不同食物条件下蚤状溞的脂肪酸组成比较研究

在Banta液(牛粪1.5 g 干稻草2 g 沃土20 g 水1000 ml)、酵母、小球藻三种培养条件下,比较研究了蚤状的脂肪酸组成。用GC/MS法分析后结果表明:它们的总脂量变化不大,依次为5.23%、5.46%和6.01%。共检测到15种脂肪酸,其中饱和脂肪酸(SFA)5种,单不饱和脂肪酸(MUFA)4种,多不饱和脂肪酸(PUFA)6种。蚤状以小球藻培养条件下的C 20∶5(EPA)和C 18∶3的含量最高,PUFA占总脂肪酸的34.79%;Banta液组的SFA含量最高,为53.89%;面包酵母组的MUFA含量最高,达60.65%,且富含C 16∶1(n-7)和C 18∶1(n-9),这两种不饱和脂肪酸约占总脂肪酸的56.73%。EPA的含量以小球藻组最高,为14.43%,与自然环境中蚤状的含量相近。酵母组最低,为2.05%。蚤状和其它饵料生物一样,其脂肪酸组成主要随食物特点而变化,也决定于其本身的吸收与合成能力。     

镉对蚤状溞的毒性试验

本文研究了金属镉对蚤状(氵蚤)96小时的急性毒性反应。结果表明镉浓度越高,暴露其间时间越长,蚤状(氵蚤)的活动、蜕皮时间、蜕皮次数以及生长所受影响越大。镉对蚤状(氵蚤)24、48、72、96小时的半数致死浓度分别为1.28ppm、0.39ppm、0.21ppm、0.16ppm。用半数致死浓度估算水体Cd~(2+)对蚤状(氵蚤)的安全浓度为0.0016ppm。     

三氯生对蚤状溞急性毒性效应影响

为探讨三氯生对蚤状溞(Dphnia pulex)的毒性影响,在预试验的基础上,设置了5个试验组[ρ(三氯生)为100,200,400,800和1200μg/L]和空白对照组,开展三氯生对蚤状溞急性毒性试验.在此基础上,设置6个试验组[ρ(三氯生)为5,10,20,40,80和160μg/L]和空白对照组,分析三氯生对蚤...     

温度与盐度对老年低额蚤和蚤状蚤生长及生殖的影响_

温度与盐度对老年低额蚤和蚤状蚤生长及生殖的影响王丹丽，李明云，杨天勇，胡章（宁波大学，３１５０１０）关键词老年低额　，蚤状　，温度，盐度，生长，生殖ＥＦＦＥＣＴＳＯＦＴＥＭＰＥＲＡＴＵＲＥＡＮＤＳＡＬＩＮＩＴＹＯＮＧＲＯＷＴＨＡＮＤＲＥＰＲＯＤＵＣＴ...     

蚤状溞对海水盐度的耐受力研究

The reproduction and survival of Daphnia pulex Straus under salinities of 2,3,4,6,8,10 and 15℃,20℃,25℃ has been stu died.The results show that the alternate effect of salinity and temperature is o utstanding.The developmental rate of D.pulex goes up with the increa se of temperature under a certain salinity,and the total life span reduces with the increase of salinity under a certain temperature. The optimum salinity-tempe rature combination level is salinity 2 and temp.20℃.The upper salinity limit of reproduction is 4.After short-term training between 15～25 ℃and at 25℃,the up per salinity limit of reproduction and survival is 6.     

角突网纹溞和蚤状溞作为泥鳅开口饵料的可行性研究

在水温（25±1）℃的条件下,以熟蛋黄为对照,研究了角突网纹溞（Ceriodaphnia cornuta）和蚤状溞（Daph-nia pulex）作为泥鳅（ Missgurnus arguillicaudatus）开口饵料的可行性。试验泥鳅为3日龄仔鱼,全长为（4.23±0.05） mm,体重为（1.21±0.01） mg,试验周期为20 d。结果显示：角突网纹溞组、蚤状溞组及蛋黄组泥鳅仔鱼的成活率分别为59.00％、38.67％和27.00％,三组之间的差异均达极显著水平;角突网纹溞组、蚤状溞组和对照组的泥鳅仔鱼全长分别为（26.43±1.96） mm、（28.30±7.64） mm和（12.74±0.15） mm,体重分别为（148.98±25.50） mg、（158.02±101.41） mg和（19.36±0.83） mg,两试验组间的全长和体重差异不显著,但均与对照组有极显著差异。结果表明,两种枝角类（尤其是角突网纹溞）作为泥鳅仔鱼的开口饵料,能较大幅度地提高泥鳅仔鱼的成活率,且可获得较大规格的鳅苗,在鳅苗的规模化人工繁育中具有较大的应用价值。     

