SNPs rs471462296, rs456245081 and rs438495570 in the 5’UTR region of DGAT1 gene in Nelore

SNPs rs471462296, rs456245081 e rs438495570 na região 5'UTR do gene DGAT1 em Nelore

RESUMO

O objetivo desta pesquisa foi avaliar os SNPs rs471462296, rs456245081 e rs438495570 do gene DGAT1 em bovinos Nelore. Foram analisados 109 bovinos. A extração do DNA genômico foi realizada do sangue dos animais, usando-se o kit Ilustra Blood Genomic Prep Mini Spin® (GE Healthcare, UK). A concentração e o grau de pureza do DNA foram determinados por meio de espectrofotômetro (Nanodrop - Thermo Fisher Scientifc, USA). A genotipagem dos SNPs ocorreu mediante o emprego do ensaio Taqman® (Applied Biosystems, USA). Na análise genômica, não foram encontradas alterações nas frequências alélicas e genotípicas (P≥0,05) para os SNPs testados. Dessa forma, a região 5’UTR analisada apresentou-se monomórfica e a variação de SNPs não foi observada, o que limita seu uso como marcadores moleculares para o gene DGAT1 em Nelore.

Palavras-chave:
bovino; fenótipo; genótipo; seleção

Keywords:
bovine; phenotype; genotype; selection

Palavras-chave:
bovino; fenótipo; genótipo; seleção

In Bos taurus, the diacylglycerol O-acyltransferase (DGAT1) gene is about 8.6Kb in length, comprise of 17 exons, spanning over 121.8bp, and it is located on BTA14 (Kaupe et al., 2004. DGAT1 has been associated with phenotypes of economic interest in cattle. The gene has been traditionally known as a positional and functional marker for both dairy production and increased fat content in milk (Tabaran et al., 2015). DGAT1 encodes for an enzyme, containing 489 amino acids, responsible for catalyzing the final step of triglycerides synthesis covalently linking diacylglycerol to fatty acyl-CoA substrates. This gene is expressed in many tissues, with the highest levels in the intestine, testis, and mammary glands, especially in adipose and epithelial tissues (Bovenhuis et al., 2016).

Association studies using different bovine populations supported the role of DGAT1 as a functional gene candidate for traits of deposition of fat in beef cattle breeds. DGAT1 action in fat depositions is mainly inferred due to its role in triglycerides synthesis (Zhang et al., 2015) and its EST (expressed sequence tags) of adipose tissue (Tantia et al., 2006).

The current is a cross-sectional study involving 106 Nelore bulls, recorded as cattle of pure origin (PO) through the national registry from the Brazilian Association of Zebu Breeders. Peripheral blood was collected from each animal and subsequently used to isolate genomic DNA, using a commercial kit (Illustra Blood Genomic Prep Mini Spin®, GE Healthcare, UK) according to the manufacturer's instructions. DNA purity and concentration were determined in a spectrophotometer (Nanodrop®, Thermo Fisher Scientifc, USA).

Isolated DNA was used to amplify genomic regions targeting single nucleotide polymorphism (rs471462296 [A/G], rs456245081 [A/G], and rs438495570 [C/G]) in the 5’UTR of DGAT1 gene. SNPs were amplified by qPCR using TaqMan® Assays (Applied Biosystems, USA). Thermocycling was carried out in a StepOne® Real-Time PCR System (Thermo Fisher Scientific, EUA) following the manufacturer’s instructions. Amplicons were analyzed using the software StepOne® Analyzer v.2.1 (Thermo Fisher Scientific, EUA). Allele calling followed the probe signals and instructions recommended by the manufacturer.

In the current study all genotypes were monomorphic. All animals were homozygous AA for rs47146229 and rs456245081 and heterozygous CG for rs438495570 (Table 1).

Table 1
Allele and genotypes frequencies for the SNPs for the group tested

Group	DGAT1/SNP	Allele frequencies		Genotypes frequencies
		+	-	+/+	+/-	-/-
G1-Nelore (n= 73)	rs471462296	1,00	0,00	1,00	0.00	0,00
	rs456245081	1,00	0,00	1,00	0.00	0.00
	rs438495570	0.50	0.50	0.00	1,00	0.00

• n number of animals; + Commum alele; - Mutant alele; +/+ Homozygous for commum alele; +/- Heterozygous for mutante alele; -/- Homozygous for mutant alele.

Our results suggested the 5’UTR of DGAT1 gene had low sequence diversity and low variability in Nelore breed. Most likely founder effect and artificial breeding selection are the main causes for reduced variability of the aforementioned SNPs (Anton et al., 2008). Although much interest has been associated with the role of DGAT1 in the deposition of intramuscular fat in Nelore, the studied SNPs presented little value as molecular markers for such trait as it wasn’t possible to construct useful haplotypes to guide genetic merit of the breed (Mishra et al., 2007). On the other had, due to the monomorphic genotypes found, the evidence of any direct effect of DGAT1 on fat deposition cannot be ruled out in Nelore. In summary, our results were important to consolidate the knowledge about single nucleotide variation in DGAT1 gene for different bovine breeds. Thus, allowing for the adequate selection of SNP markers to be used in association studies and in the discrimination of animals of higher genetic value for phenotypes of economic interest.

ACKNOWLEDGMENTS

The authors would like to thank CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior for their financial support.

REFERENCES

• ANTON, I.; KOVÁCS K.; FÉSÜS L. et al. A. Effect of DGAT1 and TG gene polymorphisms on intramuscular fat and on milk production traits in different cattle breeds in Hungary. Acta. Vet. Hung. v.56, p.181-186, 2008.
• BOVENHUIS, H.; VISKER, M.H.P.W.; POULSEN, N.A. et al. J. Effects of the diacylglycerol o-acyltransferase 1 (DGAT1) K232A polymorphism on fatty acid, protein, and mineral composition of dairy cattle milk. J. Dairy Sci., v.99, p.3113-3123, 2016.
• KAUPE, B.; WINTER, A.; FRIES, R. et al. DGAT1 polymorphism in Bos indicus and Bos taurus cattle breeds. J. Dairy Res., v.71, p.182-187, 2004.
• MISHRA, B.; MADHU S.; TANTIA S.T. et al., Bina et al. Characterization of the DGAT1 gene in the Indian buffalo (Bubalus bubalis). Genet. Mol. Biol., v.30, p.1097-1100, 2007.
• TABARAN, A.; BALTEANU, V.A.; GAL E. et al. Influence of DGAT1 K232A polymorphism on milk fat percentage and fatty acid profiles in Romanian Holstein cattle. Anim. Biotechnol., v.26, p.105-11, 2015.
• TANTIA, M.S.; RAMESH, K.V.; BISHNU, P.M. et al. DGAT1 and ABCG2 polymorphism in Indian cattle (Bos indicus) and buffalo (Bubalus bubalis) breeds. BMC Vet. Res. v.2, p.32, 2006.
• ZHANG L.P., GAN Q.F., HOU G.Y.. et al. Investigation of TG gene variants and their effects on growth, carcass composition, and meat quality traits in Chinese steers. GENET MOL RES. n.22, v.14. 2015.

Publication Dates

• Publication in this collection
  06 June 2019
• Date of issue
  Mar-Apr 2019

History

• Received
  24 June 2017
• Accepted
  14 Nov 2018