Search Results (18)

To address cryodamage in Culter alburnus sperm, this study evaluated the effects of trehalose supplementation in a conventional cryomedium (D-15 + 10% ethylene glycol). Six experimental groups were established: fresh sperm (G1), a conventional cryomedium (G2), groups supplemented with 10, 100, or 200 mmol/L trehalose (G3–G5), and a control group with extender only (G6). The group with 100 mmol/L trehalose (G4) was associated with improved post-thaw motility parameters (activation rate, movement time, and lifespan) and higher antioxidant (superoxide dismutase and catalase) and energy metabolism (ATPase, succinate dehydrogenase, lactate dehydrogenase) enzyme activities. Ultrastructural damage in G4 included partial plasma membrane rupture and mitochondrial swelling, while G6 exhibited additional damage features including membrane disintegration, mitochondrial disruption, and flagellar fracture. Proteomic analysis revealed that, compared to G1, G4 exhibited higher abundance of proteins (e.g., Histone H2A, cytochrome c oxidase, profilin) involved in structural integrity and energy homeostasis, whereas G6 showed signatures of oxidative stress and metabolic dysfunction (lower abundance of NADH dehydrogenase and higher abundance of calcium-transporting ATPase and glutathione S-transferase). In conclusion, 100 mmol/L trehalose was associated with improved cryopreservation outcomes, and the proteins identified provide a basis for further investigation. This approach offers a framework for refining germplasm conservation strategies in aquaculture. Full article

Ongoing urbanization continuously reshapes water quality, habitat structure, and biological communities in river ecosystems; however, its impacts on host-associated microbial communities remain poorly documented. The fish gut microbiota, a critical interface between the aquatic environment and host physiology, is widely recognized as an integrative indicator of both environmental change and host ecological traits. This study established a continuous urbanization gradient along Shanghai’s Suzhou River, spanning from suburban areas through the outer and inner ring roads to the city center. Five common wild fish species (Coilia nasus, Hemiculter bleekeri, Culter alburnus, Acheilognathus macropterus, and Pseudorasbora parva) were collected, and their gut microbiota were characterized via high-throughput 16S rRNA gene sequencing. Significant variation in OTU richness, alpha diversity, and community structure was observed across urbanization gradients and among fish species. Principal coordinate analysis revealed that samples from suburban areas were structurally distinct from those collected in other zones, whereas inner-ring and urban-core areas exhibited substantial compositional overlap. Taxonomic analysis revealed that Firmicutes and Pseudomonadota dominated all samples; however, their relative abundances and genus-level composition varied considerably among fish species and across the urbanization gradient. PICRUSt-based functional prediction indicated that metabolic pathways predominated, particularly those involved in global and overview maps, carbohydrate metabolism, amino acid metabolism, energy metabolism, and metabolism of cofactors and vitamins. Collectively, these findings demonstrate that fish gut microbial communities exhibit spatial structuring along the urbanization gradient, with species-specific responses linked to ecological traits. This study provides valuable data on host-associated microbial communities in urban rivers and offers a reference for incorporating microbial indicators into urban water ecological assessments. Full article

Live fish transport easily induces severe physiological stress, marked by pronounced oxidative damage and significant mortality, leading to substantial economic losses annually. Here, we evaluated the effects of taurine intake on alleviating stress response during transportation of Culter alburnus. Juvenile fish were fed diets containing 0 (control), 0.5, 1.0, 1.5, or 2.0 g/kg taurine for 8 weeks before undergoing 12 h of simulated transport. The results showed that taurine supplementation significantly improved growth performance in a dose-dependent manner. During transportation, the deterioration of water quality and the damage of gill tissue decreased with the increase in concentration. The determination of catalase (CAT), glutathione peroxidase (GSH-Px) and malondialdehyde (MDA) showed that 2.0 g/kg taurine improved antioxidant capacity. The high-concentration taurine group enhanced the activities of immune enzymes such as acid phosphatase (ACP) and alkaline phosphatase (AKP), while the activity of total nitric oxide synthase (T-NOS) was inhibited. The antioxidant immune effect of the 0.5 g/kg and 1.0 g/kg concentration groups was not obvious. Transcriptome analysis revealed that 2.0 g/kg taurine enhanced the antioxidative stress capacity of C. alburnus by upregulating the expression of immune-related genes (TLR5, Il12b) and activating the Toll-like receptor signaling pathway as well as the cytokine–cytokine receptor interaction pathway. These findings demonstrated that dietary taurine improved resilience to transport stress in C. alburnus. Full article

