| Summary: | 博士 === 國立中興大學 === 生物科技學研究所 === 102 === Proper transmission of DNA in dividing cells is crucial for the survival of eukaryotic organisms. During cell division, faithful segregation of replicated chromosomes requires their tight attachment, known as sister chromatid cohesion, until anaphase. Sister chromatid cohesion is established during S-phase in a process that requires an acetyltransferase that in yeast is known as Establishment of cohesion 1 (Eco1). Inactivation of Eco1 typically disrupts chromosome segregation and homologous recombination dependent DNA repair in dividing cells ultimately resulting in lethality. We report here the isolation and detailed characterization of two homozygous T-DNA insertion mutants for the Arabidopsis thaliana Eco1 homologue, CHROMOSOME TRANSMISSION FIDELITY 7/ ESTABLISHMENT OF COHESION 1 (CTF7/ECO1), called ctf7-1 and ctf7-2. Mutants exhibited dwarfism, poor anther development and sterility. Analysis of somatic tissues by flow cytometry, scanning electron microscopy and QPCR identified defects in DNA repair and cell division, including an increase in the area of leaf epidermal cells, an increase in DNA content, and the upregulation of genes involved in DNA repair including BRCA1 and PARP2. No significant change was observed in the expression of genes that influence entry into the endocycle. Analysis of meiocytes identified changes in chromosome morphology and defective segregation; reduced cohesion at centromeres and a reduction in the abundance of chromosomal-bound cohesion subunits. Transcript levels for several meiotic genes, including the recombinase genes, DMC1 and RAD51C, and the S-phase licensing factor, CDC45 were elevated in mutant anthers. Moreover QPCR in vegetative tissues indicated upregulation of transposable elements COPIA28 and soloLTR, which suggest an additional role for CTF7/ECO1 in gene silencing. Taken together our results demonstrate that Arabidopsis CTF7/ECO1 plays important roles in preservation of genome integrity and meiosis.
|
|---|
