Conjugation, Genetic

Publication Title: 
Cell

The amplification of ribosomal DNA during development of the somatic macronucleus in Tetrahymena thermophila was analyzed by genetic and molecular biological techniques. We have identified an alternate form of the rDNA, structurally distinguishable from the wild-type by an extra cutting site for Bam HI in its nontranscribed spacer. The altered rDNA was inherited in crosses in a simple Mendelian fashion, consistent with the presence of only one rRNA gene copy per haploid genome in the micronucleus.

Author(s): 
Pan, W. C.
Orias, E.
Flacks, M.
Blackburn, E. H.
Publication Title: 
Cold Spring Harbor Symposia on Quantitative Biology
Author(s): 
Blackburn, E. H.
Budarf, M. L.
Challoner, P. B.
Cherry, J. M.
Howard, E. A.
Katzen, A. L.
Pan, W. C.
Ryan, T.
Publication Title: 
Cell

A novel form of extrachromosomal rDNA has been identified in conjugating Tetrahymena cells. This rDNA consists of 11 kb linear double-stranded DNA molecules, each containing a single rRNA gene copy. The DNA sequence, tandemly repeated CCCCAA (Blackburn and Gall, 1978) found at the termini of extrachromosomal palindromic rDNA (the macronuclear form found in vegetatively growing cells), is also present at the corresponding terminus of the 11 kb rDNA.

Author(s): 
Pan, W. C.
Blackburn, E. H.
Publication Title: 
Genetics

The micronuclear genome of Tetrahymena thermophila contains Tel-1 elements that structurally resemble transposons. Here we present molecular evidence that Tel-1 transposon-like elements are mobile. The arrangements of Tel-1 elements in the micronuclear genomes of several T. thermophila strains and cell lines were assayed by Southern blotting. The molecular evidence for Tel-1 transposition is most striking in strains that have undergone unusual laboratory-induced meioses.

Author(s): 
Wyman, C.
Blackburn, E. H.
Publication Title: 
Cell

A novel form of extrachromosomal rDNA has been identified in conjugating Tetrahymena cells. This rDNA consists of 11 kb linear double-stranded DNA molecules, each containing a single rRNA gene copy. The DNA sequence, tandemly repeated CCCCAA (Blackburn and Gall, 1978) found at the termini of extrachromosomal palindromic rDNA (the macronuclear form found in vegetatively growing cells), is also present at the corresponding terminus of the 11 kb rDNA.

Author(s): 
Pan, W. C.
Blackburn, E. H.
Publication Title: 
Molecular and Cellular Biology

We analyzed the extent, reproducibility, and developmental control of genomic rearrangements in the somatic macronucleus of the ciliate Tetrahymena thermophila. To exclude differences caused by genetic polymorphisms, we constructed whole-genome homozygotes, and we compared the homozygous progeny derived from single macronuclear differentiation events. This strategy enabled us to identify a novel form of variable rearrangement and to confirm previous findings that rearranged sequences occur at a high frequency in the Tetrahymena genome.

Author(s): 
Howard, E. A.
Blackburn, E. H.
Publication Title: 
Genetics

The micronuclear genome of Tetrahymena thermophila contains Tel-1 elements that structurally resemble transposons. Here we present molecular evidence that Tel-1 transposon-like elements are mobile. The arrangements of Tel-1 elements in the micronuclear genomes of several T. thermophila strains and cell lines were assayed by Southern blotting. The molecular evidence for Tel-1 transposition is most striking in strains that have undergone unusual laboratory-induced meioses.

Author(s): 
Wyman, C.
Blackburn, E. H.
Publication Title: 
Cold Spring Harbor Symposia on Quantitative Biology
Author(s): 
Blackburn, E. H.
Budarf, M. L.
Challoner, P. B.
Cherry, J. M.
Howard, E. A.
Katzen, A. L.
Pan, W. C.
Ryan, T.
Publication Title: 
Molecular and Cellular Biology

We analyzed the extent, reproducibility, and developmental control of genomic rearrangements in the somatic macronucleus of the ciliate Tetrahymena thermophila. To exclude differences caused by genetic polymorphisms, we constructed whole-genome homozygotes, and we compared the homozygous progeny derived from single macronuclear differentiation events. This strategy enabled us to identify a novel form of variable rearrangement and to confirm previous findings that rearranged sequences occur at a high frequency in the Tetrahymena genome.

Author(s): 
Howard, E. A.
Blackburn, E. H.
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