Aiming to understand the genetic diversity of Culter and Cultrichthys fishes in West Dongting Lake following the implementation of fishing ban, this study analyzed the genetic diversity and phylogeny of five Cultrinae species based on mitochondrial Cytb and COI gene sequences. For Cytb, 50 haplotypes were identified with high overall genetic diversity (H_d = 0.954, π = 0.04765, K = 53.506). Similarly, COI yielded 48 haplotypes (H_d = 0.950, π = 0.03251, K = 36.414). Interspecific comparisons revealed that Culter mongolicus and Culter alburnus exhibited the highest genetic diversity, while Cultrichthys erythropterus showed the lowest. Demographic inferences from neutrality tests and mismatch distribution analyses differed between markers. Based on Cytb, populations of C. erythropterus and C. oxycephaloides appeared to be at neutrality, whereas C. mongolicus, C. alburnus, and C. dabryi significantly deviated, suggesting historical expansion. Mismatch distributions supported recent expansion in C. mongolicus and C. dabryi. In contrast, COI-based neutrality tests indicated expansion in C. mongolicus, C. alburnus, and C. dabryi, with mismatch results confirming this signal for C. dabryi. The negative values of Tajima’s D and Fu’s Fs observed across all five species reflect an accumulation of low-frequency alleles within populations, which may indicate a recent rapid demographic recovery. These findings provide genetic evidence that the genetic diversity of these Cultrinae species has likely been recovering since the fishing ban took effect on 1 January 2020. Further conservation strategies are therefore recommended to promote population recovery and enhance genetic diversity. Full article

Culter alburnus (topmouth culter, TC) is extensively distributed in various rivers and lakes in China. As a widely adaptive fish species, they have significant economic value and special ecological roles. Intergeneric hybridization is a pivotal strategy for generating novel hybrid lineages and species. In a previous study, we obtained an improved bisexual hybrid culter, BTBTF₁, derived from the hybrid lineage of Megalobrama amblycephala (blunt snout bream, BSB, 2n = 48, ♀) × Culter alburnus (2n = 48, ♂). In this study, we established an improved hybrid culter lineage by the self-crossing of BTBTF₁ and evaluated the biological characteristics regarding cytology, morphology, and genetics. DNA content and chromosome analyses confirmed that BTBTF₁-F₂ was a diploid lineage (2n = 48), with morphological traits exhibiting intermediate values between parental species, except for significantly TC-biased full-length-to-body length (FL/BL) and body length-to-head length (BL/HL) ratios (p < 0.05). ITS sequencing analysis revealed that BTBTF₁-F₂ inherited ITS1 sequences from BSB and TC. The global methylation level in BTBTF₁-F₂ was substantially reduced compared to progenitors, characterized by elevated full and diminished hemimethylation states. Transcriptomic analysis identified 7877 differentially expressed genes (DEGs), displaying 9.05%/8.30% maternal (BSB)-dominant and 17.01%/18.95% paternal (TC)-dominant expression patterns in BTBTF₁ and F₂. Remarkable intergenerational similarity in phenotypic and molecular profiles, coupled with bidirectional inheritance of progenitor characteristics, confirmed BTBTF₁-F₂ as a genetically stable allodiploid lineage. Remarkably, methylation patterns, and DEG expression collectively demonstrated significant TC-oriented bias (p < 0.05). This study reports a novel stabilized allodiploid culter lineage after a comprehensive assessment at cytology, morphology, and genetic levels, and provides new insights into genetic bias in hybrid progeny. Full article

Standardized fishing gear represents a common fisheries management intervention, yet its effectiveness in multi-species freshwater ecosystems remains insufficiently assessed. This study presents the first application of the Length-Based Bayesian Biomass (LBB) method to systematically evaluate the stock status of eight major commercial fish species in Xingkai Lake (located within China). Length-frequency data collected in 2019 (marking the policy initiation) and 2024 (after five years of implementation) were used to estimate key population parameters and exploitation indicators. The results revealed that the four species (Carassius gibelio, Acheilognathus macropterus, Hemiculter lucidus, and Hemiculter leucisculus) recovered to healthy status (B/B_MSY ≥ 1.0), demonstrating the policy’s effectiveness for small-bodied, fast-growing species. In contrast, three species (Chanodichthys abramoides, Chanodichthys mongolicus, and Chanodichthys erythropterus) remained grossly overfished (B/B_MSY < 0.5), while Culter alburnus experienced increased fishing pressure, indicating limited efficacy for larger, slow-growing species with collapsed initial stocks. Although the mesh size increase facilitated recovery of specific populations, fisheries resources in Xingkai Lake continue to face overfishing pressure. Management strategies lacking an ecosystem perspective may not only fail to achieve conservation objectives but could also trigger ecological risks. This study underscores that ecosystem-based management is essential for sustainable management of multi-species fisheries. Full article

