美国鲥鱼对我国淡水生态系统的潜在入侵风险(英文)

近年来美国鲥鱼已被引入到我国的上海和广东等地进行水产养殖。本实验报道了在纯淡水人工养殖条件下美国鲥鱼的繁殖和生长情况。人工养殖鲥鱼的生长速度接近美国北卡罗莱纳州沿岸野生鲥鱼的生长速度,而高于特拉华河野生鲥鱼的生长速度;人工养殖的2龄鲥鱼既可以在养殖池中自然产卵,也可以通过注射激素人工诱导产卵,其平均受精率、孵化率和仔鱼17天内的存活率分别约15%、75%和54%。这一结果表明,尽管鲥鱼是在海水中进行繁殖的洄游性鱼类,但在生长环境适宜的淡水条件下同样可以正常生长,并达到性成熟和繁育后代,有可能在适宜的淡水水

蓖齿眼子菜对栅藻和微囊藻的他感作用及其参数

主要报道篦齿眼子菜 (俗称红线草 )的种植水抽滤液对栅藻、微囊藻生长的他感作用试验。应用修正的逻辑斯谛 (Logistic)方程和Lotka Volterra种群竞争模型来计算篦齿眼子菜对藻类的他感作用参数。纯培养试验结果表明 :种植水抽滤液对栅藻生物量和生长率都有一定的促进作用。当浓度大于等于 5 0 %时 ,对栅藻生长的影响则是有抑制效应 ,他感作用效应与种植水的浓度没有明显的相关性 ,他感作用参数平均为 - 0 0 2 6。所有浓度设对照。微囊藻的生长都有明显的抑制作用 ,他感作用参数平均为 - 0

长江江豚对八里江江段的利用及其栖息地现状的初步评价

通过定点和流动观察的方法 ,作者使用行为指数和栖息地利用指数定量分析了长江江豚 (Neophocaenaphocaenoidesasiaeorientalis)于 1996～ 2 0 0 0年间对八里江江段的利用和选择状况。结果表明 :江豚在八里江江段的行为指数大小顺序为摄食 >抚幼 >玩耍 >休息 ,摄食和抚幼是江豚在八里江江段的优势行为 ;江豚栖息于离岸距离 10 0～ 30 0m的近岸带占 81 8% ,栖息于水深小于 9m的水区占 73 3% ;江豚分布密度随水深增加而逐步递减 (典型的指数分布

鲫鱼囊胚细胞干扰素的诱导及部分特性

用紫外线灭活的草鱼呼肠孤病毒 (GCRV)诱导鲫鱼囊胚细胞 (CAB)能产生一种高滴度的抗病毒物质。这种物质在 5 6℃及 pH 2～ 11稳定 ;对胰蛋白酶敏感 ;抗病毒活性受被保护细胞的密度、培养温度及保护时间的影响 ;不能被GCRV的特异性抗体中和 ;无直接杀病毒作用 ;抗病毒机制依赖于细胞内RNA和蛋白质的合成 ;在多种鱼类培养细胞中具有抑制病毒作用。这些特性与哺乳类α/ β干扰素一致 ,是一种鲫鱼干扰素

养虾水体环境因子变化与对虾病毒病之间的关系

研究养虾水体的盐度、溶氧量及pH值等主要理化指标的变化与对虾暴发性病毒病害大流行之间的关系 .以低剂量病毒感染中国对虾 (Penaeuschinensis) ,人工改变海水盐度、溶氧量、pH值等理化指标 ,发现其变化与对虾发病死亡之间存在明显的诱发关系 .结果对阐明对虾暴发病毒性流行病成因及指导虾农科学养虾具有重要参考价值 .

水体腐殖酸对甲氰菊酯的生物可利用性与急性毒性的影响

本文在实验室淡水试验系统中，研究了天然水体腐殖酸对甲氰菊酯对草鱼（Ｃｔｅｎｏｐｈａｒｙｎｇｏｄｏｎｉｄｅｌｌｕｓ）的生物积累和急性毒性的影响。研究结果表明：当水体中腐殖酸浓度为５和１０ｍｇ／Ｌ时，甲氰菊酯对草鱼的生物可利用性以及它对草鱼的急性毒性均呈有意义地减少趋势，而且这种影响的程度随着水体腐殖酸浓度的增加而增大。

三倍体白鲫的生物学特性

由人工诱导的异源四倍体白鲫雄鱼与正常的二倍体白鲫雌鱼交配获得的异源三倍体白鲫，其主要生物学特性同二倍体白鲫进行比较研究表明，三倍体白鲫具有体形较大、相对体高和相对尾柄高较高、侧线上下鳞数目较多的形态特征，仍保留着二倍体白鲫以浮游植物为主的植食性营养方式，雌雄均不育，比二倍体生长快，网箱养殖１１２天后，体重比二倍体平均增加３２．３８％。试验证实三倍体白鲫是一个具有养殖生产前景的新对象。

