胡子鲇的人工繁殖

<正> 胡子鲇(Clarias fuscus)俗称塘虱(广东)、塘角鱼(广西)、土虱(台湾、闽南)。关于胡子鲇的人工繁殖,黄绍勤等(1964),韩传英等(1978),都获得成功,但催产率、受精率、孵化率,特别是培苗的成活率都比较低。作者于1979年进行了胡子鲇的人工繁殖和胚胎发育观察,现把试验和观察结果综述如下。     

胡子鲇、革胡子鲇及其杂交子1代的耗氧规律

鱼类的耗氧率和窒息点,是反映鱼体能量代谢的重要生理指标,也可作为良种选育时的性状指标之一。同时,可以估算鱼类单位水体的容纳量和运输密度以及鱼类的需饵量。因此,研究鱼类的耗氧规律,在理论上和养殖生产上都有很大的意义。有关鱼类耗氧规律的资料报道很多［１～...     

盐度对胡子鲇、革胡子鲇及其杂交子一代胚胎发育的影响

胡子鲇、革胡子鲇及其杂交子一代珠胡子鲶胚胎发育各期的存活率和孵化率均随着盐度的升高而降低,该类鱼胚胎发育的环境盐度以不超过５为宜;发育至孵化期胚胎所能耐受的最高盐度革胡子鲇是１０,胡子鲇和珠胡子鲇是１１。盐度对３种胡子鲇胚胎发育速度影响不大,总的趋势是随着盐度的升高而变慢。     

革胡子鲇人工繁殖技术

革胡子鲇属热带淡水鱼类,有生长快,耐低氧,抗病力强,产量高,饲料来源广等优点。是深受养殖户喜爱的优良品种之一。为帮助广大养殖户掌握人工繁殖技术,现简介如下:1 繁殖习性:革胡子鲇一冬龄后,体长12厘米以上就有繁殖力。雌鱼一年内可产卵2—4次;雄鱼在整个繁殖期都有繁殖力,无明显周期性变化。每年春天水温达到18℃以上就进入繁殖     

革胡子鲇秋季繁殖及鱼种越冬试验

用HCG500国际单位／kg LRH-A220μ g/kg，于1994年秋季人工催产革胡子站33组。雌雄比例为1：1。产卵34万粒，孵化鱼苗21．5万尾。鱼种越冬成活率90％以上。     

池塘主养胡子鲇试验

以野杂鱼为饵料，池塘主养胡子鲇，并搭配一定比例的花白鲢和罗非鱼调节水质。亩产成鱼845kg，亩纯利润2300元。     

网箱养殖革胡子鲇

1995年郸城县渔场利用池塘水域资源置网箱2只,总面积为50平方米进行胡子鲇养殖。共投放鱼种4100尾,经4个月饲养管理,收获胡子鲇成鱼3520尾,总产量4210千克,成活率达86％,个体规格为1～1.5千克,产值2.98万元,除去各种费用,纯收入1.87万元,经济效益显著。其养殖技术要点简介如下:1 池塘条件:水源充足,水质良好,溶氧量高,饵料生物丰富。池塘面积为0.6公顷,平均水深2米,池底淤泥少。     

麻塘试养胡子鲇初获成功

广东省东莞县万江公社盛产黄麻、每年要用很多鱼塘浸洗黄麻，可是浸洗黄麻的鱼塘，水质变黑，无法再养鱼。为了使浸洗过黄麻的鱼塘能再利用，他们试养了耐氧、耐肥和生命力强的胡子鲇。1979年8～9月，分别在新和、胜利等大队，利用麻塘进行试养，获得了成功。     

池塘单养革胡子鲇高产试验

近年来,濮阳县掀起养殖革胡子鲇热潮,但大都因苗种问题和养殖后期饲料难以解决,致使养成规格较小,产量不高、效益不佳。我站于1998年在庆祖渔场总面积为6.7亩的三个池塘及1999年在庆祖渔场和胡状石槽村总面积为14.5亩的五个池塘内,进行了利用冷冻鸡肠喂养革胡子鲇高产试验,亩产超过5000公斤,最高亩利润达1.6万元。现将试验情况总结如下:     

