Allele Quantitation

Pyrosequencing is a quantitative DNA sequencing technique because the intensity of a light signal is accurately correlated to the amount of nucleotide incorporated. This fact enables pyrosequencing to be applied to quantifying allele frequencies of SNPs,[15] estimating global DNA methylation,[16] and detecting variations in the copy numbers of duplicated genes.[17] The pyrosequencing SNP software automatically analyzes SNP genotyping data and quantifies the allele frequencies of SNPs.

Linkage disequilibria of SNPs have been employed to identify susceptibility genes for complex diseases. Although high-throughput techniques have been applied for accuracy and large-scale SNP genotyping, using individual genotyping is expensive and time-consuming for assays with large sample sizes and that also scan for numerous alleles. Directly assaying SNP allele frequencies in pooled DNA samples provides the advantages of higher throughput and lower cost. An accurate and reproducible assay is critical for determining SNP frequencies using DNA pools. The ability to quantify the amount of incorporated nucleotide enables pyrose-quencing to accurately estimate the SNP allele frequencies in DNA pools. The correlation coefficients between estimated SNP allele frequencies in DNA pools and that of true allele frequencies were demonstrated to be between 0.979 and 0.996.[15,18] Scanning SNP allele frequencies in DNA pools allows the rapid estimation of the linkage disequilibria of SNPs in susceptibility genes in the genetic study of complex diseases.

DNA methylation is an epigenetic modification of DNA that plays an important role in controlling gene expression, regulating X-chromosome inactivation, DNA repair, and tumorigenesis.[19,20] In mammals, DNA methylation occurs at the 5-position of the pyrimidine ring of cytosine in the context of dinucleotide CpG. Quantifying global DNA methylation or DNA methyla-tion in a specific locus is important for understanding the regulation of gene expression and inactivation of genes throughout the genome. The pyrosequencing technique has been demonstrated to be an accurate and high-throughput method for quantitating DNA methyla-tion.[16,20] This method is based on bisulfite treatment of genomic DNA, which converts unmethylated cytosines to uracils, such that the ratio of methylated cytosines to unmethylated ones can be quantified as C/T SNP using the pyrosequencing allele frequency analysis program.

Getting Started With Dumbbells

Getting Started With Dumbbells

The use of dumbbells gives you a much more comprehensive strengthening effect because the workout engages your stabilizer muscles, in addition to the muscle you may be pin-pointing. Without all of the belts and artificial stabilizers of a machine, you also engage your core muscles, which are your body's natural stabilizers.

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