Isolation of a novel cyanophage infectious to the filamentous cyanobacterium Planktothrix agardhii (Cyanophyceae) from Lake Donghu, China

A previously unknown cyanophage, PaV-LD (Planktothrix agardhii Virus isolated from Lake Donghu), which causes lysis of the bloom-forming filamentous cyanobacterium P. agardhii, was isolated from Lake Donghu, Wuhan, China. PaV-LD only lysed P. agardhii strains isolated from Lake Donghu and not those isolated from other lakes. The PaV-LD particle has an icosahedral, non-tailed structure, ca. 70 to 85 nm (mean +/- SD = 76 +/- 6 nm) in diameter. PaV-LD was stable at freezing temperature, but lost its infectivity at temperatures >50 degrees C. Lysis of host cells was delayed about 3 d after the PaV-LD treatment with chloroform, and the virus was inactivated by exposure to low pH (<= 4). The latent period and burst size of the PaV-LD were estimated to be 48 to 72 h and about 340 infectious units per cell, respectively. The regrowth cultures of surviving host filaments were not lysed by the PaV-LD suspension. To our knowledge, this is the first isolation and cultivation of a virus infectious to the filamentous bloom-forming cyanobacterium Planktothrix from a freshwater lake.

Detection of the hepatotoxic microcystins in 36 kinds of cyanobacteria Spirulina food products in China

Gel filtration chromatography, ultra-filtration, and solid-phase extraction silica gel clean-up were evaluated for their ability to remove microcystins selectively from extracts of cyanobacteria Spirulina samples after using the reversed-phase octadecylsilyl ODS cartridge for subsequent analysis by liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS). The reversed-phase ODS cartridge/silica gel combination were effective and the optimal wash and elution conditions were: H2O (wash), 20% methanol in water (wash), and 90% methanol in water (elution) for the reversed-phase ODS cartridge, followed by 80% methanol in water elution in the silica gel cartridge. The presence of microcystins in 36 kinds of cyanobacteria Spirulina health food samples obtained from various retail outlets in China were detected by LC-MS/MS, and 34 samples (94%) contained microcystins ranging from 2 to 163 ng g(-1) (mean=1427 ng g(-1)), which were significantly lower than microcystins present in blue green alga products previously reported. MC-RR-which contains two molecules of arginine (R)-(in 94.4% samples) was the predominant microcystin, followed by MC-LR-where L is leucine-(30.6%) and MC-YR-where Y is tyrose-(27.8%). The possible potential health risks from chronic exposure to microcystins from contaminated cyanobacteria Spirulina health food should not be ignored, even if the toxin concentrations were low. The method presented herein is proposed to detect microcystins present in commercial cyanobacteria Spirulina samples.

Estimation of the detection probability for Yangtze finless porpoises (Neophocaena phocaenoides asiaeorientalis) with a passive acoustic method

Yangtze finless porpoises were surveyed by using simultaneous visual and acoustical methods from 6 November to 13 December 2006. Two research vessels towed stereo acoustic data loggers, which were used to store the intensity and sound source direction of the high frequency sonar signals produced by finless porpoises at detection ranges up to 300 m on each side of the vessel. Simple stereo beam forming allowed the separation of distinct biosonar sound source, which enabled us to count the number of vocalizing porpoises. Acoustically, 204 porpoises were detected from one vessel and 199 from the other vessel in the same section of the Yangtze River. Visually, 163 and 162 porpoises were detected from two vessels within 300 m of the vessel track. The calculated detection probability using acoustic method was approximately twice that for visual detection for each vessel. The difference in detection probabilities between the two methods was caused by the large number of single individuals that were missed by visual observers. However, the sizes of large groups were underestimated by using the acoustic methods. Acoustic and visual observations complemented each other in the accurate detection of porpoises. The use of simple, relatively inexpensive acoustic monitoring systems should enhance population surveys of free-ranging, echolocating odontocetes. (C) 2008 Acoustical Society of America.

Enzyme-linked immunosorbent assay of changes in serum levels of growth hormone (cGH) in common carps (Cyprinus carpio)

