Genetic diversity in a Brazilian bovine herd based on four microsatellite loci

Abstract

Microsatellites or short tandem repeats (STRs), DNA markers relatively abundant in the genome, have a high degree of polymorphism and therefore great potential for characterizing populations. The present study estimates genetic variability in a set of four microsatellites (BMS3013, BMS3004, HEL10 and TGLA122) in a Brazilian hybrid bovine breed (5/8 Aberdeen Angus x 3/8 Nelore). The objectives were to determine the effect of crossbreeding and selection in these animals' genetic diversity as well as to discover the herd's genetic relationship with that of other breeds. Low diversity was verified in BMS3013 and high diversity was detected in BMS3004, HEL10 and TGLA122. Two alleles in TGLA122 are described here for the first time (TGLA122*155 and TGLA122*163). These genes are possibly characteristics of Zebu animals since they have not been found in other taurine samples so far investigated. Low interpopulational diversity was observed among taurine cattle populations, and clusters obtained on TGLA122 phylogenetic trees agreed with the bovine herd's geographic origin. Therefore, despite TGLA122's high polymorphism and high levels of intrapopulational diversity, the system engenders consistent bovine phylogenies. We detected an intriguingly high similarity between Brangus Ibagé and Red Angus since the former is a hybrid having 3/8 of Nelore genes. Either these animals' environment or genetic selective practices applied to the breed probably favor the Angus genotype.<br>Microssatélites ou repetições curtas em tandem (STRs) são marcadores moleculares de relativa abundância no genoma e apresentam alto grau de polimorfismo, constituindo-se numa excelente ferramenta para a caracterização das populações. Este trabalho estimou a variabilidade genética de quatro microssatélites (BMS3013, BMS3004, HEL10 e TGLA122) em um rebanho híbrido de bovinos brasileiros (5/8 Aberdeen Angus x 3/8 Nelore), com os objetivos de verificar o efeito do cruzamento e das práticas seletivas na composição genética do rebanho e avaliar as relações genéticas destes animais com outras populações bovinas mundiais. Verificou-se uma baixa diversidade no BMS3013, mas alta variabilidade nos STRs BMS3004, HEL10 e TGLA122. No TGLA122 dois alelos novos estão sendo descritos pela primeira vez (TGLA122*155 e TGLA122*163). É possível que esses genes sejam característicos de Zebu, uma vez que não ocorrem em outras raças taurinas investigadas até o momento. Uma baixa diversidade interpopulacional foi observada entre as populações taurinas, e os agrupamentos obtidos nas filogenias baseadas no TGLA122 foram coerentes com a origem geográfica dos rebanhos. Assim, apesar do TGLA122 ser altamente polimórfico e apresentar altos níveis de diversidade intrapopulacional, ele é um marcador muito eficiente para a construção de filogenias bovinas. Detectou-se uma grande similaridade entre Brangus Ibagé e Red Angus, apesar do Brangus Ibagé ser um rebanho híbrido com 3/8 de genes Nelore. É possível que o ambiente onde esses animais vivem ou as práticas seletivas aplicadas ao reba...

Effects of polymorphisms of LHR and FSHR genes on sexual precocity in a Bos taurus x Bos indicusbeef composite population

“…On the other hand, Almeida et al (2000) reported important effects of two markers, the LEPSau3AI (RFLP) and the IDVGA-51 (short tandem repeat), for the leptine gene on both the reproductive and productive characteristics, respectively, as time interval between births (IP) and weight at the first birth (PPP) in 5/8 Aberdeen Angus x 3/8 Nellore females. The increase in IP for at least two months of age has been observed by the effect of the two markers, while PPP has been shown to be positively influenced by the LEPSau3AI up to 27 kg.…”

Candidate genes related to reproductive traits of Hereford and Braford bulls

“…In addition, the LHR and FSHR markers are located in exon 11 and exon 10 on chromosome 11, respectively (LUSSIER et al, 1995;MARSON et al, 2005), and may play a role in silencing or changing its protein amino acid composition. Indeed, molecular markers have been widely used to investigate genes that code for important traits in animal production (ALMEIDA et al, 2000;MACHADO et al, 2003).…”

“…Moreover, Silveira et al (2013) observed better reproductive performance in animals carrying the short IDVGA-51 allele (173-177 bp) than in animals carrying a longer allele (IDVGA-51*181), which had been classified as subfertile because they did not calve in the previous reproductive season and remained open after two breeding seasons. Cows carrying the IDVGA-51*181 allele showed a higher expression of LEP in the subcutaneous tissue, which is important in determining the nutritional effect on the animal's reproductive performance (ALMEIDA et al, 2000(ALMEIDA et al, , 2003. Indeed, the LEP hormone serves as a metabolic signal of energy balance within the neuroendocrine system, and LEP mRNA is present in bull spermatozoa and plays an important role with physiological effects (NIKBAKHT et al, 2010).…”

“…HEL5 and AFZ1, located on BTA21 of the insulin growth factor I receptor (IGF-IR) gene, are markers showing an association with greater calving interval (BARENDSE et al, 1997;OLIVEIRA et al, 2005). The leptin (LEP) gene is directly related to the presence of alleles for IDVGA-51 located on the BTA4 that indicate an increasing calving interval in cows (ALMEIDA et al, 2000). The genetic diversity in crossbred beef cows demonstrates that ILSTS002 and BMS3004 are associated with the luteinizing hormone-β (LHβ) gene on BTA18 that is associated with reproductive performance (SILVEIRA et al, 2013).…”

Seleção tradicional e associada a marcadores moleculares na avaliação genética animal

“…Os marcadores moleculares têm sido muito utilizados também na caracterização de populações, de acordo com Kuhnlein et al (1989), Gilbert et al (1991), Mannen et al (1993), Vierling et al (1994), Yang et al (1999) e Almeida et al (2000).…”