PHYLOGENY OF THE BATRACHOSPERMALES (RHODOPHYTA) INFERRED FROM rbcL AND 18S RIBOSOMAL DNA GENE SEQUENCES

The sequence data from the large subunit of ribulose-1,5-bisphosphate carboxylase/oxygenase ( rbc L) gene and 18S ribosomal DNA (small subunit) of taxa in the freshwater rhodophyte order Batrachospermales were used to construct phylogenetic hypotheses. Taxa examined in this study represent four families, eight genera, and six sections of the genus Batrachospermum . In addition, Rhododraparnaldia oregonica Sheath, Whittick et Cole, was included in the analysis because it shares particular ultrastructural, reproductive, and morphological characteristics with members of the Batrachospermales and Acrochaetiales. The trees generated from each gene, as well as a combined data set, were largely congruent. Rhododraparnaldia consistently occurs on an early branch within the Acrochaetiales – Palmariales clade and does not appear to be a member of the Batrachospermales. In addition, Thorea violacea Bory de St. Vincent was not closely related to the other taxa of the Batrachospermales in all trees and hence the family Thoreaceae does not appear to be a natural grouping within this order. All other taxa analyzed, which are presently classified within this order, formed a monophyletic clade in most analyses. Psilosiphon scoparium Entwisle was not closely allied with the taxa of the Lemaneaceae, lending support to the newly proposed family Psilosiphonaceae. Sequence data from the remaining taxa of the Lemaneaceae support the concept of a derived monophyletic clade. The genus Batrachospermum appears to comprise many morphologically similar but distantly related taxa, which will need further investigation to resolve their taxonomic status. Tuomeya, Sirodotia and Nothocladus are retained at the generic level until further data are obtained.     

NUCLEOTIDE SEQUENCES OF THE SMALL-SUBUNIT RIBOSOMAL RNA GENES FROM SELECTED LAMINARIALES (PHAEOPHYTA): IMPLICATIONS FOR KELP EVOLUTION1

The entire small-subunit (SSU) ribosomal ribonucleic acid sequence was inferred for kelp representing seven genera: Alaria marginata Postels and Ruprecht (1824 bp), Egregia menziesii (Turner) Areschoug (1825 bp), Lessoniopsis littoralis (Tilden) Reinke (1825 bp), Macrocystis integrifolia Bory (1825 bp), Nereocystis leutkeana (Mertens) Postels and Ruprecht (1824 bp), Postelsia palmaeformis Ruprecht (1826 bp), and Pterygophora californica Ruprecht (1825 bp). We obtained a partial sequence for Eisenia arborea Areschoug (1669 bp) from a single clone of polymerase chain reaction-amplified product. The SSU sequence was too conserved among these morphologically distinct taxa to permit phylogenetic analysis. The divergence between the most distant taxa was only 0.66%. This value was used in a SSU molecular clock to suggest that the most distantly related kelp investigated in this study diverged between 16 and 30 (more probably 16 and 20) million years ago.     

PHYLOGENY OF THE SUBFAMILY SCOTIELLOCYSTOIDEAE (CHLOROPHYCEAE, CHLOROPHYTA) AND RELATED TAXA INFERRED FROM 18S RIBOSOMAL RNA GENE SEQUENCE DATA

Nuclear-encoded small subunit ribosomal RNA gene (18SrDNA) sequences were determined for Coelastrella multistriata (Trenkwalder) Kalina et Punčochářová, two species of Scotiellopsis ( S. oocystiformis (Lund) Kalina et Punčochářová and S. terrestris (Reisigl) Kalina et Punčochářová) and two species of Muriella ( M. aurantiaca Vischer and M. terrestris Boye- Petersen). Coelastrella and Scotiellopsis are members of the subfamily Scotiellocystoideae, and Muriella is a member of the subfamily Chlorelloideae in the family Chlorellaceae. Phylogenetic trees were constructed based on these sequence data and on previously known 18SrDNA sequences of 25 taxa. Coelastrella and Scotiellopsis were closely related to each other and formed a cluster with Scenedesmus vacuolatus (Shihira et Krauss) Kessler et al. This cluster shared a monophyletic ancestry with other Scenedesmus species. Muriella aurantiaca formed a sister relationship with the monophyletic lineage of Scenedesmus. However, another species, M. terrestris, was placed in the Trebouxiophyceae and was strongly related to Chlorella. The genus Mychonastes belonging to the Scotiellocystoideae was also not monophyletic. This study suggests that the subfamily Scotiellocystoideae should be removed from the Chlorellaceae.     

