Polymorphism of the pre-gga-miR-24* Gene and White-Creamy-Brown Coloration of Chicken Eggs

Abstract

Two pigments are mainly responsible for the eggshell color of poultry eggs: protoporphyrin IX and biliverdin. It is considered that protoporphyrin IX is responsible for the brown color of eggshells, while biliverdin is associated with the blue-green color of eggs. The molecular biology of avian eggshell pigmentation is poorly studied. However, several genes have been significantly associated with the brownness or whiteness of chicken eggshells. It is already well known that small noncoding microRNAs are involved in the regulation of gene expression. This study focuses on the possible involvement of microRNAs (namely gga-miR-24-3p) in the regulation of the expression of the CPOX gene, which is associated with the brown color of the eggshell. The gene polymorphism of this microRNA (pre-gga-miR-24*) is studied in this work. The question of a possible association of the pre-gga-miR-24* gene with the brown color of eggs is being considered. We used 20 eggs of four breeds: Italian Partridge, Russian White, Pushkin, and Rhode Island Red. As a result of the study, a polymorphism of the pre-gga-miR-24* gene was identified, and its six alleles (a – f) were found, which are present at two loci: on chromosome Z and 30. It was suggested that these alleles may be involved in the control of the white-creamy(beige)-brown color gamut of chicken eggs. It is also assumed that the a allele is recessive and is associated with the white color of eggs in the homozygous state. At the same time, different combinations of six a – f alleles in the heterozygous state, at least in one locus, can be associated with different degrees of creamy(beige)-brown coloration of chicken eggs. Moreover, each of the five b – f alleles, except for the a allele, in the homozygous state can also be associated with its creamy(beige)-brown tint in the eggshell color gamut.