Growth and salinity tolerance in hybrids within Salmo sp. and Salvelinus sp.

Attempts were made to complete all possible interspecific hybrid crosses between Atlantic salmon (Salmo salar), rainbow trout (Salmo gairdneri), brook trout (Salvelinus fontinalis), lake trout (Salvelinus namaycush), and Arctic char (Salvelinus alpinus). Survival was appreciable only in (giving female first) lake × brook, salmon × char, brook × char and char × brook hybrids. Growth rates over a weight increment of 3–30 g averaged 2.14% wet weight/day for all species and hybrids (14.5–17.0°C — excess rations). The highest growth rate, 2.74%, was obtained with the brook (female) × char (male) hybrid and the lowest, 1.63%, in lake trout. Salmon (female) × char (male) hybrids grew faster than salmon; brook trout (female) × char (male) hybrids grew faster than brook trout. Salmo species grew no faster than Salvelinus species but became silvery and had greater salinity tolerance at a smaller size and earlier age. Intergeneric hybrids between female Salmo spp. and male Salvelinus spp. more closely resembled the female parent in processes related to smoltification (silvering and salinity tolerance).     

海洋尖尾藻对2种海洋微藻的摄食特征研究

为研究海洋尖尾藻对双色藻和齿状纹石藻的摄食特征,分别采用2种海洋微藻为饵料培养海洋尖尾藻,分析海洋尖尾藻对2种海洋微藻的摄食过程、培养液颜色变化特征和摄食规律。结果显示,海洋尖尾藻摄食双色藻时将藻丝一段一段慢慢裹入纵沟,而齿状纹石藻整个细胞同时被裹入纵沟。海洋尖尾藻接种6 h后,对2种海洋微藻的摄食率均为100%。随着海洋尖尾藻细胞初始密度(双色藻培养液中分别为0.8×104、2.4×103和0.8×103个/mL,齿状纹石藻培养液中分别为3.9×103、2.4×103和1.7×103个/mL)降低,其种群在初始密度为3.4×107个/mL的双色藻培养液中达到稳定期所需时间增加,分别为接种后第3、4和6天,双色藻被摄食完毕所需时间也增加,分别为接种后第5、10和15天;海洋尖尾藻种群在初始密度为6.6×105个/mL的齿状纹石藻培养液中达到稳定期所需时间增加,分别为接种后第4、5和12天,齿状纹石藻被摄食完毕所需时间也增加,分别为接种后第6、7和13天。研究表明,海洋尖尾藻对不同大小和体制类型的双色藻和齿状纹石藻的摄食过程不同,培养方式对培养液颜色变化产生影响,饵料藻种类以及饵料藻和海洋尖尾藻最初浓度配比会影响海洋尖尾藻摄食,15 d培养过程中双色藻种群和齿状纹石藻种群均向海洋尖尾藻种群发生了演替。     

Sterol requirement of juvenile lobsters, Homarus sp.

Juvenile lobsters were fed purified or unrefined diets in which the qualitative and quantitative sterol composition varied. Dietary cholesterol was required. A level of dietary cholesterol as low as 0.12% (dry weight) in a purified diet was satisfactory for normal growth and survival. No significant increases in growth were observed when lobsters were fed unrefined diets with cholesterol levels ranging from 0.19 to 0.59% (dry weight). Total cholesterol content of the whole body tissue lipid ranged from 0.012 to 0.046% (wet weight), lowest values being characteristically associated with those animals fed purified diets virtually devoid of cholesterol. Serum sterol levels were similar except for reduced levels associated with the sterol-free diet.Total replacement of cholesterol with a mixture of phytosterols composed primarily of β-sitosterol did not yield good growth and survival. Phytosterols composed large proportions of the total body sterols of those lobsters fed diets containing phytosterols exclusively. At least a portion and possibly all of the sterol requirement of juvenile lobsters is specific for cholesterol.     

Fusarium sp. infections in the freshwater prawn Macrobrachium rosenbergii (De Man)

A fungus of the genus Fusarium was associated with black spot cuticular lesions on Macrobrachium rosenbergii (De Man) and appeared opportunistic rather than invasive. Attempts to transmit the fungus to non-affected prawns were negative. Comparisons are made with other Fusarium sp. isolated from crustaceans.     