苔藓动物18S rRNA基因的分子系统发生初探

本文对我国沿海较为常见的8种唇口目苔藓动物的18SrRNA基因进行了PCR扩增和序列测定。结合已知的其它苔藓动物（包括内肛动物和外肛动物）以及腕足动物和帚虫的相应序列,运用分子系统学方法,研究苔藓动物门的系统发生关系,结果表明,外肛动物和内肛动物构成苔藓动物分子系统树中的二大平行支;本文测定的大室膜孔苔虫与Giribet等测定的膜孔苔虫在系统树中的位置间隔较远。结果也支持外肛动物包含被唇纲和裸唇纲两大类群的形态划分,而关于裸唇纲特别是唇口目内部的系统发生关系。分子数据的分析结果和形态分类之间的分歧有待于进一步研究。     

中华鳖太湖养殖种群和日本引进种群线粒体DNA Cyt b基因片段序列分析及分子进化初探

对中华鳖太湖养殖种群和日本引进种群共38个个体的线粒体DNA细胞色素b基因中间部分序列进行测定,比较其同源性,计算碱基组成,并用乌龟为外群构建不同单倍型的UPGMA和NJ分子系统树.在获得的408bp的序列中,A T约占58.8%,其中15个核苷酸位点存在变异(约占3.7%).两种群共有6种单倍型(haplotype),其中太湖养殖种群有4种单倍型,日本引进种群有2种单倍型.由系统树显示,中华鳖太湖种群的4种单倍型聚合成一大支,日本引进种群的2种单倍型以很高的置信度(99%)聚成一支.两种群序列上的差异,可以成为种群鉴别的分子标记.     

THE RIBOSOMAL RNA OF HAMSTER-MOUSE HYBRID CELLS

The ribosomal RNA (rRNA) of a series of hamster-mouse somatic cell hybrids was studied. Mouse 28S rRNA was separated from its hamster counterpart by a two-step procedure involving sucrose gradient centrifugation of ribosomes and polyacrylamide gel electrophoresis of rRNA. Both hamster and mouse types of rRNA were synthesized in the 11 hybrids tested, including hybrids containing only about one-half the haploid number of either mouse or hamster chromosomes. It appears that, for both hamster and mouse rRNA, when the chromosomes of one species constituted the majority of the chromosomes of a hybrid, a disproportionately higher percentage of rRNA of that species was present in the hybrid. Some hybrid clones, having a majority of mouse chromosomes, had a mouse rRNA cell concentration approximately four to five times higher than the concentration expected from linear extrapolation of the value found for the mouse parental cell line.     

