scholarly journals A Non-Long Terminal Repeat Retrotransposon Family Is Restricted to the Germ Line Micronucleus of the Ciliated Protozoan Tetrahymena thermophila

2004 ◽  
Vol 3 (1) ◽  
pp. 157-169 ◽  
Author(s):  
Jeffrey S. Fillingham ◽  
Trine A. Thing ◽  
Nama Vythilingum ◽  
Alex Keuroghlian ◽  
Deanna Bruno ◽  
...  
Keyword(s):  
Long Terminal Repeat ◽  
Tetrahymena Thermophila ◽  
Germ Line ◽  
Terminal Repeat ◽  
Sexual Cycle ◽  
Northern Analysis ◽  
Ciliated Protozoan ◽  
Dna Rearrangements ◽  
Retrotransposon Family ◽  
The Relationship

ABSTRACT The ciliated protozoan Tetrahymena thermophila undergoes extensive programmed DNA rearrangements during the development of a somatic macronucleus from the germ line micronucleus in its sexual cycle. To investigate the relationship between programmed DNA rearrangements and transposable elements, we identified several members of a family of non-long terminal repeat (LTR) retrotransposons (retroposons) in T. thermophila, the first characterized in the ciliated protozoa. This multiple-copy retrotransposon family is restricted to the micronucleus of T. thermophila. The REP (Tetrahymena non-LTR retroposon) elements encode an ORF2 typical of non-LTR elements that contains apurinic/apyrimidinic endonuclease (APE) and reverse transcriptase (RT) domains. Phylogenetic analysis of the RT and APE domains indicates that the element forms a deep-branching clade within the non-LTR retrotransposon family. Northern analysis with a probe to the conserved RT domain indicates that transcripts from the element are small and heterogeneous in length during early macronuclear development. The presence of a repeated transposable element in the genome is consistent with the model that programmed DNA deletion in T. thermophila evolved as a method of eliminating deleterious transposons from the somatic macronucleus.

scholarly journals Role of Micronucleus-Limited DNA in Programmed Deletion of mse2.9 during Macronuclear Development of Tetrahymena thermophila

2004 ◽  
Vol 3 (2) ◽  
pp. 288-301 ◽  
Author(s):  
Jeffrey S. Fillingham ◽  
Ronald E. Pearlman
Keyword(s):  
Epigenetic Regulation ◽  
Tetrahymena Thermophila ◽  
Germ Line ◽  
Sexual Cycle ◽  
Ciliated Protozoan ◽  
Dna Rearrangements ◽  
Macronuclear Development ◽  
Dna Deletion

ABSTRACT Extensive programmed DNA rearrangements occur during the development of the somatic macronucleus from the germ line micronucleus in the sexual cycle of the ciliated protozoan Tetrahymena thermophila. Using an in vivo processing assay, we analyzed the role of micronucleus-limited DNA during the programmed deletion of mse2.9, an internal eliminated sequence (IES). We identified a 200-bp region within mse2.9 that contains an important cis-acting element which is required for the targeting of efficient programmed deletion. Our results, obtained with a series of mse2.9-based chimeric IESs, led us to suggest that the cis-acting elements in both micronucleus-limited and macronucleus-retained flanking DNAs stimulate programmed deletion to different degrees depending on the particular eliminated sequence. The mse2.9 IES is situated within the second intron of the micronuclear locus of the ARP1 gene. We show that the expression of ARP1 is not essential for the growth of Tetrahymena. Our results also suggest that mse2.9 is not subject to epigenetic regulation of DNA deletion, placing possible constraints on the scan RNA model of IES excision.

scholarly journals A method for mapping germ line sequences in Tetrahymena thermophila using the polymerase chain reaction.

