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Functional chimeric genes in ciliates: An instructive case from Euplotes raikovi
Francesca Ricci1, Pierangelo Luporini1, Claudio Alimenti1
1Laboratory of Eukaryotic Microbiology and Animal Biology, School of Biosciences and Veterinary Medicine, University of Camerino, Camerino 62032, Italy.
Gene
|September 30, 2020
Summary
Ciliate sexual reproduction involves creating new genes from DNA fragments. Researchers found a chimeric gene (mac-er-1*) in Euplotes raikovi, demonstrating this error-prone process increases genetic diversity.
Area of Science:
- Molecular Biology
- Genetics
- Epigenetics
Background:
- Ciliate sexual reproduction involves the loss and de novo assembly of somatic macronuclear genes.
- This assembly process starts from germline micronuclear DNA sequences called Macronuclear Destined Sequences (MDS).
- Errors in RNA-mediated epigenetic mechanisms during MDS assembly can lead to chimeric gene formation.
Purpose of the Study:
- To investigate the chimeric structure of a specific gene family involved in pheromone synthesis in Euplotes raikovi.
- To characterize the mac-er-1* gene, previously identified as encoding pheromone molecules.
- To provide evidence for the role of somatic MDS recombination in generating genetic variability in ciliates.
Main Methods:
- Analysis of the gene family controlling pheromone synthesis in Euplotes raikovi.
- Identification and characterization of the chimeric structure of the mac-er-1* macronuclear gene.
- Comparison of the mac-er-1* gene's 5' region with known MDS and germline sequences.
Main Results:
- The mac-er-1* gene, encoding soluble and membrane-bound pheromones, exhibits a chimeric structure.
- Its 5' region is a 360-bp sequence unrelated to the pheromone gene, derived from an MDS.
- This MDS is also destined for a separate 2417-bp gene encoding an unknown protein.
Conclusions:
- Functional chimeric genes can arise from non-programmed somatic MDS recombination in ciliates.
- This mechanism contributes to increasing species genetic variability independently of germline genome reshuffling.
- The mac-er-1* gene characterization supports the significance of chimeric gene formation in ciliate evolution.
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