Search Results (79)

Eriobotrya japonica (Thunb.) Lindl. leaves are rich in polyphenolic compounds, yet their toxicological effects in aquatic models remain poorly understood. This study evaluated the impact of a hydroethanolic E. japonica leaf extract on zebrafish embryos through the use of morphological, behavioral, and biochemical parameters. The 96 h LC₅₀ was determined as 189.8 ± 4.5 mg/L, classifying the extract as practically non-toxic, according to OECD guidelines. Thereby, embryos were exposed for 90 h to 75 and 150 mg/L concentrations of the E. japonica leaf extract. While no significant effects were noted at the lowest concentration of 150 mg/L, significant developmental effects were observed, including reduced survival, delayed hatching, underdevelopment of the swim bladder, and retention of the yolk sac. These malformations were accompanied by marked behavioral impairments. Biochemical analysis revealed a concentration-dependent increase in superoxide dismutase (SOD) and catalase (CAT) activity, suggesting the activation of antioxidant defenses, despite no significant change in reactive oxygen species (ROS) levels. This indicates a potential compensatory redox response to a pro-oxidant signal. Additionally, the acetylcholinesterase (AChE) activity was significantly reduced at the highest concentration, which may have contributed to the observed neurobehavioral changes. While AChE inhibition is commonly associated with neurotoxicity, it is also a known therapeutic target in neurodegenerative diseases, suggesting concentration-dependent dual effects. In summary, the E. japonica leaf extract induced concentration-dependent developmental and behavioral effects in zebrafish embryos, while activating antioxidant responses without triggering oxidative damage. These findings highlight the extract’s potential bioactivity and underscore the need for further studies to explore its safety and therapeutic relevance. Full article

The gel-forming ability of collagens is vital for their application in cell scaffolds, yet very few comparative studies on fish collagen sources are available. This study isolated and characterized type I collagens from carp skin (CSK), scales (CSC), and swim bladders (CSB) and sturgeon skin (SSK) and swim bladders (SSB). The carp collagens exhibited higher thermal stability (34.75–34.78 °C) and formed more transparent, stronger gels than the sturgeon collagens. Additionally, as demonstrated by scanning electron microscopy, the sturgeon collagens exhibited faster fibril formation, with visible fibrils after 3 h which grew thicker but did not form bundles. The carp collagens, in contrast, initially displayed fewer, thinner, and longer fibrils, with their formation accelerating over time and fibril bundles emerging after 24 h. All collagen solutions of 4% (w/v) exhibited shear-thinning flow behavior, with the carp-derived solutions showing higher viscosities (10³–10⁴ Pa·s) than those demonstrated by the sturgeon-derived solutions (10²–10³ Pa·s). The CSBs and SSBs demonstrated the highest storage (G′) and loss (G″) moduli, with the former exhibiting the lowest loss tangent (tan δ), indicative of a stronger gel structure. The gels at 24 h showed slightly poorer mechanical properties than those at 3 h. The CSC and SSB gels had the highest thermal stability. These findings highlight the distinctiveness of the characteristics of collagens and their gels, emphasizing their potential in biomaterial applications. The present study also provides a foundational framework for assessing cellular responses in a comparative context that may help in identifying the most suitable collagen types for biomedical applications. Full article

This study explores the identification, characterization, and biological evaluation of angiotensin I-converting enzyme (ACE)-inhibitory peptides derived from enzymatic hydrolysates of crucian carp swim bladders. Following sequential purification by size-exclusion and reversed-phase chromatography, two bioactive peptides—Hyp-Gly-Ala-Arg (Hyp-GAR) and Gly-Ala-Hyp-Gly-Ala-Arg (GA-Hyp-GAR)—were identified using ultra-high-performance liquid chromatography coupled with linear ion trap–Orbitrap tandem mass spectrometry. The synthetic peptides demonstrated potent ACE-inhibitory activity in vitro, with IC₅₀ values of 12.2 μM (Hyp-GAR) and 4.00 μM (GA-Hyp-GAR). Molecular docking and enzyme kinetics confirmed competitive inhibition through key interactions with ACE active site residues and zinc coordination. In vivo antihypertensive activity was evaluated in spontaneously hypertensive rats, revealing that GA-Hyp-GAR significantly reduced systolic blood pressure in a dose-dependent manner. At a dose of 36 mg/kg, GA-Hyp-GAR reduced systolic blood pressure by 60 mmHg—an effect comparable in magnitude and timing to that of captopril. Mechanistically, GA-Hyp-GAR modulated levels of angiotensin II, bradykinin, endothelial nitric oxide synthase, and nitric oxide. A 90-day subchronic oral toxicity study in mice indicated no significant hematological, biochemical, or histopathological alterations, supporting the peptide’s safety profile. These findings suggest that GA-Hyp-GAR is a promising natural ACE inhibitor with potential application in functional foods or as a nutraceutical for hypertension management. Full article

