Fish Physiology and Biochemistry最新文献

Improving farmed fish carbohydrate utilization reduces the feed fish meal level and lessens water pollution. Herein, the effects of glycerol kinase (gyk) and forkhead box (fox)-q1 on Micropterus salmoides glucose homeostasis were investigated, and a growth-linked marker in gyk on a carbohydrate-rich diet was developed. The data showed that gyk and foxq1 expression is negatively correlated with plasma glucose level. Although gyk and foxq1 showed no effect on plasma triglyceride, cholesterol, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, hepatic triglyceride, and muscular triglyceride content, positive regulation of insulin secretion, hepatic glycogen, and muscular glycogen level was observed. Overexpression and shRNA-mediated knockdown assays indicated that gyk and foxq1 positively regulate hepatic and muscular gene expression involved in triglyceride synthesis (fatty acid synthetase, acetyl-CoA carboxylase), glycolysis (phosphofructokinase, glucokinase), glycogen synthesis (glycogen synthase), and pentose phosphate pathway (glucose-6-phosphate dehydrogenase), but negatively regulate gluconeogenesis gene (phosphoenolpyruvate carboxykinase, glucose-6-phosphatase). In vitro, - 1652 ~  - 2056 bp was determined to be the core promoter sequence of gyk using progressive deletion. Luciferase activity showed that gyk promoter activity decreased following foxq1 binding site mutation in this sequence, and it was enhanced by foxq1 overexpression. Moreover, foxq1 inhibition attenuated hypoglycemia induced by gyk overexpression, and its suppression relieved the increase in gyk-mediated plasma glucose. Besides, an insertion-deletion marker located at rs16857996 in gyk was developed. Individuals without deletion (aaaac) of this site had higher body weight, full length, and body length. This regulatory axis provides a theoretical target and breeding indicator for increasing carbohydrate utilization and reducing the dietary fish meal in M. salmoides.

Cell culture plays a crucial role in various fields of life science research such as cancer, immunology, and virology. Numerous cell lines have been established in mammals, while fish cell lines remain comparatively limited in number. This study established a spontaneously immortalized cell line from the muscle of red sea bream, Pagrus major, which is a commercially important fish in Japan. Primary cells were isolated from muscle tissue using 0.2% collagenase and cultured in Leibovitz's L-15 medium without CO₂. The cells required fetal bovine serum in a dose-dependent manner at 28 °C for optimal growth. The cells were also able to grow in F12 medium, but not in Dulbecco's modified Eagle's medium. RNA-sequencing analysis raised the possibility that myosatellite cells/myoblasts in primary culture would gradually be replaced with fibroblasts or epithelial-like cells with an increasing number of passages because collagen-related genes were expressed more than in muscle tissue. Upon serum starvation, the cells differentiated into adipocyte-like cells because of slight lipid accumulation. Therefore, the established cells were considered to lack myogenic potential. In conclusion, we established the Nagasaki University Fisheries-P. major 1 (NUF-PM1) cell line, which consisted of fibroblast/epithelial-like cells, but not myosatellite cells/myoblasts, from the muscle of P. major, and we observed the cells over 80 passages. This study adds to the limited number of fish cell lines available for research, which can be used to develop fish cultured meat and as a model for fish adipocyte differentiation.

