MS-222对鳊鱼麻醉保活运输效果的研究

为研究MS-222对鳊鱼保活运输的影响,分析比较了在不同质量浓度MS-222(0、20、40、60、80、100 mg/L和120 mg/L)、不同水温(2、7、15、20℃)和不同鱼水质量比(2∶1、1∶1、1∶3、1∶5)下鳊鱼的存活率,从而确定及筛选最佳的保活运输条件,并检测和分析在保活运输试验中水质指标和鱼体生化指标的变化和影响。试验结果显示,当MS-222质量浓度为60 mg/L、水温7℃、鱼水比1∶3时,保活时间最长,鱼体存活率最高;随着保活时间的延长,水体指标中氨氮含量、微生物、pH均呈上升趋势,而溶解氧水平则呈下降趋势;在鱼体指标中,肌肉中糖原、pH下降,乳酸含量上升;在血液指标中乳酸脱氢酶、谷草转氨酶、血糖、尿素和肌酐均显著增加(P<0.05),说明随着保活时间的延长,鱼体肝脏和肾脏组织代谢水平受到一定的影响,但其变化幅度均小于对照组。研究结果表明,在鳊鱼保活过程中可适当使用MS-222麻醉剂以延长存活时间和提高存活率。     

团头鲂肠黏膜益生乳酸菌的分离及体外抗逆性研究

从团头鲂肠黏膜上分离筛选出2株对嗜水气单胞菌有较强的抑制作用的乳酸菌菌株JK-1和JK-2,通过耐受胆盐、耐受pH值、耐受蛋白酶和耐高温等试验对这2株乳酸菌进行体外抗逆性试验研究.其中在胆盐耐受性试验中,JK-1和JK-2在胆盐浓度0.4%、培养4 h时仍有35%以上的存活率;在pH值耐受性试验时,2株乳酸菌均可在一定的酸性和碱性条件下存活;胰蛋白酶对2株菌的存活率没有影响;在70 ℃的高温中,2株乳酸菌均有一定的耐受性.     

Sensory Characteristics of Threadfin Bream (Nemipterus japonicus) Hydrolysate

ABSTRACT

Threadfin bream (Nemipterus japonicus) spray-dried hydro-lysate was prepared using Alcalase at predetermined optimum hydrolysis conditions consisting of pH 8.5, 60°C, 2% enzyme, and 2 h hydrolysis. The hydrolysate was evaluated for its preferred concentration in rice porridge. Its acceptability was compared with sauces and enzyme-treated rice and vegetable hydrolysate. The preferred concentration in rice porridge was found to be 3% (w/v) and bitterness increased with concentration of hydrolysate. Threadfin bream hydrolysate was preferred as much as soy sauce; however, it received a lower score for taste compared to fish sauce. In terms of color, threadfin bream hydrolysate received significantly (p < 0.05) lower score than Flavorzyme and Alcalase treated rice hydrolysate and Vegetable hydrolysate. Low preference to the hydrolysate could probably be due to its greenish yellow color in which the common color for flavorants are brownish. For overall acceptability, no significant difference was observed between threadfin bream hydrolysate and Alcalase-treated rice hydrolysate but was significantly lower than vegetable hydrolysate and Flavorzyme-treated rice hydrolysate.

The hydrolysis of threadfin bream with Alcalase produced hydrolysate having a combination of bitter, umami, salty, sweet and sour tastes with fishy flavor. Bitterness and umami were rated as having an intermediate intensity, salty as between weak and intermediate, and sour and sweet as weak. The three basic tastes for hydrolysate were bitter, umami and salty, with umami and bitterness being the determining tastes.     

Effects of dietary caffeine on growth,body composition,somatic indexes,and cerebral distribution of acetyl‐cholinesterase and nitric oxide synthase in gilthead sea bream (Sparus aurata), reared in winter temperature

This study aims at examining the effect of caffeine administration on growth, feed efficiency, and consumption of sea bream (Sparus aurata), reared in winter temperatures. Moreover, it is questioned whether caffeine has a central action in the brain and its effects are partly mediated via central brain mechanisms. For this, we studied the influences of caffeine treatment on the cerebral pattern of the cholinergic neurotransmission and the novel neuromodulator nitric oxide (NO), by means of acetyl‐cholinesterase (AchE) and nitric oxide synthase (NOS) histochemistry. Five different diets containing 0.0, 0.1, 1.0, 2.0 and 5.0 g caffeine kg^?1 of diet were administrated to five groups of fish. Caffeine adversely affected sea‐bream growth at a concentration higher than 1 g kg^?1 diet and increased feed conversion ratio in the treatments of 2 and 5 g kg^?1 (P < 0.05). The daily consumption of feeds was similar to all groups, indicating that caffeine did not influence diet palatability. AChE‐ and NADPH‐diaphorase histochemistry showed densely labeled cells and fibers mainly in dorsal telencephalon, preoptic, pretectal, hypothalamic areas, optic tectum, reticular formation, cerebellum and motor nuclei. When compared with matched caffeine‐treated animals, no differences in the histochemical pattern and cell densities of cerebral AChE and NADPH‐diaphorase were found.     

