镜鲤多家系体长和体质量QTL定位分析

为了克服单个家系数量性状位点(QTL)检测效率低、假阳性高等缺点,实验利用250对微卫星(SSR)标记对镜鲤8个全同胞家系的522尾子代进行基因组扫描,采用半同胞家系的分析策略对镜鲤体长(SL)和体质量(BW)性状进行QTL分析。结果显示,基于父系的QTL分析,共检测到4个QTL区间,其中,3个体长的QTL中,1个为95%基因组水平(genome-wide)显著性,位于LG24,可解释表型变异率为20.3%;其余2个均为95%染色体水平(chromosome-wide)显著性,分别位于LG6和LG30,可解释表型变异率分别为11.9%和11.6%。1个体质量的QTL达到99%基因组水平,位于LG24,可解释表型变异率达到38.3%,且与体长QTL区间重叠。基于母系的QTL分析,共检测到8个QTL区间,其中,5个体长的QTL中,1个为99%染色体水平,位于LG8,可解释表型变异率为16.6%;其余4个均为95%染色体水平,分别位于LG24、LG30、LG31和LG45,可解释表型变异率为9.6%~14.2%,且位于LG24和LG30上的QTL为父母本共有;3个体质量的QTL均与体长QTL区间重叠,1个为95%染色体水平,位于LG24,其余2个均为99%染色体水平,位于LG30和LG45,可解释表型变异率分别为14.1%和13.6%。进一步分析发现,位于LG24上的体长和体质量QTL区间重叠且均为父母本共有,体质量的3个QTL均与体长QTL存在重叠区域且呈现成簇分布的特点。本研究结果不仅可以为鲤分子育种提供更可靠的标记,而且为家系和品种间QTL变异规律的探索提供基础数据。     

镜鲤头长及头长体长比性状的主效QTL挖掘

为挖掘镜鲤头长及头长体长比性状的主效QTL区间,实验利用368个SSR、336个SNP标记对镜鲤良种后代杂交F1群体的68个个体进行基因型检测,运用JoinMap 4.0软件包构建遗传连锁图谱。该图谱包含535个分子标记并被分配到50个连锁群上,覆盖基因组总长度为2 244.66 cM,标记间平均距离为4.63 cM。利用MapQTL 5.0(interval mapping,IM)区间作图法进行QTL检测。结果显示,共得到2个与头长相关的QTL区间,分别分布在LG21和LG42,可解释型变异分别为28.2%、32.6%;6个与头长体长比性状相关的QTL位于LG8、LG15、LG18、LG21、LG39、LG40,可解释表型变异范围是16.4%~49.3%。全部QTL区间中贡献率大于20%的主效QTL有7个,HL-21和HL-42是头长性状的主效区间;HBR-8、HBR-15、HBR-21、HBR-39和HBR-40是头长体长比性状的主效QTL区间。利用SPSS的一般线性模型(GLM)针对另一群体进行验证,结果表明HLJ692与镜鲤头长体长比显著相关。     

Betanin attenuates carbon tetrachloride (CCl4)-induced liver injury in common carp (Cyprinus carpio L.)

This study investigates the protective effect of betanin against liver injury induced by carbon tetrachloride (CCl₄) in common carp (Cyprinus carpio L.). The fish were treated with 1, 2, and 4 % betanin in fodder throughout the experiment. After 20 days of treatment, the fish were intraperitoneally injected with 20 % (v/v in peanut oil) CCl₄ at a volume of 0.5 mL/kg body weight. The fish were killed 3 days after CCl₄ intoxication, and then, histological and biochemical assays were performed. Results showed that CCl₄-induced liver CYP2E1 activity, oxidative stress, and injury, as indicated by the depleted glycogen storage, increased serum aspartate aminotransferase (AST)/alanine aminotransferase (ALT) activities and liver histological damage. Compared with the CCl₄ control group, the betanin-treated groups exhibited reduced CYP2E1 activity, decreased malondialdehyde level, increased liver antioxidative capacity (increased glutathione level and superoxide dismutase and catalase activities), increased liver glycogen storage, and reduced serum AST/ALT activities, with significant differences in the 2 and 4 % groups (p < 0.05). Histological assay further confirmed the protective effect of betanin. In conclusion, betanin attenuates CCl₄-induced liver damage in common carp. Moreover, the inhibition of CYP2E1 activity and oxidative stress may have significant roles in the protective effect of betanin.     

