Fish Physiology and Biochemistry最新文献

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.

Owing to overfishing and habitat degradation, the population of wild seahorses has declined substantially. Aquaculture is recognized as the most efficient approach to reconcile market demands with the conservation of wild seahorse populations. However, the lack of research on basic biology, especially histological studies, has severely hindered the advancement of large-scale seahorse aquaculture. In this study, the organogenesis of the big-belly seahorse (Hippocampus abdominalis), the major farmed seahorse species in China, was analyzed from 1 to 75 days after birth (DAB), which corresponds to 19 to 1,425 day degrees (D°). Three main developmental stages were identified: 1) DAB 1-10 (19-190 D°, early planktonic stage): On the DAB 1 (19 D°), the mouth and anus opened, indicating that they had acquired basic food-selecting ability. On the DAB 10 (190 D°), the first intestinal loop appeared in the intestine to accommodate to intestinal growth and meet increasing nutritional demands. Meanwhile, the female ovary was observed for the first time. 2) DAB 10-30 (190-570 D°, late planktonic stage): This stage was primarily characterized by the maturation of the respiratory and urinary systems. Notably, the brood pouch was first observed on the DAB 15 (285 D°). 3) DAB 30-75 (570-1,425 D°, benthic stage): At DAB 30 (570 D°), the second intestinal loop appeared in the intestine by which time the intestinal tract was basically fully developed. The depth of the ocular fovea increased, which coincided with the transition of seahorses from the planktonic stage to the benthic stage. Throughout the research period (DAB1-75, 19-1,425 D°), the male gonads were not found. This study fills the gaps in the biological and physiological knowledge of this species, as well as provides a theoretical foundation for further insights into the growth and developmental mechanisms of the big-belly seahorse.

Microplastics (MPs), which are tiny particles measuring less than 5 mm, have emerged as a notable environmental issue due to their widespread presence in aquatic environments and their potential to harm aquatic organisms. In this study, the diet of tilapia (Oreochromis niloticus) exposed them to two types of MP materials: PE and PVC fragments. The fish were exposed for three weeks (21 days), and various behavioural changes and mortality were noticed. Moreover, microplastics can impact the growth, reproduction, and survival of tilapia, as evidenced by reduced growth rates and observed behavioural changes in exposed fish. Such modifications might have important effects on the general condition and population dynamics of aquatic environments. In both the gill and gastrointestinal tract (GIT), the MP fragments were accumulated. The GIT of tilapia fish revealed 4.8 ±2.7 items/individual from the collected PVC pieces; gills included 6.6±2.07 items/individual. Similarly, PE fragment accumulation in the GI tract of fish showed 5.6±2.6 items/individual, and the gills showed 5.8±0.84 items/individual. A dietary intake of microplastics led to increasing inflammatory alterations in the liver and intestines. This study assessed the levels of oxidative enzymes in exposed groups of fish (control, PVC, and PE fragments). The MP-exposed tilapia fish exhibited remarkable changes in the enzyme level and the nutritional values, which were compared to control groups. All things considered, microplastics seriously compromise the health and ecological processes of freshwater fish, including tilapia. More study is required to completely understand these effects as well as develop feasible strategies for reducing the microplastics' hazard in freshwater habitats.

A 42-day feeding trial was conducted to determine the effects of different lipid and phospholipid (PL) levels on growth performance, fatty acid composition, fat deposition, antioxidant capacity, and liver health of largemouth bass (Micropterus salmoides) larvae. Six diets were designed: 6% lipids and 0% PLs (L6/PL0), 3% lipids and 3% PLs (L6/PL50), 0% lipids and 6% PLs (L6/PL100), 12% lipids and 0% PLs (L12/PL0), 6% lipids and 6% PLs (L12/PL50), and 0% lipids and 12% PLs (L12/PL100). These correspond to gradient designs for PLs replacing 0%, 50%, and 100% lipids at the 6% and 12% lipids levels. Results showed that dietary PL supplementation significantly enhanced body weight gain (BWG) and specific growth rate (SGR), with the highest BWG in L12/PL100. PL supplementation reduced both the hepatosomatic index (HSI) and viscerosomatic index (VSI), with the L6/PL100 having the lowest levels. The PL supplementation efficiently reduced liver fat deposition and neutral lipid/polar lipid ratio. The n-3 polyunsaturated fatty acid content in the polar lipid fraction was significantly higher than that in the neutral lipid fraction. Dietary PL supplement significantly increased hepatopancreatic catalase and glutathione activities and decreased malondialdehyde content in the hepatopancreas. PL supplementation significantly reduced liver triglyceride and total cholesterol levels, with the lowest levels observed in the L6/PL100 and L12/PL100 groups. These findings demonstrate that graded PL replacement (up to 100%) at the 6% lipid level optimized growth, reduced fat deposition, increased antioxidant capacity, and avoided the metabolic burden induced by high fat (12% lipids), enhancing LB larval health.