兰州鲇不同组织同工酶及群体遗传结构初步分析

采用聚丙烯酰胺凝胶电泳技术,分析了兰州鲇(Silurus lanzhouensis)肌肉、心脏、肝脏、脑、脾脏、肾脏和眼睛等7种组织中乳酸脱氢酶(LDH)、酯酶(EST)、苹果酸脱氢酶(MDH)、醇脱氢酶(ADH)、山梨醇脱氢酶(SDH)和谷氨酸脱氢酶(GDH)等6种同工酶的表达模式,并对各同工酶的酶谱进行了分析。结果表明:这6种同工酶在兰州鲇7种组织中的分布均存在明显的组织特异性;6种酶共记录出17个基因位点,其中EST-2、EST-3、MDH-3和SDH-2为多态位点;兰州鲇群体的多态位点比例P为23.53%,位点平均有效等位基因数Ne为1.24;平均观测杂合度和平均期望杂合度分别为0.137 2和0.105 1,Hardy-Weinberg遗传偏离指数D为0.305 4,杂合子处于过剩状态。从以上数据中可以看出,兰州鲇野生群体遗传变异程度较大,但是有效等位基因数偏低,有必要对兰州鲇野生种质资源及时加以保护。     

企鹅珍珠贝同工酶酶谱特征及其遗传分析

采用垂直板状聚丙烯酰胺梯度凝胶电泳分离技术,对企鹅珍珠贝闭壳肌、外套膜、鳃、消化盲囊、足组织的SOD、EST、LDH、G6PDH、MDH、ME 6种同工酶酶谱特征及其遗传控制进行了研究。6种同工酶在不同组织中的表达有明显的差异,同工酶分析共检测到18个位点,其中有16个位点具多态性,群体中,多态位点比例为88.8％,平均杂合度为0.396±0.029。有13个多态位点上的基因型频率与Hardy-Weinberg定律相符(P>0.05),位点Ldh-1、Ldh-2、Sod-2极显著偏离该平衡(P<0.01)。在G6pdh-1位点发现较高频率的无效等位基因。     

江鳕生化遗传学特性及群体遗传结构初步分析

为了解江鳕(Lota lota)生化遗传特性及其遗传结构,采用聚丙烯酰胺凝胶电泳技术,分析了乳酸脱氢酶(LDH)、乙醇脱氢酶(ADH)、苹果酸脱氢酶(MDH)和异柠檬酸脱氢酶(IDHP)等4种同工酶在额尔齐斯河江鳕肌肉、肝脏、心脏、脾脏、肾脏和眼睛6种组织的组织表达模式。结果表明：额尔齐斯河江鳕的4种同工酶在6种组织中的分布具有明显的组织特异性;其中LDH、MDH、ADH 3种酶共记录出2个基因位点,其中LDH1～LDH5、ADH1～ADH3、MDH1和MDH2为10个多态位点;多态位点的基因频率为0.125～0.875,多态位点比例为83.33%;等位基因数为22个,位点平均有效等位基因数为1.833 3;平均期望杂合度为0.310 9,平均观测杂合度为0.423 4, Hardy-Weinberg遗传偏离指数为0.361 9。杂合子处于过剩状态,表明额尔齐斯河江鳕尚未经历人工定向改良,其群体种质资源库仍有较大的变异程度,可为后续的人工育种提供良好的亲本。此外,肌肉中IDHP可作为江鳕特有的生化遗传学标记,为种质鉴定提供理论依据。[中国渔业质量与标注,2022,12(3):45-50...     

高寒鲤、荷包红鲤、松浦鲤和德国镜鲤同工酶分析

采用聚丙烯酰胺凝胶电泳技术对高寒鲤Cyprinus carpio、荷包红鲤Cyprinus carpio wuyuanensis、松浦鲤Cyprinus carpio Songpu和德国镜鲤眼(E)、心(H)、肾(K)、肝胰脏(L),和肌肉(M)组织中超氧物歧化酶(SOD)、乙醇脱氢酶(ADH)、α-淀粉酶(α-AMY)、过氧化物酶(POD)、苹果酸酶(ME)、葡萄糖-6-磷酸脱氢酶(G-6-PDH)、乳酸脱氢酶(LDH)、酯酶(EST),和山梨醇脱氢酶(SDH)等9种同工酶进行了电泳分析。结果表明:4种鲤同工酶谱具有明显的组织特异性,其中肝胰脏和肾脏表达最为显著。4个鲤群体9种同工酶共记录了17个基因座位,多态座位比例P平均为27.865%,平均预期杂合度He’介于0.1329~0.1451之间。Shannon’s多样性指数显示,4个群体的遗传变异由高到低依次为:荷包红鲤>高寒鲤>松浦鲤>德国镜鲤。4种鲤具有较丰富的遗传多样性,较高的遗传变异水平,对种质资源的研究开发及利用有重要意义。     

红鳍东方纯养殖群体生化遗传变异初步研究

采用水平凝胶电泳技术对红鳍东方纯养殖群体进行了同工酶分析.本实验采用肌肉和肝脏两种组织,分析了8种酶,检测到9个位点,在0.99水平上,PGM*和IDHP*表现为多态,MPI*、LDH*、AAT*、SOD*、MDH-1*、MDH-2*和G3PDH*均为单态,多态位点比例为0.222 2,平均预期杂合度为0.099 8,实际观测杂合度为0.046 7,平均有效等位基因数目为1.184 0,PGM*位点的遗传偏离指数为-0.070 7,杂合子缺失,IDHP*位点无杂合子,遗传偏离指数为-1.     