镜鲤体质量和体长的QTL定位研究

以镜鲤(Cyprinus carpio L.)全同胞家系为材料,用940对微卫星(SSR)标记进行基因组扫描,采用半同胞家系的分析策略对体质量(BW)和体长(SL)进行QTL定位分析。QTL检测显示:基于父系的QTL分析,共检测到8个QTL区间。5个与体质量相关的QTL区间中,1个QTL为95%基因组水平(genome-wide)显著性,位于LG26连锁群,其他4个QTL均为95%染色体水平(chromosome-wide)显著性;3个与体长相关的QTL区间与体质量的QTL区间重叠,其中,1个QTL为99%基因组水平显著性,其余2个QTL均为95%染色体水平显著性。基于母系的QTL分析,共检测到11个QTL区间。6个与体质量相关的QTL区间中,1个QTL为99%基因组水平显著性,位于LG26,2个QTL为99%染色体水平显著性,其余3个QTL均为95%染色体水平显著性;5个与体长相关的QTL中有4个与体质量QTL区间重叠,其中,1个QTL为99%基因组水平显著性,1个QTL为99%染色体水平显著性,其余3个QTL均为95%显著性染色体水平。结果表明,在LG26上,存在着与体质量和体长都显著相关的QTL区间,且均达到基因组显著性水平,最小置信区间为3 cM。此QTL结果可以应用于鲤鱼分子标记辅助育种。     

Characteristics of the reproduction effectiveness of four Hungarian breeding lines of carp Cyprinus carpio (L.)

The effectiveness of reproduction of four Hungarian breeding lines 7, 8, W, and 0 of carp Cyprinus carpio was investigated. The highest percentage of ovulating females after Ovopel stimulation of ovulation (1/5 + 1 pellet kg^?1 BW of females) was found in line 8 (100 %), in line 0, it was 86.21 %, and in lines 7 and W, the respective values were 73.68 and 76.47 %. It was noted that the breeding line significantly (P ≤ 0.05) determined the weight of the eggs (expressed in grams and percentage of female BW), the fertilization percentage, the percentage of living embryos after 24- and 36-h incubation, the total number of eggs, and the number of live embryos after 36-h incubation. The highest weight of eggs was obtained from females of line 7 (1,083.41 g) and line 8 (981.54 g), while the lowest weight was noted in the case of females of line W (804.94 g). The highest number of eggs was found in line 7 (722,300) and in line 8 (654,400). For these lines, the highest number of live embryos (36 h) was also found (624,400 and 622,200, respectively). Within each line investigated, the regression equations were derived in order to predict the weight of eggs (g), percentage of live embryos, and the number of live embryos after 36-h incubation.     

Parental genetic effects evaluation of growth-related traits of red common carp in China

Reciprocal differences have been observed widely for given traits in fish breeding programs, but maternal and paternal effects and heritable extranuclear genetic effects have often been omitted in the evaluation of genetic variance. In this study, we have applied a mixed genetic model to conduct a complete diallel cross using three varieties of red common carp (Cyprinus carpio L.), namely, C. carpio. var. singuonensis, C. carpio var. wuyuanensis and C. carpio var. color. Parental and direct (additive and dominance) genetic effects for growth-related traits at 8 and 20 months post-hatch were analyzed. At 8 months post-hatch, only significant additive and dominance variances were observed, while maternal and paternal variances were low and non-significant in the traits evaluated: body weight, total length, standard length, pre-dorsal height, pre-dorsal width, caudal peduncle length, and caudal peduncle height. At 20 months post-hatch, with the exception of significant additive and/or dominance variances, maternal variances were significant for the traits of body weight, pre-dorsal height, pre-dorsal width, and caudal peduncle height, and the paternal variance was significant only for total length. The maternal effects in the common carp had greater genetic influence on offspring than the paternal effects. Female C. carpio var. wuyuanensis were more suitable as brooders than males, but both female and male C. carpio var. color can be used as brooders according to breeding programs of improved traits. Cyprinus carpio var. singuonensis was the worst brooder of the three varieties of common carp evaluated.     

