基于天然XY雌鱼培育YY超雄尼罗罗非鱼的新方法

前期报道了养殖群体存在天然XY雌鱼,但其能否用于培育YY超雄罗非鱼尚不清楚。本研究首先引入遗传性别受LG23染色体严格控制的CQ(重庆)尼罗罗非鱼群体和具有天然XY雌鱼的WC(湛江吴川)群体,将CQ群体XY雄鱼与WCXY雌鱼杂交,检验杂交F₁ YY超雄鱼是否可用于控制后代性别,并比较杂交F₁ XY和YY罗非鱼体质量、性腺指数、血清激素水平和性腺基因表达情况。研究发现,CQXY雄鱼和WCXY雌鱼交配,获得的F₁中有25%为YY超雄鱼,经鉴定为全雄且可育。将F₁ YY超雄鱼与WC XX雌鱼、WC XY雌鱼(母本)、杂交F₁ XX雌鱼和CQ XX雌鱼交配,后代几乎全雄,仅在与F₁ XX雌鱼交配的后代中有2尾雌鱼(雄性率98%)。在孵化后180 d,杂交F₁中XY和YY个体的体质量、性腺指数、血清激素水平差异不显著。基因表达分析发现,YY鱼精巢中AmhX/AmhY mRNA表达显著高于XY鱼,而Dmrt1和Cyp11b2 mRNA表达水平差异...     

提高杂交鲤制种技术试验

为了充分发挥我场杂交鲤制种优势 ,自１９９５年至１９９９年 ,我们集中力量 ,进行了杂交鲤制种生产试验 ,孵化出售杂交鲤水花鱼苗６５８０万尾 ,其中 :芙蓉鲤４２３０万尾 ,三杂交鲤２１５０万尾 ,年均出苗１３１６万尾 ,经济效益良好。现将试验报告如下。１材料１．１种鱼来源芙蓉鲤 ,以黑龙江水科所花浦试验场的散鳞镜鲤雌鱼为母本 ,以江西省兴国县红鲤原种场的兴国红鲤雄鱼为父本 ,进行杂交组合 ;三杂交鲤 ,本场自制的芙蓉鲤商品后代中四次选育出的雌鱼为母本 ,益阳资江内的正宗资江野鲤雄鱼为父本 ,进行杂交组合 ;丰鲤用本场引进繁殖原…     

温台渔场日本鲭的繁殖生物学特征

利用2012年春季在温台渔场对日本鲭(Scomber japonicus)繁殖群体连续6批取样的生物学测定数据,对其繁殖生物学特征进行了研究。结果表明,叉长340 mm以下群体中,雌雄比基本符合1∶1的性比关系;叉长340 mm以上群体中,雌鱼显著多于雄鱼(P0.05)。GSI随时间的变化结果显示,温台渔场日本鲭的主要繁殖期为3月中旬至4月中旬;不同时间段的雌鱼和雄鱼GSI均总体表现为雌鱼大于雄鱼(P0.05)。不同性腺发育阶段的平均摄食强度总体表现为雄鱼大于雌鱼。不同性腺发育阶段的雌性和雄性的肝指数均雌性显著大于雄性(P0.05)。绝对繁殖力范围为44 017~734 684粒/尾,平均值为(173 867±15 719)粒/尾,优势组为(10~30)×104粒/尾,占70.37%;相对繁殖力范围为187~1 403粒/g,平均值为(538±31)粒/g,优势组为(390~700)粒/g,占66.67%。卵径范围为0.27~1.22 mm,平均值为(0.86±0.01)mm,优势组为0.7~1.1 mm。温台渔场日本鲭的绝对繁殖力低于黄海北部而高于台湾海峡,相对繁殖力高于历史水平,平均卵径小于20世纪80年代,雌雄鱼的最小性成熟叉长均有一定程度的降低。以上结果都说明日本鲭为应对高强度捕捞和环境胁迫压力而采取增加相对繁殖力、减小卵径、提早性成熟等繁殖策略来维持种群数量和保证种群的延续。     

