Studies on structures and expressions of highly repetitive sequences in the genomes of higher eukaryotes 高等真核生物ゲノム中の高頻度反復配列の構造と発現に関する研究

博士論文

Total DNAs isolated from several higher animals were transcribed in a HeLa cell extract. Transcription of the total DNAs from rat, mouse and hamster gives a discrete product of 6S RNA (about 180 nucleotides) in addtion to a smeared backgroud, whereas transcription from chick, calf and human DNAs gives a discrete 5S RNA (about 120 nucleotides). In view of the sensitivity to α-amanitin, these transcripts are produced by RNA polymerase III. Fingerprint analyses demonstrated that the 6S RNA species trancribed from rodent DNAs have conserved sequences. We compared the sequences of oligonucleotides of the 6S RNA produced from the mouse total DNA with those of a cloned mouse DNA fragment containing a representative type 2 Alu sequence (B2) which was characterized by Kominami et al. (1983). This result demonstrated that the 6S RNA transcribed from mouse total DNA was in fact the transcript of type 2 Alu sequences. The composition of the oligonucleotides of the 6S RNA transcribed from mouse total DNA seems to reflect precisely that of the consensus sequence of the type 2 Alu family proposed by Krayev et al. (1982). Fingerprints of in vitro transcripts of rat and hamster total DNAs showed nearly identical patterns to that of mouse DNA, confirming that rodents have the repetitive sequence with same length and simlar compositions of oligonucletides. Thus total DNA transcription provides a novel aproach to the detection and analysis of type 2 Alu sequences (Sakamoto et al. 1984).

1985