Effect of different types of descaling methods on shelf life of air-/vacuum-packaged common carp (<Emphasis Type="Italic">Cyprinus carpio</Emphasis> L.) fillets under refrigerated storage conditions

Microbiological quality, sensory attributes and consumer preferences of common carp (Cyprinus carpio L.) fillets descaled by four different methods under two storage conditions (air packed and vacuum packaged) and refrigerated storage conditions were studied. Farmed common carps (scaly and mirror), of marketable size (2.2 kg, 3 years old), were randomly divided into four experimental groups (n = 10), and filleted and fillets were processed by four descaling methods: without skin, without scales, undercut scales and mirror carp (without any other treatment). Microbiological analyses were determined by total viable counts (TVCs) in logarithm of colony-forming units per gram (log CFU/g), and sensory quality of fillets was classified by odour, flavour, after taste and consistency on storage days 0, 3, 6 and 9. Vacuum packaging conditions affected the growth of microbiota and extended the shelf life of fillets in all experimental groups. Microbial communities grew to between 3.19–3.90, 4.03–6.00 and 6.35–8.28 log CFU/g after 3, 6 and 9 days of storage, respectively, and fillets without skin showed the lowest TVC among all analysed groups throughout storage. Also sensory analyses showed that consistency and odour of carp fillets were influenced by packaging conditions as well as descaling methods. The survey on consumer preferences of carp found out that 58.9 % of customers preferred scaly carp with undercut scales and processed to fillets instead of mirror carp. The results of present study show that different types of descaling methods combined with air/vacuum packaging can significantly prolong the shelf life of carp fillets.     

草鱼生长性状的遗传参数和育种值估计

利用草鱼(Ctenopharyngodon idellus)生长性状选育核心群亲本,采用人工授精方式构建21个全同胞家系,并选用动物模型对16月龄草鱼生长性状进行遗传参数和育种值估计。结果显示,草鱼选育种群的生长性状存在丰富变异。采用约束极大似然法估计方差组分,发现草鱼体重、体长和体高性状的遗传力分别为0.39,0.47,0.21,属于中高遗传力;肥满度性状遗传力为0.11,属于低遗传力;4个性状的共同环境效应值相近且较小,范围为0.07~0.17。采用两性状动物模型分析相关性,发现体重、体长和体高性状间表型和遗传相关系数均达到高度正相关(r=0.88~0.97),而肥满度性状与三者间相关系数接近零,只与体高性状存在一定遗传正相关(r=0.43)。结合各性状遗传变异系数和相对遗传进度,分析表明,以体重为目标性状可便捷有效地改良草鱼生长性能。采用最佳线性无偏估计法预测个体育种值,发现4个性状育种值与表型值的相关系数范围为0.77~0.93。基于单性状育种值和表型值分别进行个体选择,按10%留种率,各性状选留个体相同率为68.75%~81.82%,秩相关系数范围为0.19~0.81,两种选择方式显示出较大差异,且差异大小与性状遗传力成反比例。本研究为草鱼生长性状选择育种提供了理论依据和技术支撑。     

The long-term effect of serotonin on the thermoregulatory behavior in juvenile cyprinidae (Cyprinus carpio and Carassius auratus)

The effect of serotonin after intracerebroventricular (ICV) injections in dosage of 0.3 and 0.15 μg/g of the body weight on the thermoregulatory behavior in juvenile carp Cyprinus carpio L. and goldfish Carassius auratus (L.) has been studied in two experiments of 10- to 11-day duration. It has been found that ICV injection of serotonin in dosage of 0.3 μg/g caused the initial decrease in preferred temperatures (PT) (2–3 days) followed by their further increase (4–8 days after the administration) in carp. ICV injection of serotonin in dosage of 0.15 μg/g caused more durable initial decrease in PT (2–8 days) followed by the increase of once (9–11 days of observation) in goldfish. The values of the ultimate preferred temperature in fish of the experimental group exceeded that in control specimens by 4.1 °C at the first experiment and by 3.1 °C in the second experiment. The data for the first time demonstrated long-term effect of a single ICV injection of serotonin on the thermoregulatory behavior in two closely related species of teleosts.     

