Vesicomyid clams depend entirely on sulfur-oxidizing endosymbiotic bacteria for their nutriment. Endosymbionts that are transmitted cytoplasmically through eggs, such as these, should exhibit a phylogenetic pattern that closely parallels the phylogeny of host mitochondrial genes. Such parallel patterns are rarely observed, however, because they are obscured easily by small amounts of horizontal...

The Tetrahymena thermophila origin recognition complex (ORC) contains an integral RNA subunit, 26T RNA, which confers specificity to the amplified ribosomal DNA (rDNA) origin by base pairing with an essential cis-acting replication determinant--the type I element. Using a plasmid maintenance assay, we identified a 6.7 kb non-rDNA fragment containing two closely associated replicators, ARS1-A (0...

Sequences of 18S ribosomal DNA (rDNA) are increasingly being used to infer phylogenetic relationships among living taxa. Although the 18S rDNA belongs to a multigene family, all its copies are kept homogeneous by concerted evolution (Dover 1982; Hillis and Dixon 1991). To date, there is only one well-characterized exception to this rule, the protozoan Plasmodium (Gunderson et al. 1987; Waters, ...

Like bacteria, fungi play an important role in the soil ecosystem. As only a small fraction of the fungi present in soil can be cultured, conventional microbiological techniques yield only limited information on the composition and dynamics of fungal communities in soil. DNA-based methods do not depend on the culturability of microorganisms, and therefore they offer an attractive alternative fo...

One characteristic of Indo-Pacific Acropora spp. is extremely high diversity in rDNA sequences at both the species and individual levels. In order to test the hypothesis that pseudogenes may contribute to this diversity, three kinds of analyses were conducted. First, for A. millepora (the species containing the most diverse suite of rDNA types), RT-PCR was used to determine which 5.8S rDNA type...

Effort was made to identify Naegleria strains isolated from organs of fish, using phylogenetic analyses of SSU rDNA and ITS sequences. Eighteen fish-isolated strains studied enlarged substantially the so far available set of Naegleria strains characterized by both molecular markers. The phylogenetic analyses of separate and concatenated SSU rDNA and ITS sequences revealed phylogenetic relations...

In all eukaryotes, the ribosomal RNA genes are stably inherited redundant elements. In Drosophila melanogaster, the presence of a Ybb(-) chromosome in males, or the maternal presence of the Ribosomal exchange (Rex) element, induces magnification: a heritable increase of rDNA copy number. To date, several alternative classes of mechanisms have been proposed for magnification: in situ replication...

Abstract Species of Trichogramma Westwood, 1833 (Hymenoptera: Trichogrammtidae) are frequently used as biological control agents against Lepidoptera, but practical application these egg endoparasitoids complicated because their complex taxonomy. This study aimed to compare sequences internal transcribed spacer regions ribosomal DNA (ITS2-rDNA) accessions with those deposited in GenBank order ac...

Studies were conducted on the improvement of A. culicicola identification. This species is phenotypically very similar to A. veronii biotype sobria, A. sobria, and A. allosaccharophila. The sequences of 16S rDNA of A. culicicola isolates show the highest similarity with A. jandaei, A. veronii, and A. caviae. Digestion of 16S rDNA PCR product with AluI and MboI restriction endonucleases allowed ...

High-throughput sequencing of ribosomal RNA gene (rDNA) amplicons has opened up the door to large-scale comparative studies of microbial community structures. The short reads currently produced by massively parallel sequencing technologies make the choice of sequencing region crucial for accurate phylogenetic assignments. While for 16S rDNA, relevant regions have been well described, no truly s...