氧、光照时间、pH等理化因子影响光合细菌生长的研究

用正交试验设计研究氧、光照时间、pH值等理化因子对荚膜红假单胞光合细菌生长状况。研究结论，荚膜红假单胞菌适宜生长在光照充足的有氧条件下，初始培养基的pH值最好中性偏酸，以使其在整个生长过程中呈良好的态势。     

高活性光合细菌荚膜红假单胞菌培养特性初探

从洛河水中进行了光合细菌的分离，得到一株细胞活性高的荚膜红假单胞菌JM12，并对其培养条件进行了初步摸索。结果表明：该菌适宜在pH值6～7，盐浓度0％～3％，温度25℃～35℃以及有光照条件下生长。     

光合细菌的计数方法--半固体试管法

光合细菌是一大类能在厌氧条件下进行不产氧光合作用的细菌的总称,包括红螺菌科、着色菌科、绿硫菌科和绿色丝状菌科,由于它有能利用硫化氢、氨氮、有机酸等小分子有机物快速生长且菌体本身具有营养丰富、无毒无害等特点,因而在水产养殖上得到了广泛应用。目前水产养殖中用的光合细菌主要是红螺菌科的光合细菌,如沼泽红假单胞菌、荚膜红假单胞菌、球形红菌等,常用来净化水质、防治疾病和促进水产动物的生长,效果比较明显。然而长期以来,光合细菌水产制剂却没有一个统一的质量标准,造成产品质量参差不齐,甚至时有掺假使杂现象发生,严重危害到…     

光合细菌菌种的分离、富集培养、纯化和菌种鉴定及净化水质的研究

光合细菌一般生长在湖底土、河流底土、海底土和水田等地，笔者选择有机物污染较为严重的东平湖畔的河流底土，经富集培养、纯化，最后经菌种鉴定获得了沼泽红假单胞菌、胶质红假单胞菌、球形红假单胞菌和绿色红假单胞菌４株净化养鱼池水质较为理想的菌株。１试验材料和方法１．１富集用培养基NH４Cl１克，MgCl２０．２克，酵母膏０．１克，K２HPO４０．５克，NaCl２克，水９００毫升，灭菌。经过滤灭菌的NaHCO３５克／５０毫升水；５０毫升经过滤灭菌的酒精、戌醇或４％的丙氨酸，用过滤灭菌的０．１摩／升H３PO４调pH值至７．０。…     

光合细菌菌剂和沼泽红假单胞菌对实验水体氮磷营养盐和微生物群落的影响

为比较光合细菌菌剂与沼泽红假单胞菌(Rhodopseudomonas palustris)的生理生态特性,分析了不同初始菌量的菌剂PG和菌株PSB-1对实验水体氨氮(NH_4~+-N)、亚硝氮(NO_2~--N)、硝氮(NO_3~--N)和活性磷(PO_4~(3-)-P)的降解效果,通过高通量测序分析了菌剂PG的优势菌组成及实验结束时水体细菌数量和微生物群落组成。结果显示,菌剂PG组对实验水体的PO_4~(3-)-P、NO_3~--N和NO_2~--N有一定的降解作用,其最大降解率分别为40.98%、28.28%和20.12%。菌株PSB-1组仅对实验水体的NO_2~--N和PO_4~(3-)-P有一定的降解效果,其最大降解率分别为14.19%和9.88%。菌剂PG的主要优势菌为红假单胞菌属(Rhodopseudomonas sp.)。实验7 d后实验组水体细菌数量和微生物群落结构发生变化,水体细菌数量增长,形成以异养细菌为优势菌的菌群结构。结果表明光合细菌菌剂PG对水质因子的降解效果优于沼泽红假单胞菌PSB-1,但与报道的高效光合细菌菌株的降解能力存在一定差距。     

粘稠性荚膜红假单胞菌对黄沙鳖稚鳖水质及生产性能的影响

探讨了荚膜红假单胞菌对黄沙鳖稚鳖水质及生产性能的影响.结果表明:使用荚膜红假单胞菌后,试验池与对照池相比较,水体中的溶氧量提高了31.17％,平缓pH值波动,显著降低水中氨氮含量,下降幅度达74.08％,加快了水中氨氮转化量,减少了氨氮的毒害作用.成活率提高了9.5％、重量增重了9.79 kg,其发病率比后者降低30....     

