不同饵料对魁蚶稚贝生长和存活的影响

在温度23.5～24.0 ℃和盐度29.5～30.0条件下,研究了球等鞭金藻、小球藻、牟氏角毛藻和新月菱形藻4种单细胞藻类单独及组合投喂24 d后对魁蚶稚贝生长与存活的影响.结果表明: 不同饵料投喂条件下,稚贝存活率均在95%以上,不同处理组间差异不显著.单一饵料投喂组中,球等鞭金藻组的稚贝生长最快,小球藻组的稚贝生长最慢.组合投喂组中,球等鞭金藻与其他3种单胞藻混合(1∶1)投喂组稚贝壳长及特定生长率均优于其他组,其中与小球藻混合投喂的效果最好,稚贝壳长和壳高的特定生长率分别为5.6%·d^-1和6.4 %·d^-1.研究结果可为魁蚶人工苗种培育技术的优化提供参考依据.
     

食物种类对萼花臂尾轮虫种群增长率的影响

在短期慢性观测过程中,食物类型可能是造成萼花臂尾轮虫(Brachionuscalyciflorus)种群繁殖率变化的一种原因。共观测了分别单独投喂10种不同绿藻对轮虫种群增长率的影响。为验证藻青菌是藻类饵料(如绿藻Scenedesmus)有价值的佐剂这一假说,还用蓝细菌单独投喂或与斜生栅藻(Scenedesmusobliquus)混合投喂轮虫进行实验观测。结果发现食物种类对萼花臂尾轮虫种群增长率影响显著。斜生栅藻组获得最大种群增长(1.6/d),而Desmodesmus组增长率最低(0.3/d)。以占斜生栅藻组最大增长的百分率来表示,其它几种绿藻组种群增长由高到低依次为:Desmodesmussubspicatus88%,小球藻(Chlorellavulgaris)83%,单壳缝藻(Monoraphidiumminutum)77%,D.quadricauda74%,S.falcatus71%,S.acuminatus69%,S.pectinatus64%,莱茵衣藻(Chlamydomonasreinhardtii)57%,D.abundans19%。轮虫增长率的差异不能用藻类饵料的大小差异来解释。蓝细菌(Microcystisaeruginosa)和(Synechococcuselongates)不论是单独投喂还是与优良藻类饵料(斜生栅藻)混合投喂都对萼花臂尾轮虫种群增长有抑制作用。这种副作用似乎与微囊藻素无关。该结果不支持无毒蓝细菌可作为与其他绿藻饵料配合使用的优良佐剂这一假说。本研究所观察到的生长变化显示了饵料种类对萼花臂尾轮虫种群增长的影响,也预示了对毒性实验结果的影响     

4株微藻悬浮和固定培养生长和氮磷去除效果的比较

为了比较牟氏角毛藻(Chaetoceros muelleri)、蛋白核小球藻(Chlorella pyrenoidosa)、三角褐指藻(Phaeodactylum tricornutum)、新月柱鞘藻(Nitzschia closterium)四株微藻在悬浮和固定培养方式下藻细胞生长状况和氮磷去除效果,试验采取模拟含氮磷人工污水,向培养液中添加NH₄Cl,在相同培养条件下,分别培养4株微藻。实验结果表明:4株微藻在悬浮和固定化培养均能生长,氮磷去除效果良好。4种微藻悬浮培养的生长速率要优于固定化培养。两种培养方式生长速率均为:蛋白核小球藻>新月柱鞘藻>三角褐指藻>牟氏角毛藻;4种藻在悬浮培养下,NH₄⁺-N和PO₄^3--P去除率为:新月柱鞘藻>三角褐指藻>牟氏角毛藻>蛋白核小球藻;4种藻在固定化培养下,NH₄⁺-N和PO₄^3--P去除率为:新月柱鞘藻>...     

