The high-multiple (“open”) systems of mating types (MT) that control self/non-self recognition in the most recently evolved complex of Euplotes species are traditionally considered to be genetically determined by series of single-locus alleles designated as mat-1, mat-2, mat-3, and so forth. These genes are inherited and expressed accordingly to a Mendelian mechanism of serial dominance (i.e., mat-1 > mat-2 > mat-3 and so forth). Therefore, the heterozygous condition (e. g., mat-1/mat-2) would mimic the corresponding dominant condition (i. e., mat-1/mat-1), both gene combinations expressing the same phenotype MT-I due to the production of only one chemical signal (pheromone) specified by the dominant gene mat-1. Working on a paradigmatic modern species, E. crassus, we first characterized the amino acid sequence of a pheromone (designated as Ec-ph1) purified from the culture filtrates of the strain L2D. Based on the knowledge of this sequence, we synthesized oligos for PCR-cloning the Ec-ph1 gene from the strain L2D, as well as other pheromone genes from other E. crassus strains. We obtained evidence that the Ec-ph1 gene: (i) coexists in the strain L2D with a second pheromone gene (Ec-ph2) which is structurally divergent from the Ec-ph1 gene and equally expressed; (ii) is present and co-expressed also in other E. crassus strains in combination with other homologous (allelic) pheromone genes (Ec-ph3, Ec-ph4, and so forth). These observations thus imply that in the modern species of Euplotes, as is the case in the ancient ones, the multiple series of mat genes are regulated by relationships of co-dominance rather than of serial dominance. Crucial insights to understand the functional differences between the two models await a definitive characterization of the expression and activity of the Ec-ph1 pheromone gene in multiple E. crassus strains.
New insight into the genetic basis of the high-multiple mating type systems of the modern species of the ciliate Euplotes. REPORT of the XIth scientific meeting of the Italian Association of Developmental and Comparative Immunobiology (IADCI), Modena
VALLESI, Adriana;ALIMENTI, Claudio;LUPORINI, Pierangelo
2010-01-01
Abstract
The high-multiple (“open”) systems of mating types (MT) that control self/non-self recognition in the most recently evolved complex of Euplotes species are traditionally considered to be genetically determined by series of single-locus alleles designated as mat-1, mat-2, mat-3, and so forth. These genes are inherited and expressed accordingly to a Mendelian mechanism of serial dominance (i.e., mat-1 > mat-2 > mat-3 and so forth). Therefore, the heterozygous condition (e. g., mat-1/mat-2) would mimic the corresponding dominant condition (i. e., mat-1/mat-1), both gene combinations expressing the same phenotype MT-I due to the production of only one chemical signal (pheromone) specified by the dominant gene mat-1. Working on a paradigmatic modern species, E. crassus, we first characterized the amino acid sequence of a pheromone (designated as Ec-ph1) purified from the culture filtrates of the strain L2D. Based on the knowledge of this sequence, we synthesized oligos for PCR-cloning the Ec-ph1 gene from the strain L2D, as well as other pheromone genes from other E. crassus strains. We obtained evidence that the Ec-ph1 gene: (i) coexists in the strain L2D with a second pheromone gene (Ec-ph2) which is structurally divergent from the Ec-ph1 gene and equally expressed; (ii) is present and co-expressed also in other E. crassus strains in combination with other homologous (allelic) pheromone genes (Ec-ph3, Ec-ph4, and so forth). These observations thus imply that in the modern species of Euplotes, as is the case in the ancient ones, the multiple series of mat genes are regulated by relationships of co-dominance rather than of serial dominance. Crucial insights to understand the functional differences between the two models await a definitive characterization of the expression and activity of the Ec-ph1 pheromone gene in multiple E. crassus strains.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
