刀鲚嗅觉受体基因MOR-51I2克隆、序列分析及组织表达

为研究刀鲚的嗅觉受体（Olfactory receptor,OR）是否参与其生殖洄游过程,利用基因组步移技术,从洄游型刀鲚（Coilia nasus）中克隆出嗅觉受体基因MOR-51I2的基因序列全长。该基因为单外显子结构,编码区长为999 bp。在3'UTR区域具有一段微卫星序列,以（AC）n为重复单位,并夹有若干T或G碱基,且在不同生态型间具有明显长度差异。MOR-51I2基因所编码的蛋白具有7次疏水性α-螺旋的跨膜结构,为G-蛋白偶联受体。MOR-51I2基因与已报道的其他鱼类的OR基因所编码的氨基酸序列的同源性在51%以上,其中与大西洋鲱（Clupea harengus）的OR51I2-like基因的同源性高达83%。经qRT-PCR分析显示,在定居型刀鲚中,MOR-51I2基因主要在嗅囊和性腺中表达,在肝脏、鳃、肌肉微弱表达,在心脏和眼睛中几乎不表达。其中,雌性嗅囊中的表达量约是雄性嗅囊中的2倍,是精巢和卵巢中的80-100倍。在洄游型刀鲚中,该基因在雄性嗅囊的表达量约是雌性嗅囊中的6倍。MOR-51I2基因在洄游型刀鲚的雌性嗅囊中的表达量约是定居型刀鲚的雌性嗅囊中的1/5,而在洄游型刀鲚的雄性嗅囊中的表达量却是定居型刀鲚的雄性嗅囊中的3倍。这些结果表明,MOR-51I2基因不但参与刀鲚的嗅觉功能,而且可能参与了刀鲚的性腺发育及生殖洄游过程,同时也可能与其生态型的分化相关。     

Mitochondrial DNA diversity of Coilia mystus (Clupeiformes: Engraulidae) in three Chinese estuaries

We used sequences of mitochondrial cytb and 16SrRNA gene segments in order to clarify the genetic diversity and population structure in three Chinese estuary populations of Coilia mystus: 21 individuals from ChangJiang River (Yangtze River) estuary, 22 from MinJiang River estuary, and 22 from ZhuJiang River (Pearl River) estuary (65 individuals total). We obtained 607 base pairs of consensus cytb sequence. Thirty four distinct haplotypes were detected among the 65 cytb sequences. The indexes of nucleotide diversity (π) in these three populations were ChangJiang 0.533%, MinJiang 1.135%, and ZhuJiang 0.268%. MinJiang is the largest of the three populations. Genetic distances within the populations were between 0.3 and 1.2%, and 0.8 to 10.8% among populations. The largest genetic distance was 10.8% between the ChangJiang and ZhuJiang populations, and the smallest was 0.8% between MinJiang and ZhuJiang populations. Analysis of molecular variance (AMOVA) analysis revealed that variation among populations accounts for 90.25% of total variation, suggesting that this is the main source of total variance. We obtained 470 base pairs of consensus sequence of 16SrRNA. We detected 19 distinct haplotypes among the 65 sequences. The indexes of nucleotide diversity (π) in these three populations were ChangJiang 0.108%, MinJiang 0.843%, and ZhuJiang 0.097%. MinJiang is also the largest among these three populations. Genetic distances were between 0.1 and 0.9% within populations and 0.5 to 1.9% between populations. The largest genetic distance was the 1.9% between the ChangJiang and MinJiang populations, and the smallest was 0.5% between the MinJiang and the ZhuJiang populations. AMOVA analysis disclosed that variation among populations accounts for 74.61% of total variation, suggesting that this is the main source of total variation. The results of this study suggest that the three Coilia mystus populations, especially the most isolated Changjiang population, have developed significant genetic structure.     

滴滴涕对太湖经济鱼类危害的生态风险

选取滴滴涕(diehloro-diphenyl-trichloro-ethane,DDT)作为太湖持久性有机氯污染的代表性污染物,以大银鱼、陈氏短吻银鱼和刀鲚为研究对象,建立太湖主要经济鱼类食物网模型,并结合DDT的生物化学特性以及蒙特卡罗(Monte Carlo)不确定性分析方法,应用食物网模型研究DDT在食物网主要经济鱼类中的迁移分布特性,分析由此导致的生态风险.结果表明:大银鱼DDT累积量为0～0.329 mg·kg-1,平均值为0.039 mg·kg-1;陈氏短吻银鱼DDT累积量为0-0.188 mg·kg-1,平均值为0.022 mg·kg-1;刀鲚DDT累积量为0-0.575 mg·kg-1,平均值为0.067 mg·kg-1;以脂溶性为代表的污染物累积性质是太湖经济鱼类富集DDT的主要控制因素;生态风险总体状况为:刀鲚＞大银鱼＞陈氏短吻银鱼.     