不同饵料和饥饿对魁蚶幼虫生长和存活的影响

在水温23.2-24.0℃,盐度29.5-30.0条件下,研究了5种单胞藻饵料和饥饿对魁蚶浮游幼虫生长与存活的影响.投喂不同饵料试验中,球等鞭金藻与4种单胞藻混合投喂试验组幼虫的特定生长率、眼点幼虫比例和壳长均显著高于单一投喂试验组,其中球等鞭金藻与小球藻混合投喂的效果最好;投喂单一饵料试验中,球等鞭金藻组幼虫的生长、眼点幼虫比例与存活率显著高于其它试验组.在饥饿试验中,不同饥饿天数条件下幼虫的存活率差异不显著;生长方面,饥饿1-2d较短时间与一直投喂对照组的幼虫相比较,特定生长率、眼点幼虫比例、壳长的差异不显著,但随着饥饿时间延长,幼虫的生长变慢且眼点幼虫比例下降,一直饥饿情况下幼虫的生长基本停滞.研究结果可以为魁蚶人工苗种繁育技术的改进提供参考依据.     

温度、盐度和食物条件对西藏拟溞摄食强度的影响

报道了不同温度、盐度和饵料条件下西藏拟溞的摄食强度、西藏拟溞对不同饵料生物蛋白核小球藻(Chlorellapyrenoidesa)、牟氏角毛藻(Chaetoceros muelleri)、湛江等鞭金藻(Isochrysis zhanjiangensis)、亚心形扁藻(Platymonas subcordiformis)、盐藻(Dunaliella salina)、新月拟菱形藻(Nitzschiella closterium)的选择性以及摄食节律。结果表明,在适温范围(2 20℃)内,西藏拟溞的滤水率、摄食率随着温度的升高而增加,14 16℃为西藏拟溞的适宜温度。在盐度20时,西藏拟溞的摄食率最高,幼、成溞对等鞭金藻的摄食率分别为1.88 ng C/(ind.h)和3.46 ng C/(ind.h)。西藏拟溞对角毛藻的滤水率和摄食率均随着龄期增加而增加,而对等鞭金藻呈相反趋势,但二者的日粮均随体长增大而减小。幼、成溞的滤水率和摄食率随食物密度变化的趋势基本一致,均是在盐藻密度为1×106 ind./L时均最高,分别为0.194、0.221 mL/(ind.h)和0.030μgC/(ind.h)和0.034μgC/(ind.h)。幼溞对6种藻的食物选择性为角毛藻小球藻盐藻扁藻金藻拟菱形藻;成溞为扁藻角毛藻盐藻金藻小球藻拟菱形藻。幼溞、成溞均对角毛藻和盐藻的选择性较好。西藏拟溞的幼溞和成溞对牟氏角毛藻的摄食有相同的节律,在15:00 17:00和01:00 03:00时有两个摄食高峰,在09:00 11:00和23:00 01:00有两个低谷。     

鲢对藻类摄食效应的室内模拟研究

为研究鲢(Hypophthalmichthys molitrix)对藻类的摄食作用, 采用小环藻(Cyclotella)、小球藻(Chlorella)、微囊藻(Microcystis)和东湖原水开展了小规格鱼种的养殖试验, 对鲢摄食和排泄物进行了研究。结果显示: 在3 种纯培养藻种投喂下鲢存活率从高到低依次是小环藻组 小球藻组 微囊藻组;相应地, 鲢对藻的平均摄食率排序也是小环藻组 小球藻组 微囊藻组。在显微镜下观察粪便发现大部分小环藻为空壳, 一部分小球藻外部形态结构不完整, 外部形态完整的小球藻则色泽暗淡、内部结构紊乱, 微囊藻没有明显变化;3 种藻类细胞的受损率分别为20.04%、7.13%和1.97%。叶绿素荧光活性显示, 粪便中小环藻基本失去光合活性, 小球藻活性极显著降低(P0.01), 微囊藻活性明显降低(P0.05), 东湖原水处理组光合活性较对照极显著降低(P0.01)。对东湖水饲喂试验组排泄物的检测发现, 浮鞘丝藻Planktolyngya、鱼腥藻Anabeana(有破损)、假鱼腥藻Pseudoanabaena 和颤藻Oscillatoria 细胞受损严重;空星藻Coelastrum 和盘星藻Pediastrum 细胞部分破损;针杆藻Synedra、小环藻、桥弯藻Cymbella 和舟形藻Navicula 多为空壳。鱼粪中平裂藻Merismopedia、微囊藻、浮鞘丝藻、鱼腥藻、颤藻、卵囊藻Oocystis、栅藻Scenedesmus 和衣藻Chlamydomonas 在重新培养后恢复了生长。本研究显示硅藻尤其是小环藻、针杆藻和舟形藻对鲢摄食最敏感;栅藻、卵囊藻和平裂藻对摄食压力不敏感。研究表明鲢捕食对藻类群落结构有明显的改变效应, 利用鲢的滤食进行藻类群落调节和水华防控具有可行性。       