海洋光合细菌筛选及其对养殖水体修复效果的测定

集约化投饵型养殖会导致养殖区域底部环境持续恶化,限制了水产养殖的可持续发展。对采自威海金海滩排污口附近污泥中的海洋光合细菌进行了富集、分离和初步鉴定,模拟自然养殖环境,选取优势菌株进行池塘底泥处理试验(上层水体,下层底泥),分析比较两株菌对底泥的改良效果;试验共获得两株优势光合细菌PSB1和PSB2,分属于红假单胞菌属(Rhodopseudomonas)和小红卵菌属(Rhodovulum)。底泥处理试验结果显示:PSB1和PSB2都可以稳定水体pH,降解水中的硫化物、氨氮和化学耗氧量(COD_(Mn))。PSB1处理底泥最佳效果为:添加1‰的PSB1,水体中pH在6.98～7.33,底泥中COD_(Mn)、硫化物、氨氮和NO~-_2-N降解率分别为92.91%、79.61%、97.00%和73.56%。研究表明,光合细菌可以促进改善水质、维持下层水体的良好水质,在水产养殖中具有良好的应用前景。     

粘稠性荚膜红假单胞菌对黄沙鳖稚鳖水质及生产性能的影响

通过对黄沙稚鳖养殖池进行pH值、DO、氨氮、亚硝酸盐和COD水质指标的测定和比较，探讨荚膜红假单胞菌对黄沙鳖稚鳖养殖池水质及生产性能的影响。结果表明：使用英膜红假单胞菌后，试验池与对照池相比较，水体中的溶氧量提高了31．17％，pH值平缓波动，显著降低水中氨氮含量，下降幅度达74．08％，加快了水中氨氮转化量，减少了氨氮的毒害作用，成活率提高了9．5％，重量增加了9．79kg，发病率降低30．33％，治愈率高达19．5％。     

3种细菌对小球藻生长和脱氮除磷效率的影响

鉴于水资源日益紧缺且水污染问题日渐加剧的现状,藻菌共生系统作为一种节能环保的污水处理方式,有助于提高污水处理效率。通过人工模拟城市污水,选取3种污水处理中常用细菌地衣芽孢杆菌(Bacillus licheniformis)、枯草芽孢杆菌(Bacillus subtilis)和沼泽红假单胞菌(Rhodopseudomonas palustris)与小球藻构建藻菌共生系统,探究了不同细菌对蛋白核小球藻(Chlorella pyrenoidosa FACHB-5)生长以及污水脱氮除磷效率的影响。结果显示,在3种藻菌共生系统中,地衣芽孢杆菌为小球藻促生长菌,而枯草芽孢杆菌对小球藻生长有抑制作用,沼泽红假单胞菌对小球藻生长无显著影响(P>0.05),且沼泽红假单胞菌的生长受到小球藻的显著抑制(P<0.05)。在3个共生系统中,地衣芽孢杆菌-小球藻共生系统中小球藻生物量最高,第2天水体的总氮和总磷去除率分别达到79.84%和83.48%,显著高于小球藻单独培养试验组(P<0.05)。研究表明,3种藻菌共生系统中,细菌与微藻间的关系具有特异性,应选择适宜的促生菌与微藻共培养,合适的藻菌共生系统可提高水体总氮和总磷的去除率。     

固定化浓缩光合细菌对河蟹的促生长影响

根据昆山巴城地区以河蟹为主要养殖品种的特点,我们应用固定化浓缩光合细菌(PSB)对其进行了促生长试验。试验使用的菌种主要由红假单胞菌属的球形红假单胞菌和荚膜红假单胞菌组成,培养方法参照Weaver等(l975)的方法,扩大培养至菌体密度达5×l09个/毫升时收获,6000转/分离心,弃去上层清液,收获PSB浓缩菌体密度达5×l010个/毫升,作为试验用菌液。PSB的固定化采用吸附法,将离心后收集的l0倍浓度PSB浓缩液以硅藻土为吸附剂吸附在表面使其固定化。使用前将固定化浓缩PSB在营养液中活化24小时,使硅藻土内PSB的活性得到恢复和强化。试验分…     

Association between the interannual variation in the oceanic environment and catch rates of bigeye tuna (Thunnus obesus) in the Atlantic Ocean

