Effects of temperature and salinity on the development of embryos and larvae of the veined rapa whelk Rapana venosa （Valenciennes, 1846）

The major population of the veined rapa whelk Rapana venosa(Valenciennes, 1846), which is an important fishery resource, is facing a large decline in China. We studied the effects of incubation temperature(16–34℃ at salinity 30) and salinity(5–45 at 25℃) on the incubation period and subsequent larval development. In the temperature experiment, the shortest incubation period was 12 days at 34℃, the lower temperature limit was 16℃, the longest mean shell length(1 193±17 μm) occurred at 25℃ and the highest survival rate 72.28%±5.62% was observed at 28℃. In the salinity experiment, the shortest incubation period was 15 days at 25. The salinity tolerance range was 15–40, the longest mean shell length(855±9 μm) and the highest survival rate 72.93%±4.85% were both observed at 35. This study demonstrated that, during the egg–mass stage, temperature and salinity regimes infl uence later growth and survival of larvae. These observations deepen our understanding of the ecology and conservation of natural populations of Rapana venosa.     

Ultrastructure developments during spermiogenesis in Polydora ciliata (Annelida: Spionidae), a parasite of mollusca

Spionid worms of Polydora ciliata inhabit the shells of many commercially important bivalves and cause disease in molluscan aquaculture. Their sperm structure is closely related to their fertilization method. To give an insight into the sperm structure and spermatogenesis, ultrastructure details of the subcellular components of germ cells during spermiogenesis of Polydora ciliata are detected by transmission electron microscopy (TEM). In P. ciliata, during spermiogenesis, chromatin is regularly arranged as dense fibrils and becomes more condensed when the nucleus elongates. Microtubules do not surround the nucleus during its elongation. The Golgi phase is characterized by the formation of proacrosomal granules within the Golgi apparatus. The proacrosomal granules fuse to form a single, spherical acrosomal vesicle that migrates to the anterior pole of the cell. At the time of nuclear condensation, mitochondria become reduced in number but increased in size, causing deep indentation at the base of the nucleus. The mid-piece has a few mitochondria. The cap phase includes the spreading of the acrosomal granule over the surface of the nucleus of the differentiating spermatid. The acrosomal phase of spermiogenesis is typically associated with changes in the shape of the nucleus, acrosome and tail. The relationship of sperm ultrastructure to spermiogenesis in spionidae species was discussed.     

中国近海栉江珧属分类与地理分布研究进展

本文收集了涉及中国栉江珧属(Atrina Gray,1842)分类和分布的文献,结合近年来栉江珧属分子生物学的研究结果以及野外调查情况,对栉江珧属种类和地理分布情况进行了系统的梳理,确定了中国共有7种栉江珧属贝类,并对其分类分歧进行了讨论;概括各栉江珧属种类的地理分布,广东是中国近海栉江珧属物种多样性最丰富的省份,其次为广西壮族自治区。根据目前中国栉江属种类的资源现状,对栉江珧属种类的开发利用与保护提出了建议,以期为深入开展全国范围的栉江珧属生物多样性保护和可持续利用提供科学依据。     

Genetic variation within and among range-wide populations of three ecotypes of the Japanese grenadier anchovy Coilia nasus with implications to its conservation and management

Journal of Oceanology and Limnology - Studies of range-wide populations can contribute to the comprehension of the relative roles of historical events and contemporary factors that influence...