不同萃取体系对小球藻藻渣成分的影响

考察5种萃取体系（A：正己烷,B：正己烷/乙醇,C：正己烷/异丙醇,D：氯仿/甲醇,E：氯仿/乙醇）对小球藻（Chlorella phyrenoidosa）油脂的提取效果及藻渣成分的影响。实验结果表明：不同的萃取体系下,油脂得率为D（12.27%）、E（8.87%）、C（7.71%）、B（6.80%）、A（3.91%）,藻渣蛋白含量为A（52.60%）、E（46.23%）、B（40.19%）、C（39.52%）、D（32.52%）,藻渣碳水化合物含量为A（23.28%）、E（16.15%）、B（13.24%）、D（13.50%）、C（9.06%）;藻渣色素含量为A（1.75%）、E（1.29%）、B（1.14%）、C（0.96%）、D（0.58%）;藻渣灰分含量为D（3.63%）、E（2.94%）、C（2.23%）、B（2.25%）、A（1.48%）。综合考虑微藻生物柴油的生产及藻渣的可利用性,V（氯仿）/V（乙醇）=1是一种油脂萃取效果较好,藻渣营养成分损失较小的小球藻油脂萃取体系。     

CO_2浓度倍增对牟氏角毛藻生长和光合作用的影响

高浓度（５％)ＣＯ２对微藻光合作用特征和固碳机制的影响已有了广泛的研究,但ＣＯ２提高数倍对微藻的影响报道还不多。本文以牟氏角毛藻为材料,研究其在ＣＯ２浓度倍增条件下（７００ｕＬＬ－１）的生长和光合作用特点,以期了解ＣＯ２浓度的倍增影响微藻类的生理生化效应和机制。另外,牟氏角毛藻是常用的饵料藻种,含有丰富的多不饱和脂肪酸[１］,所以还有一定的实践意义。１ 材料与方法１．１ 材料与培养 牟氏角毛藻（ＣｈａｅｔｏｃｅｒｏｓｍｕｅｌｌｅｒｉｍｕｅｌｅｒｉＬｅｍｍ．）由中国科学院海洋研究所提供。对数生长期的藻…     

不同投喂频率下复合非粮蛋白源替代鱼粉饲料对大口黑鲈生长性能和健康的影响

为探究投喂频率对不同水平的复合非粮蛋白源替代饲料鱼粉对大口黑鲈(Micropterus salmoides)生长性能、血浆生化、肠道形态和抗氧化的影响,设计了棉籽浓缩蛋白、乙醇梭菌蛋白、黄粉虫粉和小球藻4种非粮蛋白源混合(8:5:3:4)后替代0、30%、60%和90%的鱼粉的四种等氮等脂饲料(D1、D2、D3和D4),设置3个投喂频率(1、2和4次/d)。每个处理组3个重复,每个重复50尾体重为(14.23±0.07) g的大口黑鲈幼鱼,进行为期8周的室外养殖实验。结果显示,在不同投喂频率条件下,摄食D4饲料组大口黑鲈的特定生长率(SGR)和蛋白质沉积率(PRE)显著低于D1—D3组,饲料系数(FCR)显著升高(P<0.05)。在各饲料组中,投喂1次/d组的特定生长率显著低于2和4次/d投喂组(P<0.05)。在不同投喂频率条件下,摄食D4饲料组大口黑鲈血浆胆固醇(TC)、高密度脂蛋白胆固醇(HDL-C)含量显著低于D1组,谷丙转氨酶(ALT)活性显著高于D1组(P<0.05)。在各饲料组中,投喂1次/d大口黑鲈血浆葡萄糖(Glu)含量,碱性磷酸酶(AKP)和谷草转...     

