Immobilization Antigens from Tetrahymena thermophila Are Glycosyl-Phosphatidylinositol-Linked Proteins

Abstract The macronucleus of the ciliate Tetrahymena thermophila contains a fragmented somatic genome consisting of several hundred identifiable chromosome pieces. These pieces are generated by site-specific fragmentation of the germline chromosomes and most of them are represented at an average of 45 copies per macronucleus. In the course of successive divisions of an initially heterozygous macronucleus, the random distribution of alleles of loci carried on these copies eventually generates macronuclei that are pure for one allele or the other. This phenomenon is called phenotypic assortment. We have previously reported the existence of loci that assort together (coassort) and hypothesized that these loci reside on the same macronuclear piece. The work reported here provides new, rigorous genetic support for the hypothesis that macronuclear autonomously replicating chromosome pieces are the physical basis of coassortment groups. Thus, coassortment allows the mapping of the somatic genome by purely genetic means. The data also strongly suggest that the random distribution of alleles in the Tetrahymena macronucleus is due to the random distribution of the MAC chromosome pieces that carry them.

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Glycosyl-Phosphatidylinositol Reanchoring Unmasks Distinct Antigen-Presenting Pathways for CD1b and CD1c

The Journal of Immunology ◽

10.4049/jimmunol.165.3.1272 ◽

2000 ◽

Vol 165 (3) ◽

pp. 1272-1277 ◽

Cited By ~ 11

Author(s):

David H. Geho ◽

John D. Fayen ◽

Robin M. Jackman ◽

D. Branch Moody ◽

Steven A. Porcelli ◽

...

Keyword(s):

Glycosyl Phosphatidylinositol ◽

Antigen Presenting

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Micronuclear DNA sequences from Tetrahymena do not confer mitotic stability on ARS plasmids in Saccharomyces

Genome ◽

10.1139/g88-116 ◽

1988 ◽

Vol 30 (5) ◽

pp. 690-696 ◽

Cited By ~ 3

Author(s):

Wendy H. Horsfall ◽

Ronald E. Pearlman

Keyword(s):

Saccharomyces Cerevisiae ◽

Dna Sequences ◽

Copy Number ◽

Tetrahymena Thermophila ◽

Assay System ◽

Mitotic Stability ◽

Yeast Saccharomyces Cerevisiae ◽

Genomic Libraries ◽

Ade2 Gene

Genomic libraries containing micronuclear DNA sequences from Tetrahymena thermophila have been constructed in a vector containing ARS1, SUP11, and ura3 sequences from the yeast Saccharomyces cerevisiae. When transformed into a strain of S. cerevisiae carrying a suppressible ochre mutation in the ade2 gene, viable transformants are obtained only if the transforming plasmid is maintained at a copy number of one or two per cell. Mitotic segregation of the plasmid is easily assessed in a colour assay of transformants. Using this assay system, we showed that micronuclear DNA from Tetrahymena does not contain sequences that confer mitotic stability on yeast ARS-containing plasmids; i.e., sequences that function analogously to yeast centromere sequences. One transformant was analyzed that carries Tetrahymena sequences that maintain the copy number of the ARS plasmid at one or two per cell. However, these sequences do not confer mitotic stability on the transformants and they confer a phenotype in this assay similar to that of the REP3 gene of the yeast 2 μm plasmid.Key words: mitotic stability, centromere, Tetrahymena, Saccharomyces.

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