To evaluate the potential of compound attractants in ameliorating diet-induced intestinal dysfunction in Siniperca chuatsi fed commercial compound feed, this study investigated their effects on intestinal metabolism and microbiota composition. In this study, four distinct diets are formulated: a control diet without attractants and three experimental diets supplemented with compound attractants A (nucleotides and L-glutamic acid), B (nucleotides, L-glutamic acid, and allicin), and C (nucleotides, L-glutamic acid, and betaine). Over a period of 8 weeks, groups of S. chuatsi were fed these diets, after which we assessed the intestinal microbiota and transcriptomic responses. KEGG pathway analysis of differentially expressed genes (DEGs) indicated that the A group exhibited significant changes predominantly in intestinal cholesterol homeostasis and inflammatory responses. The B group showed DEGs primarily associated with mucosal immune functions and pro-inflammatory cytokine signaling. Diversely, the C group revealed DEGs chiefly tied to immune and inflammatory response pathways. Furthermore, the intestinal microbiota exhibited beneficial modifications at both the phylum and genus levels in the A and B groups, while such beneficial shifts were not observed in the C group. These findings indicated that dietary supplementation with compound attractants A and B could positively influence both the intestinal transcriptomic landscape and microbiota composition in S. chuatsi, highlighting their potential as effective additives in compound feeds for aquaculture.

The lack of scientifically-based light environment management has constrained the sustainable development of intensive mandarin fish (Siniperca chuatsi). This study systematically evaluated the behavioral preferences and physiological adaptations of mandarin fish to red light (RL), yellow light (YL), green light (GL), blue light (BL), white light (WL) and dark area (DA). Individual behavioral results indicated that S. chuatsi exhibited the strongest phototaxis toward RL, with a preference order of RL > DA > YL > BL > GL > WL. Group distribution dynamics showed that the proportion of fish in the RL remained the highest throughout the 48-h observation period. Fish in the DA exhibited significant aggregation dominance during the initial 26 h, which gradually diminished thereafter. In the YL, the number of individuals progressively increased over time, reaching a proportion of 30.56 % at the 42-h mark. Physiological assays revealed that the YL group showed significantly enhanced total antioxidant capacity (T-AOC) along with markedly reduced malondialdehyde (MDA) levels. Furthermore, cortisol levels were significantly higher in the RL group compared to the YL, GL, and WL groups. The content of 5-hydroxytryptamine (5-HT) was significantly elevated in the RL and DA groups relative to the BL group. Histological examination indicated that cone cell density was significantly greater in the GL and WL groups than in the DA group. The retinal pigment index was highest under RL, significantly exceeding those in the GL and DA groups. Transcriptomic analysis identified 658 up-regulated and 316 down-regulated genes in the YL group compared to the DA group. KEGG enrichment analysis indicated significant activation of the neuroactive ligand-receptor interaction pathway. In summary, S. chuatsi exhibits a distinct behavioral preference for long-wavelength spectra (red and yellow light). While RL may induce chronic stress, YL effectively enhances antioxidant capacity. These findings provide a theoretical basis for the management of light environments in S. chuatsi aquaculture.

White syndrome (WS) is an emerging disease in Macrobrachium rosenbergii broodstock, closely associated with reproductive disorder. However, the mechanisms underlying WS-induced ovarian developmental arrest remain poorly understood. In this study, a combination of ovarian histology, transcriptomics, and untargeted metabolomics was employed to investigate the molecular basis of ovarian developmental arrest in WS-affected females. The WS group exhibited a significantly lower gonadosomatic index compared to the control group, accompanied by the absence of mid- and late-vitellogenic oocytes and a marked reduction in lipid deposition, indicating that ovarian redevelopment was arrested prior to or around the onset of exogenous vitellogenesis. Transcriptomic analysis identified a total of 2661 differentially expressed genes, while metabolomic analysis revealed 182 differential metabolites. Integrated analysis of the datasets demonstrated that the observed abnormalities were primarily associated with impaired lipid deposition and disturbed lipid metabolism, with further involvement of sterol utilization, redox homeostasis, and nutrient-related metabolic processes. Specifically, pathways such as arachidonic acid metabolism, vitamin digestion and absorption, and cofactor biosynthesis were identified as key pathways affected in both transcriptomic and metabolomic data. Additionally, genes such as CYP450, PLA2, NPC2, StAR, and HPGDS were suggested to play crucial regulatory roles. Overall, WS does not simply delay ovarian maturation in M. rosenbergii, but induces ovarian developmental arrest by disrupting lipid-dependent molecular processes crucial for vitellogenesis and ovarian redevelopment. These findings improve our understanding of ovarian dysfunction in WS-affected prawns and offer valuable insights for broodstock management in M. rosenbergii aquaculture.

