Chengyan Mou

Introduction: Spring viremia of carp virus (SVCV) is a highly infectious pathogen threatening common carp ( Cyprinus carpio ). Hence, implementing protective measures is crucial to safeguard aquatic species and minimize economic impacts, including pharmaceuticals, vaccines, and breeding of resistant varieties. Common carp is a major aquaculture species, with breeding programs primarily focused on enhancing growth performance. However, evidence indicates that accelerated growth may compromise disease resistance, suggesting a trade-off between these traits. Methods: We challenged two carp populations with contrasting growth rates using SVCV and performed integrated multi-omics analyses. Results: Survival analysis showed that fast-growing carp had significantly lower survival than slow-growing carp, with growth negatively correlated with resistance (r = -0.83). RNA-seq analysis of head kidney tissues identified a Grey module gene via Weighted Gene Co-expression Network Analysis (WGCNA), positively linked to growth but negatively to resistance. KEGG enrichment analysis showed that genes within this module were significantly enriched in pathways related to xenobiotic metabolism, nutrient processing, and detoxification. Protein–protein interaction (PPI) network analysis highlighted three hub genes ( gsta4 , adh8b , and gimap7 ) potentially regulating both traits. Metabolomic profiling of liver tissues, combined with WGCNA, revealed three metabolite modules: Florawhite, positively associated with body weight and negatively with survival rate; Grey60, negatively associated with body weight and positively with survival rate; and Lightsheelblue, positively associated with survival rate only. These metabolites were predominantly enriched in pathways related to nutrient metabolism, digestion and absorption, and secondary metabolite biosynthesis. Correlation analysis between Grey module genes and metabolites identified 20 genes significantly associated with 159 metabolites. Among these, ss18 , arl5a , and hnrnph3 emerged as potentially pivotal. The metabolites highly correlated with these three genes were predominantly enriched in pathways related to nutrient metabolism, energy metabolism, detoxification and antioxidation, and immune regulation. Discussion: In summary, our integrated multi-omics analysis suggests that enhanced nutrient absorption and xenobiotic processing may contribute to superior growth performance in the YB population, while elevated detoxification and antioxidant capacity may underlie stronger disease resistance in the CD population. These findings provide insights into the interplay between growth and immunity in carp and offer biomarkers for balanced breeding strategies.

Body color is the most prominent phenotypic trait in animals. To investigate the molecular regulatory mechanisms underlying skin pigmentation and body color in Channa argus, single-nucleus RNA sequencing technology was employed to analyze cell diversity and functional changes in the skin of normal and albino C. argus. Three pigment-related cell types, seven immune-related cell types, and nine other skin-related structural and functional cell types were identified. The skin of albino C. argus, which appears white to the naked eye, contains numerous melanocytes and iridophores with reflective silver properties. Compared to normal C. argus, melanocytes in albino individuals contained fewer melanin granules, while iridophores exhibited increased chromogenic substances. Melanocyte-specific genes—kitlg, myo5a, and scarb1—were significantly downregulated in albino melanocytes (p < 0.05). Conversely, iridophore-specific genes alk, pnp, and gpnmb were significantly upregulated in albino skin, whereas mlph was significantly downregulated (p < 0.05). Weighted gene co-expression network analysis revealed that scarb1 was associated with the melanocyte module, alk was identified as a core gene, and pnp was linked to the iridophore module. Functionally, scarb1 is involved in pigment transport, pnp in purine synthesis, and alk is essential for iridophore development. Therefore, scarb1, pnp, and alk may be correlated to albinism in C. argus. Overall, this study constructed a single-cell transcriptional atlas of C. argus skin, providing valuable reference data for further research into the regulatory mechanisms governing body color formation and maintenance in this species.

