斑鳢血细胞初步研究

对斑鳢的外周血细胞用常规Wright’s法染色并进行显微观察。结果显示,斑鳢外周血中具有红细胞、幼稚红细胞、小淋巴细胞、大淋巴细胞、血栓细胞、单核细胞和嗜中性粒细胞,未发现嗜酸性粒细胞和嗜碱性粒细胞。分别对各种血细胞的显微结构进行了描述。     

恒定和波动温度下丽斑麻蜥孵出幼体的表型变异

作者以丽斑麻蜥(Eremias argus)为模型动物研究恒定和波动孵化温度对孵化成功率和孵出幼体表型的影响。卵在四个恒定[24 ,27 ,30 and 33 (±0·3)℃]、一个波动温度下孵化。不同温度处理下的孵化成功率相同,但孵出幼体表型不同。孵化期随孵化温度升高呈指数式缩短;在相同平均温度下,波动温度孵化卵的孵化期比恒温孵化卵长。在所有被检表型特征中,幼体的干重、剩余卵黄干重和运动表现更易受孵化温度影响。总体而言,低温(24℃、27℃)孵出幼体运动表现最佳,高温(33℃)孵出幼体最差、温和温度(30℃和波动温度)孵出幼体居中。本文研究数据显示: (1)丽斑麻蜥卵每日短期暴露于潜在致死的极端温度下对孵化成功率和孵出幼体形态特征无明显的不利效应; (2)温度波动对孵出幼体运动表现无促进作用,对孵化期的影响则不同于平均值相同的恒定温度。     

Evaluation of genotoxic and oxidative stress response to dimethoate in freshwater fish Channa punctatus (Bloch)

Abstract

Dimethoate is one of the organophosphate insecticides widely used in agriculture throughout the world and is an inhibitor of cholinesterase in animals. The objective of the present study was to detect oxidative stress and DNA damage induced by dimethoate in the freshwater fish Channa punctatus (C. punctatus). The LC₅₀-96 h value of technical grade dimethoate was estimated at 19.10 μg L^-1 in a semi-static system and, on the basis of the LC₅₀ value, three concentrations were determined. The fish were exposed to these concentrations of dimethoate for 96 h and samplings were done at 24 and 96 h for assessment of oxidative stress and DNA damage. After exposure to dimethoate, the level of superoxide dismutase declined while lipid peroxidation, glutathione, induction of micronucleus and DNA damage were increased in C. punctatus as the concentration and exposure time increased. Thus our results suggest that dimethoate induces genotoxic effects which invariably accompanied and correlated with oxidative stress.     

乌鳢养殖对浮游动物群落结构的影响

通过对乌鳢(Channa argus)养殖池塘和对照水体即排水区和南阳湖的比较研究,探讨了乌鳢养殖对浮游动物群落结构的影响。研究表明,乌鳢养殖池塘的浮游动物物种数24种,密度1 032 ind/L,均明显低于周边水体(排水区64种,密度1 995 ind/L;近湖区65种,密度2 569 ind/L),而其生物量达4.65 mg/L,高于周边水体(排水区3.10 mg/L,近湖区2.85 mg/L),这主要是由于养殖池塘浮游动物生物量以枝角类、桡足类和无节幼体等大型浮游动物(95.70%)为主体,原生动物和轮虫所占比例(4.30%)相对较小,而周边水体则以原生动物和轮虫为主体;养殖池塘优势种为大型溞(Daphnia magna)和萼花臂尾轮虫(Brachionus calyciflorus),亦不同于周边水体的优势种;综合分析浮游动物优势种和多样性指数的评价结果,池塘水体呈中度污染,排水区水体呈轻度-中度污染,近南阳湖水域达到了轻度污染水平,这表明乌鳢养殖对周边水体造成了一定程度污染。     

Isolation and multiplex genotyping of polymorphic microsatellite DNA markers in the snakehead murrel, Channa striata

Seven polymorphic microsatellite loci were isolated and characterized for the snakehead murrel, Channa striata (Channidae), a valuable tropical freshwater fish species. Among 25 specimens collected from Kedah state in Malaysia, the number of alleles per locus ranged from 2 to 7. Observed and expected heterozygosities ranged from 0.120 to 0.880 and 0.117 to 0.698, respectively. A single locus (CS1-C07) was significantly deviated from Hardy-Weinberg equilibrium after Bonferroni correction. These novel markers would be useful for population genetic studies of the C. striata.     

Genotoxic and Mutagenic Assessment of Hexavalent Chromium in Fish Following In Vivo Chronic Exposure

Chromium is a well-documented carcinogen. To evaluate the genotoxic potential of hexavalent chromium on an aquatic bio-system, freshwater murrel fish (Channa punctatus) were exposed to potassium dichromate. The 96-h LC₅₀ for potassium dichromate was 61.80 mg/L for the test fish in a static system. On the basis of the 96-h LC₅₀, fish were exposed to sublethal concentrations of the test chemical. Fish exposed to the test chemical were sampled on days 1, 7, 14, 21, and 28 post-exposure and blood and gill cells were collected. Significantly (p < .05) higher DNA damage in both lymphocyte and gillcells and micronuclei formation in whole blood was observed at different test concentrations and sampling times of the test chemical as compared to control fish. The mean% tail DNA in the comet tail assay showed a concentration-dependent increase and the maximum% tail DNA was observed on day 7 of exposure in both cells. A similar trend was also observed in micronuclei induction in blood with maximum induction on day 21. Hexavalent chromium showed genotoxic potential in chronic exposure of C. punctatus, and the micronucleus test and the comet assay are the methods for sensitive and rapid detection of the genetic effects.     

