我国五大湖日本沼虾线粒体COI基因部分片段序列比较

对我国五大湖日本沼虾100个野生个体的线粒体细胞色素氧化酶亚基I（COI）部分序列进行了测定和分析，经比对获得578bp核苷酸片段，发现49个变异位点，得到35个单倍型，包括7个共享单倍型，各群体都具有较好的单倍型多态性和核苷酸多态性，其中鄱阳湖群体遗传多样性相对最高。AMOVA分析表明，五群体间总遗传分化系数F_st＝0.31873 （P<0.05）， 群体间具有较高的遗传分化。MEGA3.1软件计算五群体的Kimura 2-paramter遗传距离，洞庭湖群体和巢湖群体之间的遗传距离最远为0.0191，巢湖群体和洪泽湖群体之间的遗传距离最近为0.0051。以同属胖掌沼虾（Macrobrachium inflatum）为外群分别构建了NJ和UPGMA系统树，结果显示洞庭湖和鄱阳湖为一族群，太湖、巢湖和洪泽湖为一族群。     

基于COI和16S rRNA基因片段鉴定厦门海域的仔稚鱼

本文基于线粒体细胞色素C氧化酶亚基I(COI)基因和16S rRNA基因片段对采集于厦门海域的仔稚鱼样品进行种类鉴定,探究其在仔稚鱼种类鉴定中的适用性。研究共获得64条COI基因序列和74条16S rRNA基因序列,通过序列比对,COI基因将仔稚鱼样品鉴定为26个种类,其中19个种类鉴定到种、6个鉴定到属、1个种类仅鉴定到科;16S rRNA基因将仔稚鱼样品鉴定为29个种类,其中23个种类鉴定到种、6个鉴定到属。COI基因的平均种内遗传距离为0.001 5,平均种间遗传距离为0.197 6,16S rRNA基因的平均种内遗传距离为0.000 3,平均种间遗传距离为0.089 2,COI和16S rRNA基因的平均种间遗传距离都为平均种内遗传距离的10倍以上,两者都可以进行有效的仔稚鱼种类鉴定。在基于COI和16S rRNA基因构建的系统进化树上,所有物种都分别单独聚为一支,同一个种类的不同个体都能聚在同一个分支,这些物种均能得到有效区分。以上结果表明,COI和16S rRNA基因均可以实现仔稚鱼的种类鉴定,两种基因结合使用可以提高仔稚鱼种类鉴定的准确性。     

基于线粒体COⅠ和Cytb基因探讨北鲍南养对皱纹盘鲍群体遗传结构的影响

为探讨近三十年来我国皱纹盘鲍养殖模式对群体遗传结构产生的影响，利用线粒体细胞色素C氧化酶亚基 (COⅠ)基因和细胞色素b (Cytb)基因分析了定殖漳州的群体、大连培育蓬莱越冬群体、荣成培育福建越冬群体及长山列岛 (砣矶岛、大钦岛、南隍城岛)皱纹盘鲍群体的遗传多样性与群体遗传结构。结果显示，在259个个体730 bp的COⅠ序列片段中检测到48个变异位点和30个单倍型，6个群体的单倍型多样性为0.586~0.897，核苷酸多样性为0.0056~0.0081。259个个体730 bp的Cytb序列片段中检测到59个变异位点和32个单倍型，6个群体的单倍型多样性为0.605~0.909，核苷酸多样性为0.0077~0.0120。基于COⅠ和Cytb基因的群体间F_st值以及AMOVA结果表明，绝大部分群体之间存在显著的遗传分化，并且遗传变异主要来源于群体内。现行的皱纹盘鲍北鲍南养模式加强了不同群体之间的基因交流，使不同遗传背景的种群二次接触，导致皱纹盘鲍6个群体均具有较高的单倍型多样性和核苷酸多样性；而各养殖群体中的不同选育条件则可能是造成显著遗传分化的重要原因。本研究对分属南北沿海的6个皱纹盘鲍群体的遗传评估将为我国皱纹盘鲍资源的合理利用以及养殖模式对遗传结构的影响提供科学依据。     

