Journal of Microbiology

Alteration of chromosomal structure within β-Tubulin and flagellar calmodulin genes during differentiation of Naegleria gruberi Amebae into Flagellates: Bok, Jin Woong , Lee, Joo Hun; J. Microbiol. 1995;33(3):222-227.

Abstract: We have examined DNase I sensitivity of β-tubulin and flagellar calmodulin genes which are transiently and coordinately activated differentiation of Naegleria gruberi amebae into flagellates. The DNase I sensitivity of β-tubulin and flagellar calmodulin genes changed in parallel with the changes in transcriptional activity of the respective genes during differentiation. The two genes were resistant to DNase I inamebae stage when transcription of the two genes was inactive. Forty minutes after initiation of differentiation, when the two genes were most actively being transcribed, the two genes showed the highest sensitsivity to DNase I. One hundred and twenty minutes after initiation, the differentiation was completed and transcriptional activity of the two genes decreased to a low level. At this stage, the two genes were resistant to DNase I treatment like the ones at the ameba stage. This change in the DNase I sensitivity of the two genes was not observed when transcription of the two genes was blocked by adding cycloheximide at the beginning of differentiation.

Reorganization of chromatin conformation from an active to an inactive state after cessation of transcription: Lee , Myeong Sok; J. Microbiol. 1996;34(1):54-60.

Abstract: Taking advantage of the heat inducible HSP82 gene in yeast, chromatin structure after transcription cessation was investigated. Alteration of chromating conformation within the HSP82 gene transcription unit into an active state has been shown to correlate with its transcriptional induction. It was thus of interest to examine whether the active chromatin state within the HSP82 mRNA analysis, the gene ceased its transcription within a few hours of cultivation at a normal condition after heat induction. In this condition, an active chromatin conformation in the HSP82 gene body was changed into an inactive state which was revealed by DNase I resistance and by typical nucleosomal cutting periodicity in the corresponding chromatin. These results thus ruled out the possibility of a long-term maintenance of the DNase I sensitive chromatin after transcription cessation. DNA replication may be a critical event for the chromatin reprogramming.

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