根瘤菌N_1对扁藻生长影响的研究

研究了由海藻培养体系中分离获得的10株细菌对扁藻生长影响。试验结果表明,菌株N1对自然带菌扁藻及除菌扁藻的生长均有明显的促进作用;经16SrDNA分析表明,菌株N1为根瘤菌属细菌。     

臭氧处理海水对小球藻的生理效应

采用经臭氧处理的海水培养小球藻，分析了小球藻的相对增长速率、叶绿素-a含量，DNA和RNA含量及海水中三氮含量的变化，结果表明：1、一定剂量的臭氧处理可提高小球藻的生长速度和叶绿素的含量，高剂量的处理会抑制小球藻的生长。2、藻细胞中DNA含量对臭氧处理表现的相对稳定，而RNA含量比较敏感，一定剂量的臭氧处理可引起RNA含量增加。3、经臭氧处理的海水，硝态氮（NO3^--N)的含量有所提高，而铵态氮（NH4^ -N)和亚硝态氮（NO2^--N)的含量降低。     

N/P对菱形藻生长速率和营养成分含量的影响

研究了N/P(1∶1、5∶1、12.5∶1、30∶1、50∶1、80∶1)对菱形藻的生长速率、营养成分含量及氮磷利用率的影响。试验结果表明,(1)N/P对菱形藻的生长影响显著(P0.05),其中N/P为12.5∶1时,比生长速率最大,当N/P5∶1和N/P50∶1时,菱形藻的生长较慢,比生长速率为0.3～0.6/d;(2)藻细胞营养成分的含量也受N/P的影响:在N/P为12.5∶1时,叶绿素的含量达到1.81g/ml,总脂肪、蛋白质、胞外多糖和胞内多糖的含量分别占干质量的29.9%、17.8%、15.3%、14.2%,高于其他N/P下的营养成分含量;(3)培养后水体中氮磷的含量明显下降,TN的利用率之间有显著性差异(P0.05),利用率均超过55%,最高为30∶1,达78%,TP的利用率之间无显著性差异(P0.05),均高于90%。     

Growth of three salmonid species in mono and double culture (Salmo salar L., S. trutta L. and S. gairdneri Rich.)

Juvenile Atlantic salmon, sea trout and rainbow trout were used in an experiment in which two species in each tank were compared with controls of each species separately. Specific growth rate was best in the experimental groups where the two species were reared together. The theory was developed that social facilitation or moderate interaction could cause the better growht. No starvation as a result of competition was discovered in any group.     

Pathogenicity of a non-haemolytic Group B Streptococcus sp. in gulf killifish (Fundulus grandis Baird and Girard)

Gulf killifish (Fundulus grandis) were injected intraperitoneally with different bacterial concentrations and the LD₅₀ were 1.4 × 10⁴ at 96 h and 7.5 × 10 at 168 h. No deaths occurred among fish dipped in the bacterial suspension for different time periods or when the fish were exposed to a 50 parts per thousand hyperosmotic solution prior to dip. Fish became infected when they were injured prior to dipping in the bacterial suspension, but crowding and low oxygen concentration did not precipitate infection. No deaths occurred with oral administration of the bacteria. Bacterial count per gram of tissue was determined for both liver and spleen of infected fish at four, 24-h intervals. There was a significant difference (P > 0.12) between the bacterial counts at the different time periods.     

Growth rates,phycocolloid yield and quality of the red seaweeds, Gracilaria sp., Pterocladia capillacea,Hypnea musciformis, and Hypnea cornuta, in field studies in Israel

The agarophytes Gracilaria sp. and Pterocladia capillacea, and the carrageenophytes Hypnea musciformis and H. cornuta were cultured under field conditions. Specific growth rates appeared to be related to temperature and light intensity. Attached seaweeds had higher annual yields per m² than free-floating samples. The specific growth rate of all four seaweeds was positively related to phycocolloid content in the main growing season. In agar extracts high gel strength coincided with high 3,6 anhydrogalactose content, with high gelling and melting temperature, and with low sulfate content. In the carrageenan extracts low gel strength coincided with low 3,6 anhydrogalactose content, with low gelling and melting temperatures and with high sulfate content. Chemical composition and physical properties of cultured and natural seaweeds were almost the same.     

