Angulyagra polyzonata is an economically important mollusk in China, but detailed insights into its mitochondrial genome remain scarce. In this study, we sequenced and comprehensively analyzed the structural features and selection pressures of the A. polyzonata mitochondrial genome. The maximum likelihood method and Bayesian phylogenetic inference method were used to construct a phylogenetic tree of A. polyzonata with 21 other species, including gastropods and bivalves. The full-length mitochondrial genome of 17,379 bp was found to include 22 transfer RNA genes, 2 ribosomal RNA genes, and 13 protein-coding genes, exhibiting similarity to the composition and arrangement of mitochondrial genes in other gastropod species. Notably, the Ka/Ks ratios of mitochondrial protein-coding genes (nad5, cox3, nad3, nad2, cox1, cox2, atp8, atp6, nadl, nad6, cob, nad4l, and nad4) were <1, which indicates that the snail genes of the three genera of the family may have been subjected to strong natural selection pressure during the evolutionary process, so that the number of synonymous mutations (ks) in genes was much more than that of nonsynonymous mutations (ka). Comparative genomic analysis indicated that, apart from the absence of trnW and trnQ, the gene composition of A. polyzonata shares a high degree of homology with other members of the conical snail family. Phylogenetic analysis demonstrated that the selected species could be classified into two primary clades in which A. polyzonata clustered with the Viviparidae family. This study bridges the knowledge gap regarding the mitochondrial genome of A. polyzonata and offers valuable insights into the systematic relationships within the Viviparidae family.

Bellamya limnophila is a mollusk of significant medical and economic value in China. Understanding the complete mitochondrial genome of this species will better establish a foundation for systematic classification research on Viviparidae. Therefore, we sequenced the complete mitochondrial genome of B. limnophila, conducted a comprehensive analysis of its structural characteristics, and constructed a phylogenetic tree using maximum likelihood and Bayesian methods. The results showed that the genome sequence is 16,991 bp in length, including 13 protein-coding genes (PCGs), 20 transfer RNA genes (tRNAs), 2 ribosomal RNA genes (rRNAs), and 1 non-coding region (D-loop). In summary, the Ka/Ks ratios of all PCGs were <1, indicating that purifying selection dominated the evolutionary process of these snails. The entire genome structure exhibited conservative features, such as the majority of start codons being the standard ATG codon and the majority of tRNA genes having the standard cloverleaf secondary structure. B. limnophila and B. quadrata showed collinearity in terms of sequence homology. Phylogenetic analysis indicates that the clade formed by the genera Margarya, Cipangopaludina, and Bellamya is the sister group of the genus Viviparus; Bellamya limnophila is more closely related to B. quadrata than to other species. This study contributes to the mitochondrial genome database of the family Viviparidae and provides valuable insights into the phylogenetic relationships of related snails.

Non-alcoholic fatty liver disease (NAFLD) is a primary metabolic disorder that threatens adolescent health globally, with no effective therapeutic agents currently available. Bellamya purificata is a traditional Chinese medicine categorized as "medicinal food", and polysaccharides are among its active components. However, its physicochemical structure remains poorly characterized, and no study has evaluated its effects on NAFLD. In this study, a homogeneous neutral polysaccharide, α-D-glucan (Mw = 6412.704 kDa), was isolated from B. purificata. The structure of the polysaccharide was characterized using monosaccharide composition analysis, methylation analysis, NMR spectroscopy, and scanning electron microscopy. The backbone structure of the polysaccharide comprises →4)-α-D-Glcp-(1→ and →4,6)-α-D-Glcp-(1→, with side chains of α-D-Glcp-(1→ attached to the O-6 position of the 1→4,6)-α-D-Glcp-(1→ sugar residues. Additionally, QSPS-1D effectively reduced weight gain, hepatic lipid accumulation (TC and TG), and inflammatory responses (tnf-α and il-1β) in NAFLD zebrafish. Moreover, QSPS-1D alleviated dysbiosis by inhibiting harmful bacteria (e.g., Stenotrophomonas, Agrobacterium, and Chryseobacterium) and promoting beneficial microbiota (e.g., Rothia), which restored the Firmicutes-to-Bacteroidetes ratio. In parallel, it enhanced the expression of tight junction proteins (zo-1 and claudin-1), leading to the repair of the intestinal mucosal barrier. These findings suggest that B. purificata polysaccharides may be a potential functional food for early NAFLD intervention, with effects potentially associated with the modulation of the gut microbiota.