This study investigated the interactive effects of salinity and dietary lipid source on growth, flesh quality, and lipid metabolism in juvenile largemouth bass (Micropterus salmoides). The experiment employed a 3 × 2 factorial design with three salinities (0‰, 4‰, 8‰) and two lipid sources (soybean oil and fish oil), resulting in six groups designated as S0, S4, S8 and F0, F4, F8. Fish oil improved growth performance and feed conversion, while 4‰ salinity showed comparable benefits over 8‰; these effects were additive rather than synergistic. Serum acid phosphatase and alkaline phosphatase were highest under the combination of 4‰ salinity and fish oil. Na⁺-K⁺-ATPase activity increased with salinity regardless of lipid source. Antioxidant capacity was highest in the 4‰ fish oil group, whereas oxidative stress markers were highest at 8‰. Muscle proximate composition was largely unaffected by the treatments, except that crude lipid was lower in fish oil groups and ash was higher at 8‰. Total amino acids, essential amino acids, flavor amino acids, and n-3 LC-PUFAs were enriched in the 4‰ fish oil group but depleted at 8‰. Peroxisome proliferator-activated receptor α (PPARα) expression was upregulated by salinity under soybean oil diet, while PPARγ and LPL were suppressed by fish oil. In conclusion, 4‰ salinity combined with fish oil diet improved nutritional quality and lipid metabolism, whereas 8‰ salinity was detrimental regardless of lipid source. These findings inform nutritional strategies for largemouth bass in saline-alkaline aquaculture.

This study aimed to investigate the combined effects of photoperiod (L6h: D18h, L12h: D12h, and L18h: D6h) and light intensity (200, 400, and 600 lx) on the growth performance, physiological stress, and gonadal development of mandarin fish (Siniperca chuatsi) in recirculating aquaculture systems. The results demonstrated that compared with other photoperiods, the long photoperiod was associated with reduced weight gain rate (WGR), condition factor (CF), and survival rate (SR), as well as an increased hepatic vacuolization ratio and metabolic stress. The activities of liver function-related enzymes, alkaline phosphatase (ALP) and aspartate aminotransferase (AST), were significantly influenced by the interaction of photoperiod and light intensity. Concurrently, the long photoperiod strongly directed energy allocation toward reproduction, as evidenced by significantly elevated testicular index, proportion of spermatocytes and spermatids, and intragonadal levels of testosterone (T) and estradiol (E2). The ovarian index was also regulated by photoperiod and its interaction with light intensity. In contrast, light intensity alone primarily affected alanine aminotransferase (ALT) activity and, through interaction with photoperiod, co-regulated antioxidant defense. Multi-omics analysis of testicular tissues revealed that this growth-reproduction trade-off process involved the activation of the Neuroactive ligandreceptor interaction signaling pathway and coordinated regulation of pathways including ABC transporters, Arachidonic acid metabolism, and Glycerophospholipid metabolism. In conclusion, photoperiod acts as the dominant environmental cue, whereas light intensity plays an auxiliary fine-tuning role. The long photoperiod induces energy allocation from growth toward reproduction via stress signaling. These findings provide a critical theoretical foundation for the precise management of the light environment in the recirculating aquaculture of mandarin fish.

