Table II.

Characteristics of Yeast Strains Studied and Their Nucleolar Morphology

		rDNA						Nucleolar morphology (Fig. 7)
Strains		Chromosomal		Plasmid*		Pol I
NOY505		WT		—		WT		a
NOY758		rdnΔ		p-Pol I		WT		b
NOY759		rdnΔ		p-Pol II		WT		c
NOY777		rdnΔ		p-Pol I		rpa12Δ(ts)		c
NOY770		rdnΔΔ		p-Pol I		WT		b
NOY773		rdnΔΔ		p-Pol II		WT		c
NOY780		rdnΔΔ		p-Pol I		rpa12Δ(ts)		c
NOY408-1a		WT‡		p-Pol II (−5S)		rpa135Δ		d
YJV100		p-Pol II (−5S) integrated§		—		rpa135Δ		e

^*p-Pol I, p-Pol II, and p-Pol II (−5S) correspond to pRDN-hyg1, pNOY353, and pNOY102, respectively (see Table I).  

^‡The numbers of chromosomal rDNA repeats in this strain are reduced to ∼20% of the numbers (∼100–150) of the control strain NOY505 (Brewer et al., 1992; Vu, L., and M. Nomura, unpublished experiments).  

^§The fusion gene, GAL7-35S rDNA, is present in 20–25 copies together with 20–25 copies of the native rDNA repeat (Venema et al., 1995).