利用线粒体DNA标记分析中国东南沿海拟穴青蟹种群遗传结构

为研究我国东南沿海拟穴青蟹(Scylla paramamosain)的种群遗传结构，对10个地理种群130只拟穴青蟹的线粒体DNA（mitochondrial DNA，mtDNA）细胞色素氧化酶亚基I（COI）基因片段序列进行分析。522bp的DNA片段共发现17个变异位点，定义了21种单倍型，其中单倍型2为10个地方种群的共享单倍型，占个体总数的56.15％，而大部分单倍型为稀有单倍型，只在少数种群的个别个体中出现。10个种群的单倍型多样性水平为h=0.6738，核苷酸多样性水平为π=0.1987%，基本呈由南到北递减的趋势。10个种群的总体遗传分化程度较低（FST＝0.05左右），但是极为显著（P<0.005）。基于单倍型频率和序列遗传距离法分析的共同结果，广西北海种群与大多数种群的遗传分化显著，而海南三亚种群分别与海南红树林和广东台山种群遗传分化显著。Mantel检验显示种群间的遗传分化程度与地理距离没有显著的相关性。分子进化中性检验结果表明自然选择在分子进化过程中起了重要作用，并暗示该物种在最近经历了一个快速的种群爆发及扩张事件。     

DNA条形码在西藏水系裂腹鱼亚科鱼类鉴定中的研究

为确定DNA条形码技术在西藏水系裂腹鱼亚科(Schizothoracinae)物种鉴定中的可行性,利用西藏水系所采集260尾裂腹鱼亚科样本,测定其线粒体细胞色素C氧化酶亚基1(COI)基因片段序列,计算遗传距离,构建系统发育树,并与GenBank中相关序列进行比对。260个样本经检测均获得有效COI基因扩增片段,COI基因碱基组成偏倚明显,A+T含量为54.74%,显著高于G+C含量(45.26%)。基于Kimura双参数模型计算遗传距离,遗传距离阈值设置为0.02时,260个样本可被鉴定到种的为249尾样本,11尾由于样本量少,数据库中存在多个命名,只鉴定到属,其中与形态学鉴定一致的179尾样本,一致率为68.8%,裂腹鱼亚科裸鲤属(Gymnocypris)不能通过COI基因鉴定到种,拉萨裂腹鱼(Schizothoracinae)、异齿裂腹鱼(S.schizothorax o#x02BC;connori)、巨须裂腹鱼(S.macropogon)3个种之间的遗传距离阈值以0.02不能有效鉴别,而遗传距离阈值以0.01作为这3个种的鉴定标准,可达到有效鉴别的目的。基于邻接法构建系统发育树,裂腹鱼亚科鱼类形成一个支持率较高的单系群,Bootstrap检验支持率为99%,系统进化树聚类方式与以遗传距离值为标准的鉴定结果一致,很好地反映了水系物种间的地理和历史联系。     

中国近海习见头足类DNA条形码及其分子系统进化

应用DNA条形码通用引物扩增了11种中国近海习见头足类(Cephalopoda)共计97个个体的线粒体细胞色素C氧化酶亚基I(Cytochrome Coxidase I,COI)基因片段,与GenBank收录的19种95条头足类同源序列进行比对.结果表明,头足类COI基因存在碱基插人缺失现象,杜氏枪乌贼(Uroteuthis duvauceli)插人缺失位点数多达33个;碱基组成偏倚明显,A+T含量(66.70%)显著高子G+C(33.30%)含量.基于Kimura双参数模型计算,29个物种的种内平均遗传距离为0.0072,种间平均遗传距离(0.20-2 4)是种内遗传距离的28.11倍.针对剑尖枪乌贼(Loligo edulis,Uroteuthis edulis,Photololigo edulis)分类和命名的分歧,DNA条形码分类结果显示,该物种与枪乌贼属(Loligo)和尾枪乌贼属(Uroteuthis)的COI基因同源性较低,不支持将其划归到Lolig.或Uroteuthis.近爱尔斗蛸属(Pareledone)6个代表物种的种间遗传距离较小(0.0120-0.0385),对于此类变异程度较低的物种,DNA条形码仍可准确区分,但其种间遗传距离的阈值尚待深人探讨.系统发育树的聚类分析结果表明,COI基因在种、属水平的分类鉴定及其系统进化关系与传统方法所得结果一致性较高,分别为100%,91.67%;科、目水平的一致性略低,分别为80%和66.67%.可见,线粒体COI基因作为头足类DNA条形码在物种鉴定中适用性较高,亦适用于种属水平的系统进化分析,是形态学分类系统的必要补充和佐证.     