Slr0351的表达及其在Synechocystis sp. PCC 6803中功能的初步研究

Slr0351是Synechocystis sp.PCC 6803中的未知功能蛋白,其同源蛋白广泛存在于各种蓝藻和铁硫杆菌中.为了确定S1r0351的性质,构建了表达质粒pET-slr0351,并在E.coli中表达Slr0351.在无氧条件下采用亲和层析纯化方法获得了Slr0351,无氧条件下Slr0351呈棕红色,在460 nm处有[2Fe-2S]铁硫簇的特征吸收峰,棕红色Slr0351对氧气敏感,能被连二亚硫酸钠还原,由此表明Slr0351为铁硫蛋白.为了获知slr0351的功能,基于基因同源重组交换的原理,利用Kana抗性片段替换slr0351,将Synechocystis sp.PCC 6803中的slr0351基因缺失,构建了△slr0351突变体.利用紫外-可见吸收光谱仪扫描了△slr0351与野生型Synechocystis sp.PCC 6803 (WT)的吸收光谱,发现正常光照条件下△slr0351的叶绿素a仅为WT的68.8％,slr0351的缺失使蓝藻中叶绿素a含量降低.比较了藻细胞在缺乏不同营养元素和不同光照条件下的生长速率差异,与WT相比,△slr0351具有如下特征:(1)对缺Fe和缺S胁迫条件更敏感;(2)在弱光照条件下△slr0351的光能利用效率和生长速率更低,该现象与△slr351中叶绿素a含量的降低有关.     

Pigmentation of cultured red sea bream, Chrysophrys major, using astaxanthin from Antarctic krill, Euphausia superba, and a mysid, Neomysis sp.

Pigmentation enhancement in cultured red sea bream, Chrysophrys major, was investigated using Antarctic krill, Euphausia superba, and a mysid, Neomysis sp., as a source of astaxanthin. Diets fortified with processed Antarctic krill (krill meal) and its acetone extract, containing 0.82–4.92 mg carotenoids/100 g dry weight, and raw krill and raw mysid supplemented diets, containing about 2.00 mg carotenoids/100 g wet weight, were formulated and tested for carotenoid deposition. The rate of carotenoid deposition in fish fed with raw krill and raw mysid was significantly higher and resulted in distinct pigmentation. The groups fed with the krill meal and acetone extract diets showed varied concentrations of skin carotenoids and resulted in faint pigmentation. Pigmented fish then fed on a carotenoid-free diet for the same length of time showed no apparent differences in the skin pigmentation although the detectable amounts of carotenoids varied. The bream converted some of the dietary astaxanthin to skin tunaxanthin.     

温度和光照对塔胞藻生长的影响

采用梯度法比较了温度、光照度、光照周期对一次性培养的塔胞藻生长的影响。结果表明:塔胞藻对温度的适应范围较广,10~30℃时塔胞藻均可生长,24~28℃为塔胞藻生长的最适温度;光照度4000~10 000 lx时,塔胞藻生物量随光照度的增加而增大,并在10 000 lx时达到最大;塔胞藻在光照周期为16L∶8D时生长最快。     

Growth performance of the rotifers Brachionus plicatilis, B. ‘Nevada’ and B. ‘Cayman’ under different food concentrations

Numerical response experiments were conducted using three strains of the Brachionus plicatilis species complex. They are commonly used in aquaculture, and could also coexist in nature although this has not been studied yet. Brachionus plicatilis sensu stricto (s.s.), B. ‘Cayman’ and B. ‘Nevada’ were cultured at different concentrations of Nannochloropsis oculata (0-40 mg C l^− 1). Growth rate, egg female ratio (EF), fecundity and percentage of ovigerous females were determined at each food concentration. From the growth rate and EF, the egg development time and mortality rate were estimated using the Paloheimo equation. Monod curves with a threshold for zero growth described the relationship between growth rate and food concentration. The three strains had different growth rates at low (< 0.04 mg C l^− 1) and high (> 5.0 mg C l^− 1) food concentrations, but were similar at intermediate food levels. B. ‘Cayman’ had the highest maximum growth rate (1.57 ± 0.07 d^− 1), whereas B. plicatilis s.s. had the less negative minimum growth rate and the highest maximum EF (0.96 ± 0.02 eggs ind^− 1). These differences were attributed to the lowest egg development time of B. ‘Cayman’ (5.95 ± 0.24 h) and the higher starvation resistance of B. plicatilis s.s. (84 ± 12 h), respectively. B. ‘Nevada’ was the inferior competitor at high and low food concentrations due to the higher investment in body growth rather than reproduction. The outcome of competition in hatcheries is predicted to favor B. ‘Cayman’ under high food concentrations, whereas the three species may coexist under moderate food limitation.     