The Yangtze sturgeon (Acipenser dabryanus) is designated as critically endangered in the IUCN Red List and is a first-class protected species in China. During the summer of 2024, it suffered lethal disease outbreaks. Comprehensive pathological and microbiological analyses were conducted to clarify the etiology. Clinically, infected sturgeon exhibited systemic manifestations including cutaneous ulcers, hemorrhagic septicemia, and diffuse necrosis in liver, kidney and heart tissues. Histopathologically, infected sturgeon showed liver hepatocyte vacuolation/necrosis, renal glomerular atrophy, and cardiac epicardial thickening with lymphocyte/eosinophil infiltration; Gram staining revealed co-localized Gram-positive/negative bacteria in lesions, and TEM identified diverse bacterial morphotypes. Through isolation and molecular identification, four bacterial pathogens were characterized: Streptococcus iniae, Klebsiella pneumoniae, Edwardsiella tarda, and Bacillus cereus. Bacterial load detection revealed the presence of these pathogens in lesion tissues. Antimicrobial susceptibility testing indicated multidrug resistance to florfenicol, tetracycline, and ampicillin (commonly used antibiotics in aquaculture), while high sensitivity to ceftazidime, ceftriaxone, and ciprofloxacin was observed. Thus, we infer that sustained high-temperature stress triggered bacterial co-infection is closely related to this large-scale death incident. This is the first evidence of polymicrobial infection in the Yangtze sturgeon, emphasizing the significance of shifting from a single-pathogen perspective to a multi-pathogen framework, and highlighting the urgency of implementing ecological prevention strategies for this species.

Microbial feed additives can effectively promote the healthy development of aquaculture, and Lactobacillus acidophilus can be utilized to mitigate disease risks and enhance productivity while minimizing antibiotic use. This article summarizes research on the application of L. acidophilus in aquaculture, focusing on growth and nutrient utilization, intestinal structure and microbial communities, disease prevention and control in aquatic organisms, and the regulation of water quality. This review holds significant implications for the development of compound feed additives and environmental regulators involving L. acidophilus, as well as for future aquatic food safety.

The transition from live bait (LF) feeding to compound feed (CF) feeding in aquaculture is of great production significance. In recent decades, cultivation with CF has become a focus for practitioners and researchers dealing with Siniperca chuatsi. This study focused on experimental subjects of S. chuatsi fed with CF and LF, using short-distance transportation as a stimulating factor. For the first time, the differences between S. chuatsi fed with CF and LF were analyzed from the perspective of stress response during transportation. This study found that after transportation stimulation, the activities of LZM and the contents of MDA, TGs, and glucose in the brain, liver, kidneys, muscles, stomach, pyloric caecum, intestines, and blood of S. chuatsi fed with CF were higher compared to S. chuatsi fed with LF (p < 0.05). Significant differences were observed in the impacts of various diets on the gastrointestinal tract, particularly in the intestine. In summary, this study found that S. chuatsi fed with CF could retain more energy after transport stimulation and exhibited stronger resistance to microbial stress, but they had a weaker antioxidant capacity. Therefore, in future research on CF for S. chuatsi, we need to focus on its ability to enhance antioxidant capacity.

Cold shock represents a prevalent but harmful environmental stress factor that poses significant threats to fish survival and reproductive success. In fish, the brain acts as a central regulator of thermoregulatory processes. Nevertheless, how different brain regions respond molecularly to cold exposure remains largely unknown. To address this, this study systematically investigated the effects of acute cold stress on five specific brain regions of Leiocassis longirostris using RNA-seq. The findings demonstrated that all five brain regions were significantly impacted by cold treatment, with the mesencephalon (MB) showing the most substantial changes. GO and KEGG enrichment analyses indicated that cold stress disrupted processes including gene expression regulation, circadian rhythms, and immune function within brain tissues. Through Weighted Gene Co-Expression Network Analysis (WGCNA), the MB was identified as the core responsive region, and the brain’s reaction to cold stress was strongly correlated with circadian rhythm, spliceosome, and ubiquitination. In summary, our investigation demonstrates that the MB represents a principal region for cold stress response in L. longirostris, involving alterations in circadian clocks, immune function, and inflammatory responses, alongside suppression of gene expression processes and ubiquitination-mediated proteolysis.

