Search Results (15)

This study systematically deciphers a comprehensive analysis of biochemical and sensory variations in Takifugu obscurus, evaluating the seasonal dynamics, salinity gradients (0 and 3‰), and nutritional regimes on quality determinants in aquaculture. To the best of our knowledge, the mechanistic links between cultivation factors and organoleptic quality were first established through integrative biochemical profiling, including proximate composition, free amino acids, taste-active nucleotides, and mineral ions, coupled with quantitative sensory evaluation. The results revealed that spring samples exhibit 44.7% higher inosine monophosphate than that of autumn and 92.8% elevated ATP, correlating with superior umami-kokumi attributes. Salinity adaptation drove metabolic trade-offs: freshwater cultivation amplified flavor-enhancing amino acids, while brackish systems prioritized ionic precision. Short-term fasting induced alanine accumulation without sensory compromise, demonstrating nutritional plasticity. Polyculture compatibility was evidenced by negligible quality divergence from monoculture, despite enhanced productivity. These insights advance sustainable aquaculture through science-driven strategies that harmonize ecological resilience, economic viability, and culinary excellence in commercial Takifugu obscurus production. Full article

Helicobacter pylori (H. pylori) infection is a widespread gastric infectious disease, posing significant challenges due to the increasing prevalence of antibiotic resistance. This study aimed to evaluate the synergistic antibacterial activity of Takifugu obscurus skin peptides (TSPs) and the cell-free supernatant of Lactobacillus plantarum WUH3 (LCFS) in developing a potential green and efficient dietary supplement therapy. Using enzymatic hydrolysis and ultrafiltration techniques, the most bioactive peptide fraction, TSPb (1–3 kDa), was identified. The effects of TSPb and LCFS—both individually and in combination—on H. pylori biofilm function, membrane morphology, and internal structure were systematically analyzed using urease activity, N-phenyl naphthylamine (NPN) uptake, nucleic acid leakage, scanning electron microscopy (SEM), and infrared (IR) spectroscopy. The results showed that both LCFS and TSPb significantly inhibited H. pylori urease activity, with inhibition rates of 53.60% and 54.21% at 24 h, respectively, and the highest inhibition rate of 74.64% was observed with their combined treatment. SEM, NPN fluorescence, and nucleic acid leakage analyses revealed distinct mechanisms of action for each treatment. LCFS treatment caused membrane surface loosening and morphological deformation, while TSPb induced the formation of localized membrane pores. IR spectroscopy further confirmed that the combined treatment led to a more severe disruption of the lipid and protein structure within the bacterium. Overall, compared to individual treatments, the combination of TSPb and LCFS exhibited enhanced intracellular penetration and a more significant effect on bacterial viability. This study successfully identified TSPb as a highly bioactive peptide and elucidated its potential synergistic antibacterial mechanism with LCFS. These findings provide scientific evidence for the development of functional antimicrobial foods and gastric health dietary supplements, offering a promising strategy for the prevention and management of H. pylori infections. Full article

In October 2023, a disease outbreak in pufferfish (Takifugu obscurus) farms in Zhongshan City, Guangdong, China, caused high mortality. Diseased fish (mean length: 15 ± 1 cm) exhibited swimming disorders, fin rot, hemorrhage, and an enlarged spleen. Histopathological observations generally revealed inflammation, necrosis, and congestion in the spleen, kidneys, and brain tissues. The most severe pathological changes included interstitial edema and tubular atrophy in the kidneys, hemosiderin deposition in the spleen, massive red blood cell infiltration, and a decrease in lymphocytes. A single strain of bacteria (Tol-1) was isolated from the diseased pufferfish and identified as a Gram-positive streptococcus strain, exhibiting α-hemolysis on sheep blood agar plates. Through biochemical characterization, 16S rDNA sequencing, morphological analysis, and specific primer-based identification, the Tol-1 strain was identified as Lactococcus garvieae, serotype I. Antimicrobial susceptibility testing indicated that Tol-1 was sensitive to Chloramphenicol, Ampicillin, Cephalexin, and Doxycycline, but resistant to Kanamycin, Gentamicin and Ciprofloxacin. In addition, 15 common virulence factors were detected in the Tol-1 strain, including adhPav, adhPsaA, adhC I–II, adh, and hly 1–3. Pufferfish (mean length: 17 ± 1 cm) subjected to artificial infection via intraperitoneal injection (IP) with the Tol-1 strain exhibited clinical symptoms and histopathological damage similar to those observed in naturally infected fish. An infection dose of 1 × 10⁵ CFU/fish resulted in 80% mortality. The study fulfilled Koch’s postulates, indicating that the disease outbreak in pufferfish was caused by L. garvieae, which exhibited a high mortality rate in pufferfish despite the subtle clinical symptoms. These results serve as a warning for pufferfish farming areas and provide a scientific basis for future prevention and control efforts. Full article