Anti-Müllerian hormone (Amh) is a key regulator of sex determination and differentiation in fish. In this study, we identified and characterized a single-copy Amh ortholog, designated CmAmh, in blotched snakehead (Channa maculata), an economically important species in China. The cDNA spans 2340 bp and encodes a 545-amino-acid protein with conserved AMH-N and TGF-β domains. CmAmh exhibited pronounced male-biased gonadal expression, with transcript levels in testes markedly exceeding those in ovaries across all developmental stages (45~365 days post-hatching (dph)). Cellular localization revealed CmAmh transcripts in the Sertoli cells and spermatogonia of the testis and, more weakly, in the oogonia and primary oocytes of the ovary, suggesting a primary role in spermatogenesis and a potential modulatory function in early oogenesis. A strong inverse correlation between promoter CpG methylation and transcriptional activity, hypermethylation in ovaries (82.5~89.7%) versus hypomethylation (15.8~19.1%) in testes, indicated epigenetic regulation, which functionally integrates with hormonal signaling: 17β-estradiol (E₂) suppressed, whereas methyltestosterone (MT) upregulated CmAmh expression. Long-term E₂ exposure induced male-to-female secondary sex reversal (SSR) in 26.7% of XY individuals, whereas MT failed to reverse XX fish, indicating that CmAmh modulation alone is insufficient to override ovarian fate. Furthermore, CRISPR/Cas9-mediated mutagenesis achieved 40~45% editing efficiency, predominantly generating frameshift alleles, providing a platform for future functional studies. Collectively, these findings position CmAmh as a hormone-responsive nodal point within a broader sex-differentiation network. This work provides a theoretical foundation for sex-control strategies in C. maculata aquaculture, while future studies should focus on homozygous mutant generation to definitively establish its loss-of-function phenotype and regulatory networks.

The anti-Müllerian hormone type II receptor (Amhr2) is a critical component of the transforming growth factor-β (TGF-β) signaling pathway and plays essential roles in sex determination and gonadal development in teleosts. However, its function in the blotched snakehead (Channa maculata), an economically important fish in China, remains unexplored. In this study, we cloned and characterized the Amhr2 ortholog from C. maculata, designated CmAmhr2. The gene encodes a 443-amino acid protein containing a conserved STYKc kinase domain. Sequence and phylogenetic analyses revealed that CmAmhr2 is homologous to autosomal Amhr2 in other teleosts. Spatiotemporal expression analyses showed that CmAmhr2 was predominantly expressed in testes, particularly during critical windows of gonadal differentiation. In situ hybridization localized CmAmhr2 transcripts mainly in spermatogonia, with weaker signals in primary spermatocytes, Sertoli cells, and early-stage oocytes (oogonia and primary oocytes). Dietary administration of 30 mg/kg 17β-estradiol (E₂) from 15 to 45 days post-fertilization (dpf) for 30 days induced male-to-female sex reversal, producing neofemales (XY-F) and intersex individuals (XY-I). CmAmhr2 expression levels progressively declined with the degree of gonadal feminization: highest in normal XY male (XY-M) testes, intermediate in XY-I ovotestes, and lowest in fully feminized XY-F and normal XX female (XX-F) ovaries. Furthermore, CRISPR/Cas9-mediated mutagenesis of CmAmhr2 generated frameshift mutations predicted to disrupt the kinase domain. These findings suggest that CmAmhr2 is involved in male sex differentiation and testis development in C. maculata, providing novel molecular insights and a foundation for future sex-control research in aquaculture.