The influence of diet on comparative trace metal cadmium,copper and zinc accumulation in Thais clavigera (Gastropoda: Muricidae) preying on intertidal barnacles or mussels

The influence of diet on comparative metal accumulation was investigated using a predatory muricid gastropod Thais clavigera. Individuals were fed for up to 56 days on either barnacles, i.e., Tetraclita squamosa, or mussels, i.e., Perna viridis, collected from metal-contaminated and clean sites. Barnacles and mussels have contrasting metal handling strategies and, therefore, different body concentrations, intracellular distributions and detoxification systems. Field collection of prey items that accumulated body metal concentrations over a lifetime of exposure allowed bioavailability to the predator, T. clavigera, to be assessed naturally, which may not be the case for prey exposed to metals for a short time in the laboratory. T. clavigera that was fed cadmium- and copper-contaminated barnacles or mussels ingested significantly greater amounts compared to those fed conspecifics collected from clean locations. T. clavigera body cadmium and copper concentrations were not, however, significantly different between individuals fed either contaminated or clean prey. Amount of zinc ingested was similar in mussels collected from clean and contaminated environments but much less when compared to the barnacle prey. The body concentrations of zinc in T. clavigera fed mussels collected from both sites fell. In contrast, the amount of zinc ingested from barnacle prey was significantly greater from those collected from the metal-contaminated site as compared to the clean one. This was reflected as significantly greater body zinc concentrations in T. clavigera fed contaminated barnacles compared to those fed clean individuals. Copper and zinc accumulation from prey was, therefore, complex. It varied between metal and between prey type, but appeared to be related to the amount ingested and the metal handling strategy of the prey.     

Seasonal changes in imposex and tissue burden of butyltin compounds in Thais clavigera populations along the coastal area of Mirs Bay, China

We assessed the current status of tributyltin (TBT) contamination of Thais clavigera (Gastropoda) along the coastal area of Mirs Bay, China for the first time. The snail samples were collected from 10 different sites in the summer (June) and winter (December) of 2006, respectively. They were analyzed for imposex status, i.e. relative penis size index (RPSI) and vas deferens sequence index (VDSI), followed by quantification of butyltins in their tissues. Most of the collected females suffered from imposex, but the level of butyltin contamination varied with the distance from Yantian Port, which is currently the fourth busiest container port in the world. The tissue concentration of TBT varied with season. For a particular site, the winter samples in general contained much higher concentration of TBT than the summer samples. RPSI, VDSI and organotin concentrations were higher in T. clavigera collected from sites closer to the Port, such as the Seafood Street and Kat O. Both RPSI and VDSI were positively correlated with the tissue burden of tributyltin. VDSI exhibited little seasonal variability, whereas RPSI showed marked seasonal variability, with lower values in the summer samples. The current results will serve as an important reference for long-term monitoring of butyltin contamination in this area.     

Seasonal variation in imposex intensity of Thais clavigera

Imposex, specifically caused by TBT pollution, refers to the superimposition of male sexual characteristics in gastropod females. Seasonal variation of imposex intensity in Thais clavigera from both slightly and severely contaminated sites in Hong Kong waters was studied from 1988 to 1999. The male penis length showed significant difference between both sites and seasons. It was shortest during late autumn and early winter (October to December) and longest during spring and early summer (February to June). Female penis length also showed significant difference between sites. It did not change seasonally, however. The RPS (Relative Penis Size) index was the highest during autumn and early winter, and the lowest during spring and early summer. The VDS (Vas Deferens Sequence) index remained stable throughout the sampling period. This study showed that VDS index is a better indicator when we compare relative intensity of imposex. The comparison can only be meaningful provided the samples from different locations are taken during the same season.     

海产腹足类性畸变现象的形态特征

本文选取我国东南沿海的重要港口海口、北海、湛江、汕头和厦门港等作为海产腹足类性畸变现象的现场调查区，结果发现有11种海产腹足类存在性畸变。文中对分布广泛、易采集、性畸变现象普遍的疣荔枝螺的性畸变特征的解剖观察结果进行了详细的描述，同时对其他几种海产腹足类性畸变特性作了对比。根据研究结果将疣荔枝螺性畸变雌体的阴茎和输精管的畸变程度划分为5个阶段。     

疣荔枝螺(Thais clavigera)性畸变现象的解剖学和组织学研究

以解剖学和组织学的方法研究了有机锡污染生物指示种——疣荔枝螺的正常雄、雌和性畸变个体的生殖系统。结果表明，性畸变个体除具有正常的雌性器官外，还有输精管或阴茎。当性畸变程度严重时，性畸变不育个体的卵囊腺组织出现破损，并具有不规则块状的不育卵囊和未排出的正常卵囊。虽然性畸变个体的雄性器官具有表现出雄性功能的潜能，但由于缺少精巢或完整的前列腺，不可能发展成为具有雄性功能的个体，这与性逆转有着本质上的区别。有机锡污染引起的性畸变已对疣荔枝螺种群生存构成了潜在的威胁，深化此类负面生态效应的研究是人类面临的重要课题。     

