Effect of parental stock size on F1 genetic structure in the bay scallop, Argopecten irradians (Lamarck, 1819)

Three F₁ families of the bay scallop, Argopecten irradians, were produced from one, two and 10 individuals. The genetic changes in these populations, which suffered recent and different levels of bottleneck, were analysed using amplified fragment length polymorphism (AFLP) techniques. In the parental stock, a total of 330 bands were detected using seven AFLP primer pairs, and 70% of the loci were polymorphic. All F₁ groups had a significantly lower proportion of polymorphic loci when compared with the initial stock, and loss of the rare loci and reduction in heterozygosity both occurred. The progeny of the larger population (i.e., N=10) exhibited a lesser amount of genetic differentiation compared with the progeny from N=2, which showed lesser differentiation than progeny from N=1. The effective population sizes (N_e) in N=1, 2 and 10 were estimated as 1.50, 1.61 and 2.49. Based on regression analysis, we recommend that at least 340 individuals be used in hatchery populations to maintain genetic variation.     

海湾扇贝一种球形病毒的形态发生及细胞病理学观察

2001年3-5月,青岛海区养殖海湾扇贝发生外套膜"糜烂病"并导致约50%亲贝死亡,主要表现为外套膜糜烂;严重者,约2/3的外套膜溃烂呈胶水状.电镜检测发现病贝体内感染有病毒等病原微生物.本文报道了该病毒粒子的形态、发生及宿主细胞由此所产生的细胞病理学变化.成熟的病毒粒子近球形,直径150～180nm,具囊膜,在细胞核附近的溶酶体内发生和增殖.发生初期溶酶体内形成板层髓样结构,随后形成块状、泡状、絮状等多形态的病毒发生基质及具有正方形花样的蛋白质晶格结构.最后,大量的病毒粒子装配形成,填充在溶酶体内.该病毒粒子主要存在于消化盲囊上皮细胞及结缔组织细胞的胞质中.受感染的宿主细胞线粒体肿胀、嵴溶解,内质网肿胀、核糖体脱落,溶酶体数量增多,核膜膨胀、溶解等,大部分细胞器受损.     

3种扇贝遗传结构的RAPD分析

用RAPD方法对扇贝科中的虾夷扇贝、海湾扇贝和栉孔扇贝的基因组DNA的特异性遗传标记进行分析,筛选了43个随机引物,有13个引物获得了片段长度在250～2000 bp之间且重复性良好的谱带,每个引物分别获得了4～17个大小不等的片段,共获得了170个扩增片段,其中12个引物得到特异性片段58个,可以将两种或者3种扇贝区别开来。通过Popgene 3.2分析软件包统计表明,虾夷扇贝与海湾扇贝的遗传距离最大,为0.2481;栉孔扇贝与海湾扇贝的遗传距离次之,为0.2161;虾夷扇贝和栉孔扇贝遗传距离最小,其值为0.2133。根据遗传距离指数,用MEGA3统计软件中的UPGMA方法进行聚类分析,构建系统树。     

海湾扇贝自交家系的建立和自交效应

以1992年12月从加拿大引种到中国、以群体交配的方式在中国繁养了7代的海湾扇贝(Argopecten irradians)为材料，随机选取15个性腺发育成熟的个体，分为A、B、C3组，分别通过自体受精建立15个自交家系，每组设各自混群对照。结果表明，海湾扇贝自体交配家系的受精率较高，并与对照组相近；但孵化率变化较大，15个自交系的孵化率变化范围为1．35％～68．23％，平均为31．44％。自交家系F。面盘幼虫的生长速率明显低于对照组，附着变态时间也迟于对照。在15个自交家系中有14个获得成体子代，共1311个个体，但各家系间差异很大，从13个到186个不等。自交家系子代个体可以发育到性成熟并可繁殖F2，证明通过自交培育海湾扇贝家系在技术上可行。方差分析表明，除A组自交家系体重与其对照差异不显著(P≥0．05)外，其余绝大多数自交家系和对照组相比，在壳长、壳高和体重方面的差异显著(P≤0．05)或极显著(P≤0．01)。本研究还表明，海湾扇贝的自交可导致自交衰退，表现为发育迟缓和个体小型化。在面盘幼虫阶段自交衰退率为25．9％，成体阶段平均为12．7％。     