Cyt b和12S rRNA基因条形码在灯笼鱼科鱼类物种鉴定中的应用

灯笼鱼科鱼类种类繁多, 且同属鱼类形态学相近, 因此利用分子标记对灯笼鱼进行准确的物种鉴定具有重要价值。为探讨线粒体细胞色素 b 基因(Cyt b)和 12S rRNA 基因在灯笼鱼科物种鉴定中的适用性, 对西北太平洋采集的 56 尾灯笼鱼进行扩增, 并进行序列对比与系统发育分析。研究表明, 采集的样本包括 6 种灯笼鱼, 分别为瓦氏角灯鱼(Ceratoscopelus warmingii)、长体标灯鱼(Symbolophorus californiensis)、粗鳞灯笼鱼(Myctophum asperum)、 细泰勒灯鱼(Tarletonbeania crenularis)、日本背灯鱼(Notoscopelus japonicus)以及某背灯鱼属鱼类(Notoscopelus sp.)。 核苷酸多态性分析显示, 基于 Cyt b 基因的种内与种间遗传距离比基于 12S rRNA 基因的更大。比较灯笼鱼科 2 种基因序列的结构特征, 发现 Cyt b 基因的种间平均遗传距离是种内平均遗传距离的 25 倍, 12S rRNA 基因的种间平均遗传距离是种内平均遗传距离的 26 倍, 均符合作为 DNA 条形码的基本要求。系统进化分析显示, 每种灯笼鱼均能形成独立分支, 2 个基因均能对 6 种灯笼鱼类进行鉴别; 但在 Cyt b 基因构建的进化树中, 每种鱼类能更好与数据库中已有的序列进行聚类。综上所述, Cyt b 和 12S rRNA 作为 DNA 条形码可以有效地对灯笼鱼科鱼类物种进行鉴定, 且 Cyt b 基因在系统进化关系的研究上具有更高的适用性。     

基于线粒体COⅠ基因序列的梭鲈野生群体遗传结构

为了解梭鲈种群的遗传结构，实验利用线粒体细胞色素c氧化酶Ⅰ亚基(COⅠ)基因部分序列分析了中国6个和中亚2个群体的遗传差异，并与欧洲群体的单倍型序列进行了比较。结果在640 bp的COⅠ基因序列中检测到5个变异位点，定义了7种单倍型，发现Hap1为8个梭鲈群体的共享单倍型，且与欧洲群体的HapA相同，在中国群体所占比例(93.36%)高于中亚群体(72.58%)和欧洲群体(53.85%)；Hap2和Hap3是中国群体的特异单倍型，而Hap4~Hap7为中亚群体的特异单倍型。单倍型序列的聚类图和网络图均显示Hap1/A为梭鲈群体的原始单倍型，中国和中亚群体的特异单倍型相对于原始单倍型仅有1~2个位点的变异，属于Hap1/A的亚型，与欧洲群体的特异单倍型具有较大的差异。每个群体检测到1~4种单倍型，斋桑湖(ZS)群体单倍型最多，而中国的腾格里湖(NX)、兴凯湖(XK)和鸭绿江(YJ)群体仅有1个单倍型(Hap1)；塔什干(TS)群体的单倍型多样性(H_d)和核苷酸多样性(π)最高(H_d=0.514±0.069; π=0.000 79±0.000 11)，其次是ZS群体，而中国梭鲈群体的多样性参数较低。AMOVA分析结果显示，梭鲈群体间遗传变异占20.74%，群体间遗传分化程度较高(0.15≤F_st=0.207 36<0.25)，TS群体与ZS群体和中国群体间的遗传分化极大(F_st>0.25)，中国群体中仅黑河(HH)群体与其他群体的遗传分化较大，而中国其他5个群体间无遗传分化。基于群体间遗传距离的系统进化树显示，来自中国的6个梭鲈群体与哈萨克斯坦的ZS群体聚为一支，而乌兹别克斯坦的TS群体独立为一支。研究结果为梭鲈群体的繁殖及放流管理提供了参考。     

我国五大淡水湖日本沼虾线粒体COI基因部分片段序列比较

对我国五大淡水湖日本沼虾100个野生个体的线粒体细胞色素氧化酶亚基I(COI)部分序列进行了测定和分析,经比对获得578 bp核苷酸片段,发现49个变异位点,得到35个单倍型,包括7个共享单倍型,各群体都具有较好的单倍型多态性和核苷酸多态性,其中鄱阳湖群体遗传多样性相对最高.AMOVA分析表明,五群体间总遗传分化系数Fst=0.3187(P<0.05),群体间具有较高的遗传分化.MEGA3.1软件计算五群体的Kimura 2-paramter遗传距离,洞庭湖群体和巢湖群体之间的遗传距离最远为0.0191,巢湖群体和洪泽湖群体之间的遗传距离最近为0.0051.以同属胖掌沼虾(Macrobrachium inflatum)为外群分别构建了NJ和UPGMA系统树,结果显示洞庭湖和鄱阳湖为一族群,太湖、巢湖和洪泽湖为一族群.     

