Molecular systematics and ultrastructural characterization of a forgotten species: Chattonidium setense (Ciliophora,Heterotrichea)

In the present paper we redescribe the ciliate Chattonidium setense Villeneuve 1937 combining morphological observations (live, stained, scanning, and transmission electron microscope) with behavioral notes and molecular data. Ultrastructural analysis revealed remarkable similarities between Chattonidium and representative members of the class Heterotrichea in cortical structure and cytoplasmic organization. The most similar genus for these aspects appears to be Condylostoma. To verify this relatedness, 18S rRNA genes from Chattonidium and from one Condylostoma species were sequenced. Phylogenetic analysis indicates Chattonidium belongs to the class Heterotrichea defined according to the modern taxonomy, and confirms its relatedness with Condylostoma already hypothesized by Villeneuve-Brachon (1940). The presence of the aboral cavity complex, a unique feature never described in other ciliates, and its peculiar organization revealed by ultrastructural analysis fully justify, in our opinion, the maintenance of Chattonidium in the separate family Chattonidiidae, established by Villeneuve-Brachon in 1940.     

四种鸟类卵壳的扫描电镜观察

利用扫描电镜对白鹇(Lophura nycthemera)、鹌鹑(Coturnix coturnix)、水雉(Hydrophasianus chirurgus)和灰卷尾(Dicrurus leucophaeus)卵壳的超微结构进行观察研究.结果显示，这四种鸟类的卵壳结构与其他鸟类的基本相似，由外而内依次为表层、海绵层、锥体层、乳突、壳膜层及贯穿卵壳的气孔道等.四种鸟类两两之间在海绵层小孔数、小孔直径、内表面气孔数、乳突数以及横断面厚度都存在显著差异.海面层小孔数由高到低依次为鹌鹑、白鹇、灰卷尾、水雉；海绵层小孔直径由高到低依次为水雉、灰卷尾、鹌鹑、白鹇；内表面气孔数由高到低依次为白鹇、鹌鹑、水雉、灰卷尾；内表面乳突数由高到低依次为鹌鹑、白鹇、水雉、灰卷尾；横断面厚度由高到低依次为白鹇、鹌鹑、水雉、灰卷尾.这种结构上的差异与种的特异性及其生存环境密切相关，卵壳的结构差异是鸟类对环境的一种适应.     

圆口铜鱼早期卵母细胞发生的超微结构

用透射电镜观察了圆口铜鱼早期卵母细胞超微结构,发现:第1时相,卵原细胞呈圆形,细胞核较大,核仁1个,由纤维中心、致密纤维组分、颗粒组分组成;核内异染色质少,常染色质多;细胞质中有1~2个核仁样体,线粒体数量少,其基质电子密度低,嵴不发达.第2时相,卵母细胞体积增大,核仁数目增多,形态上出现大小区别.早期细胞质中核仁样体增多,靠近核膜,不被线粒体包围;光面内质网较多,糖原颗粒均匀分布;线粒体出现聚集现象;中期线粒体包围核仁样体.晚期核仁样体由大变小,逐渐消失,细胞膜边缘开始形成胞质突起.第3时相,早期卵母细胞的细胞质形成大量突起,且越来越明显;中期放射带开始形成,滤泡细胞出现颗粒细胞和鞘膜细胞的分化,两种细胞的超微结构有显著差异;晚期卵母细胞周围胶原纤维发达,呈束状,鞘膜细胞扁平状,卵母细胞质中有丰富的细胞器.讨论了圆口铜鱼早期卵子发生的特点,并与铜鱼的卵子发生做了比较.     

Comparative sperm ultrastructure of three species in Siniperca (Teleostei: Perciformes: Sinipercidae)

Siniperca chuatsi, Siniperca kneri, and Siniperca scherzeri are three of the most economically important sinipercid species. The ultrastructure and morphology of the mature spermatozoa of them are examined using transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The sperm consists of an acrosome-less head, a short midpiece and a long flagellum. Ultrastructurally, it has a homogeneously electron-dense nucleus in a granular pattern with nuclear lucent and a nuclear fossa excluding the centriolar complex. One to four mitochondria with lamellar cristae encircle the basal body of the flagellum in the midpiece. The cytoplasm surrounding the centrioles and the cylindric cytoplasmic channel contains glycogen granules and vesicles. Comprising the conventional 9 + 2 axoneme, vesicles and lateral fins, the sperm flagellum is inserted laterally on the nucleus, therefore the spermatozoon is asymmetrical. All of the spermatozoa of the three species are of the primitive or ect-aquasperm form and conform to the teleostean type II spermatozoa instead of the previously supposed type I. Variations in the shape of the heads, angles between the two centrioles, location of the cytoplasmic vesicles, mitochondrial number and structural characteristics of the lateral fins are notable among the three species. S. chuatsi is a sister-group of the other two species and is the most differentiated. The present study provides fresh insights to the comparative spermatology of Siniperca fishes and will be useful to the existing knowledge of the sinipercid fishes in systematic characters, biodiversity conservation and reproduction.     

连翘花粉发育的超微结构研究

经显微电镜研究连翘(Forsythia suspensa)的花粉发育具以下特点:1)花粉具半覆盖层类型的外壁.外壁的发育在四分体时期启动,此时,内质网小泡排列在四分孢子体质膜边缘,可能决定着未来花粉外壁的纹饰模型.2)花粉粒具有3条萌发沟.萌发沟在发育过程中分别有外壁突起和内壁突起形成.3)生殖细胞具有暂时的胼胝质壁,不含质体,但营养细胞中有大量造粉体分布在生殖细胞周围.4)花粉散放时为二细胞、有花粉鞘.重点讨论了花粉壁的发生和萌发沟的发育.     

水稻精细胞的超微结构

在稻成熟花粉粒中，精细胞被不连续的电子透明的周质空间所包围，纵切面上显示的精细胞显著的由细胞质延伸形成的尾状结构，主要为长圆形的细胞核所占据的一端为头部，精细胞中具有一般的细胞器，其中线粒体主要位于头部，微丝成束与细胞纵轴平行排列，观察表明，在水稻成熟花粉中具有雄性生殖单位，两个精细胞以尾部紧密连接，其中一个精细胞深入到营养细胞核中。