The transcription of ribosomal RNA genes (rDNA) is a rate-limiting step in ribosome biogenesis and changes profoundly in response to environmental conditions. Recently we reported that JmjC demethylase KDM2A reduces rDNA transcription on starvation, with accompanying demethylation of dimethylated Lys 36 of histone H3 (H3K36me2) in rDNA promoter. Here, we characterized the functions of two domai...

Phytoplankton cells and resting cysts of the species Scrippsiella trochoidea are regular and dominant components of the dinoflagellate flora of coastal marine waters and sediments around the world. This species is a common harmful bloom forming species in coastal waters. In this study, for the first time cyst of S. trochoidea were isolated from the sediments of southeast coast of Iran...

Transcriptional silencing in Saccharomyces cerevisiae occurs at the silent mating-type loci HML and HMR, at telomeres, and at the ribosomal DNA (rDNA) locus RDN1. Silencing in the rDNA occurs by a novel mechanism that depends on a single Silent Information Regulator (SIR) gene, SIR2. SIR4, essential for other silenced loci, paradoxically inhibits rDNA silencing. In this study, we elucidate a re...

Using a dataset comprising 5.8S rDNA sequences from a wide range of fungi, we show that some sequences reported recently from the arbuscular mycorrhizal (AM) fungus Scutellospora castanea most likely originate from Ascomycetes. Other ITS and 5.8S sequences which were previously reported are confirmed as being clearly of mycorrhizal origin and are variable within one isolate of S. castanea. Howe...

Eco-RI-A fragments of the human ribosomal RNA gene family from two types of tissue and three individuals were cloned in lambda vectors and compared by restriction enzyme digestion and electron microscopy. The EcoRI fragment A contains (i) 0.2 kb of the 3' end of the 18S rDNA, (ii) 2.5 kb of internal transcribed spacer and the 5.8S rDNA, and (iii) 4.6 kb of the 28S rDNA gene. All of the six clon...

Genomic instability is a conserved factor in lifespan reduction, although the molecular mechanism is not known. Studies in the yeast Saccharomyces cerevisiae over the past 20 years have found a connection between the ribosomal RNA gene cluster (rDNA) and lifespan. The highly repetitive rDNA exhibits genomic instability, and the antiaging histone deacetylase gene SIR2 regulates this instability....