Identification of Perkinsus-like parasite in Manila clam, Ruditapes philippinarum using DNA molecular marker at ITS region

Genomic DNA was extracted from hypnospores of Perkinsus-like parasite of Manila clam Ruditapes philippinarum collected at the fishing grounds in Huanghai Sea coast Shicheng Island and East China Sea coast Ningbo, China. The internal transcribed spacer（ITS） in rDNA was PCR-amplified, cloned, sequenced, and compared with that of five Perkinsus species in GenBank. The fragment amplified from DNA of parasite of either Shicheng Island or Ningbo contained 649 bp, including partial ssrRNA（51 bp） and ITS（＋5.8 S） （598 bp） regions. The ITS（＋5.SS） sequences of Perkinsus-like parasite of both Shicheng Island and Ningbo were all 99% identical to those ofPerkinsis atlanticus, and were not more than 95% identical to those of other four Perkinsus species including P. marinus, P. andrewsi, P. qugwadi and P. medierraneus.The ITS （＋5.8S） sequence of Perkinsus-like parasite of Shicheng Island was 99% identical to that of Ningbo. These facts about nucleotide sequences suggested that the Perkinsus-like parasite in Manila clam, Ruditapes philippinarum collected from either the Huanghai Sea coast or the East China Sea coast was P. atlanticus, and might reflect P. atlanticus strains of distinct geographic distribution.

Impact of seawater acidification on shell property of the Manila clam Ruditapes philippinarum grown within and without sediment

Although the impact of ocean acidification on marine bivalves has been previously investigated under mainly controlled laboratory conditions,it is still unclear whether the impact of acidification on sediment-burrowing species differs between those within or without sediment.In order to fill this gap in our knowledge,we compared shell properties of the infaunal Manila clam(Ruditapes philippinarum)exposed to three pH concentrations(7.4,7.7,and 8.0),within and without sediments.In the first experiment(140 d),clams were exposed to seawater in an acidification system without sediment.A decrease in shell weight corresponding to the increase in dissolution rate was observed in the group ofpH 7.4,at which shell color disappeared or whitened.SEM observations confirmed the changes of the external shell surface.In the second experiment(170 d),sediment was placed at the bottom of each exposure chamber.The effects were found obvious in shell dissolution rate and shell color in the shell specimens exposed to overlying seawater but not found in the shell specimens exposed to sediment.Although the experimental period was longer in the second experiment,shell specimens in the first experiment were more seriously damaged than those in the second experiment under acidic seawater conditions.Our results,in relation to the defense function of the shell,show that marine bivalves in burrowing behavior are more adaptable to seawater acidification than those who do not burrow into sediment.

Manila clam Venerupis philippinarum as a biomonitor to metal pollution

The Manila clam Venerupis philippinarum is a good biomonitor/bioindicator to marine metal pollution and is frequently used in aquatic toxicology. Two dominant pedigrees (white and zebra) of clam are distributed in the Bohai Sea; however, little attention has been paid to potential biological differences between these two pedigrees. In this study, we tested the sensitivity of both pedigrees to marine metal (cadmium and zinc) pollution biomonitoring and marine environmental toxicology. Results demonstrate significant biological differences in gills of white and zebra clams based on metabolic profiles and antioxidant enzyme activities. In addition, we found that hypotaurine, malonate and homarine were relatively high in white clam gills, while alanine, arginine, glutamate, succinate, 4-aminobutyrate, taurine and betaine were high in zebra clam gills. Zebra clam gills were also more sensitive to a mixture of Cd and Zn, as shown by antioxidant enzyme activities and metabolic profiles, but white clam gills could accumulate more Zn. Therefore, we suggest that the white pedigree can be used as a biomonitor to marine Zn pollution, whereas the zebra pedigree can be used for toxicology studies on Cd and Zn mixed pollution.

