It is known that mutations in gene SIR2 increase and those in FOB1 decrease recombination within rDNA repeats as assayed by marker loss or extrachromosomal rDNA circle formation. SIR2-dependent chromatin structures have been thought to inhibit access and/or function of recombination machinery in rDNA. We measured the frequency of FOB1-dependent arrest of replication forks, consequent DNA double...

The activity of rRNA genes (rDNA) is regulated by pathways that target the transcription machinery or alter the epigenetic state of rDNA. Previous work has established that downregulation of rRNA synthesis in quiescent cells is accompanied by upregulation of PAPAS, a long noncoding RNA (lncRNA) that recruits the histone methyltransferase Suv4-20h2 to rDNA, thus triggering trimethylation of H4K2...

background and objectives: chlorophyceae are important constituents of marine phytoplankton. the taxonomy of chlorophyceae was traditionally based solely on morphological characteristics. in the present research project, genetic diversity was investigated to analyze five species of chlorophyceae from waters of the persian gulf. materials and methods:   a clone library of the ribosomal small sub...

For the dinoflagellates, an important group of single-cell protists, some nuclear rDNA phylogenetic studies have reported the discovery of rDNA pseudogenes. However, it is unknown if these aberrant molecules are confined to free-living taxa or occur in other members of the group. We have cultured a strain of symbiotic dinoflagellate, belonging to the genus Symbiodinium, which produces three dis...

The family Dermateaceae belongs to the Helotiales order, class Leotiomycetes, and consists of 14 genera. In this study, we introduce new genus Pseudoxenochalara gen. nov. family, which is supported by morphological observations multilocus phylogenetic analysis. Partial sequences loci encoding ?-tubulin (BenA), ribosomal polymerase II second largest subunit (RPB2), 28S rDNA (LSU) internal transc...

The reexamination of the fungal genus Botryosphaeria on 12 plant species 10 families was carried out based molecular phylogenetic analyses using regions translation elongation factor 1-α, β-tubulin, DNA-directed RNA polymerase II subunit, and internal transcribed spacer region rDNA morphological characteristics. Japanese isolates were divided into five clades include dothidea, B. qingyuanensis,...

A microsporidium that closely resembles Paranosema species at the level of the light microscope was isolated from the rusty grain beetle, Cryptolestes ferrugineus. It's identity as Nosema oryzaephili (originally described from Oryzaephilus surinamensis) was confirmed by comparison with a known isolate of N. oryzaephili based on spore size, small subunit rDNA sequence, and relative infectivity t...

To examine relationships among spirotrich ciliates using multi-locus sequence analyses and to provide preliminary insights into molecular diversity within species, we sequenced the small subunit rDNA (SSU rDNA), 5.8S rDNA, alpha-tubulin and the internally transcribed spacer regions (ITS1 and ITS2) of the rDNA genes from seven choreotrich (Class: Spirotrichea) and three oligotrich (Class: Spirot...

Silencing within the yeast ribosomal DNA (rDNA) repeats protects the integrity of this highly repetitive array by inhibiting hyperrecombination and repressing transcription from foreign promoters. Using affinity purification combined with highly sensitive mixture mass spectrometry, we have analyzed the protein interaction network involved in suppressing homologous recombination within the rDNA ...

The genomic stability of the rDNA tandem array is tightly controlled to allow sequence homogenization and to prevent deleterious rearrangements. In this report, we show that the absence of the yeast CTD kinase I (CTDK-I) complex in null mutant strains leads to a decrease in the number of tandem rDNA repeats. Reintroduction of the missing gene induces an increase of rDNA repeats to reach a copy ...