植物油替代鱼油对虹鳟、花鲈和大黄鱼组织结构的影响

以初始体重分别为(11.24±0.07 g)、(18.60±0.36 g)和(8.93±0.21 g)的虹鳟、鲈鱼和大黄鱼幼鱼为研究对象,用植物油(亚麻籽油:豆油=1:1)分别替代0%(FO,对照组)、50%(FV)和100%(VO)的鱼油来配制三种等氮(粗蛋白含量为41%)等脂(粗脂肪含量为12%)的实验饲料。通过投喂实验探讨不同植物油替代鱼油水平对虹鳟(淡水鱼)、鲈鱼(广盐性鱼类)和大黄鱼(海水鱼)肝脏和肠道组织结构的影响差异。70 d投喂实验后发现,随着替代水平增加虹鳟、鲈鱼和大黄鱼的肝细胞中脂肪滴累积程度逐渐增高,相同替代水平下肝细胞中脂肪滴累积程度为大黄鱼>鲈鱼>虹鳟;肠道组织中杯状细胞随植物油替代水平升高而增多,而在大黄鱼全植物油组出现脂肪滴累积和上皮细胞死亡现象。以上结果表明植物油替代鱼油对虹鳟组织结构影响最小对大黄鱼影响最大。     

大黄鱼幼鱼饲料中大豆磷脂油与菜籽油的适宜配比

配制浓缩大豆磷脂油与精制菜籽油的添加比例分别为0:6、2:4、4:2和6:0的4种等氮、等能和等脂的饲料(P0R6、P2R4、P4R2和P6R0),在海水浮式网箱中,养殖初始体重为(20.84±0.05)g的大黄鱼(Larimichthys crocea)幼鱼51 d,每个处理组设3个重复,每个重复40尾鱼。通过评定2种油脂的不同配比对大黄鱼幼鱼的生长、体组成和脂肪酸组成的影响,以得出大黄鱼幼鱼饲料中大豆磷脂油与菜籽油的适宜配比。结果显示,各组实验鱼的存活率均高于91%,且无显著差异(P0.05)。P2R4组实验鱼的特定生长率显著高于P4R2和P6R0组(P0.05)。P2R4组实验鱼的蛋白质沉积率和脂肪沉积率显著高于P0R6和P6R0组(P0.05)。P0R6和P2R4组全鱼的粗脂肪含量显著高于P4R2和P6R0组(P0.05)。全鱼和肌肉的脂肪酸组成受实验鱼所摄食饲料的脂肪酸组成的影响。P6R0饲料显著降低了实验鱼的肝脏脂肪含量和肥满度(P0.05)。研究表明,大黄鱼幼鱼饲料中浓缩大豆磷脂油与精制菜籽油的适宜配比为2:4。     

The Effects of Soybean Lecithin Supplementation to a Practical Diet Formulation on Juvenile Channel Catfish,Ictalurus punctatus: Growth,Survival, Hematology,Innate Immune Activity,and Lipid Biochemistry

A feeding trial was conducted to determine the effects of soy lecithin supplementation on production performance of juvenile channel catfish, Ictalurus punctatus (mean ± SE; 5.8 ± 0 g). The basal diet consisted of a practical dietary formulation for channel catfish, containing 4.3% endogenous phospholipids (PL) from dietary ingredients, to which supplemental PL from soybean lecithin were added. The study diets were 1 control and 2 experimental diets to which 0, 2, or 4% supplemental lecithin was added, respectively. Soy lecithin inclusion did not affect survival, growth, feed consumption, whole‐body total lipid, innate immune response, plasma cholesterol or triglyceride concentrations, or hepatosomatic index. Feed conversion (gain/intake) improved in fish fed 4% supplemental lecithin compared with 0% lecithin. Whole‐body crude protein was greater in fish fed 2% supplemental lecithin compared with 0% lecithin, while 4% supplemental lecithin was intermediate. Phosphatidylcholine (PC) content was greater in fish fed 2 or 4% lecithin than 0% lecithin. Plasma concentrations of PC were inversely proportional to dietary concentrations. Liver glycogen was greater in fish fed 0% lecithin compared with 2 or 4% lecithin. Liver lipid and phospholipid were lower in fish fed 0% lecithin than 2 or 4% lecithin. The dietary phospholipid requirement, if any, of juvenile channel catfish for growth and survival is less than or equal to 4.3% (1.5% PC) of the diet. Feed conversion is improved in channel catfish fed diets supplemented with 4% soy lecithin (7.2% phospholipid; 5.1% PC), which might offset additional costs due to phospholipid supplementation. Dietary soy lecithin inclusion altered plasma and liver lipid composition, but it is unknown whether these effects can alter the ability of juvenile catfish to survive and grow under various conditions.     