Genetics ◽  
1994 ◽  
Vol 137 (1) ◽  
pp. 95-106 ◽  
Author(s):  
D Cassidy-Hanley ◽  
M C Yao ◽  
P J Bruns
Keyword(s):  
Polymerase Chain Reaction ◽  
Dna Sequences ◽  
Tetrahymena Thermophila ◽  
Germ Line ◽  
Repetitive Sequences ◽  
Mapping Technique ◽  
Ciliated Protozoan ◽  
Chain Reaction ◽  
Polymerase Chain ◽  
Template Dna

Abstract A method for mapping DNA sequences to specific germinal chromosomes in the ciliated protozoan Tetrahymena thermophila has been developed. This mapping technique (PCR mapping) utilizes the polymerase chain reaction and template DNA derived from nullisomic strains to directly assign micronuclear DNA sequences to specific micronuclear chromosomes. Using this technique, a number of unique sequences and short repetitive sequences flanked by unique sequences have been mapped to four of the five germinal chromosomes.

scholarly journals Germ line-specific DNA sequences are present on all five micronuclear chromosomes in Tetrahymena thermophila.

1983 ◽  
Vol 3 (11) ◽  
pp. 1909-1919 ◽  
Author(s):  
K M Karrer
Keyword(s):  
In Situ Hybridization ◽  
Dna Sequences ◽  
Tetrahymena Thermophila ◽  
Germ Line ◽  
Plasmid Vector ◽  
Ciliated Protozoan ◽  
Specific Sequence ◽  
Individual Probe ◽  
Vector Pbr322

The development of the macronucleus from the zygotic micronucleus in the ciliated protozoan Tetrahymena spp. involves the elimination of specific DNA sequences (M. C. Yao and M. Gorovsky, Chromosoma 48:1-18 1974). The present study demonstrates that micronucleus-specific DNA is present on all five of the micronuclear chromosomes. Fragments of micronuclear DNA from Tetrahymena thermophila were cloned in the plasmid vector pBR322. A procedure was developed to examine the organization of the cloned sequences in micro- and macronuclear DNA without nick translating each individual probe. Twenty-three percent of randomly selected DNA sequences examined by this method were micronucleus (germ line) specific. They were all members of families of repeated sequences. Hybridization of six micronucleus-specific DNA sequences to micronuclear DNA from nullisomic strains of T. thermophila, which are lacking one or more pairs of chromosomes in the micronucleus, suggested that these sequences are present on several chromosomes. One micronucleus-specific sequence was shown by in situ hybridization to be present on all five of the micronuclear chromosomes.

scholarly journals Germ line-specific DNA sequences are present on all five micronuclear chromosomes in Tetrahymena thermophila

1983 ◽  
Vol 3 (11) ◽  
pp. 1909-1919
Author(s):  
K M Karrer
Keyword(s):  
In Situ Hybridization ◽  
Dna Sequences ◽  
Tetrahymena Thermophila ◽  
Germ Line ◽  
Plasmid Vector ◽  
Ciliated Protozoan ◽  
Specific Sequence ◽  
Individual Probe ◽  
Vector Pbr322

The development of the macronucleus from the zygotic micronucleus in the ciliated protozoan Tetrahymena spp. involves the elimination of specific DNA sequences (M. C. Yao and M. Gorovsky, Chromosoma 48:1-18 1974). The present study demonstrates that micronucleus-specific DNA is present on all five of the micronuclear chromosomes. Fragments of micronuclear DNA from Tetrahymena thermophila were cloned in the plasmid vector pBR322. A procedure was developed to examine the organization of the cloned sequences in micro- and macronuclear DNA without nick translating each individual probe. Twenty-three percent of randomly selected DNA sequences examined by this method were micronucleus (germ line) specific. They were all members of families of repeated sequences. Hybridization of six micronucleus-specific DNA sequences to micronuclear DNA from nullisomic strains of T. thermophila, which are lacking one or more pairs of chromosomes in the micronucleus, suggested that these sequences are present on several chromosomes. One micronucleus-specific sequence was shown by in situ hybridization to be present on all five of the micronuclear chromosomes.

scholarly journals Molecular Genetic Analysis of an SNF2/brahma-Related Gene in Tetrahymena thermophila Suggests Roles in Growth and Nuclear Development

