饥饿和重摄食对鲤鱼脂蛋白脂肪酶活性的影响

采用对硝基苯酚法测定正常摄食、饥饿(14 d)和重摄食(3 d)状态下鲤鱼不同组织和器官中脂肪酶及脂蛋白脂肪酶(lipoproteinlipase,LPL)的活性。结果显示:与正常摄食相比,饥饿鲤鱼肌肉、脂肪和心脏中脂肪酶比活力显著下降(P0.05),但脂肪和心脏中LPL比活力显著升高(P0.05);除脂肪中LPL外,重摄食3d的鲤鱼各组织和器官中脂肪酶和LPL比活力比正常摄食和饥饿鲤鱼均显著升高(P0.05),有明显的补偿作用。     

Isolation of infectious microalga Prototheca wickerhamii from a carp (Cyprinus carpio) – a first confirmed case report of protothecosis in a fish

Protothecosis is a rare infection caused by environmentally ubiquitous achlorophyllic microalgae of the genus Prototheca. Here, we describe a first case of protothecosis in a carp (Cyprinus carpio), which is at the same time the first case of protothecosis in a fish, confirmed by phenotype‐ and molecular‐based methods, including PCR sequencing of the rDNA cluster and protein profiling using matrix‐assisted laser desorption ionization time‐of‐flight mass spectrometry.     

Comparative functional responses of native and high‐impacting invasive fishes: impact predictions for native prey populations

Comparative functional responses (FRs) can predict impacts of invasive species, including piscivorous fishes, via quantifying their depletion of native food resources as a function of prey density. The utility of FRs for predicting impacts on prey populations by invasive fishes of different trophic guilds was tested here by comparing the FRs of the invaders Cyprinus carpio and Carassius auratus, with three native, trophically analogous fishes, Barbus barbus, Squalius cephalus and Tinca tinca. Chironomid larvae and Gammarus pulex were used as prey items. Predictions, developed from studies on the foraging of C. carpio and C. auratus in the literature, were that the invaders would have significantly higher consumption rates for chironomids than the native fishes, but not for G. pulex. Mean consumption rates for chironomids were significantly lower for both invaders than B. barbus and S. cephalus, but were similar to T. tinca. Barbus barbus had a significantly lower consumption rate of G. pulex than both invaders, but there were no significant differences between S. cephalus, T. tinca and the invaders. All FRs were type II, with FR curves for the invaders preying upon chironomids never being significantly higher than the native fishes, contrary to predictions. For G. pulex, some significant differences were apparent between the invaders and native fishes, but again were contrary to predictions. These results indicated that when predation impacts of invasive fishes could also be a function of their population density and body sizes, these parameters should be incorporated into FR models to improve impact predictions.     

饲料中添加谷氨酰胺前体物对镜鲤肠道消化酶及Na~+/K~+-ATPase活性的影响

为了研究谷氨酰胺前体物对镜鲤(Cyprinus carpio specularis)肠道消化酶及Na~+/K~+-ATPase活性的影响,分别用谷氨酰胺(Gln)、谷氨酸(Glu)、α-酮戊二酸(AKG)、L-鸟氨酸-α-酮戊二酸(OKG)、L-精氨酸-α-酮戊二酸(AAKG)、α-酮戊二酸钠(2Na-AKG)替代基础饲料中的葡萄糖(添加量为1.5%),配制成6种等氮等能试验饲料,以基础饲料为对照,分别投喂松浦镜鲤(平均体重(40.27±3.96)g),饲养8周后测定镜鲤肠道消化酶及Na~+/K~+-ATPase活性。结果显示:Glu组前肠蛋白酶活性显著高于对照组;Gln组、Glu组、OKG组和AAKG组中肠蛋白酶活性均显著高于对照组。2Na-AKG组前肠脂肪酶活性显著高于对照组和OKG组;2Na-AKG组中肠脂肪酶活性显著高于对照组和Gln组。2Na-AKG组前肠淀粉酶活性均显著高于对照组和Gln组。Gln组和Glu组前肠Na~+/K~+-ATPase活性均显著高于对照组;不同处理组中肠Na~+/K~+-ATPase活性均显著低于对照组;Glu组、AKG组和OKG组后肠Na~+/K~+-ATPase活性均显著高于对照组,Gln组、AAKG组和2NaAKG组后肠Na~+/K~+-ATPase活性则均显著低于对照组。研究表明,饲料中添加Gln、Glu、OKG和AAKG可显著提高鱼体肠道的蛋白酶活性,添加2Na-AKG可显著提高鱼体肠道的淀粉酶和脂肪酶活性。     

