Study of a haploid yeast strain with an unusually high rDNA content. III. Unequal meiotic segregation of the gamma-DNA fraction.
DNA from different strains of Saccharomyces cerevisiae has been fractionated in preparative Ag+/Cs2-SO4 density gradients. The results show that there are real differences in amount of the nuclear satellite component, the gamma-DNA, from one strain to the other. The gamma-DNA forms a homogeneous dense band that contains all the rDNA, and the amount of gamma-DNA estimated from the gradients can be correlated to amount of rDNA derived from rRNA-DNA hybridizations. By various crossings and sporulations we have obtained diploid and haploid strains with gamma-DNA contents ranging from 7 to 20% of the nuclear DNA. During meiosis, the amount of gamma-DNA appears to segregate in a pattern that indicates unequal crossing over as a possible mechanism for differences in gamma-DNA contents.
D000225:Adenine / Q000378:metabolism; D002467:Cell Nucleus; D004247:DNA / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism*; D004276:DNA, Satellite / Q000235:genetics* / Q000378:metabolism; D005838:Genotype; D006238:Haploidy; D008540:Meiosis; D009691:Nucleic Acid Denaturation; D009693:Nucleic Acid Hybridization; D012335:RNA, Ribosomal / Q000378:metabolism; D012270:Ribosomes; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000378:metabolism; D014498:Uracil / Q000378:metabolism
D004276:DNA, Satellite; D012335:RNA, Ribosomal; D014498:Uracil; D004247:DNA; D000225:Adenine