Akirin2 is a highly conserved nuclear factor that regulates immune factor expression and has been associated with NF-κB activity in innate immune responses. The silver pomfret (Pampus argenteus), a commercial important marine fish, is susceptible to pathogens such as Cryptocaryon irritans, which causes white spot disease and immune-related tissue damage. In the present study, P. argenteus Akirin2 (PaAkirin2) was cloned from the head kidney and its function was characterized by RNA interference (RNAi) and overexpression in P. argenteus liver (PaL) cells. PaAkirin2 contained conserved nuclear localization signals and exhibited high homology with Akirin2 from related species. To assess its potential immune role, we analyzed its functional relationship with NF-κB-associated immune components including PaIL-6 and PaMyD88. LPS stimulation induced an early response of PaAkirin2 and PaIL-6 in immune tissues, with delayed induction of PaMyD88 observed in the liver. Functional studies in PaL cells demonstrated that PaAkirin2 overexpression activated NF-κB signaling, whereas its knockdown suppressed both NF-κB and PaIL-6 expression. Dual-luciferase assays confirmed that overexpression of either PaAkirin2 or PaMyD88 enhanced NF-κB-driven transcription and promoted IL-6 expression. Mutagenesis analysis identified AP-1 and NF-κB binding sites as essential for LPS-induced PaIL-6 transcription. Collectively, PaAkirin2 functions as a nuclear immunoregulator influencing NF-κB activity, directing immune defenses via transcriptional control of PaIL-6 and synergistic coordination with PaMyD88. This work provides the first mechanistic framework for Akirin2-mediated immunoregulation in teleosts, offering valuable insights for aquaculture disease management.

The large yellow croaker (Larimichthys crocea), one of the most economically valuable marine fish species in China, suffers significant economic losses in aquaculture due to infectious diseases caused by marine pathogens, such as Nocardia seriolae. The pathogenic mechanisms underlying N. seriolae infection in L. crocea and the host immune responses remain inadequately characterized. To investigate the molecular mechanisms of this infection, we conducted transcriptome sequencing on the head kidney tissues of L. crocea at 1, 3, 7, and 14 days post-infection with N. seriolae. In total, 421, 1052, 3215, and 2459 upregulated genes, along with 1853, 1777, 3718, and 3134 downregulated genes were identified, respectively. KEGG enrichment analysis revealed that differentially expressed genes were predominantly associated with immune and metabolic pathways. Notably, pathways involved in Toll-like receptor signaling, ECM–receptor interaction, cytokine–cytokine receptor interaction, and focal adhesion were significantly enriched, highlighting an immune response to N. seriolae infection in L. crocea. In addition, significant enrichment of the citrate cycle (TCA cycle) and oxidative phosphorylation pathways in metabolic processes suggests an upregulated ATP synthesis to meet the heightened energy demand associated with the immune response to infection. These findings contribute to a deeper understanding of the immune defense mechanisms in the head kidney of L. crocea against N. seriolae infection and elucidate aspects of N. seriolae pathogenicity.

The long-chain polyunsaturated fatty acids (LC-PUFA) synthesis characteristics in fish, including the identification of key genes and their functional activities, are crucial for developing targeted nutritional strategies. Although the endogenous LC-PUFA synthesis capacity of largemouth bass (Micropterus salmoides) has been preliminarily reported, the key genes involved and their functional activities remain uncharacterized. In this study, we systematically validated the LC-PUFA synthesis pathway in largemouth bass by comparing diets supplemented with LC-PUFA (LD) or non-LC-PUFA (NLD). The results demonstrated that largemouth bass can endogenously synthesize LC-PUFA from C18 PUFA, albeit with compromised growth performance and hepatic health under NLD feeding. Furthermore, we characterised the genes potentially involved in LC-PUFA biosynthesis, including two fatty acid desaturases (fads2a and fads2b) and three fatty acid elongases (elovl5, elovl4a and elovl4l). Bioinformatics analysis confirmed the evolutionary conservation of these genes and revealed the unique evolutionary divergence mechanism of the fads2s in largemouth bass. The LC-PUFA biosynthesis-related genes knockdown in primary hepatocyte and yeast heterologous expression confirmed that Fads2a has Delta 4, Delta 5, Delta 8 desaturase activities and Fads2b Delta 5, Delta 6, Delta 8 desaturase activities. And Elovl5 primarily participated in the elongation of C18 and C20 PUFA, whereas Elovl4a and Elovl4l were involved in the elongation of C18, C22 and longer-chain PUFA (> C24). Overall, we constructed a complete LC-PUFA synthesis pathway in the largemouth bass, thereby enhancing the understanding of the characteristics and evolutionary mechanisms of LC-PUFA synthesis in freshwater carnivorous fish.

