Evidence for Gene Duplication and Allelic Codominance (not Hierarchical Dominance) at the Mating‐Type Locus of the Ciliate, Euplotes crassus. (4th August 2014)

• Record Type: Journal Article
• Authors: Vallesi, Adriana; Alimenti, Claudio; Federici, Sergio; Di Giuseppe, Graziano; Dini, Fernando; Guella, Graziano; Luporini, Pierangelo
• Is Part Of: Journal of eukaryotic microbiology. Volume 61:Number 6(2014:Nov./Dec.)
• Page Start: 620
• Page End: 629
• Publication Date: 2014-08-04
• Subjects: Protista -- Periodicals; Eukaryotic cells -- Periodicals; Microbiology -- Periodicals; 579.05
• DOI: 10.1111/jeu.12140
• Languages: English
• ISSNs: 1066-5234

Abstract

<abstract abstract-type="main" id="jeu12140-abs-0001"> <title>Abstract</title> <p>The high‐multiple mating system of <italic>Euplotes crassus</italic> is known to be controlled by multiple alleles segregating at a single locus and manifesting relationships of hierarchical dominance, so that heterozygous cells would produce a single mating‐type substance (pheromone). In strain L‐2D, now known to be homozygous at the mating‐type locus, we previously identified two pheromones (E<italic>c</italic>‐α and E<italic>c</italic>‐1) characterized by significant variations in their amino acid sequences and structure of their macronuclear coding genes. In this study, pheromones and macronuclear coding genes have been analyzed in strain POR‐73 characterized by a heterozygous genotype and strong mating compatibility with L‐2D strain. It was found that POR‐73 cells contain three distinct pheromone coding genes and, accordingly, secrete three distinct pheromones. One pheromone revealed structural identity in amino acid sequence and macronuclear coding gene to the E<italic>c</italic>‐α pheromone of L‐2D cells. The other two pheromones were shown to be new and were designated E<italic>c</italic>‐2 and E<italic>c</italic>‐3 to denote their structural homology with the E<italic>c</italic>‐1 pheromone of L‐2D cells. We interpreted these results as evidence of a phenomenon of gene duplication at the <italic>E. crassus</italic> mating‐type locus, and lack of hierarchical dominance in the expression of the macronuclear pheromone genes in cells with heterozygous genotypes.</p> </abstract>