Words similar to tetrahymena
Example sentences for: tetrahymena
How can you use “tetrahymena” in a sentence? Here are some example sentences to help you improve your vocabulary:
Although chromatid breakage requires an endonuclease activity, the cutter, directed by a Cbs-binding activity, no Cbs-dependent "binder/cutter" activity has been detected in vitro . The cutter could be an activity of telomerase itself [ 39 43 ] . Telomerase of both Tetrahymena and Euplotes has a single-strand endonuclease activity [ 45 43 ] . It can trim potential primers back, so that the 3' terminus pairs with template RNA [ 46 ] . Thus, while it may serve a 3' editing function, the existence of a nuclease activity in potential proximity to the site of chromatid breakage is provocative, suggesting that telomerase provides the
Thus, in Tetrahymena and Paramecium telomeres are added at a heterogeneous collection of clustered sites, which we here refer to as "multi-TAS regions," whereas in E. crassus only one TAS is used for each MAC-destined end ("single TAS regions").
Tetrahymena telomerase and the binder/cutter appear to act concertedly in vivo , as if in a physical complex [ 48 49 ] . However, this contrasts with in vitro properties of the enzyme from exconjugants: 1.) it acts on non-telomeric primers [ 44 50 ] , and 2.) it apparently is no larger than the vegetative enzyme [ 44 ] . Furthermore, telomerase can act in the vegetative MAC of Paramecium , uncoupled from chromatid breakage [ 51 ] . It remains to be seen if a complex between telomerase and binder/cutter activity does exist.
The in vitro properties of telomerase are consistent with its known role in creation of MAC telomeres in Tetrahymena [ 41 ] , as well as, presumably, in all other ciliates [ 9 ] . Telomerases from exconjugants of Tetrahymena and Euplotes have been extensively studied in vitro . The E. crassus enzyme can only act on oligomers that pair with telomerase template RNA at their 3' terminus, unless assisted by a dissociable factor (chromosome healing factor), which contributes extra mass to the enzyme in exconjugants [ 42 ] . Telomerase, assisted by this factor, still requires a block of dGs or telomere repeats internal to the 3' primer end [ 43 ] . In contrast, the Tetrahymena exconjugant enzyme can add to a primer completely devoid of telomere repeats in special reaction conditions, and shows no evidence of increased mass beyond that of the vegetative enzyme [ 44 ] .
The exact nucleotide positions where telomere repeats are added have been examined in several ciliates (reviewed by [ 23 53 ] ). Cloned chromosome ends from 81 MAC family indicated heterogeneity of TAS placement, which we attributed to exonuclease erosion of the broken ends prior to telomerase action [ 27 ] . Analogous multi-TAS regions have been described in Tetrahymena ( [ 49 ] ; E. Hamilton and E. Orias, pers.
Loading...