RNA-Dependent Genome Processing During Nuclear Differentiation: The Model Systems of Stichotrichous Ciliates

Abstract

We introduce ciliated protozoa, and more specifically the stichotrichous ciliates Oxytricha and Stylonychia, as biological model systems for the analysis of programmed DNA-reorganization processes during nuclear differentiation. These include DNA excision, DNA elimination, reordering of gene segments and specific gene amplification. We show that small nuclear RNAs specify DNA sequences to be excised or retained, but also discuss the need for a RNA template molecule derived from the parental nucleus for these processes. This RNA template guides reordering of gene segments to become functional genes and determines gene copy number in the differentiated nucleus. Since the template is derived from the parental macronucleus, gene reordering and DNA amplification are inherited in a non-Mendelian epigenetic manner.

KEYWORDS::

• ciliated protozoa
• gene amplification
• gene processing
• nuclear differentiation

Financial & competing interests disclosure

Work in the authors‘ laboratories are supported by the Deutsche Forschungsgemeinschaft, the European Research Council and COST Action (BM1102). The authors have no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript apart from those disclosed.

No writing assistance was utilized in the production of this manuscript.

Additional information

Funding

Work in the authors‘ laboratories are supported by the Deutsche Forschungsgemeinschaft, the European Research Council and COST Action (BM1102). The authors have no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript apart from those disclosed. No writing assistance was utilized in the production of this manuscript.