Molecular Phylogeny Of Peritrich And Oligotrich Ciliates And Cloning Of Histone H3 Genes From Euplotes Vannus

Molecular Phylogeny: Researching on the highly conservative sequence of SSU rRNA and more variable ITS domain has become an important method to study phylogenetics on the ciliated. However, its phylogeny still remains confusing as regards the evolutionary relationships and systematic positions of many well-known groups. This is due to the high diversity of their morphology, the loss of intermediate forms during the long period of evolution and insufficient molecular sequence information.Based on the gene sequencing and analyses, this work resolved some confusions of morphologic taxonomy and phylogenetic positions of some key taxa within two classes at the genetic level, 19 strains of 18 species.1. Spirotrichea(1) All tintinnids analyzed belong to a single assemblage, hyaline and agglutinated loricae do not characterize distinct lineages.(2) Amphorellopsis acuta groups with Tintinnidium mucicola but not with Eutintinnus, indicating the traditional family Tintinnidae might be a paraphyletic group.(3) Stenosemella and Codonellopsis are clearly most related and possibly may be even merged into one genus regarding their similar morphology and the molecular analyses and possession of a hyaline collar is only the characteristic of genus.(4) Infraciliature is a reliable character for strombidiids.(5) An exclusion of the Halteriia from the Oligotrichia, as suggested by Strüder-Kypke and Lynn (2003) seems to be premature.2. Oligohymenophorea(1) The genus Zoothamnium maybe is paraphylogenetic, which shows a closely relationship to Zoothamnopsis.(2) Epicarchesium is in an isolated position on the phylogenetic tree and more closely relationship to Pseudovorticella than to Carchesium. This suggests that the silverline system is a more informative character than that of coloniality for determining genus-level phylogenetic relationships among peritrichs.Cloning of histone H3 genes: Euplotes ciliates have two different kinds of histone H3. One functions only during the sexual phase of the life cycle and it is named meiotic/polytene-specific H3. Transcripts of the other gene accumulate primarily during vegetative growth and named vegetative H3. The meiotic/polytene-specific H3 may play a key role in the chromatin remodeling which result in transcriptional activation of macronuclear genes and/or elimination of the majority of the micronuclear genomic sequences. The histone H3 genes were amplified from macronuclear DNA of Euplotes vannus. The polytene stage gene is on a 648-bp molecule and the open reading frame is capable of encoding a 151-amino acid histone H3-like protein. The vegetative gene is carried on a 1.7-kb molecule and encodes a normal sized histone H3 protein of 136 amino acids...