PHYLOGENY OF THE ULVOPHYCEAE (CHLOROPHYTA): CLADISTIC ANALYSIS OF NUCLEAR-ENCODED rRNA SEQUENCE DATA1

Cladistic analysis of nuclear-encoded rRNA sequence data provided us with the basis for some new hypotheses of relationships within the green algal class Ulvophyceae. The orders Ulotrichales and Ulvales are separated from the clade formed by the remaining orders of siphonous and siphonocladous Ulvophyceae (Caulerpales, Siphonocladales /Cladophorales [S/C] complex, and the Dasycladales), by the Chlorophyceae and Pleurastrophyceae. Our results suggest that the Ulvophyceae is not a monophyletic group. Examination of inter- and intra-ordinal relationships within the siphonous and siphonocladous ulvophycean algae revealed that Cladophora, Chaetomorpha, Anadyomene, Microdictyon, Cladophoropsis and Dictyosphaeria form a clade. Thus the hypothesis, based on ultrastructural features, that the Siphonocladales and Cladophorales are closely related is supported. Also, the Caulerpales is a monophyletic group with two lineages; Caulerpa, Halimeda, and Udotea comprise one, and Bryopsis and Codium comprise the other. The Dasycladales (Cymopolia and Batophora) also forms a clade, but this clade is not inferred to be the sister group to the S/C complex as has been proposed. Instead, it is either the sister taxon to the Caulerpales or basal to the Caulerpales and S/C clade The Trentepohliales is also included at the base of the siphonous and siphonocladous ulvophycean clade. The Pleurastrophyceae, which, like the Ulvophyceae, posses a counter-clockwise arrangement of flagellar basal bodies, are more closely related to the Chlorophyceae than to the Ulvophyceae based on rRNA sequences. Thus, the arrangement of basal bodies does not diagnose a monophyletic group. Previously reported hypotheses of phylogenetic relationships of ulvophycean algae were tested. In each case, additional evolutionary steps were required to obtain the proposed relationships. Relationships of ulvophycean algae to other classes of green algae are discussed.     

THE PHYLOGENY OF CAULERPA BASED ON RDNA INTERNAL TRANSCRIBED SPACER SEQUENCES

Phylogenetic hypotheses for the pantropical marine green algal genus, Caulerpa , were inferred based on analyses of nuclear-encoded rDNA internal transcribed spacer (ITS) sequences. Results of these analyses were used to assess the correspondence between rDNA phylogeny and traditional sectional taxonomy, to identify synapomorphic morphological characters (including assimilator morphology and chloroplast ultrastructure), and to examine marine biogeographic hypotheses for the genus. Ribosomal DNA ITS sequences were aligned for thirty-three species and intraspecific taxa of Caulerpa. Results indicate limited correspondence between phylogeny and sectional taxonomy for the genus, (e.g., the sections Filicoideae and Sedoideae were not monophyletic). In contrast, chloroplast morphology could be mapped to the tree topology with limited homoplasy. Pantropical isolates of the filicoidean species, Caulerpa sertularioides and Caulerpa mexicana each formed monophyletic groups. Caulerpa reyesii was included as a derived taxon within the Caulerpa taxifolia clade, suggesting that these species were conspecific and affirmed the lack of correspondence between phylogeny and assimilator morphology. Isolates and various intraspecific taxa of Caulerpa racemosa did not form a monophyletic group. Instead, these taxa formed a heterogeneous assemblage with other sedoidean and filicoidean taxa. Within the C. sertularioides clade, Caribbean and Atlantic isolates formed a basal paraphyletic group, whereas eastern and western Pacific isolates formed a more derived monophyletic group. Therefore, these results are not consistent with an Indo-West Pacific origin of this species.     

中国蚌科线粒体16S rRNA序列变异及系统发育

首次测定了中国淡水贝类———蚌科 (Unionidae) 1 3个属代表种类的线粒体 1 6SrRNA部分序列。用Clustal X排序软件进行 1 6SrRNA序列的对位排列 ,序列总长度为 30 5— 32 0bp。通过Mega 2 0软件对所得线粒体 1 6SrRNA片段序列进行比较 ,共发现 1 0 8个碱基存在变异 ,其中包括 77个简约信息位点 ,并用“Pairwisedistance”计算了各属间的相对遗传距离。以贻贝为外类群 ,采用Mega 2 0软件中的“Neighbore Joining”法得到惟一一个分子系统树 ,系统树各分支的置信度由“Bootstrap”1 0 0 0循环检验。结果表明 :分布于中国的蚌科形成三个明显的类群 ,第一个类群 ,包括帆蚌属、蛏蚌属、丽蚌属和尖锄蚌属 ;第二个类群 ,由矛蚌属、扭蚌属、裂脊蚌属、鳞皮蚌属、尖嵴蚌属、楔蚌属和珠蚌属组成 ;第三个类群只包括无齿蚌和冠蚌两个属。由此可以看出 ,它们有可能分别隶属于三个不同的亚科 ,即小方蚌亚科 (帆蚌属、蛏蚌属、丽蚌属和尖锄蚌属 )、无齿蚌亚科 (无齿蚌属和冠蚌属 )和珠蚌亚科 (矛蚌属、扭蚌属、裂脊蚌属、鳞皮蚌属、尖嵴蚌属、楔蚌属和珠蚌属 ) ,由此证明小方蚌亚科在中国的存在 ,并且 ,对几个属的分类位置作了调整。其中鳞皮蚌属和蛏蚌属原来属于无齿蚌亚科 ,根据线粒体 1 6SrRNA的结果 ,前者应该放     

