Cell cycle-dependent specific positioning and clustering of centromeres and telomeres in fission yeast.

Abstract

Abstract. Fluorescence in situ hybridization (FISH) shows that fission yeast centromeres and telomeres make up specific spatial arrangements in the nucleus. Their positioning and clustering are cell cycle regulated. In G2, centromeres cluster adjacent to the spindle pole body (SPB), while in mitosis, their association with each other and with the SPB is disrupted. Similarly, telomeres cluster at the nuclear periphery in G2 and their associations are disrupted in mitosis. Mitotic centromeres interact with the spindle. They remain undivided until the spindle reaches a critical length, then separate and move towards the poles. This demonstrated, for the first time, that anaphase A occurs in fission yeast. The mode of anaphase A and B is similar to that of higher eukaryotes. In nda3 and cut7 mutants defective in tubulin or a kinesin-related motor, cells are blocked in early stages of mitosis due to the absence of the spindle, and centromeres dissociate but remain close to the SPB, whereas in a metaphase-arrested nuc2 mutant, they reside at the middle of the spindle. FISH is therefore a powerful tool for analyzing mitotic chromosome movement and disjunction using various mutants. Surprisingly, in top2 defective in DNA topoisomerase 11, while most chromatid DNAs remain undivided, sister centromeres are separated. Significance of this finding is discussed. In contrast, most chromatid DNAs are separated but telomeric DNAs are not in cut1 mutant. In cut1, the dependence of SPB duplication on the completion of mitosis is abolished. In crm/mutant cells defective in higher-order chromosome organization, the interphase arrangements of centromeres and telomeres are disrupted.T IlE organization of eukaryotic nuclei is designed for the storage and expression of the genetic material that consists of a set of linear chromosomes surrounded by the nuclear membrane . Eukaryotic chromosomal DNAs are highly folded (the 2 x 106-#m -long human genome DNA is stored in a 10-#m-diameter nucleus), even in micro-organisms with small genomes (total yeast DNA is 4,000 #m long and is packed in a 2-#m-diameter nucleus). A number of nuclear proteins may be involved in chromosomal DNA compaction (Gasser and Laemmli, 1987; Earnshaw and Bernat, 1991). Specific DNA sequences may also function in the organizational principles of chromosomal packaging. A question relevant to this problem is whether certain DNA sequences are essential for spatial arrangements of chromosomes in the nucleus. The fission yeast Schizosaccharomyces pombe is an ideal organism in which to address this question, since it has a small genome consisting of only three chromosomes and is amenable to fine genetic analysis (Yanagida, 1989;Nurse, 1990 We recently reported the application of the fluorescence in situ hybridization (FISH) ~ method to this organism (Uzawa and Yanagida, 1992) and suggested its exploitation in the localization of individual DNA sequences within the nucleus. As an initial step towards understanding the principles of nuclear organization in fission yeast, w...

Cell cycle control of spindle elongation

“…20 The replicated DNA is consequently pushed apart towards the cell ends in a similar manner to anaphase B movement in eukaryotes. 21 While anaphase A does take place in both Schizosaccharomyces pombe 22 and Saccharomyces cerevisiae, 23,24 it does not significantly contribute to chromosome segregation and these fungi depend almost entirely on anaphase B (Fig. 1B and D).…”

The nuclear position of pericentromeric DNA of chromosome 11 appears to be random in GO and non-random in G1 human lymphocytes

“…However, during interphase this is much less clear. Recently, Funabiki et al (1993) have found that centromeres were located near the spindle pole body throughout interphase in fission yeast.…”

Analysis of the cell cycle in the budding yeast Candida albicans by positioning of chromosomes by fluorescence in situ hybridization (FISH) with repetitive sequences

“…However, the number of dots observed was far fewer than expected, perhaps because only some telomeres produced signals or because fusion or clustering of telomeres occurred in the nucleus, as was the case in S. pombe (Funabuki et al 1993 (Gilson et al 1993).…”

“…Use of repetitive ribosomal DNA allowed rDNA to be localized in the nucleolar domain adjacent to the region of the chromatin (Uzawa & Yanagida 1992;Guacci et al 1994). Specific positioning and clustering of centromeres and telomeres during the cell cycle have been analysed by FISH in combination with the simultaneous staining of spindle microtubules in fission yeast (Funabuki et al 1993). FISH with sequences unique to specific chromosomes as probes has provided…”