Additive, dominance genetic effects for growth-related traits in common carp, Cyprinus carpio L.

Additive, dominance genetic effects were analysed for body weight (BW) and seven morphometric traits from three variants of red common carp, Cyprinus carpio var. singuonensis, C. carpio var. wuyuanensis and C. carpio var. color, based on a diallel cross‐mating design by using the additive–dominance genetic model. The results indicated that at 8 months of age (juvenile stage), the traits of pre‐dorsal height (PDH), pre‐dorsal width (PDW) and caudal peduncle height (CPH) were mainly controlled by additive effects; the traits of BW, total length (TL), standard length (SL), head length (HL) and caudal peduncle length (CPL) were mainly controlled by dominance effects. The narrow‐sense heritabilities of all traits ranged from 0.000 to 0.556; however, the broad‐sense heritabilities ranged from 0.453 to 0.775. At 20 months of age (adult stage), the traits of TL, SL, PDH and CPL were mainly controlled by additive effects, whereas the traits of BW, PDW, HL and CPH were mainly controlled by dominance effects. The narrow‐sense heritabilities of all traits ranged from 0.000 to 0.710; the broad‐sense heritabilities ranged from 0.629 to 0.934. Through the genetic merit prediction from three parents, it was found that the additive and dominance effects of C. carpio var. color could increase the BW and body length in their progeny, but these two genetic effects of C. carpio var. singuonensis and C. carpio var. wuyuanensis could decrease BW in their progeny. The genetic effects of C. carpio var. wuyuanensis could reduce total length, SL and caudal peduncle length, but increase body height in their progeny.     

3个鲤群体杂交后代生长性状的灰色关联及复合杂交后代的体重预测分析

为了更好地了解和利用杂种优势,并在此基础上期望从可能产生的多个复合杂交组合中寻找可能的优良组合。实验通过建立回归模型、方差组分剖分、灰色关联度、比较不同方法的预测效果对建鲤、黄河鲤、黑龙江野鲤3个鲤群体双列杂交F₁代杂种优势的利用进行了分析。结果表明,(1) 未考虑PIT标记和考虑PIT标记时所测性状对体重影响作用不同。结合灰色关联度分析表明,2个时期的体长(体长和标记体长)对体重均有影响;(2) 不同组合、组合内家系间以及初始体重和雌性的互作固定效应显著;(3) 3种不同预测方法的分析表明,组合Hyj,Hjy和JJh可在复合育种时优先考虑。实验结果表明,杂交F₁代体重与初始体重和性别(尤其是雌性)的互作、标记体长对体重的影响要在实际育种中引起足够的重视;复合杂交可提高杂种优势的利用率。     

Modulation of appetite,lipid and glucose metabolism of juvenile grass carp (<Emphasis Type="Italic">Ctenopharyngodon idellus</Emphasis>) by different dietary protein levels

This study was undertaken to explore the systemic metabolic strategies of juvenile grass carp (Ctenopharyngodon idellus) to maintain growth when fed with different dietary protein levels. The optimal growth group and two growing discomfort groups were selected through the basic data, to explain the growth difference from appetite regulation and lipid and glucose metabolism perspective. Three experimental diets were formulated with three dietary protein levels at 200.3, 296.1 and 442.9 g kg^?1, named P1, P2 and P3, respectively. Juvenile grass carp (initial body weight 12.28 ± 0.14 g) were fed with three diets with 3 replications per dietary treatment in an indoor recirculation system for an 8-week feeding trial. Fish fed with diet P2 dietary group showed significantly higher WG, SGR, FI and PER than other groups. Compared with other groups, mRNA expressions of NPY, Y8a and Y8b in fish fed with P2 significantly down-regulated, while the expressions of CCK and CART in fish fed with P3 significantly down-regulated (P < 0.05). With increasing dietary protein levels, G6Pase, GK, PK and PEPCK were all significantly inhibited (P < 0.05). For lipid metabolism, the mRNA expression of ACC in P1 dietary group was significantly higher than P3 dietary group; besides, LPL expression in P3 group was significantly higher than other two groups (P < 0.05). PPARα expression in P2 was significantly lower than other groups (P < 0.05). These results suggested that grass carp fed with P2 (296.1 g kg^?1 protein level) showed highest weight gain, contributed to more balanced nutrient metabolism and appetite regulation. Too high dietary protein (442.9 g kg^?1) should be avoided because it induced lowest PER, body lipid and liver lipid, and inhibited glucose and lipid metabolism in juvenile grass carp.     

