Effects of dietary squid viscera meal on growth and cadmium accumulation in tissues of Japanese seabass, Lateolabrax japonicus (Cuvier 1828)

Cadmium (Cd) is a toxic environmental pollutant with a long biological half‐life and can produce both hepatic and renal injuries in mammals and fish. Squid viscera meal (SVM), an effective attractant for aquatic animals, is widely used as an ingredient in aquafeeds. However, SVM is rich in Cd and its complexes. A study was conducted to evaluate the effects of dietary SVM on the growth and Cd deposition in tissues of Japanese seabass, Lateolabrax japonicus. Three practical diets were formulated to contain 0, 50 and 100 g SVM kg^?1 diet, respectively, containing 0.21, 7.26 and 12.08 mg Cd kg^?1 diet. Each diet was randomly assigned to triplicate groups of 80 Japanese seabass (mean initial weight, 10.89±0.21 g) in floating sea cages (1.5 × 1.5 × 2.0 m). Fish were fed twice daily (06:30 and 16:30 hours) to satiation for 8 weeks. The results showed that there were no significant differences in fish survival among three dietary treatments, but significant higher specific growth rates (SGR) were observed in the fish fed diets with 50 or 100 g SVM kg^?1 diet than that from the control group (P<0.05). The Cd concentrations in the kidney, liver and gill were found in a decreasing order at each treatment, and positively correlated with dietary Cd levels. Fish fed diets with 50 and 100 g SVM kg^?1 diet had significantly higher Cd accumulations in the kidney (3.25, 5.85 mg kg^?1), liver (0.76, 1.26 mg kg^?1) and gill (0.42, 0.58 mg kg^?1) compared with the control group (0.82, 0.34 and 0.32 mg kg^?1 respectively) (P<0.05). The Cd concentration in fish muscle; however, was undetectable in any treatment. Therefore, based on these results, accumulation of Cd in edible tissue (muscle) of farmed Japanese seabass is not a food safety issue. However, long‐term feeding of diets with SVM may result in accumulation of Cd in the kidneys, liver and gills of fish.     

Purification of serine carboxypeptidase from the hepatopancreas of Japanese common squid Todarodes pacificus and its application for elimination of bitterness from bitter peptides

ABSTRACT:   An acidic serine carboxypeptidase (CPase Tpa) from the hepatopancreas of Japanese common squid Todarodes pacificus was purified. Purified CPase Tpa had a molecular mass of 36 kDa on sodium dodecylsulfate–polyacrylamide gel electrophoresis, and an isoelectric point of 6.0. The optimum pH of CPase Tpa was pH 4.0. In investigating the specificity of CPase Tpa for several peptide substances, it was found that peptides with hydrophobic or bulky amino acid residues at the P₁ position reacted well. The enzymatic activity was almost completely inhibited by p -chloromercuribenzoic acid, monoiodoacetic acid, diisopropylfluorophosphate and HgCl₂. This is the basis for its grouping in the serine carboxypeptidase family (EC 3. 4. 16. 5). The substrate specificity of CPase Tpa can be used to eliminate the bitterness of bitter peptides. In this study, the bitterness-reductive effect using bitter peptides prepared by hydrolyzing soy protein, casein and corn gluten with pepsin or trypsin was tested. The bitterness of soy peptide digested with pepsin was completely eliminated by treatment with CPase Tpa, whereas the bitterness of casein digested with trypsin and corn peptide digested with pepsin were somewhat less efficient. On the basis of these results, it is anticipated that CPase Tpa would be effective in eliminating the bitterness of some bitter peptides.     

广东沿海贝类4种重金属含量分析和评价

根据2007年6～9月对广东沿海4种贝类养殖区90个样品的检测结果,研究了贝类体内重金属的含量和累积,对贝类的质量安全进行评价。结果表明：（1）菲律宾蛤仔Ruditapes philippinarum体内含量大小顺序为铜（Cu）〉镉（Cd）〉铬（Cr）〉铅（Pb）,太平洋牡蛎Crassostreagigas和近江牡蛎C．rivularis的大小顺序都是Cu〉Cd〉Pb〉Cr,而翡翠贻贝Pernaviridis的大小顺序则是Cu〉Pb〉Cd〉Cr;（2）菲律宾蛤仔、太平洋牡蛎和翡翠贻贝未受重金属污染,但部分近江牡蛎体中Cd和Cu含量已超过中国农业行业标准“无公害食品：水产品有毒有害物质限量”标准,应该引起重视。     

