Identification of interbreed chicken chimeras and prospects of use

Purpose: Chimeric birds are of interest in breeding and genetic engineering. Identification of such birds was initially phenotypic, for which breeds with contrasting plumage color were used. However, this method is imperfect, and the purpose of this work was to develop an optimal method for identifying interbreed chimeras of birds. Materials and methods. Based on the Central Clinical Hospital of the Breeding Community "Genetic Collection of Rare and Endangered Chicken Breeds of the All-Russian Research Institute of Chicken Breeding and Geography of the Russian Academy of Sciences", 4 breeds were selected: Poltava Clay, Sussex, Pale Brahma, and Light Brahma as donors and recipients. These breeds were selected based on genetic differences: Pale Brahma and Poltava Clay have the s+ allele of the Silver gene, Light Brahma and Sussex have the S allele of the same gene. The difference between the two alleles is ensured by a single nucleotide substitution C\T, which significantly simplifies identification. Chimeras were obtained by transplanting donor cells into recipient embryos. Among the obtained birds, some demonstrated a mosaic phenotype with the manifestation of the donor breed traits, while others had the phenotype of the recipient breed. After slaughtering the birds, tissue samples were taken from the ovaries, testes and liver. DNA was isolated from them using the standard phenol-detergent method. DNA samples were examined by amplification using allele-specific probes at the SLC45A2 (Silver) gene locus located on the Z chromosome (alleles S and s+).
The genotyping results showed that among the analyzed DNA samples from 12 experimental birds, 5 were found to have both donor and recipient genotypes. At the same time, in 4 chimeras, the donor genotype was detected in the reproductive organs, i.e. these chimeras are sexual and could pass on the donor genotype to their offspring.

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