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小球藻( Chlorella )是一种单细胞真核藻类,属绿藻门、绿藻纲、绿球藻目、小球藻科、小球藻属 [1] 。作为最早开发的真核微藻之一,具有高营养价值、生长快速、结构简单、易工业化集成等显著优点。其细胞形态为球形或椭圆形,直径3~12 μm,呈单生或聚集成群状生长 [2] ,分布广泛,多见于淡水、咸水和土壤中。作为地球上最早的生命之一,小球藻基因比较稳定,至今未见有关其基因自发突变的报道。因其富含蛋白质、脂质、维生素、活性代谢产物等多种营养物质而被公认为具有高附加值和医疗保健作用,已经被广泛应用于保健食品 [3] 、水产养殖 [4] 、生物能源 [5] 等方面,关于小球藻生物技术的研究主要集中在基因组学 [6] 、分子遗传学 [7] 、代谢机理 [8] 、大规模培养 [9] 等方向。 相似文献
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于 2018 年 6–8 月对雅砻江下游干支流的着生藻类进行调查, 并以其主要支流安宁河为代表, 重点研究河流纵向梯度下着生藻类的空间分布格局(102°6′6″E, 28°46′21″N~101°49′22″E, 26°38′38″N)。结果显示: 雅砻江下游共鉴定着生藻类 95 种, 以硅藻(Bacillariophyta)、绿藻(Chlorophyta)和蓝藻(Cyanophyts)为主。雅砻江干流物种数最多, 优势种为曲壳藻属未定种 (Achnanthes sp.)、异极藻属未定种 (Gomphonema sp.)和胶质细鞘丝藻(Leptolyngbya gelatinosa)等; 其次为安宁河干流, 优势种为曲壳藻属未定种和细小隐球藻(Aphanocapsa elachist); 安宁河支流物种丰富度最低, 优势种主要为曲壳藻属未定种、胶质细鞘丝藻和异极藻属未定种等。着生藻类平均密度呈雅砻江干流＜安宁河支流＜安宁河干流趋势。沿着河流纵向梯度, 安宁河干流物种丰富度逐渐增加, 硅藻密度比例渐趋下降, 而绿藻和蓝藻的比例却逐渐升高。水温、浊度和底质类型与雅砻江下游流域着生藻类多样性和空间分布格局密切相关; 流速和海拔是影响纵向梯度下安宁河着生藻类分布的主要环境因子。本研究旨在为高原山区河流的水生生物多样性保护提供依据, 并为该流域食物网构建提供基础资料。 相似文献
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凡纳滨对虾低盐度养殖池浮游藻类群落研究 总被引：15，自引：0，他引：15
在44口凡纳滨对虾低盐度养殖池中共鉴定藻类7门62属113种,蓝藻26种,绿藻54种,硅藻14种,裸藻11种,隐藻3种,甲藻4种,金藻1种。绿藻门种类最多,占藻类种类数的47·8%,其次为蓝藻门占23·0%,硅藻占12·4%,裸藻占9·7%。优势种主要为蓝藻,典型优势种有螺旋藻(Spirulinasp.),假鱼腥藻(Pseudoanabaenasp.),弯形尖头藻(Raphidiopsis curvata),针状蓝纤维藻(Dactylococcopsis acicularis)等,其中螺旋藻的优势度平均达到50%,为主要优势种。常见的绿藻有栅藻(Scenedesmusp.),衣藻(Chlamydomonassp.),小球藻(Chlorella vulgaris)等;常见的硅藻为梅尼小环藻(Cyclotella meneghinian),卵形隐藻(Cryptomonas ovata)、啮蚀隐藻(C.erosa)和绿裸藻(Euglenavirdis)在虾池中比较常见。养殖池中浮游藻类的种类数平均为43±9种,多样性指数平均为2·19±0·56,个体数量平均为1·45±0·87×108个/L;藻类的种类、数量及生物量表现为养殖前期低后期高的特征,而多样性表现相反,藻类的组成直接影响对虾的生长。 相似文献
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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。 相似文献
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正三代虫科属扁形动物门、单殖吸虫纲、多钩亚纲、三代虫目[1],是一类常见的鱼类体外寄生虫,主要寄生在200种硬骨鱼[2]及少数软体类和两栖类的体表[3-4]。全世界记录的三代虫已超过450种,潜在总物种数可能超过20 000种[5-8]。三代虫科国内记录了3属60种[9-12],其中三代虫属(Gyrodactylus)共58种、薄片吸虫属(Laminiscus)和拟三代虫属(Paragyrodactylus)各1种。三代虫的繁殖方式 相似文献
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2006年10月对升金湖中的浮游藻类进行了调查,分析了浮游藻类分布规律及优势种的组成、浮游藻类多样性分布和浮游植物与环境因子的关系;利用多种多样性评价指数对水体的污染情况进行了评价.结果表明,升金湖有浮游藻类8门、101属、358种.浮游藻类的密度差异明显,介于81.7×104～6 427×104个/L,主要由蓝藻、绿藻、硅藻、甲藻、裸藻、隐藻、黄藻和金藻等组成,以蓝藻门的鞘丝藻、平裂藻和鱼腥藻,硅藻门的小环藻、针杆藻和直链藻,绿藻门的栅藻和盘星藻为优势种.各种评价指数显示,水体大部分区域的污染程度较为严重,整个湖泊属富营养化范畴. 相似文献
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(1)水色发暗或浑浊等现象:这种情况多发生在冬棚淡水养殖区,中后期水中绿藻及蓝藻大量繁殖,水色多呈深绿色或暗绿色。如果蓝绿藻大量繁殖,池水过浓,可用漂白粉0.5～1克/米3杀除部分藻类,但用量一定要准确,以免藻类大量死亡影响虾池水质。由于水中有些藻类大量生长,必需微量元素缺乏,影响到其他藻类的正常繁殖生长,而出现藻类老化、死亡,或者某些 相似文献