Larval and Juvenile Growth Performance of Manila Clam Hybrids of Two Full-Sib Families

In order to determine whether growth performance could be improved by hybridizing full-sib families of Manila clam(Ruditapes philippinarum), crosses between two full-sib families including self and reciprocal crosses were carried out. The effects of heterosis, combining ability and interaction on the growth of shell length were estimated. The results showed that the growth of hybrid larvae was intermediate between parents on days 6 and 9. Heterosis on shell length was observed, which varied at juvenile stage. The cross of ♂A×♀B(Hp varied between 10.41% and 68.27%) displayed larger heterosis than ♂B×♀A(Hp varied between 1.89% and 32.33%) did, suggesting that ♂A×♀B was an ideal hatchery method of improving the growth performance of Manila clam. The variances of general combining ability(GCA), special combining ability(SCA) and interaction(I) were significant in shell length(P < 0.05), indicating that both additive and non-additive genetic factors were important contributors to the growth of larvae and juveniles. The GCA for shell length of ♂A×♀B was higher than that of ♂B×♀A at both larval and juvenile stages. This confirmed that the cross between ♂A and ♀B showed great growth in shell length. In summary, the growth of Manila clam seeds could be improved by hybridizing selected parents from large numbers of full-sib families.

Effect of Epinephrine on the Settlement and Metamorphosis of Manila Clam Larvae

化学动机和 DDRT-PCR (微分显示颠倒 transcriptionPCR ) 被采用在马尼拉蚌幼虫的解决和变形上调查肾上腺素(EPI ) 的效果。化学动机证明 EPI 根本在马尼拉蚌幼虫的变形上有效果到某程度集中并且在设计的所有处理。动机的最重要的结果在 10 ~ 的集中被获得(-6) 摩尔 L^(-1) 并且为 4h，用六教材对的 .DDRT-PCR 证明基因表达式模式是相当不同的 betweenEPI 处理和控制。343 个扩大乐队总共被获得，在哪个之中，(19.53%) 67 是差别出现。因此， EPI 在眼睛点的基因表示上有效果幼虫的马尼拉蚌。EPI 是为马尼拉蚌的解决和变形 inducer，这能被假设。EPI 可以在膜上由绑定导致幼虫解决和变形到受体然后改变幼虫房间的基因表示。

Growth Performance of Larval and Juvenile Manila Clam(Ruditapes philippinarum) from Divergently Selected Individuals of a Full-Sib Family

In this study, the method of divergent selection was employed to test the larval and juvenile growth performance within a full-sib family of Manila clam Ruditapes philippinarum. The 10% largest and 10% smallest clam individuals(on the basis of shell length) of a full-sib family were selected as parents for the fast and slow growing lines, respectively. The difference in shell length was significant among the three lines(fast, control, and slow) tested. The sequence of shell length were fast line > control line > slow line. The responses to selection, realized heritability, and genetic gain were 0.06%–0.81%, 0.04%–0.47% and 0.58%–18.89% in the fast direction, respectively; and were 0.14%–1.27%, 0.08%–0.73%, and 0.31%–49.03% in the slow direction, respectively. The results suggested that there was a large portion of additive genetic variance affecting the growth in the full-sib family. Selection in the fast direction within the full-sib family would greatly improve the growth of R. philippinarum.

Annual Variations of Biogenic Element Contents of Manila Clam(Ruditapes philippinarum) Bottom-Cultivated in Jiaozhou Bay, China

Manila clam(Ruditapes philippinarum) was monthly sampled from its benthic aquaculture area in Jiaozhou Bay from May 2009 to June 2010. The annual variations of major elemental composition, organic content, fatness and element ratio of Manila clam were examined. The element removal effect of clam farming in Jiaozhou Bay was analyzed based on natural mortality and clam harvest. The results indicated that the variation trend of carbon content in shell(Cshell) was similar to that in clam(Cclam). Such a variation was higher in summer and autumn than in other seasons, which ranged from 9.10 ± 0.13 to 10.38 ± 0.09 mmol g-1 and from 11.28 ± 0.29 to 12.36 ± 0.06 mmol g-1, respectively. Carbon content of flesh(Cflesh) showed an opposite variation trend to that of shell in most months, varying from 29.42 ± 0.05 to 33.64 ± 0.62 mmol g-1. Nitrogen content of shell(Nshell) and flesh(Nflesh) changed seasonally, which was relatively low in spring and summer. Nshell and Nflesh varied from 0.07 ± 0.009 to 0.14 ± 0.009 mmol g-1 and from 5.46 ± 0.12 to 7.39 ± 0.43 mmol g-1, respectively. Total nitrogen content of clam ranged from 0.50 ± 0.003 to 0.76 ± 0.10 mmol g-1 with a falling tend except for a high value in March 2010. Phosphorus content of clam(Nclam) fluctuated largely, while phosphorus content of shell(Pshell) was less varied than that of flesh(Pflesh). Pshell varied from 0.006 ± 0.001 to 0.016 ± 0.001 mmol g-1; while Pflesh fluctuated between 0.058 ± 0.017 and 0.293 ± 0.029 mmol g-1. Pclam ranged from 0.015 ± 0.002 to 0.041 ± 0.006 mmol g-1. Carbon and nitrogen content were slightly affected by shell length, width or height. Elemental contents were closely related to the reproduction cycle. The removal amounts of carbon, nitrogen and phosphorus from clam harvest and natural death in Jiaozhou Bay were 2.92×104 t, 1420 t and 145 t, respectively. The nutrient removal may aid to reduce the concentrations of nitrogen and phosphorus, the main causes of eutrophication, and to maintain the ecosystem health of Jiaozhou Bay.

