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T Thatcher

Publications and source records attributed to T Thatcher.

3 recordsLinked to original sources
PubMed1988

A conditional mutant having paralyzed cilia and a block in cytokinesis is rescued by cytoplasmic exchange in Tetrahymena thermophila.

Nineteen mutants that are conditional for both the ability to regain motility following deciliation and the ability to grow were isolated. The mutations causing slow growth were placed into five complementation groups. None of the mutations appears to affect energy production as all mutants remained motile at the restrictive temperature. In three complementation groups protein synthesis and the levels of mRNA encoding alpha-tubulin or actin were largely unaffected at the restrictive temperature, consistent with the hypothesis that mutations in these three groups directly affect the assembly of functional cilia and growth. Complementation group 1 was chosen for further characterization. Both phenotypes were shown to be linked, suggesting they are caused by a single mutation. Group 1 mutants regenerated cilia at the restrictive temperature, but the cilia were nonmotile. This mutation also caused a block in cytokinesis at the restrictive temperature but did not affect nuclear divisions or DNA synthesis. The block in cell division was transiently rescued by wild-type cytoplasm exchanged when mutants were paired with wild-type cells during conjugation (round 1 of genomic exclusion). Thus, at least one mutation has been isolated that affects assembly of some microtubule-based structures in Tetrahymena (cilia during regeneration) but not others (nuclei divide at 38 degrees), and the product of this gene is likely to play a role in both ciliary function and in cytokinesis.

Actins↗
PubMed1988

A temperature-sensitive mutation affecting cilia regeneration, nuclear development, and the cell cycle of Tetrahymena thermophila is rescued by cytoplasmic exchange.

A temperature-sensitive mutation was isolated that blocks cilia regeneration and arrests growth in Tetrahymena thermophila. Protein and RNA synthesis and ATP production appeared to be largely unaffected at the restrictive temperature, suggesting that the mutation is specific for cilia regeneration and growth. At the restrictive temperature, mutant cells arrested at a specific point in the cell cycle, after macronuclear S phase and shortly before micronuclear mitosis. Arrested cells did not undergo nuclear divisions, DNA replication, or cytokinesis, so the mutation appears to cause true cell cycle arrest. Surprisingly, the mutation does not appear to affect micronuclear mitosis directly but rather some event(s) prior to micronuclear mitosis that must be completed before cells can complete the cell cycle. The cell cycle arrest was transiently complemented by wild-type cytoplasm exchanged during conjugation with a wild-type cell. Each starved, wild-type cell apparently contained enough rescuing factor to support an average of six cell divisions. Thus, this mutation affects assembly and/or function of at least one but not all of the microtubule-based structures in T. thermophila.

Animals↗