Molecular Cloning,Characterization and Expression Profile of Myf5 and Myf6 During Growth and Development in the Seriola lalandi

Myogenic Regulatory Factors(MRFs)is involved in the muscle growth and differentiation.In this study,the cDNA sequence of yellowtail kingfish MRFs genes were cloned by rapid amplification of cDNA ends(RACE)method;then,the character-istics of these genes and the predicted protein sequences were analyzed by bioinformatics methods,the tissue and embryonic stages differential expression pattern were detected by the quantitative real-time PCR.Our results showed that the yellowtail kingfish(YTK)Myf5 cDNA has a full length of 951 bp,encoding 266 amino acids.The yellowtail kingfish Myf6 cDNA has a full length of 1105bp,encoding 250 amino acids.The proteins containα-helix,β-strand,and loops.The Neighbour-joining tree revealed that YTK Myf5 and Myf6 are closely related to Seriola dumerili.The yellowtail kingfish Myf5 and Myf6 gene expressed significantly higher in mus-cle than in other tissues(P<0.05).In addition,Myf5 and Myf6 in muscle was significantly expressed in 400g and 500 g fish but not in 50 g,suggesting that myogenic regulatory factors expression had a great relationship with the fish size.Our results also indicated that Myf5 and Myf6 have different functions during embryonic development,because Myf5 showed highest expression level at the neuroembryo period,but Myf6 had the highest expression level at embryo coverage yolk 70%stage.Myf5 gene showed highest ex-pression at 30 d of age,suggesting it played key roles in myogenic period.However,the Myf6 gene was significantly highly ex-pressed at 60 d,revealing this gene functioned in the later muscle formation period.

Genetic and morphological differences between yellowtail kingfish (Seriola lalandi) from the Bohai Sea, China and the Southern Ocean, Australia

The aquaculture of yellowtail kingfish(Seriola lalandi)has expanded around the globe,including China.Genetic resource of Chinese S.lalandi urgently needs to be assessed for improving production.Here,we collected wild S.lalandi samples from the Bohai Sea,China and evaluated its genetic diversity based on 17,690 nuclear loci.A population from the Southern Ocean,Australia was used for comparison.The analyses showed that the Chinese and Australian S.lalandi formed two completely distinct clusters and there was no genetic introgression from the Australian S.lalandi into the Chinese S.lalandi population.The genetic diversity is slightly lower,but comparable in Chinese versus Australian yellowtail kingfish(Chinese population,expected heterozygosity:0.19,observed heterozygosity:0.19,nucleotide diversity:0.19±0.09;Australian population,expected heterozygosity:0.23,observed heterozygosity:0.22,nucleotide diversity:0.22±0.11).Overall,our results indicated that Chinese S.lalandi could be a potential subject for genetic breeding programs.We also investigated morphological characters and developed molecular markers for population identification.Comparison of meristic characters between the Chinese population and the Australian population revealed that main shape difference were in the number of dorsal spines,dorsal fin rays and the number of upper gill rakers.Geometric morphology based on eight landmarks also revealed significant difference between the two populations including the distance between the tip of snout to origin of pelvic fin and the distance between the tip of snout to origin of pectoral fin.These morphological characters can be used for easy identification of the Chinese S.lalandi.

Early weaning of yellowtail amberjack Seriola lalandi dorsalis (Gill 1863) larvae

Objective: To understand the effect of weaning time on the rearing performance of yellowtail amberjack Seriola lalandi dorsalis in the experimental condition. Methods: The same weaning protocol started on four different days of post hatching (DPH), including 12 DPH (W12), 15 DPH (W15), 18 DPH (W18), and 21 DPH (W21), respectively. Growth, survival, and jaw malformation were used as the assessment criteria to evaluate the impact of weaning time on the performance of yellowtail amberjack larvae. Results: The highest specific growth rate was observed in W21 treatment, and the lowest specific growth rate was found in W12 treatment. The highest survival was achieved in W21 treatment, and the lowest survival was recorded in W12 treatment. With postponing the weaning started time, jaw malformation rate significantly reduced. At the end of this study, the highest malformation rate was observed in W12 treatment, and the malformation rate was not significantly different in W15, W18, and W21 treatment. Conclusions: Base on the results obtained in this study, we suggest that weaning of yellowtail amberjack larvae should be started from 15 DPH.

