Determination of genetic diversity in MHC gene region between commercial chicken types and indigenous chicken breeds in turkey

In this study, the region which belongs to 30 Denizli, 30 Gerze, 10 Lohmann?LSL white egg layer, 10 Brown nick layer and 10 Broiler chicken, was investigated for TAP 1 gene region from exon 6 till exon 7, for TAP 2 gene region from exon 4 till exon 6 and for Tapasin gene region from exon 5 till exon 6. In all strains that were examined, TAP 1, TAP 2 and Tapasin lengths were determined respectively 431 bp, 399 bp and 448 bp. However, In the sequence analyses of Tapasin gene region, in base sequences, the exact result could not be obtained. In TAP 1 gene region, polymorphic regions were identified as below numbers; In Denizli 15, Gerze 7, Brown egg layer 8, white egg layer 8 and broilers 10 and in TAP 2 gene region in Denizli 16, Gerze 14, Brown Egg Layer 5, White Egg Layer 9 and Broilers 13.In all groups that were investigated, in population the highest value of genetic distance was recorded in Denizli race, as stated respectively for TAP 1 region 0,0087, for TAP 2 region 0,0175, for TAP 1 + TAP 2 region 0,0123. Intra population the lowest value of genetic distance for TAP 1 region was in Gerze race as with 0,0056, and for TAP 2 and TAP 1 + TAP 2 regions was found in Brown egg layer respectively 0,0048 and 0,0063. These results shows that for TAP 1 gen region Gerze race, and for TAP 2, TAP 1 + TAP 2 gen regions, Brown egg layers have more homogeneous structure than other races and this suggest that they were brought up in a narrow region and they can be related closely, in TAP 1, TAP 2, TAP 1 + TAP 2 gen regions Denizli race have more heterogenic structure than other races and this suggest that near relation probability for these samples in intrapopulation is very low.In TAP 1 gene region, genetic distance values between populations were (0,0069 ± 0,0025) the lowest between Gerze and broiler, however the highest was (0,0137 ± 0,0039) estimated between Denizli and broiler. In TAP 2 gene rejion,the lowest values of genetic distance was estimated between Brown egg layer and broiler population (0,0132 ± 0,0039), the highest value of genetic distance was estimated between Denizli and White Egg Layer population (0,0248 ± 0,0062). In TAP 1 + TAP 2 gen region, the lowest values of genetic distance between populations estimated between Gerze and Broiler (0,0108 ± 0,0023 ), and the highest value estimated between Denizli and White Egg Layer populations (0,0175 ± 0,0033).According to the İnterior-Branch Test and Bootstrap Test phylogenetic trees that were crossed by using Neighbor- Joining tree method, two big cluster were visible, Gerze race and broilers are one of these big cluster, and the other big cluster is constituted with Denizli race and egg layer chickens. According to the Tajima Neutrality Test results, values which are belong to the TAP 1, TAP 2, TAP 1 + TAP 2 gen regions are found respectively, for ? value 0,0097, 0,0183, 0,0136; for ? value 0,0065, 0,0106, 0,0084; for D value 1,3913, 2,1317, 1,9558.The values of genetic distance for Gerze and Denizli races and their phylogenetic tree results suggest that these two races are probably different races and results connote the possibility of having their origins from different regions .The present study is aimed to identify polymorphism in TAP 1, TAP 2, Tapasin gene regions of MHC region in Denizli and Gerze indigenous chicken races, and also aimed to demonstrate the differences of MHC gene region between indigenous chicken races and commercial chicken species. Moreover, this study can be an initial guide for the future genetic studies and investigations that will be in Mhc gene region of indigenous chicken races. Results provide structural informations about chicken TAP genes and their polymorphism levelsKey Words: MHC, Polymorphism, TAP, Tapasin, Chicken, Denizli race, Gerze race .