The obscure puffer (Takifugu obscurus) is a popular cultured species and accounts for around 50% of the total pufferfish production in China. A hybrid puffer was generated by crossing a female obscure puffer with a male tiger puffer (T. rubripes). Its growth model has not been developed and the genetic basis underlying its growth superiority has not yet been fully investigated. In this study, the growth model and morphological traits of the hybrid puffer were explored. The results indicated that the hybrid puffer exhibited a significant growth advantage compared to the obscure puffer. There were also significant differences in their morphological traits. We conducted genotyping-by-sequencing (GBS) on hybrid and obscure puffer groups, identifying 215,288 high-quality single nucleotide polymorphisms (SNPs) on 22 chromosomes. Subsequently, a total of 13 growth-related selection regions were identified via a combination of selection signatures and a genome-wide association study (GWAS); these regions were mainly located on chromosomes 10 and 22. Ultimately, the screened regions contained 13 growth-related genes, including itgav, ighv3-43, ighm, atp6v1b2, pld1, xmrk, inhba, dsp, dsg2, and dsc2, which regulate growth through a variety of pathways. Taken together, the growth models and candidate genes used in this study will aid our understanding of production characteristics and the genetic basis of growth rates. The hybrid will also be of great significance for the genome-assisted breeding of pufferfish in the future. Full article

Nanoparticles of zinc oxide (ZnO NPs) are extensively used in various applications, and their widespread use leads to their environmental presence, particularly in wastewater treatment plant effluents, rivers, and soil. This study focuses on the obscure puffer, Takifugu obscurus, an economically important fish in China, aiming to assess the toxic effects of ZnO NPs on its early life stages, emphasizing the need for understanding the ecological implications of ZnO NP exposure in aquatic environments. Exposure during the hatching stage resulted in a significant decrease in hatching rates, with embryos displaying surface coating at higher ZnO NP concentrations. Newly hatched larvae experienced deformities, and post-hatching exposure led to pronounced reductions in survival rates, particularly with higher ZnO NP concentrations. Two-month-old juveniles exposed to increasing ZnO NP concentrations exhibited a consistent decline in survival rates, emphasizing concentration-dependent adverse effects. Biochemical analyses revealed elevated malondialdehyde (MDA) levels and decreased glutathione (GSH), superoxide dismutase (SOD), and catalase (CAT) activities in various tissues, indicating oxidative stress. This study underscores the ecological risks of ZnO NP contamination in aquatic environments, emphasizing the need for careful consideration of nanoparticle exposure in aquatic ecosystems. Full article

