Structural polymorphism of the four-repeat Oxytricha nova telomeric DNA sequences

2009 ◽  
Vol 141 (2-3) ◽  
pp. 180-185 ◽  
Author(s):  
Rashid M. Abu-Ghazalah ◽  
Robert B. Macgregor
Keyword(s):  
Dna Sequences ◽  
Structural Polymorphism ◽  
Telomeric Dna ◽  
Oxytricha Nova

scholarly journals Telomeric DNA sequences in beetle taxa vary with species richness

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Daniela Prušáková ◽  
Vratislav Peska ◽  
Stano Pekár ◽  
Michal Bubeník ◽  
Lukáš Čížek ◽  
...  
Keyword(s):  
Species Richness ◽  
Dna Sequences ◽  
Genome Instability ◽  
Telomeric Sequence ◽  
Dna Repeats ◽  
Telomeric Dna ◽  
Common Pattern ◽  
Telomeric Sequences ◽  
Genomic Changes ◽  
Protective Structures

AbstractTelomeres are protective structures at the ends of eukaryotic chromosomes, and disruption of their nucleoprotein composition usually results in genome instability and cell death. Telomeric DNA sequences have generally been found to be exceptionally conserved in evolution, and the most common pattern of telomeric sequences across eukaryotes is (TxAyGz)n maintained by telomerase. However, telomerase-added DNA repeats in some insect taxa frequently vary, show unusual features, and can even be absent. It has been speculated about factors that might allow frequent changes in telomere composition in Insecta. Coleoptera (beetles) is the largest of all insect orders and based on previously available data, it seemed that the telomeric sequence of beetles varies to a great extent. We performed an extensive mapping of the (TTAGG)n sequence, the ancestral telomeric sequence in Insects, across the main branches of Coleoptera. Our study indicates that the (TTAGG)n sequence has been repeatedly or completely lost in more than half of the tested beetle superfamilies. Although the exact telomeric motif in most of the (TTAGG)n-negative beetles is unknown, we found that the (TTAGG)n sequence has been replaced by two alternative telomeric motifs, the (TCAGG)n and (TTAGGG)n, in at least three superfamilies of Coleoptera. The diversity of the telomeric motifs was positively related to the species richness of taxa, regardless of the age of the taxa. The presence/absence of the (TTAGG)n sequence highly varied within the Curculionoidea, Chrysomeloidea, and Staphylinoidea, which are the three most diverse superfamilies within Metazoa. Our data supports the hypothesis that telomere dysfunctions can initiate rapid genomic changes that lead to reproductive isolation and speciation.

Research Progress in the Typical Structure of Human Telomeric G-Quadruplex

2014 ◽  
Vol 955-959 ◽  
pp. 419-422
Author(s):  
Gui Lin Liu ◽  
Yan Ping Ding ◽  
Yan Ling Wu ◽  
Wen Zhang
Keyword(s):  
Cell Cycle ◽  
Dna Sequences ◽  
Research Progress ◽  
Human Chromosomes ◽  
Telomeric Dna ◽  
Typical Structure ◽  
Special Sequence ◽  
Physiological Processes ◽  
G Quadruplex ◽  
Small Molecule Ligands

Telomeric DNA of human chromosomes plays a significant role in physiological processes such as cell cycle, aging, cancer and genetic stability due to its special sequence and structure. The research on small molecule ligands targeting G-quadruplex formed by such special sequence has attracted considerable attention, and has achieved great breakthrough. In this paper, we summarize the DNA sequences and structures of three kinds of typical human telomeric G-quadruplex, providing an important reference for further research.

Structural Polymorphism of d(GA · TC)n DNA Sequences

1993 ◽  
Vol 233 (4) ◽  
pp. 671-681 ◽  
Author(s):  
J.M. Casasnovas ◽  
D. Huertas ◽  
M. Ortiz-Lombardı́a ◽  
J. Kypr ◽  
F. Azorı́n
Keyword(s):  
Dna Sequences ◽  
Structural Polymorphism

Characterization of two telomeric DNA processing reactions in Saccharomyces cerevisiae

1988 ◽  
Vol 8 (11) ◽  
pp. 4642-4650
Author(s):  
A W Murray ◽  
T E Claus ◽  
J W Szostak
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Division ◽  
Dna Polymerase ◽  
Dna Sequences ◽  
Inverted Repeat ◽  
Telomeric Sequence ◽  
Telomeric Dna ◽  
Telomeric Sequences ◽  
Telomere Elongation

We have investigated two reactions that occur on telomeric sequences introduced into Saccharomyces cerevisiae cells by transformation. The elongation reaction added repeats of the yeast telomeric sequence C1-3A to telomeric sequences at the end of linear DNA molecules. The reaction worked on the Tetrahymena telomeric sequence C4A2 and also on the simple repeat CA. The reaction was orientation specific: it occurred only when the GT-rich strand ran 5' to 3' towards the end of the molecule. Telomere elongation occurred by non-template-directed DNA synthesis rather than any type of recombination with chromosomal telomeres, because C1-3A repeats could be added to unrelated DNA sequences between the CA-rich repeats and the terminus of the transforming DNA. The elongation reaction was very efficient, and we believe that it was responsible for maintaining an average telomere length despite incomplete replication by template-directed DNA polymerase. The resolution reaction processed a head-to-head inverted repeat of telomeric sequences into two new telomeres at a frequency of 10(-2) per cell division.

scholarly journals Characterization of two telomeric DNA processing reactions in Saccharomyces cerevisiae.

