R-loop and restriction mapping procedures reveal the organization of coding regions at each end of the giant rDNA palindrome of Physarum polycephalum. A 19S coding region of 2.10 +/- 0.21 kb is located at each end of a very long central spacer (35.64 +/- 2.08 kb). An internal spacer of 1.66 +/- 0.12 kb lies distal to the 19S gene. The 5.8S rRNA coding region is located in this spacer. The 26S g...

Detailed analysis of variation in intergenic spacer (IGS) and internal transcribed spacer (ITS) regions of rDNA drawn from natural populations of Drosophila melanogaster has revealed contrasting patterns of homogenization although both spacers are located in the same rDNA unit. On the basis of the role of IGS regions in X-Y chromosome pairing, we proposed a mechanism of single-strand exchanges ...

Protein B23 is an abundant nucleolar protein and a putative ribosome assembly factor which possesses an intrinsic ribonuclease activity. In the current work, the effects of RNA sequence and secondary structure on the cleavage preference by protein B23 were studied. Protein B23 ribonuclease preferentially cleaved the single-stranded homopolymers poly(A), poly(U) and poly(C). However, double-stra...

ABSTRACT Ceratocystis fimbriata is a complex of many cryptic, host-specialized species that causes wilt and canker of woody species and rot diseases of storage roots and corms of many economically important plants worldwide. With the exception of the family Araceae, all confirmed hosts of C. fimbriata are dicotyledonous plants. We hypothesized that the isolates from members of the family Aracea...

Aeromonas hydrophila is an important bacterial pathogen which causes the hemorrhagic septicemia in fishes, amphibians and humans. Genetic relationships of diverse isolates of A. hydrophila were recovered from fish and water sources. These isolates were investigated by flanked region of 16S and 23S Ribosomal DNA (rDNA) internal transcribed spacer (ITS). Here we analyzed polymorphism of PCR-ampli...

Black yeasts morphologically identified as Exophiala cf. spinifera were re-analyzed on the basis of morphology, nutritional physiology and ITS rDNA sequencing data. Ribosomal small subunit (SSU) DNA sequence data confirmed that strains belonged to a clade containing the ex-type strain of E. spinifera. Variation in the Internal Transcribed Spacer (ITS) region of the rDNA was studied within this ...

The ribosomal DNA (rDNA) cluster of insects contains several hundred repeating structural-functional units and, therefore, is a typical example of a multigene family. Eukaryotic ribosomal RNA (rRNA) genes (18S, 5.8S, and 28S like) are arranged in tandemly repeated clusters in the nucleolus organizers, separated by several spacers, namely the nontranscribed spacer, the external transcribed space...

30 milled rice samples were collected from retailers in four states of malaysia. these samples were evaluated for eurotium spp. contaminations by direct plating on malt extract salt agar (mesa). all eurotium were isolated and identified based on morphology and nucleotide sequences of internal transcribed spacer 1 (its1) and its2 of the rdna. four eurotium species (e. rubrum, e. amstelodami, e. ...

The application of nuclear rDNA ITS sequences in plant phylogeny and evolution analysis was discussed in this paper. Nuclear rDNA is an important nuclear gene fragment, which had been widely used in phylogenetic studies. The internal transcribed spacer of nuclear rDNA was divided into ITS1 and ITS2 by 5.8S rDNA. The length of ITS1 ranges from 165 bp to 298 bp in angiosperms, and the length of I...