2006 ◽  
Vol 5 (8) ◽  
pp. 1347-1359 ◽  
Author(s):  
Jeffrey S. Fillingham ◽  
Jyoti Garg ◽  
Nora Tsao ◽  
Nama Vythilingum ◽  
Takamitsu Nishikawa ◽  
...  
Keyword(s):  
Chromatin Remodeling ◽  
Tetrahymena Thermophila ◽  
Germ Line ◽  
Molecular Genetic ◽  
Comparative Sequence Analysis ◽  
Molecular Genetic Analysis ◽  
Northern Analysis ◽  
Related Gene ◽  
Nuclear Development ◽  
Related Proteins

ABSTRACT We used a reverse genetic approach to identify three members of the SNF2 superfamily of chromatin remodeling genes in the ciliated protozoan Tetrahymena thermophila in order to investigate possible functions of ATP-dependent chromatin remodeling factors in growth and nuclear development. Comparative sequence analysis of the gene product of the Tetrahymena brahma-related gene (TtBRG1) indicates it is a member of the SNF2/BRM subgroup of the SNF2 superfamily. Northern analysis suggests that TtBRG1 has roles in growth and nuclear development in Tetrahymena. Indirect immunofluorescence analysis during nuclear development indicates that TtBrg1p localizes to both the parental and developing macronucleus of Tetrahymena during the time period corresponding to genome rearrangements. We generated germ line knockout heterokaryons for TtBRG1 and demonstrated that expression of the gene is required to complete nuclear development of Tetrahymena. In addition, the formation of distinct Pdd1p-containing structures is disturbed during the late stages of conjugation in TtBRG1 germ line knockout heterokaryons. We discuss these results in light of possible roles of SNF2-related proteins in growth and nuclear development of Tetrahymena.

scholarly journals INDUCED RESISTANCE TO 6-METHYLPURINE AND CYCLOHEXIMIDE IN TETRAHYMENA. I. GERM LINE MUTANTS OF T. THERMOPHILA

Genetics ◽  
1978 ◽  
Vol 89 (4) ◽  
pp. 695-702
Author(s):  
Bruce C Byrne ◽  
Trudy B Brussard ◽  
Peter J Bruns
Keyword(s):  
Induced Resistance ◽  
Tetrahymena Thermophila ◽  
Germ Line ◽  
Sexual Cycle ◽  
Marker Genes ◽  
Critical Importance ◽  
Wild Type ◽  
Phenotypic Assortment ◽  
Mutant Lines ◽  
Dominant Genes

ABSTRACT Two new mutant lines of Tetrahymena thermophila (T. pyriformis, syngen 1), each conferring resistance to a different agent, are described. Resistance to cycloheximide and 6-methylpurine are each determined by dominant genes, ChxA2 and Mpr; the traits show phenotypic assortment. The method used to select these mutations, the critical importance of backcrossing to wild type following mutagenesis, and the utility of these marker genes in further mutagenic selection schemes and studies of the sexual cycle of Tetrahymena are noted.

scholarly journals FURTHER EVIDENCE FOR LACK OF GENE EXPRESSION IN THE TETRAHYMENA MICRONUCLEUS

Genetics ◽  
1981 ◽  
Vol 98 (4) ◽  
pp. 747-762
Author(s):  
Kristen A Mayo ◽  
Eduardo Orias
Keyword(s):  
Gene Expression ◽  
Rna Synthesis ◽  
Tetrahymena Thermophila ◽  
Germ Line ◽  
Ciliated Protozoan ◽  
Quantitative Evidence ◽  
Soluble Cell ◽  
Cell Extracts ◽  
Radiometric Assay ◽  
Galactokinase Activity

ABSTRACT Certain galA mutations in the ciliated protozoan Tetrahymena thermophila confer an almost total loss of galactokinase activity in homozygotes. Heterokaryons have been constructed that are homogeneous for the galA1 mutation in the (45n) macronucleus, but which contain a galA  + (2n) micronucleus. Soluble cell extracts prepared from these heterokaryons have been assayed for galactokinase activity, using a radiometric assay for the conversion of galactose to galactose-1-phosphate (gal-1-P). No galactokinase activity attributable to the micronuclear genes is observed in such heterokaryons. These results, obtained with the galA1 marker, provide the first direct, quantitative evidence for the lack of micronuclear (germ line) gene expression in Tetrahymena during vegetative growth, and substantiate the predictions of previous phenotypic observations on heterokaryons and autoradiographic studies of micronuclear RNA synthesis. The generality of this conclusion will be established in the future when other enzymically assayable mutations become available for similar studies.

scholarly journals A small family of elements with long inverted repeats is located near sites of developmentally regulated DNA rearrangement in Tetrahymena thermophila.