Myocyte Enhancer Factor 2 (Mef2) is a transcription factor that exert crucial functions in muscle cells, neurons and other cell types. These Mef2 family members modulate the expression of target genes to participate in a broad spectrum of biological processes, such as, but not restricted to, muscle differentiation and heart development. Myostatin (mstn), a protein from the Transforming Growth Factor-β (TGF-β) superfamily, is of great significance in muscle growth and development. Its principal function lies in suppressing the proliferation and differentiation of skeletal muscle cells, thus controlling muscle mass. In this study, we obtained the genomic sequence of mstn1 from Acanthopagrus latus, which is 2,198 bp in length and encodes 384 amino acids. It consists of three distinct domains: a TGF-β domain, a TGF-β propeptide domain and a signal peptide. Through phylogenetic analysis, it was found that mstn1 and mstn2 from A. latus are closely grouped with those from Sparus aurata, which implies a high level of similarity between the two species. Additionally, mstn1 was mainly expressed in the brain, white muscle, and skin. To further investigate the regulatory mechanisms underlying mstn1 in muscle growth, we analyzed the transcriptional levels of mstn1 in white muscle under conditions of starvation and refeeding. The results indicated that during the 56-day experimental period, the expression of the mstn1 gene decreased notably as the starvation period extended. Truncation experiments revealed that the region from - 645 to + 112 bp constitutes the core promoter region responsive to Mef2a and Mef2b. The point mutation analysis verified that the transcriptional activity of mstn1 is contingent upon the mutation of binding site 3 (M3) regulated by Mef2a and Mef2b. Moreover, siRNA-mediated knockdown experiments demonstrated that downregulation of mef2a or mef2b significantly decreased the transcription of mstn1. These findings provide novel insights into how Mef2 transcription factors regulate mstn1 expression, enhancing our understanding of the molecular mechanisms underlying muscle development in teleost fish.

Totoaba (Totoaba macdonaldi) aquaculture offers economic and ecological advantages. However, its culture still relies on fishmeal in diets because alternative protein sources show reduced productive performance. The current study assessed the impact of low concentrations of methionine and taurine together with alternative proteins, on the productive performance of T. macdonaldi over a 60-day experimental period. Four diets were formulated for this purpose, a basal diet (D-BD), the basal diet with methionine (D-MET), the basal diet with taurine (D-TAU), and the basal diet with methionine and taurine (D-MET + TAU). The present experiment used a randomized design. One hundred forty-four juveniles (41.0 ± 0.5 g in weight) were randomly distributed in 12 tanks (500 L) in triplicate groups to assess biological indices, cholesterol content, hepatic gene expression, and the synthesis and transport of taurine. The statistical analysis revealed that the dietary treatments D-MET and D-TAU positively affected the growth rate, whereas their interaction resulted in a significantly higher growth (p < 0.05). The expression of the igf-1 gene in the liver increased and showed a positive interaction. When TAU and MET were limited, there was an observed overexpression of csad in hepatic tissue. Diets supplemented with TAU showed a decrease in total cholesterol level, whereas cholesterol level in the liver increased with MET supplemented alone. Total TAU content in fish tissues was significantly higher when both TAU and MET were supplemented. In conclusion, T. macdonaldi exhibits a limited capacity, for TAU synthesis, and MET limitation appears to restrict growth potential.

Plastics are ubiquitous in the environment, widely used in diverse industrial applications, yet they pose escalating environmental challenges due to their persistence and bioaccumulative potential as microplastics (MP). Alongside this, the average global temperature increase represents an additional physiological stressor for many species. This study investigated the bioaccumulation and physiological impacts of polystyrene MP (spherical, 1.1 µm) on Odontesthes argentinensis larvae under two distinct temperatures (22 and 26 ºC). Larvae were exposed to MP concentrations of 40 and 400 µg/L for 96 h, with a control group maintained under identical conditions without MP exposure. Our findings revealed MP bioaccumulation in larval tissues, along with significant biochemical effects: reduced superoxide dismutase (SOD) activity, increased catalase (CAT) and glutathione S-transferase (GST) activities, particularly at higher temperatures, as well as elevated lipid peroxidation levels and reduced growth. These results underscore the susceptibility of O. argentinensis larvae to MP exposure and elevated temperatures, reflecting projected climate scenarios that may compromise the species' ecological success and cause socioeconomic harm to communities reliant on fishing.