中国沿海拟穴青蟹群体遗传多样性的微卫星分析

利用17对微卫星引物对我国沿海7个拟穴青蟹野生群体(杭州湾、三门湾、闽江口、东山湾、珠江口、北部湾、清澜港)进行了遗传多样性分析。结果表明,17个位点在所有青蟹群体中均为高度多态(PIC>0.5),共检测到253个等位基因;7群体的平均等位基因数(A)为9.41～10.94,平均有效等位基因数(N_e)为5.42～6.87,平均杂合度(H)为0.511～0.563,群体遗传多样性水平较高。分子方差分析(AMOVA)结果显示,94.13%的遗传变异存在于群体内,5.87%的遗传变异存在于群体间,两两群体间F_ST值为0.035 5～0.081 7(P<0.01),表明群体间遗传分化水平中等偏低。Hardy-Weinberg平衡检测表明,7群体普遍存在杂合子缺失现象。青蟹群体间遗传距离为0.253 0～0.571 9,UPGMA聚类分析表明,杭州湾与三门湾群体首先聚在一起,再与闽江口群体、东山湾群体聚为一支;珠江口群体与清澜港群体聚为另一支;两分支最后与北部湾群体聚类在一起。     

Comparative study on the embryonic development of three mud crabs Scylla spp.

Morphological changes in the embryos, egg size and development, incubation period and morphological structures of newly hatched zoea of three mud crab Scylla species were determined. The three species exhibited similar embryonic development composed of 10 stages. The mean egg diameter of Scylla serrata was significantly larger (P<0.05) at the prehatch stage. The mean egg diameters of Scylla tranquebarica and Scylla olivacea were similar (P>0.05). The incubation period was the longest in S. serrata and the shortest in S. olivacea. There was a positive relationship between egg size and larval size, as S. serrata exhibited the largest egg size and first zoea. However, no correlation was detected between egg size at prehatch and lengths of the morphological structures of the newly hatched zoea. The three species exhibited similar lengths of cephalic structures, but S. olivacea had significantly shorter (P<0.05) abdominal structures. The duration of spawning from ablation was the shortest in S. tranquebarica and the longest in S. olivacea. The study is relevant to aquaculture and fisheries management of Scylla species.     

Size at sexual maturity and body size composition of mud crabs <Emphasis Type="Italic">Scylla</Emphasis> spp. caught in Don Sak,Bandon Bay,Gulf of Thailand

Size at sexual maturity and body size composition of mud crabs Scylla spp. were examined as the basis for settling a minimum landing size as a fishing regulation in Don Sak, Bandon Bay, Gulf of Thailand, which has suffered serious mangrove habitat degradation. Mud crabs were caught using baited traps and gill nets. Hooked metal rods were also used to lever the crabs out of their burrows inside the mangroves. Two mud crab species, S. paramamosain and S. olivacea, occur in the bay; S. paramamosain is the dominant species, accounting for 87% of the samples. The size at which 50% of the S. paramamosain females reached maturity (SM₅₀) was estimated as an external carapace width (ECW) of 112.0 mm based on the morphology of the abdomen. Allometric changes in the crushing chelae height to ECW ratio suggested that the SM₅₀ of S. paramamosain males occurred at 106.4 mm ECW. The body size composition revealed that mainly immature mud crabs were exploited in Don Sak. To maintain a sustainable fishery for mud crabs, fishing regulations—including a minimum landing size based on the SM₅₀ estimates—are essential, as is habitat restoration.     