瓣结鱼生物学特性及生殖力的研究

对从皖南山区河流中采集到瓣结鱼活体样本进行体长、体重测定,通过鳞片鉴定其年龄,研究其性腺发育及繁殖力。结果表明:瓣结鱼体长与体重呈指数函数相关,W=0.0182L~b,b=2.9949;绝对怀卵量6680~38704粒,平均24543粒;雌鱼成熟系数0.74~31.47,平均20.31,雄鱼成熟系数0.18~7.43,平均2.17;体长的相对繁殖力:y=789.19x-918.15,经计算得出体长相对繁殖力(F_M)为760.9粒/cm。     

三种红鲤生长性状的杂种优势与遗传相关分析

对兴国红鲤、荷包红鲤、瓯江彩鲤及其双列杂交种(F1)在成鱼阶段的体重和10个形态性状的杂种优势和遗传相关分析发现:(1)兴国红鲤×荷包红鲤杂交,表现出显著的平均杂种优势和超亲优势;兴国红鲤×瓯江彩鲤杂交、荷包红鲤×瓯江彩鲤杂交的平均杂种优势不明显,也未表现出超越瓯江彩鲤亲本的超亲杂种优势;(2)体重与全长、体长之间加性相关显著(rA>0.9),但显性相关不显著;全长与体长、全长与尾柄长、体长与尾柄长的加性相关及显性相关均显著(rA>0.9;rD>0.9);全长、体长与体高、尾柄高间均呈显著负加性相关(rA<-0.9);体高与尾柄长呈显著负加性相关(rA=-0.896),体高与尾柄高呈显著正加性相关(rD=0.970)。     

框鳞镜鲤♀X团头鲂♂杂种F1与亲本性腺组织学比较研究

鱼类亚科间杂交组合的受精生物学如受精率、孵化率、胚胎畸形率,胚胎从受精至孵化出膜所需时间,后代1~2龄鱼的生长情况等以及杂交F1的可育性的研究表明,鱼类亚科间杂种不育不是绝对的。虽然如草鱼♀×长春鳊♂杂种F1为三倍体,其性腺不发育;草鱼♀×团头鲂♂杂种F1有性腺存在,但发育很差,是不育的;草鱼♀×花鲢♂杂种F1,Marian等人从染色体观察是三倍体,性腺不育,但鳙♀×草鱼♂杂种F1近似母本的雌性鱼可以达到性成熟,并连续进行了3年人工繁殖;红眼鱼♀×拟鳊♂杂种F1部分雌鱼可育,而雄鱼发育很差,但从个别个体可以取得精液,并获得了后代…     

神农架多鳞铲颌鱼繁殖生物学研究

研究了神农架多鳞铲颌鱼的繁殖生物学。生殖季节可凭"珠星"等副性征辨别雌雄,首次性成熟年龄雌鱼为3龄、雄鱼为2龄;雌雄性比为1.08∶1。繁殖期为每年的4月底至6月中旬,属多次性产卵类型。个体绝对繁殖力为1527~15875粒,平均为(5568±3172)粒;个体相对繁殖力为11~41粒/g,平均值为(27.14±7.46)粒/g。     

吉奥罗非鱼苗种繁育技术

正一、亲本选择与培育1.亲本来源母本来自上海海洋大学等选育的"新吉富"罗非鱼群体,筛选形态特征明显和经济性状显著的雌鱼作母本,总选留率80%;父本源于奥利亚罗非鱼,筛选形态特征明显和经济性状显著的雄鱼作父本,总选留率7.5%。繁殖吉奥罗非鱼亲鱼的初始繁育年龄、体重和使用年限要符合表1的要求。     

彩鲫与建鲤杂交 F1代形态特征研究

采用全红体色日本彩鲫（ Carassius auratus）与青灰色建鲤（ Cyprinus carpiovar Jian）杂交,对所获得鲤鲫F1（建鲤♀×彩鲫♂）和鲫鲤F1（彩鲫♀×建鲤♂）两个杂交群体的个体及其父母本的外形特征进行研究,从而了解建鲤与彩鲫正反交后代的形态特征。试验分别从大学实验室随机取样50尾,对体型指数、可量性状、可数性状和肥满度分析比较。在体型指数体长/全长中,鲫鲤F1偏向母本,而在体高/体长中,鲤鲫 F1偏向母本;头高/体高、头高/头长、尾柄长/尾柄高都偏向建鲤,头长/体长这一体型指数处于亲本之间,属于杂交性状。进而推测生长性能出现离散现象,控制体色的基因来自母本。     

