俄罗斯鲟的细胞遗传学分析

采用体内注射PHA和秋水仙素,肾细胞短期培养,常规空气干燥法制备俄罗斯鲟(Acipenser gueldenstaedtiBrandt)的染色体,对其肾细胞染色体数目统计分析表明,俄罗斯鲟染色体组由236±2条染色体组成,其中具有明显着丝点的染色体为120条,其余为小染色体(点状染色体);核型公式为80m 16sm 24st,t 116mc,NF=332;采用德国PartecpasⅢ型流式细胞分析仪,以鸡红细胞为标准DNA(含量为2.3pg.N-1),测定俄罗斯鲟体细胞DNA含量为12.24pg.N-1,与染色体分析结果比较倍性一致。综合以上两项结果可得出,俄罗斯鲟为八倍体鱼。     

白乌鳢染色体核型和DNA含量分析

通过向活体白乌鳢(Opniocepnalus argus)腹腔注射植物血凝素(PHA)和秋水仙素进行短期药物处理后,制备染色体标本并对其核型进行分析。以鸡血细胞DNA含量为标准(2.50 pg),用流式细胞仪测定了白乌鳢外周血细胞的DNA含量。结果表明:(1)白乌鳢的染色体组为2 n=48,核型公式为4 m+22 st+22 t,总臂数NF=52,无性染色体。(2)白乌鳢的DNA含量为鸡血对照的0.59倍,其DNA含量为(1.48±0.04)pg/N。白乌鳢的染色体数和DNA含量均显示其具有二倍体特征。依据实验结果推论白乌鳢为乌鳢的白化变异个体。     

中国胭脂鱼的细胞遗传学分析

采用植物血凝素、秋水仙素活体注射和肾细胞直接制片法分析了中国胭脂鱼(Myxiocyprinus asiaticus)的染色体核型和Ag-NORs显带;并以中国胭脂鱼血细胞为样本,鸡血细胞DNA含量为标准(2.50 pg),用流式细胞仪测定了中国胭脂鱼的 DNA 含量.结果表明:(1)中国胭脂鱼染色体数目2n=100,核型公式为10 m+4 sm+12 st+74 t, NF=114,未观察到次缢痕及随体,亦未发现有性染色体.(2)中国胭脂鱼染色体具有1对Ag-NORs,位于第1对染色体短臂上,间期核中Ag-NORs的数目为1~2个,未见Ag-NORs的联合现象.(3)PI和DAPI作为荧光染料,得出中国胭脂鱼DNA含量分别为5.50±0.24 pg和6.16±0.03 pg.(4)中国胭脂鱼为四倍体,在特定的分类阶元中属于较原始的鱼类.     

太湖似刺鳊(鱼句)染色体组型分析及细胞核DNA含量

采用PHA、秋水仙素碱腹腔或背部肌肉注射,活体培养法,用空气干燥法制片,运用Micromeasure version 3.3染色体分析软件和Photoshop 7.0对似刺鳊(鱼句)染色体数目和核型进行了分析;同时,取似刺鳊鱼句血细胞、尾鳍、鳃、肌肉、性腺和肝脏为材料,以鸡血细胞为DNA标准(2.50 pg/2c),使用EPICS-XL型流式细胞仪测定了似刺鳊(鱼句)细胞核DNA含量.结果显示:染色体众数2n=50,染色体大小的绝对值为0.86～2.32 μm,平均长度为1.63 μm,未观察到次缢痕及异配型染色体,亦未发现有随体,核型公式为18m+20sm+8st+4t,NF=88.6个组织细胞核DNA含量分别为:尾鳍3.779 pg/2c,鳃4.007 pg/2c,肌肉3.819 pg/2c,性腺(卵巢4.242 pg/2c、精巢1.842 pg/2c),肝脏3.905 pg/2c.尾鳍、鳃、肌肉和肝脏的细胞核DNA含量不存在显著差异(P＞0.05),但都极显著高于血细胞DNA含量(P<0.01);卵巢细胞核DNA含量约为精巢的2倍.     