福瑞鲤选育家系不同养殖阶段的生长差异分析

为了进一步观察最佳线性无偏预测(best linear unbiased prediction,BLUP)家系选育方法在福瑞鲤(Cyprinus carpio)继代选育中的潜力,该研究测量了继续选育第2代家系群体不同养殖阶段的体质量和形态性状。结果表明,生长快速家系群福瑞鲤早期(4月龄)生长速度较慢,到后期则生长加快,其体质量增长表现出明显的优势。在体型方面,随着养殖时间的延长,福瑞鲤各选育家系群的体厚/体长增加,体高/体长降低,逐渐呈现其体型修长的特征;同时2个越冬期的成活率均达到了94%以上。结果表明通过BLUP家系选育对福瑞鲤长期选育是可行的。在此基础上,通过主成分分析发现,福瑞鲤生长性状第一主成分是体质量;对不同生长时期的体质量进行相关性分析,发现9月龄、14月龄、21月龄鱼的体质量与24月龄的相关系数均达到极显著水平(P0.01),分别为0.851、0.897和0.957。因此,在福瑞鲤继续选育过程中,进行早期个体选择值得尝试。     

Koi herpesvirus and carp edema virus threaten common carp aquaculture in Croatia

Common carp (Cyprinus carpio) is a very important fish species for warm-water aquaculture in Croatia. All Croatian carp farms are subjected to a surveillance programme for the presence of koi herpesvirus (KHV), causing a deadly disease called koi herpesvirus disease (KHVD). However, there is no surveillance for other viral pathogens of importance like carp edema virus (CEV), a causative agent of koi sleepy disease (KSD). During regular testing within the KHVD surveillance programme, we tested samples for CEV simultaneously. The screening indicated possible outbreaks of KHVD and KSD. During 2016, KHVD broke out in an isolated area and soon thereafter a KHV eradication programme was successfully performed. However, during 2018 and 2019, two additional mortality events occurred in lakes in the southern part of Croatia during the spring. Samples from both events tested positive for CEV. An epidemiological investigation confirmed the introduction of infected carps from an infected farm to one of the lakes. To prevent the spreading of CEV into open waters, it is of utmost importance to introduce CEV testing before fish movement or to perform regular testing of all carp farms in the country to determine CEV prevalence for the purpose of implementation of control measures.     

Effects of juniper berry oil on growth performance and blood parameters in common carp (Cyprinus carpio)

In this study the effects of commercial juniper berry oil (JBO) as a feed additive in diets for common carp (Cyprinus carpio) was investigated in terms of growth performance, feed utilization and blood parameters. The experimental diets were prepared to contain JBO at rate of 0 (JBO‐0), 5 (JBO‐5) and 10 (JBO‐10) ml/kg. Common carps (3.07 ± 0.15 g) were fed with test diets for a period of 60 days in 40‐L aquariums of triplicate groups. The feeding experiment revealed that JBO groups showed significantly better growth performance and feed utilization compared with the control group (JBO‐0) (p < 0.05). No significant effect was observed on hemoglobin amount, haematocrit ratio and consequential erythrocyte indices (p > 0.05). In the JBO groups, serum cholesterol, triglyceride, glutamic–pyruvic transaminase and alkaline phosphatase levels decreased significantly (p < 0.05). In contrast, the total protein level showed a significant increase, while glucose, albumin and lactate dehydrogenase levels did not present any significant variation (p > 0.05). Therefore, dietary addition of 5 ml/kg JBO promoted fish growth and positively influenced the blood parameters in common carps.     