In China, a newly emerging disease, White Syndrome (WS), has been identified in Macrobrachium rosenbergii. This study investigates the impact of WS, characterized by systemic whitening, abdominal muscle and hepatopancreatic atrophy, and the presence of blisters. Histopathological and transcriptomic analyses were performed on hepatopancreas and abdominal muscle tissues of affected prawns. Histological examinations revealed damaged hepatopancreatic tubules with enlarged intercellular spaces, while muscle tissues exhibited signs of atrophy. A total of 191 differentially expressed genes (DEGs) were identified from the hepatopancreas, along with 233 KEGG pathways. The primary pathways associated with WS include Lysosome, Glycosaminoglycan degradation, Pentose and glucuronate interconversions, Starch and sucrose metabolism, Biosynthesis of unsaturated fatty acids, Sphingolipid metabolism, Steroid biosynthesis, Fatty acid elongation and Retinol metabolism. Similarly, 191 DEGs were identified from the abdominal muscle, with 203 KEGG pathways. WS-related pathways included Proteasome, Glycolysis/Gluconeogenesis, and Starch and sucrose metabolism. These findings suggest that WS in M. rosenbergii may be associated with nutritional deficiencies linked to excessive reproductive activity in female prawns. This study provides critical insights for future research on WS and its management in M. rosenbergii.

This study aims to investigate the effects of dietary supplementation with protease on the growth performance, liver health, immunity, and intestinal microbiota of grass carp. Three levels of protease, 0 U/kg (P0), 6000 U/kg (P6000) and 12,000 U/kg (P12000), were formulated into diets using post-spray technology. After 9 weeks of feeding, the P6000 group had a higher weight gain rate than the P0 group, with both P6000 and P12000 groups exhibiting higher protein retention ratio and lower feed conversion ratio compared to P0. As protease levels increased, crude protein content and intestinal protease activity increased, while alkaline phosphatase (ALP) content decreased. Concurrently, the P6000 group showed higher aspartate transaminase (AST) and triglyceride (TG) levels but lower amylase content compared to P0. In terms of immune indicators, the expression levels of Intelectin and MHC-II β in the P6000 and P12000 groups were significantly lower than in P0, and IgM expression gradually increased with increasing protease levels. After challenge with Aeromonas veronii, the P12000 group showed higher survival rate. The histological results indicated that the intestinal villi length in the P6000 group was notably longer than in other groups. The intestinal microbiota analysis revealed that with increasing protease levels, Fusobacteriota abundance decreased and Actinobacteriota and Cyanobacteria abundance increased at the phylum level, while Aeromonas relative abundance decreased at the genus level. Overall, 6000 U/kg protease boosts grass carp growth and nutrient retention maximally, while 12,000 U/kg protease increases survival but may increase liver metabolic burden. Given these outcomes, the optimal protease inclusion level for grass carp aquaculture is approximately 6000 U/kg.

The silver pomfret (Pampus argenteus) is a commercially valuable marine fish species in China. Photobacterium damselae subsp. damselae (PDD) is an opportunistic pathogen in aquaculture environments and has become a serious bacterial pathogen of the aquacultural industry in recent years. In this study, two functional fragments originated from histone-derived peptides (H2A and H4) of the silver pomfret, and were identified and designated as spH2A.2 and spH4. In addition, the full-length cDNA of H2A from silver pomfret (SPH2A) consists of 387 base pairs (bp) coding sequence (CDS) that encodes 128 amino acids (aa), while the full-length cDNA of SPH4 consists of 312 bp CDS and encodes 103 aa. Tissue distribution analysis showed that SPH2A had a higher expression pattern in the head kidney and intestine, while SPH4 was mainly expressed in the spleen. After PDD infection, both histone gene expression levels were significant upregulated at 1 day post-infection (dpi) (P < 0.01) in the liver. Furthermore, spH4 and spH2A.2 peptides had potent antimicrobial activity against Gram-negative bacteria, with the MIC value ranging from 24 to 95 µM and 66–133 µM, respectively. Cytotoxicity of spH4 and spH2A.2 was tested in silver pomfret primary cells (liver, spleen and head kidney), and the results showed that spH4 had no cytotoxicity, while spH2A.2 displayed cytotoxic activity on silver pomfret cells. Additionally, scanning electronic microscope (SEM) analysis revealed that spH4 and spH2A.2 could destroy the PDD cell wall structure. Overall, the spH4 and spH2A.2 peptides were likely prone to exert the antimicrobial activity and may be useful to defend against PDD in silver pomfret aquaculture.