团头鲂核型与DNA含量分析研究

采用PHA体内培养法，取鱼体肾细胞用空气干燥法制备团头鲂染色体标本。经核型分析，团头鲂的核型为2n=48,26m 18sm 4st，臂数（NF）为92。用流式细胞仪测量外周血红血球细胞核的DNA含量为2．66pg/N。实验结果分析表明团头舫染色体数及DNA含量是稳定的，其核型公式与有关文献的报道略有差异。     

太湖似刺鳊鮈染色体组型分析及细胞核DNA含量

采用PHA、秋水仙素碱腹腔或背部肌肉注射，活体培养法，用空气干燥法制片，运用Micromeasure version 3.3染色体分析软件和Photoshop 7.0对似刺鳊鮈染色体数目和核型进行了分析；同时，取似刺鳊鮈血细胞、尾鳍、鳃、肌肉、性腺和肝脏为材料，以鸡血细胞为DNA标准（2.50pg/2c），使用EPICS-XL型流式细胞仪测定了似刺鳊鮈细胞核DNA含量。结果显示：染色体众数2n=50，染色体大小的绝对值为0.86～2.32µm，平均长度为1.63µm，未观察到次缢痕及异配型染色体，亦未发现有随体，核型公式为18m+20sm+8st+4t，NF=88。6个组织细胞核DNA含量分别为：尾鳍3.779 pg/2c，鳃4.007 pg/2c，肌肉3.819 pg/2c，性腺(卵巢4.242 pg/2c、精巢1.842 pg/2c)，肝脏3.905 pg/2c。尾鳍、鳃、肌肉和肝脏的细胞核DNA含量不存在显著差异（p＞0.05），但都极显著高于血细胞DNA含量（p＜0.01）；卵巢细胞核DNA含量约为精巢的2倍。     

小体鲟血清卵黄蛋白原和 Ca2+浓度与卵巢发育的关系

采用ELISA方法、分光光度计法和组织学方法,系统研究了不同年龄小体鲟(Acipenser ruthenus)血清卵黄蛋白原(Vitellogenin Vg)、血清钙离子(Galcium Ca2+)含量与卵巢发育变化的关系.结果表明:血清Vg浓度、Ca2+浓度与卵巢的发育时期相关;在卵黄沉积期内,血清中Vg浓度与Ca2+浓度呈线性正相关(R2=0.926 4);卵黄生成前期和沉积初期,血清中Vg浓度和Ca2+含量较低;卵黄沉积期内,卵母细胞由沉积初期的0.56 mm 增大到卵黄沉积末期的2.0l mm,血清Vg质量浓度由110.65 μg/mL 上升到242.22 μg/mL,血清Ca2+浓度由2.34 mol/L增大到2.72 mol/L.对同年龄的雌、雄小体鲟血清Vg浓度和Ca2+浓度测定表明,根据血清中Vg和Ca2+含量差别,可以区分出沉积期小体鲟的性别.     

5种鲟、鳇鱼基因组DNA遗传多样性分析

以史氏鲟(Acipenserschrencki)、达氏鳇(Husodauricus)俄罗斯鲟(A.gueldenstaedti)、小体鲟(A.ruthenus)西伯利亚鲟(A.baeri)的基因组DNA为实验材料,用改进的DNA提取方法获得了完整的基因组DNA片段。通过25个SSLP及Ⅰ型引物对5种鲟鳇鱼的基因组DNA进行PCR多态性引物筛选,获得11个能扩增出遗传多态性的有效引物,通过对5种鱼的PCR分析,平均遗传距离为0.748,遗传距离最大的为达氏鳇和小体鲟之间为0.9355,DNA分析结果还显示,鲟鳇鱼的遗传多样性程度十分低下(47.93%)。同时建立了5种鲟鳇鱼的聚类图。     