红鳍东方鲀养殖群体生化遗传变异初步研究

采用水平凝胶电泳技术对红鳍东方鲀养殖群体进行了同工酶分析。本实验采用肌肉和肝脏两种组织,分析了8种酶,检测到9个位点,在0.99水平上,PGM*和IDHP*表现为多态,MPI*、LDH*、AAT*、SOD*、MDH-1*、MDH-2*和G3PDH*均为单态,多态位点比例为0.2222,平均预期杂合度为0.0998,实际观测杂合度为0.0467,平均有效等位基因数目为1.1840,PGM*位点的遗传偏离指数为-0.0707,杂合子缺失,IDHP*位点无杂合子,遗传偏离指数为-1。     

广西野生鲤与建鲤的遗传多样性分析

利用10个微卫星标记,对2代群体选育的建鲤(Cyprinus carpio var.Jian)和封闭水体的广西野生鲤鱼进行遗传多样性分析,共检测到53个等位基因,等位基因位点数在4~7个之间,平均等位基因数5.3个,片段长度在118~284 bp之间,有效等位基因在1.167 5~1.520 3,平均为1.360 2,广西野生鲤群体的有效等位基因数1.562,大于建鲤的1.388;位点观测杂合度在0.397~0.762之间,平均为0.562 6,期望杂合度0.301~0.629之间,平均0.463 3,广西野生鲤群体的期望杂合度0.581,大于建鲤的0.473;微卫星位点多态性信息含量(PIC)在0.289 7~0.685 0之间,平均多态信息含量0.438 8,为中度多态性,广西野生鲤群体多态信息含量0.685,大于建鲤的0.424,两个群体平均基因分化系数为0.106 9,广西本地野生鲤与建鲤的遗传距离为0.1463,相似性系数为0.828 4,表明广西野生鲤与建鲤之间存在明显的遗传异质性。     

西施舌同工酶的组织特异性与多态性初步研究

采用垂直聚丙烯酰胺凝胶电泳技术对西施舌（Coelomactra antiquata）闭壳肌、鳃、外套膜、消化腺和足肌5种组织的18种同工酶进行组织特异性分析,并对其中11种同工酶进行了多态性的筛选。结果表明,西施舌同工酶的表达具有明显的组织特异性。消化腺与肌肉组织中的11种酶（ADH、AK、DIA、EST、GPI、IDH、MDH、PGM、SDH、SOD和XDH）可以得到稳定而清晰的酶谱。在11种酶的17个基因位点中有6个位点（aDH、EST-1、MDH-1、PGM,SOD．J和XDI-1）为多态位点,多态位点比例为35．3％。平均观测杂合度（风）和预期杂合度（见）分别为0．360和0．519,平均等位基因数目（M）为4．40。     

黄、渤海半滑舌鳎种群遗传结构的同工酶分析

采用水平淀粉凝胶电泳技术检测黄海、渤海半滑舌鳎两个群体的同工酶组织特异性并分析和研究其群体遗传结构。结果表明,半滑舌鳎的眼、鳃、肌肉、心脏、肝脏、肾脏、脾脏、鳍条、脑等9种组织和器官对18种同工酶的表达呈现明显的组织特异性。对肌肉和肝脏两种组织的PGDH、MPI、IDHP、SOD、AAT、MDH、LDH、G3PDH、PGM、LAP、ADH、SDH和ALP共13种同工酶进行了遗传学分析,共记录16个基因座位。其中,黄海群体在4个基因位点(IDHP、PGM、G3PDH、SDH)、渤海群体在5个基因位点(IDHP、PGM、MDH2、SDH、ALP)表现为多态,黄海和渤海群体的多态位点比例分别为0.2500和0.3125;两个群体的平均观测杂合度分别为0.0143、0.0104,平均预期杂合度分别为0.0140、0.0102;平均有效等位基因数则分别为1.0151和1.0108。两群体间的遗传距离为0.00012。半滑舌鳎的两个群体遗传多样性水平较低,两群体间无明显的遗传分化。     

日本蟳同工酶组织特异性及生化遗传分析

以日本虫寻为研究材料,采用聚丙烯酰胺凝胶垂直平板电泳方法,分析了肌肉、眼球、鳃、心脏和肝胰腺5种器官或组织中LDH、ADH、MDH、ACP、AKP、GDH、R-AMY、α-AMY、MEP、EST和SOD共11种同工酶的表达情况。日本虫寻体内同工酶的表达具有明显的组织特异性。在实验中共检测了38个位点,其中Adh、Est-3、M ep-5、α-Amy-1、sMdh-3和Akp-4共6个多态位点,多态位点比例为15.79%,平均杂合度为0.09。     

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).     

Evaluation of a Fast Method Based on the Presence of Two Restriction Sites in the Mitochondrial ND5 (mt ND5) Gene for the Identification of Scomber Species

The purpose of this work was to evaluate the suitability of a method based on the presence of two restriction sites (for Hae III and Hindf I) in the mitochondrial NADH dehydrogenase subunit 5 (mt ND5) gene to identify Scomber species. The evaluation was performed on 144 reference and market samples by sequencing of the entire 505-bp fragment of the mt ND5 gene and of a 464-bp fragment of the Kocher fragment of the cytochrome b gene (mt Cytb). Sequence analysis of any of the two fragments allows the identification of each of the four Scomber species, but S. japonicus and S. colias had the same restriction sites at the ND5 amplicon and would not have been differentiated by this analysis. Similarly, loss of the Hae III site in some S. scombrus individuals would have misidentified them as not being Scomber. All the market products were correctly labeled except one acquired in Spain labeled as originating in the Atlantic and containing S. japonicus.     

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.