Proximate,Fatty Acid,and Amino Acid Compositions of Fish Muscle and Egg Tissue of Hilsa (Tenualosa) ilisha

The total lipid profile including the fatty acid composition and amino acid composition in eggs of Hilsa (Tenualosa) ilisha was studied in comparison with its muscle tissue. The eggs contained 30.4% lipid (on dry basis), which was 1.2 times higher than that of the muscle tissue lipid. The major portion of the egg lipid was composed of wax ester (about 47.6%) followed by triacylglycerol (TAG), phospholipid (PL), and cholesterol. The muscle tissue lipid contained TAG as the major fraction (41.8 ± 1.48%). Total amount of polyunsaturated fatty acids (PUFAs) was about 43 ± 0.05% and 32.4 ± 0.24% in egg PL and body tissue PL fractions, respectively. Among fatty alcohols of egg wax ester, 16:0 alcohol is predominant (56.4 ± 3.02%). Both the egg and muscle tissues are rich in all essential amino acids. The results indicate that muscle and eggs from Hilsa are rich in essential amino acids, PUFA, and phospholipids which are essential for human health and membrane development.     

Physiological and molecular changes in large yellow croaker (Pseudosciaena crocea R.) with high‐fat diet‐induced fatty liver disease

Fatty liver disease is regularly observed in cultured large yellow croaker, and the disease leads to lower growth rates and reduced harvest yields. The goal of this study was to achieve a more detailed understanding of the physiological and molecular changes in response to high‐fat diet‐induced fatty liver in large yellow croaker. Large yellow croaker fed a high‐fat diet (HFD) for 9 weeks developed hepatic steatosis characterized by histological observation and significantly increased plasma triglyceride levels and serum alanine aminotransferase (ALT) activities. However, no significant differences in serum total protein, glucose, cholesterol, non‐esterified free fatty acids (NEFA), aspartate aminotransferase, high‐density lipoprotein and low‐density lipoprotein were observed between the normal diet and the high‐fat diet (HFD) group. The fatty acid composition of tissue lipids was not affected significantly by dietary lipid levels. Gene expression analysis demonstrated that the HFD decreased fatty acid synthase expression and increased PPARγ expression, but had no effect on lipoprotein lipase and PPARα expression. These results suggest that the HFD‐induced physiological changes and fatty liver may be due to the alteration of related gene expression. As such, further investigations of the metabolic pathways and differentially expressed genes are of particular significance in the mechanistic study and understanding of HFD‐induced fatty liver disease.     

Optimal dietary lipid level for large yellow croaker (Pseudosciaena crocea) larvae

A 30‐day feeding experiment was conducted in blue tanks (70 × 50 × 60 cm, water volume 180 L) to determine the effects of dietary lipid levels on the survival, growth and body composition of large yellow croaker (Pseudosciaena crocea) larvae (12 days after hatchery, with initial average weight 1.93 ± 0.11 mg). Five practical microdiets, containing 83 g kg^?1 (Diet 1), 126 g kg^?1 (Diet 2), 164 g kg^?1 (Diet 3), 204 g kg^?1 (Diet 4) and 248 g kg^?1 lipid (Diet 5), were formulated. Live feeds (Artemia sinicia nauplii and live copepods) were used as the control diet (Diet 6). Each diet was randomly assigned to triplicate groups of tanks, and each tank was stocked with 3500 larvae. During the experiment, water temperature was maintained at 23(±1) °C, pH 8.0 (±0.2) and salinity 25 (±2) g L^?1. The results showed that dietary lipid significantly influenced the survival and growth of large yellow croaker larvae. Survival increased with the increase of dietary lipid from 83 to 164 g kg^?1, and then decreased. The survival of larvae fed the diet with 83 g kg^?1 lipid (16.1%) was significantly lower than that of larvae fed other diets. However, the survival in larvae fed the diet with 16.4 g kg^?1 lipid was the highest compared with other artificial microdiets. Specific growth rate (SGR) significantly increased with increasing dietary lipid level from 83 to 164 g kg^?1 (P < 0.05), and then decreased. The SGR in larvae fed the diet with 164 g kg^?1 lipid (10.0% per day) was comparable with 204 g kg^?1 lipid (9.6% per day), but were significantly higher than other microdiets (P < 0.05). On the basis of survival and SGR, the optimum dietary lipid level was estimated to be 172 and 177 g kg^?1 of diet using second‐order polynomial regression analysis respectively.     