洞庭青鲫的染色体核型分析及品种鉴定

对洞庭青鲫(Carassius auratusvar.Dongtingking)肾细胞染色体的核型进行了分析,并对此鱼种进行了品种鉴定。核型分析表明,洞庭青鲫的肾细胞染色体组是由100条染色体组成,染色体组型按着丝粒位置可分为四组,分别是中部着丝粒染色体、亚中部着丝粒染色体、亚端部着丝粒染色体、端部着丝粒染色体。其中中部着丝粒染色体15对,亚中部着丝粒染色体10对,亚端部着丝粒染色体13对,端部着丝粒染色体12对,每对染色体均由二条同源染色体组成。洞庭青鲫肌肉细胞的DNA相对含量(55.75±1.59)(17尾)与二倍体红鲫(Carassiusauratusvar.Red)肌肉细胞DNA相对含量(55.68±1.64)(15尾)基本相等。结果说明,洞庭青鲫是一种二倍体鲫鱼,其染色体数目为2n=100,核型公式为2n=30m+20sm+26st+24t,NF=150。     

中国6种经济鱼类的基因组大小测定

采用流式细胞术,以人(Homo sapiens)淋巴细胞DNA含量(7.00pg/2C)为标准,以鱼的红血细胞为材料,测定中国6种重要经济鱼类条纹斑竹鲨(Chiloscyllium plagiosum)、斜带石斑鱼(Epinephelus coioides)、赤点石斑鱼(Epinephelus akaara)、大黄鱼(Pseudosciaena crocea)、中华乌塘鳢(Bostrichthys sinensis)、大菱鲆(Scophthalmus maximus)的基因组大小(C-值)。结果显示,这6种经济鱼类的单倍体DNA含量分别为:条纹斑竹鲨(4.91±0.24)pg;斜带石斑鱼(1.25±0.04)pg;赤点石斑鱼(1.23±0.11)pg;大黄鱼(0.76±0.03)pg;中华乌塘鳢(0.85±0.04)pg;大菱鲆(0.65±0.01)pg。研究结果可为这6种经济鱼类的种质鉴定提供依据。此外,根据本研究的实验结果并结合其他鱼类的基因组大小资料,对鱼类基因组大小与其染色体数目及进化地位之间的相关性进行了探讨,对比分析显示,鱼类进化地位越高则DNA含量越少,同时鱼类基因组的大小差异存在复杂性,并不完全与染色体数目相关。本研究还就鱼类基因组大小的测定方法等问题提出建议,认为应采用流式细胞术和人淋巴细胞作为规范的检测方法和对照标准。     

Protein and amino acid composition from the mantle of juvenile O ctopus vulgaris exposed to prolonged starvation

Protein and amino acid composition of the mantle of juvenile O ctopus vulgaris (Cuvier, 1797) during fasting for 27 days were determined. Average protein content of octopus mantle was of 711.19 ± 46.80 g kg^?1 DW, and it decreased with increasing fasting days. The non‐essential amino acids content was higher (486.18 ± 11.08 g kg^?1 protein) than essential amino acids (425.82 ± 9.15 g kg^?1 protein) at the start of the experiment (unstarved animals). The results suggest that the amino acid profile of the mantle where the most abundant amino acids are Arg, His, Lys, Gly, Leu and Pro could indicate a prolonged fasting condition (>20 days) or poor nutrition of O . vulgaris. This study supports the idea of using mantle for metabolic needs of starved O . vulgaris suggesting that the degradation pathway of amino acids to pyruvate and tricarboxylic acid cycle intermediates was favoured contrary to the degradation pathway of ketogenic amino acids. Special considerations should be taken concerning Thr, Ile, Ser, Ala, Asx (Asp, Asn), Glx (Glu, Gln) (because of their fast intake) and Lys and His (due to their stable contents) during a prolonged period of fasting.     

