过饱和溶氧对大菱鲆生长及消化酶的影响

探讨工程化养殖中过饱和溶氧对大菱鲆生长的影响,通过充入液态氧与空气,使试验水体的溶氧分别达到过饱和溶氧水平(12±1)mg/L和(14±1)mg/L,正常溶氧水平(7.0±0.5)mg/L.结果显示,过饱和溶氧组的大菱鲆生长速度及饵料利用率明显高于正常溶氧组(p<0.05),而在过饱和溶氧条件下与正常溶氧条件下大菱鲆的丰满度无显著差异(P>0.05).对大菱鲆胃、肠道消化酶、脂肪酶与淀粉酶的分析发现,大菱鲆胃蛋白酶活性在过饱和溶氧条件下较正常溶氧有明显提高(p<0.05),而脂肪酶与淀粉酶的酶活力未得到显著性提高(p>0.05).     

Isolation of a highly pathogenic Vibrio pelagius strain associated with mass mortalities of turbot,Scophthalmus maximus (L.), larvae

A bacterial strain, characterized as Vibrio pelagius (Hq 222), was isolated from a turbot, Scophthalmus maximus (L.), larvae mass mortality in a commercial fish farm in Spain. Turbot larvae, post-larvae (0.2 g) and juveniles (5 and 15 g) were experimentally infected. The bacterium appeared to be very virulent for larvae and post-larvae, LD50 being < 5 bacteria mL(-1) for larvae 1 week post-infection and 3.9 x 10(5) bacteria mL(-1) in post-larvae at day 12 post-infection. The bacterial strain was recovered in pure culture from the internal organs of infected fish. Histological lesions in post-larvae exhibited swelling and necrosis of gill secondary lamellae, sloughing of intestinal mucosa and necrosis of haematopoietic tissue in the kidney. Vibrio pelagius (Hq 222) was able to grow in sterile sea water when incubated at room temperature or at 15 degrees C. Vibrio pelagius (Hq 222) was more adherent to the turbot cell lines TV-1 and TF than Escherichia coli. In both cell lines, the number of adhered bacteria increased with incubation time.     

Purification and characterization of stomach protease from the turbot (Scophthalmus maximus L.)

Proteolytic activity in the different parts of the digestive tract of the turbot (Scophthalmus maximus L.) were studied in this work. One pure protease was isolated from turbot stomach and its behavior was studied. Results showed the optimum pH for proteases in the different parts of the digestive tract of the turbot were pH 2.0 for the stomach, pH 8.0 for the pylorus cecum, pH 8.0 for the foregut, pH 8.5 for the midgut, and pH 8.0 for the hindgut. The activity of proteases in the different parts of the digestive tract were in the sequence pylorus cecum protease > stomach protease > foregut protease > midgut protease > hindgut protease. The stomach protease was purified by ammonium sulfate precipitation and column chromatography on DEAE-Sepharose F.F. and Sephadex G-100. The purified enzyme gave a single band in SDS-polyacrylamide gel electrophoresis (SDS-PAGE). Its molecular weight was found to be approximately 42,000 Da. The enzyme is stable at pH 1.0–9.0 and at temperatures below 40°C. Its activity was maximum at pH 2.0 and 40°C. When reaction time was prolonged the optimum temperature of the enzyme tended to decline. The enzyme was activated by Mn²⁺ and Cu²⁺ and inactivated by Fe³⁺. It was fully inhibited by pepstatin and partially inhibited by PMSF, TPCK, PCMB, and NBS. These results imply the enzyme is a pepsin.     

溶藻胶弧菌脂多糖对大菱鲆白细胞吞噬活性的影响

针对溶藻胶弧菌脂多糖在增强大菱鲆非特异性免疫功能、提高机体抗病能力方面的作用机理,开展了研究工作。实验中以浓度为2．4mg／ml 溶藻胶弧菌脂多糖,通过口服和注射的方式接种平均体重47．2g 大菱鲆幼鱼,接种后第7、15、 30天,分别采血根据血细胞吞噬作用检测结果计算吞噬百分比和吞噬指数。结果显示,溶藻胶弧菌脂多糖对白细胞吞噬活性有明显促进作用,在增强白细胞的吞噬能力方面作用不显著。     

一种吻蛭类大鱼蛭在大菱鲆鱼体上的感染

在山东省威海崮山育苗场发现大菱鲆成鱼及幼鱼鱼体感染寄生虫，受感染的鱼由于处于感染初期，并经过及时的处理，所占比例较低。病鱼症状为鱼体体色变黑、瘦弱、离群、不摄食甚至死亡。寄生虫寄生于大菱鲆的体表及鳃部，虫体黑褐色，全长40～50mm。经鉴定，该寄生虫属于环节动物门(Annelida)，蛭纲(Hirudinea)，吻蛭目(Rhynochobdellida Blanchard)，鱼蛭科(Piscicolidae Johnson)，鱼蛭属(Piscicola Blainville)，大鱼蛭(Pisciola magna Yang)。     