康拉克湖区叶尔羌高原鳅繁殖特性的初步研究

试验研究了康拉克湖区叶尔羌高原鳅的繁殖特性,包括雌、雄鱼的外部特征和内部构造及繁殖习性。雌雄鱼从体型、胸鳍形态上均有所不同;卵巢为单一囊状,以1根输卵管通到泄殖孔;精巢分为左右两叶,表面光滑无皱褶;成熟卵的颜色为浅黄色,粘性,沉性卵。生殖高峰期在5月中旬到6月底。成熟雌鱼性成熟系数高,平均35.23,最高达67.83。回归分析显示,繁殖群体全长与体质量呈极显著的幂函数关系;绝对繁殖力与全长、体重呈正相关;相对繁殖力、成熟系数与全长和体质量不存在显著的函数关系。     

Rare serotype occurrence and PFGE genotypic diversity of Streptococcus agalactiae isolated from tilapia in China

Previously, we reported 10 PEGE types of 85 tilapia Streptococcus agalactiae(GBS), which shifted from Streptococcus iniae in China, by using PEGE method. Presently, larger and more representative tilapia GBS were isolated, for the ?rst time in China, to characterize their serotypes and genetic diversities more precisely than had done before. 168 GBS strains were distributed in ?ve provinces of China, in which Guangdong, Guangxi and Hainan were the major ones, holding36.9%(62/168), 37.5%(63/168) and 19.6%(33/168), respectively. Serotypes, Ia, Ib and III, were observed in these strains and the most predominant one was Ia(95.2%), which mainly distributed in Guangdong, Guangxi and Hainan. Ia initially occurred in 2009, it shoot up to 32.1% in 2010,but decreased to 16.1% in 2011 before went up to 45.2% in 2012. Ib sporadically occurred during2007–2011, III onlyoccurred in 2012. 14 different PFGE types, including 4 new types(N, O,P and Q), were observed, in which B, D, F and G were the predominant types, holding 83.9%(141/168) of the total GBS strains. Ia corresponded to 11 PFGE types(A–H, N–P), in which type D predominated(51%). Ib represented 3 genotypes(I, J and Q) and III harbored only 2genotypes(N and F). Type N and Fsynchronously presented in Ia and III. In summary, the genetic diversity of tilapia GBS varied by serotypes and changed with geographical locations and years.Although Iastillpredominated, new rareserotypeIII alreadyoccurred in China.     

Growth hormone (GH) and reproduction: a review

Interaction between growth and reproduction occurs in many vertebrates and is particularly obvious at certain stages of the life cycle in fish. Endocrine interactions between the gonadotropic axis and the somatotropic axis are described, the potential role of GH being emphasised. A comparative analysis of these phenomena in mammals, amphibians and fish, suggests a specific role of GH in the physiology of puberty, gametogenesis and fertility. It also shows the original contribution made by studies on the fish model in this field of investigations.     

Purification and partial characterization of GtHs (cfLH and cfFSH) from Indian walking catfish (Clarias batrachus) (L.) and development of a homologous ELISA for cfLH

