Cillates Clause Samples

Cillates. Cilliates form a class of Protists that are free living, ciliated, single celled organisms. Ciliates are binucleated, containing two nuclei that are distinct both morphologically and functionally. The smaller micronucleus is the germline nucleus, while the larger macronucleus is the somatic nucleus. The macronucleus is polyploid, containing many mini-chromosomes that independently replicate. Gene expression during vegetative growth is regulated from the macronucleus. The micronucleus is relatively inactive during vegetative growth but is responsible for sexual reproduction and, after reproduction, gives rise to a new macronucleus (reviewed in (Orias, Cervantes et al. 2011)). The best characterized Ciliate is Tetrahymena thermophila, which has been extensively used as a model organism to investigate nuclear functions. In T. thermophila, different cargo proteins are transported to the micro and macro nuclei. This is achieved by nucleus-specific Nup incorporation. The NPCs of the micro and macro nuclei share the same overall architecture and the core structural Nups. However, distinct isoforms of other Nups are specifically incorporated into NPCs of each nucleus; this allows distinct Kapα homologs to be targeted to the micro and macro nucleus (▇▇▇▇▇▇, Falkowska et al. 2008, Iwamoto, Mori et al. 2009). By mislocalizing nucleus-specific Nups to the wrong nucleus, the localization of cargo proteins can be reversed (Iwamoto, Mori et al. 2009). Thus, Tetrahymena, and possibly all ciliates, achieve differences among nuclei in a single cytoplasm by regulating the composition of NPCs in each nucleus.