Effects of dietary carbohydrate and lipid levels on growth performance,feed utilization,body composition and non‐specific immunity of large yellow croaker (Larimichthys crocea)

The present study was conducted to investigate the effects of dietary lipid, carbohydrate and their interactions on growth performance, feed utilization, body composition and non‐specific immunity of large yellow croaker (Larimichthys crocea). The experimental fish were fed the diets with graded levels of dietary crude lipid (80, 110 and 140 g/kg diet) and dietary carbohydrate (60, 90 and 120 g/kg diet) for 7 weeks. Results showed that the specific growth rate decreased significantly as dietary carbohydrate increased, which partly resulted from the progressively reduced feed intake and protein efficiency ratio. Meanwhile, the result of postprandial glucose content confirmed glucose intolerance of the croaker. However, the specific growth rate was not significantly altered by dietary lipid, but the feed intake was remarkably reduced. The different growth performance and feed utilization of croaker in response to dietary lipid and carbohydrate resulted in the variation of body composition. In addition, the activity of lysozyme and classical complement pathway was significantly improved in croaker fed the diet with 110 g/kg lipid. In above, dietary carbohydrate and lipid of large yellow croaker should be maintained at 60 and 110 g/kg diet, respectively, based on the above indices.     

官井洋大黄鱼夏季食物组成和摄食习性

2010年6月在福建省官井洋海域收集579尾大黄鱼(Larimichthys crocea)标本进行胃含物分析,同步采集取样点附近水域浮游动物及张网样品,比较大黄鱼胃含物种类与水域中生物种类组成的相似性。结果表明:大黄鱼食物种类共32种,种类广泛。大黄鱼主要摄食十足类(相对重要性指标百分比%IRI=49.14%)、鱼类(%IRI=20.47%)、磷虾类(%IRI=18.31%)和糠虾类(%IRI=2.34%),具有以游泳动物、浮游动物为主要食物对象的肉食性摄食习性。细螯虾(Leptochela gracilis)(相对重要性指标IRI=976.10,%IRI=35.38%)和中华假磷虾(Pseudeuphausia sinica)(IRI=505.27,%IRI=18.31%)为大黄鱼食物组成中最重要的食物种类。海区中,浮游动物以桡足类为主,占所有浮游动物总丰度的45.03%,主要优势种为太平洋纺锤水蚤(Acartia pacifica,优势度Y=0.14)、双刺唇角水蚤(Labidocera bipinnata,Y=0.09)和中华哲水蚤(Calanus sinicus,Y=0.06);张网渔获物共鉴定91种,主要为细螯虾、白姑鱼(Argyrosomus argentatus)、大黄鱼(Larimichthys crocea)蟳、双斑(Charybdis bimaculata)、三疣梭子蟹(Portunustrituberculatus)、银鲳(Pampus argenteus)鮻和棱(Liza carinatus)。研究表明,大黄鱼对食物种类具有明显的选择性,主要体现在喜好追逐捕食海区中的小型虾类和仔、稚、幼鱼以及体型相对较大的浮游动物磷虾类和糠虾类。     

禁食对养殖大黄鱼体成分、肌肉脂肪酸组成和血清生化指标的影响

为了探讨禁食对大黄鱼体成分、肌肉脂肪酸组成和血清生化指标的影响,从海上网箱选择规格相近、健康的养殖大黄鱼105尾[平均体质量(249.07±7.28)g]进行禁食实验,分别在实验开始时及禁食后第3、7、14、21、28、35、42和49天采集实验鱼肌肉和血液样品,进行肌肉营养成分和血清生化指标的测定。结果发现,随着禁食时间的延长,大黄鱼肌肉中水分和粗灰分含量呈现升高的趋势,粗脂肪含量呈现下降的趋势,粗蛋白含量在禁食后第21天下降后基本保持稳定;肌肉中饱和脂肪酸(SFA)和单不饱和脂肪酸(MUFA)含量均无显著变化,多不饱和脂肪酸(PUFA)和n-3系列高度不饱和脂肪酸(n-3HUFA)总量呈现下降的趋势。禁食后第3天血清中的谷丙转氨酶(ALT)、谷草转氨酶(AST)、乳酸脱氢酶(LDH)、葡萄糖(GLU)、钾离子(K~+)、钙离子(Ca~(2+))、钠离子(Na~(+)))和氯离子(Cl~-)含量显著上升;甘油三酯(TG)、总胆固醇(CHOL)含量显著下降;血清总蛋白(TP)、高密度脂蛋白胆固醇(HDL-C)、低密度脂蛋白胆固醇(LDL-C)和碱性磷酸酶(ALP)无显著变化。研究表明,随着禁食时间的延长,血清中除了Na~+和Cl~-含量出现波动性上升外,血清中的葡萄糖、蛋白质、脂类、K~+和Ca~(2+)含量以及血清代谢酶活性均出现波动式下降,表明大黄鱼禁食期间主要以脂类作为能量来源,体内营养物质代谢活动强度呈波浪形的起伏变化,随着禁食时间的延长机体代谢活动趋于减弱,但免疫功能和代谢机能未受到明显影响。     

