Tetrahymena

Abstract

Tetrahymena is a genus of mostly free‐living ciliated protozoa that is intensively employed to investigate and solve fundamental problems in molecular, cellular and developmental biology. Like all ciliates, Tetrahymena contains separate germline and somatic nuclei, known as the micronucleus and macronucleus, respectively. The macronucleus is derived from a copy of the micronucleus through a process that involves extensive programmed whole‐genome rearrangement and is under intensive study. The most highly developed experimental model species is Tetrahymena thermophila , which can be readily manipulated using the tools of genetics, molecular biology, cell biology and biochemistry. Notable discoveries made using Tetrahymena include the structure of telomeres and telomerase, self‐splicing RNA, the first microtubular motor and the link between histone acetylation and gene regulation. The approximately 104 Megabase macronuclear genome of T. thermophila has been sequenced and annotated; the micronuclear genome sequence will be completed soon. Key Concepts: Tetrahymena are large, elaborate eukaryotic cells with many experimental advantages and well‐suited to the study of cellular structure, division and development. Tetrahymena have been studied for nearly a century and been the source of a number of groundbreaking discoveries. A characteristic feature of Tetrahymena , and the basis of much biological interest, is the separation of germline and somatic genetic functions into separate nuclei. Programmed genome rearrangement in Tetrahymena shares common mechanistic features with heterochromatic gene silencing in other eukaryotes. Applying the modern tools of genomics and proteomics has facilitated research with Tetrahymena and opened up new areas of investigation.