Avaliação de protocolos para extração de DNA Genômico de sangue Bovino

Basic studies on DNA extraction techniques are very important for the success of scientific papers in the field ofmolecular biology. The extraction and purification of nucleic acids are critical steps for establishing further geneticanalysis. The objective of this study was to evaluate the efficacy of different protocols for DNA extraction by deter- mining the quantity and quality of extracted genetic material and the possibility of amplification by PCR. We didDNA extraction and PCR of ten bovine blood samples. The test results obtained by spectrophotometry indicated thatthe quantity and quality of genomic DNA were considered satisfactory in all protocols for PCR. However, there wasa statistically significant difference between the parameters measured, both in quantity and in quality (p <0.01). Theextraction protocol using whole blood was more efficient in terms of time and quality; there was no degradation inall processes of extraction. It was also demonstrated that the possibility of amplification of the region of exon 2 ofthe leptin gene in extracted DNA exists.Estudos básicos sobre técnicas de extração de DNA são de extrema importância para o sucesso de trabalhos científicos no campo da biologia molecular. A extração e a purificação de ácidos nucleicos constituem etapas fundamentaispara o estabelecimento de posteriores análises genéticas. Objetivou-se neste trabalho avaliar a eficácia de diferentesprotocolos de extração de DNA por meio da determinação de quantidade, qualidade e a possibilidade de amplificação por meio de PCR do material genético extraído. Utilizou-se amostras de sangue de dez animais, que foramsubmetidas à extração de DNA e, logo após à reação em cadeia pela polimerase (PCR). Os resultados das análisesobtidas por nanofotometria indicaram que a quantidade e a qualidade do DNA genômico foram consideradas satisfatórias, em todos os protocolos, para a realização da PCR, mas houve diferença estatística significativa entre osparâmetros analisados, tanto na quantidade quanto na qualidade (p < 0.05) do DNA obtido. O protocolo de extraçãoutilizando sangue total foi mais eficiente quanto ao tempo e a qualidade do DNA extraído, entretanto em todos osprocessos de extração houve ausência de degradação. Também foi demonstrado a possibilidade de amplificação daregião do exon 2 do gene da leptina de bovinos no DNA extraído

Evaluation protocols for the extraction of genomic DNA from Bovine blood

Basic studies on DNA extraction techniques are very important for the success of scientific papers in the field of molecular biology. The extraction and purification of nucleic acids are critical steps for establishing further genetic analysis. The objective of this study was to evaluate the efficacy of different protocols for DNA extraction by determining the quantity and quality of extracted genetic material and the possibility of amplification by PCR. We did DNA extraction and PCR of ten bovine blood samples. The test results obtained by spectrophotometry indicated that the quantity and quality of genomic DNA were considered satisfactory in all protocols for PCR. However, there was a statistically significant difference between the parameters measured, both in quantity and in quality (p <0.01). The extraction protocol using whole blood was more efficient in terms of time and quality; there was no degradation in all processes of extraction. It was also demonstrated that the possibility of amplification of the region of exon 2 of the leptin gene in extracted DNA exists

Genome-wide association study using haplotype alleles for the evaluation of reproductive traits in Nelore cattle

<div><p>Zebu cattle (<i>Bos taurus indicus</i>) are highly adapted to tropical regions. However, females reach puberty after taurine heifers, which affects the economic efficiency of beef cattle breeding in the tropical regions. The aims of this study were to establish associations between the haplotype alleles of the bovine genome and age at first calving (AFC) in the Nelore cattle, and to identify the genes and quantitative trait loci (QTL) related to this phenotype. A total of 2,273 Nelore cattle (995 males and 1,278 females) genotyped using the Illumina BovineHD BeadChip were used in the current study. The association analysis included females with valid first calving records as well as open heifers. Linkage disequilibrium (LD) analysis among the markers was performed using blocks of 5, 10, and 15 markers, which were determined by sliding windows shifting one marker at a time. Then, the haplotype block size to be used in the association study was chosen based on the highest r² average among the SNPs in the block. The five HapAlleles most strongly associated with the trait (top five) were considered as significant associations. The results of the analysis revealed four genomic regions related to AFC, which overlapped with 20 QTL of the reproductive traits reported previously. Furthermore, there were 19 genes related to reproduction in those regions. In conclusion, the use of haplotypes allowed the detection of chromosomal regions associated with AFC in Nelore cattle, and provided the basis for elucidating the mechanisms underlying this trait.</p></div

Top five regions of the GWAS with haplotypic blocks, indicating the chromosomal localization (Chr), start and end positions, the respective SNPs, size and p-values.

<p>Top five regions of the GWAS with haplotypic blocks, indicating the chromosomal localization (Chr), start and end positions, the respective SNPs, size and p-values.</p

Summary of the genes present in 1-MB windows centered on the haplotypes that were top five significant haplotype alleles.

<p>Summary of the genes present in 1-MB windows centered on the haplotypes that were top five significant haplotype alleles.</p

Manhattan plot of the genomic-wide association analysis of the –log₁₀ (p-value) of haplotype alleles and AFC trait.

<p>Each point in the graph represents a haplotype allele, arrows indicates de top five significant genomic regions and respective genes. The dashed line represent–log10(5 x 10⁻⁵) threshold.</p