注射中华绒螯蟹及锯缘青蟹促雄性腺提取物对中华绒螯蟹雌蟹雄性化的影响

该论文首次报道了经由促雄性腺提取物的注射而在蟹类中引起的性逆转现象。此前关于蟹类促雄性腺活性研究的报道极少，而且蟹类的雄性化均是由促雄性腺的移植所产生。本实验中将锯缘青蟹和中华绒螯蟹的促雄性腺提取物分别注射到刚刚完成性别分化的中华绒螯蟹雌性幼蟹体内，此时幼蟹处于4至5期，壳宽为5～8 mm。注射之后，幼蟹经过大约1～2次蜕皮，此时在注射锯缘青蟹以及中华绒螯蟹的促雄性腺提取物的两组实验幼蟹中均能观察到雄性化现象，而注射生理盐水的对照组实验幼蟹中未能观察到相同现象。由此本实验可以证明促雄性腺确实是蟹类的一种雄性激素，注射促雄性腺提取物能引起雌性幼蟹发生性逆转；同时根据锯缘青蟹和中华绒螯蟹的促雄性腺提取物均能引起中华绒螯蟹雌性幼蟹发生性逆转的现象推测，锯缘青蟹和中华绒螯蟹两种间可能存在促雄性腺的交叉活性；不仅如此，性逆转还能在极低的注射剂量下获得，相当于中华绒螯蟹0.14促雄性腺当量和锯缘青蟹0.06促雄性腺当量。     

Mud crab pen culture: replacement of fish feed requirement and impacts on mangrove community structure

Brackishwater pond culture has been a major factor in mangrove loss in Southeast Asia, hence, the need to develop environment‐friendly technologies such as mud crab Scylla (Portunidae) culture in mangrove pens exists. This study evaluated the effects of mud crab netpen systems in central Philippines on mangrove macroflora, and the replacement of dietary fish with low‐cost pellets. Wild or hatchery‐sourced Scylla olivacea and Scylla serrata were stocked at 0.5–0.8 m⁻² in 167–200 m² nylon netpens (2.3 cm stretched mesh) in Avicennia‐dominated mangrove habitats. The feeding treatments were: (A) Zarraga: (1) no feeding (natural productivity), (2) no feeding for 1 month+supplementary feeding, (3) fish biomass and (4) low‐cost pellets, and (B) Batan: (1) fish biomass and (2) pellets+fish biomass. Feeds were given ad libitum twice daily. Growth and survival rates of S. olivacea in Zarraga pens were not significantly different among treatments, although crabs fed fish biomass had the highest survival, body weight and production. Similarly, growth and survival of S. serrata were not significantly different between the Batan treatments. Economic analysis of the latter gave a 38.5% return on investment (ROI) and 2.6 years payback period (PP) for pellets+fish biomass treatment compared with 27.5% ROI and 3.6 years PP for fish alone. Sensitivity analysis showed an improved economic performance of the pellets+fish biomass treatment by increasing the survival rate. Evaluation of mangrove community structure showed that crab culture reduced species diversity, numbers and biomass of seedlings and saplings, but not of mangrove trees. Therefore, mud crab pen culture is recommended for mangrove sites with mature trees, but not seedlings and saplings, and low‐cost pellets can reduce dependence on fish biomass.     

基于线粒体D-loop基因的中国海三疣梭子蟹遗传多样性与遗传分化研究

为探明分布于中国四大海区的天然三疣梭子蟹群体遗传多样性与遗传分化状况,实验以大连(DL)、东营(DY)、连云港(LYG)、舟山(ZS)、湛江(ZJ)和漳州(ZZ)6个三疣梭子蟹地理群体为研究对象,采用线粒体控制区D-loop全基因序列为分子标记,对中国海三疣梭子蟹野生群体的遗传多样性及群体遗传结构进行了分析。结果发现,在用于分析的1 141 bp的D-loop全基因序列中共有185个变异位点,129个简约信息位点。60个个体中共计48个单倍型,单倍性多样性指数和核苷酸多样性指数显示中国沿海三疣梭子蟹群体具有较高的遗传多样性,而且三疣梭子蟹在过去没有出现很强的选择效应,群体大小稳定。6群体三疣梭子蟹遗传分化指数(F_ST)为0.189 7,将中国沿海三疣梭子蟹作为一个大群体来讲已产生了中度分化,群体分化时间推断为(19.68～26.05)万年。LYG分别和DY、ZJ、ZZ,以及ZJ和ZZ这4组之间无明显分化,基因流较大(N_em>5),而其他11个群组间已存在一定程度的分化。特别是ZS与其它5群体产生了高度的遗传分化,DL与其他4群体发生了中度分化。遗传距离与地理距离不存在显著的相关性,群体发生与扩散可能有更复杂的原因。     

Innate immune response and gene expression of Scylla paramamosain under Vibrio parahaemolyticus infection