黄海南部、东海北部夏秋季小黄鱼数量分布及与浮游动物的关系

对夏秋季黄海南部、东海北部海域的小黄鱼和浮游动物的数量分布及其它们之间的关系进行了研究,结果表明:夏秋季节,黄海南部、东海北部小黄鱼主要出现在大沙、江外、吕四和沙外渔场,夏季最高生物量分布区出现在长江口和江外渔场交界处的31°30′N、125°00′E海域,秋季最高生物量分布区出现在大沙和沙外渔场交界处的32°30′N、125°00′E海域。2个季节浮游动物优势种的组成主要以浮游甲壳动物、浮游幼体以及毛颚类动物为主。浮游动物有2个密集分布区:一个在近岸一侧123°00′E经度线附近,夏季呈南北方向分布,秋季呈西北-东南走向;另一个在32°00′N、125°00′E附近海域。从夏季到秋季,浮游动物优势种的组成有了较大的更替,优势种的范围更加扩大;夏季占绝对优势的中华哲水蚤到秋季已经不在优势种之列。夏秋季小黄鱼主要分布区与浮游动物的高密度分布区存在着良好的对应关系。夏季小黄鱼和其他浮游食性鱼类的强烈的摄食影响可能造成了秋季浮游动物丰度的急剧下降。小黄鱼主要分布区内饵料浮游动物优势种的季节变化可能对其食物选择的变化有重要的影响。     

皱纹盘鲍内脏脂质分析

对皱纹盘鲍内脏脂质进行了分析。采用Folch法提取内脏总脂,硅胶柱层析对中性脂及磷脂进行分离;TLC法对中性脂、磷脂不同组分进行分离与其主要组分的制备;10%硫酸—甲醇对样品进行甲酯化,通过气相色谱法对其进行脂肪酸分析比较。结果表明,皱纹盘鲍内脏中磷脂含量可达31.58%,不饱和脂肪酸在磷脂中含量显著高于中性脂中含量。磷脂中含有一定量的缩醛磷脂,磷酯酰乙醇胺(PE)中缩醛型磷脂含量可达50%。研究表明,皱纹盘鲍内脏中含有丰富的磷脂,多不饱和脂肪酸,并含有一定量的缩醛磷脂,具有较好的食用和药用价值,应得到充分利用。     

饲料中添加甘氨酸可提高大黄鱼(Larimichthys crocea)的抗氧化和抗应激能力

为研究饲料甘氨酸对大黄鱼(Larimichthys crocea)抗氧化和抗应激反应的影响,将初始体重为(130.35±8.37)g的大黄鱼随机分成6组,每组3个重复,每个重复(网箱)50尾鱼.在基础饲料中分别添加不同梯度的甘氨酸(0、0.6％、1.2％、2.4％、4.8％和6.0％),配制出甘氨酸实测含量分别为(1.58％、2.15％、2.75％、3.96％、6.33％和7.51％)的6种实验饲料.经过30 d养殖后,对大黄鱼进行拖网应激实验.结果表明,养殖实验结束后,饲料处理未对大黄鱼的存活和体成分产生显著影响.肝脏总抗氧化能力在饲料甘氨酸含量为2.75％时达到最大值,而丙二醛的含量在甘氨酸含量为3.96％时达到最小值,但与2.75％组无显著差异(P＞0.05).以肝脏总抗氧化能力为评价指标,根据二次曲线回归模型得出大黄鱼饲料中甘氨酸的适宜含量为3.57％.血清谷草转氨酶和谷丙转氨酶的活性均在饲料甘氨酸含量为2.75％时呈现最小值(P＜0.05).在拖网应激前,饲料甘氨酸含量为2.75％时,大黄鱼血清皮质醇的含量最高.在拖网应激后,该处理的大黄鱼血清皮质醇的变化幅度最小,而此时的血糖维持在较高水平.综合考虑大黄鱼的抗氧化和抗应激能力,本研究推荐大黄鱼饲料中甘氨酸的适宜含量为2.75％-3.57％.     