黄条[鱼师]生长性状全基因组关联分析

利用2b-RAD技术对119尾黄条[鱼师](Seriola lalandi)个体进行测序,共获得黄条[鱼师]SNP分子标记26665个,对黄条[鱼师]个体的体质量和全长这2个重要生长性状进行全基因组关联分析,筛选与体质量和全长性状相关的SNP位点和候选基因。结果显示,黄条[鱼师]体质量性状中共筛选到17个体质量显著关联的SNP位点,找到17个可能的候选基因,全长性状共筛选到12个潜在显著关联位点,找到12个可能的候选基因。利用KEGG数据库对可能的候选基因进行Pathway分析,得知候选基因主要参与了细胞或组织生长发育相关的代谢通路调控过程,可能是影响黄条[鱼师]生长性状密切相关的重要候选SNP位点和功能基因,结果可为今后黄条[鱼师]种质资源可持续利用和育种提供遗传信息资料积累。

3种养殖鱼消化相关酶活性的比较分析

为深入了解鱼的消化生理特性,测定并比较分析了3种鱼[高体(Seriola dumerili)、黄条(Seriola lalandi)、五条(Seriola quinqueradiata)]的消化系统(胃、幽门盲囊、前肠、中肠、后肠和肝脏)中5种消化相关酶(胰蛋白酶、脂肪酶、淀粉酶、碱性磷酸酶和酸性磷酸酶)活性与组织分布特点。结果显示,3种鱼中5种消化相关酶主要分布在幽门盲囊、肝脏和肠道中。3种鱼胃组织中胃蛋白酶活性无差异。幽门盲囊中胰蛋白酶活性:黄条>高体>五条(P<0.05),高体肝脏组织中胰蛋白酶活性显著高于其他2种鱼(P<0.05);胃、中肠、后肠组织中α-淀粉酶活性:五条>黄条>高体(P<0.05),幽门盲囊、前肠组织中α-淀粉酶活性:黄条>五条>高体(P<0.05);胃、幽门盲囊组织中脂肪酶活性:黄条>五条>高体(P<0.05),前肠、后肠、肝脏中脂肪酶活性:五条>黄条>高体(P<0.05);3种鱼的酸、碱性磷酸酶活性组织分布趋势基本一致,其中,黄条幽门盲囊组织中酸、碱性磷酸酶活性最高(P<0.05)。研究表明,3种鱼消化相关酶活性的组织分布特点基本一致,幽门盲囊是5种酶作用的主要靶器官,除胰蛋白酶外,高体其他4种酶活性均显著低于其他2种鱼,黄条幽门盲囊和肠道的5种酶活性显著偏高。结果可为揭示属鱼类的消化生理特性、研制适宜属鱼类消化特点和种特异性生长的高效专用配合饲料提供理论依据。

