Bisulfitebased

Bisulfite-based refers to methods or processes that use chemical bisulfite reagents, typically sodium bisulfite, to effect targeted chemical changes in biomolecules, most commonly DNA. In this context, the essential idea is to exploit the differential reactivity of cytosine bases under acidic, bisulfite treatment: unmethylated cytosines are deaminated to uracil, which is read as thymine during PCR and sequencing, while 5-methylcytosine remains unaltered. This differential conversion creates sequence-level signals that report cytosine methylation status at single-base resolution after subsequent amplification and sequencing.

Bisulfite-based DNA methylation analysis includes whole-genome bisulfite sequencing (WGBS), reduced representation bisulfite sequencing (RRBS), targeted bisulfite sequencing, and methylation-specific PCR (MSP). Data analysis requires aligning bisulfite-converted reads with specialized software that accounts for C-to-T conversions, such as Bismark or BS-Seeker, and calculating methylation levels at cytosine positions. Typical challenges include incomplete conversion, DNA degradation from harsh treatment, and the need for appropriate controls and validation.

Beyond epigenetics, bisulfite chemistry is used in food preservation and winemaking historically for sulfiting agents, though “bisulfite-based” in this sense refers to reagents rather than sequencing methodologies. In laboratory contexts, bisulfite-based approaches require careful handling due to the corrosive and irritant nature of bisulfite reagents and the potential for sample degradation.