In this study, we determined the complete mitochondrial genome of Neolissochilus heterostomus. The genome is 16,585 bp in length, including 2 ribosomal RNA genes, 13 proteins-coding genes, 22 transfer RNA genes, and two non-coding control regions. Sequence analysis showed that the overall base composition of N. heterostomus is T 24.8%, C 27.7%, A 31.7%, and G 15.8%. The sequence is a slight A + T bias of 56.5%, which is similar to other fishes. We describe a phylogenetic analysis of 16 species of Cypriniformes based on the complete mitochondrial genome, and the result showed that N. stracheyi is most closely related to N. heterostomus. This mitogenome sequence data would play an important role in the investigation of phylogenetic relationship of the Cyprinidae.

Integrated multi-trophic aquaculture (IMTA) has emerged as an ecological intensification strategy capable of enhancing nutrient utilization and improving environmental stability in mariculture systems, yet the microbial mechanisms driving nutrient transformations remain insufficiently understood. This study investigated how culture mode (IMTA vs. monoculture) shape water quality, sediment microbial communities, and nutrient cycling processes in a shrimp–sea urchin system by combining water-quality monitoring, nutrient analysis, 16S rRNA high-throughput sequencing, and redundancy analysis. IMTA significantly increased turbidity, chlorophyll-a, phosphate, ammonium, and nitrite compared with monoculture, while physico-chemical parameters remained stable. Sediment microbiota in IMTA exhibited substantially higher alpha diversity and showed a clear compositional separation from monoculture communities. At the genus level, IMTA sediments were enriched in Vibrio, Motilimonas, and Ruegeria, distinguishing them from monoculture systems. At the phylum level, IMTA was characterized by increased abundances of Proteobacteria and Bacteroidota, accompanied by a marked decline in Spirochaetota. Functional predictions indicated that microbial communities were predominantly characterized by pathways related to amino acid and carbohydrate metabolism, as well as nutrient remineralization. RDA and correlation analyses further identified turbidity, chlorophyll-a, phosphate, ammonium, and nitrite as the principal drivers of microbial divergence. Overall, the findings demonstrate that IMTA reshapes sediment microbial communities toward more efficient nutrient-processing assemblages, thereby promoting active nitrogen and phosphorus transformations and improving biogeochemical functioning relative to monoculture. These results provide mechanistic insight into how IMTA supports nutrient recycling and environmental sustainability in modern mariculture systems.

Background/Objectives: The sarcoplasmic reticulum Ca²⁺-ATPase 1 (Atp2a1) is a key regulator of calcium homeostasis and muscle relaxation, yet its roles in fish remain poorly understood. Methods: We investigated the structural characteristics, phylogenetic relationships, and transcriptional regulation of atp2a1 in Acrossocheilus fasciatus, a stream-dwelling cyprinid sensitive to environmental fluctuations. Results: Bioinformatic analyses revealed that the 991-aa Atp2a1 protein is highly conserved among teleosts but exhibits divergence from mammals in the Cation_ATPase_N domain and transmembrane regions TM3, TM9, and TM10. Phylogenetic analysis clustered A. fasciatus most closely with Onychostoma macrolepis. Tissue-specific qRT-PCR demonstrated predominant expression in skeletal muscle, followed by testis, brain, heart, and gill. Promoter prediction identified binding motifs for KLF9, CTCF, MAZ, KLF5, ONECUT3, and HOXB13. qRT-PCR analysis showed that long-term cold acclimation (16 °C vs. 24 °C) markedly downregulated atp2a1 expression (ANOVA, p < 0.05, n = 3), whereas moderate flow velocity (2 BL·s⁻¹ vs. 0 BL·s⁻¹) significantly upregulated it (ANOVA, p < 0.05, n = 3). Alternative splicing analysis based on RNA-seq data further revealed a corresponding decrease and increase in skipped exon (SE) inclusion under cold and flow conditions, respectively (P_adj < 0.05). Conclusions: These results further raise the possibility that the regulatory complexity of atp2a1 contributes to adaptation of teleosts under fluctuating environments.

Cadmium (Cd) is a typical heavy metal pollutant in aquatic environments. It enters fish through the gills, digestive tract, and body surface, and accumulates mainly in the liver and kidneys, with species- and tissue-specific distribution. Cadmium triggers apoptosis by inducing oxidative stress, calcium imbalance, and DNA damage. These signals are integrated and amplified by the mitogen-activated protein kinase (MAPK), nuclear factor kappa B (NF-κB), phosphatidylinositol 3-kinase (PI3K)/AKT, and nuclear factor erythroid 2-related factor 2 (Nrf2) pathways, ultimately activating three downstream apoptotic execution pathways: the death receptor, mitochondrial, and endoplasmic reticulum stress pathways. These three pathways form an interactive network through molecular nodes such as BH3 interacting domain death agonist (Bid), Ca²⁺, c-Jun N-terminal kinase (JNK), and C/EBP homologous protein (CHOP), synergistically amplifying the apoptotic effect, with the mitochondrial pathway playing a central role. Cadmium-induced apoptosis is dose-dependent: low concentrations activate protective responses, whereas high concentrations strongly promote apoptosis. Current research gaps remain regarding dynamic pathway crosstalk, chronic low-dose effects, species differences, and fish-specific apoptotic molecules (e.g., caspase-12 homologs). Future studies should focus on constructing multidimensional response maps, clarifying pathway activation thresholds and interaction contributions, and developing composite protective strategies based on Nrf2 activators, metal chelators, and antioxidants, thereby promoting translation into ecological risk assessment and aquaculture pollution control.