The environmental processes associated with variability in the catch rates of bigeye tuna in the Atlantic Ocean are largely unexplored. This study used generalized additive models (GAMs) fitted to Taiwanese longline fishery data from 1990 to 2009 and investigated the association between environmental variables and catch rates to identify the processes influencing bigeye tuna distribution in the Atlantic Ocean. The present findings reveal that the year (temporal factor), latitude and longitude (spatial factors), and major regular longline target species of albacore catches are significant for the standardization of bigeye tuna catch rates in the Atlantic Ocean. The standardized catch rates and distribution of bigeye tuna were found to be related to environmental and climatic variation. The model selection processes showed that the selected GAMs explained 70% of the cumulative deviance in the entire Atlantic Ocean. Regarding environmental factors, the depth of the 20 degree isotherm (D20) substantially contributed to the explained deviance; other important factors were sea surface temperature (SST) and sea surface height deviation (SSHD). The potential fishing grounds were observed with SSTs of 22–28°C, a D20 shallower than 150 m and negative SSHDs in the Atlantic Ocean. The higher predicted catch rates were increased in the positive northern tropical Atlantic and negative North Atlantic Oscillation events with a higher SST and shallow D20, suggesting that climatic oscillations affect the population abundance and distribution of bigeye tuna.     

Growth performance,digestive enzyme activity and immune response of Japanese sea bass,Lateolabrax japonicus fed with fructooligosaccharide

In this experiment, a feeding trial was performed to determine the effects of fructooligosaccharide (FOS) on growth performance, digestive enzyme activity and immune response of Japanese sea bass, Lateolabrax japonicus juveniles (initial weight 38.3 ± 0.5 g), and the fish were examined following feeding with six levels of FOS (0, 0.5, 1, 2, 4 and 6 g/kg) for 28 days. Significant enhancement of weight gain (WG) and specific growth rate (SGR) was found in fish fed 1 g/kg FOS incorporated diets (p < .05), while the feed conversion ratio (FCR) in the 1, 2 g/kg FOS groups reduced significantly compared with the control (p < .05). Besides, the crude lipid in the 4, 6 g/kg FOS groups increased significantly compared with the control (p < .05). On the other hand, the erepsin and lipase activities significantly elevated in intestine of fish fed 2 g/kg FOS (p < .05) and the lysozyme activity in serum of fish fed 2 g/kg FOS were significantly higher than that in the control (p < .05). Moreover, the alkaline phosphatase activities in serum of fish fed 0.5, 1, 2 g/kg FOS were significantly higher than in control (p < .05). Regression analysis showed that the relationships between dietary FOS levels and either SGR, FCR, erepsin or lysozyme activities were best expressed by regression equations, and the optimal inclusion levels are 1.37, 1.80, 3.06, 3.11, 1.93 and 1.80 g/kg for SGR, FCR, erepsin, lipase, lysozyme and total superoxide dismutase activities, respectively. Overall, this study revealed that FOS incorporated diets could beneficial for L. japonicus culture in terms of increasing the growth, digestion and immune activities. Under the present experimental condition, the optimal supplementary level of FOS in the diet of L. japonicus is 1–3 g/kg.     

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.     

Involvement of gonadal steroids in final oocyte maturation of white perch (Morone americana) and white bass (M. chrysops): in vivo and in vitro studies

Plasma estradiol-17 (E₂), testosterone (T), 17,20-dihydroxy-4-pregnen-3-one (DHP) and 17,20,21-tri-hydroxy-4-pregnen-3-one (20-S) levels were measured by radioimmunoassay (RIA) in white perch (Morone americana) and white bass (M. chrysops) that were induced to undergo final oocyte maturation (FOM) with human chorionic gonadotropin (hCG). Plasma DHP levels increased in females of both species in association with oocyte germinal vesicle migration (GVM) and germinal vesicle breakdown (GVBD) and decreased thereafter. Plasma 20-S levels also increased with oocyte GVM in white bass, but were several-fold lower than DHP levels. Circulating E₂ and T levels were greatest during GVM and GVBD in both species and decreased to low levels during oocyte hydration and ovulation. Follicles from white perch and white bass which received a priming injection of hCG in vivo, produced both DHP and 20-S in vitro after exposure to hCG and their oocytes underwent GVBD. Ovarian incubates from unprimed fish of either species produced only E₂ and T and their oocytes did not complete GVBD. Oocytes from unprimed bass, but not perch, matured when follicles were exposed to hCG in vitro. Both trilostane and cycloheximide blocked in vitro production of DHP and 20-S and oocyte GVBD by white perch follices. DHP and 20-S were equipotent inducers of FOM in the GVBD bioassay. None of several other structurally-related steroids tested were effective within a physiological range of concentrations. These results indicate a role for DHP and 20-S in the control of FOM in white perch and white bass.     

