Molecular Characterization of the Von Willebrand Factor Type D Domain of Vitellogenin from Takifugu flavidus

The von Willebrand factor type D (VWD) domain in vitellogenin has recently been found to bind tetrodotoxin. The way in which this protein domain associates with tetrodotoxin and participates in transporting tetrodotoxin in vivo remains unclear. A cDNA fragment of the vitellogenin gene containing the VWD domain from pufferfish (Takifugu flavidus) (TfVWD) was cloned. Using in silico structural and docking analyses of the predicted protein, we determined that key amino acids (namely, Val¹¹⁵, ASP¹¹⁶, Val¹¹⁷, and Lys¹²²) in TfVWD mediate its binding to tetrodotoxin, which was supported by in vitro surface plasmon resonance analysis. Moreover, incubating recombinant rTfVWD together with tetrodotoxin attenuated its toxicity in vivo, further supporting protein–toxin binding and indicating associated toxicity-neutralizing effects. Finally, the expression profiling of TfVWD across different tissues and developmental stages indicated that its distribution patterns mirrored those of tetrodotoxin, suggesting that TfVWD may be involved in tetrodotoxin transport in pufferfish. For the first time, this study reveals the amino acids that mediate the binding of TfVWD to tetrodotoxin and provides a basis for further exploration of the molecular mechanisms underlying the enrichment and transfer of tetrodotoxin in pufferfish.     

暗纹东方鲀集约化养殖中的几种常见疾病的诊断、治疗及防治

本文报道了1995～1998年间作者在暗纹东方鲀集约化养殖中,对小瓜虫病、鲀异钩虫病、指环虫病、车轮虫病及细菌性疾病进行的诊断、治疗及防治方法,同时描述了各病的典型症状。本文为鉴别、治疗、防范暗纹东方鲀鱼病提供了依据,在集约化养殖中具有一定的应用价值。     

Calcium Requirement of Tiger Puffer Fed a Semi-Purified Diet

Juvenile tiger puffer (Takifugu rubripes) were fed semi-purified diets with graded levels (0–0.40%) of calcium (Ca) supplements for 8 weeks at a temperature of 23.0–25.5 °C. At the end of the feeding experiment, average final body weight increased with increasing dietary Ca levels. A diet without Ca supplement resulted in poor average final body weight and 0.05% dietary Ca supplement could not significantly improve the growth. However, supplemental Ca levels of 0.10–0.40% significantly increased growth. Dietary Ca supplements of 0.10% or more also improved the feed efficiency in tiger puffer. Ca and phosphorus contents of the bone were independent of dietary Ca supplements. However, 0.40% Ca in the diet decreased the zinc and manganese contents of bone. Results indicated that supplemental Ca levels of 0.10–0.20% in a semi-purified diet were required to maintain normal growth, feed utilization and bone mineralization of tiger puffer.     

红鳍东方鲀的人工繁殖试验

采用网箱养殖四年的红鳍东方鲀经过颗粒状的促黄体生成激素释放素(LH-RH)的植埋,促使性腺成熟,再通过注射绒毛膜促性腺激素(HCG)与大麻哈鱼脑垂体混合液诱导排卵,采卵后进行人工授精,得到红鳍东方鲀受精卵,孵化后得到红鳍东方鲀仔鱼。     

红鳍东方鲀开口饵料筛选试验

本文选择水产育苗常用的幼体开口饵料──小球藻、轮虫、卤虫幼体、蛋黄对初孵红鳍东方进行开口饵料筛选试验。结果表明：用小球藻和轮虫混合投喂效果最好,其余依次为轮虫、卤虫幼体、蛋黄。     

循环水养殖系统生物滤器负荷挂膜技术

循环水养殖系统启动运行前往往需要经过一段时间的生物膜预培养,使生物膜达到成熟稳定,从而保证系统的水质净化功能。本研究通过养殖试验,研究了生物滤器负荷挂膜的技术方法,以期实现生物膜的快速成熟和系统的快速启动。为此,构建了6组循环水系统组成的养殖车间,建成后立即投入试验生产。试验为期120 d,养殖种类为红鳍东方鲀,初始放养平均体重(632.5±2.26)g。期间,红鳍东方鲀平均增重29.91%,养殖成活率98.7%,养殖密度由(19.34±1.89)kg/m3增加到(32.17±3.40)kg/m3,投饵率由0.2%增加到0.5%–0.7%,每日换水量由50%逐渐减至10%。结果表明,在生物膜的生长期,通过对投饵量及新水补充量的有效调节,可以把养殖水体中的氨氮和亚硝氮浓度控制在安全范围以内,以保证养殖鱼类的生长。生物膜在50天左右达到完全成熟,此后便可依靠生物膜的净化作用将氨氮浓度控制在0.5?1.2 mg/L、亚硝氮浓度控制在0.2?0.5 mg/L、pH值控制在6.5–7.5、COD值低于4 mg/L、细菌总数控制在800–2100 cell/ml的安全范围内。利用生物滤器负荷挂膜技术,在合理调控水质指标的条件下,循环水养殖系统建成后可以立即投入生产,实现生物滤器挂膜与养殖生产的同步进行。     