Takifugu obscurus has relatively small gills and gill pores, leading to a relatively low respiratory capacity and increased vulnerability to low dissolved oxygen (DO) levels compared to other fish. To investigate the responses of T. obscurus to acute hypoxic stress, high-throughput-sequencing-based transcriptomic analyses were conducted here to assess the responses of T. obscurus gills to acute hypoxic stress. Three environmental conditions were compared including normoxia (DO: 7.0 ± 0.2 mg/L), hypoxic stress (DO: 0.9 ± 0.2 mg/L), and reoxygenation (4, 8, 12, and 24 h after return to normoxia) conditions to identify differentially expressed genes (DEGs) responsive to hypoxia. A total of 992, 877, 1561, 1412, and 679 DEGs were identified in the normoxia and reoxygenation for 4, 8, 12, and 24 h groups in comparison to the hypoxia groups, respectively. The DEGs were primarily associated with oxidative stress, growth and development, and immune responses. Further functional annotation enrichment analysis of the DEGs revealed that they were primarily related to cytokine–cytokine interactions, transforming growth factor β receptor (TGF-β), cell adhesion molecules (CAMs), the vascular endothelial growth factor (VEGF) signaling pathway, and the mitogen-activated protein kinase (MAPK) signaling pathway. These results provide new insights into the physiological and biochemical mechanisms of T. obscurus adaptations to hypoxic stress. Furthermore, these results provide a framework for future studies into the molecular mechanisms of hypoxia tolerance and the healthy culture of T. obscurus and other fish. Full article

The physicochemical properties of semi-dried Takifugu obscurus fillets in cold air drying (CAD), hot air drying (HAD), and cold and hot air combined drying (CHACD) were analyzed based on pH, water state, lipid oxidation, protein degradation, and microstructure, using a texture analyzer, low-field nuclear magnetic resonance, thiobarbituric acid, frozen sections, sodium dodecyl sulfate polyacrylamide gel electrophoresis, and differential scanning calorimetry. Water binding to the samples was enhanced by all three drying methods, and the immobilized water content of CHACD was between that of HAD and CAD. The pH of the semi-dried fillets was improved by CHACD. When compared to HAD and CAD, CHACD improved the springiness and chewiness of the fillets, especially cold air drying for 90 min (CAD-90), with values of 0.97 and 59.79 g, respectively. The muscle fibers were arranged compactly and clearly in CAD-90, having higher muscle toughness. CHACD reduced the drying time and degree of lipid oxidation compared to HAD and CAD. CAD better preserved protein composition, whereas HAD and CHACD promoted actin production; CHACD had a higher protein denaturation temperature (74.08–74.57 °C). CHACD results in better physicochemical properties than HAD or CAD, including shortened drying time, reduced lipid oxidation, enhanced protein stability, and denser tissue structure. These results provide a theoretical basis for selecting the appropriate drying method for T. obscurus in industrial applications. Full article

ZnO nanoparticles (ZnO NPs) have been applied in a wide range of fields due to their unique properties. However, their ecotoxicological threats are reorganized after being discharged. Their toxic effect on anadromous fish could be complicated due to the salinity fluctuations during migration between freshwater and brackish water. In this study, the combined impact of ZnO NPs and salinity on the early development of a typical anadromous fish, obscure puffer (Takifugu obscurus), was evaluated by (i) observation of the nanoparticle characterization in salt solution; (ii) quantification of the toxicity to embryos, newly hatched larvae, and larvae; and (iii) toxicological analysis using biomarkers. It is indicated that with increased salinity level in brackish water (10 ppt), the toxicity of ZnO NPs decreased due to reduced dissolved Zn²⁺ content, leading to higher hatch rate of embryos and survival rate of larvae than in freshwater (0 ppt). The irregular antioxidant enzyme activity changes are attributed to the toxic effects of nanoparticles on CAT (catalase), but further determination is required. The results of present study have the significance to guide the wildlife conservation of Takifugu obscurus population. Full article

Acid-solubilized (ASC) and pepsin-solubilized collagen (PSC) extracted at 4 °C (ASC-4 and PSC-4), 12 °C (ASC-12 and PSC-12), and 20 °C (ASC-20 and PSC-20) from the skin of farmed pufferfish (Takifugu obscurus) was characterized by SDS-polyacrylamide gel electrophoresis (SDS-PAGE), Fourier-transform infrared spectroscopy (FTIR), and fibril-forming tests. The results indicate that extraction at 12 °C can effectively improve the extraction efficiency of natural collagen compared with extraction at 4 °C. However, extraction at 20 °C results in a decrease in molecular integrity, thus, inducing the resultant collagen to degrade or even lose fibril-forming ability. Transmission electron microscope (TEM) images revealed that ASC-4, PSC-4, ASC-12, and PSC-12 can assemble into fibrils with D-periodicities, and ASC-20 associated into molecular aggregates alongside partial D-banded fibrils, while no well-defined fibrils were observed in PSC-20. Scanning electron microscope (SEM) analysis confirmed the well-defined fibril morphologies of ASC-4, PSC-4, ASC-12, and PSC-12 with imino acid contents between 190.0 and 197.8 residues/1000 residues. The denaturation temperature of ASC-4, PSC-4, ASC-12 and PSC-12 was 30.0, 27.6, 25.9 and 22.7 °C, respectively. This study indicates that ASC and PSC extracted at 4 °C and 12 °C could be alternatives to terrestrial collagens for industrial applications. Full article

