Analysis of genetic diversity and population structure in Argentine and Bolivian Creole cattle using five loci related to milk production

Data from five protein-coding loci related to dairy production were used to study the genetic diversity and population structure of Argentine and Bolivian Creole cattle breeds. Genomic DNA was extracted from blood samples of six Creole cattle breeds: Argentine (n = 230), Patagonian (n = 25); "Saavedreño" (n = 140), "Chaqueño Boliviano" (n = 30), "Yacumeño" (n = 27), and "Chusco" (n = 11). kappa-casein, beta-lactoglobulin, growth hormone and prolactin were measured by PCR-RFLP, while alphaS1-casein was typed by PCR-ASO. The results are discussed, focusing on: historical origin, recent differentiation and selection events, Zebu gene introgression, and population structure. This work shows that: (i) For the studied genes, the observed gene frequency profiles of Argentine and Bolivian Creole cattle breeds were close to the data reported for Iberian breeds and for other South-American Creole cattle breeds which are historically related; (ii) although Zebu gene introgression has been reported at the studied loci, these breeds seem to be far from the Zebu gene frequency profiles; and (iii) the Argentine and Bolivian Creole cattle showed significant levels of subdivision, but each population has maintained its degree of genetic variability

Greater genetic variability in Argentine Creole than in Thoroughbred horses based onserum protein polymorphisms

Genetic polymorphism was analyzed for five blood proteins: albumin - Al, esterase - Es, a1B-glycoprotein - Xk, transferrin - Tf and hemoglobin - Hb in 200 Thoroughbred (TB) and 124 Argentine Creole (AC) horses. Of the five systems examined, Tf and Hb were not in Hardy-Weinberg equilibrium in either breed and Es was not in equilibrium in the Creole breed. Genetic variability, estimated as average heterozygosity, was higher in AC (H = 0.585 ± 0.131) than in TB (H = 0.353 ± 0.065). The genetic differentiation between these two populations (FST) was 0.109. Thus, of the total genetic differences between breeds, the proportion of genetic variation attributable to breed differences was about 10%; the remaining 90% was due to individual variation within breeds. The high degree of genetic variability seen in Argentine Creole horses could be a consequence of natural selection. Selection of TB through the centuries has most likely modified the gene pool of the ancestral population, with a consequent reduction in variability at certain loci. Probably, different mechanisms exist for maintaining polymorphism at these loci in TB and in AC horses. Heterozygosity may have played a fundamental role in adaptation.

Mitochondrial variability in the D-loop of four equine breeds shown by PCR-SSCP analysis

A fragment of 466 base pairs from a highly variable peripheral region of the mitochondrial D-loop of horses was amplified and analyzed by single stranded conformational polymorphism (SSCP). Fourteen distinct SSCP variants were detected in 100 horses belonging to four breeds (Arabian, ARB; Thoroughbred, TB; Argentinian Creole, ARC; and Peruvian Paso from Argentina, PPA). Each breed showed four to eight SSCP variants, many of which were shared between two or three of the studied breeds. Arabian horses were the most variable (eigth variants), with three variants unique to the breed. PPA and ARC showed two and one characteristic SSCP variants, respectively, while TB shared all its variants with at least one of the other breeds. An analysis based on the presence/absence of the variants revealed a closer relationship between PPA and TB, which was not completely unexpected considering the mixed ancestry of the PPA mares. The results also confirm the efficiency of SSCP to detect variability in horse mitochondrial DNA