title: Sister chromatids are often incompletely aligned in meristematic and endopolyploid interphase nuclei of Arabidopsis thaliana.
abstract: We analyzed whether sister chromatids are continuously aligned in meristematic and endopolyploid Arabidopsis interphase nuclei by studying sister-chromatid alignment at various chromosomal positions. FISH with individual BACs to flow-sorted 4C root and leaf nuclei frequently yielded more than two hybridization signals, indicating incomplete or absent sister-chromatid alignment. Up to 100% of 8C, 16C, and 32C nuclei showed no sister-chromatid alignment at defined positions. Simultaneous FISH with BACs from different chromosomal positions revealed more frequent sister-chromatid alignment in terminal than in midarm positions. Centromeric positions were mainly aligned up to a ploidy level of 16C but became separated or dispersed in 32C nuclei. DNA hypomethylation (of the whole genome) and transcriptional activity (at FWA gene position) did not impair sister-chromatid alignment. Only 6.1% of 4C leaf nuclei showed sister-chromatid separation of the entire chromosome 1 top arm territories. Homozygous transgenic tandem repeat (lac operator) arrays showing somatic homologous pairing more often than average euchromatic loci did not promote an increased frequency of sister-chromatid alignment. The high frequency of separated sister-chromatid arm positions in > or =4C nuclei suggests that sister-chromatid cohesion is variable, dynamic, and not obligatory along the entire chromosome arm in meristematic and differentiated Arabidopsis nuclei.
authors.affiliation: Institute of Plant Genetics and Crop Plant Research (IPK), D-06466 Gatersleben, Germany. schubert@ipk-gatersleben.de
authors.forename: Veit
authors.initials: V
authors.lastname: Schubert
authors.forename: Marco
authors.initials: M
authors.lastname: Klatte
authors.forename: Ales
authors.initials: A
authors.lastname: Pecinka
authors.forename: Armin
authors.initials: A
authors.lastname: Meister
authors.forename: Zuzana
authors.initials: Z
authors.lastname: Jasencakova
authors.forename: Ingo
authors.initials: I
authors.lastname: Schubert
mesh_terms: D017360:Arabidopsis / Q000235:genetics* / Q000254:growth & development; D002467:Cell Nucleus / Q000235:genetics*; D002503:Centromere; D032461:Chromosomes, Plant / Q000235:genetics; D019175:DNA Methylation; D018744:DNA, Plant / Q000737:chemistry / Q000235:genetics; D018745:Genome, Plant; D007399:Interphase; D007763:Lac Operon / Q000502:physiology; D018519:Meristem / Q000235:genetics*; D011003:Ploidies; D012854:Sister Chromatid Exchange / Q000235:genetics*; D020080:Tandem Repeat Sequences
chemical_list: D018744:DNA, Plant