洱海四种鲤鱼线粒体DNA遗传相似性的初步研究

用6种限制性内切酶对洱海的四种鲤鱼--洱海鲤(C. barbatus)、春鲤(C. longipectoralis)、大眼鲤(C. megalophthalmus)和杞麓鲤(C. carpio chila),其中前三种为洱海特有,进行了线粒体DNA(mtDNA)的限制性片段长度多态性(RFLP)分析,构建了它们的mtDNA限制性内切酶图谱。结果表明,这四种鲤鱼在种内和种间均缺乏mtDNA RFLP。这种现象在鱼类种间的mtDNA的RFLP研究中是罕见的。分析这一现象的原因,可能在于这些物种是同域形成物种,并且其分化时间还相当短。

波兰多甲藻,中国淡水产毒甲藻新记录

2006年,在湖北姊归香溪河高阳镇河段发现一种甲藻,通过光学显微镜和电子扫描显微镜观察,鉴定该种为波兰多甲藻(Peridinium polonicum),中国新记录。文献显示该藻是一种产毒甲藻,可以在水库或池塘形成水华,造成鱼类死亡。该种为目前淡水甲藻产毒的唯一记录,其对环境和生态的影响值得关注。

两个不同江豚群体ISSR遗传多样性初步分析

采用ISSR分子标记对中国水域隶属于不同江豚(Neophocaena phocaenoides)亚种的两个群体即长江群体和渤海群体的遗传多样性进行分析。用19条ISSR引物及3对引物组合对两个群体共36个样品的基因组DNA进行PCR扩增,共得到115个清晰的扩增位点,其中多态性位点48个,多态位点百分率(PPL)为41.71%。POPGENE分析结果表明:两个江豚群体的总体遗传多样性水平相对较低(He=0.1643;Ho=0.2413);长江群体的遗传多样性水平(He=0.1530;Ho=0.2223)稍

鲸类繁殖生物学的研究概况

美国资助发展中国家海洋哺乳类研究项目; 山东大学资助项目

红球藻研究进展

国家自然科学基金资助项目(39570086)

Temperature- and salinity-dependent development of a Nordic strain of Ichthyophthirius multifiliis from rainbow trout

During the twentieth century evidence was presented which suggested the presence of various strains and races of the parasite Ichthyophthirius multifiliis Fouquet. However, ecological profiles of various parasite isolates from different climatic zones are sparse. Such stringent characterizations of parasite development at defined abiotic conditions could provide valuable criteria for the different races: profile comparison from various localities is one way to differentiate these strains. Baseline investigations were therefore performed on the associations between abiotic factors (temperature/salinity) and the development of theronts in tomocysts of I. multifiliis isolated from rainbow trout in a Danish trout farm. It was shown that tomocyst formation and theront development took place between 5 and 30degreesC. Development rates and sizes of theronts were clearly affected by temperature: theronts escaped tomocysts already after 16-27 h at 25degreesC and 30degreesC, whereas this process took 8-9 days at 5degreesC. Likewise, theront size decreased steadily from a maximum of 57.4 x 28.6 mum at 5degreesC to 28.6 x 20.0 mum at 30degreesC. This size variation was only partly associated with the number of theronts that appeared at different temperatures. The lowest number of theronts escaping from one tomocyst was indeed found at 5-7degreesC (mean 329-413). At 11.6, 17.0 and 21degreesC. the highest number of theronts appeared (mean 546-642). However, at 25 and 30degreesC, the number decreased (458 and 424, respectively). Additional studies on the salinity dependent development of the parasite (at 11.6degreesC) showed that salinities above 5 p.p.t. totally inhibited development. Even at 5 p.p.t. the developmental time significantly increased and the number of theronts produced from one tomocyst decreased.

Food consumption and growth of two piscivorous fishes, the mandarin fish and the Chinese snakehead

Rates of maximum food consumption and growth were determined for immature mandarin fish Siniperca chuatsi (47.2-540.2 g) and Chinese snakehead Channa argus (45.0-546.2 g) at 10, 15, 20, 25, 30 and 35 degrees C. The relationship between maximum rate of food consumption (C-max), body weight (W) and temperature (T) was described by the multiple regression equations: lnC(max) = -4.880 + 0.597 lnW+0.284T - 0.0048T(2) for the mandarin fish, and lnC(max)= -6.718 + 0.522 lnW+0.440T-0.0077T(2) for the Chinese snakehead. The optimum temperature for consumption was 29.6 degrees C for the mandarin fish and 28.6 degrees C for the Chinese snakehead. The relationship between growth rate (G), body weight and temperature was ln(G+0.25)= - 0.439 - 0.500 lnW+0.270T - 0.0046T(2) for the mandarin fish, and ln(G+0.25)= - 6.150+ (0.175 - 0.026T) lnW+0.571T - 0.0078T(2) for the Chinese snakehead. The weight exponent in the growth-weight relationship was -0.83 for the mandarin fish, but decreased with increasing temperature for the Chinese snakehead. The optimum temperature for growth was 29.3 degrees C for the mandarin fish, but tended to decrease with increasing weight for the Chinese snakehead, being 30.3 degrees C for a 45-g fish, and 26.1 degrees C for a 550-g fish. (C) 1998 The Fisheries Society of the British Isles.

Hole Rashba effect and g-factor in InP nanowires

The hole Rashba effect and g-factor in InP nanowires in the presence of electric and magnetic fields which bring spin splitting are investigated theoretically in the framework of eight-band effective-mass envelop function theory, by expanding the lateral wave function in Bessel functions. It is well known that the electron Rashba coefficient increases nearly linearly with the electric field. As the Rashba spin splitting is zero at zero k(z) ( the wave vector along the wire direction), the electron g-factor at k(z) = 0 changes little with the electric field. While we find that as the electric field increases, the hole Rashba coefficient increases at first, then decreases. It is noticed that the hole Rashba coefficient is zero at a critical electric field. The hole g-factor at k(z) = 0 changes obviously with the electric field.