Purification and characterization of glucose 6-phosphate dehydrogenase (G6PD) from grass carp (Ctenopharyngodon idella) and inhibition effects of several metal ions on G6PD activity in vitro

Glucose 6-phosphate dehydrogenase (G6PD) is a key enzyme catalyzing the first step of the pentose phosphate pathway which generates NADPH for anabolic pathways and protection systems in various organisms, including fish. In the present study, G6PD was purified from grass carp (Ctenopharyngodon idella) hepatopancreas using the methods of 2′,5′-ADP-Sepharose 4B affinity chromatography followed by DEAE Sepharose Fast Flow ion exchange chromatography. The characterization of G6PD and inhibition effects of several metal ions on G6PD activity in vitro were also determined. Grass carp hepatopancreas G6PD, with a specific activity of 18 U/mg protein, was purified 1,066-fold with a yield of 19.5 % and Mr of 71.85 kDa. The enzyme had a temperature optimum of 42 °C, pH optimum of 7.5 and 9.0. The K _m values for G6-P and NADP⁺ were determined to be 0.026, 0.0068 mM, respectively. The V _max values for G6-P and NADP⁺ were 2.20 and 2.27 μM min^?1 mg protein^?1, respectively. The catalytic efficiency for G6-P and NADP as the substrates was 0.085 and 0.334 × 10^?6 min^?1 mg protein^?1, respectively. Inhibition effects of metal ions on the purified G6PD activity indicated that IC₅₀ values of Zn⁺², Mn⁺², Al⁺³, Cu⁺², and Cd⁺² were 0.42, 0.54, 0.94, 1.20, and 4.17 mM, respectively. The Ki constants of Zn⁺², Al⁺³, Cu⁺², and Cd⁺² were 0.52, 1.12, 0.26, and 4.8 mM, respectively. Zn⁺², Al⁺³, and Cd⁺² showed competitive inhibition, while Cu⁺² inhibited the G6PD in a noncompetitive inhibition manner. Our study provided important information about the control of the grass carp liver PPP, the biosynthesis of several important related biomolecules, and the status of detoxification systems in grass carp liver in relation to metabolism.     

Supplementation of microbial levan in the diet of Cyprinus carpio fry (Linnaeus, 1758) exposed to sublethal toxicity of fipronil: effect on growth and metabolic responses

A 60-day feeding trial was conducted to study the effect of dietary microbial levan on growth performance and metabolic responses of Cyprinus carpio fry exposed to sublethal dose (1/10th LC₅₀) of fipronil [(±)-5-amino-1-(2,6-dichloro-α,α,α-trifluoro-p-tolyl)-4-trifluoromethylsulfinylpyrazole-3-carbonitrile]. Two hundred and twenty five fry were randomly distributed in five treatments in triplicates. Four purified diets were prepared with graded levels of microbial levan. Five different treatment groups were levan control L₀P₀ (basal feed + 0 % levan without exposure to pesticide); pesticide control L₀P₁ (basal feed + 0 % levan with exposure to pesticide); L_0.25P₁ (basal feed + 0.25 % levan with exposure to pesticide); L_0.50P₁ (basal feed + 0.50 % levan with exposure to pesticide); and L_0.75P₁ (basal feed + 0.75 % levan with exposure to pesticide). Weight gain% and specific growth rate were significantly higher (p < 0.05) in levan fed groups compared to their non-levan fed counterpart. Highest (p < 0.05) content of ascorbic acid in muscle, liver and brain tissues was observed with higher level of dietary levan. Glucose-6-phosphate dehydrogenase activity decreased with the increasing level of dietary levan in the liver and muscle. Aspartate aminotransferase activity exhibited a second order polynomial relationship with the dietary levan, both in liver (Y = ?1.001x ² + 5.366x + 5.812, r ² = 0.887) and muscle (Y = ?0.566x ² + 2.833x + 6.506, r ² = 0.858) while alanine aminotransferase activity showed third order polynomial relationship both in liver (Y = 1.195x ³ ? 12.30x ² + 35.23x + 9.874, r ² = 0.879) and muscle (Y = 0.527x ³ ? 8.429x ² + 31.80x + 8.718, r ² = 0.990). Highest (p < 0.05) superoxide dismutase activity in gill was observed in the group fed with 0.75 % levan supplemented diet. Overall results indicated that dietary microbial levan at 0.75 % in C. carpio fry ameliorated the negative effects of fipronil and augmented the growth.     