鳊鱼鱼糜保藏特性的研究

对在不同温度（-80％,-20℃,0℃,5℃）下保藏了一个月的鳊鱼鱼糜品质进行比较和研究,检测了凝胶强度、挥发性盐基氮、肌球蛋白含量,保藏效果为：一80℃效果最好,-20℃其次,0℃一般,5℃变质严重,即温度越低,保藏效果越好;通过化学作用力、凝胶溶解率、巯基含量、SDS-聚丙烯酰胺凝胶电泳（SDS-PAGE）分析品质差异原因,结果发现：在鳊鱼鱼糜蛋白质构象稳定时,离子键作用力强、总巯基含量高。在品质较差的鱼糜中,疏水键和非二硫键较强。     

Dietary eicosapentaenoic acid requirement of juvenile rock bream,Oplegnathus fasciatus

A feeding trial was conducted to evaluate the optimum dietary level of eicosapentaenoic acid (EPA, 20:5n‐3) based on growth and non‐specific immune responses in juvenile rock bream. A basal diet without EPA supplementation was used as a control, and six other diets were prepared by supplementing with 4, 8, 12, 16, 20 or 40 g of EPA per kg diet. The actual EPA concentrations of the diets were 0.5, 4.3, 8.5, 13.0, 16.8, 21.0 and 41.2 g of EPA per kg diet, and the diets were abbreviated as EPA_0.5, EPA_4.3, EPA_8.5, EPA_13.0, EPA_16.8, EPA_21.0 and EPA_41.2, respectively. Triplicate groups of fish averaging 1.06 ± 0.01 g (mean ± SD) were fed one of the seven experimental diets at the apparent satiation for 8 weeks. At the end of the feeding trial, weight gain, specific growth rate and feed efficiency of fish fed EPA_16.8, EPA_21.0 and EPA_41.2 diets were significantly higher than those of fish fed EPA_0.5, EPA_4.3, EPA_8.5 and EPA_13.0 diets (p < .05). Superoxide dismutase activity of fish fed EPA_16.8, EPA_21.0 and EPA_41.2 diets were significantly higher than those of fish fed EPA_0.5, EPA_4.3 and EPA_8.5 diets. Fish fed EPA_21.0 and EPA_41.2 diets showed significantly higher lysozyme activity than did fish fed EPA_0.5, EPA_4.3, EPA_8.5 and EPA_13.0 diets. The broken‐line analysis of weight gain indicated that the optimum dietary EPA level was 16.7 g/kg diet. These results suggested that the optimum dietary EPA level in juvenile rock bream could be greater than 16.7 g/kg diet but less than or equal to 16.8 g/kg diet based on the broken‐line analysis and the ANOVA test of weight gain.     

Characterization of the DNA nucleotide sequences in the genome of red sea bream iridoviruses isolated in Korea

The nucleotide sequences of DNA fragments amplified by polymerase chain reaction (PCR) from four different genomic regions of nine red sea bream iridoviruses (RSIVs) isolated from different species of fish, different areas and in different years in Korea were compared with the reported reference sequences. One isolate, RSIV Namhae, showed 100% homology to the reference sequences, while the other eight isolates, which appeared to contain identical nucleotide sequences, showed 96.6–98.9% homology with reference sequences depending upon the target regions of PCR gene amplification. However, differences in nucleotide sequences were not apparent between the RSIVs isolated in different locations, in different years or in different host species. We also cloned and sequenced the 3′ end flanking region (K1) of the DNA polymerase (DPOL) gene using the cassette ligation-mediated PCR method. This sequence was 4436-bp long and possessed two open reading frames (ORF-1 and ORF-2) oriented in opposite directions. The putative proteins encoded by these two ORFs could not be characterized by comparison with the proteins of other species in the data banks. The presence of the ribonucleotide reductase small subunit (RNRS) gene at the 3′ end of the K1 region allowed us to determine that these two genes, RNRS and DPOL, are separated 5508 bp and oriented in the same direction in the genome of RSIV. Moreover, it is of interest that a PstI-restriction fragment, of which the sequence but not the location within the RSIV genome had previously been reported, is located at nucleotide positions from 1096 to 2054, extending from within the ORF-1 region, spanning the intervening sequence between ORF-1 and ORF-2, and extending into the ORF-2 region. Various repeating sequences up to 86 bp were present at the 3′ ends of ORFs, especially within the nucleotide sequences at the 3′ terminus of ORF-2. No similarities were detected when the DNA sequences of the K1 region were compared to the DNA sequences of a repetitive element in the genome of other iridoviruses.     

双向选择对团头鲂生化遗传变异的影响↑（*）

本文报导双向选择对团头鲂生化遗传变异的影响。试验材料鱼包括来自淤泥湖的原种，１９８６－１９９４年群体选育的第四代（“选育 Ｆ４”），以及１９９１、１９９４年连续兄妹杂交的第二代（“近交Ｆ２”）。计检测了８种同工酶，１９个位点。三群体的多态座位比例一致（５．２６％），但平均杂合度趋异。“选育Ｆ４”平均杂合度最高（０．０２１３），“近交Ｆ２”最低（０．０１７４）。经４代选育，平均杂合度增加４％，而经２代近交，平均杂合度降低１５％。     

Expression of recombinant triangular bream (Megalobrama terminalis) pre-IGF-I in Escherichia coli

The insulin-like growth factor I (IGF-I) cDNA (GenBank Accession No. AY247412) of triangular bream (Megalobrama terminalis) was expressed for the first time in Escherichia coli. To construct the expression plasmid, the IGF-I cDNA was subcloned into prokaryotic-expressing vector pGEX-4T-1. The E.coli JM109 was transformed with the recombinant plasmid pGEX-4T-1-IGF-I, and the transgene expression was observed after being induced with isopropyl-β-D-thiogalactoside (IPTG). The results of SDS polyacrylamide gel electrophoresis (SDS-PAGE) and Western blotting indicated that the recombinant fusion protein had immune activity and the molecular weight was about 47 kDa. The results of SDS-PAGE and thin layer scanning showed that the yield of fusion protein had been enlarged with prolonging time. When the time of induced expression was 1, 2, 3, 4, 5, and 6 h, the expression amount was approximately 1.4, 4.3, 8.1, 11.3, 16.3 and 18.8% of total bacterial protein respectively.