Grass carp (Ctenopharyngodon idella) is one of the most economically important cyprinid species cultured in China. The diploid gynogenetic grass carp (2nGGC, 2n = 48) was generated from the hybrid of female grass carp (GC, 2n = 48) and male topmouth culter (TC, 2n = 48, Culter alburnus). This study obtained the full-length transcriptome of 2nGGC from five tissues using Pacific Biosciences (Pacbio) single-molecule real-time long-read isoform sequencing. Following the mapping of long reads to GC and TC reference genomes, a total of 1848 fusion isoforms were identified. Among them, 775 were distributed across different genomes, indicating that chimeric DNA fragments of TC were embedded in the 2nGGC genome. After removing the fusion genes and redundant isoforms, 107,721 full-length transcripts were obtained from 2nGGC, providing important full-length reference sequences for further research. Finally, comparative analysis of homologous gene variation identified 34 fragments in 2nGGC containing recombinant SNPs derived from both GC and TC. These results provide evidence that natural gynogenesis represents a form of “micro-hybridization” characterized by heterogeneous DNA fragments, distinct from traditional hybridization involving chromosome-level recombination. These findings offer valuable reference for fish genetic breeding. Full article

The Xingkai Lake topmouth culter (Culter alburnus) is an endemic, economically valuable fish in Heilongjiang that is highly sensitive to ammonia. However, the systemic effects of acute ammonia stress on its liver have not been determined. The objective of this study was to elucidate the changes in and relationships among stress biomarkers, antioxidant defense mechanisms, apoptosis indicators, and histopathological alterations in the liver of C. alburnus, a fish species native to Xingkai Lake, China, under acute ammonia exposure. Guided by the findings of a 96 h-LC₅₀ assay, the researchers subjected the fish to 48 h of acute exposure at specified total ammonia nitrogen (TAN) concentrations of 30 mg/L, 36 mg/L, and 40 mg/L. A comprehensive assessment of physiological and biochemical markers, including cortisol (COR), blood ammonia (Amm), blood glucose (Glu), aspartate aminotransaminase (AST), alanine aminotransaminase (ALT), catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), and malondialdehyde (MDA), revealed pronounced physiological stress and oxidative damage, particularly in the high-concentration groups. The physiological effects of ammonia exposure on C. alburnus showed a clear concentration and time dependence. Notably, elevated ammonia levels significantly upregulated apoptosis-associated genes such as P53, Bax, and Caspase-3. These findings were further substantiated by terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) assays and histopathological examinations. Overall, the study demonstrated that acute ammonia exposure exerted substantial impacts on the physiological, biochemical, and genetic expression profiles of C. alburnus in Xingkai Lake, leading to sustained stress and oxidative damage, especially at elevated concentrations (30–40 mg/L). Full article

The novel hybrid fish BTB, derived from crossing blunt snout bream (Megalobrama amblycephala, BSB) and topmouth culter (Culter alburnus, TC), exhibits markedly hypoxia tolerance in aquaculture. In this study, hypoxic treatment experiments confirmed that, comparing to its original parent BSB, the tolerance to low oxygen of BTB increased by 20.0%. Furthermore, a comparative analysis of the transcriptome and metabolome was performed using gill tissues from BTB exposed to normoxic and hypoxic conditions. Under hypoxic conditions, BTB displayed adaptive modifications in gill lamellae and hemocytes. Transcriptomic profiling identified 789 differentially expressed genes (DEGs), with 298 upregulated and 491 downregulated, enriched in pathways including apoptosis, NK cell-mediated cytotoxicity, MAPK/TNF/Toll-like receptor signaling, and HIF-1/FoXO signaling pathways. Twelve hypoxia-related candidate genes (egln3, im_7150988, znf395a, hif-1an, mknk2b, pck2, ero1a, igfbp-1a, vhl, bpifcl, egln1a, and ccna1) were screened and validated as potential contributors to hypoxia tolerance. Metabolomics analysis revealed a total of 108 differential metabolites (78 upregulated and 30 downregulated), predominantly linked to Arginine and proline metabolism, Ether lipid metabolism, Arachidonic acid metabolism, and Glycerophospholipid metabolism. Association analysis of transcriptomics and metabolomics revealed that the DEGs and DMs were enriched in the pathways of glycerophospholipid metabolism, ether lipid metabolism, arachidonic acid metabolism, and arginine and proline metabolism. In summary, BTB exhibited relatively high hypoxia tolerance, and 12 candidate genes related to hypoxia tolerance were identified. These findings laid a foundation for further investigation into the mechanisms of hypoxia tolerance improvement in hybrid fish. Full article