韩国赫坎按蚊复合体3成员种核糖体DNA内转录间隔2区的比较(英文)

本文对韩国中华按蚊、雷氏按蚊和八代按蚊核糖体DNA (rDNA)内转录间隔 2区 (ITS2 )序列进行了比较研究。用PCR扩增的rDNA ITS2片段直接测序 ,每种蚊测定 3个个体 ,结果显示 :韩国中华按蚊、雷氏按蚊和八代按蚊的rDNA ITS2序列长度分别为 4 6 8bp、 4 51bp和 4 53bp ,GC含量分别为 4 4 .87%、 4 6 .2 %和 4 5.7% ,3种按蚊序列差异范围为 12 .16 %— 30 .74 %。研究表明 ,rDNA ITS2序列差异可用于韩国中华按蚊、雷氏按蚊和八代按蚊的分子鉴别。     

MOLECULAR PHYLOGENY AND THE GEOGRAPHIC ORIGIN OF HALIOTIDAE TRACED BY HAEMOCYANIN SEQUENCES

Phylogenetic relationships of 12 species of the vetigastropodfamily Haliotidae were analysed on the basis of partial haemocyanincoding genes. Both protein-coding and genomic sequence data,of which the latter includes one ancient intron, were analysed.We were able to distinguish two genetically different monophyleticgroups with high bootstrap support: (i) the abalones from Europe,South Africa, Australia, Taiwan and Japan group together andare separated from (ii) five California and two Japanese abalones.The usefulness of haemocyanin as a phylogenetic character andthe origin of the Haliotidae are discussed. (Received 4 March 2005; accepted 4 July 2005)     

PHYLOGENY OF AUREOCOCCUS ANOPHAGEFFERENS AND A MORPHOLOGICALLY SIMILAR BLOOM-FORMING ALGA FROM TEXAS AS DETERMINED BY 18S RIBOSOMAL RNA SEQUENCE ANALYSIS1

The 18S ribosomal RNA genes from isolates of the east coast “brown tide” alga Aureococcus anophagefferens (strain Pt-1) and the Texas “brown tide” alga (strain TBA-2) were sequenced and compared to the gene sequences of Pelagomonas calceolata, a member of the Pelagophyceae, and 10 other organisms. The genes of A. anophagefferens and strain TBA-2 consisted of 1814 and 2236 bases, respectively. The difference in length was largely due to a 423-base insert occurring in the gene of strain TBA-2. Excluding the insert, 93% of the bases of the aligned sequences were identical. Phylogenetic analyses were performed based on two different alignment refinement methods (eye refinement and Gatesy refinement). Trees inferred from the Jukes-Cantor distance matrices using the neighbor-joining method were similar for both alignment methods. In both trees, A. anophagefferens, strain TBA-2, and P. calceolata formed a monophyletic group with A. anophagefferens and P. calceolata being sister taxa and strain TBA-2 occurring on a deeper-rooted branch. Bootstrap data sets for both alignment methods gave strong support for the Pelagophyceae group and the branches within that group. Parsimony analyses using the two alignments gave one tree for the eye-refined alignment and two trees for the Gatesy method. All three trees had nearly the same topology as the trees inferred from the distance method. In addition, the Pelagophyceae group and the branches within that group were supported by bootstrap analyses and decay indices. Based on the available data, A. anophagefferens and strain TBA-2 should be placed in the Pelagophyceae but not in the same order and family as P. calceolata.     