Cardiac,ventilatory and metabolic responses of two ecologically dissimilar species of fish to waterborne cyanide

Changes in heart rate, ventilatory activity and oxygen consumption were determined in trout (Salmo gairdneri) and brown bullhead catfish (Ictalurus nebulosus) during exposure to a steadily increasing concentration of waterborne cyanide selected to produce death in 8–9 hours for each species. The lethal cyanide concentration for the bullheads was an order of magnitude higher than for trout. Trout developed an immediate and gradually increasing bradycardia throughout the exposure period. Cyanide produced tachycardia in the bullhead followed by a gradual onset of bradycardia as the concentration of cyanide was raised. Pericardial injection of atropine (a muscarinic cholinergic antagonist) indicated that bradycardia in the trout was due initially to increased vagal tone but later due to the direct effect of cyanide on the heart. Hyperventilation in the trout persisted throughout the exposure period, although the rate and amplitude fluctuated and was variable between individual fish. During the last hour of exposure (highest cyanide concentration), ventilation was characterized by rapid, shallow breaths followed by a sudden respiratory arrest. The bullheads exhibited hyperventilation during the first 3 hours of exposure followed by a gradual, linear drop in ventilation rate and amplitude until death occurred. Cardiac and ventilatory responses in both species were attributed to stimulation of central and peripheral chemoreceptors by cyanide. Evidence is presented which suggests the initial response in the bullheads was due, at least in part, to gustatory stimulation by the cyanide. Oxygen consumption of the trout remained above pre-exposure levels for the majority of the test period. Oxygen consumption in the bullhead paralleled the changes in heart and ventilatory rates. Whole-body lactate levels of fingerlings of both species during cyanide exposure were measured to estimate the extent of anaerobiosis. Whole-body lactate levels were much greater in the bullheads than the trout, indicating a higher capacity for anaerobiosis, possibly due to a greater fuel supply. Overall, the trout responded to cyanide in a manner similar to that produced by environmental hypoxia whereas the bullheads experienced a gustatory stimulus which masked the hypoxia-like response.     

An overview of stress physiology of fish transport: changes in water quality as a function of transport duration

This study brings an integrated analysis about the relationship between water deterioration and its physiological consequences in live fish transport. The analysis was focused on the transport water and its deterioration, and physiological challenges imposed on the fish. Usual commercial handling procedures employed to mitigate fish stress during transport were discussed. Future topics of research for the establishment of safer fish transport protocols were proposed. Transport was classified into short (≤8 h) or long transport (>8 h). The main issue in short transports should be the prevention of water pH reduction, while in long transports it is the increase in ammonia. Plasma cortisol is the most employed marker for stress and is acutely elevated upon short episodes of transport, but remains elevated even in long‐transport events. Plasma glucose is perhaps a better marker for handling stress. Plasma lactate, pH, osmolality CO₂ and ions should be more often evaluated. Plasma Na⁺ and Cl^‐ are very useful markers of acidosis, due to their respective exchange for H⁺ and , for acid–base regulation. The establishment of species‐specific transport protocols should be preceded by such combined analyses of water and physiological parameters.     

Are hatchery‐reared abalone naïve of predators? Comparing the behaviours of wild and hatchery‐reared northern abalone,Haliotis kamtschatkana (Jonas, 1845)

Abalone populations have declined worldwide, generating interest in enhancement using hatchery‐reared individuals. In many cases, such restoration efforts have met with limited success due to high predator‐induced mortality rates. Furthermore, the mortality rates of outplanted hatchery abalone are often considerably higher than for wild individuals. This study uses northern abalone (Haliotis kamtschatkana) as a case study to determine whether hatchery‐reared abalone behave differently than their wild counterparts. In the field, outplanted hatchery‐reared abalone were significantly less responsive than wild abalone, in terms of number of abalone responding and intensity of response, to nearby movement and to physical contact with an inert probe. Also, when encountering a cue to which all abalone responded (a seastar predator), hatchery‐reared individuals remained subdued. Anti‐predator behavioural deficits in hatchery‐reared abalone were more pronounced in 4‐year‐old individuals than in 1‐year‐old individuals, suggesting an influence of either age or amount of time spent in the hatchery environment. These behavioural differences are expected to increase the vulnerability of hatchery‐reared abalone to predators, and are likely a major cause of their elevated predator‐induced mortality when outplanted.     

