Ciliates contain two types of nuclei: a micronucleus and a macronucleus. The micronucleus
serves as the germ line nucleus but does not express its genes. The macronucleus provides …

INTRODUCTION of important advantages for the study of eucaryotic DNA replication and
chromosome segregation. In contrast to Eucaryotic chromosomes, each of which consists of …

We have constructed a linear yeast plasmid by joining fragments from the termini of
Tetrahymena ribosomal DNA to a yeast vector. Structural features of the terminus region of …

Telomeres, the ends of eukaryotic chromosomes, have long been recognized as specialized
structures. Their stability compared with broken ends of chromosomes1, 2 suggested that …

Fifty-five-kilobase long artificial chromosomes containing cloned genes, replicators,
centromeres and telomeres have been constructed in yeast. These molecules have many of …

We have used pediiree analysis to investigate the mitotic segregation of circular and linear
DNA plasmids in Saccharomyces cerevisae. Circular ARS plasmids, which bear putative …

Repression of the yeast silent mating type loci requires cis-acting sequences located over 1
kb from the regulated promoters. One of these sites, a “silencer,” exhibits enhancer-like …

Topoisomerase I is associated with DNAase I hypersensitive sites in the nontranscribed
spacers flanking the rRNA genes in Tetrahymena thermophila. The endogenous …

Our understanding of many cellular and molecular phenomena in the yeast Succharomyces
cerevisiae has increased dramatically over the past seven years due largely to the …

Circular recombinant DNA plasmids that contain autonomously replicating sequences
(ARSs) are maintained in extrachromosomal form in transformed yeast cells. However, these …