NUCLEAR RIBOSOMAL DNA PHYLOGENY OF HALIMEDALES REVEALS SEVERAL POLYPHYLETIC GENERA

Halimedales (Chlorophyta) are widely distributed in reefs and lagoons throughout the tropics and subtropics. One genus, Chlorodesmis, consists of simple, branching siphons that persist into the mature sexual phase. In most other genera, only the juvenile stages exhibit such simple anatomy. Their mature, often‐calcified thalli possess complex siphonal anatomy and differentiation depending on the location in the thallus. We obtained a nuclear ribosomal DNA phylogeny encompassing many genera in order to unravel the evolution of this complexity. Results pinpoint Caulerpa as outgroup to a clade with all other genera included in this study. The first dichotomy separates Halimeda from the remaining genera. Distinct gametangial anatomy defines these two principal clades. Within the remainder, Tydemania and its sister Flabellia are nearest neighbors to a clade containing Rhipocephalus, Udotea, Penicillus and Chlorodesmis. The latter three genera are polyphyletic. Therefore, character states of thallus superstructure defining these genera appear to be homoplasies. Chlorodesmis represents a case of neoteny where the juvenile stage persists into reproductive maturity. We will evaluate which morphological characters do change state in agreement with the molecular phylogeny and can, therefore, serve as diagnostic characters for a more natural classification.     

乌鳢肝5S rRNA的核苷酸序列

应用Peattie,Maxum等化学裂解法,辅以酶解直读法等测定了乌醴(Ophiocephalus argus)肝5S rRNA的核苷酸序列;与已知的虹鳟鱼和纵带泥鳅5S rRNA序列比较,发现它们之间的核苷酸序列具有高度的保守性.利用其一级结构所给出的信息,初步提出二级结构模型.     

基于BDNF和NT-3基因部分序列探讨爬行动物系统发生中的若干问题及扬子鳄分类地位

通过两个核基因NT-3基因(约740 bp)和BDNF基因部分序列(约720 bp)的分析,对爬行动物的系统发生关系中鳄类与鸟类和哺乳类系统发生关系、龟类在爬行动物系统发生中的位置以及扬子鳄属的划分等问题进行探讨.结果表明,在NT-3基因序列中,有307个位点存在变异(约为总位点数的47.3%),BDNF基因序列有256个变异位点(约为38.79%);构建的分子系统树显示,NT-3和BDNF基因以及两序列合并数据后所得系统树的拓扑结构均支持鳄类和鸟类聚为一支构成姐妹群,鳄类与蜥蜴类尽管在形态上非常相似,但它们的亲缘关系仍然较远;同时支持把龟鳖类作为鳄类和鸟类支系的姐妹群,支持把蜥蜴类(有鳞类)放在爬行类系统发生树的基部,而不是龟鳖类作为现代爬行类中最基部的1支.对扬子鳄分类地位的研究结果支持在现存的鳄类中扬子鳄与密西西比鳄的亲缘关系较近的结论.     

AN INTERGENERIC HYBRID IN THE SAXIFRAGACEAE: EVIDENCE FROM RIBOSOMAL RNA GENES

The tandemly repeated multigene families encoding the 5S and 18S-25S ribosomal RNAs were studied at the restriction enzyme level in Tolmiea menziesii, Tellima grandiflora, and in a putative intergeneric hybrid. Using restriction endonucleases that cut once per repeat, the repeat lengths of the 5S and 18S-25S ribosomal genes were estimated. The 5S ribosomal gene repeat length is approximately 480 and 450 base pairs, respectively, in Tolmiea and Tellima. The repeat length of the 18S-25S ribosomal genes varied from 11–13 kb in Tolmiea, and was only about 9 kb in Tellima. The putative hybrid combined the repeat lengths of both Tolmiea and Tellima for both the 5S and the 18S-25S ribosomal genes. These data substantiate the occurrence of natural hybridization between Tolmiea and Tellima. For both the 5S and 18S-25S gene experiments, the hybrid appears to contain fewer repeats corresponding to Tolmiea than to Tellima.