Survival, growth and immune activity of scallop Chlamys farreri cultured at different depths in Haizhou Bay (Yellow Sea, China) during hot season

Survival, growth and immune response of the scallop, Chlamys farreri, cultured in lantern nets at five different depths (2, 5, 10, 15, and 20 m below the sea surface) were studied in Haizhou Bay during the hot season (summer and autumn) of 2007. Survival and growth rates were quantified bimonthly. Immune activities in hemolymph (superoxide dismutase (SOD) and acid phosphatase (ACP)) were measured to evaluate the health of scallops at the end of the study. Environmental parameters at the five depths were also monitored during the experiment. Mortalities mainly occurred during summer. Survival of scallops suspended at 15 m (78.0%) and 20 m (86.7%) was significantly higher than at 2 m (62.9%), 5 m (60.8%) or 10 m (66.8%) at the end of the study. Mean shell height grew significantly faster at 10 m (205.0 μm/d) and 20 m (236.9 μm/d) than at 2, 5 or 15 m in summer (July 9 to September 1); however, shell growth rate at 20 m was significantly lower than at the other four depths in autumn (September 2 to November 6). In contrast to summer, scallops at 5 m grew faster (262.9 μm/d) during autumn. The growth of soft tissue at different depths showed a similar trend to the shell. Growth rates of shell height and soft tissue were faster in autumn than in summer, with the exception of shell height at 20 m. SOD activity of scallops increased with depth, and ACP activity was significantly higher at 15 and 20 m than at other depths, which suggests that scallops were healthier near the bottom. Factors explaining the depth-related mortality and growth of scallops are also discussed. We conclude that the mass mortality of scallop, C. farreri, during summer can be prevented by moving the culture area to deeper water and yield can be maximized by suspending the scallops in deep water during summer and then transferring them to shallow water in autumn.     

原位杂交结合半薄切片对石鳖贝壳发育相关细胞的观察研究

多板纲软体动物(石鳖)生有8片重复排列的贝壳,与其他类群如腹足类、双壳类等有显著的区别,这些差异蕴含着重要的发育和演化意义。前期研究发现,红条毛肤石鳖(Acanthochitona rubrolineata)幼虫贝壳发育组织的细胞排列欠规则,在普通显微镜下不易识别单个细胞结构。本研究首先利用整装原位杂交手段鉴定出一些参与贝壳发育的细胞群体,发现表达engrailed的细胞分布于贝壳发育区中央区域的突起部位(脊)和边缘区域,其中脊区域的表达呈条纹状,边缘区域的表达则与贝壳发育区的外周吻合,但是对这些细胞的形态和排列模式等细节无法开展深入观察。接下来对石鳖幼虫进行了半薄切片,发现可以识别出壳板发育区细胞及脊细胞的大致轮廓和分布模式,但分辨率仍然受限。为了进一步提升分辨能力,结合了整装原位杂交实验及半薄切片技术,对表达engrailed基因的贝壳发育相关细胞开展了观察研究。结果显示,对整装原位杂交后的幼虫进行半薄切片,组织细胞结构保持完整,细胞轮廓清晰,能够清楚区分engrailed阳性细胞。观察表明,这些细胞具有较高的核质比,总体呈V形排列,且贝壳发育区中央部位与边缘部位的engraile...     

日本蟳捕食栉孔扇贝机制的初步研究

在现场和室内条件下研究了日本蟳(Charybdis japonica)对栉孔扇贝(Chlamys farreri)的捕食机制。现场实验表明,成年日本蟳可以捕食壳高小于5.0 cm的栉孔扇贝,其捕食强度随着水温的升高而增大,而壳高大于5.9 cm的栉孔扇贝则可以免遭日本蟳的捕食;相对于栉孔扇贝,日本蟳更倾向于捕食贻贝;室内实验表明水温低于10℃时,日本蟳对大规格扇贝的捕食作用不明显。相同温度条件下,室内实验日本蟳的捕食强度要低于现场,但其温度系数(Q10)差别不大。在上述实验基础上,本文提出了提高底播栉孔扇贝成活率的方法,即选择大规格的扇贝在水温较低的秋、冬季进行底播,同时添加一部分贻贝作为牺牲诱饵以减少日本蟳对扇贝的捕食。     

文蛤(Meretrix meretrix)幼虫发育过程中细胞凋亡和Caspase 功能分析

以文蛤为研究对象,利用TUNEL技术(Terminal-deoxynucleotidyl transferase mediated dUTP Nick End Labeling)检测了文蛤各发育阶段的幼虫中细胞凋亡的部位,利用Caspase原位标记分析了有活性的Caspase在幼虫中的分布情况,用Caspase抑制剂Z-VAD-FMK处理受精后4天和5天的变态前幼虫,同时以抑制剂的有机溶剂DMSO(Dimethyl sulfoxide)作对照,根据其对幼虫变态的影响,分析Caspase在文蛤幼虫变态中的作用.细胞凋亡检测结果显示,幼虫发育过程中发生细胞凋亡的部位主要在壳顶幼虫的面盘,说明细胞凋亡可能是文蛤幼虫变态过程中面盘退化的主要机制;在担轮幼虫至壳顶幼虫中都检测到有活性的Caspase,说明整个幼虫形态变化过程中都有Caspase的参与;用Caspase特异性抑制剂处理变态前幼虫,发现处理组幼虫变态率均显著低于对照组(P<0.05),说明Caspase在变态早期和晚期都有重要作用,同时发现DMSO对幼虫变态有诱导作用,可以在生产中加以利用.     

海湾扇贝样品不同保存条件下DNA的提取及RAPD扩增比较

以海湾扇贝为材料，研究了鲜活样品以及采用冷冻保存、70％乙醇固定和10％福尔马林固定等方法保存的闭壳肌样品用于DNA提取的不同效果，并分析了不同保存条件下所提得DNA用于RAPD扩增的结果，研究表明，鲜活样品以及采肜冷冻保存和70％乙醇固定的样品可以得到很好的DNA，其质量和得率没有显著差异，利用上述DNA模板进行RAPD分析，可以获得一致性很好的扩增结果。10％福尔马林休固定样品则没有得到可用的DNA模板。采用70％乙醇固定保存海洋生物组织，是用于DNA提取及相关的分子生物学研究的快速、简易和有效的方法。     

紫扇贝与海湾扇贝种间杂交的研究

为推动中国扇贝养殖业的进一步发展,作者于2008年从秘鲁引进了紫扇贝(Argopecten purpuratus),尝试将紫扇贝与海湾扇贝(Argopecten purpuratus)进行杂交,以期培育出具有优势性状的杂交子代.利用引进的紫扇贝与海湾扇贝进行种间杂交,培育出紫扇贝(雌)×海湾扇贝(雄)杂交扇贝.实验证明紫扇贝的卵子与海湾扇贝的精子可正常受精,受精卵发育正常.杂交扇贝的生长速度在幼虫阶段和成体阶段均快于海湾扇贝.至收获时,杂交贝比海湾扇贝平均壳高、壳长和壳宽分别大27.3%,25.2%和19.3%,体质量增加107.0%,杂种优势明显.