饲料Vc对大菱鲆非特异性免疫力的影响

X用维生素C（Vc）含量为0～2500mg／kg的配合饲料连续投喂大菱鲆70d后，测定大菱鲆血液白细胞的总数、吞噬活性、血清溶菌酶活性和总补体活性。结果表明，饲料中Vc含量增加到250mg／kg，白细胞总数明显增加，进一步提高Vc含量，白细胞总数没有显著变化；血清溶菌酶活性在Vc含量为250mg／kg时最高，其他各组无显著性差异；添加Vc的各试验组的总补体活性明显地高于对照组，但是添加Vc的各组之间的总补体活性没有显著性差别；Vc含量对白细胞的吞噬活性没有影响。     

Effects of acute temperature decreases on turbot fry and juveniles

Turbot fry (10–20 mm) and juveniles (85–110 mm) were transferred directly from 16.0–16.5 C to 1.0 C, 2.5 C, 5.5 C or 8.0 C seawater. The fry were more sensitive to cold water than juveniles. The fry survived for 1 week at 8.0 C but not at 5.5 C, whereas juveniles survived at 5.5 C but not at 2.5 C. Transfer of juveniles to 1.0 C and 2.5 C seawater caused a high mortality, a marked increase in plasma Cl^- concentration, decrease in muscle water content, and hyperglycaemia. Acclimation to 5.5 C (juveniles) or 8.0 C (fry and juveniles) markedly reduced the sensitivity to 1.0 C exposure.     

Assessment of marine thraustochytrid <Emphasis Type="Italic">Schizochytrium limacinum</Emphasis> OUC88 for mariculture by enriched feeds

ABSTRACT:   In the present study, Schizochytrium limacinum OUC88, a thraustochytrid with high content of docosahexaenoic acid (DHA, 22:6 n −3), was used as feed for rotifer Brachionus plicatilis and Artemia franciscana . The rotifer and Artemia were harvested at 3, 6, 9, 12, 18, and 24-h intervals, analyzed for fatty acid composition, and compared with the control which fed on yeast only. The highest DHA content resulted from an enrichment period of 12 h for both fed organisms, reached 13.4 and 10.9% of the total fatty acids (TFAs) in rotifers and Artemia nauplii, respectively, and the DHA level reduced sharply if enrichment time was longer than 12 h. The pseudoalbinism rate of turbot Scophthalmus maximus juveniles fed enriched rotifers and Artemia nauplii reduced greatly (40% lower than in control group). Thus, enrichment of rotifers and Artemia nauplii by DHA-rich Schizochytrium limacinum OUC88 may provide a practical strategy for feeding fish juveniles in aquaculture.     

大菱鲆AFLP分析体系的建立

本研究构建了大菱鲆扩增片段长度多态性(AFLP)分析体系,对DNA提取、双酶切反应、连接反应、预扩增反应、选择性扩增反应和银染等步骤进行了分析。结果表明,用EcoRI/MseI双酶切、核心序列加3个选择性碱基的选择性扩增引物、1∶6(w∶w)的EcoRI端与MseI端选择性扩增引物比和20μl选择性扩增体积,可得到十分稳定的结果。所得产物经电泳和银染后可获得条带清晰、背景干扰小的图像。该体系的构建为AFLP技术在大菱鲆相关研究中的应用奠定了基础。     

Accuracy of pairwise methods in the reconstruction of family relationships, using molecular information from turbot (Scophthalmus maximus)

Many estimators and algorithms have been developed to infer the genealogical relationships from molecular marker data when there is no pedigree information. Most pairwise methods provide estimates in a continuous range that needs to be converted into genealogical relationships (namely full-sibs, half-sibs and unrelated) if there is a previous knowledge of the population structure. Transformations are usually based on arbitrary thresholds, but the possibility of correcting the coancestry estimates via explicit pedigree reconstruction methods has been suggested. Using molecular data for ten highly polymorphic microsatellite loci on a population of turbot (Scophthalmus maximus) with a known genealogy, the behaviour of four pairwise marker-based coancestry estimators and the molecular coancestry has been evaluated. The population consisted on 138 families with 4 full-sib individuals each and one family with 8 full-sib individuals (up to 15 half-sib families were also present due to the sharing of parents between some of the full-sibs families). Our results suggested that transforming the pairwise estimators and the molecular coancestry to family relationships through the establishment of thresholds performs slightly better than the explicit pedigree reconstruction method, when accuracy is measured in a pairwise basis. However, if joint relationships between more than two individuals were tested at a time, the threshold methods led to a high percentage of incongruous triads of full-sib individuals, with Mendelian incompatibilities appearing in congruous full-sib families (more than 70% and 60% in our study, respectively). The explicit pedigree reconstruction approach, due to its nature, is free from such problems. Therefore, the pedigree reconstruction approach seems to be a valuable tool to provide a congruent and compatible pedigree when the pairwise marker-based coancestry matrices or the molecular coancestry need to be transformed.