Strontium marking technology is commonly used for extensive marking in stock enhancement and releasing activities. In order to explore the feasibility of this technology for juvenile Takifugu obscurus, five different concentrations of strontium (0, 12, 18, 36, and 72 mg/L) were set up by strontium chloride hexahydrate (SrCl₂·6H₂O) and T. obscurus were immersed for 7 days. Then, T. obscurus were reared in non-additive water for 25 days. The results showed that the survival rate of all groups was 100%, except the 72 mg/L group, after 7 days of immersion. Moreover, the growths of all the marked groups were better than that of the control group. There was no significant difference between the control and marked groups, except for the 18 mg/L group, indicating that the appropriate concentration of strontium might have positive effect for T. obscurus. The strontium to calcium (Sr/Ca) ratios of otoliths in the marked groups increased with increasing concentration and time, which were higher than the baseline, respectively. Then, the Sr/Ca ratios returned to the original level, but the peak value was still retained, suggesting that the success rate of the strontium marking reached 100%. Notably, the residual strontium content of 18 mg/L group was insufficient for causing negative effects for T. obscurus after 25 days. Therefore, in consideration of the growth, survival, and effect of strontium marking on otolith, 18 mg/L is an appropriate concentration for strontium marking of juvenile T. obscurus. This study confirmed the feasibility of strontium marking for T. obscurus and provided a new approach to rationally and scientifically evaluate the stock enhancement and releasing efficiency of T. obscurus. Full article

Takifugu obscurus has relatively small gills and gill pores. Consequently, a relatively low respiratory capacity. This fish is thus easily negatively affected by the low levels of dissolved oxygen (DO) that are common in high-intensity aquaculture. In order to clarify the mechanisms underlying the hypoxia response of T. obscurus, we used liquid mass spectrometry (LC–MS) to identify and quantify the metabolites present in the T. obscurus gill under the following conditions: normoxia (DO, 7.0 ± 0.2 mg/L), hypoxia (DO, 0.9 ± 0.2 mg/L), and reoxygenation (4, 12, and 24 h after return to normoxia conditions). We identified a total of 821 and 383 metabolites in the gill in positive and negative ion modes, respectively. Of the metabolites identified in positive ion mode, 136 were differentially abundant between hypoxia and all other conditions; of the metabolites identified in negative ion mode, 34 were differentially abundant between hypoxia and all other conditions. The metabolites which were differentially abundant under hypoxia primarily included glycerol phospholipids, fatty acids, hormones, and amino acids as well as related compounds. The pathways which were significantly enriched in the differentially abundant metabolites included the lipid metabolism, amino acid metabolism, purine metabolism, FoxO signaling pathway, and mTOR signaling pathway. Our results help to clarify the mechanisms underlying hypoxia tolerance and to identify hypoxia-related metabolites, as well as to highlight potential research targets for the development of hypoxic-tolerant strains in the future. Full article