In response to the mounting pressures of climate change on aquaculture, this study investigates the potential of dietary fulvic acid (FA) supplementation to improve the resilience and growth performance of large yellow croaker (Larimichthys crocea) under conditions of high temperature stress. Conducted from July 14 to September 14, the experiment involved juvenile large yellow croakers acclimatized and then distributed into five treatment groups, with FA incorporated into their diets at concentrations of 0 g/kg, 2 g/kg, 4 g/kg, 8 g/kg, and 16 g/kg. Utilizing a multi-omics approach, we analyzed the impact of FA on the transcriptomic, metabolomic, and microbiomic profiles of the fish, focusing on the liver and gut tissues. The results demonstrated substantial improvements in weight gain and specific growth rates in the FA-supplemented groups, with the highest survival and growth metrics observed at the 0.8% FA concentration. Notably, FA supplementation induced significant enhancements in metabolic pathways critical for stress response, including fatty acid degradation and the PPAR signaling pathway, which are pivotal for managing lipid and glucose metabolism under thermal stress. Additionally, FA was found to beneficially alter the gut microbiota, increasing the abundance of Actinobacteriota, which is associated with reduced inflammation and enhanced intestinal health. The study highlights the efficacy of FA in bolstering the metabolic, physiological, and immunological resilience of large yellow croaker to adverse temperature conditions, thereby providing a viable, non-antibiotic strategy to enhance aquaculture productivity in the face of global warming.

This preliminary study investigates the impact of dietary supplementation with 2 mL/kg of either lemongrass (Cymbopogon citratus) or chamomile (Matricaria chamomilla) essential oils on the welfare of European seabass. To simulate typical operational stress, the fish (520 days post-hatching; 156.48 ± 25.05g) were subjected to a 15-min acute stressor, mimicking offshore sampling for biometric measurements, on days 15 and 33 of the feeding trial. Our results showed that these additives did not cause any signs of disease, toxicity, or mortality. They revealed significant effects of these essential oils (p < 0.05), particularly the lemongrass-enriched diet, on fish appetite and daily feed intake, as well as on growth performance (weight gain per month, specific growth rate, and thermal growth coefficient) and feed utilization (condition factor, feed conversion ratio, and protein efficiency ratio). These parameters progressively improved over the duration of administration (p < 0.001). Positive effects were observed on organosomatic indices, with improvements in the hepatosomatic index and a reduction in the visceral fat index. Furthermore, these oil-enriched diets significantly improved total protein levels and hematocrit percentages (p < 0.001). This increase persisted over time (p < 0.01) and was not affected by stress induced by the sampling operation. Cortisol, lactate, and glucose levels fluctuated depending on the diets and duration of administration, but remained within normal ranges for healthy fish. There was also individual variability among fish within the same feeding group regarding these zootechnical and physiological responses. Finally, the bacterial load of Enterobacteriaceae, Enterococci, and total flora in the intestinal and skin mucus of seabass decreased after one month of feeding with essential-oil-based diets, particularly with chamomile. In conclusion, dietary inclusion of lemongrass and chamomile essential oils appears to offer promising anxiolytic and immunomodulatory benefits. However, further investigations are warranted to confirm their viability as a nutritional strategy to enhance the welfare and resilience of D. labrax in Mediterranean aquaculture.

