Blotting, Southern

Publication Title: 
Biochemical and Biophysical Research Communications

Telomere is the repetitive DNA sequence at the end of chromosomes, which shortens progressively with cell division and limits the replicative potential of normal human somatic cells. L-carnosine, a naturally occurring dipeptide, has been reported to delay the replicative senescence, and extend the lifespan of cultured human diploid fibroblasts. In this work, we studied the effect of carnosine on the telomeric DNA of cultured human fetal lung fibroblast cells.

Author(s): 
Shao, Lan
Li, Qing-Huan
Tan, Zheng
Publication Title: 
Methods in Molecular Biology (Clifton, N.J.)

Chronic hepatitis B remains a substantial public health burden affecting approximately 350 million people worldwide, causing cirrhosis and liver cancer, and about 1 million people die each year from hepatitis B and its complications. Hepatitis B is caused by hepatitis B virus (HBV) infection. As an essential component of the viral life cycle, HBV covalently closed circular DNA (cccDNA) is synthesized and maintained at low copy numbers in the nucleus of infected hepatocytes, and serves as the transcription template for all viral RNAs.

Author(s): 
Cai, Dawei
Nie, Hui
Yan, Ran
Guo, Ju-Tao
Block, Timothy M.
Guo, Haitao
Publication Title: 
The Journal of Protozoology

We have analyzed the macronuclear DNA of Paramecium tetraurelia using orthogonal-field-alternation gel electrophoresis. The mean size of the linear macronuclear DNA molecules is approximately 450 kb. Less than 6% of the macronuclear DNA is larger than 800 kb. Using pulse times of 20, 40, 60 and 90 s we show that the macronuclear fragment containing the A type variable surface antigen gene migrates reproducibly as a 320-kb linear DNA. Over the same pulse times we describe the unusual migration of the ribosomal RNA gene (rDNA) of P. tetraurelia.

Author(s): 
Phan, H. L.
Forney, J.
Blackburn, E. H.
Publication Title: 
Nucleic Acids Research

We report the identification and cloning of the telomeres of the filamentous fungus,Aspergillus nidulans. We have identified three classes of cloned chromosomal ends based on the telomere-associated sequences (TASs) and demonstrated that the telomeric repeat sequence is TTAGGG, identical to that found in vertebrates, including humans, and some lower eukaryotes. One category of telomere clones was found to contain internal, variant TAAGGG repeats. The A.nidulans telomeric tract length is strikingly short (4-22 repeats).

Author(s): 
Bhattacharyya, A.
Blackburn, E. H.
Publication Title: 
Gene

The macronucleus of the ciliate Tetrahymena contains approx. 10(4) ribosomal RNA gene molecules (rDNA) in the form of linear, autonomously replicating palindromes. Previous studies have shown that macronuclear rDNA molecules derived from wild-type (wt) inbred strain C3 out-replicate those derived from wt inbred strain B, in macronuclei initially heterozygous for both, leading to the complete loss of the B rDNA.

Author(s): 
Orias, E.
Larson, D.
Hu, Y. F.
Yu, G. L.
Karttunen, J.
L¯vlie, A.
Haller, B.
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: 
Molecular Biology of the Cell

Mutation of the template region in the RNA component of telomerase can cause incorporation of mutant DNA sequences at telomeres. We made all 63 mutant sequence combinations at template positions 474-476 of the yeast telomerase RNA, TLC1. Mutants contained faithfully incorporated template mutations, as well as misincorporated sequences in telomeres, a phenotype not previously reported for Saccharomyces cerevisiae telomerase template mutants. Although growth rates and telomere profiles varied widely among the tlc1 mutants, chromosome separation and segregation were always aberrant.

Author(s): 
Lin, Jue
Smith, Dana L.
Blackburn, Elizabeth H.
Publication Title: 
Gene

The macronucleus of the ciliate Tetrahymena contains approx. 10(4) ribosomal RNA gene molecules (rDNA) in the form of linear, autonomously replicating palindromes. Previous studies have shown that macronuclear rDNA molecules derived from wild-type (wt) inbred strain C3 out-replicate those derived from wt inbred strain B, in macronuclei initially heterozygous for both, leading to the complete loss of the B rDNA.

Author(s): 
Orias, E.
Larson, D.
Hu, Y. F.
Yu, G. L.
Karttunen, J.
L¯vlie, A.
Haller, B.
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: 
Genetics

The abundant rDNA minichromosome of Tetrahymena thermophila is generated by a series of developmentally controlled processing steps, termed rDNA maturation, during the formation of the new macronucleus in conjugating cells. rDNA maturation involves excision of a region encoding the single copy rRNA gene (rDNA) from its germline location, rearrangement of the rDNA into a palindromic minichromosome, de novo telomere addition, and amplification to approximately 10(4) copies. The rDNA is maintained at this high level in vegetatively growing cells.

Author(s): 
Kapler, G. M.
Orias, E.
Blackburn, E. H.

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