The cultivation of largemouth bass (Micropterus salmoides), a species of significant economic value in aquaculture, has experienced notable growth recently. However, the deterioration of water quality seriously affects the metabolic responses of M. salmoides. While compound microbial agent (CMA) is widely utilized for ecological rehabilitation and water filtration, its application in M. salmoides has not been reported. Here, based on physio-biochemical tests and 16S rRNA sequencing, we investigated the effects of CMA (yeast, Bacillus subtilis, and lactic acid bacteria) on the water quality within the recirculating aquaculture system, along with physiological indices and gut microbiota of M. salmoides. Compared to the control and single microbial agent (yeast), CMA treatment improved the water quality by improving the dissolved oxygen and delaying the increase of pH, total nitrogen, total phosphorus, ammonia nitrogen, and nitrite. The 16s rRNA gene sequencing revealed that the water treated with CMA exhibited elevated levels of chao1, Shannon, Pd, and a larger population of dominant bacterial. Besides, higher values of ACE, chao1, Shannon, and OTU level, and lower Simpson index were found in CMA treated M. salmoides samples, suggesting that CMA treatment enhanced the species richness and diversity of gut microbiota of M. salmoides. Furthermore, CMA treatment hindered the generation and proliferation of harmful bacteria, such as the Mycoplasma mobile 163K species and the Erysipelotrichaceae family, which was associated with enhanced antioxidant enzymatic activity and decreased MDA level in both the serum and liver. These findings shed light on the essential roles of CMA in M. salmoides culturing and introduce an innovative approach to enhance the aquatic environment.

Photobacterium damselae subsp. damselae (PDD) is a pathogenic bacterium with wide distribution, a broad spectrum of host infection, and a high mortality rate in infected animals. Therefore, it is considered one of the most dangerous pathogenic bacterial species in mariculture worldwide. Among the current alternative aquatic disease preventive therapies, phage therapy has attracted widespread attention due to its strong specificity, fast effects, non-toxicity, and lack of pollution. In this study, we identified a bacteriophage that can specifically lyse PDD in the silver pomfret culture environment. The genetic material of the bacteriophages was confirmed to be DNA. Additionally, we studied the effects of bacteriophages under different environmental conditions. Furthermore, we also conducted treatment experiments on silver pomfret using this bacteriophage, and the results showed that the phage had a certain protective effect on silver pomfret infected with PDD. In summary, we isolated and screened a bacteriophage with relatively stable biological properties against PDD, providing a certain theoretical basis for preventive strategies against PDD infection in silver pomfret mariculture.

Galectin-3, as a unique member of the galectin family, exhibits a significant role in both extracellular and intracellular environments. In this study, the silver pomfret galectin-3 gene (SpGal-3) was cloned and functionally characterized. The open reading frame of SpGal-3 was found to be 843 base pairs in length, encoding a protein of 280 amino acids. Phylogenetic tree analysis indicated that SpGal-3 was highly conserved in fish species. The mRNA of SpGal-3 was expressed at various levels in all tested tissues, with the gill exhibiting the highest expression levels. Furthermore, infection with Photobacterium damselae subsp. damselae significantly changed the mRNA expression of SpGal-3 in liver and head kidney tissues. Subcellular localization analysis suggested that SpGal-3 was expressed in both the nucleus and cytoplasm. Purified recombinant protein of SpGal-3, designated as rSpGal-3, showed binding ability to two classic pathogen-associated molecular patterns (peptidoglycan and lipopolysaccharide) and two sugars (D-mannose, and D-galactose), with the highest affinity toward lipopolysaccharide. Additionally, rSpGal-3 demonstrated the capability to interact with various bacterial species. Taken together, our findings underscore the critical role of SpGal-3 as a key pattern recognition receptor in the immune response of the silver pomfret.

