study, ame-miR-5119 was overexpressed and knocked down in larvae by feeding mimics and inhibitors, respectively, and we determined that ame-miR-5119 regulates hormone signaling through the target gene ecdysis triggering hormone (Eth), which affects the larval-pupal transition of workers. The results showed that ame-miR-5119 with a length of 19 nt targets six genes related to the hormone pathway. We focused on Eth and found that ame-miR-5119 and Eth exhibited reverse expression patterns during the transition from larval to pupal stages in workers. Dual luciferase assay confirmed the negative regulatory between ame-miR-5119 and Eth. Overexpression of ame-miR-5119 decreased the mRNA level of Eth, and the Eth receptor (Ethr) expression was not significantly affected, but the expression levels of juvenile hormone (JH) pathway related genes juvenile hormone acid methyltransferase (Jhamt) and Krüppel homolog 1 (Kr-h1) were significantly reduced. In contrast, knockdown of ame-miR-5119 increased the mRNA level of Eth, and the expression of Ethr, Jhamt and Kr-h1 was significantly upregulated. ame-miR-5119 did not affect larval body weight. The number of larvae overexpressing ame-miR-5119 survived in the prepupal stage was lower than that in the control group, and the number of pupations reduced at 11-day-old. The number of larvae that knocked down ame-miR-5119 survived in the prepupal stage was significantly higher than that in the control group, and the number of pupations increased at 11-day-old. These results indicated that ame-miR-5119 negatively regulates the expression of Eth, indirectly inhibits the expression of Ethr, Jhamt, and Kr-h1, and affects the JH biosynthesis, thereby preventing the metamorphic transition from larva to pupa in worker bees. These findings provide evidence that the miRNA regulation of hormone levels in honey bees.