饥饿胁迫对刀鲚形体、体成分及血液生化指标的影响

以室内养殖刀鲚为试验对象,研究20天的短期饥饿对其形体、体成分和血液生化指标的影响,实验组分别在第0、2、5、10、15和20天取样。结果表明,脏体比和肝体比在饥饿的第2天即显著下降(P<0.05),肥满度和体质量在20天的饥饿期内呈下降趋势,但变化不显著(P＞0.05)。刀鲚肌肉粗脂肪在第5天显著下降(P<0.05),下降5.99%,而粗蛋白含量在第15天时才显著降低(P<0.05),水分在整个饥饿期间总体呈上升趋势,第10天显著上升(P<0.05),粗灰分含量在饥饿期间变化不显著(P>0.05)。血清总蛋白、球蛋白、胆固醇和皮质醇随着饥饿时间的延长呈现先升高后降低的趋势,而血清甘油三酯和血糖总体呈先急速下降并维持一定水平,其中甘油三酯在饥饿至第2天显著下降(P<0.05),血糖浓度在第5天显著下降(P<0.05)。表明短期饥饿胁迫使刀鲚形体发生一定的变化,随着饥饿时间的延长,刀鲚首先先动用体内储存的脂肪来满足能量供应,再动用蛋白质来维持体内的正常代谢,血液生化指标也发生与饥饿相适应的变化。     

基于矢耳石形态特征的中国鲚属鱼类种类识别

分析了中国鲚属鱼类七丝鲚、凤鲚、刀鲚和短颌鲚共4种205尾2龄鱼矢耳石的32个形态特征。对9个可量性状的主成分分析表明,反映矢耳石体积和基叶大小的第1主成分,以及与反映翼叶大小的第2主成分共同解释了总变异的91.2%,是种类判别的主要依据。对10个比例性状的逐步判别显示,4个种的平均正判率达95.6%,但交互验证结果却显示,刀鲚与短颌鲚间存在着20.1%的误判率,表现出与传统的依据外部形态分类和线粒体DNA控制区全序列分析的相似结果。这表明,短颌鲚并非有效种,而是刀鲚的淡水生态型种群,也预示着耳石形态分析在近缘种判别方面的良好应用前景。     

Reconstructing habitat use of Coilia mystus and Coilia ectenes of the Yangtze River estuary, and of Coilia ectenes of Taihu Lake, based on otolith strontium and calcium

The habitat use and migratory patterns of Osbeck's grenadier anchovy Coilia mystus in the Yangtze estuary and the estuarine tapertail anchovy Coilia ectenes from the Yangtze estuary and Taihu Lake, China, were studied by examining the environmental signatures of strontium and calcium in their otoliths using electron probe microanalysis. The results indicated that Taihu C. ectenes utilizes only freshwater habitats, whereas the habitat use patterns of Yangtze C. ectenes and C. mystus were much more flexible, apparently varying among fresh, brackish and marine areas. The present study suggests that the spawning populations of Yangtze C. ectenes and C. mystus in the Yangtze estuary consist of individuals with different migration histories, and individuals of these two Yangtze Coilia species seem to use a variety of different habitats during the non-spawning seasons.     

长江口邻近水域刀鲚的线粒体控制区序列变异与遗传多样性

经克隆测序获得了采自长江口九段沙、钱塘江口、舟山等3个地点35尾刀鲚(Coilia nasus)的mtDNA控制区全序列,分析了控制区序列的变异和遗传结构。结果显示,长江口邻近水域刀鲚的mtDNA控制区序列具有长度多态性,全长为1214~1291bp,主要是在第358位点处有以"CTA TGT ATT ATA TTA CAT ATA TTA TGG TAT AGT ACA TA"38bp为单位的1~2次片段重复。种群遗传结构分析显示,长江口邻近水域刀鲚的平均单倍型多样性(h)为0.9983,3个群体的平均核苷酸多样性(π)为0.0262,表现出丰富的遗传多样性和较高的进化潜力。3个刀鲚群体间的分化指数FST仅为0.012~0.053,而基因交流值Nm却达9.90~40.62。群体间K2-P遗传距离与AMOVA分析结果也表明,长江口及毗邻地区的刀鲚没有发生地理分化。以线粒体DNA控制区全序列构建的NJ树揭示,3个群体的个体组成了2个谱系,但这2个谱系与地理分群并不相关。依据分子钟理论,推测这两个谱系的分化发生在更新世末期。     