Oxidative stability of salmon and herring roe lipids and their dietary effect on plasma cholesterol levels of rats

ABSTRACT:   The oxidative stability of lipids from salmon roe and herring roe was compared with those of commercial fish oils originated from sardine and tuna. Both fish roe lipids contained high amounts of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). Total EPA and DHA was more than 35% of total fatty acids in both roe lipids. On the basis of oxygen consumption, fish roe lipids showed the higher oxidative stability than both fish oils. This tendency in oxidative stabilities was also confirmed by the determination of propanal formation during oxidation. Analyses of lipid compositions suggested that the higher oxidative stabilities of fish roe lipids would be mainly due to the presence of phospholipids in them. Dietary effects of salmon and herring roe lipids were also determined. Little increase in total cholesterol level was observed in plasma lipids in rats fed salmon and herring roe lipids, although cholesterol content in fish roe lipids were 6.3% and 9.7% of total lipids for salmon roe and herring roe.     

Effects of dietary protein levels on the growth,survival, amylase and trypsin activities in large yellow croaker,Pseudosciaena Crocea R., larvae

A feeding trial was conducted to investigate the effects of dietary graded protein levels on the growth, survival, amylase and trypsin activities of large yellow croaker (Pseudosciaena crocea R.) larvae from 12 to 42 days after hatching (DAH). Five approximately isoenergetic microbound diets (16.65 MJ/kg diet) were formulated to contain different protein (47.1%, 52.0%, 57.1%, 62.2% and 67.5%) levels. Frozen copepods, containing 54.5% crude protein (CP), 6.0% crude lipid, 27.2% ash and 6.7% glycogen, were used as a control. Each diet was randomly fed to triplicate groups of larvae with an initial mean body weight of 1.76 ± 0.09 mg (mean ± SD) in 180 L white plastic tanks, and each tank was stocked initially with 3500 larvae. Both the survival and the specific growth rate (SGR) of large yellow croaker larvae significantly increased with increasing dietary protein level up to 57.1%, and decreased thereafter. Frozen copepods resulted in intermediate survival and low SGR compared with the other diets. Whole‐body moisture and protein of larvae were not significantly affected by the dietary protein level. In contrast, whole‐body lipid of larvae fed diet with 47.1% CP was significantly higher (P<0.05) than those from fish fed the diets containing more than 57.1% CP. Additionally, fish fed the frozen copepods had the lowest whole‐body protein and lipid. The amylase‐specific activity increased with increasing dietary carbohydrate level during the period of this experiment. However, trypsin activity was not significantly affected by the dietary protein content before 42 DAH, indicating a later onset of trypsin than amylase in the regulation of enzymatic synthesis induced by a dietary substrate.     

Influence of dietary biotin levels on growth and non‐specific immune response in large yellow croaker,Larimichthys crocea R

A 9‐week feeding experiment was conducted to determine the effect of dietary biotin levels on growth performance and non‐specific immune response of large yellow croaker. Fish (6.16 ± 0.09 g) were fed twice daily to apparent satiation with diets containing 0.00 (as the basal diet), 0.01, 0.05, 0.25, 1.24 and 6.22 mg biotin kg^?1 diet. Results showed that fish fed the basal diet had the lowest survival rate, and fish fed 0.05 mg kg^?1 dietary biotin achieved significantly higher final weight and weight gain. Dietary biotin levels had no significant influence on carcass crude lipid, moisture and ash content, but significantly influenced the carcass crude protein. Liver biotin concentration significantly increased with the supplementation of biotin, but no tissue saturation was found within the supplementation scope of biotin. Broken‐line regression analysis of weight gain showed that juvenile large yellow croaker requires a minimum dietary biotin of 0.039 mg kg^?1 for maximal growth. The analyses of serum parameters showed that the moderate‐ (0.05 mg kg^?1) and high‐dose (6.22 mg kg^?1) dietary biotin significantly improved both lysozyme and alternative complement pathway activities, indicating dietary biotin within a certain range could improve the non‐specific immune response of large yellow croaker.     