胡子鲇人工繁殖技术

胡子鲇,俗称塘鲺,土鲺,滑哥,角鱼,是产粘性卵的鱼类。在分类上属硬骨鱼纲,鲇形目,胡子鲇科,胡子鲇属。分布于热带、亚热带,营养丰富,具有药用价值。现将本人多年来从事胡子鲇人工繁殖生产工作,总结如下,提供参考。     

草鱼淋巴器官中的肥大细胞

通过组织化学与形态学研究首次在草鱼的胸腺和头肾等淋巴器官中证实了肥大细胞的存在。草鱼肥大细胞的染色性质在某些方面似乎类似于哺乳动物的粘膜肥大细胞。Carnoy氏液及阿尔新蓝分别是优良的固定剂及染料，而中性缓冲甲醛却完全阻断草鱼肥大细胞的着染。值得注意的是一些曾被用于鉴定硬骨鱼肥大细胞(或嗜酸性颗粒细胞)的组织化学技术在本研究中未能检出草鱼肥大细胞。电镜下证实，草鱼肥大细胞中含有大量特征性的胞浆颗粒，其中充满无定形颗粒状基质，基质电子密度有的较高，有的较低，但未见特殊的亚微结构。     

硬骨鱼肥大细胞的研究进展

有关肥大细胞，在某些啮齿动物及人类中研究已比较深入，但在鱼类及其他低等脊椎动物中研究较少。硬骨鱼(teleostean fish)肥大细胞(MC)，常被称为嗜酸性颗粒细胞(EGC)，或肥大细胞／嗜酸性颗粒细胞(MC／EGC)，本文对有关研究进展作一综述并对硬骨鱼肥大细胞的发生、组织化学性质、细胞颗粒介质及其在鱼类健康与疾病中可能的功能意义等进行讨论，旨为深入研究鱼类重大疫病的发生机理提供基础依据。     

鲟鱼硫酸软骨素对小鼠免疫器官肥大细胞的影响

为研究鲟鱼硫酸软骨素对小鼠免疫器官的影响,连续对小鼠灌胃不同剂量鲟鱼硫酸软骨素2周后,外科手术取出胸腺和脾脏,并依次进行称重、卡洛氏固定、石蜡包埋、组织切片、甲苯胺蓝染色,40倍物镜下观察鲟鱼硫酸软骨素对小鼠免疫器官肥大细胞数量的影响。结果表明：鲟鱼硫酸软骨素能促进小鼠免疫器官重量指数增大,并能显著促进免疫器官中肥大细胞数量的增长。其中,600 mg/kg剂量下小鼠胸腺指数显著( P<0．05)增大,胸腺中肥大细胞数量极显著( P<0．01)增加,60 mg/kg剂量下小鼠脾脏重量的增加最为明显( P<0．01),6 mg/kg剂量下小鼠脾脏中肥大细胞数量的增加最为明显( P<0．01)。     

左旋咪唑对胡子鲶头肾和脾脏显微及亚显微结构的影响

胡子鲶投喂0,300mg/kg盐酸左旋咪唑的日粮1周,在停喂后第4周和第8周,取头肾和脾脏制作组织切片,第6周取头肾和脾脏制作透射电镜切片。结果表明:左旋咪唑可以刺激胡子鲶脾脏和头肾白细胞特别是淋巴细胞的增生,其中嗜中性白细胞的功能状态较对照组活跃。     