First molluscan antimicrobial peptide hydramacin in Manila clam:molecular characterization and expression analysis

Objective:To investigate molecular characterization and the immune responses of Manila clam hydramacin(Rp-hdmc).Methods:cDNA sequence of hydramacin was isolated from Manila clam transcriptome database.Molecular characterization of hydramacin cDNA was performed by BLAST and SWISS-MODEL bioinformatics programs.Tissue-specific expression and transcriptional regulation after Vibrio tapetis challenge was done by quantitative real time PCR.Results:Rp-hdmc has 291 bp open reading frame(ORF),encoding 97 amino acids with a mature hydramacin consisting of 77 amino acid residues.In un-challenged clam,Rp-hdmc was constitutively expressed in all tested tissues and the highest expression level was detected in gill.After pathogenic bacteria Vibrio tapetis challenge,Rp-hdmc mRNA was up-regulated in gill and hemocytes.Conclusions:We identified hydramacin cDNA(Rp-hdmc)from mollusk Manila clam that shows the characteristic features of hydramacin sequence.It has eight cysteine residues with four disulfide linkages,three helices and two β-strands in secondary structure.Expression results after V.tapetis challenges suggest that Rp-hdmc is involved in immune response against pathogenic bacteria.

菲律宾蛤仔对沉积物-水界面营养盐交换通量的影响

营养盐在沉积物-水界面的扩散影响菲律宾蛤仔(Ruditapes philippinarum)的底播、菲律宾蛤仔和鳗草实生苗的互作,推测菲律宾蛤仔规格、丰度和活动稳定性影响营养盐的扩散。将不同丰度、规格的菲律宾蛤仔置入沉积物中,室内培养19天,并于第13、19天,研究营养盐在沉积物-水界面的交换通量。菲律宾蛤仔生物量、规格和丰度、活跃性影响营养盐在沉积物-水界面的交换通量,第13天,NO_(2)^(-)-N、NH_(3)-N、TN交换通量受菲律宾蛤仔规格影响,NO_(2)^(-)-N和NH_(3)-N交换通量随菲律宾蛤仔规格增大而增大。第13天和19天,NO_(2)^(-)-N、NH_(3)-N、TN、PO_(4)^(3-)-P交换通量受菲律宾蛤仔丰度影响,随菲律宾蛤仔丰度增大而增大。因此,评估滤食性贝类环境容量、贝类与海草的互作时,需考虑贝类生物量、规格和丰度的作用。

菲律宾蛤仔橙色品系壳形态性状对质量性状的通径及多元回归分析

以124枚菲律宾蛤仔Ruditapes philippinarum橙色品系为研究对象,测量其壳长(X1)、壳高(X2)、壳宽(X3)、活体质量(WL)和软体质量(WM),采用通径及多元回归方法对橙色品系的壳形态性状(X1、X2、X3)对质量性状(WL、WM)进行分析。结果表明:菲律宾蛤仔橙色品系蛤仔壳形态性状与活体质量及软体质量的相关性极显著(P<0.01);壳宽、壳高分别是影响活体质量的主要和次要因素,壳长、壳宽分别是影响软体质量的主要和次要因素;运用逐步回归法,将自变量的通径系数不显著项去除,以壳形态性状为自变量,活体质量为因变量,建立活体质量的最优回归方程为WL=-6.917+0.142X1+0.15X2+0.351X3。