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为探讨短期内Nualgi营养素对池塘水质和藻类群落结构的影响,本研究在池塘中的不透水有底帆布围隔内共设计了4个试验组,依次分别添加Nualgi营养素(M1组)、补充硅藻藻种(M2组)、同时添加Nualgi营养素并补充硅藻藻种(M3组)、不做任何处理的空白对照(C组)。经过近一个月的试验,结果显示:各组的pH值、DO、TN、TP之间没有显著性差异;Nualgi可以显著降低水体中IP的含量,M1组和M3组的IP显著低于M2组和C组;M1组、M2组和M3组中的NH_4~+-N、NO_2~--N和CODMn含量显著低于C组,表明Nualgi和硅藻藻种都可以显著降低水体中NH_4~+-N、NO_2~--N和CODMn的含量,对养殖水质具有显著的调控效果。试验各组的藻类种群极为丰富,试验期间共检出浮游植物7门109属186种,其中绿藻门47属86种,硅藻门26属48种,蓝藻门18属27种,裸藻门11属17种,甲藻门3属3种,隐藻门2属3种,金藻门2属2种。结果显示:添加Nualgi和补充硅藻藻种都可以有效提高水体中硅藻的生物量并抑制绿藻和蓝藻的生长,同时可以改变水体中浮游植物的群落结构,试验进行到第20天时,M1组、M2组和M3组中硅藻的生物量均显著高于C组,绿藻和蓝藻的生物量显著低于C组。试验中,颗粒直链藻在M1组、M2组和M3组中成为优势藻种,但并未在C组中成为优势藻种,小空星藻和四足十字藻仅在C组中成为优势藻种,四尾栅藻在M1组、M2组和C组中均成为优势藻种。在试验期内,各试验组之间的多样性指数没有显著差异,香农-威纳指数均在2.00以上,表明Nualgi和硅藻藻种并没有影响到水体中藻类的多样性。 相似文献
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Association between the interannual variation in the oceanic environment and catch rates of bigeye tuna (Thunnus obesus) in the Atlantic Ocean 
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下载免费PDF全文 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. 相似文献
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Liping Li Rui Wang Wanwen Liang Xi Gan Ting Huang Yan Huang Jian Li Yunliang Shi Honglin Luo Ming Chen 《广西水产科技》2014,(1)
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. 相似文献
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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. 相似文献
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Growth hormone (GH) and reproduction: a review 总被引：5，自引：0，他引：5
Florence Le Gac Odile Blaise Alex Fostier Pierre-Yves Le Bail Maurice Loir Brigitte Mourot Claudine Weil 《Fish physiology and biochemistry》1993,11(1-6):219-232
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. 相似文献
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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. 相似文献
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Controlled infection of Poecilia reticulata Peters (guppy) with Tetrahymena by immersion and intraperitoneal injection 下载免费PDF全文
下载免费PDF全文 G Sharon M Pimenta‐Leibowitz M C L Vilchis N Isakov D Zilberg 《Journal of fish diseases》2015,38(1):67-74
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). 相似文献
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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. 相似文献
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Sandra García‐Garrido Ismael Hachero‐Cruzado Carlos Rosas Pedro Domingues 《Aquaculture Research》2013,44(11):1741-1751
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. 相似文献
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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. 相似文献