Understanding how distinct brain regions of Leiocassis longirostris molecularly adapt to heat stress is vital for improving aquaculture sustainability and guiding conservation strategies in a warming climate. To elucidate the region-specific molecular mechanisms underlying heat stress responses in the brain of L. longirostris, we exposed L. longirostris to acute heat stress (32°C) for 24 h and performed RNA-seq and WGCNA on five brain regions (OB: olfactory bulb, FB: pituitary, hypothalamus, forebrain, MB: mesencephalon, CB: cerebellum, and SC: spinal cord). The results showed that, after heat stress, the FB region significantly activated the ER stress pathway, and the abnormal proteins were synergically cleared by HSP-mediated UPR (such as Hsp70, Hsp90, IRE1α, Perk, ATF6) and UPS-mediated ERAD (such as UBE2, UBE3, TRIM63). Meanwhile, the SC region showed marked downregulation of lipid metabolism and PPAR signaling pathway, suggesting energy conservation as a compensatory strategy. WGCNA further highlighted the FB as the hub for ER stress and the SC for metabolic suppression. In conclusion, our study suggests that distinct brain regions of L. longirostris adopt different strategies under heat stress, in which the FB region mediates protein quality control and the SC region drives metabolic inhibition. These findings highlight the adaptation strategies of the L. longirostris brain to heat stress and provides a potential target for improving its survival under global warming.

Light influences the stress response to environmental stimuli and feeding behaviors of Siniperca chuatsi and, thus, is an important regulator of normal growth and development. In this study, we first explored the important role of light on the digestive and stress capacity of S. chuatsi by studying the changes in physiological and biochemical indicators of S. chuatsi, taking the re-feeding after starvation as the constant environmental stimulus and the light intensity as the adjustable environmental stimulus. The activity of protease and lipase was generally higher in the stomach tissues than in the intestinal tissues, especially lipase, which was higher in stomach tissues under all light conditions, and the protease and lipase activity peaked in the stomach tissues of S. chuatsi at a light intensity of 18.44 ± 3.00 lx and in intestinal tissues at 11.15 ± 2.01 lx, respectively, indicating that greater light intensity increased the digestive capacity of stomach tissues, whereas lower light intensity facilitated the digestive capacity of intestinal tissues. The tissues of the gill, stomach, and intestine had relatively high activity of stress-related enzymes, whereas the tissues of the brain, kidney, liver, and plasma samples had relatively low activity of enzymes. Collectively, the results show that light intensity at 11.15 ± 2.01 lx promoted digestive capacity in the intestine and enhanced the anti-stress ability of S. chuatsi in response to stress induced by re-feeding after starvation. These findings should prove useful for artificial breeding of S. chuatsi.

Freshwater aquaculture has a long and vibrant tradition in China. The Chinese longsnout catfish (Leiocassis longirostris) is a popular economic freshwater fish native to China. Understanding the genetic structure of L. longirostris populations is important for ensuring the efficacy of management practices and the sustainability of future increases in production. In this study, we used Illumina sequencing technology to isolate 20 novel polymorphic microsatellites from the genome of L. longirostris. These microsatellites were used to analyze the genetic diversity of 240 L. longrostris individuals from four populations. Genetic diversity parameters (N_A, H_O, H_E, I, PIC, and F_ST) of the four farmed L. longirostris populations were analyzed. The level of genetic differentiation among the four farmed L. longirostris populations (inferred by pairwise comparisons of F_ST values) was low, but the genetic diversity of these populations was high, indicating that they still provide useful sources of genetic variation that could aid in breeding efforts. The STRUCTURE and ADMIXTURE analyses indicated that admixture might be occurring in the four L. longirostris populations, especially between the MS and YB populations. Understanding the genetic diversity of farmed L. longirostris populations and inbreeding prevention could greatly aid in breeding and production. These newly isolated microsatellite markers and the high genetic diversity of L. longirostris populations in the main breeding areas have important implications for the breeding and stock management of L. longirostris.

Leiocassis longirostris is a commercially important fish species that shows a sexually dimorphic growth pattern. A lack of molecular data from the gonads of this species has hindered research and selective breeding efforts. In this study, we conducted a comprehensive analysis of the expression profile of miRNA and mRNA to explore their regulatory roles in the gonadal maturation stage of L. longirostris. We identified 60 differentially expressed miRNAs and 20,752 differentially expressed genes by sequencing. A total of 90 miRNAs and 21 target genes involved in gonad development and sex determination were identified. Overall, the results of this study enhance our understanding of the molecular mechanisms underlying sex determination and differentiation and provide valuable genomic information for the selective breeding of L. longirostris. Graphical Abstract