Growth of Tilapia nilotica in ponds with differing histories of organic fertilization

A series of six 0.04 ha ponds that had received varying rates of organic fertilization during 1976 and 1977 were each stocked with 200 Tilapia nilotica for a 3.5 month period during the 1978 growing season. Slotted feeding floors were placed over five of the six ponds and two growing-finishing hogs were placed on each feeding floor. The sixth pond received neither manure nor supplemental feed. Growth of T. nilotica was most rapid in ponds that had a history of relatively high manuring rates. Condition factors paralleled fish growth. Survival was 75% or more in each of the ponds with no apparent correlation between percent survival and history of manuring. Water quality was similar and acceptable for tilapia in each of the six ponds. The data indicated that a stocking rate of 50 hogs/ha can result in high fish yields; and that the history of a pond's experimental use influences subsequent experimental results.     

锌胁迫对海洋小球藻生长和金属硫蛋白诱导的影响

研究锌离子胁迫对海洋小球藻生长和金属硫蛋白诱导的影响,当小球藻达到对数生长期,用不同离子浓度(5、10、20、50和100μmol/L)的锌盐(氯化锌、柠檬酸锌、乙酸锌和葡萄糖酸锌)分别进行胁迫培养,通过测定小球藻的生物量和锌结合金属硫蛋白含量,考察锌胁迫对海洋小球藻的生物量、热稳定蛋白含量以及锌结合金属硫蛋白含量的影响。结果显示,当浓度分别小于5和10μmol/L时,柠檬酸锌和氯化锌对小球藻生长无显著抑制作用;而浓度为5μmol/L时,乙酸锌和葡萄糖酸锌对小球藻生长即产生显著抑制,且抑制作用皆随锌离子浓度的增加而增大。与对照组相比,4种锌盐胁迫3 d后小球藻产生的热稳定蛋白含量极显著增加,其中以锌离子浓度为50μmol/L的葡萄糖酸锌对小球藻胁迫产生的热稳定蛋白含量最高,达到34.5 mg/g(湿藻泥)。同样在此浓度的葡萄糖酸锌胁迫下,小球藻诱导产生的锌结合金属硫蛋白的含量最高。研究表明,用锌离子浓度为50μmol/L的葡萄糖酸锌对小球藻胁迫培养,诱导产生的锌结合金属硫蛋白含量达到最高。     

Growth of 0-group turbot (Scophthalmus maximus L. 1758) fed on artificial diets

Group-0 turbot Scophthalmus maximus L. were fed on artificial diets for 13 months, at 15° C. Partially defined diets containing about 40% protein were used and fish were fed once per day with moist pellets.The mean weight of the fish, at the beginning of the experiment, was 3.5 g. During the first 6 months, a fish gained 15 g weight on average, and 40 g in the following 6 months. The final mean weight was 62 g, and the final mean total length, 15.3 cm. The daily growth rate was 0.7% and the protein efficiency ratio (P.E.R.) ranged between 1.4 and 2.1.For fish fed on natural food at 15° C, the results were similar for the first 9 months. Subsequently, these fish grew faster than those fed artificial diets.     

Growth response of Tilapia zillii fingerlings fed isocaloric diets with variable protein levels

Six purified casein diets within a range of 21–53% crude protein were fed for 3 weeks to young tilapia (Tilapia zillii) to determine the optimum protein requirement and protein: energy ratio for growth. Growth rate increased proportionally to protein level of the diet to an incorporation rate of about 35%. Beyond this a gradual retardation in growth rate was observed. The diet containing about 30% crude protein with a protein: energy ($\text{P}\text{E}$) ratio of 81, however, appeared to be more efficiently utilized by the fish in terms of protein deposition and energy retention than diets with higher levels of crude protein. These results indicate that Tilapia zillii requires about 35% protein in the diet for optimum growth while 30% for the maximum bodily protein deposition when casein is used as the sole source of protein. All six diets, however, showed an excellent feed conversion. Protein efficiency ratio (PER) decreased with the increase in protein in the diet.     

光周期对卤虫摄食、生长和存活的影响

在不同光周期（０Ｌ：２４Ｄ、６Ｌ：１８Ｄ、１２Ｌ：１２Ｄ、１８Ｌ：６Ｄ和２４Ｌ：０Ｄ）下培养河北大清河盐场的卤虫,结果表明：卤虫的摄食率有随着光周期缩短而下降的趋势。大清河盐场的卤虫在不同光周期下的生长速度无显著差异,但成活率差异显著,６Ｌ：１８Ｄ组的成活率最高。建议在短光周期下培养卤虫。