草鱼生长相关的微卫星标记在选育群体中的验证

生长性状是水产动物遗传育种中的重要经济性状,利用与性状相关的分子标记与育种相结合的手段,可以大大加速育种进程。在对草鱼生长性状的前期研究中,采用数量性状位点(QTL)定位的方法,在1号连锁群中发现了2个与生长相关的QTL。在此基础上,实验利用这2个QTL侧翼的2对微卫星标记(CID391_2、CID1512、CID973_1和CID254_1),对长江草鱼选育群体的480个个体进行分析,以期基于草鱼QTL定位结果,对草鱼生长相关的微卫星标记在选育群体中进行验证。结果显示:(1)4个微卫星标记在该群体中均具有高度多态性,其中各位点观测等位基因数(N_a)为12～23个,有效等位基因数(N_e)为4～12个,观测杂合度(H_o)为0.607～0.904,期望杂合度(H_e)为0.751～0.902;(2)利用方差分析及多重比较对4个多态性的微卫星标记与选育草鱼群体的生长性状(体质量和体长)进行关联分析,发现CID391_2在雌性个体中,各基因型与体质量和体长之间均无显著差异;而在雄性个体中,各基因型与体质量和体长之间差异显著。CID1512、CID973_1和CID254_1在雌性或雄性个体中,各基因型与体质量和体长之间均具有显著差异。研究表明,对草鱼生长相关的微卫星标记在选育群体中的验证结果,为进一步开展草鱼生长性状QTL定位研究和基于QTL结果的分子标记辅助育种(MAS)实践奠定理论基础。     

Characterization and expression analysis of two distinct neuropeptide Ya paralogues in Jian carp (Cyprinus carpio var. Jian)

Two distinct neuropeptide Ya paralogues (jlNPYa1 and jlNPYa2) were cloned and characterized in Jian carp (Cyprinus carpio var. Jian), with a highly conserved organization encoded by four exons and three introns. The cDNAs for jlNPYa1 and jlNPYa2 were 693 and 730 bp in size, respectively. jlNPYa1 and jlNPYa2 both encoded a 96-amino acid protein, which shared 97.9 % identity. Phylogenetic tree showed that it has two NPYa genes, called jlNPYa1 and jlNPYa2, that presumably resulted from the tetraploidization event in the carp lineage. Analysis of expression profiles of jlNPYa1 and jlNPYa2 showed that the two NPY genes had a broad tissue distribution but expressed primarily in the forebrain, hypothalamus, testis and liver. The expression pattern was different in juvenile and adult (female and male) Jian carp. In juvenile, the highest expression level of jlNPYa1 and jlNPYa2 was detected in the testis. In adult, it was detected in the forebrain. In female hypothalamus, the expression level of jlNPYa1 was significantly higher than that of jlNPYa2. However, the opposite was true in male hypothalamus. The differing distribution patterns of the two NPY genes suggested that jlNPYa1 and jlNPYa2 might play different roles in Jian carp.     

