两种陀螺藻囊壳的微细结构和元素组成分析

利用从自然界水体中采集到的标本为材料,对2种陀螺藻的囊壳的微细结构和元素组成进行分析比较,结果表明：组成陀螺藻囊壳的主要矿质元素是硅(Si)、铁(Fe)和铝(A1),并含有少量的镁(Mg)、锌(Zn)、钙(Ca)等元素。囊壳的表面形态是不规则的,不宜作为分类依据。     

鄂西地区裸藻的新种类

本文报道的是1981年5—6月在鄂西地区(包括五峰、宜都、宜昌、当阳、兴山及神农架林区)采集到的裸藻门植物5个新种,7个新变种和3个新变型。       

PLASTID MORPHOLOGY,ULTRASTRUCTURE, AND DEVELOPMENT IN COLACIUM AND THE LORICATE EUGLENOPHYTES (EUGLENOPHYCEAE)1

Chloroplast morphology was investigated in five species of euglenophytes: Trachelomonas volvocinopsis Swirenko, Strombomonas verrucosa (Daday) Deflandre, Strombomonas costata Deflandre, Colacium mucronatum Bourrelly et Chafaud, and Colacium vesiculosum Ehrenberg. All five species share a common plastid morphotype: disk‐shaped plastids with a pyrenoid that protrudes asymmetrically toward the center of the cell and is capped by a single large grain of paramylon that conforms to the shape of the pyrenoid. Although plastids demonstrated some degree of diversity among the species studied, it was not consistent with current generic boundaries. The plastids of S. verrucosa show a developmental pattern similar to that of Euglena gracilis. The plastids divide during the early portion of the light phase after cell division, and pyrenoids are reduced or absent in dividing plastids. Developmental patterns of plastid replication also suggest that these five taxa share recent common ancestry with members of the genus Euglena subgenus Calliglena.     

ARE CYTOPLASMIC POCKETS (MTR/POCKET) PRESENT IN ALL PHOTOSYNTHETIC EUGLENOID GENERA?1

In 1985, the existence of a cytoplasmic pocket formed from the reservoir membrane in the photosynthetic euglenoid Colacium was described. A band of reinforcing microtubules (MTR) derived from the ventral flagellar root lined the pocket, and a dense fibrillar mesh was associated with the membrane. A comparison of bodonid cytostomes, colorless euglenoid cytostomes, and the reservoir pocket found in Colacium suggested that the three structures were homologous and that photosynthetic euglenoids arose from phagotrophic ancestors. MTR/pockets have since been reported in other photosynthetic euglenoids, including Euglena, Eutreptia, Eutreptiella, Cryptoglena, Tetreutreptia, and Phacus. We found MTR/pockets in three additional taxa, Lepocinclis, Trachelomonas, and Strombomonas, thereby demonstrating the presence of this complex in representatives of all the major photosynthetic genera. A comparison of the MTR/pocket complex across genera indicated a reduction in structural complexity that was consistent with recent phylogenetic schemes based on molecular characters. Three alternative hypotheses of the origin of MTR/pockets in phototrophic euglenoids are presented and discussed.     

囊裸藻属与陀螺藻属囊壳微细结构及元素组成比较

对采自自然水体中囊裸藻属(Trachelomonas)的8种和陀螺藻属(Strombomonas)的两种藻类的囊壳微细结构和元素组成进行了比较分析,并探讨了这两个属的系统演化关系.结果表明:组成囊壳的矿质元素主要是铁和硅,在陀螺藻和表面粗糙的囊裸藻中,硅的含量较高,铁的含量相对较低;在大多数囊裸藻中,尤其是表面致密、光滑的种类中,铁的含量较高,硅的含量较低,矿质元素的组成与囊壳的颜色无直接关系.建议将陀螺藻属(Strombomonas)撤消,原陀螺藻属的种作为囊裸藻属(Trachelomonas)中的一个种组(Group),它们是裸藻科中最原始的具囊壳的类群.     

囊裸藻属与陀螺藻属囊壳微细结构及元素组成比较

对采自自然水体中囊裸藻属(Trachelomonas)的8种和陀螺藻属(Strombomonas)的两种藻类的囊壳微细结构和元素组成进行了比较分析,并探讨了这两个属的系统演化关系。结果表明：组成囊壳的矿质元素主要是铁和硅,在陀螺藻和表面粗糙的囊裸藻中,硅的含量较高,铁的含量相对较低;在大多数囊裸藻中,尤其是表面致密、光滑的种类中,铁的含量较高,硅的含量较低,矿质元素的组成与囊壳的颜色无直接关系。建议将陀螺藻属(Strombomonas)撤消,原陀螺藻属的种作为囊裸藻属(Trachelomonas)中的一个种组(Group),它们是裸藻科中最原始的具囊壳的类群。     

PHYLOGENY OF PHOTOSYNTHETIC EUGLENOPHYTES BASED ON COMBINED CHLOROPLAST AND CYTOPLASMIC SSU RDNA SEQUENCE ANALYSIS1

Eighteen new 16S rDNA and 16 new 18S rDNA sequences from 24 strains, representing 23 species of photoautotrophic euglenoids, were obtained in nearly their entire length. Maximum parsimony, maximum likelihood, and Bayesian phylogenetic analyses were performed on separate data (39 sequences of 16S rDNA and 58 sequences of 18S rDNA), as well as on combined data sets (37 sequences). All methods of sequence analysis gave similar results in those cases in which the clades received substantial support. However, the combined data set produced several additional well‐supported clades, not encountered before in the analyses of green euglenoids. There are three main well‐defined clades (A, B/C/D, and G) on trees from the combined data set. Clade G diverges first, while clades A and B/C/D form sister groups. Clade A consists of Euglena species sensu stricto and is divided into three sub‐clades (A1, A2, and A3). Clade A3 (composed of E. deses and E. mutabilis) branches off first; then, two sister clades emerge: A1 (composed of E. viridis‐like species) and A2 (consisting of E. agilis and E. gracilis species). Clade B/C/D consists of the Strombomonas, Trachelomonas, Cryptoglena, Monomorphina, and Colacium genera. Clade G comprises Phacus and Lepocinclis, as well as the Discoglena species of Euglena, with Discoglena branching off first, and then Phacus and Lepocinclis emerging as sister groups.     

中国具囊壳裸藻类的新种类

本文报道了在我国首次发现的１３个具囊壳裸藻类的新种类,在它们之中隶属于囊裸藻属的有５个新变种;属于陀螺藻属的有８个新变种。