title: Minichromosome formation in Chlorella cells irradiated with electron beams.
abstract: Three minichromosomes, miniP7, miniB7, and miniK4 of 800 kbp, 450 kbp, and 550 kbp, respectively, were obtained from Chlorella vulgaris chromosome I by electron-beam irradiation. Two of them were structurally characterized: MiniP7 was formed by the deletion of an internal 180 kbp close to the right end of chromosome I. The 180-kbp region with a small interspersed nuclear element (SINE)-like element on its left terminus was translocated to another chromosome, leaving a footprint-like structure on miniP7. MiniB7 was a hybrid of chromosome I and another chromosome, retaining the left telomere and the centromere of chromosome I. The centromeric repetitive elements served as a rearrangement point in the miniB7 formation. These examples showed the complicated mechanisms involved in the minichromosome formation. The minichromosomes thus obtained can be useful for isolating the fundamental structural elements of a chromosome. Moreover, they may serve as starting materials or a vector to generate artificial chromosomes carrying useful genes.
authors.affiliation: Department of Molecular Biotechnology, Graduate School of Advanced Sciences of Matter, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima 739-8530, Japan. tayamad@hiroshima-u.ac.jp
authors.forename: Takashi
authors.initials: T
authors.lastname: Yamada
authors.forename: Yuhki
authors.initials: Y
authors.lastname: Fujimoto
authors.forename: Yoshitaka
authors.initials: Y
authors.lastname: Yamamoto
authors.forename: Ken-Ichi
authors.initials: K
authors.lastname: Machida
authors.forename: Minehiro
authors.initials: M
authors.lastname: Oda
authors.forename: Makoto
authors.initials: M
authors.lastname: Fujie
authors.forename: Shoji
authors.initials: S
authors.lastname: Usami
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Nakayama