三峡库区村镇水源中典型水华藻种PAC混凝去除效果比较研究

选取三峡库区村镇水源水中5种典型水华藻种(小球藻、衣藻、小环藻、针杆藻和光甲藻)为材料。比较研究了不同剂量的聚合氯化铝(PAC)对于这些藻种细胞(叶绿素a和浊度)的去除效果,以及混凝沉淀后絮体结构、形态的差异,以筛选典型水华藻种混凝去除的适宜PAC投加量。结果显示:(1)实验所选藻种形态差异明显,针杆藻呈长线形结构,小环藻呈短圆柱形结构,小球藻、衣藻和光甲藻呈球形或椭圆形,光甲藻和针杆藻细胞相对最大。(2)光甲藻和针杆藻PAC混凝去除效果最好,小球藻和衣藻次之,小环藻相对不易取得良好的混凝去除效果;PAC混凝去除效果与藻类形态特征有关。(3)针杆藻和光甲藻容易形成大而密实的絮体,小球藻和衣藻形成的絮体相对较小,小环藻絮体形成能力最弱。(4)光甲藻和针杆藻适宜的PAC投加量范围为15～80 mg/L,小球藻为15～50 mg/L,衣藻为15～65 mg/L,小环藻为50～80 mg/L;在适宜的PAC投加范围内,各试验藻液叶绿素a和浊度的去除率分别达到81%～97%和76%～97%。研究表明,PAC混凝沉淀法可用于去除三峡库区村镇水源水中5种典型水华藻种,但各藻种的适宜投加量存在差异,适量PAC均可使各藻液中的叶绿素a和浊度有效降低。     

Integrated RNA-seq and RNAi Analysis of the Roles of the Hsp70 and SP Genes in Red-Shell Meretrix meretrix Tolerance to the Pathogen Vibrio parahaemolyticus

Marine Biotechnology - The “Wanlihong” Meretrix meretrix (WLH-M) clam is a new variety of this species that has a red shell and stronger Vibrio tolerance than ordinary M. meretrix...     

Single nucleotide polymorphisms in i-type lysozyme gene and their correlation with vibrio-resistance and growth of clam Meretrix meretrix based on the selected resistance stocks

I-type lysozyme is considered to play crucial roles in both anti-bacteria and digestion function of the bivalve, which signifies that it is related to both immunity and growth. In this study, based on the principle of case-control association analysis, using the stock materials with different vibrio-resistance profile obtained by selective breeding, single nucleotide polymorphisms (SNPs) in the DNA partial sequence of an i-type lysozyme of Meretrix meretrix (MmeLys) were discovered and examined for their association with vibrio-resistance and growth. Twenty-seven SNPs were detected and fifteen of them were genotyped in clam stocks with different resistance to Vibrio harveyi (09-C and 09-R) and to Vibrio parahaemolyticus (11-S and 11-R). Allele frequency distribution among different stocks was compared. And wet weight of clams with different genotype at each SNP locus was compared. The results indicated that SNP locus 9 was associated with V.?harveyi and V.?parahaemolyticus resistance and growth of M.?meretrix. Loci 12 and 14 were associated with both V.?parahaemolyticus-resistance and growth, and also have the potential to be related with V.?harveyi-resistance of M.?meretrix. Therefore these three SNPs especially locus 9 were the potential markers which may be involved in assisting resistance selective breeding. In addition, this study showed evidence that improvements in clam resistance to vibriosis could be achieved through selective breeding. All results provided encouragement for the continuation of the selective breeding program for vibrio-resistance gain in clam M.?meretrix and the application of polymorphisms in MmeLys to the future marker assisted selection.     

