Naslov
Chromosome termini of the monocot plant Othocallis siberica are maintained by telomerase which specifically synthesises vertebrate-type telomere sequences

Autori
Weiss-Schneeweiss, Hanna ; Riha, Karel ; Jang, Gee Chang ; Puizina, Jasna ; Scherthan, Harry ; Schweizer, Dieter.

Izvornik
Plant Journal (0960-7412) 137 (2004); 484-493

Vrsta, podvrsta i kategorija rada
Radovi u časopisima, članak, znanstveni

Ključne riječi
Arabidopsis-type telomeric sequences; FISH; Othocallis siberica; telomerase; TRAP assay; vertebrate-type telomeric sequence

Sažetak
We have undertaken complex cytogenetic and molecular analyses on the molecular composition of the telomeres in Othocallis siberica, plant belonging to the monocotiledonous order Asparagales, which was recently shown to lack Arabidopsis-type telomere sequences. Fluorescence in situ hybridization (FISH) revealed the presence of vertebrate-type telomeric sequences TTAGGG at all chromosome termini and few additional regions of O. siberica chromosomes while Arabidopsis-type TTTAGGG DNA and PNA probes did not hybridize to chromosmes of Othocalis, except for pronounced polymorphic blocks in chromosomes 2 (interstitial) and 4 (terminal). These interstitial/terminal regions are apparently composed of large blocks of (TTAGGG)n and (TTTAGGG)n DNA and represent a unique example of interspersion of two types of telomeric repeats within one genome and are perhaps a reflection of the recent evolutionary switch from Arabidopsis-type to vertebrate-type telomeric repeats in this plant group. Southern hybridization revealed the presence of long stretches (more than 10 kb) of vertebrate-type TTAGGG telomeric repeats in O. siberica. BAL31 analysis confirmed the presence of TTAGGG sequences at the molecular chromosome ends of O. siberica. PCR-based telomeric repeat amplification protocol (TRAP assay) followed by cloning of the extension/amplification products confirmed telomerase-dependent addition of TTAGGG repeats in O. siberica and provided proof for the prsence of active telomerase that utilises TTAGGG template to elongate telomeres of Othocalis. Molecular and evolutionary aspects of the change in telomerase active site are discussed.

Izvorni jezik
Engleski

Znanstvena područja
Biologija

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