温度对透明溞生长、生殖和形态可塑性的影响研究

采用实验生态学方法,研究温度对透明溞生长、生殖及其形态可塑性的影响.试验结果表明,在15～27℃温度内,透明溞存活率27℃时最低,为0％,21℃时最高,为80％,15℃时较低,为60％.随温度升高透明溞的产前发育期缩短2～6 d,寿命缩短2～34 d,内禀增长率增加,24℃时达到最高,为0.47 d-1,15℃时最低,...     

定量表达和整体原位杂交研究Doublesex基因在不同生殖状态蚤状溞的表达

为研究doublesex(dsx)基因在不同生殖状态的蚤状溞的时空表达状况,提取不同生殖状态的蚤状溞RNA,采用RT-PCR和Quantitative real-time PCR检测了dsx在不同生殖状态溞体的表达差异,并通过体外转录制备DIG标记的Doublesex的RNA探针;采用整体原位杂交方法研究dsx基因在不同生殖状态的蚤状溞的时空表达状况。结果显示,RT-PCR检测发现dsx在雌雄溞体没有性别特异性的选择性拼接,只有一种相同的转录产物。Real-time PCR显示,dsx在雄溞中表达水平最高,是孤雌溞的2.6倍,两性雌溞的4.9倍,三者之间有显著性差异,表现出性别差异性表达。整体原位杂交发现,在所取样的不同生殖状态溞体中dsx基因也均有表达,但其部位与表达量不同,且在雌雄溞体中表现出性别差异。在雄溞的第一触角和第一胸肢显现得尤为明显,且在复眼中也有表达。孤雌溞和两性雌溞对应部位表达则相对较弱。结果表明,dsx基因很有可能在调控蚤状溞生殖转换和性别分化上起到很大作用。     

Effects of prohibitin on ageing process and reproduction of Daphnia pulex

Daphnia pulex is considered as a great natural food for aquaculture, and Prohibitin (PHB) is a functional protein that plays a key role in eukaryotic cell activities such as proliferation and ageing. To explore the function of PHB in the ageing process of Daphnia pulex (D. pulex), we cloned and analysed the full‐length cDNA of phb1 and phb2. With the growth of D. pulex, expression of two genes have a N curve trend which raised up first and dropped then raised again. Western blot analysis revealed that expression of the PHB proteins increased from 1‐ to 10‐day age, but did not significantly change from 10‐ to 35‐day age. RNAi knockdown of phb1, reduced expression of phb2 and PHB protein, and significantly induced the expression of sex‐determining related gene Doublesex (Dsx), and ageing‐related pathway gene Protein kinase B (Akt). Longevity of the individuals in RNAi group was shortened to 45 days, which was significantly shorter than the other groups. Despite the growth was not significantly different, reproduction amount was significantly impacted by RNAi. These results suggest that PHB significantly affect ageing of D. pulex and may be involved in the reproductive transformation, leading to a decline of reproductive capacity. This study develops our understanding of the ageing mechanism in D. pulex as a potential model organism, provides further insight into the effect of PHB in the processes of ageing and expands our knowledge of molecular mechanisms on ageing and reproduction.     

Effects of food concentration and temperature on development,growth, reproduction and survival of the copepod Pseudodiaptomus euryhalinus

A series of experiments were conducted to evaluate the effect of temperature and the microalgae Isochrysis sp. concentration on the copepod Pseudodiaptomus euryhalinus cultured in laboratory conditions. First, the ingestion rate of P. euryhalinus was evaluated with different concentrations of Isochrysis sp. [2.74, 5.47, 8.21, 10.94 and 16.41 µg mL^?1 organic dry weight (ODW)] during 24 h, at a temperature of 24.3 ± 0.3 °C. The ingestion rate increased in direct proportion to microalgae concentration, reaching an asymptotic point at 16.41 µg mL^?1. P. euryhalinus was then cultured for 11 days at 24.4 ± 0.3 °C with different concentrations of Isochrysis sp. (5.47, 8.21, 10.94 and 16.41 µg mL^?1 ODW) in order to quantify the optimal food density. It was observed that food concentration did not have a significant effect on the development, growth, maturity, fecundity and survival of P. euryhalinus. The effect of different temperatures (19.4 ± 0.5, 21.9 ± 1.0, 24.2 ± 0.3, 27.8 ± 0.5 and 30.1 ± 0.8 °C) on the development, growth, survival and sex ratio of P. euryhalinus fed with Isochrysis sp. at 5.47 µg mL^?1 ODW was evaluated for 11 days of culture. The temperature had an inversely proportional effect on the time of development, and highest survival and growth were observed at 24.2 ± 0.3 °C. Finally, the effects of different temperatures (21.7 ± 0.5, 24.2 ± 0.3, 27.2 ± 0.3 and 30.7 ± 0.6 °C) in nauplii production of adult copepods were evaluated during 11 days. Nauplii production increased in direct proportion with the temperature. These results suggest that the optimum temperature and food concentration for P. euryhalinus culture are 24.2 ± 0.3 °C and 5.47 µg mL^?1 ODW of Isochrysis sp., respectively.     

