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Karimi, Karim,Koshkoiyeh, Ali Esmailizadeh,Gondro, Cedric Korean Society of Animal Sciences and Technology 2015 한국축산학회지 Vol.57 No.12
Background: Knowledge of linkage disequilibrium (LD) levels among different populations can be used to detect genetic diversity and to investigate the historical changes in population sizes. Availability of large numbers of SNP through new sequencing technologies has provided opportunities for extensive researches in quantifying LD patterns in cattle breeds. The aim of this study was to compare the extent of linkage disequilibrium among Iranian cattle breeds using high density SNP genotyping data. Results: A total of 70 samples, representing seven Iranian indigenous cattle breeds, were genotyped for 777962 SNPs. The average values of LD based on the $r^2$ criterion were computed by grouping all syntenic SNP pairwises for intermarker distances from 0 Kb up to 1 Mb using three distance sets. Average $r^2$ above 0.3 was observed at distances less than 30 Kb for Sistani and Kermani, 20 Kb for Najdi, Taleshi, Kurdi and Sarabi, and 10 Kb for Mazandarani. The LD levels were considerably different among the Iranian cattle breeds and the difference in LD extent was more detectable between the studied breeds at longer distances. Lower level of LD was observed for Mazandarani breed as compared to other breeds indicating larger ancestral population size in this breed. Kermani breed continued to have more slowly LD decay than all of the other breeds after 3 Kb distances. More slowly LD decay was observed in Kurdi and Sarabi breeds at larger distances (>100 Kb) showing that population decline has been more intense in more recent generations for these populations. Conclusions: A wide genetic diversity and different historical background were well reflected in the LD levels among Iranian cattle breeds. More LD fluctuation was observed in the shorter distances (less than 10 Kb) in different cattle populations. Despite of the sample size effects, High LD levels found in this study were in accordance with the presence of inbreeding and population decline in Iranian cattle breeds.
Hasan Moradian,Ali Esmailizadeh Koshkoiyeh,Mohammadreza Mohammadabadi,Masood Asadi Fozi 한국유전학회 2020 Genes & Genomics Vol.42 No.2
Background The identification of genomic regions under selection can potentially permit a better understanding of the biology of the specific phenotypes which are useful for the development of tools designed to increase selection efficiency. Objective The aim of this study was to detect any traces of recent selection signatures as well as to identify corresponding genes and QTLs underlying these selection signatures in Sarabi cattle. Methods Samples from 20 animals were genotyped for 777,962 SNPs across the genome using the Illumina BovineHD BeadChip. Selection signatures analysis was performed using the integrated haplotype score (iHS) methodology. Results A total of eight significant regions (P < 0.0001) of possible recent selection signatures were detected on BTA14 and BTA17. In addition, nine genes were identified in regions harboring selection signatures, such as KCNQ3, HHLA1, OC90, EFR3A, ADCY8, ASAP1, TMEM132B, and TMEM132C. Study of the reported QTLs in these regions of the bovine genome has showed that they are associated with important traits such as milk, reproduction and production traits. Conclusion The results revealed multiple genomic regions as well as multiple new genes under positive selection on BTA14 and BTA17. Moreover, candidate selected regions that overlap with QTL reported in the cattle QTL database provided additional evidence for the significance of the detected regions under selection. This study provides a foundation for detailed analysis of the identified putative selection signatures in the cattle genome particularly of the indigenous and locally-developed cattle breeds and provides an avenue for a well-structured breed improvement.
( Karim Karimi ),( Ali Esmailizadeh Koshkoiyeh ),( Cedric Gondro ) 한국동물자원과학회(구 한국축산학회) 2015 한국축산학회지 Vol.57 No.47
Background: Knowledge of linkage disequilibrium (LD) levels among different populations can be used to detect genetic diversity and to investigate the historical changes in population sizes. Availability of large numbers of SNP through new sequencing technologies has provided opportunities for extensive researches in quantifying LD patterns in cattle breeds. The aim of this study was to compare the extent of linkage disequilibrium among Iranian cattle breeds using high density SNP genotyping data. Results: A total of 70 samples, representing seven Iranian indigenous cattle breeds, were genotyped for 777962 SNPs.The average values of LD based on the r2 criterion were computed by grouping all syntenic SNP pairwises for intermarkerdistances from 0 Kb up to 1 Mb using three distance sets. Average r2 above 0.3 was observed at distances less than 30 Kb for Sistani and Kermani, 20 Kb for Najdi, Taleshi, Kurdi and Sarabi, and 10 Kb for Mazandarani. The LD levels were considerably different among the Iranian cattle breeds and the difference in LD extent was more detectable between the studied breeds at longer distances. Lower level of LD was observed for Mazandarani breed as compared to other breeds indicating larger ancestral population size in this breed. Kermani breed continued to have more slowly LD decay than all of the other breeds after 3 Kb distances. More slowly LD decay was observed in Kurdi and Sarabi breeds at larger distances (>100 Kb) showing that population decline has been more intense in more recent generations for these populations. Conclusions: A wide genetic diversity and different historical background were well reflected in the LD levels among Iranian cattle breeds. More LD fluctuation was observed in the shorter distances (less than 10 Kb) in different cattle populations. Despite of the sample size effects, High LD levels found in this study were in accordance with the presence of inbreeding and population decline in Iranian cattle breeds.