Two gonadotropins (GtH; Qa and Qb) were purified by gel filtration and ion exchange chromatography from the pituitaries of Indian walking catfish (Clarias batrachus). The presence of GtH during purification was assessed by in vitro oocyte maturation and in vivo steroidogenic activity, and their identities were determined by elution profiles, molecular weight, biological activities and yield. The molecular weights of Qa and Qb were 37 and 42 kDa, respectively, and composed of distinct subunits (Qa: 20 and 14 kDa and Qb: 26 and 18 kDa). Polyclonal antibodies raised against Qa immunostained Qa, Qb and pituitary GtH cells. A competitive Qa‐ELISA was developed whose sensitivity was 6.25 ng mL^?1 (1.25 ng well^?1) with intra‐ (3.5%) and inter‐ (12.4%) assay coefficients of variation. Displacement curves parallel to the standard were obtained with plasma and pituitary extracts of catfish, Qb and carp GtHII. The assay was validated by measuring the plasma Qa levels after LHRH treatment and in relation to ovarian growth in the female catfish during different reproductive phases. Based on the results, Qa and Qb corresponded to fish LH and FSH respectively. The findings will increase the knowledge of the mechanisms controlling fish reproduction and identification of sensitive phases in fish in captivity for hormonal manipulation.     

Controlled infection of Poecilia reticulata Peters (guppy) with Tetrahymena by immersion and intraperitoneal injection

Tetrahymena is a protozoan parasite, which infects guppy, Poecilia reticulata Peters, and causes substantial economical losses in commercial farms worldwide. Studies of guppy infected by Tetrahymena require standardized infection protocols. The LD50 for Tetrahymena infection of guppies by intraperitoneal (IP) injection was calibrated, and the level obtained was 946 parasites per fish. Guppy infection with Tetrahymena by immersion, imitating the natural route of infection via the integument, was studied under normal or stress conditions. Exposure to cold and netting (CNI) and to cold only (CI) followed by immersion exposure to 10 000 Tetrahymena per mL resulted in 22.5% and 19.2% mortality, respectively, as compared to 14.2% and 10% in groups that were netted only (NI) or non‐stressed (I). Histopathology revealed that immersion infection resulted in a systemic infection. Lysozyme levels, measured 3 weeks after infection, were significantly higher in the CNI group (288 μg per mg protein) compared with CI‐, NI‐ and I‐treated groups (94.5, 64 and 62.3 μg mg^?1, respectively). There was no evident parasite immobilization activity in body homogenates, suggesting no development of acquired immunity. Re‐infection by IP injection revealed no increase in protection in any of the treatment groups, mortality range of 56.3–75%, higher than in the non‐exposed control (40.6% mortality).     

Imported ornamental fish are colonized with antibiotic‐resistant bacteria

There has been growing concern about the overuse of antibiotics in the ornamental fish industry and its possible effect on the increasing drug resistance in both commensal and pathogenic organisms in these fish. The aim of this study was to carry out an assessment of the diversity of bacteria, including pathogens, in ornamental fish species imported into North America and to assess their antibiotic resistance. Kidney samples were collected from 32 freshwater ornamental fish of various species, which arrived to an importing facility in Portland, Oregon from Colombia, Singapore and Florida. Sixty‐four unique bacterial colonies were isolated and identified by PCR using bacterial 16S primers and DNA sequencing. Multiple isolates were identified as bacteria with potential to cause disease in both fish and humans. The antibiotic resistance profile of each isolate was performed for nine different antibiotics. Among them, cefotaxime (16% resistance among isolates) was the antibiotic associated with more activity, while the least active was tetracycline (77% resistant). Knowing information about the diversity of bacteria in imported ornamental fish, as well as the resistance profiles for the bacteria will be useful in more effectively treating clinical infected fish, and also potential zoonoses in the future.     

Effect of iodophor disinfection of non‐hardened Salmo trutta eggs on their bacterial and fungus load

This study investigated the efficiency of iodophor disinfection (135 ppm active iodine for 15–30 min) of non‐hardened Salmo trutta eggs against different groups of bacteria and against fungus. Egg samples were taken from non‐disinfected and from disinfected eggs, microorganisms were cultured on specific nutrient media and their mass was measured by turbidimetric methods. Bacteria and fungus mass of non‐hardened eggs could be reduced but not eliminated by iodophor disinfection with 135 ppm active iodine for 15 min. The extent of reduction was 47–65% (Experiment 1). The efficiency of disinfection increased with disinfection time as the reduction in bacteria and fungus mass was 40–55% after 15 min and 58–74% after 30 min (Experiment 2). Disinfection efficiency of iodophor solution diluted in water (reduction 49–57%) and of iodophor solution diluted in sodium chloride solution iso‐osmolar to the oocytes (reduction 52–61%) was similar (Experiment 3). The reduction in bacteria and fungus mass was persistent as it was 39–72% lower in embryos deriving from disinfected eggs than in embryos deriving from non‐disinfected ones (Experiment 4). In conclusion, the tested disinfection method is inadequate to eliminate pathogens completely but it could positively influence immune defence of eggs and embryos.     