疣荔枝螺形态性状对质量性状的影响

随机抽取100只同龄疣荔枝螺(Thais clavigera Kuster),开展其形态性状与体质量和软体部质量的相关与通径分析。实验选取并测量了壳长(X1)、壳宽(X2)、壳厚(X3)、壳口长(X4)和壳口宽(X5)等5项形态性状以及体质量(Y)和软体部质量(Z)等2项质量性状,运用相关分析、通径分析和多元回归分析等方法分析了各形态性状对体质量和软体部质量的影响。相关分析表明,疣荔枝螺各项性状间的相关均呈极显著(P<0.01)。通径分析表明,形态性状对体质量直接影响大小的顺序为壳长(0.459)>壳宽(0.277)>壳厚(0.209)>壳口宽(0.140);壳长对体质量的直接决定系数最大(0.220),是影响体质量的主要因素。通过多元回归分析,建立了形态性状对体质量的回归方程:Y=-9.714+0.220X1+0.204X2+0.195X3+0.151X5。     

舟山东极岛潮间带两种荔枝螺的营养成分分析

对舟山东极岛潮间带野生黄口荔枝螺Thaisluteostoma Holten和疣荔枝螺T.clavigeraKuster软体部的主要营养成分进行了分析,结果表明,两种螺的蛋白质质量分别占各自湿质量的(20.24±0.016)%和(19.16±0.004)%,粗脂肪质量分别占各自湿质量的(1.28±0.03)%和(0.86±0.010)%,糖分质量分别占各自湿质量的(2.11±0.005)%和(1.93±0.003)%;在两种螺的蛋白质中均检测出17种氨基酸,每100 g软体部干品的氨基酸质量疣荔枝螺为68.14 g、黄口荔枝螺为60.17 g;必需氨基酸质量分数与总氨基酸质量分数的比值疣荔枝螺为37.48%,黄口荔枝螺为35.57%;必需氨基酸质量分数与非必需氨基酸质量分数的比值疣荔枝螺和黄口荔枝螺分别为56.28%和55.20%,其必需氨基酸模式基本接近FAO/WHO的优良蛋白质理想模式;在粗脂肪中各检测出14种脂肪酸,不饱和脂肪酸占脂肪酸比例高;软体部中的重金属含量均在安全范围内。由此可见,两种螺均具有较高的营养价值和保健价值。     

The Mollusc Thais haemastoma -An Exhibitor of 'Imposex' and Potential Biological Indicator of Tributyltin Pollution

Abstract. In the Azores the gastropod Thais haemastoma shows varying degrees of imposex, the induction of male sex characters in the female. It is inferred that imposex in T. haemastoma is caused by tributyltin (TBT) associated with boats using organotin-based antifouling paints. The two indices - relative penis size and vas deferens sequence - employed previously for Nucella lapillus , were used without alteration. T. haemastoma is only the third species reported as exhibiting 'effective sterilisation' of the female. Unlike Nucella lapillus, T. haemastoma has a planktonic larva, allowing populations to be sustained even when local TBT pollution is high. This makes T. haemastoma potentially a better indicator species, as monitored populations can be maintained by the influx of larvae. T. haemastoma may thus provide a cheap method of assessing the extent of TBT contamination in warm waters, particularly in the Mediterranean and Atlantic Islands. Preliminary examination of material from a marina in Spain showed a high incidence of 'sterile' animals.     

疣荔枝螺(Thais clavigera Kuster)人工繁育技术研究

本实验开展了疣荔枝螺（Thais clavigera Kuster）室内全人工繁育技术研究;具体包括亲螺人工促熟蓄养、卵囊采集、孵化、幼虫培育、变态和采苗等技术研究,同时,还开展了后期面盘幼虫对不同附着基的喜好选择性实验,以及不同饵料和光照对幼虫附着的影响研究。研究表明：雌螺分批产卵,单个雌螺平均每次产出受精卵为61 750粒;在水温27~29℃时,面盘幼虫经过20 d左右的生长发育,壳长达到约600 μm,此时开始附着变态,由浮游生活转变为底栖生活;附着后10 d左右变态为稚螺。后期面盘幼虫对附着基的选择性实验表明,固着牡蛎苗的栉孔扇贝壳和附有底栖硅藻的波纹板,是稚螺理想的附着基。不同饵料和光照对幼虫附着影响实验结果表明：在附着变态期间,自然光照有利于幼虫附着变态;同时,连续投喂糠虾肉糜可显著提高幼虫变态率和稚螺成活率。本研究结果为今后疣荔枝螺产业化繁育提供了重要的理论和技术支持。     

黄口荔枝螺转录组数据的微卫星标记开发与分析

以黄口荔枝螺转录组测序所得到的拼接序列为基础,利用MISA软件进行微卫星分析,利用Primer5.0设计引物160对。结果显示,83对引物能够成功扩增,引物在黄口荔枝螺渔山列岛群体多态性检测中发现,37个SSR位点能够表现出多态性,一共获得了129个等位基因,各位点等位基因数为2~5个,平均每个位点等位基因数为3.49个,观测杂合度H_o,期望杂合度H_e,多态信息含量PIC范围分别介于0.000~0.800、0.146~0.645、0.139~0.573之间,有9个表现为高度多态,20个表现为中度多态,8个表现为低度多态。实验结果进行Hardy-Weinberg平衡检测后,利用Bonferroni correction法进行校正,有29个位点显著偏离,结果表明渔山列岛黄口荔枝螺群体总体遗传多样性水平较低。