小球藻的作用及优劣鉴别

小球藻(Chlorella)为绿藻门、小球藻属、普生性单细胞绿藻,是一种球形或椭圆形单细胞藻类,直径3～8微米,是地球上最早的生命之一,出现在20多亿年前,基因始终没有变化,其光合作用能力非常强,是其他植物的几十倍。     

小球藻的调水功能及使用案例

正小球藻为绿藻门、小球藻属普生性单细胞绿藻,是一种球形单细胞藻类,直径3～8微米,是地球上最早的生命之一,出现在20多亿年前,是一种高效的光合植物,以光合自养生长繁殖,分布极广。世界各地均有分布,多生活于较小浅水水域,也有海产种类。天然条件下个体较少,人工培养可大量繁殖。目前世界上已知的小球藻约10种,加上其变种可达数百种之多。小球藻广泛分布于自然界,以淡水水     

海产珍稀经济动物幼体的适口饵料小球藻

海产珍稀动物幼体的生物饵料适口是人工育苗成功的关键所在。作为人工培养的优良饵料生物应具备下列条件：1．个体大小及在水中的运动和分布应适于养殖动物摄食；2．营养丰富且容易被养殖动物消化吸收；3．饵料生物的代谢产物对养殖动物无毒；4．对环境的适应力强，生长、繁殖迅速，易于大量培养。小球藻属绿藻门、绿藻纲、绿球藻目、小球藻科、小球藻属。适生于海水环境中的代表种如盐生小球藻（ChlorellasalinaButcher），该藻藻体为圆球形，单细胞，细胞直径为4～7微米，具有明显的细胞壁，壁薄而光滑。叶绿体杯形，几乎充满整个细胞，…     

小球藻在池塘养殖中的调水作用

正一、小球藻概述小球藻是一类普生性单细胞藻类,属于绿藻门、绿藻纲、小球藻属,世界各地均有分布,多生活于淡水浅水处,海产种类少。目前世界上已知的小球藻有十几种,加上它的变种可达数百种之多。我国常见的种类有蛋白核小球藻、椭圆小球藻、普通小球藻等,其中蛋白核小球藻的蛋白质含量高,营养价值居各种小球藻之首。     

两株蛋白核小球藻 rbcS cDNA 全序列的克隆和分析

以2株蛋白核小球藻(Chlorella pyrenoidosa)F-9和820为实验材料,根据已知绿藻rbcS基因设计简并引物,分别克隆到2条245bp的cDNA片段,以此片段为基础使用cDNA末端快速扩增(RACE)技术,获得了2条长度分别为861bp和907bp的rbcS基因。序列分析表明,蛋白核小球藻F-9和820的rbcS分别编码181和184个氨基酸,编码区具有与高等植物rbcS保守序列YYDGRYWTMWKLPMFG相类似的结构,起始密码子附近有Kozak保守序列(A/GXXATGG),3′非翻译区有加尾信号TGTAA。同源性分析结果表明,F-9与蛋白核小球藻(GenBank登录号BAE48226)的相似性最高(91%),而F-9与820、F-9和普通小球藻(C.vulgaris)的相似性分别为64%和50%。这2条rbcS基因与其他绿藻和高等植物也表现了广泛的同源性,但相似性不高。该研究旨在为rbcS基因的功能和表达研究奠定基础。     

雨生红球藻积累虾青素的分子基础与人工诱导调控研究进展

正雨生红球藻(Haematococcus pluvialis)是一种单细胞微藻,在分类学上属绿藻门、绿藻纲、团藻目、红球藻科、红球藻属[1]。其生活史主要分为游动细胞阶段和不动细胞阶段。在外界环境条件适宜时,微藻以游动状态存在,依靠两条顶生、等长的鞭毛运动,这一阶段的细胞大多呈绿色,此时微藻生长旺盛,生物量积累迅速[2]。当雨生红球藻处于高光照度、高盐度及营养缺乏的胁迫条件时,细胞以红色厚壁孢子形式存在,此阶段细胞鞭毛脱落,运动能力丧失,开始逐渐合成并积累虾青素[3]。     

菹草对小球藻和卵囊藻的形态化感效应研究

研究生态修复过程中沉水植物对藻类的影响,为水生态修复提供理论依据。选用常见沉水植物菹草(Potamogeton crispus)研磨液为培养液,对常见绿藻普通小球藻(Chlorella vulgaris)和卵囊藻(Oocystis sp.)开展室内模拟试验培养,通过绿藻生长和形态特征的变化,了解新鲜菹草是否对普通小球藻和卵囊藻存在一定的化感效应。研究结果表明,菹草对普通小球藻和卵囊藻的生长均未呈现显著抑制效应;普通小球藻对菹草具有形态响应,一次性添加的菹草研磨液在试验初期显著促进普通小球藻群体的形成,随着时间的推移,群体普通小球藻逐渐裂开转化为小群体或者是单细胞;试验结果还表明,菹草对卵囊藻形态无显著影响。     

高度不饱和脂肪酸对水生动物生长、发育和繁殖的影响与机理

正高度不饱和脂肪酸是多不饱和脂肪酸中具有二十个碳原子以上,含3个或3个以上双键的脂肪酸~[1-4],主要有花生四烯酸(C20:4n-6)、二十二碳六烯酸(C22:6n-3)和二十碳五烯酸(C20:5n-3)等~[5-12]。高度不饱和脂肪酸影响机体脂类代谢~[13]、基因表达~[14-15]、细胞膜功能~[16]、机体免疫~[17-18]及血液生理生化特性~[19-20]等,对水生动物的生长、发育和繁     

基于香溪河背景下小球藻对不同形态氮素吸收动力学研究

选取香溪河绿藻水华爆发时优势藻种—小球藻（Chlorella）,经过分离纯化后作为实验原材料,分别检测了培养液中氨氮和硝氮的浓度,分析了小球藻对氨氮和硝氮吸收动力学特征以及不同氮素对其吸收速率的影响。实验表明,当氨氮浓度为11.62～2.97 mg/L,实验第2~3天时,小球藻氨氮去除效率不断加强,达到74.44%;当硝氮浓度为10.55～0.047 mg/L;实验第2~5天时,硝氮去除效率也不断加强,达到96.92%。无论是氨氮还是硝氮的培养条件下,小球藻在实验初始阶段都保持着较高的吸收速率,分别为1.44 mg/h和0.97 mg/h,随着培养介质中氮素浓度不断下降,其吸收速率也随之下降,其中用氨氮培养的小球藻在第3天达到最大吸收速率,为1.44 mg/h;用硝氮培养的小球藻在第4天达到最大吸收速率,为0.97 mg/h。小球藻对氨氮和硝氮的最大半饱和常数分别为2.85 mg/L和5.09 mg/L,表明单一氮源培养小球藻时,小球藻对氨氮更具有亲和力。实验结果为研究小球藻对氮素吸收速率从而控制小球藻生长提供理论依据,有助于通过调整、改变营养盐的输入通量及输入类型抑制小球藻繁殖,避免绿藻水华的发生。     

浒苔资源利用的研究进展及应用前景

浒苔(Enteromorpha prolifera)俗称苔条、青海苔,为绿藻门、石莼科、浒苔属大型海藻类。藻体直立,管状中空或藻体柄部和边缘部分呈中空,管状部分由单层细胞组成。藻体单条或有分枝,圆柱形,有时部分扁压。藻体基部形成固着器。欧、美、亚洲黄海和日本海等海域中均有广泛分布[1]。     

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.     

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.     

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.