The Lima River in northern Portugal serves as a vital habitat for diadromous fish species, yet it remains one of the least studied aquatic systems in the region. This study investigates the ecology and biology of key diadromous fish populations, including sea lamprey (Petromyzon marinus), shads (Alosa alosa and Alosa fallax), trout (Salmo trutta), and European eel (Anguilla anguilla), during their reproductive migration and riverine periods. A total of 3242 individuals from 15 species were sampled, with native species accounting for 51.1% of the catch. Results revealed significant differences in size and weight of lampreys, with individuals from the Lima River being significantly smaller than those from regional rivers such as the Minho and Mondego. Shad populations showed a high proportion of hybrids (33.8%), suggesting extensive hybridization between A. alosa and A. fallax. Analysis of trout stomach contents revealed a diverse diet dominated by insects (66.9%), crustaceans (6.8%), and fish (6.8%), but also an alarming presence of plastic debris (1.1%), highlighting potential pollution problems. For European eels, this study marks the first record of the invasive swim bladder parasite Anguillicola crassus in the Lima River, with 84.8% of eels sampled showing moderate to severe swim bladder damage. These findings contribute to a deeper understanding of diadromous fish ecology and emphasize the importance of conservation efforts in estuarine systems worldwide. Full article

The swim bladder of Chu’s croaker (Nibea coibor) is an expensive food with high texture requirements. In this study, we found that male swim bladder had better toughness than female. To explore the main determining factor affecting texture properties of swim bladder, a comparison of proximate composition, collagen microstructure, and proteomics was carried out between male and female swim bladders. Results indicated that it should be collagen microstructure mainly affecting the texture characteristics of swim bladder, rather than the composition. The collagen fibers in male swim bladder were significantly more uniform and regular than female. By proteomics analysis, it was further discovered that collagen XII was the most significantly up-regulated protein in the male swim bladder and may be crucial in morphology of collagen fibers. In summary, collagen XII was identified to be a potential key molecule affecting the texture of the swim bladder, mainly through regulating properties of collagen fibers. This study contributes to a deeper understanding of the structural characteristics of swim bladder collagen and provides critical molecular targets for the regulation of texture in swim bladder. Full article

The threadsail filefish, Stephanolepis cirrhifer, is an economically important marine species. However, wild catches have sharply decreased over the past 20 years, causing S. cirrhifer to be added to the IUCN Red List of Threatened Species. Accordingly, this study seeks to promote technological development for artificial breeding and early life-stage farming by defining the morphological characteristics of ontogenesis. The fertilized eggs, with a diameter of 0.62 ± 0.01 mm, were spherical and sticky and contained multiple oil globules of varying sizes. The embryonic development was observed and divided into eight phases, which were cleavage, blastocyst, gastrula, neurula, organogenesis, muscular contraction, heart pulsation, and hatching. At 3 days post-hatching (dph), the yolk sac was completely absorbed. The eye developed rapidly, and the mouth fissure and anus initially formed. Some larvae were fed on S-rotifers (Brachionus plicatilis). At 6–8 dph, the upper and lower jaws of larvae were gradually covered by leathery skin, and the head-to-body proportion increased. At 14–16 dph, the fin differentiation occurred in the dorsal, anal, and pectoral fins, with widespread distribution of yellow and melanin on the body surface. Swim bladder was clear. The swimming ability of larva was enhanced, resulting in an obvious clustering phenomenon. At 22–25 dph, the end of the notochord continued to tilt upwards, forming a tail fin. The trunk was evenly distributed with protruding circular punctate scales. The snout was covered with leathery epidermis, and the mouth began to round. At 40–45 dph, the juvenile completed metamorphosis, with horizontal dark stripes appearing on the trunk. Pigmented spots appeared on the tail fins. The counts of dorsal and anal fin spines were 34–36 and 32–34 dph, respectively. During the development of larvae and juveniles, the growth parameters, such as total length, standard length, body height, and body weight, were made as growth curves. The slopes of growth curves were calculated. We found two inflexion points occurring in the growth curves, which may be associated with metamorphosis and transitions in feeding habits. These results enrich the biological understanding of filefish species while providing guidance for artificial propagation and fry production in S. cirrhifer. Full article