Lipid class composition of benthic-pelagic fishes (Cottocomephorus, Cottoidei) from Lake Baikal

A study was made of the lipid class composition in liver, gonads and red and white muscles of two endemic Baikal fish species Cottocomephorus grewingki and Cottocomephorus inermis. The main lipid classes were triacylglycerols and phospholipids. The highest levels of triacylglycerol (81.8%) were found in the liver of C. inermis males, and of phospholipid (38.3%) – in males testes of both species. The main phospholipid classes were phosphatidylcholine and phosphatidylethanolamine, which varied in examined organs and tissues in both fish species from 44.3 to 78.7%, and from 16.8 to 42.1%, respectively.     

Effects of Dietary Carbohydrate‐to‐lipid Ratio on Growth Performance,Body Composition,Digestive Enzyme Activities,and Hepatic Enzyme Activities in Juvenile Large Yellow Croaker,Larimichthys crocea

An 8‐wk feeding trial was conducted to investigate the effects of dietary carbohydrate‐to‐lipid ratios (CHO : L) on growth performance, body composition, digestive enzyme activities, and hepatic enzyme activities of juvenile large yellow croaker, Larimichthys crocea. Six isonitrogenous (45% crude protein) and isoenergetic (18 kJ/g gross energy) diets with varying CHO : L ratios (0.07, 0.48, 1.20, 2.19, 4.81, and 10.48) were fed to triplicate groups of large yellow croaker in floating sea cages. Results showed that the highest specific growth rate (SGR) was found in fish fed diets with CHO : L ratio of 2.19. Fish fed the lower (0.07 and 0.48) CHO : L ratios tended to produce lower growth (P < 0.05). The whole‐body lipid content significantly decreased, while hepatosomatic index, liver glycogen content, and plasma glucose concentration significantly increased as dietary CHO : L ratios increased (P < 0.05). Plasma total cholesterol, triglyceride, and low‐density lipoprotein cholesterol concentrations significantly decreased with elevated dietary CHO : L ratios (P < 0.05). The increasing dietary CHO : L ratios significantly stimulated the activities of intestinal amylase and hepatic pyruvate kinase and depressed the activity of hepatic phosphoenolpyruvate carboxykinase (P < 0.05). Based on a second‐order polynomial regression analysis of SGR, 2.38 was determined as the optimal dietary CHO : L ratio for juvenile large yellow croaker.     

大黄鱼中期染色体面积和物理长度的测定

为获知大黄鱼染色体的物理长度,实验采用流式细胞术测定了大黄鱼基因组大小,并利用显微图像分析技术测定了大黄鱼24对染色体的面积和累积光密度(IOD),据此估算了大黄鱼染色体的物理长度。结果显示,大黄鱼基因组大小约为(725.25±14.65)Mb;染色体相对面积最小为2.26%±0.08%,最大为4.83%±0.08%;染色体相对IOD最小为1.80%±0.32%,最大为5.04%±0.15%;物理长度最小的是24号染色体,为(13.1±3.37)Mb,其他染色体的物理长度为(24.4±6.21)~(36.6±1.62)Mb。染色体的物理长度与相对面积、相对长度分别成正线性相关。其中,物理长度-相对面积的相关系数大于物理长度-相对长度。显微图像还显示,同一基因组中的染色体碘化丙啶(PI)着色不完全均一,非同源染色体间、部分同源染色体间以及染色体不同位置均存在荧光强度的差异。研究结果为大黄鱼染色体识别与配对提供了新的数量标记,也为深入解析大黄鱼基因组结构提供基础数据。     

Distribution of the early life stages of small yellow croaker in the Yangtze River estuary and adjacent waters

The horizontal distribution of the early life stages of small yellow croaker Larimichthys polyactis in the Yangtze River estuary and its adjacent area was investigated through six ichthyoplankton surveys conducted during the period of mid-April to mid-July 2015. A total of seven eggs and 2461 larvae and juveniles of small yellow croaker were collected. Abundance of the specimens was highest in mid-May and lowest in mid-July. The composition of the different development stages of small yellow croaker varied among the six cruises, although post-flexion larvae and juveniles dominated the ichthyoplankton collection in each cruise. Specimens at different development stages showed different distribution patterns in the study area. The eggs, yolk-sac and pre-flexion larvae were mainly collected at stations with depth exceeding 30 m, while post-flexion larvae and juveniles were mainly distributed in the relatively shallow waters near to the mouth of the Yangtze River. In conclusion, the study suggested that the study area had largely lost the ecological function to support small yellow croaker spawning, although it could still serve as nursery ground for the species.