美人鱼发光杆菌对凡纳滨对虾非特异性 免疫功能及抗病力的影响

在基础饲料中分别添加0.1%和1%美人鱼发光杆菌灭活菌、0.1%美人鱼发光杆菌活菌配制成3种免疫实验饲料,以基础饲料为空白对照组饲料,每组设3个平行样。对个体质量为(4.83±0.36)g的凡纳滨对虾进行为期20 d的饲养实验,分别在0、5、10、15和20d进行取样,以血清中的酚氧化酶(PO)、酸性磷酸酶(ACP)、碱性磷酸酶(AKP)、超氧化物歧化酶(SOD)和溶菌酶(UL)活性为免疫指标,探讨了美人鱼发光杆菌作为免疫制剂对凡纳滨对虾非特异性免疫效应的影响;在投喂免疫饲料后的第22天,按0.004 2 kg/kg体重的剂量,直接投喂对虾白斑综合征病毒(WSSV)病料,并记录累积死亡率。结果表明,美人鱼发光杆菌免疫实验组对凡纳滨对虾血清中PO、ACP、AKP、UL和SOD活性影响明显高于对照组,并且在饲料中添加美人鱼发光杆菌后,明显提高了对虾抵御WSSV感染的能力。其中0.1%美人鱼发光杆菌活菌实验组的抗病毒感染能力最强,WSSV感染14d内累计死亡率为63.3%±5.8%;而对照组为96.7%±3.3%。研究表明,美人鱼发光杆菌添加在对虾饲料中能提高凡纳滨对虾非特异性免疫水平,增强抵抗疾病的能力,将其作为对虾免疫增强剂具有良好的应用前景。     

Effects of Spirulina platensis as a feed additive on growth and coloration of blue dolphin cichlids (Cyrtocara moorii Boulunger, 1902)

This study was carried out to investigate the effects of replacing fish meal with dietary Spirulina as a feed supplement on the growth performance and coloration of blue dolphin cichlids (Cyrtocara moorii). Five isonitrogenous (47% crude protein) and isocaloric (17.36 kJ/g digestible energy) diets were for formulated to replace FM with 0, 5, 10, 15 and 20% Spirulina (designated as Control, SP5, SP10, SP15 and SP20 respectively) and fed to the fish (initial body weight, 3.15 ± 0.01 g). Fish were randomly distributed into fifteen 120 L aquariums (26.5 ± 1.00°C), 15 fish per aquarium. The diets were tested in triplicate for 12 weeks. Experimental groups were fed twice daily (09:00 and 17:00) by hand to satiation. At the end of the feeding trial, significantly (p < 0.05) higher weight gain (WG), specific growth rate (SGR), protein efficiency ratio (PER) and lower feed conversion ratio (FCR) were observed in fish fed the SP10 diet when compared to the SP20 diet. There was no significant difference in these parameters between the other groups. The skin coloration of blue dolphin cichlid fed a diet containing Spirulina meal was enhanced. The best coloration was observed in the SP15 group. These impressions were objectively validated by chemical determinations of carotenoids extracted from fish skins and passed statistical tests of significance. The study findings show that Spirulina meal does not diminish growth rates except at very high levels.     

Sea bream culture in Egypt; status, constraints and potential

Marine fish farming in Egypt began in 1976 with the culture of gilthead sea bream, (Sparus aurata) as this fish was notably adaptable to brackish and marine pond conditions. Today, marine fish and shrimp farms amount to about 19,000 ha, out of which 42% is already in production while the rest, i.e., 58% is still under construction. In 1997, cultured gilthead sea bream production of 2,250 tons made up 3% of the 75,000 tons total aquaculture catch. In polyculture, usually with the grey mullet and sea bass, gilthead sea bream contributed 440 kg ha^–1 to the total yield of 1,700 kg ha^–1 (26%) over a period of 16 months. For the same period, the yield of monoculture ponds averaged 100 kg ha^–1, while in marine cages, yields ranged from 4–10 kg m³. In 1996–1997, fry of 0.25–1 g and fingerlings 1–10 g with a total of 3 million, were collected from the wild and 1 million fry were produced in the three marine hatcheries out of the four existing ones. The development of sea bream culture in Egypt is now severely inhibited by the shortage of seeds and adequate feeds. Exports of both sea bream and sea bass, during 1994–1996 averaged 1,300 tons per year.     