1988 ◽  
Vol 8 (11) ◽  
pp. 4642-4650 ◽  
Author(s):  
A W Murray ◽  
T E Claus ◽  
J W Szostak
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Division ◽  
Dna Polymerase ◽  
Dna Sequences ◽  
Inverted Repeat ◽  
Telomeric Sequence ◽  
Telomeric Dna ◽  
Telomeric Sequences ◽  
Telomere Elongation

We have investigated two reactions that occur on telomeric sequences introduced into Saccharomyces cerevisiae cells by transformation. The elongation reaction added repeats of the yeast telomeric sequence C1-3A to telomeric sequences at the end of linear DNA molecules. The reaction worked on the Tetrahymena telomeric sequence C4A2 and also on the simple repeat CA. The reaction was orientation specific: it occurred only when the GT-rich strand ran 5' to 3' towards the end of the molecule. Telomere elongation occurred by non-template-directed DNA synthesis rather than any type of recombination with chromosomal telomeres, because C1-3A repeats could be added to unrelated DNA sequences between the CA-rich repeats and the terminus of the transforming DNA. The elongation reaction was very efficient, and we believe that it was responsible for maintaining an average telomere length despite incomplete replication by template-directed DNA polymerase. The resolution reaction processed a head-to-head inverted repeat of telomeric sequences into two new telomeres at a frequency of 10(-2) per cell division.

scholarly journals Introduction of extra telomeric DNA sequences into Saccharomyces cerevisiae results in telomere elongation.

1989 ◽  
Vol 9 (4) ◽  
pp. 1488-1497 ◽  
Author(s):  
K W Runge ◽  
V A Zakian
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Dna Sequences ◽  
Copy Number ◽  
Plasmid Copy Number ◽  
High Copy Number ◽  
Limiting Factor ◽  
Telomeric Dna ◽  
Base Pairs ◽  
Plasmid Copy ◽  
Telomere Elongation

The termini of Saccharomyces cerevisiae chromosomes consist of tracts of C1-3A (one to three cytosine and one adenine residue) sequences of approximately 450 base pairs in length. To gain insights into trans-acting factors at telomeres, high-copy-number linear and circular plasmids containing tracts of C1-3A sequences were introduced into S. cerevisiae. We devised a novel system to distinguish by color colonies that maintained the vector at 1 to 5, 20 to 50, and 100 to 400 copies per cell and used it to change the amount of telomeric DNA sequences per cell. An increase in the number of C1-3A sequences caused an increase in the length of telomeric C1-3A repeats that was proportional to plasmid copy number. Our data suggest that telomere growth is inhibited by a limiting factor(s) that specifically recognizes C1-3A sequences and that this factor can be effectively competed for by long tracts of C1-3A sequences at telomeres or on circular plasmids. Telomeres without this factor are exposed to processes that serve to lengthen chromosome ends.

Ethidium Probing of the Parallel Double- and Four-stranded Structures Formed by the Telomeric DNA Sequences dG(GT)4G and d(GT)5

2003 ◽  
Vol 20 (6) ◽  
pp. 789-799 ◽  
Author(s):  
Irina A. Beschetnova ◽  
Dmitry N. Kaluzhny ◽  
Mikhail A. Livshits ◽  
Anna K. Shchyolkina ◽  
Olga F. Borisova
Keyword(s):  
Dna Sequences ◽  
Telomeric Dna

scholarly journals TEL2, an essential gene required for telomere length regulation and telomere position effect in Saccharomyces cerevisiae.

1996 ◽  
Vol 16 (6) ◽  
pp. 3094-3105 ◽  
Author(s):  
K W Runge ◽  
V A Zakian
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Dna Sequences ◽  
Transcriptional Repression ◽  
Protein Complexes ◽  
Essential Gene ◽  
Position Effect ◽  
Repeated Sequence ◽  
Telomeric Dna ◽  
Telomere Position Effect ◽  
Telomere Lengthening

The DNA-protein complexes at the ends of linear eukaryotic chromosomes are called the telomeres. In Saccharomyces cerevisiae, telomeric DNA consists of a variable length of the short repeated sequence C1-3A. The length of yeast telomeres can be altered by mutation, by changing the levels of telomere binding proteins, or by increasing the amount of C1-3A DNA sequences. Cells bearing the tel1-1 or tel2-1 mutations, known previously to have short telomeres, did not respond to perturbations that caused telomere lengthening in wild-type cells. The transcription of genes placed near yeast telomeres is reversibly repressed, a phenomenon called the telomere position effect. The tel2-1 mutation reduced the position effect but did not affect transcriptional repression at the silent mating type cassettes, HMRa and HML alpha. The TEL2 gene was cloned, sequenced, and disrupted. Cells lacking TEL2 function died, with some cells arresting as large cells with three or four small protrusions or "blebs."

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