胡子鲇脑型芳香化酶基因全长cDNA克隆及表达

采用RT-PCR和RACE法,克隆了胡子鲇(Clarias fuscus)脑型芳香化酶基因Cyp19a1b,应用荧光实时定量PCR检测其在前脑、下丘脑、脑垂体、肝、精巢和卵巢6种组织,以及性腺分化前后(出膜后12～30 d)全鱼中的mRNA表达。结果表明,Cyp19a1b cDNA全长2 347 bp,5′端非编码区219 bp,3′端[不包括poly(A)]596 bp,开放阅读框(ORF)1 503 bp,编码500个氨基酸,推测其编码蛋白质分子量为56.388 kD。序列分析及分子系统进化树结果表明,胡子鲇Cyp19a1b氨基酸序列与非洲鲇(Clarias gariepinus)Cyp19a1b同源性最高,达95.6%;与南方大口鲇(Silurusmeridionalis)、黄颡鱼(Pelteobagrus fulvidraco)、斑马鱼(Danio rerio)、斑点叉尾(Ictalurus punctatus)、赤点石斑鱼(Epinephelus akaara)、鲤(Cyprinus carpio)、鲫(Carassius auratus)及稀有鲫(Gobiocypris rarus)Cyp19a1b同源性达75%以上,但与上述鱼类的性腺型芳香化酶基因(Cyp19a1a)同源性低于62%,表明其为脑型芳香化酶,同源性分析结果与根据传统形态学和生化特征分类的结果相一致。荧光实时定量PCR结果显示,Cyp19a1b在胡子鲇上述组织中均有表达,其中下丘脑中表达量最高,肝和精巢最低,在脑部的表达存在明显的性别差异(P<0.05)。此外,在胡子鲇性腺分化前(出膜后12 d)Cyp19a1b即开始表达,但分化前后表达量无显著性差异(P>0.05)。结果暗示Cyp19a1b可能不是引起胡子鲇性腺分化的直接因素,但其可能通过"下丘脑垂体性腺轴"对性腺分化过程产生间接影响。     

芳香化酶抑制剂来曲唑对胡子鲇性腺分化及相关基因表达的影响

采用组织学和荧光实时定量PCR方法, 检测饲喂不同剂量芳香化酶抑制剂来曲唑(letrozole, 50、100和200 μg/g)对胡子鲇(Clarias fuscus)性腺组织学和性别比率的影响, 以及200 μg/g 来曲唑对性分化前后脑型芳香化酶基因(Cyp19a1b)和翼状螺旋/叉头转录因子2(Foxl2)基因表达的影响, 结果表明, 50 μg/g 剂量的来曲唑对胡子鲇性腺分化无显著影响; 但100 μg/g和200 μg/g剂量的来曲唑可促进胡子鲇精巢分化, 抑制卵巢分化, 卵巢腔最早出现时间和初级卵母细胞出现时间均分别推迟3 d和6 d, 而初级精母细胞最早出现时间则分别提前2 d和5 d, 且雄性率分别达65.8%和71.3%, 显著高于50 μg/L组和对照组(P<0.05)。胡子鲇性腺分化前(出膜后12 d), Cyp19a1b和Foxl2基因即开始表达, 性腺分化前后Cyp19a1b相对表达量无显著差异(P>0.05), 但Foxl2相对表达量则随性分化而逐渐降低, 且来曲唑显著抑制性腺分化过程中Cyp19a1b和Foxl2的表达(P<0.05)。结果表明, 100 μg/g 以上剂量的来曲唑可有效诱导胡子鲇分化为雄性; Cyp19a1b可能不直接参与胡子鲇性腺分化, 但Foxl2直接参与此过程。     

3种硬骨鱼类消化道肥大细胞的组织化学与免疫组化

类胰蛋白酶己被作为人类和某些哺乳动物组织中肥大细胞的标志。为检测鱼类肥大细胞胞浆中是否含有类胰蛋白酶,采用小鼠抗人类肥大细胞类胰蛋白酶单克隆抗体AA1通过Elivision^TM plus免疫组化染色技术,对尼罗罗非鱼、日本鳗鲡和欧洲鳗鲡消化道组织以及人胃癌组织石蜡切片中的肥大细胞进行染色,同时应用AB/SO和改良甲苯胺蓝法进行组织化学染色。结果表明,应用AB/SO和改良甲苯胺蓝染色都能较好显示尼罗罗非鱼肥大细胞, AB/SO染色法对日本鳗鲡和欧洲鳗鲡效果较差,改良甲苯胺蓝染色在上述两种鱼中未能检出肥大细胞;采用小鼠抗人类肥大细胞类胰蛋白酶单克隆抗体AA1通过Elivision^TMplus免疫组化染色技术,首次证实了尼罗罗非鱼肥大细胞胞浆中类胰蛋白酶的存在,但类胰蛋白酶阳性细胞数量很少,主要分布于尼罗罗非鱼消化道各段的黏膜上皮细胞基部和黏膜固有层,而日本鳗鲡与欧洲鳗鲡消化道均未检出类胰蛋白酶阳性细胞。说明不同鱼类肥大细胞胞浆颗粒中生物化学组分存在差别。人胃癌间质中可见多量类胰蛋白酶阳性细胞。     

