Caracterización genética de cuatro poblaciones de ovinos criollos de Argentina / Genetic characterization of four populations of Argentinian creole sheep

Los ovinos criollos son los fundadores de la ganadería ovina en la Argentina y han contribuido de manera sostenida al desarrollo económico, social y cultural de algunas regiones del país. A pesar de ello, es un recurso zoogenético escasamente valorizado y por ende poco estudiado. En orden de caracterizar genéticamente a los ovinos criollos argentinos, se tomaron muestras de ADN de cuatro poblaciones representativas localizadas en las provincias de Buenos Aires, Corrientes, Santiago del Estero y Salta. Estas majadas se seleccionaron por ser grupos conservados, que presentan las características fenotípicas de la raza y no registran la introducción de animales de otras razas en el sistema de reproducción. Un total de 30 marcadores microsatélites y la región D-loop del ADN mitocondrial fueron analizados. El análisis de los microsatélites permitió evidenciar una alta diversidad genética intrapoblacional (Ho= 0,676; He= 0,685; PIC= 0,713). Dicha variabilidad es explicada por diferencias entre los patrones moleculares de los individuos estudiados que pueden clasificarse en 3 grupos de poblaciones significativamente diferentes: BA, SA, SE+CO. Dado que dichas poblaciones explican muy poco de la variabilidad total (7,6%), ellas deberían considerarse perteneciente a una misma raza. El análisis del D-loop mitocondrial demostró que los individuos analizados están relacionados con el haplogrupo asiático, el cual está ampliamente distribuido en las razas españolas que son las antecesoras de la raza criolla argentina. Los resultados obtenidos en este trabajo proveerán información para establecer criterios de manejo de este recurso genético de Argentina con el fin de implementar planes de conservación, recuperación y/o mejora de los programas.

Creole sheep are the founders of sheep farming in Argentina and have contributed in a sustained way to the economic, social and cultural development of some regions of this country. However, it is a scarcely valorised and poorly studied genetic resource. In order to genetically characterize the Argentinian Creole sheep, DNA samples were taken from four representative populations located in the provinces of Buenos Aires, Corrientes, Santiago del Estero and Salta. These flocks were selected because they are considered to be conserved groups, they have the phenotypic characteristics of the creole breed and there are no records about the introduction of animals of other breeds into those systems. A total of 30 microsatellites and the D-loop region of mitochondrial DNA were analysed. Microsatellite analysis showed high level of genetic diversity within populations (Ho= 0.676; He= 0.685; PIC= 0.713). This variability is explained by differences between molecular patterns of the studied individuals, which can be classified into three significantly different population groups: BA, SA, SE+CO. Since these populations explain very little of the total variability (7.6%), it can be considered that they belong to a same race. The analysis of the mitochondrial D-loop showed that Argentinian Creole sheep have haplotypes belonging to the Asian haplogroup, which is widely distributed in the Spanish breeds, which are considered to be their ancestors. The results obtained in the present study will provide information to develop management criteria for this genetic resource in Argentina, in order to implement their conservation, recovery and/or to develop breeding programs.

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

Genetic variability and population structure in loci related to milk production traits in native Argentine Creole and commercial Argentine Holstein cattle

Muitas raças de gado foram submetidas a alta pressäo de seleçäo para caracteres de produçäo. Conseqüentemente, a estrutura genética e a distribuiçäo alélica da populaçäo poderiam diferir em raças sob alta pressäo de seleçäo, quando comparadas a raças näo selecionadas. Foi feita a análise das freqüências dos genes de K-caseína, aS1-caseína e prolactina em rebanhos de gado Creole argentino (AC) e Holstein argentino (AH). Os valores de FST calculados mediram o grau de diferenciaçäo genética de subpopulaçöes, dependendo de variaçöes na freqüência dos genes. A raça AC apresentou variaçäo consideravelmente maior entre os rebanhos nos loci de aS1-caseína e K-caseína. Estratégias de conservaçäo devem considerar a populaçäo inteira de AC de forma a manter a variabilidade genética encontrada nesta raça nativa.