Effects of plant oligosaccharides derived from dragon fruit on growth,reproduction and survival of freshwater crustacean Daphnia magna

The freshwater crustacean Daphnia is widely used as live food for ornamental fish. To increase production, food supplementations are required when culturing Daphnia. Here, we aimed to clarify the effects of plant oligosaccharides derived from dragon fruit (DFO) on growth rate, egg production, number of first clutch juveniles and survival of Daphnia supplemented with five different concentrations of DFO, that is 0, 1, 3, 9, 27 mg/L. The results showed the growth and reproduction of Daphnia were enhanced when supplemented with DFO. Growth rate of Daphnia supplemented with 9 mg/L DFO was the highest among all treatments. The time that Daphnia produced the first clutch eggs was shorter in high concentration of DFO (3, 9, 27 mg/L). The number of juveniles in the first clutch increased in treatments of higher concentration of DFO (3, 9, 27 mg/L). These results suggest that plant oligosaccharides derived from dragon fruit increase growth and fecundity of Daphnia. Survival rates of Daphnia were 100% except for the treatment supplemented with 27 mg/L of DFO in which the survival rate was reduced to 87%. To our knowledge, this is the first functional evidence demonstrating that oligosaccharides derived from dragon fruit enhance growth and fecundity of Daphnia.     

温度和光照对铜绿微囊藻、大型溞和金鱼藻共同培养的影响

为了解温度和光照对生物操纵和水生植被植物恢复的影响,将选择铜绿微囊藻、大型溞和金鱼藻分别作为浮游植物、浮游动物和大型沉水植物的代表,将其在含有11mg/L的氮浓度和不同磷浓度（0.2、0.5、1.0、1.5mg/L）的培养液中共培养,研究不同温度（15、20、25、30℃）和光照强度（1000、2200、3400、4500lx）对藻-溞-草三者共培养的影响。结果表明：温度对生物操纵和水生植被物恢复影响显著。温度为15℃时,磷浓度的改变对控藻效果的影响不大,但金鱼藻的增长率较其它温度时低,磷浓度在0.2～1.5mg/L时,金鱼藻的增长率均高于铜绿微囊藻;温度介于20～25℃时,大型溞的增长率比较大,生物操纵效果较好,且磷浓度为0.2mg/L的磷浓度时对金鱼藻的生长最有利,控藻效果较好;30℃时,大型溞增长率最较小,在此温度下,且当磷浓度达到1.5mg/L时,铜绿微囊藻出现正增长,此时不能有效控制铜绿微囊藻。光照强度介于1100～2200lx时,所有磷浓度下金鱼藻和大型溞的增长率都高于铜绿微囊藻,控藻效果明显;光照强度介于3400～4500lx时,磷浓度对生物操纵和水生植被恢复的影响要高于光照因素,且磷浓度在0.2～0.5mg/L时控藻效果好,更有利于恢复水生植被植物。     

化纤废水中主要污染物对大型蚤的急性毒性及联合毒性作用

研究了化纤废水中主要污染物乙醛、对苯二甲酸和乙二醇对大型蚤的急性毒性及联合毒性作用。结果表明,乙醛对大型蚤４８ｈ－ＬＣ５０、９６ｈ－ＬＣ５０值分别为１６．８、４．２ｍｇ／Ｌ,安全质量浓度为０．４２ｍｇ／Ｌ;对苯二甲酸对大型蚤４８ｈ－ＬＣ５０,９６ｈ－ＬＣ５０值分别为３１６５．２、１１１１．７ｍｇ／Ｌ,安全质量浓度为１１１．２ｍｇ／Ｌ;乙二醇对大型蚤４８ｈ－ＬＣ５０、９６ｈ－ＬＣ５０值分别为３８６７