菲律宾蛤仔(Ruditapes philippinarum)对潮间带水层-沉积物界面颗粒通量影响的研究

研究利用中型生物扰动系统 (AFS)对胶州湾薛家岛潮间带菲律宾蛤仔 (Ruditapesphilippinarum)养殖断面和非养殖断面的中潮和低潮 4个站位的生物沉降和沉积物的再悬浮过程进行测定。结果表明生物沉降作用与大型滤食性双壳类动物 -菲律宾蛤仔的丰度呈显著的正相关关系 (r=0 .984 ,P<0 .0 5 ) ,养殖断面的生物沉降作用要明显地大于非养殖断面。在菲律宾蛤仔的低密度区 ,生物沉降的作用小于自然沉降 ,而在其养殖的高密度区 ,生物沉降率约为自然沉降率的4倍。薛家岛潮间带沉积物的临界侵蚀速率为 17.4～ 2 0 .4 cm/ s。沉积物的稳定性与所测生物因子的关系不密切 (P>0 .0 5 )。作者推测两个断面中潮站位沉积物的相对易侵蚀性 。

天津沿海菲律宾蛤仔人工育苗技术的初步研究

利用自然海水和天然饵料,采用无泥砂采苗方法,在天津沿海首次成功开展了菲律宾蛤仔工厂化育苗。幼虫初始壳长93.8μm,壳长平均日增长8.3μm,成活率41.0%;第15-23 d为变态期,壳长平均日增长12.9μm,变态率47.8%;变态后至第55 d,壳长平均日增长33.2μm,成活率76.0%。本次育苗试验充分利用天津沿海水质条件与环境特点,改进育苗方法,降低生产成本,建立了适于天津海区的菲律宾蛤仔人工育苗工艺,共得到双水管稚贝约1 800万枚。

天津沿海菲律宾蛤仔适养密度研究

为查明大神堂浅海菲律宾蛤仔养殖的适宜密度和生长特征，开展了放养密度对不同养殖阶段蛤仔生长与存活的影响试验。幼贝初始规格为壳长5.6±1.3mm，养殖密度设置为8000粒/m2、4000粒/m2；成贝期，养殖密度设置为500粒/m2、1000粒/m2、2000粒/m2、4000粒/m2。经26个月的养殖，结果表明：在幼贝期，当幼贝壳长小于22mm时，两密度试验组生长速度及存活率无显著差异，当幼贝壳长大于22mm时，高密度组生长缓慢，差异显著。在成贝养成前期，各密度试验组壳长无显著差异，随着蛤仔的生长，当壳长达到30mm以上时，4000粒/m2密度组生长速度显著低于其他组，其他各组间差别不明显；4000粒/m2密度组蛤仔死亡率高于50%，其他组死亡率在15%-22%之间；另外，4000粒/m2密度下蛤仔繁殖期的肥满度显著低于其他试验组，而其他组之间无显著差异。因此，2000粒/m2为该海域蛤仔养殖的适宜密度，适于培育大规格商品贝。

菲律宾蛤仔高密度育苗技术

设计和制造了可以大规模应用于菲律宾蛤仔(Ruditapesphilippinarum)等经济贝类苗种生产的高密度幼体培育系统、高密度稚贝培养系统,并建立了与之相配套的贝类育苗新工艺。克服了传统育苗方式占地面积大、生产效率低、种苗质量和产量不稳定的弱点,具有低消耗、高质量和高效益的突出特点,是贝类育苗工艺的变革。利用这一育苗技术,可以充分发挥高密度、集约化生产的优势,通过对苗种培育过程中水质、饵料和环境条件的全面控制,消除或减少敌害生物的影响,提高幼体的抗逆能力,从而杜绝抗生素的使用;在降低育苗生产的环境污染同时,向养殖户提供健康、优质的贝类苗种,是一种与环境相协调的、可持续的水产苗种培育模式。

牡蛎、缢蛏和菲律宾蛤仔中微量元素的分析研究

采用硝酸高氯酸法消解样品,应用ICP-AES法测定了牡蛎、缢蛏和菲律宾蛤仔中Ca、Co、Cr、Cu、Fe、Mg、Mn、N、iSe、Sr、V和Zn共12种微量元素。实验结果表明,3种贝类中均含有大量的Ca、Cu、Fe、Mn、Zn、Mg,还含有Co、Cr、N i、Se、Sr和V等对人体有益的微量元素,是营养价值较高的海产品,可以作为人体补充微量元素的重要来源。