In this study, we conducted a 16-week feeding trial to investigate the effects of a high-cassava starch diet on growth performance, liver function, and metabolism in largemouth bass (Micropterus salmoides). We formulated five diets containing varying levels of cassava starch: 12%, 9%, 6%, 3%, and 0% (termed M12, M9, M6, M3, and M0, respectively). We distributed these diets among largemouth bass with the initial body weight of 83.33 ± 0.55 g via an in-pond “raceway” aquaculture system. Our findings suggest that high level (12%) of cassava starch dietary inclusion adversely affected growth performance metrics such as weight gain rate and specific growth rate, along with feed utilization efficiency indicators, including protein efficiency, protein deposition rate, and the apparent digestibility of dry matter and protein. This negative impact was accompanied by a decrease in intestinal amylase activity. Through further transcriptomic analysis, we identified several key genes associated with carbohydrate metabolism, which underwent changes influencing liver function. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis revealed the involvement of these differentially expressed genes (DEGs) in the tricarboxylic acid cycle (TCA cycle). Comparative metabolomics analysis further indicated that the M9 group showed significant enrichment in pathways related to amino acid metabolism and alterations in the levels of metabolites involved in carbohydrate metabolism. In conclusion, our study demonstrates that incorporating up to 9% cassava starch in the diet can enhance growth performance in largemouth bass by stimulating digestive enzyme activities and promoting glucose utilization.

Acrossocheilus fasciatus (Cypriniformes, Cyprinidae) is emerged as a newly commercial stream fish in the south of China with high economic and ornamental value. In this study, a chromosome-level reference genome of A. fasciatus was assembled using PacBio, Illumina and Hi-C sequencing technologies. As a result, a high-quality genome was generated with a size of 879.52 Mb (accession number: JAVLVS000000000), scaffold N50 of 32.7 Mb, and contig N50 of 32.7 Mb. The largest and smallest scafford was 60.57 Mb and 16 kb, respectively. BUSCO analysis showed a completeness score of 98.3%. Meanwhile, the assembled sequences were anchored to 25 pseudo-chromosomes with an integration efficiency of 96.95%. Additionally, we found approximately 390.91 Mb of repetitive sequences that accounting for 44.45% of the assembled genome, and predicted 24,900 protein-coding genes. The available genome reported in the present study provided a crucial resource to further investigate the regulation mechanism of genetic diversity, sexual dimorphism and evolutionary histories.

Interleukin-11 (IL-11) is a versatile cytokine that modulates cellular differentiation and proliferation in various cell types and tissues. In this study, IL-11 gene from goldfish (Carassius auratus L.) has been identified and characterized. Goldfish IL-11 (gfIL-11) has an open reading frame (ORF) that spans 591 base pairs (bp). The ORF encodes a precursor protein consisting of 196 amino acids (aa), which includes a 26 aa signal peptide and a conserved domain belonging to the IL-11 superfamily. Based on phylogenetic analysis, gfIL-11 was found to be closely related to other IL-11 homologues identified in various fish species. The gfIL-11 transcript exhibited varied expression levels across all the analyzed tissues, with the highest expression observed in the gill and spleen. Treatment of goldfish head kidney leukocytes (HKLs) with LPS and live Aeromonas hydrophila, increased gfIL-11 mRNA expression level. Recombinant gfIL-11 protein (rgIL-11) induced a dose-dependent production of TNF-α and IFNγ from goldfish HKLs. Furthermore, the administration of rgIL-11 to goldfish HKLs triggered an increase in the expression of various transcription factors such as MafB, cJun, GATA2, and Egr1, which play a vital role in the differentiation of myeloid precursors into macrophages and monocytes. Our findings provide evidence that IL-11 is a crucial cytokine that promotes cell proliferation, immune response, and differentiation across various hematopoietic lineages and stages of goldfish.