The black rockfish (Sebastes schlegelii), an important species in aquaculture, has experienced significant population declines due to habitat degradation and overfishing. Despite its rapid growth making it attractive for aquaculture, larval rearing remains challenging, as high-density culture conditions frequently lead to skeletal deformities and slowed growth. To elucidate the molecular mechanisms supporting this fast growth and developmental transitions, we profiled transcriptomic changes across three developmental stages (n = 3 per stage): larval (5 days post-hatching, dph), post-larval (21 dph), and juvenile (45 dph). RNA-Seq generated 56.77 Gb of clean data, resulting in 21,837 annotated unigenes. Differential expression analysis (|log₂FC|≥ 1.2, FDR < 0.05) identified dynamic transcriptomic changes, with 3532 upregulated and 3383 downregulated genes in the 21 vs. 5 dph comparison, and 3789 upregulated and 4582 downregulated genes in the 45 vs. 21 dph comparison. GO enrichment revealed stage-specific pathways, including antigen processing in larvae and autophagy in post-larvae. KEGG pathway analysis underscored notable changes in metabolic processes, including long-term potentiation (21 vs. 5 dph) and proteasome-mediated protein degradation (45 vs. 21 dph). Hub genes, including haao, sec61a1, and vcp, were implicated in energy metabolism, protein synthesis, and cell cycle regulation, supporting rapid growth and tissue differentiation. This study provides fundamental transcriptomic data for exploring early development in S. schlegelii. The identified genes and pathways may facilitate further investigations into growth mechanisms and offer a molecular basis for improving larval survival and aquaculture performance.

The study investigated how varying levels of dietary starch influence the growth, health status, and glucose-lipid metabolism of mandarin fish (initial body weight: 106 ± 1 g). Five diets containing graded levels of digestive starch were formulated (6.56%, 9.03%, 13.03%, 16.46%, and 19.57%), designated as D6.56, D9.03, D13.03, D16.46, and D19.57, respectively. Each diet was administered to triplicate groups of mandarin fish twice daily over 8 weeks. Results showed that growth performance increased linearly, peaking in the D13.03 group starch level before declining (P < 0.05). Liver and muscle lipid content and hepatic glycogen increased significantly in a quadratic and linear manner, respectively (P < 0.05). Transcriptional analysis revealed a starch-dependent upregulation of insulin signaling (ira, pi3kr1, and akt1) and glycolysis (gk, pfkl, and pk) genes, with concurrent downregulation of gluconeogenesis (fbp1 and g6pc) (P < 0.05). Protein expression analysis showed the ratio of p-PI3KR1 to PI3KR1 was significantly elevated as dietary starch increased, with the D13.03 group showing higher ratios than the D19.57 group (P < 0.05). FoxO1 expression was decreased in high-starch groups and reached a peak in the D13.03 group, while the phosphorylation of FoxO1 was significantly elevated (P < 0.05). Additionally, ChREBP and SREBP-1 protein levels were elevated in the D13.03 and D19.57 groups compared to the D6.56 groups (P < 0.05). In conclusion, mandarin fish showed superior carbohydrate tolerance with optimal growth at 13.03% dietary starch, which was partly due to the superior capacity to convert carbohydrates into triglycerides.

Killifish are notable for their remarkable regenerative capabilities, offering valuable insights into vertebrate tissue repair. This review synthesizes current knowledge on fish regeneration, focusing on the emerging model organism killifish Aphaniops hormuzensis (family Aphaniidae), a species capable of regenerating multiple structures-including the caudal fin, kidneys, central nervous system (telencephalon and spinal cord), and integumentary structures (scales). A comparative analysis with established models like zebrafish and medaka underscores the exceptional speed and efficiency of A. hormuzensis regeneration; it achieves complete spinal cord restoration within five days and brain tissue repair within seven days post-injury-significantly faster than zebrafish. The species employs blastema-mediated epimorphic regeneration, mirroring mechanisms in other teleosts but at an accelerated rate. Like many short-lived vertebrates, A. hormuzensis displays age-dependent declines in regenerative capacity, a trait explored in related killifishes. We explore the ecological and evolutionary implications of these traits, synthesizing how killifish models bridge comparative biology and regenerative medicine. The review critically evaluates the potential of killifishes, particularly A. hormuzensis, as powerful models for biomedical research, arguing that their unique regenerative kinetics and life history traits provide novel insights into neuroregeneration, organ repair, and the impact of aging on tissue repair. By highlighting these advances, this work underscores the importance of diversifying model organisms to fully understand the principles of tissue regeneration and their applications for human health.