Bisulfátszekvenálás

Bisulfátszekvenálás, also known as bisulfite sequencing or whole-genome bisulfite sequencing (WGBS) when applied to the entire genome, is a molecular biology technique used to determine the methylation status of cytosine bases in DNA. Methylation, the addition of a methyl group to a cytosine, is a crucial epigenetic modification that plays a significant role in gene regulation, DNA replication, and genome stability.

The process begins with treating DNA with sodium bisulfite. This chemical selectively deaminates unmethylated cytosines to uracils, while methylated cytosines remain unchanged. Following bisulfite treatment, the DNA is typically amplified using polymerase chain reaction (PCR). Since uracils behave like thymines during PCR, the amplified DNA sequences will reflect the original methylation pattern. Specifically, positions that were unmethylated cytosines will appear as thymines in the sequenced product, while methylated cytosines will be read as cytosines.

After amplification, the DNA fragments are sequenced using standard methods, such as next-generation sequencing. The resulting sequencing reads are then aligned to a reference genome. By comparing the sequenced reads to the reference, researchers can identify cytosines that were converted to uracils (indicating unmethylated cytosines) and those that remained cytosines (indicating methylated cytosines). This allows for the precise mapping of methylation patterns across the genome.

Bisulfátszekvenálás is a powerful tool for studying epigenetics. It is used to investigate how methylation patterns change in different cell types, during development, in response to environmental factors, or in disease states like cancer. By understanding DNA methylation, scientists can gain insights into gene expression regulation and the molecular mechanisms underlying various biological processes.