Effects of antimicrobial peptides on growth,morphology of foregut villi and related genes mRNA expression in the common carp (Cyprinus carpio)

A 60‐day feeding trial was conducted to examine the effects of different levels (0, 100, 200, 400 and 600 mg/kg) of antimicrobial peptides on growth, protease activity of foregut, the morphology of foregut villi and related genes mRNA expression level in the common carp (Cyprinus carpio). The results showed that the feed of antimicrobial peptides promote common carp growth, and the optimal dosage of antimicrobial peptides is 200–333 mg/kg in the common carp feed. The protease activity of 200 and 400 mg/kg groups were significantly higher than the control and other groups (p < 0.05). The foregut villus height with 100, 200 and 400 mg/kg antimicrobial peptide groups were significantly higher than control group (p < 0.05). The crypt depth of 200 and 400 mg/kg antimicrobial peptide groups were significantly lower than control group (p < 0.05). The ratio of villus height and crypt depth of 100, 200 and 400 mg/kg antimicrobial peptide groups were significantly higher than control group (p < 0.05). The ratio with 600 mg/kg group was significantly lower than the control group (p < 0.05). The IGF‐I gene expression level of 200 mg/kg and 400 mg/kg groups were significantly higher than the control group and 600 mg/kg group (p < 0.05). The IL‐1β gene expression level of 100 mg/kg and 200 mg/kg groups were significantly higher than the control group (p < 0.05). These results indicated up‐regulation of growth and immune related genes in antimicrobial peptides fed common carp. Correlation analysis showed that IGF‐I mRNA and IL‐1β mRNA were positively correlated with SGR. IL‐1β mRNA and FCR were significantly negative correlated. It indicated that growth and immune gene common regulated the growth of the carp under antimicrobial peptides intervention. In conclusion, antimicrobial peptides can improve growth and related genes mRNA expression in the common carp. Further studies using molecular biological technique or immunologic methods are required to conclude that antimicrobial peptides are beneficial in common carp.     

鲤鱼肠道中4种细菌的分离与生化鉴定

为研究健康鲤鱼肠道菌群组成情况,为其饲料添加剂和水质改良剂的开发利用提供基础资料,试验对鲤鱼肠道中的细菌进行分离培养,通过形态特征观察、生化试验进行鉴定.结果:在鲤鱼肠道中分离出4种细菌,分别为:金黄色葡萄球菌(Staphyloccocus aureus)、沙门氏菌(salmonella)、粪肠球菌(Enterococcus faecalis)、枯草芽孢杆菌(Bacillus subtilis).     

Investigation of the leptin levels in the blood serum of Cyprinus carpio (Linnaeus, 1758) and Capoeta trutta (Heckel, 1843)

Leptin is a peptide hormone secreted by adipose tissues in the various teleost fish and vertebrates. Leptin has been suggested to have an important role in a range physiological function, including regulation of food intake, reproduction, immune function, energy expenditure, lipid and carbohydrate metabolism. In this study, leptin levels in the blood serum of Cyprinus carpio and Capoeta trutta were determined. Then the results were compared between two species and between sexes of each species. In addition, leptin levels were also compared with the body weight and length of both C. carpio and C. trutta. Leptin level was analysed using available enzyme‐linked immunoassay (ELISA) kit (Rat leptin ELISA kit, catalog no: SK00050‐08). Leptin levels showed no significant difference (p > 0.05) that in relation to between two species and between sexes of each species. It has been shown that not significantly correlated when examined correlations between the leptin level in blood serum and body weight (r = 0.192, p = 0.380) or length (r = 0.102, p = 0.644) of C. carpio. Similarly, the correlations between leptin level in blood serum and body weight (r = 0.021, p = 0.959) or length (r = 0.123, p = 0.595) of C. trutta were also not significant.