An epidemic of ‘milky disease’ in the mud crab (Scylla paramamosain) generally breaks out in the fall when the crab is near maturity, resulting in large economic losses in crab farming. Vibrio parahaemolyticus has been proven to be one of the major pathogens. In this study, the mud crabs were challenged with V. parahaemolyticus, and their innate immune responses were investigated in terms of total haemocyte counts (THCs), haemocytic enzyme activities and gene expression levels during a 114‐h period. The THCs of the mud crabs decreased significantly after 42 h of exposure. The activities of the haemocytic enzymes, including acid phosphatase‐alkaline phosphatase, phenoloxidase, superoxide dismutase (SOD), peroxidase and nitric oxidase synthethase, were significantly enhanced during the challenge course. The gene expression levels also significantly increased for all tested genes (proPO, Cu/Zn‐SOD, Prx, LYS, CRU and ALF) with the exception of CAT down‐regulated expression. The results may imply that the immune responses of the mud crab could be activated by the pathogens, and the data here will provide many clues for further systematic investigation of ‘milky disease’ caused by V. parahaemolyticus and the disease prevention in mud crab S. paramamosain.     

拟穴青蟹GRP78基因的克隆与应激表达

葡萄糖调节蛋白78(glucose regulated protein 78 ku,GRP78)是热休克蛋白70家族成员之一,在调节蛋白质折叠和维持内质网稳态过程中起着分子伴 侣作用。采用RT-PCR、RACE等技术,首次从拟穴青蟹获得了GRP78的cDNA全长序列。该序列全长2 284 bp,开放阅读框(ORF)为1 962 bp,编码653个氨基酸残基。 同源分析显示,该基因编码的蛋白含有HSP70家族的签名序列,C末端为内质网蛋白滞留信号KDEL,与其他物种具有很高相似性。实时荧光定量PCR结果表明,GRP78 基因在拟穴青蟹多个组织中均有表达。第一期仔蟹在不同的温度和盐度下暴露12 h后,GRP78基因表达量随环境温度升高而增加;在高盐(30)条件下GRP78表达量 较高,进而推测拟穴青蟹GRP78参与蛋白质折叠和环境胁迫的应答。     

Impact of salinity changes on growth,oxygen consumption and expression pattern of selected candidate genes in the orange mud crab (Scylla olivacea)

Change in environmental salinity level is a major limiting factor for the aquaculture productivity because it imposes severe stress on organisms that in turn retards growth. The orange mud crab (Scylla olivacea) is an important coastal aquaculture species (farming is practised in 10‰–20‰ salinity levels) in Bangladesh. The present study was conducted to investigate the changes in growth, O₂ consumption and mRNA expression levels of five selected genes in the orange mud crab (S. olivacea) exposed to three different experimental salinity levels (0‰, 10‰ and 20‰) for three months. Crabs reared at 10‰ and 20‰, showed significantly higher (p < .05) growth performance and expression of growth regulatory genes (Actin and α‐amylase). The highest levels (p < .05) of O₂ consumption and expression of ion regulatory genes (Na⁺‐K⁺‐ATPase, V‐type H⁺‐ATPase and Diuretic Hormone) were obtained at 0‰. Moderate levels of growth and expression of selected candidate genes were observed at 10‰ treatment while the highest levels of growth and gene expression were obtained at 20‰ (control salinity). Strong interactions were observed between growth performance and expression of growth genes (R² = 0.81–0.91), and rate of O₂ consumption and expression of ion regulatory genes (R² = 0.83–0.93), implying that the selected genes are important candidates for growth and ionic balance in S. olivacea. Growth performance was found to be very low at 0‰ initially, after 30 days crabs showed better growth performance at this salinity level. It is thus inferred that orange mud crab individuals might require 3–5 days for acclimation to salinity stress but it can take at least 30 days for acclimation to regular growth. Results indicate that with proper acclimation, the orange mud crab (Scylla olivacea) can be farmed at low salinity conditions and possibly in freshwater condition.     

4种河蓝蛤线粒体COI和16S rRNA基因序列的种间遗传分析

对光滑河蓝蛤Potamocorbula laevis、黑龙江河蓝蛤P.amurensis、焦河蓝蛤P.ustulata、红肉河蓝蛤P.rubromuscula4个野生种共40个个体的线粒体COI和16SrRNA基因片段进行了扩增和测序,经过筛选和剪切,得到长度为650bp和450bp的片段。序列分析显示,序列的碱基组成中G+C含量较低,16SrRNA基因种间和种内的变异较低,COI基因片段种内和种间的变异较高。以沙海螂Mya arenaria为外群,用MEGA 4.0软件中的NJ法构建了系统进化树,通过遗传距离和系统进化树可以看出,4种河蓝蛤未能达到不同种之间显著的遗传分化。