池养刀鲚(Coilia nasus)鱼种的摄食与生长

采用生长测量、摄食节律评估的方法研究了人工养殖备件下刀鲚(Coilia nasus)的摄食和生长特性,旨在为刀鲚积累基础生物学资料,同时为大规模开展刀鲚的池塘养殖提供参考.结果表明:经过153 d的生长期,刀鲚的平均体长从最初的(12.41±2.21 )cm增加到(21.25±2.08)cm,体重从(5.83±0.91)g增加到(40.58±12.98)g;体长与日龄为线性相关(L=0.0558t+13.102,R2=0.97),体重与日龄为指数相关(W=6.5699e0.01231,R2 =0.98),体重与体长之间呈幂函数关系(W=0.0006L3.5924)幂指数b值接近3;刀鲚鱼种有明显的昼夜摄食节律,4:00-8:00是刀鲚鱼种的摄食高峰期,12:00左右摄食活动基本停止,16:00起摄食强度又明显回升,属晨昏摄食;此外还发现,枝角类、桡足类、日本沼虾和(鱼叚)虎鱼是培育刀鲚鱼种较为适宜的饵料生物,但其不同发育阶段适宜饵料生物有所不同,摄食量与饵料的种类和数量有直接关系.     

10‰盐度对长江刀鲚幼鱼装载和运输胁迫中应激指标的影响

采用模拟运输的方法,选取平均体长为(13.58±0.23)cm、平均体质量为(8.55±0.39)g的长江刀鲚幼鱼为实验对象,设置正常应激组和加盐抗应激组(盐度为10‰),每组3个平行,运输结束后将剩余的鱼放回原培育池,研究分析了正常应激组和加盐抗应激组在装载前(BL)、装载后(AL)及运输胁迫2h、4h、6h、8h和恢复24h、96h后,长江刀鲚血浆渗透压、皮质醇、血糖和肝糖原的变化规律及恢复情况。结果显示,正常应激组和加盐抗应激组经装载、8h运输及恢复96h后的成活率分别为20%和100%。运输胁迫导致正常应激组刀鲚血液渗透压整体呈下降趋势,10‰盐度则显著提高血浆渗透压,至运输8h后,血液渗透压达到最高值(0.348±0.002)m Osm/kg。长江刀鲚血浆皮质醇在运输2h后急剧升高达到最大值,而10‰盐度使得运输刀鲚的血浆皮质醇在运输4h后达到峰值(574.71±64.75)ng/m L。运输胁迫导致正常应激组长江刀鲚血糖的明显升高;而加盐抗应激组血糖含量的变化幅度显著低于正常应激组,运输6h后血糖值趋于稳定。肝糖原的变化规律与血糖浓度相对应,推测血糖值的变化主要源于肝脏糖原的动员。实验结果表明,10‰盐度可显著提高血浆渗透压水平,降低其能量物质消耗,避免了撞壁、擦伤掉鳞等强烈的应激反应,显著提高了成活率。     

Environmental influences on the spatio-temporal distribution of Coilia nasus in the Yangtze River estuary

The Yangtze River estuary (YRE) is an important migration channel and foraging habitat for Coilia nasus. Due to its ecological significance and a prioritization of this species’ protection, the need to investigate and analyze environmental relationships of the abundance of Coilia nasus in the YRE as well as develop an understanding of their temporal and spatial distributions is becoming exceedingly important. Using fishery data and environmental survey data from 2009 to 2016, three models including generalized additive mixed models (GAMM), generalized additive models with zero-inflated Poisson distribution (ZIP-GAM) and two-step GAM were used to analyze relationships between environmental factors and the distribution of Coilia nasus in the YRE. The results showed that model fitting of GAMM was more consistent with observations and revealed influences of water temperature, salinity, chlorophyll, and pH on distribution. GAMM demonstrated that higher Coilia nasus abundances were located in waters with water temperature values at 15°C and 30°C, and lower Coilia nasus abundances were located in areas with water temperature values at 10°C and 20°C. All models indicated that the effect of salinity on abundance of Coilia nasus present a multimodal pattern including three peaks at 5, 15, and 25 ppt respectively. Additionally, abundance of Coilia nasus increased with the increase of chlorophyll A in its range of 0–4 mg/L. In a range of 8.0–9.5, higher PH value was more suitable for the aggregation of Coilia nasus. Cross validation was used to evaluate the predictive performance of models and GAMM was found to be the best. The predicted abundance distribution of Coilia nasus in the summer and autumn of 2016 was relatively higher overall than that in winter and spring. The predicted zero abundance distribution pattern was consistent with the sampling presence distribution which was obtained using fishery independent survey data of the year 2009–2015. Facing the urgency protection of Coilia nasus in YRE, results of this study could be used for Coilia nasus conservation and reserve planning.