Dietary protein requirement of juvenile obscure puffer,Takifugu obscurus

A 10‐week feeding experiment was conducted to determine the optimum dietary protein requirement of juvenile obscure puffer (Takifugu obscurus). Six isoenergetic (20 MJ kg^?1 gross energy) diets were formulated to contain graded levels of 34%, 38%, 42%, 46%, 50% or 54% crude protein (as dry matter basis). The results showed final body weight, weight gain and specific growth rate (SGR) increased significantly with increasing protein levels up to 42% and then decreased thereafer. Second‐order polynomial regression analysis (y = ?0.0024x² + 0.1788x ? 1.3196, R² = 0.9032) indicated a maximum SGR at protein level of 37%. Feed conversion ratio (FCR) decreased with increasing levels of dietary protein up to 42% and increased thereafter. Second‐order polynomial regression analysis (y = 0.0054x² ? 0.4351x + 10.391, R² = 0.753) indicated a minimum FCR at protein level of 40%. Protein efficiency ratio (PER) of fish fed the 34%, 38% and 42% diets was significantly higher than that of fish fed the 46%, 50% and 54% diets, and broken‐line analysis indicated PER tended to decrease when dietary protein level was higher than 40%. Generally, whole body lipid content, total cholesterol, low‐density lipoprotein cholesterol and triacylglycerol decreased with increasing levels of dietary protein. Fish fed the 42% protein diet showed the highest essential amino acids (histidine, isoleucine, leucine, lysine and threonine) and non‐essential amino acids (aspartic acid and glutamic acid) in muscle. Based on the second‐degree polynomial regression analysis of SGR and FCR and broken‐line analysis of PER, the optimal dietary protein level of obscure puffer is estimated to be between 37% and 40% (% as dry matter basis).     

ACE Inhibitory Peptide from Skin Collagen Hydrolysate of Takifugu bimaculatus as Potential for Protecting HUVECs Injury

Angiotensin-I-converting enzyme (ACE) is a crucial enzyme or receptor that catalyzes the generation of potent vasopressor angiotensin II (Ang II). ACE inhibitory peptides from fish showed effective ACE inhibitory activity. In this study, we reported an ACE inhibitory peptide from Takifugu bimaculatus (T. bimaculatus), which was obtained by molecular docking with acid-soluble collagen (ASC) hydrolysate of T. bimaculatus. The antihypertensive effects and potential mechanism were conducted using Ang-II-induced human umbilical vein endothelial cells (HUVECs) as a model. The results showed that FNLRMQ alleviated the viability and facilitated apoptosis of Ang-II-induced HUVECs. Further research suggested that FNLRMQ may protect Ang-II-induced endothelial injury by regulating Nrf2/HO-1 and PI3K/Akt/eNOS signaling pathways. This study, herein, reveals that collagen peptide FNLRMQ could be used as a potential candidate compound for antihypertensive treatment, and could provide scientific evidence for the high-value utilization of marine resources including T. bimaculatus.     

微卫星标记对红鳍东方鲀繁殖的指导应用及遗传分析

利用已有设计的20个具有多态性的微卫星标记对16尾红鳍东方鲀亲鱼(10尾♂,6尾♀)的有效等位基因数、观望杂合度、期望杂合度、多态信息含量、遗传相似性系数、遗传距离等进行了检测.据此设计了10对亲鱼配组,获得10个子代家系.其中母本中16和8号的平均有效等位基因数和平均期望杂合度较其他亲本高,将其分别与3个父本配组,其他则参照遗传距离进行配组.于次年,对F110个家系的体质量、体长均值进行了比对,发现16♀与11♂配组得到的子代体质量、体长均值为最大.8♀和10♂配组得到的子代体质量、体长均值最小.结果表明,红鳍东方鲀子代杂种优势与亲本个体差异有关.