三苯基氯化锡对海湾扇贝摄食_附着和存活的影响

有机锡化合物自本世纪０年代开始应用于海洋防污涂料，它是迄今为止人为引入海洋环境中的毒性最大的物质之一，它的广泛使用曾给世界各国沿海地区带来了牡蛎养殖业损失、螺类性畸变（ｉｍｐｏｓｅｘ）等一系列的生态灾难［１－３］．近十余年来，国外关于有机锡对这些非靶海洋生物的毒性已作了不少的研究，主要集中在国外常用的三丁基氯化锡（ＴＢＴ）［４－５］。在我国，天津新港、大连湾、胶州湾以及海河河口地区也发现存在着有机锡污染，因此，我国科学家们将它作为一种典型污染物，进行了环境变化和生态效应的大量研究［６］，在有机锡…     

Breeding cycle of the northern scallop, Argopecten purpuratus (Lamarck, 1819) in southern Chile

The gametogenic cycle of the northern scallop, Argopecten purpuratus (Lamarck, 1819) was studied in southern Chile. This species has a high commercial value and is cultivated in northern Chile, the location of its natural habitats. It has recently been introduced into southern Chile where advantages such as suitable sheltered locations protected from wave action favour its mass culture. However, there are also potential disadvantages, such as lower water temperatures, which could affect reproduction. The results of the monthly variations of the gonadosomatic index and the frequency of maturity stages in specimens cultivated in Metri Bay (41° 36′S; 72° 43′W) and in those kept on the seabed in Quihua Channel (41° 50′S; 73° 05′W), suggest that the maturity and spawning period of this species extends from the end of spring through autumn. This pattern was more pronounced in Metri Bay, where levels of maturity were higher, due to higher summer water temperatures, than in Quihua Channel. Specimens at different maturity stages are found throughout the year, which seems to be associated with a rapid gonad recovery. The general pattern of the gametogenic cycle of specimens in the cultures does not differ from that recorded in the natural habitat of the species. The data available suggest that during reproduction temperature changes are more important than the relative values of the temperature. This evidence would support the possibility of mass culture of this species in southern Chile, outside its natural distribution area that extends from Corinto, Nicaragua (12°S) to Valparaíso, Chile (33°S).     

不同降盐度方式对海湾扇贝幼贝存活的影响

采用3种降盐度梯度研究海湾扇贝(Argopectenirradians)幼贝的耐盐极限及其组织学性状.幼贝壳长(3.7±0.2)cm,水温21～23℃.结果表明,盐度每天降1时,幼贝的耐盐性最强,其下限为8;盐度每天降3的耐盐性次之;变梯度降盐度(盐度19以上时每天降3,19以下每天降1),幼贝耐盐性最低.盐度胁迫下幼贝的鳃和肝脏受损伤最严重.对虾与扇贝混养池塘的适宜盐度应在10以上,降盐驯化的日变化不宜超过3,最好为1.     

利用沉淀池进行海湾扇贝贝苗中间培育技术试验

将壳高５００－７００μｍ的出库稚贝放在沉淀池和养殖海区进行中间培育的对比试验，结果：经沉淀池培育到２－３ｍｍ在下海培育至５ｍｍ商品苗的保苗率为４３％，直接下海培育至商品苗的保菌率仅为１２％，商品苗规格基本相同，本试验开辟了海湾扇贝贝苗中间培育的新途径。     

在海湾扇贝亲贝促熟培养中混养海参的研究

首次在海湾扇贝亲贝的促熟培育中，在池底放养海参，利用海参来摄食扇贝的粪便和残饵，改善亲贝蓄养水质。经42天混养试验表明：实验组比对照组性腺指数明显提高，水质得到了明显的改善，换水量降低了25％-30％，降低了生产成本，同时海参也增重了约30％，取得了比较好的效果。