Olfaction plays a crucial role in fish feeding behaviors and ecological adaptation. However, systematic studies on its transcriptional regulation and molecular evolutionary mechanisms in herbivorous and carnivorous fishes remain scarce. In this study, we analyzed four Xenocyprididae species: two herbivorous (Ctenopharyngodon idella and Megalobrama amblycephala) and two carnivorous (Elopichthys bambusa and Culter alburnus), using olfactory rosette transcriptome sequencing and cross-species comparisons. The number of unigenes per species ranged from 40,229 to 42,405, with BUSCO completeness exceeding 89.2%. Functional annotation was performed using six major databases. Olfactory-related candidate genes were identified based on Pfam domains (7tm_4) and KEGG pathways (ko04740), revealing 8–19 olfactory receptor genes per species. These candidate genes were predominantly enriched in the olfactory transduction and neuroactive ligand–receptor interaction pathways. A total of 3681 single-copy orthologous genes were identified, and their expression profiles exhibited clear interspecific divergence without forming strict clustering by dietary type. High-threshold differentially expressed trend genes (|log₂FC| ≥ 4) were enriched in pathways related to RNA processing, metabolite transport, and xenobiotic metabolism, suggesting that the olfactory system may participate in diverse adaptive responses. Ka/Ks analysis indicated that most homologous genes were under purifying selection, with only 0.87–2.07% showing positive selection. These positively selected genes were enriched in pathways related to immune response and neural regulation, implying potential roles in adaptive evolution associated with ecological behavior. Furthermore, the olfactory-related gene oard1 exhibited Ka/Ks > 1 in the E. bambusa vs. C. idella comparison. qRT-PCR validation confirmed the reliability of the RNA-Seq data. This work is the first to integrate two complementary indicators—expression trends and evolutionary rates—to systematically investigate the transcriptional regulation and molecular evolution of the olfactory system in Xenocyprididae species under the context of dietary differentiation, providing valuable reference data for understanding the perceptual basis of dietary adaptation in freshwater fish. Full article

Spawning diversity plays an essential role in fish survival and reproduction, which contributes to the exceptional diversity of teleosts among vertebrates. Different zona radiata structures reflect the adaptability of fish to the environment of spawning and early embryonic development. The morphological and transcriptional characteristics of fish follicle development between different spawning habits, particularly the zona radiata variations, have been poorly documented. In this study, we integrated histology and transcriptomics to investigate the differences in the zona radiata structure and gene expression profiles among follicles from different spawning habits of Culter alburnus. Our results revealed that stage Ⅲ was the crucial period for zona radiata thickening and structure differentiation. Transcriptomic analyses of adhesive and semi-buoyant eggs at stage Ⅲ revealed a significant upregulation of genes involved in glycoprotein synthesis, extracellular matrix formation, and regulation of protease activity in adhesive eggs, such as the wfdc and a2ml gene family. This upregulation likely underpins the thicker zona radiata in adhesive eggs, facilitating their attachment to substrates. This study represents the first elucidation of the ultrastructure of the zona radiata and gene expression patterns in different developmental stages of adhesive and semi-buoyant eggs of Culter alburnus, offering new perspectives for aquaculture research in understanding fish reproductive adaptations. Full article

Cell-cultured meat production relies on stable, proliferative seed cells, commonly sourced from muscle satellite cells (MuSCs) and adipose-derived mesenchymal stem cells (AD-MSCs). However, establishing such cell lines in fish species remains technically challenging. While pluripotent stem cells (e.g., ESCs/MSCs) offer alternatives, their differentiation efficiency and predictability are limited. Here, we developed TCCF2022, a novel caudal fin-derived cell line from Topmouth culter (Culter alburnus), which expresses pluripotency markers (AP, Oct4, Sox2, Klf4, and Nanog) and aggregated growth to form 3D spheroids. Forskolin supplementation enhanced pluripotency maintenance. The presence of adipogenic and myogenic lineage cells within the 3D spheroids was confirmed, demonstrating their potential as seed cells for cell-cultured meat. Using a small-molecule cocktail 5LRCF (5-Azacytidine, LY411575, RepSox, CHIR99021, and Forskolin), we successfully differentiated TCCF2022 cells into functional myotubes. Additionally, we established a method to induce the differentiation of TCCF2022 cells into adipocytes simultaneously. Thus, the TCCF2022 cell line can be used to improve muscle fiber formation and lipid composition, potentially enhancing the nutritional profile and flavor of cultured fish meat. Full article

