Rhinogobio nasutus, an endangered fish species endemic to the upper and middle reaches of the Yellow River in China, lacks essential genomic information on gonadal development, hindering research into its reproductive biology. To address this, mRNA-seq and miRNA-seq datasets derived from adult testis (n = 3) and ovary (n = 3) were integrated to characterize sex-biased expression profiles and potential regulatory mechanisms. A total of 34,813 genes and 68,623 transcripts were detected, and 16,105 differentially expressed genes (DEGs) were identified between testis and ovary, including 9365 testis-biased and 6740 ovary-biased genes. Small-RNA profiling identified 51 differentially expressed miRNAs (DEMs: 31 testis-biased; 20 ovary-biased). The sex-biased mRNA profiles highlighted conserved candidate genes associated with germ-cell maintenance, somatic regulation, ovarian differentiation, and oocyte maturation, including vasa, piwi, dmrt1, amh, cyp19a1a, zar1, zar1l, and rbpms2. Integrated miRNA–mRNA analysis further predicted potential interactions involving key sex-related genes, suggesting that DEMs may contribute to post-transcriptional regulation during gonadal differentiation. Functional enrichment (GO and KEGG analyses) highlighted pathways associated with gonadal differentiation, germline maintenance, and signal transduction pathways. qRT-PCR validation of nine mRNAs and nine miRNAs showed expression patterns consistent with the sequencing results. Collectively, these results provide an integrated mRNA and miRNA resource for R. nasutus gonads and identify candidate genes and miRNAs for future studies on sex-biased gonadal development, reproductive regulation, and artificial propagation.

The red swamp crayfish (Procambarus clarkii) is a globally important freshwater crustacean that exhibits pronounced sexual dimorphism, with males growing faster than females. However, the molecular mechanisms underlying sex differentiation in crustaceans remain poorly understood. In this study, Oxford Nanopore-based Direct RNA Sequencing (DRS) was employed to analyze the gonadal transcriptomes of male and female P. clarkii, identifying 20,001 previously unannotated genes and revealing extensive sex-specific differences in transcript structure, alternative splicing, and RNA modifications. Ovarian transcripts had shorter poly(A) tails and more frequent alternative splicing, while male gonads showed greater enrichment of m⁶A and psU modifications in the 3′ UTRs. qPCR validation confirmed the sex-biased expression of key candidate genes, including Dmrt7, FR, Fruitless, IAGBP, RDH, and Vtg. Collectively, these findings provide the first comprehensive epitranscriptomic landscape of P. clarkii gonads, underscoring the pivotal role of post-transcriptional regulation in sex determination and offering valuable insights for mono-sex breeding strategies in aquaculture.

The sustainable production of yellow catfish (Pelteobagrus fulvidraco) fry is critical for aquaculture, yet early developmental stages face high mortality and nutritional challenges. This study evaluated the effects of dietary supplementation with broken-cell wall P. rhodozyma on growth performance, organ development, enzyme activities, and gut microbiota composition in yellow catfish fry. Dietary supplementation with broken-cell wall P. rhodozyma significantly improved fry performance, increasing survival from 12% to 52%, promoting growth, enhancing intestinal and liver development, improving digestive enzyme activities, and modulating antioxidant-related physiological responses. It also elevated beneficial Muribaculum and reduced Streptococcus in the gut, promoting microbiota stability. These results demonstrate that P. rhodozyma supplementation not only improves early growth, organ maturation, stress resistance, and intestinal health but also effectively enhances overall fry health and development, thus supporting its use as a functional feed additive in aquaculture.

Rhinogobio nasutus, a freshwater fish belonging to the family Cyprinidae, is primarily distributed in the upper and middle reaches of the Yellow River. However, overfishing and habitat degradation have resulted in a marked decline in its wild populations, and the species was listed as a Class II nationally protected aquatic wildlife species in China in 2021. Spermatogonial stem cells (SSCs) provide a valuable resource for fish germplasm conservation and reproductive biotechnology. In this study, we successfully established a long-term cultured germ-cell population with spermatogonial stem cell-like characteristics derived from R. nasutus (RnSSCs). These cells exhibited a morphology consistent with an undifferentiated spermatogonial phenotype and showed a diploid chromosome number of 2n = 50. Alkaline phosphatase (AP) staining showed strong positive activity, while RT-PCR detected the expression of germ-cell- and stem-cell-associated markers, with only weak expression of the somatic-cell-associated marker. Immunofluorescence staining revealed strong signals for both proliferating cell nuclear antigen (PCNA) and the germ cell-specific protein Vasa. After more than four months of in vitro culture, the cells continued to proliferate and retained expression of germ-cell- and stem-cell-associated markers. Following transplantation into zebrafish blastulae, fluorescently labelled cells were detected in the gonadal region of a small number of recipient embryos. Following hormonal induction, some cells developed a sperm-like morphology, accompanied by the expression of the meiotic-associated markers rec8 and dmc1. The establishment of the RnSSC line provides a renewable cellular resource for studying spermatogenesis and germ cell transplantation in R. nasutus. These findings provide a useful cellular resource for studying the reproductive biology of R. nasutus.