Previous experiments suggest that mitotic chromosome segregation in some fungi is a nonrandom process in which chromatids of the same replicative age are destined for cosegregation. We have investigated the pattern of chromatid segregation in Saccharomyces cerevisiae by labeling the DNA of a strain auxotrophic for thymidine with 5-bromodeoxyuridine. The fate of DNA strands was followed qualitat...

Successful execution of the meiotic program depends on the timely establishment and removal of sister chromatid cohesion. LAB-1 has been proposed to act in the latter by preventing the premature removal of the meiosis-specific cohesin REC-8 at metaphase I in C. elegans, yet the mechanism and scope of LAB-1 function remained unknown. Here we identify an unexpected earlier role for LAB-1 in promo...

A multisubunit complex, called cohesin, containing Smc1p, Smc3p, Scc1p, and Scc3p, is required for sister chromatid cohesion in mitotic cells. We show here that Smc3p and a meiotic version of Scc1p called Rec8p are required for cohesion between sister chromatids, for formation of axial elements, for reciprocal recombination, and for preventing hyperresection of double-strand breaks during meios...

HE chromosomes of eukaryotes replicate in a semi-conservative manner (TAYLOR, WOODS and HUGHES 1957; PRESCOTT and BENDER 1963). Utilizing this observation, we have studied the segregation of sister chromatids during mitosis of plant and animal cells (LARK, CONSIGLI and MINOCHA 1966; LARK 1967). Autoradiographic measurements of segregation at the second mitosis following incorporation of radioac...

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...

N E of the major objections to the torsion theory of crossing over as pro-0 posed by DARLINGTON (1935) is that it is difficult to comprehend why a break in one chromatid should cause a break to occur in exactly the same position in a chromatid from the homologous chromosome. This objection holds for any mechanism which postulates that crossing over occurs after the duplication of the chromosome...

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