不同海域鲍体镉分布特征与健康风险评价

文章对中国部分海域鲍体镉（cd）的质量分数与分布特征进行了分析讨论,并对鲍体cd对人体的健康风险进行了评价。结果表明,1）鲍体W（Cd）总体上呈正态分布,其平均值为0．88mg·kg^-1,变化范围为0．06-1 2．02mg·kg^-1,其中广东、福建、山东和辽宁海域鲍体W（Cd）分别为（0．42±0．21）mg·kg^-1、（0．61±0．27）mg·kg^-1、（1．21±0．35）mg·kg^-1和（1．52±0．20）mg·kg^-1,不同海域鲍体W（Cd）差异显著（P〈0．05）。2）鲍体W（Cd）高于鱼类、头足类和甲壳类海洋生物,与贝类产品埘（Cd）相当;鲍体W（Cd）与栖息环境中cd的污染程度有密切关系。3）鲍体cd对人体的致癌性年风险指数低于国际辐射防护委员会推荐的风险水平,通过鲍膳食途径的人体cd暴露量低于世界卫生组织／联合国粮食和农业组织的食品添加剂联合专家委员会推荐的暂定每周耐受摄人量推荐值。研究结果对于鲍的健康养殖和安全消费具有指导意义。     

Differential tissue accumulation of arsenic and heavy metals from diets in three edible fish species

Three different commercial fish species Odontesthes bonariensis, Rhamdia quelen and Oreochromis niloticus and fish feed were collected from four aquaculture farms. Heavy metal (Cd, Cr, Cu, Fe, Mn, Pb and Zn) and arsenic concentration were determined by inductively coupled plasma–optical emission spectrometry (ICP‐OES) in muscle, liver, gonad, skin, scale and fat from fish and in feed diets. Arsenic concentration was found in different tissues differing between species and within O. bonariensis. Cd was differentially accumulated in liver in O. bonariensis and R. quelen; however, in O. niloticus Cd was found in muscle and scales. Higher concentrations of Cr were determined in skin and scales of O. bonariensis and O. niloticus. Cu, Fe, Mn and Zn were found in all tissues being Cu and Fe concentrations higher in liver. Mn was differentially accumulated in O. bonariensis scales, however in R. quelen no significant differences were found and in O. niloticus liver was the main accumulation tissue. Zn concentration was higher in gonad, skin and liver from R. quelen and O. bonariensis, and in O. niloticus the highest concentration was found in scales. All the results were below the international limits for food safety except for the concentration of Cd in muscle and scales of O. niloticus.     

Differences in food availability for Japanese sardine larvae between the frontal region and the waters on the offshore side of Kuroshio

The availability of food for larvae of the Japanese sardine, Sardinops melanostictus , was investigated in the Kuroshio frontal region and the waters on the offshore side of the Kuroshio, the Pacific coast of central Japan, in March 1990 and 1991, respectively. Food availability was assessed by changes in biomass and production of nauplii and small copepods, and RNA/DNA ratios of the larvae during about 2.5 days (the frontal region) or 3 days (the offshore waters) of tracking a drifter released in a pitch of the larvae. The biomas of the nauplii tended to increase with time in the frontal region and to decrease in the waters on the offshore side of the Kuroshio during the drifter tracking periods. The production of small copepods including nauplii in the waters on the offshore de of the kuroshio was 14% of that in the frontal region. The sum of the mean food requirements of the carnivorous macrozooplankters and sardine larvae was 11% of the production of small copepods including nauplii in the frontal region, compared with 136% in the waters offshore of the Kuroshio. The RNA/DNA ratios of postlarvae smaller than 8 mm in the frontal reqion were significantly higher than those in the waters on the offshore side of the Kuroshio ( P < 0.001) It is considered that the food availability for sardine larvae was relatively high in the frontal region and low in the waters on the offshore side of the Kuroshio. The food availability for the larvae probably deteriorated with the offshore shift of the main spawning ground from the frontal region to the waters on the offshore side of the Kuroshio in the latter half of the 1980s.     

浒苔对海水中重金属的富集研究及食用安全风险评估

研究了浒苔（Enteromorpha prolifera）分别在镉（Cd2＋,浓度分别为5、20、80μg/L）和铅（Pb2＋,浓度分别为5、20、80μg/L）及对照组的海水中培养时,2种重金属在其体内的积累规律。结果表明,浒苔对Cd和Pb具有较强的富集能力,对Cd的富集倍数范围为558～1882倍,对Pb的富集倍数范围为6295～11080倍。本研究并对富集Pb和Cd后浒苔的食用安全进行风险评估。     

Feeding on the edge: δ13C analysis of a macrofauna food web from disappearing seagrass beds in a polluted urban harbour – implications for biomonitoring and restoration efforts

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