细胞松弛素B对菲律宾蛤仔三倍体诱导及早期胚胎发育的影响

采用0.25 mg/L、0.5 mg/L、0.75 mg/L、1.0 mg/L细胞松弛素B(CB)抑制第二极体(PB2)的释放诱导菲律宾蛤仔三倍体,观察三倍体蛤仔的早期胚胎发育。结果表明:CB的浓度对菲律宾蛤仔三倍体的诱导以及胚胎发育影响显著(P<0.05),0.5与0.75 mg/L CB处理组诱导率较高,分别达89.4%与89.2%;各组第一极体(PB1)同步释放,处理组PB2受到明显抑制;CB处理浓度与胚胎发育速度呈负相关,与各发育阶段的畸形率及畸形程度呈正相关。综合诱导率及早期胚胎发育状况,0.5 mg/L是CB诱导菲律宾蛤仔三倍体的适宜浓度。

菲律宾蛤仔Ruditapes philippinarum底播区沉积物中有机物的积聚通量及环境指示意义

大沽河河口潮滩菲律宾蛤仔的年产量为3.4kg/m2·a,为评价菲律宾蛤仔的底播增殖对沉积环境的影响,于2009年的2、5、8和11月,在胶州湾大沽河河口采集了长12cm的柱状沉积物,研究其有机物含量、积聚通量.结果显示,贝类的生物扰动、生物沉积和收获蛤仔的耙网的扰动导致养殖潮滩的含水率升高、沉积物干容重降低,有机物含量和有机物积聚通量增加.12cm长的沉积物中有机物含量所表现出的时空分布特征和表层沉积物(≤2cm)所反映的有机物分布特征类似,但非养殖潮滩中有机物含量沿沉积物深度的变异程度高于养殖潮滩的.该潮滩的贝类底播增殖并不存在食物限制,即养殖规模没有超出由食物供给确定的养殖容量;在当前规模下,菲律宾蛤仔的底播增殖使碳在沉积物中积聚.

高选择压力下蛤仔奶牛蛤品系两个世代连续选择的选择反应和现实遗传力

以1%为选择压力,以壳长为选择指标,对菲律宾蛤仔Ruditapes philippinarum奶牛蛤品系进行了两个世代的连续混合选择,并跟踪测量了各试验组在不同生长阶段的壳长,计算了选择反应、现实遗传力和遗传获得等遗传参数。结果表明:在奶牛蛤两个世代的各个生长阶段,选择组的平均壳长均大于对照组;F2和F3世代的选择反应在幼虫培育期、稚贝培育期和幼贝养成期的平均值分别为1.98、0.72、0.64和1.10、0.68、0.74,总平均值分别为1.19和0.90;F2和F3世代的现实遗传力在幼虫期、稚贝期和幼贝期的平均值分别为0.43、0.16、0.14和0.41、0.26、0.28,总平均值分别为0.26和0.34;F2和F3世代的遗传获得在幼虫期、稚贝期和幼贝期的平均值分别为4.79%、17.81%、13.27%和5.60%、4.28%、16.30%,总平均值分别为10.78%和7.94%;F2和F3世代的总遗传获得在幼虫期、稚贝期和幼贝期的平均值分别为10.73%、15.56%、29.34%,总平均值为16.59%。研究表明,在高选择压力下进行两个世代蛤仔连续混合选择的方法获得的选育效果较为理想,且该群体仍具有一定的改良潜力。

天津沿海天然水质条件下菲律宾蛤仔D形幼虫生长的初步研究

建立上选和普通两个实验组,研究了菲律宾蛤仔D形幼虫在天津沿海天然水质下的生长状况,经过前10 d的生长比较发现,两组的平均壳长差别显著,分别为139.0和132.9μm,第7天的幼虫存活率分别为32%和28%.

菲律宾蛤仔修复重金属-营养盐-石油烃复合污染的潜在性

为了研究重金属-营养盐-石油烃复合污染下菲律宾蛤仔(Ruditapes philippinarum)的代谢特征及其过氧化物歧化酶(SOD)活性,判断其用于复合污染生态修复的可能性。以海沙模拟菲律宾蛤仔生境,将其暴露于重金属-营养盐-石油烃复合污染,测定其耗氧率、排氨率和SOD活性。结果表明:氨氮和汞对菲律宾蛤仔耗氧有协同增益作用;氨氮促进菲律宾蛤仔氨氮排泄;SOD活性不受重金属、营养盐和石油烃的影响。考虑到菲律宾蛤仔对重金属、营养盐和石油烃的耐受性及富集特性,认为菲律宾蛤仔是修复重金属-营养盐-石油烃复合污染的潜在物种。