Effects of cadmium on the kinetics of calcium uptake in developing tilapia larvae, Oreochromis mossambicus

The toxic effects of Cd²⁺ on Ca²⁺ influx kinetics in developing tilapia (Oreochromis mossambicus) larvae were evaluated. Addition of 20 µg l^-1 of Cd²⁺ to the environment of 0 and 3 day-old larvae competitively inhibited the Ca²⁺ uptake within 4h resulting in a great increase in K_m values for Ca²⁺ influx (19.3 and 17.4 fold, respectively) as compared with their respective controls. Consequently, the actual Ca²⁺ influx of larvae in solutions of 0.2 mM Ca²⁺ are suppressed by 32–45%. Also, 3 day-old larvae were more sensitive to internally accumulated Cd²⁺ than 0 day-old larvae. Although the Ca²⁺ influx in 0 and 3 day-old larvae may be restored to the levels of their respective controls with 24h of being transferred to a 20 µg l^-1 Cd²⁺ solution, total body Ca²⁺ content was significantly reduced in 3 day-old larvae. Increased Ca²⁺ uptake efficiency ensures sufficient Ca²⁺ for normal growth. However, rapid increase in Ca²⁺ influx after hatching also leads to higher Cd²⁺ uptake. Exposure to Cd²⁺ will lead to a drop in body Ca²⁺ content resulting in retardation of larval growth. Therefore, we conclude that if Ca²⁺ uptake is interfered with at this critical stage of development, larvae will not be able to maintain normal levels of body Ca²⁺ and will show signs of Cd²⁺ poisoning.     

Migratory dynamics of stream-spawning longnose gar (Lepisosteus osseus)

Abstract– Literature evidence suggests that lake-dwelling longnose gar (Lepisosteus osseus) enter tributary streams to spawn, Until the present study, the dynamics of this breeding migration had never been investigated quantitatively. During the summers of 1991 and 1992, longnose gar were captured as they entered Weaubleau Creek, Missouri, a tributary of Harry S. Truman Reservoir. The in-stream spawning migration began in early April and ended in late May, and was positively correlated with stream flow and water level, and negatively correlated with water temperature. In-stream residence times ranged from 15 to 94 days, with males exhibiting longer residence times than females. Once in-stream, longnose gar travelled as far as 10 km upstream and occupied certain pools at greater relative frequencies. Although the reason for this preferential utilization is not completely understood, it may relate to pool depth and riffle proximity. Longnose gar disperse from the spawning stream great distances, with gar captured in Weaubleau Creek being recaptured up to 48 km away. This information should provide fisheries biologists the means to consider the reproductive ecology of this species in their conservation and management decisions.     

Nutritional regulation of hepatocyte fatty acid desaturation and polyunsaturated fatty acid composition in zebrafish (Danio rerio) and tilapia (Oreochromis niloticus)

The desaturation and elongation of [1-¹⁴C]18:3n-3 was investigated in hepatocytes of the tropical warm freshwater species, zebrafish (Danio rerio) and Nile tilapia (Oreochromis niloticus). The hepatocyte fatty acid desaturation/elongation pathway was assayed before and after the fish were fed two experimental diets, a control diet containing fish oil (FO) and a diet containing vegetable oil (VO; a blend of olive, linseed and high oleic acid sunflower oils) for 10 weeks. The VO diet was formulated to provide 1% each of 18:2n-6 and 18:3n-3, and so satisfy the possible EFA requirements of zebrafish and tilapia. At the end of the dietary trial, the lipid and fatty acid composition was determined in whole zebrafish, and liver, white muscle and brain of tilapia. Both zebrafish and tilapia expressed a hepatocyte fatty acid desaturation/elongation pattern consistent with them being freshwater and planktonivorous fish. The data also showed that hepatic fatty acid desaturation/elongation was nutritionally regulated with the activities being higher in fish fed the VO diet compared to fish fed the FO diet. In zebrafish, the main effect of the VO diet was increased fatty acid Δ6 desaturase activity resulting in the production of significantly more 18:4n-3 compared to fish fed the FO diet. In tilapia, all activities in the pathway were greater in fish fed the VO diet resulting in increased amounts of all fatty acids in the pathway, but primarily eicosapentaenoic acid (EPA; 20:5n-3) and docosahexaenoic acid (DHA; 22:6n-3). However, the fatty acid compositional data indicated that despite increased activity, desaturation of 18:3n-3 was insufficient to maintain tissue proportions of EPA and DHA in fish fed the VO diet at the same level as in fish fed the FO diet. Practically, these results indicate that manipulation of tilapia diets in commercial culture in response to the declining global fish oil market would have important consequences for fish fatty acid composition and the health of consumers. Scientifically, zebrafish and tilapia, both the subject of active genome mapping projects, could be useful models for studies of lipid and fatty acid metabolism at a molecular biological and genetic level. This revised version was published online in August 2006 with corrections to the Cover Date.