Comparison of antigenicity among haemocytes of seven bivalve species by monoclonal antibodies against haemocytes of scallop (Chlamys farreri)

In this paper, haemocyte antigenicity of seven bivalve species (scallop (Chlamys farreri), bay scallop (Argoecten irradians), oyster (Crassostrea talienwhanensis), asiatic hard clam (Meretrix meretrix), monila clam (Ruditapes philipinarum), purplish washington clam (Saxidomus purpuratus) and horny ark (Scapharca subcrenta)) were analysed using monoclonal antibodies (MAbs) 1E7, 1F12, 2C6 and 2H5 against haemocytes of C. farreri, employed methods of immuno-dotblotting (IDB), indirect immunofluorescence assay (IIFA) and western-blotting (WB). The four MAbs react with haemocytes of seven bivalve species. As the results for both IDB and IIFA, MAb 1E7 was positive with haemocytes of R. philipinarum, MAb 1F12 with haemocytes of A. irradians, M. meretrix, R. philipinarum and S. purpuratus; MAb 2C6 with haemocytes of the other five bivalve species except for S. purpuratus. MAb 2H5 was negative with haemocytes of the other six bivalve species in IDB, but was positive with haemocytes of R. philipinarum and S. purpuratus in IIFA. Further experiments by WB showed MAb 1F12 was able to recognise the protein of A. irradians haemocyte at molecular weights of 156 and 80 kDa, haemocytes of M. meretris, R. philipinarum, S. purpuratus, at 60, 30, 58 kDa, respectively. MAb 2C6 recognised haemocyte M. meretris proteins at 50 and 37 kDa, A. irradians, C. talienwhanensis, R. philipinarum, S. subcrenta at 40, 38, 38, 45 kDa, respectively. There were no protein bands reacting with MAb 1E7 and MAb 2H5. The results indicate antigenic similarities exist among haemocytes of the seven bivalve species.     

RNAi assay in primary cells: a new method for gene function analysis in marine bivalve

RNA interference (RNAi) is an effective approach for gene function analysis, which is well developed in mammal cell lines. However, RNAi has rarely been reported in marine bivalve species. To provide support on functional analysis of bivalve genes, for the first time to our knowledge, we conducted RNAi assay on primary cell of clam Meretrix meretrix in this study. Firstly we explored the method of culturing primary cells of M. meretrix to ensure the cells to live at high activity for at least 2 weeks. Ferritin gene was chosen as the target gene and RNAi assay was conducted through soaking the primary cells of M. meretrix digestive gland in medium containing dsRNA of ferritin gene. Realtime PCR, western blot and immunocytochemistry analysis were used to analyze the inhibition of gene expression after RNAi. Results showed the ferritin mRNA was significantly down-regulated by 66.11% after RNAi. Western blot result showed that the expression level of ferritin protein was also depressed post RNAi. The method developed in this study proved to be reliable and effective for RNAi assay on marine bivalve cells. It would be an efficient tool for gene function analysis in marine bivalves and more studies based on primary cells of marine bivalves can be expected.     

锌诱导金属硫蛋白在文蛤不同组织中的表达

采用体外暴露法对文蛤Meretrixmeretrix进行锌(0、1.5mg/L、3mg/L、6mg/L)染毒,研究不同染毒浓度的锌离子在不同染毒时间下,诱导金属硫蛋白(metallothionein,MT)在文蛤足、肝胰腺、鳃、外套膜组织中的表达差异。取经不同浓度的锌溶液在染毒2d及4d后的不同组织匀浆、离心后经Bio-GelP-10凝胶柱层析纯化,用TU-1810紫外可见分光光度计测定每个样品中金属硫蛋白的吸光值。实验结果显示:同一浓度锌离子染毒后,MT在文蛤4个不同组织中的表达量差异较显著,一般为足>肝胰腺>外套膜>鳃;不同染毒浓度的锌离子在不同染毒时间下诱导MT在不同组织中的表达也不同,具有一定的组织差异性和规律性。     

Glycosaminoglycans from marine clam Meretrix meretrix (Linne.) are an anticoagulant

The extracted unfractionated glycosaminoglycans (GAGs) obtained from the marine clam Meretrix meretrix were fractionated by ion-exchange (Amberlite IRA-900 and 120) chromatography. The fractionated sample activity was determined through azure-A by metachromatic activity and agarose gel electrophoresis. The active fractionated sample molecular mass was determined through gradient polyacrylamide gel electrophoresis (PAGE). The structural characterization of low-molecular-weight GAGs was analyzed by Fourier transform infrared (FT-IR) and 1H-nuclear magnetic resonance (NMR) spectroscopy. The Activated partial thromboplastin time (APTT) of fractionated heparin-like glycosminoglycan is 72 IU/mg and it has a molecular mass of 15,000 Da. The disaccharide profiles, such as uronic acid 15.31%, hexosamine 24.61%, and sulfate content 11.7%, were also determined. The results of this study suggest that the GAGs from M. meretrix could be an alternative source of heparin.     