长牡蛎出肉率与壳形性状的 QTL 定位分析

本研究以长牡蛎(Crassostrea gigas)F1全同胞家系为作图群体,在已构建的基于120个微卫星和66个SNP标记的长牡蛎性别平均连锁图谱上,利用PROC QTL 2.0软件对出肉率和壳形(壳宽和壳深)性状进行QTL定位分析。结果表明,共检测到13个相关的QTL,分布在3个连锁群上;其中,与出肉率相关的4个QTL定位在1号和3号连锁群上(LG1和LG3),表型解释率为0.25%~47.53%;与壳宽相关的3个QTL定位在10号连锁群上(LG10),表型解释率为0.71%~45.39%;与壳深相关的6个QTL也定位在LG10,表型解释率为3.37%~24.78%。根据QTL连锁群分析和性状相关性分析结果可以推测,出肉率与糖原含量性状以及壳宽与壳深性状分别具有相近的遗传特征,利用与相关性状共同关联的分子标记可以同时对出肉率与糖原含量性状、壳宽与壳深性状进行遗传改良。本研究结果为今后长牡蛎相关性状候选基因克隆和分子标记辅助育种提供了参考。     

Cryopreservation of scaly carp (Cyprinus carpio) sperm: effect of different cryoprotectant concentrations on post-thaw motility, fertilization and hatching success of embryos

The aim of the present study was to determine the effect of various cryoprotectants on post-thaw sperm quality and fertilizing capacity of cryopreserved scaly carp (Cyprinus carpio) semen. The present study focused on freezing of scaly carp sperm utilizing a practical and inexpensive protocol for aquaculture. Semen was diluted with Kurokura’s extender composing 3.6 g/l NaCl, 10 g/l KCl, 0.22 g/l CaCl₂, 0.08 g/l MgCl₂ and 0.2 g/l NaHCO₃. The extender contained three different cryoprotectants (DMSO, DMA and egg yolk) at ratios of 5, 10 and 15 %. Semen was placed into 0.25-ml straws and exposed to liquid nitrogen vapor (?120 °C) using an insulated box with an adjustable tray for 10 min and then plunged into liquid nitrogen (?196 °C) tank. The thawing process was performed in a water bath at 40 °C for 10 s. The results indicated that type of cryoprotectants and their concentrations are rather effective in scaly carp sperm cryopreservation on post-thaw sperm quality, while they are very important in order to obtain high fertilization rates. The highest fertilization rate was determined as 96.4 ± 0.15 % with 15 % egg yolk, while the highest hatching rate was determined as 99.3 ± 0.80 with 15 % DMA. In conclusion, the applied cryopreservation method for scaly carp sperm is suitable to fertilize high amounts of eggs.     

Depletion of stored nutrients during fasting in Nile tilapia (Oreochromis niloticus) juveniles

We evaluated growth performance and metabolic responses in Nile tilapia (Oreochromic niloticus) juveniles (30.2 ± 0.9 g) subjected to 1 (F1), 2 (F2), or 3 weeks (F3) of fasting and then refed for 10 weeks (10WR) compared to controls (FC), which were fed for the full 13-week trial. Weight gain and specific growth rate (SGR) during fasting were lower in all treatments compared to the FC. However, during refeeding, feed intake/body mass and SGR increased in F1, F2, and F3, inducing partial compensatory growth. The hepatosomatic index (HSI), visceral fat index (VFI), liver glycogen (LG), and carcass lipid levels dropped in all fasted fish compared to FC (P < 0.05), showing a depletion of stored nutrients such as fat and LG. Along with LG, fat reserves were mobilized during fasting to maintain basal metabolism and survival, but these energy constituents returned to control levels at 10WR, at which time HSI was higher in all refed fish compared to FC. Additionally, the variables VFI, LG, and lipid in carcass increased in all refed fish, equaling those of FC at 10WR. The results showed that, in contrast with other protocols that used smaller tilapia juveniles, the feeding strategies utilized for Nile tilapia juveniles in this study (1 to 3 weeks of fasting and 10WR) were able to induce only partial compensatory growth. It can be concluded that in situations that require complete food restriction in juvenile Nile tilapia (30 g), an acceptable strategy is to limit the period of fasting to 1 week or less to minimize losses and to achieve partial compensatory growth.