Grass carp swim bladder collagen peptides (GCPs) were purified by ultrafiltration and Sephadex G-15 chromatography to obtain GCP-II, which exhibited superior antioxidant activity. GCP-II exhibited 78.22% ABTS⁺ scavenging activity and 72.91% Fe²⁺ chelating activity, along with around 90% thermal stability between 4 °C and 100 °C. Environmental factors such as 4% NaCl reduced superoxide scavenging to 59.16% of the original and 0.2% citric acid reduced it to 71.57% of the original, while glucose showed minimal impact on the antioxidant activity of GCP-II. From 464 GCP-II sequences analyzed via LC-MS/MS, 7 bioactive peptides were selected based on antioxidant activity and functional sequence motifs, and were named peptides 1 to 7, respectively. These peptides were synthesized through solid-phase methods, validated for purity exceeding 95% using HPLC and mass spectrometry, and tested for antioxidant performance. Peptides 1, 3, 6, and 7 demonstrated notable antioxidant efficacy: peptide 6 showed 63.31% ABTS⁺ scavenging activity at 1 mg/mL, while peptides 3 and 6 exhibited synergistic effects in DPPH and hydroxyl radical scavenging experiments, surpassing theoretical values by 0.88% and 2.16%, respectively. This study underscores the potential of synthetic GCPs and GCP-II-derived peptides as functional antioxidants, particularly peptide 3 and peptide 6. Full article

Emerging contaminants refer to chemical substances that have not been widely regulated but possess the potential to cause adverse effects on both the environment and human health. Antibiotics, as emerging contaminants, pose significant threats to ecosystems and human health due to their widespread use and persistence in the environment. Levofloxacin, a broad-spectrum fluoroquinolone antibiotic, is commonly employed in the treatment of bacterial infections, and has been frequently detected in environmental matrices and freshwater systems. In this study, we assessed the effects of levofloxacin on hatchability, mortality rates, malformations, behavioral changes, and cardiac development in zebrafish embryos by exposing them to varying concentrations of levofloxacin (0, 0.5, 1, 2, 4, and 8 mM). Our results demonstrate that levofloxacin exposure significantly impaired the growth and development of zebrafish larvae, particularly at higher concentrations. Notable effects included reduced body length, abnormal yolk sac and swim bladder development, pericardial edema, prolonged distances between the sinus venosus and arteriolar bulb (SV-BA), and disruptions in heart rate. Quantitative PCR analysis further revealed that levofloxacin exposure significantly upregulated the expression of key cardiac development genes in zebrafish larvae, including nppa, myh6, cacna1ab, myl7, gata4, nkx2.5, tbx2b, and tbx5b. These findings indicate that levofloxacin exposure exerts significant toxic effects on both embryonic and larval growth as well as heart development and gene expression in zebrafish. This study provides critical insights into the potential ecological risks posed by levofloxacin along with other antibiotics while laying a foundation for further investigation into their toxicological mechanisms. Full article

In this work, the hypolipidemic and antioxidative capacity of FSGLR (S7) and GIEWA (S10) from miiuy croaker swim bladders was explored systematically in an oleic acid (OA)-induced nonalcoholic fatty liver disease (NAFLD) model of HepG2 cells. Moreover, the hypolipidemic activity of S7 and S10 and their antioxidative abilities were preliminarily investigated in combination with molecular docking technology. The results indicated that S7 and S10 could decrease the amount of lipid accumulation and the content of triglycerides (TG) and total cholesterol (TC) in the OA-induced NAFLD cell model in a dose-dependent manner. In addition, S7 and S10 exhibited better bile salt binding, pancreatic lipase (PL) inhibition, and cholesterol esterase (CE) inhibition capacities. The hypolipidemic mechanisms of S7 and S10 were connected with the downregulation of the mRNA expression levels of adipogenic factors, including sterol-regulatory element-binding protein-1c (SREBP-1c), acetyl-CoA carboxylase (ACC), sterol-regulatory element-binding protein (SREBP)-2, hydroxymethylglutaryl-CoA reductase (HMGR), and fatty acid synthase (FAS) (p < 0.01), and the upregulation of the mRNA expression of β-oxidation-related factors, including carnitine palmitoyltransferase 1 (CPT-1), acyl-CoA oxidase 1 (ACOX-1), and peroxisome proliferator-activated receptor α (PPARα). Moreover, FSGLR (S7) and GIEWA (S10) could significantly protect HepG2 cells against OA-induced oxidative damage, and their antioxidant mechanisms were related to the increased activity of intracellular antioxidant proteases (superoxide dismutase, SOD; glutathione peroxidase, GSH-PX; catalase, CAT) to remove excess reactive oxygen species (ROS) and decrease the production of malondialdehyde (MDA). The presented findings indicate that the hypolipidemic and antioxidant functions and mechanisms of S7 and S10 could make them potential hypolipidemic and antioxidant candidates for the treatment of NAFLD. Full article