Effect of meal size on the specific dynamic action of the juvenile snakehead (Channa argus)

The effect of meal size on the specific dynamic action (SDA) of the juvenile snakehead (Channa argus) was assessed at 25 °C. The fish were fed with test diets at meal sizes of 0.5, 1, 2, 3, 4, and 5% body mass and the postprandial oxygen consumption rate was determined at 1-h intervals until it returned to the pre-prandial level. The peak metabolic rate increased from 237.4 to 283.2 mg O₂ kg^− 1 h^− 1 as the relative meal size increased from 0.5% to 3% and leveled off at 4% and 5%. Factorial metabolic scope increased from 1.53 to 1.99 and SDA duration increased from 11.7 to 32.3 h as the relative meal size increased from 0.5% to 5%. The relationship between SDA duration (D) and relative meal size (M) was described as: D = 4.28 M + 10.62 (r² = 0.752, P < 0.05, n = 50). The energy expended on SDA increased while the SDA coefficient decreased with increasing meal size. The results of the present study suggest that the snakehead may adopt different feeding strategies when taking in different amounts of food.     

乌鳢产吲哚金黄杆菌的鉴定及其胞外产物特性分析

正乌鳢(Channa argus)俗称乌鱼、黑鱼、火头等,因其骨刺少,肉味鲜美,且具有去瘀生薪、生肌补血、滋补调养等多种生理功能,一直广受国内外消费者的亲睐。近十多年来,为顺应国内外贸易市场的需要,我国人工养殖乌鳢迅速发展。但由于高密度养殖、种质退化、环境恶化及人为因素干扰等多种原因,使得养殖乌鳢病害日趋增多,新的病原也不断出现。2013年5—6月,在浙江宁波部分乌鳢养殖池塘出现了批量死亡事件,病鱼主要症状为体表鳞片大面积脱落,有的烂眼、烂鳃、腹部膨胀、皮肤变黄并伴有少量体表出血现象;解剖发现其肝脏颜     

Chromosomal aberrations in a fish, Channa punctata after in vivo exposure to three heavy metals

The studies were designed to assess the extent of chromosomal aberrations (CA) under the exposure of three common heavy metalic compounds, viz. mercuric chloride, arsenic trioxide and copper sulphate pentahydrate, in vivo using fish, Channa punctata (2n = 32), as a test model. Prior acclimatized fishes were divided into five groups. Group I and II served as negative and positive control, respectively. An intramuscular injection of Mitomycin-C (@ 1 mg/kg body wt.) was administered to group II only. Fishes of groups III, IV and V were subjected to sublethal concentrations (10% of 96 h LC₅₀), of HgCl₂ (0.081 mg/L), As₂O₃ (6.936 mg/L) and CuSO₄·5H₂O (0.407 mg/L). Fishes of all the groups were exposed uninterrupted for 24, 48, 72, 96 and 168 h. Observations of kidney cells of exposed fishes revealed chromatid and chromosome breaks, chromatid and chromosome gaps along with ring and di-centric chromosomes. A significant increase over negative control in the frequency of chromosomal aberrations (CA) was observed in fish exposed to Mitomycin-C, Hg(II), As(III) and Cu(II). As the average ± SE total number of CA, average number of CA per metaphase and %incidence of aberrant cells in Hg(II) was 104.40 ± 8.189, 0.347 ± 0.027 and 10.220 ± 0.842, respectively; in As(III) 109.20 ± 8.309, 0.363 ± 0.027 and 10.820 ± 2.347, respectively and in Cu(II) 89.00 ± 19.066, 0.297 ± 0.028 and 8.900 ± 0.853, respectively. Hence, it reveals that the order of induction of frequency of CA was Cu < Hg < As. The findings depict genotoxic potential of these metals even in sublethal concentrations.     

金钱鱼体内惠州长宫吸虫种群动态分析

金钱鱼肠道内的惠州长宫吸虫,随着宿主体长的生长,其感染强度、平均丰盛度、平均拥挤度和宿主体长小于30mm的感染率呈逐渐增加的趋势,而宿主在不同体长组中,除了体长小于30mm以外,其感染率变化相对较稳定;在不同的月份中,吸虫在宿主体内的感染率从2月起呈逐渐下降趋势,感染强度则有逐渐增大倾向;平均丰盛度除从4～7月份有1个明显先上升后下降的变化外,其它月份变化差异不大。从吸虫在宿主体内的频率分布变化中,表明多数宿主不感染或只感染少量的吸虫,而少数宿主感染吸虫数量较大;吸虫种群在不同宿主体长组和不同月份的分布格局类型均为聚集分布,在不同宿主体长组中聚集分布强度随着种群密度增加而增强。