The aim of the present study was to purify the common native carp growth hormone (ncGH), produce monoclonal antibodies (mAbs) to common native carp growth hormone (ncGH), and further enhance the sensitivity of enzyme-linked immunosorbent assays (ELISA) for ncGH. Additionally, we investigated changes in serum ncGH levels in carps raised in different environmental conditions. The recombinant grass carp (Ctenopharyngodon idella) growth hormone was purified and used as antigen to immunize the rabbit. The natural ncGH was isolated from the pituitaries of common carp. SDS-PAGE and Western blot utilizing the polyclonal anti-rgcGH antibody confirmed the purification of ncGH from pituitaries. Purified ncGH was then used as an immunogen in the B lymphocyte hybridoma technique. A total of 14 hybridoma cell lines (FMU-cGH 1-14) were established that were able to stably secrete mAbs against ncGH. Among them, eight clones (FMU-cGH1-6, 12 and 13) were successfully used for Western blot while nine clones (FMU-cGH 1-7, 9 and 10) were used in fluorescent staining and immunohistochemistry. Epitope mapping by competitive ELISA demonstrated that these mAbs recognized five different epitopes. A sensitive sandwich ELISA for detection of ncGH was developed using FMU-cGH12 as the coating mAb and FMU-cGH6 as the enzyme labeled mAb. This detection system was found to be highly stable and sensitive, with detection levels of 70 pg/mL. Additionally, we found that serum ncGH levels in restricted food group and in the net cage group increased 6.9-and 5.8-fold, respectively, when compared to controls, demonstrating differences in the GH stress response in common carp under different living conditions.

Dietary methionine requirement for juvenile rockfish, Sebastes schlegeli

A 65-day growth trial was conducted at 19.5 degrees C to determine the optimal dietary methionine for juvenile rockfish, Sebastes schlegeli. Semipurified diets were formulated to be isonitrogenous and isoenergetic. Fish meal was used as intact protein source and crystal amino acid was used as a part of dietary protein. Six experimental diets were formulated to contain 5.8, 10.8, 15.8, 20.8, 25.8 and 30.8 g kg(-1) dietary methionine. The results showed that dietary methionine significantly affected specific growth rate, weight gain, food conversion ratio, protein productive value (PPV), energy retention efficiency, carcass index and body composition. No significant difference was found in hepatosomatic index. The dietary methionine requirement for maximum growth was 13.7 g kg(-1) dry matter or 28.0 g kg(-1) of dietary protein when cystine content was 1.2 g kg(-1) dry matter.

Mutations stabilize small subunit ribosomal RNA in desiccation-tolerant cyanobacteria Nostoc

The ribosomal RNA molecule is an ideal model for evaluating the stability of a gene product under desiccation stress. We isolated 8 Nostoc strains that had the capacity to withstand desiccation in habitats and sequenced their 16S rRNA genes. The stabilities of 16S rRNAs secondary structures, indicated by free energy change of folding, were compared among Nostoc and other related species. The results suggested that 163 rRNA secondary structures of the desiccation-tolerant Nostoc strains were more stable than that of planktonic Nostocaceae species. The stabilizing mutations were divided into two categories: (1) those causing GC to replace other types of base pairs in stems and (2) those causing extension of stems. By mapping stabilizing mutations onto the Nostoc phylogenetic tree based on 16S rRNA gene, it was shown that most of stabilizing mutations had evolved during adaptive radiation among Nostoc spp. The evolution of 16S rRNA along the Nostoc lineage is suggested to be selectively advantageous under desiccation stress.

Sonar gain control in echolocating finless porpoises (Neophocaena phocaenoides) in an open water (L)

Source levels of echolocating free-ranging Yangtze finless porpoise (Neophocaena phocaenoides asiaeorientalis) were calculated using a range estimated by measuring the time delays of the signals via the surface and bottom reflection paths to the hydrophone, relative to the direct signal. Peak-to-peak source levels for finless porpoise were from 163.7 to 185.6 dB re:1 mu Pa. The source levels are highly range dependent and varied approximately as a function of the one-way transmission loss for signals traveling from the animals to the hydrophone. (c) 2006 Acoustical Society of America.

Acrossocheilus spinifer, a new species of barred cyprinid fish from south China (Pisces : Teleostei)

Acrossocheilus spinifer sp. nov. is described from the river basins in Fujian Province and the Han Jiang basin in Guangdong Province, south China. It is one of the barred Acrossocheihis species sharing five or six vertical bars on the flanks, with each bar being two scales in width. Acrossocheilus spinifer sp. nov. is morphologically most similar to Acrossocheilus wenchowensis. but distinguished from it by: a colour pattern of all vertical bars extending ventrally to the second scale row below the lateral line, and having the second bar placed posterior to the base of the last simple dorsal-fin ray, a blunt snout; and a stout, last simple dorsal-fin ray. Acrossocheilus spinifer sp. nov. resembles Acrossocheilus kreyenbergii and Acrossocheilus stenotaeniatus with which it shares a stout, last simple dorsal-fin ray with a serrated posterior edge, but is separated from both species by having a narrow median interruption in the lower lip, a lower jaw fully covered by the lower lip when viewed ventrally and the second vertical bar placed posterior to the base of the last simple dorsal-fin ray. The absence of a longitudinal stripe extending along the lateral line on the flanks in males readily distinguishes A. spinifer sp. nov. from Four other species, namely Acrossocheilus fasciatus, Acrossocheilus paradoxus, Acrossocheilus parallens, and Acrossocheilus jishouensis. (c) 2006 The Authors Journal compilation (c) 2006 The Fisheries Society of the British Isles.