Dietary thiamin and pyridoxine requirements of fingerling Indian major carp,Cirrhinus mrigala (Hamilton)

Two experiments were conducted to quantify the dietary thiamin (experiment I) and pyridoxine (experiment II) requirements of fingerling Cirrhinus mrigala for 16 weeks. In experiment I, dietary thiamin requirement was determined by feeding seven casein–gelatin‐based diets (400 g kg^?1 CP; 18.69 kJ g^?1 GE) with graded levels of thiamin (0, 0.5, 1, 2, 4, 8 and 16 mg kg^?1 diet) to triplicate groups of fish (6.15 ± 0.37 cm; 1.89 ± 0.12 g). Fish fed diet with 2 mg kg^?1 thiamin had highest specific growth rate (SGR), protein retention (PR), RNA/DNA ratio, haemoglobin (Hb), haematocrit (Hct), RBCs and best feed conversion ratio (FCR). However, highest liver thiamin concentration was recorded in fish fed 4 mg thiamin kg^?1 diet. Broken‐line analysis of SGR, PR and liver thiamin concentrations exhibited the thiamin requirement in the range of 1.79–3.34 mg kg^?1 diet (0.096–0.179 μg thiamin kJ^?1 gross energy). In experiment II, six casein–gelatin‐based diets (400 g kg^?1 CP; 18.69 kJ g^?1 GE) containing graded levels of pyridoxine (0, 2, 4, 6, 8 and 10 mg kg^?1 diet) were fed to triplicate groups of fish (6.35 ± 0.37 cm; 1.97 ± 0.12 g). Fish fed diet containing 6 mg kg^?1 pyridoxine showed best SGR, FCR, PR, RNA/DNA ratio, Hb, Hct and RBCs, whereas maximum liver pyridoxine concentration was recorded in fish fed 8 mg kg^?1 dietary pyridoxine. Broken‐line analysis of SGR, PR and liver pyridoxine concentrations reflected the pyridoxine requirement from 5.63 to 8.61 mg kg^?1 diet. Data generated during this study would be useful in formulating thiamin‐ and pyridoxine‐balanced feeds for the intensive culture of this fish.     

A Minchinia mercenariae‐like parasite infects cockles Cerastoderma edule in Galicia (NW Spain)

The cockle Cerastoderma edule fishery has traditionally been the most important shellfish species in terms of biomass in Galicia (NW Spain). In the course of a survey of the histopathological conditions affecting this species in the Ria of Arousa, a haplosporidan parasite that had not been observed in Galicia was detected in one of the most productive cockle beds of Galicia. Uni‐ and binucleate cells and multinucleate plasmodia were observed in the connective tissue mainly in the digestive area, gills and gonad. The parasite showed low prevalence, and it was not associated with abnormal cockle mortality. Molecular identification showed that this parasite was closely related to the haplosporidan Minchinia mercenariae that had been reported infecting hard clams Mercenaria mercenaria from the Atlantic coast of the United States. The molecular characterization of its SSU rDNA region allowed obtaining a fragment of 1,796 bp showing 98% homology with M. mercenariae parasite. Phylogenetic analysis supported this identification as this parasite was clustered in the same clade as M. mercenariae from the United States and other M. mercenariae‐like sequences from the UK, with bootstrap value of 99%. The occurrence of M. mercenariae‐like parasites infecting molluscs outside the United States is confirmed.     