Granulocyte colony-stimulating factor (GCSF) is a member of the hematopoietic growth factor family that acts primarily on neutrophils and neutrophilic precursors to promote cell proliferation and differentiation. Although multiple GCSF genes have been found in teleosts, knowledge of their functions during fish hematopoietic development is still limited. Here, we report for the first time the molecular and functional characterization of two goldfish GCSFs (gfGCSF-a and gfGCSF-b). The open reading frame (ORF) of the gfGCSF-a and gfGCSF-b cDNA transcript consisted respectively of 624 bp and 678 bp with its ORF encoding 207 and 225 amino acids (aa), with a 17 aa signal peptide for each gene and a conserved domain of the IL-6 superfamily. Treatment of goldfish head kidney leukocytes (HKLs) with LPS increased gfGCSF-a and gfGCSF-b mRNA expression levels, also exposure of HKLs to either heat-killed or live A. hydrophila, induced transcriptional upregulation of gfGCSF-a and gfGCSF-b levels. Recombinant gfGCSF-a and gfGCSF-b protein (rgGCSF-a and rgGCSF-b) induced a dose-dependent production of TNFα and IL-1β from goldfish neutrophils. In vitro experiments showed rgGCSF-a and rgGCSF-b differentially promoted the proliferation and differentiation of leukocytes in goldfish. Furthermore, treatment of HKLs with rgGCSF-a showed significant upregulation of mRNA levels of the hematopoietic transcription factor GATA2, Runx1, MafB, and cMyb, while gfGCSF-b induces not only all four transcriptional factors mentioned above but also CEBPα. Our results indicate that goldfish GCSF-a and GCSF-b are important regulators of neutrophil proliferation and differentiation, which could stimulate different stages and lineages of hematopoiesis.

Nigericin has been reported to induce apoptosis and pyroptosis in mammalian models. However, the effects and mechanism underlying the immune responses of teleost HKLs induced by nigericin remain enigmatic. To decipher the mechanism after nigericin treatment, the transcriptomic profile of goldfish HKLs was analyzed. The results demonstrated that a total of 465 differently expressed genes (DEGs) with 275 up-regulated and 190 down-regulated genes were identified between the control and nigericin treated groups. Among them, the top 20 DEG KEGG enrichment pathways were observed including apoptosis pathways. In addition, the expression level of selected genes (ADP4, ADP5, IRE1, MARCC, ALR1, DDX58) by quantitative real-time PCR showed a significant change after treatment with nigericin, which was generally identical to the expression patterns of the transcriptomic data. Furthermore, the treatment could induce cell death of HKLs, which was confirmed by LDH release and annexin V-FITC/PI assays. Taken together, our results support the idea that nigericin treatment might activate the IRE1-JNK apoptosis pathway in goldfish HKLs, which will provide insights into the mechanisms underlying HKLs immunity towards apoptosis or pyroptosis regulation in teleosts.

为进一步了解浙江省马口鱼的种质资源现状和人工繁殖对群体遗传多样性的影响,通过对瓯江(OJ)和钱塘江(QT)的野生群体以及八里店(BL)养殖群体的线粒体Cyt b基因进行扩增和测定,获得了编码Cyt b基因的1140 bp序列与GenBank中已有的236个个体的序列进行综合分析,共检测出288个变异位点,界定了136种单倍型,其中瓯江、钱塘江和八里店群体单倍型数目分别为1、10和6.钱塘江群体的单倍型多样性和核苷酸多样性分别为0.716和0.01616,八里店群体分别为0.607和0.01205.分子方差分析(AMOVA)显示,遗传变异主要来源于群体间(55.06％),少数来自群体内(44.94％),群体间遗传分化均达到显著水平(P<0.05).八里店群体亲本源于钱塘江,但经过数代人工繁殖后其遗传多样性有所降低.基于邻接法构建的系统发育树显示,钱塘江群体可以分为3支,1支与长江水系湖南采集的单倍型聚为一支,63.64％的钱塘江个体属于这一支;1支与珠江水系广西采集的单倍型聚为一支,9.38％的个体属于这一支,剩下的样本和浙江瓯江采集的样本聚为一支.这说明钱塘江群体的祖先来源有一定的复杂性.本研究结果可为马口鱼种质资源的保护和利用提供数据支持.