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Articles by S. Ommeh
Total Records ( 2 ) for S. Ommeh
  S. Ommeh , L.N. Jin , H. Eding , F.C. Muchadeyi , S. Sulandari , M.S.A. Zein , G. Danbaro , C.E. Wani , S.G. Zhao , Q.H. Nie , X.Q. Zhang , M. Ndila , R. Preisinger , G.H. Chen , I.A. Yousif , K.-N. Heo , S.J. Oh , M. Tapio , D. Masiga , O. Hanotte , H. Jianlin and S. Weigend
  An A/G Single Nucleotide Polymorphism (SNP) at position 1,892 of the Mx gene coding sequence has been linked to susceptibility/resistance to avian viral infection in vitro. Using PCR-RFLP and sequencing methods, 1,946 samples from 109 populations from Asia, Africa and Europe; grouped as indigenous village, commercial, fancy chicken as well as wild junglefowl were genotyped for the polymorphism. Allele and genotype frequencies were calculated. Only the G allele was present in Ceylon junglefowl Gallus lafayetti. Using the wild red junglefowl G. gallus population as reference, we assessed if the A/G alleles and genotypes frequencies have been affected by the breeding history and the geographic dispersion of domestic chicken. Within group variation was high but overall there were no significant variation in distribution of alleles and genotypes frequencies between the red junglefowl and indigenous village chickens (p>0.1946), with the exception of the East Asian group (p<0.0001). However, allele and genotype frequencies were significantly different between the red junglefowl and the commercial or fancy groups (p<0.0001). A small but significant negative correlation (r = - 0.166, p<0.0003) was observed between allelic and geographic distance matrices amongst indigenous village chicken populations. Human selection and genetic drift are likely the main factors having shaped today’s observed allele and genotype frequencies in commercial and fancy breeds. In indigenous village chicken and red junglefowl, we propose that both A and G alleles have been maintained by natural selection for disease resistance through a balancing selection mechanism.
  T.C. Keambou , B.A. Hako , S. Ommeh , C. Bembide , E.P. Ngono , Y. Manjeli , F. Wamonje , Nzuki , B. Wanjala , M. Wamalwa , C.Y. Cho , R.A. Skilton and A. Djikeng
  Cameroon has a wide range of agro-ecological zones, having indigenous chicken populations which are thought to be adapted and diversified. Genetic diversity of the Cameroon chicken populations from agro-ecological zones I, II, III and IV was assessed using 25 microsatellite markers. A total of 314 chickens were genotyped, revealing 226 distinct alleles and 24 private alleles (10.62%). The mean polymorphic information content was 0.57. The average observed, expected and unbiased frequencies of heterozygote were 0.60, 0.62 and 0.65 respectively, with the mean Shannon index of 1.21. The global inbreeding coefficient among population was 0.13. Inbreeding coefficient varied significantly with 4.27% variation observed among ecotypes. Within ecotypes the highest diversity was observed in the Bafang-Bakou population having 7.92±4.22 alleles per locus, 168.80±4.73 gene copies, 9 private alleles and 0.68±0.02 expected heterozigosity. However the same region displayed the highest inbreeding coefficient (0.13). In all the populations, 67% of the loci did not deviate significantly from the Hardy-Weinberg. The neighbor-joining tree, UPGMA cladogram as well as the Evanno’s population structure parameters revealed existence of 3 clusters in Cameroon chicken populations. The current study confirmed usefulness of microsatellites for studying genetic variation of the Cameroonian indigenous chicken. They demonstrate information on genetic variability of Cameroon local chicken populations, offer steps towards rational decision making prior to genetic improvement and conservation programs, without compromising the existence of each unique genotype.
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