Against the backdrop of hydropower development in the upper Yellow River, comprehending the spatiotemporal variation and ecological evaluation of macroinvertebrate functional feeding groups (FFGs) is paramount for the conservation and restoration of aquatic biological resources in watersheds. Detailed surveys of macroinvertebrates were conducted in the gorge and plain areas of the upper Yellow River in July 2022 and March, May, and October 2023, culminating in the identification of 65 taxonomic units (genus or species) spanning 4 phyla, 14 orders, and 35 families. Of these, 41 taxonomic units were discovered in the gorge areas and 57 in the plain areas. Among the FFGs of macroinvertebrates in the upper Yellow River, collector-gatherers were overwhelmingly dominant, followed by scrapers, collector-filterers, predators, and shredders. Concerning river section types, dominant species in the gorge areas included Gammarus sp., Limnodrilus hoffmeisteri, and Polypedilum sp. among collector-gatherers, while in the plain areas, dominant species included Ecdyonurus sp. among scrapers, Hydropsyche sp. among collector-filterers, and Gammarus sp., Limnodrilus hoffmeisteri, and Chironomus sp. among collector-gatherers. A Mantel test revealed that dissolved oxygen, conductivity, and orthophosphate were the primary environmental factors affecting the FFGs of macroinvertebrates in the upper Yellow River, with variations observed in their effects across different months. The evaluation results of the Hilsenhoff Biological Index and Shannon–Wiener Index indicate that the water quality of the upper Yellow River is at a moderate level. An assessment of the upper Yellow River ecosystem using FFG parameters demonstrated that macroinvertebrate biomass progressively increased from upstream (gorge areas) to downstream (plain areas) spatially, accompanied by increasing habitat stability, with cascade hydropower development identified as a key factor impacting habitat stability. These findings provide pertinent data and a theoretical foundation for the protection of aquatic biological resources and watershed management in the upper Yellow River.

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.

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.