Nitrogenous waste excretion and accumulation of urea and ammonia inChalcalburnus tarichi (Cyprinidae), endemic to the extremely alkaline Lake Van (Eastern Turkey)

The endemic, anadromous cyprinidChalcalburnus tarichi is the only fish species known to occur in alkaline Lake Van (Eastern Anatolia, Turkey). EightC. tarichi were maintained individually in Lake Van water (17 – 19°C; pH 9.8; 153 mEq·I^–1 total alkalinity; 22 total salinity) and tank water samples analyzed for 24 h in 2 to 4 h intervals. At zero time, < 1µM ammonia was present and urea was undetectable in the tank water; at 24 h, total ammonia and urea made up 114±32 and 35±25µM, respectively. Over the experimental period, ammonia-N and urea-N excretion averaged 1041±494 and 607±169moles·kg^–1 fish·h^–1, respectively. The extent of urea excretion was highly variable between specimens. Uric acid excretion was not detectable.Urea was present at high concentrations in all tissues and plasma (25 – 35moles·g^–1·ml^–1) of freshly caughtC. tarichi; total ammonia content of the tissues was by a factor of 1.9 (liver) to 3.0 (brain) lower. High arginase activity (2.4±0.2 U·min^–1·g^–1) was detected in the liver ofC. tarichi but ornithine carbamoylphosphate transferase, a key enzyme of the ornithine-urea-cycle, was absent. Ureagenesis is likely through degradation of arginine and/or uricolysis. High glutamine synthetase activity (11±0.6 U·min^–1·g^–1) and low ammonia content in brain suggest that, like other teleosts,C. tarichi has an efficient ammonia detoxification in the brain, but in no other tissue.Nitrogenous waste excretion at alkaline pH is discussed. The ability ofC. tarichi to excrete high levels of ammonia at extremely alkaline pH is unique among teleosts studied so far. The mechanism of ammonia excretion under Lake Van conditions remains to be elucidated.     

Influence of the antibacterial herbs, Solanum trilobatum, Andrographis paniculata and Psoralea corylifolia on the survival, growth and bacterial load of Penaeus monodon post larvae

The indiscriminate use of antibiotics and chemicals in shrimp hatcheries has led to biomagnification and that in turn could lead to rejection of a whole consignment. The application of the bioencapsulation technique as a tool for curative treatment in shrimp larvae was investigated. Herbs having antibacterial properties such as Solanum trilobatum, Andrographis paniculata and Psoralea corylifolia (methanolic extracts) were bioencapsulated in Artemia and fed to Penaeus monodon post larvae PL 1–25. The post larvae were reared in a medium inoculated with pathogenic bacteria such as Pseudomonas aeruginosa, Staphylococcus aureus, Salmonella typhi and Vibrio sp. Post larvae reared in the non-inoculated water and fed with non-enriched Artemia exhibited 90% survival, highest specific growth rate (12.43%) and reduced bacterial load. P. monodon reared in the bacterial inoculated water and fed with the non-enriched Artemia exhibited the lowest survival (10–30%), specific growth rate (8.42–9.1%) and increased bacterial load (2.86 × 10³ to 3.76 × 10⁵ cfu/g). The methanolic extracts of the herbs helped to increase survival and specific growth rate and reduced bacterial load in the P. monodon culture system. Among the three herbal extracts, P. corylifolia enriched Artemia fed post larvae showed the tendency to higher survival (>50%), growth rate (11.5 averaged) and low bacterial load (1.12 × 10⁵ cfu/g). This revised version was published online in August 2006 with corrections to the Cover Date.