Liver of the fish Gymnotus inaequilabiatus and nematode larvae infection: Histochemical features and expression of proliferative cell nuclear antigen

Histopathological lesions due to third‐larval stage of nematode Brevimulticaecum sp. within the liver of a subpopulation of 31 Gymnotus inaequilabiatus from the Pantanal Region (Brazil) were studied with histochemical and immunohistochemical methods. In 93.5% of fish, livers harboured nematode larvae and the intensity of infection ranged from 8 to 293. In livers with highest number of larvae, the hepatic tissue was occupied primarily by the nematodes. Each larva was encircled by focal inflammatory granulomatous reaction. Within the thickness of the granuloma, three concentric layers were recognized: an inner layer of densely packed epithelioid cells, a middle layer of mast cells (MCs) entrapped in a thin fibroblast‐connective mesh and an outer layer of fibrous connective tissue with fibroblasts. Epithelioid cells and fibroblasts within the thickness of the granuloma wall were positive for proliferative cell nuclear antigen (PCNA). Moreover, several hepatocytes in infected liver were immunoreactive to PCNA. Occurrence of rodlet cells and MCs in parenchyma, in close proximity to the encysted nematode larvae and near the blood vessel of infected liver, was observed. Macrophage aggregates (MAs) were numerous within the granulomas and scattered in parenchyma of the infected liver. High quantity of haemosiderin was encountered in MAs and hepatocytes of infected liver.     

Discards from the commercial gillnet fishery for dusky flathead, Platycephalus fuscus, in New South Wales, Australia: spatial variability and initial effects of change in minimum legal length of target species

A scientific observer programme was used to quantify the composition and magnitude of discards in the gillnet fishery for dusky flathead, Platycephalus fuscus (Cuvier), in three barrier estuaries in New South Wales, Australia, during the 2001 fishing season. Regulations only permit the retention of legal‐sized dusky flathead and legal‐sized blue swimmer crab, Portunus pelagicus L., and mud crab, Scylla serrata (Forskål); all other organisms were discarded. Sampling was stratified into two time periods; before and after 1 July 2001 which coincided with the increase in the minimum legal length (MLL) of dusky flathead from 33 to 36 cm total length (TL). Eighty one catches were sampled, yielding 38 finfish species and two portunid crab species. Legal‐sized dusky flathead were the most abundant organism captured, accounting for 23–47% by number and 34–54% by weight of the mean observed catch depending on the estuary and survey period, with a mean catch of 25–59 flathead weighing 13–25 kg per fishing‐night. Species composition and relative abundance of catches differed among estuaries, but not between sampling periods. Predominant bycatch species included legal and undersize blue swimmer crab, sea mullet, Mugil cephalus L., luderick, Girella tricuspidata (Quoy & Gaimard), bream, Acanthopagrus australis (Günther) and yellowfin leatherjacket, Meuschenia trachylepis (Günther). These five species accounted for 82% of total bycatch by number and 71% by weight, pooled across the three estuaries. More crabs were retained than discarded, with retained legal‐size crabs (byproduct) accounting for 16% of total bycatch by number and 13% by weight, with an average of 5–22 crabs weighing 1–6 kg being caught per fishing‐night, depending on the estuary. Overall, 7% of dusky flathead captured (number) were below the MLL of 36 cm and discarded, suggesting the nets as currently configured may be relatively selective in catching legal‐size flathead. However, 41% of dusky flathead were <40 cm TL, indicating that if the MLL for this species is increased to this length as proposed, new nets must be introduced into the fishery. The findings are discussed in terms of making the flathead fishery more sustainable, including alternative management strategies for the fishery.