Pufferfish is nutritious and delicious, but the tetrodotoxin (TTX) that may exist in its body poses a serious safety hazard. It is important to use scientific and effective methods to detect the TTX in pufferfish, but most of the existing methods require complex pre-treatment steps and have sample lethality. The solid-phase microextraction (SPME) technology can be used for in vivo detection due to its advantages such as no solvent demand, simple operation, and fast detection speed. In this study, the GO-PAN@PNE SPME fibers were made via a dipping method, and their extraction effect was verified in the TTX aqueous and spiked fish. The established method has good reproducibility, and the limit of detection of TTX in pufferfish was 32 ng·g⁻¹, and the limit of quantitation was 150 ng·g⁻¹, which can meet the detection needs of pufferfish for safe consumption. This method was used to in vivo detect the Takifugu obscurus exposed to the TTX, to determine the content of TTX in the pufferfish muscle. The detection method established in this study can relatively quickly and easily realize the in vivo detection of TTX in the pufferfish, which can provide theoretical support for improvement in the food safety level of the pufferfish. Full article

To investigate pufferfish accumulation, elimination, and distribution of tetrodotoxin (TTX), Takifugu obscurus was fed with wild TTX-containing gastropod Nassarius semiplicata to simulate the natural food chain. Three-month-old non-poisonous T. obscurus was fed with wild toxic N. semiplicata at three exposure dose for 28 days, and later, with toxin-free food until day 67. Three fish individuals from each treatment were sampled, and the distribution of TTX in different tissues was measured. The results showed that the accumulation ratio of TTX in the three exposure dose groups ranged from 35.76% to 40.20%. The accumulation ratio in the skin and liver was the highest amongst all tissues, accounting for more than 85% of the total TTX, whereas that in the kidney and gallbladder was the lowest (0.11–0.78%). Studies on the kinetic of TTX accumulation and elimination revealed that the skin was the tissue with the highest accumulation speed constant (8.06), while the liver, kidney, and intestinal tract showed the highest speed of TTX elimination. The time required for TTX reduction to reach the safety limit could be predicted by using standard elimination equations. Qualitative analysis by UPLC-MS/MS revealed the occurrence of seven TTX derivatives in T. obscurus; of these TTX, 5-deoxy TTX, 11-deoxy TTX, 4,9-anhydro TTX were found in all tested tissues. Full article

Acid-soluble collagen (ASC) and pepsin-soluble collagen (PSC) from the skin of river puffer (ASC-RP and PSC-RP) and tiger puffer (ASC-TP and PSC-TP) were extracted and physicochemically examined. Denaturation temperature (T_d) for all the collagens was found to be 25.5–29.5 °C, which was lower than that of calf skin collagen (35.9 °C). Electrophoretic patterns indicated all four samples were type I collagen with molecular form of (α₁)₂α₂. FTIR spectra confirmed the extracted collagens had a triple-helical structure, and that the degree of hydrogen bonding in ASC was higher than PSC. All the extracted collagens could aggregate into fibrils with D-periodicity. The fibril formation rate of ASC-RP and PSC-RP was slightly higher than ASC-TP and PSC-TP. Turbidity analysis revealed an increase in fibril formation rate when adding a low concentration of NaCl (less than 300 mM). The fibril formation ability was suppressed with further increasing of NaCl concentration, as illustrated by a reduction in the turbidity and formation degree. SEM analysis confirmed the well-formed interwoven structure of collagen fibrils after 24 h of incubation. Summarizing the experimental results suggested that the extracted collagens from the skin of river puffer and tiger puffer could be considered a viable substitute to mammalian-derived collagens for further use in biomaterial applications. Full article

Species discrimination among three kinds of puffer fish, Takifugu obscurus, Takifugu flavidus and Takifugu rubripes, was conducted using an electronic nose combined with olfactory sensory evaluation. All data were treated by multivariate data processing based on principal component analysis (PCA) and discriminant factor analysis (DFA). The results showed the discriminant model by PCA method and DFA method. Using PCA and DFA, it was shown that the electronic nose was able to reasonably distinguish between each of the eleven puffer fish groups, with a discrimination index of 85. The olfactory sensory evaluation was undertaken in accordance to Sensory analysis—Methodology—Initiation and training of assessors in the detection and recognition of odors (BS ISO 5496-2006), and the results showed that the evaluation was able to identify puffer fish samples according to their species, geographical origin and age. Results from this analysis demonstrate that the E-nose can be used to complement the discrimination of odors by sensory evaluation from the three species of puffer fish studied here. Full article