Salmonids, classified as physostomous fish, maintain buoyancy by ingesting air to inflate their swim bladders. Long-term submergence has been shown to cause body imbalance and reduced growth performance in these fish. Previous studies have demonstrated that extended photoperiod can promote growth in salmonids. This study aimed to investigate the regulatory effects of prolonged lighting on the growth of submerged rainbow trout (Oncorhynchus mykiss) by examining the transcriptional expression of genes in the growth hormone (GH)-insulin-like growth factor (IGF) axis. Rainbow trout were individually reared in one of the six environments, defined by the combination of three photoperiods (0L:24D, 12L:12D, and 24L:0D) and two spatial rearing modes (routine and submerged), for 16 weeks. We compared the growth performance of rainbow trout in different environments and further analyzed the transcription profiles and correlations of GH-IGF axis genes in the brain, liver, and muscle. The findings of this study were as follows: growth performance of rainbow trout gradually increased with photoperiod duration. Specifically, final body weight (FBW) and specific growth rate (SGR) increased, while feed conversion ratio (FCR) decreased. Extended photoperiod partially mitigated the adverse effects of long-term submergence on rainbow trout growth. Under 24L:0D photoperiod conditions, growth performance (FBW, SGR, and FCR) in submerged and routine rainbow trout was more closely aligned compared to 0L:24D and 12L:12D photoperiod conditions. In response to variations in the photoperiod, GH-IGF axis genes of rainbow trout exhibited significant transcriptional differences, particularly between treatments with 0L:24D and 24L:0D light exposure. An extended photoperiod facilitated the restoration of the expression of GH-IGF axis genes in submerged rainbow trout towards routine levels, including the up-regulation of sst and sstr2 genes in the brain. Correlation analysis implied differentiation of physiological functions of ghr and igfbp paralogs. This study provided insights into the feasibility of enhancing the growth performance of submerged salmonids through photoperiod manipulation. Full article

Despite the close and clinically confirmed association between depression and overactive bladder, it remains unclear whether this affective disorder is a factor causing overactive bladder or whether overactive bladder is a specific symptom of psychosomatic disorders. This study examined the effects of repeated corticosterone administration on the occurrence of symptoms associated with depression and overactive bladder. Additionally, we examined whether administering TC-G 1008, an antidepressant that selectively activates the GPR39 receptor, could alleviate corticosterone-induced depression-like behavior and detrusor overactivity-related changes in cystometric measurements. We also explored its potential to reverse alterations in various biomarkers associated with both conditions in the serum, urinary bladder, and brain of female rats. The administration of corticosterone (20 mg/kg/day for 14 days) yielded anticipated results, including an increase in the duration of immobility during the forced swim test, alterations in parameters specific to bladder overactivity, a decrease in neurotrophins, and an elevation in pro-inflammatory cytokine levels. Treatment with TC-G 1008 (15 mg/kg/day) alleviated symptoms of both detrusor overactivity and depression, while also restoring the levels of biochemical and cystometric markers to normal ranges. Additionally, antidepressants based on GPR39 agonists could enhance the levels of kynurenic acid in the neuroprotective pathway. These results indicate that the GPR39 agonist receptor might be a promising future therapeutic approach for treating overactive bladder that occurs alongside depression. Full article