酵母发酵黄鰤鱼鱼卵的工艺探究及其风味成分分析

为了探究酵母发酵对黄鰤鱼鱼卵脱腥增香的影响,本文先研究了黄鰤鱼鱼卵营养价值,后采用高糖型高活性干酵母对其进行发酵脱腥处理,以感官评分、pH和总酸含量为指标,确定酵母粉接种量、蔗糖添加量、发酵时间和发酵温度等发酵参数。以新鲜鱼卵和未发酵鱼卵作对照,分析发酵后鱼卵样品感官品质、游离氨基酸和挥发性风味化合物的变化。结果表明,黄鰤鱼鱼卵富含多不饱和脂肪酸及锌和硒元素,营养价值较高。在酵母接种量为1.5%,蔗糖添加量为5%,发酵时间为1.5 h,发酵温度为28℃时,黄鰤鱼鱼卵的鱼腥味最低、发酵香味最浓郁、整体风味协调性最好。黄鰤鱼鱼卵中甜味和鲜味氨基酸的含量显著上升(P<0.05),且TAV值总和大于苦味氨基酸,表明酵母发酵掩盖了鱼卵本身的苦味。三种鱼卵样品中共检出81种挥发性化合物,经酵母发酵后,鱼卵中挥发性化合物种类和含量均增加。新鲜鱼卵和未发酵鱼卵中的主要挥发性化合物是庚醛、壬醛、(E,E)-2,4-庚二烯醛等醛类物质,并且腥味物质(1-辛烯-3-醇、(E,E)-2,4-庚二烯醛等)的相对含量较高。酵母发酵鱼卵的主要挥发性化合物是辛酸乙酯和癸酸乙酯等酯类物质,而腥味物质相对含量显著降低(P<0.05)。根据相对气味活度值(relative odor activity values,ROAV值),酵母发酵鱼卵中的关键性风味物质为(E,Z)-2,6-壬二烯醛、(E,E)-2,4-癸二烯醛、苯乙醇、1-辛烯-3-醇和3-甲硫基丙醇,代表鱼腥味的关键性风味物质1-辛烯-3-醇的ROAV值明显下降,新增苯乙醇和3-甲硫基丙醇两种风味成分,为发酵鱼卵提供了玫瑰香味、甜味和肉香味等。总之,酵母发酵有效改善了黄鰤鱼鱼卵的异味,并产生了怡人的发酵风味。

工厂化养殖密度对黄条鰤生长和生理特性的影响

养殖密度是水产养殖管理中一项非常重要的参数,适宜的养殖密度能够降低养殖动物的应激胁迫水平,促进其健康、快速生长。为探究黄条鰤(Seriola lalandi)在陆基工厂化养殖条件下的最适密度,本研究对1龄黄条鰤[(565.83±70.22)g]开展为期60 d的养殖实验,共设置10尾/m^(3)(低密度组)、20尾/m^(3)(中密度组)和30尾/m^(3)(高密度组)3个密度组。实验过程中测量并计算包括增重率、特定生长率、肥满度和肝体指数在内的生长指标,并检测血液生理、血清生化、肝脏和肾脏组织的非特异性免疫酶活性等指标。结果表明,中、高密度组黄条鰤的增重率、特定生长率在第60天时均显著低于低密度组对应的数值(P<0.05);在3个密度组中,低密度组的特定生长率在60 d时显著高于30 d的数值(P<0.05),中密度组的特定生长率在60 d与30 d之间差异不显著(P>0.05),高密度组的特定生长率在60 d时低于30 d的数值,说明高密度养殖对黄条鰤的生长产生了的胁迫。整个实验过程中,血清中肾上腺素和皮质醇等的含量在30 d和60 d时均随养殖密度的增加而显著升高(P<0.05),生长激素和类胰岛素生长因子Ⅰ的含量呈相反趋势;肝脏和肾脏中超氧化物歧化酶、溶菌酶、谷丙转氨酶、谷草转氨酶、酸性磷酸酶、碱性磷酸酶和丙酮酸激酶的活性在30 d和60 d时整体呈现随养殖密度的增加而显著升高的趋势(P<0.05),说明高密度养殖对黄条鰤的生理造成了胁迫。由此可见,从生长、生理和生产实践角度综合评价,中密度(20尾/m^(3))是1龄黄条鰤工厂化养殖的适宜密度,相关研究结果将为黄条鰤工厂化养殖技术进一步完善提供参考。

