Cytological characterization of NOR in the bivalent of Saccharomyces cerevisiae.
We cytologically characterized the nucleolar organizer region (NOR) on the bivalent in the yeast Saccharomyces cerevisiae. We used staining with 4'-6-diamidino-2-phenylindole (DAPI), chromomycin A3, and silver nitrate and in situ hybridization technique and utilized a video-intensified microscope system with an ultra-high-sensitive video camera. The results showed that of 16 bivalents of S. cerevisiae, the longest was a recognizable nucleolar chromosome which has an annular and synaptonemal complexless NOR in its submedian portion. The NOR was comprised of 2.65 X 10(9) D DNA which corresponded to 118 copies per haploid of rDNA repeating units. This evidence is discussed in terms of the possible participation of the annular NOR in suppressing the meiotic recombination of the rDNA gene clusters.
Kuroiwa
T
T
Miyamura
S
S
Kawano
S
S
Hizume
M
M
Tho-E
A
A
Miyakawa
I
I
Sando
N
N
D014128:Chromomycin A3; D004275:DNA, Ribosomal / Q000502:physiology; D007211:Indoles; D008856:Microscopy, Fluorescence; D009697:Nucleolus Organizer Region / Q000648:ultrastructure*; D012335:RNA, Ribosomal / Q000502:physiology; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000648:ultrastructure*; D012835:Silver Nitrate; D013194:Staining and Labeling
D004275:DNA, Ribosomal; D007211:Indoles; D012335:RNA, Ribosomal; C007293:DAPI; D012835:Silver Nitrate; D014128:Chromomycin A3