As a highly sensitive vibrational technique, Raman spectroscopy (RS) can provide valuable chemical and molecular data useful to characterise animal cell types, tissues and organs. As a label-free, rapid detection method, RS has been considered a valuable asset in forensics, biology and medicine. The technique has been applied to zebrafish for various purposes, including physiological, biochemical or bioaccumulation analyses. The available data point out its potential for the early diagnosis of detrimental effects elicited by toxicant exposure. Nevertheless, no baseline spectra are available for zebrafish embryos and larvae that could allow for suitable planning of toxicological assessments, comparison with toxicant-elicited spectra or mechanistic understanding of biochemical and physiological responses to the exposures. With this in mind, this work carried out a baseline characterisation of Raman spectra of zebrafish embryos and larvae throughout early development. Raman spectra were recorded from the iris, forebrain, melanocytes, heart, muscle and swim bladder between 24 and 168 h post-fertilisation. A chemometrics approach, based on partial least-squares discriminant analysis (PLS-DA), was used to obtain a Raman characterisation of each tissue or organ. In total, 117 Raman bands were identified, of which 24 were well represented and, thus, retained in the data analysed. Only three bands were found to be common to all organs and tissues. The PLS-DA provided a tentative Raman spectral fingerprint typical of each tissue or organ, reflecting the ongoing developmental dynamics. The bands showed frequencies previously assigned to collagen, cholesterol, various essential amino acids, carbohydrates and nucleic acids. Full article

Iprodione (IDN) is a broad-spectrum fungicide used to treat various fungal infections in plants. Despite its extensive use, assessment of its toxicity in aquatic organisms remains incomplete. This study investigated the deleterious effects of IDN using zebrafish (ZF) as a model organism. ZF embryos, beginning at 2 h post-fertilization (hpf), were exposed to IDN (3.75–40 mg/L), and both mortality and deformities were assessed. The impact of IDN on mortality was concentration-dependent and significant from 14 mg/L. Importantly, IDN induced several deformities at sublethal concentrations, including abnormal somites, reduced retinal pigment accumulation, yolk sac edema, hatching failure, abnormal swim bladders, and spinal curvature. The EC₅₀ values for IDN-induced deformities were 3.44 ± 0.74 to 21.42 ± 6.00 mg/L. The calculated teratogenic index values for all deformities were above 1, indicating that IDN is teratogenic to ZF. IDN-exposed ZF also displayed abnormalities in touch-evoked escape responses. IDN significantly affected heart rate and blood flow, and induced pericardial edema and hyperemia in a concentration-dependent manner, suggesting its influence on cardiac development and the function of ZF. In conclusion, these results suggest that IDN exerts toxic effects on ZF embryos, affecting mortality, development, and behavior. Full article

Fish swim bladder (FSB) is a type of traditional nutraceutical, but the lack of high-quality drying methods limits its premium market development. In order to obtain optimal-quality dried FSBs from Chinese longsnout catfish, the effects of liquid nitrogen pre-freezing (LNF) and drying on the physical properties and flavor of FSB were evaluated. Four methods were used for FSB drying, including natural air-drying (ND), hot-air-drying (HD), LNF combined with freeze-drying (LN-FD), and LNF combined with HD (LN-HD). Color, collagen content, rehydration ratio, textural properties, and flavor characteristics (by GC-IMS, E-nose, and E-tongue) were measured to clarify the differences among four dried FSBs. The results showed that ND cannot effectively remove moisture from FSB as the final product showed a stronger sourness in taste. HD led to a decrease in the collagen content and the collapse of the fiber structure in FSB. Compared to HD, LN-HD showed a higher collagen content (0.56 g/g) and a different flavor fingerprint. FSB treated by LN-FD had better physical qualities in terms of an attractive color, a high collagen content (0.79 g/g), low shrinkage, a higher rehydration ratio (2.85), and a soft texture, while also possessing richer characteristic flavors. The application of LN-FD may help the optimization of the nutrition level, rehydration ability, mouthfeel, and flavor of dried FSB. Full article

With the growing dependence on lithium-ion batteries, there is an urgent need to understand the potential developmental toxicity of LiPF₆, a key component of these batteries. Although lithium’s toxicity is well-established, the biological toxicity of LiPF₆ has been minimally explored. This study leverages the zebrafish model to investigate the developmental impact of LiPF₆ exposure. We observed morphological abnormalities, reduced spontaneous movement, and decreased hatching and swim bladder inflation rates in zebrafish embryos, effects that intensified with higher LiPF₆ concentrations. Whole-mount in situ hybridization demonstrated that the specific expression of the swim bladder outer mesothelium marker anxa5b was suppressed in the swim bladder region under LiPF₆ exposure. Transcriptomic analysis disclosed an upregulation of apoptosis-related gene sets. Acridine orange staining further supported significant induction of apoptosis. These findings underscore the environmental and health risks of LiPF₆ exposure and highlight the necessity for improved waste management strategies for lithium-ion batteries. Full article