An i-type lysozyme from the Asiatic hard clam Meretrix meretrix potentially functioning in host immunity

Lysozymes function in animal immunity. Three types of lysozyme have been identified in animal kingdom and most lysozymes identified from bivalve molluscs belong to the invertebrate (i) type. In this research, we cloned and sequenced a new i-type lysozyme, named MmeLys, from the Asiatic hard clam Meretrix meretrix. MmeLys cDNA was constituted of 552 bp, with a 441 bp open reading frame encoding a 146 amino acid polypeptide. The encoded polypeptide was predicted to have a 15 amino acid signal peptide, and a 131 amino acid mature protein with a theoretical mass of 14601.44 Da and an isoelectric point (pI) of 7.14. MmeLys amino acid sequence bore 64% identity with the Manila clam (Venerupis philippinarum) i-type lysozyme and was grouped with other veneroid i-type lysozymes in a bivalve lysozyme phylogenetic tree predicted using Neighbor-Jointing method. Recombinantly expressed MmeLys showed lysozyme activity and strong antibacterial activity against Gram positive and Gram negative bacteria. MmeLys mRNA and protein were detected to be mainly produced in hepatopancreas and gill by the methods of semi-quantitative RT-PCR and western blotting. In addition, MmeLys gene expression increased following Vibrio parahaemolyticus challenge. Results of this research indicated that MmeLys represents a new i-type lysozyme that likely functions in M. meretrix immunity.     

南通如东滩涂文蛤产地环境中石油烃污染评价

南通如东滩涂是文蛤(Meretrix meretrix)的重要产地,本研究于2010年3、5、8和11月对该地区文蛤生长环境及体内的石油烃( TPHs)含量与分布进行了调查.研究表明:表层海水中各季均出现油类轻度污染站位,其中夏秋2季的油类污染程度略高于冬春;虽然4季沉积物中油类含量均符合《海洋沉积物质量》Ⅰ类标准,但沉积物中油类含量的季节变化显著,最高值出现在夏季,这可能与该时间段内的潮流冲刷等因素导致的沉积物机械组成不同有关;文蛤体内TPHs平均含量的季节分布为春季＞夏季＞冬季＞秋季.文蛤体内TPHs含量易受沉积物和水体中油类含量的影响.     

基于线粒体COI基因序列的文蛤属（软体动物门：帘蛤科）系统发育关系

测定了4种文蛤属贝类的15个个体的COI基因序列,并从GenBank下载了短文蛤(M petechialis)的相应序列.比对后的序列长度为574bp,包括93个简约信息位点,A、T、C和G的平均含量分别为21.15%、44.71%、14.05%和20.09%.通过对序列的分析,共定义了12个单倍型:文蛤(M.meretrix)4个,斧文蛤(M.lamarckii)2个,丽文蛤(M.lusoria)3个,琴文蛤(M.lyrata)1个,短文蛤2个.以青蛤(cylina sinensis)为外群,用MP法和贝叶斯法构建系统树.结果显示,短文蛤、丽文蛤和文蛤为亲缘关系较近的物种,支持短文蛤和丽文蛤为文蛤的同物异名的观点.     

文蛤微卫星DNA的筛选及其特性分析

采用磁珠富集分离法从文蛤(Meretrix meretrix)的基因组中筛选得到49条微卫星DNA序列,其中两碱基重复有3种类型36个序列,四碱基重复有14种类型26个序列.重复次数在5～30之间的序列占75.6%,30次以上重复的序列占24.4%,最高重复次数为100.根据重复单元的排列特点,完美型、非完美型及混合型序列所占比例分别为61.2%、14.5%和24.5%.本研究中构建的文蛤微卫星文库将在文蛤种质资源评价及分子遗传学研究中发挥作用.