A novel approach to denitrification processes in a zero-discharge recirculating system for small-scale urban aquaculture

This paper presents an innovative process to solve the nitrate build-up problem in recirculating aquaculture systems (RAS). The novel aspects of the process lie in a denitrification bioreactor system that uses solid cotton wool as the primary carbon source and a unique degassing chamber. In the latter, the water is physically stripped of dissolved gaseous O₂ (by means of a Venturi vacuum tube), and the subsequent denitrification becomes more efficient due to elimination of the problems of oxygen inhibition of denitrification and aerobic consumption of cotton wool. The cotton wool medium also serves as a physical barrier that traps organic particles, which, in turn, act as an additional carbon source for denitrification. Operation in the proposed system gives an extremely low C/N ratio of 0.82 g of cotton wool/g of nitrate N, which contributes to a significant reduction of biofilter volume. The additional advantage of using solid cotton wool as the carbon source is that it does not release organic residuals into the liquid to be recycled. Operation of the system over a long period consistently produced effluents with low nitrate levels (below 10 mg N/l), and there was only a very small need to replace system water. The overall treatment scheme, also incorporating an aerobic nitrification biofilter and a granular filtration device, produced water of excellent quality, i.e., with near-zero levels of nitrite and ammonia, a sufficiently high pH for aquaculture, and low turbidity. The proposed system thus provides a solution for sustainable small-scale, urban aquaculture operation with a very high recovery of water (over 99%) and minimal waste disposal.     

Fertilization by refrigerator stored sperm of the Indian major carp, Labeo calbasu (Hamilton, 1822)

This study reports on the spermatological properties, and on the development of a protocol for refrigerator storage (4°C) of Labeo calbasu (Hamilton, 1822) sperm for artificial breeding. Volume, motility, concentration and pH of the freshly collected sperm were 2.21 ± 0.53 (μL g^?1 of fish weight) (mean ± SD), 95 ± 1 (%), 1.93 ± 0.44 × 10⁹ (cells mL^?1) and 7.56 ± 0.17 respectively. Sperm activation was evaluated at different osmolalities of NaCl solution, and motility ceased completely when osmolality of the extender was ≥287 mOsmol kg^?1. Sperm retained motility for 24, 72 and 108 h, after refrigerator storage when sperm were undiluted, suspended in Alsever's solution and suspended in Alsever's solution containing 5% methanol respectively. Fertilization rate of fresh eggs with sperm stored at 4°C in Alsever's solution and Alsever's solution containing 5% methanol was 77% and 60% with a hatching rate of 60% and 43% respectively. The fertilization and hatching success of the stored sperm suggests potential to use refrigeration for transporting genetic material to hatcheries for artificial breeding of L. calbasu in Bangladesh.     

Effects of metomidate anaesthesia or transfer to pur sea water on plasma parameters in ammonia-exposed Atlantic salmon (Salmo salar L) in sea water

Atlantic salmon (Salmo salar L) postsmolts weighing 150 ± 53 g were exposed to 14–15 mg l^–1 TA-N (total ammonia-N) in sea water in 1 m³ tanks for 24h. Blood samples were then taken A) immediately after the fish were netted from the exposure tanks and stunned by a blow to the head; B) 2–20 min after the fish were transferred to 15 l of an anaesthetic solution of metomidate in ammonia-free sea water; or C) 2–20 min after the fish were transferred to 15 l of ammonia-free sea water. Plasma TA-N level was 18% lower in the anaesthetised fish compared to in the fish sampled directly from the exposure tanks (p 0.05), and accordingly 16% lower in the fish transferred to pure sea water although this difference was not significant (p = 0.07). Plasma glucose level was higher in the fish transferred to pure sea water than in the fish receiving the two other treatments (p 0.05), but plasma urea, osmolality, Na^{+, Cl–, Ca2+ or Mg2+} levels did not vary significantly between the different treatments. Plasma TA-N level increased with time in the fish in the metomidate solution (p 0.02).