To study the genetic diversity of Culter alburnus (C. alburnus) populations, we analyzed the genetic diversity of five C. alburnus populations from Songhua Lake (SH), Huaihe River (HH), Changjiang River (CJ), Taihu Lake (TH), and Gehu Lake (GH) based on mitochondrial COI gene sequences. The results showed that the average contents of bases T, C, A, and G in the 526 bp COI gene sequence were 25.3%, 18.1%, 28.1%, and 28.6%, respectively, which showed AT bias. A total of 115 polymorphic sites were detected in the five populations, and 11 haplotypes (Hap) were defined. The nucleotide diversity (P_i) of the five populations ranged from 0.00053 to 0.01834, and the haplotype diversity (H_d) ranged from 0.280 to 0.746, with the highest genetic diversity in the TH population, followed by the SH population, with lower genetic diversity in the HH, CJ and GH populations. The analysis of the fixation index (Fst) and the genetic distance between populations showed that there was significant genetic differentiation between the SH population and the other populations, and the genetic distances between all of them were far; the genetic diversity within populations was higher than that between populations. Neutral tests, mismatch distributions, and Bayesian skyline plot (BSP) analyses showed that the C. alburnus populations have not experienced population expansion and are relatively stable in historical dynamics. Full article

The removal of the net enclosure has been used as a lake management strategy in various regions of China as ecological development is given more attention. Nevertheless, little is known about the substantive impact of this measure on fish communities in inland lakes. To this end, the fish community composition and structural features after the removal of the net enclosure in Gehu Lake were explored and evaluated in this study from 2021 to 2022 and compared to the investigation before the net enclosure removal from 2017 to 2018. Belonging to 7 orders, 10 families, and 46 species, a total of 17,151 fish were collected, with pelagic, sedentary, and omnivorous species dominating. In comparison, the number of species increased by 10 after removal, and fish alpha diversity increased. The Index of Relative Importance (IRI) revealed that the composition of dominating species remained constant, including Coilia nasus, Hypophthalmichthys molitrix, and Hypophthalmichthys nobilis; Parabramis pekinensis, Megalobrama amblycephal, and Culter mongolicus were upgraded from common species to general species. Culter alburnus, Hemiculter bleekeri, and Pseudobrama simoni were downgraded from general species to common species. Elopichthys bambusa had become a common species (IRI = 109.35), which was not discovered before removal. According to the hierarchical clustering (HC) and non-metric multidimensional sequencing (NMDS), the fish community of the northern reserve was highly aggregated. As the Abundance Biomass Comparison (ABC) curve and biodiversity index indicated, the fish community structure of the whole lake was in a state of moderate anthropogenic disturbance with reduced stability, while that of the northern reserve was in a state of light anthropogenic disturbance with greater stability. The number of fish species increased in this survey compared to the period before removal, species and dominant species composition altered dramatically, and total lake stability declined. This study demonstrates that the fish diversity in Gehu Lake increased after the removal of the net enclosure. Meanwhile, the stability of the fish community structure was decreased temporarily. Lake restoration is a long-term process, and the underlying impact of the removal of the net enclosure still requires continuous monitoring and further studies. Full article

Geographical populations of Culter alburnus inhabiting different regions of China present substantial differences in their reproduction and development characters. This study compared the intestinal structures, digestive enzyme activities, and intestinal microbiomes in the Xingkai (XK) Lake and the Dianshan (DS) Lake populations of C. alburnus collected in two isolated and contrasting river systems. We wanted to discover whether the intestinal structure and functional divergence were formed in the two populations due to adaptive evolution caused by geographical isolation. Our study indicated that higher intestinal villi, thicker intestinal mucosa layer and intestinal muscle layer, and significantly higher activity of α-amylase were identified in the XK population. Moreover, quite different intestinal microbiomes were presented in the two populations, with the higher abundance of Bacteroidetes and Firmicutes in the XK population. The significantly different intestinal microbiome in the XK population was functionally enriched in carbohydrate, lipid, and amino acid metabolism by Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis. Our findings indicated that substantial adaptative divergence in the intestinal structures and intestine microbiomes was formed in the two populations due to long-term geographical isolation, which may have strongly affected the digestion and absorption ability of the XK population compared with the DS population. Full article