营养代谢过程中黄条鰤幼鱼消化道菌群的演变趋势

为认识消化道菌群结构在宿主营养代谢过程中的变化规律,并探讨饵料菌群对其的影响,采用16S rDNA高通量测序技术,对黄条鰤(Seriola lalandi)幼鱼一个完整摄食周期内的消化道菌群结构特征进行研究,并解析其与饵料菌群的相关性。结果显示,乳杆菌属(Lactobacillus)、假单胞菌属(Pseudomonas)、不动杆菌属(Acinetobacter)、鞘氨醇单胞菌属(Sphingomonas)、拟杆菌属(Bacteroides)、气单胞菌属(Aeromonas)、弧菌属(Vibrio)和Faecalibacterium等是黄条鰤胃、幽门盲囊和肠道的共有优势定植菌群。结合营养代谢过程中优势菌属变化规律,将乳杆菌属、肠弧菌属(Enterovibrio)、双歧杆菌属(Bifidobacterium)、假单胞菌属、不动杆菌属、芽孢杆菌属(Bacillus)、Escherichia-Shigella、类芽孢杆菌属(Paenibacillus)、鞘氨醇单胞菌属、拟杆菌属、甲基单胞菌属(Methylomonas)、链霉菌属(Streptomyces)、气单胞菌属、弧菌属、普氏菌属(Prevotella)、芽孢乳杆菌属(Sporolactobacillus)、发光杆菌属(Photobacterium)和Faecalibacterium作为本研究黄条鰤幼鱼消化道的核心菌群;其中的乳杆菌属、芽孢杆菌属、双歧杆菌属、芽孢乳杆菌属是水产养殖中常见的潜在益生菌;而假单胞菌属、气单胞菌属、弧菌属和发光杆菌属中的部分菌株被视为潜在病原菌;研究结果揭示了潜在益生菌与致病菌始终以动态平衡的状态定植于健康幼鱼的消化道内,并参与宿主生理活动,从微生态角度保障宿主健康。通过优势菌群结构演变趋势分析发现,饵料菌群对营养代谢过程消化道菌群相对丰度的影响较大,进一步揭示了饵料微生物安全的重要性。

两种养殖模式下黄条鰤幼鱼消化道菌群对生长的微生态调控作用

探究了工厂化、网箱养殖模式对黄条鰤(Seriola lalandi)幼鱼生长性能及消化道菌群的影响,通过16SrRNA高通量测序和生物信息学方法,分析了两种养殖模式下黄条鰤幼鱼消化道(胃、幽门盲囊、肠道)、饵料及养殖水中的菌群结构特征及其互作关系。结果显示,本实验条件下,网箱养殖黄条鰤幼鱼较工厂化养殖鱼生长性能显著提升;在黄条鰤幼鱼消化道菌群方面,门水平上的拟杆菌门(Bacteroidetes)、厚壁菌门(Firmicutes)和属水平上的拟普雷沃氏菌属(Alloprevotella)、拟杆菌属(Bacteroides)在网箱养殖模式中其丰度值高于工厂化养殖模式,其中拟杆菌属仅出现于网箱养殖模式且呈现显著性差异;Beta多样性分析显示消化道菌群更多受到饵料菌群的影响,受水环境影响相对较小。KEGG注释分析表明两种养殖模式的差异菌群中,网箱养殖幼鱼消化道菌群主要参与磷酸转移酶系统(PTS)和NOD样受体信号通路,而工厂化养殖幼鱼为碳水化合物代谢和类胡萝卜素合成通路。本研究表明,环境菌群中,饵料菌群对消化道菌群的影响大于养殖水体菌群;消化道微生物群落通过调整其组成结构从而改变菌群功能通路的方式,积极参与两种养殖模式下黄条鰤幼鱼生长机能差异的调控。因此,网箱养殖鱼表现出更快速的生长性能可能是由于机体内的菌群产生了更多的短链脂肪酸并诱导IGF-1等生长相关功能基因的表达,从而促进机体的营养吸收和生长。本研究预期结果将为黄条鰤专用配合饲料的研制和健康养殖技术开发提供微生态理论支撑。