1994 ◽  
Vol 14 (9) ◽  
pp. 5939-5949 ◽  
Author(s):  
J M Wells ◽  
J L Ellingson ◽  
D M Catt ◽  
P J Berger ◽  
K M Karrer
Keyword(s):  
Dna Sequences ◽  
Inverted Repeat ◽  
Tandem Repeats ◽  
Tetrahymena Thermophila ◽  
Germ Line ◽  
Inverted Repeats ◽  
Dna Rearrangement ◽  
Dna Rearrangements ◽  
Developmentally Regulated ◽  
Small Family

Extensive DNA rearrangement occurs during the development of the somatic macronucleus from the germ line micronucleus in ciliated protozoans. The micronuclear junctions and the macronuclear product of a developmentally regulated DNA rearrangement in Tetrahymena thermophila, Tlr1, have been cloned. The intrachromosomal rearrangement joins sequences that are separated by more than 13 kb in the micronucleus with the elimination of moderately repeated micronucleus-specific DNA sequences. There is a long, 825-bp, inverted repeat near the micronuclear junctions. The inverted repeat contains two different 19-bp tandem repeats. The 19-bp repeats are associated with each other and with DNA rearrangements at seven locations in the micronuclear genome. Southern blot analysis is consistent with the occurrence of the 19-bp repeats within pairs of larger repeated sequences. Another family member was isolated. The 19-mers in that clone are also in close proximity to a rearrangement junction. We propose that the 19-mers define a small family of developmentally regulated DNA rearrangements having elements with long inverted repeats near the junction sites. We discuss the possibility that transposable elements evolve by capture of molecular machinery required for essential cellular functions.

scholarly journals A small family of elements with long inverted repeats is located near sites of developmentally regulated DNA rearrangement in Tetrahymena thermophila

1994 ◽  
Vol 14 (9) ◽  
pp. 5939-5949
Author(s):  
J M Wells ◽  
J L Ellingson ◽  
D M Catt ◽  
P J Berger ◽  
K M Karrer
Keyword(s):  
Dna Sequences ◽  
Inverted Repeat ◽  
Tandem Repeats ◽  
Tetrahymena Thermophila ◽  
Germ Line ◽  
Inverted Repeats ◽  
Dna Rearrangement ◽  
Dna Rearrangements ◽  
Developmentally Regulated ◽  
Small Family

Extensive DNA rearrangement occurs during the development of the somatic macronucleus from the germ line micronucleus in ciliated protozoans. The micronuclear junctions and the macronuclear product of a developmentally regulated DNA rearrangement in Tetrahymena thermophila, Tlr1, have been cloned. The intrachromosomal rearrangement joins sequences that are separated by more than 13 kb in the micronucleus with the elimination of moderately repeated micronucleus-specific DNA sequences. There is a long, 825-bp, inverted repeat near the micronuclear junctions. The inverted repeat contains two different 19-bp tandem repeats. The 19-bp repeats are associated with each other and with DNA rearrangements at seven locations in the micronuclear genome. Southern blot analysis is consistent with the occurrence of the 19-bp repeats within pairs of larger repeated sequences. Another family member was isolated. The 19-mers in that clone are also in close proximity to a rearrangement junction. We propose that the 19-mers define a small family of developmentally regulated DNA rearrangements having elements with long inverted repeats near the junction sites. We discuss the possibility that transposable elements evolve by capture of molecular machinery required for essential cellular functions.

Sign in / Sign up

Export Citation Format

Share Document