Which culture medium is specifically recommended for demonstrating sister chromatid exchange?

The choice of BrdU (Bromodeoxyuridine) culture medium is specifically recommended for demonstrating sister chromatid exchange because BrdU is a thymidine analogue that gets incorporated into DNA during the S-phase of the cell cycle. When cells are exposed to BrdU, it incorporates into the DNA strands, allowing for the visualization of DNA replication and the occurrence of sister chromatid exchange events.

When chromosomes are subsequently analyzed under fluorescent microscopy with appropriate staining techniques, regions where BrdU has substituted for thymidine are highlighted. This distinction facilitates the identification of sister chromatid exchanges, as they will show up as differing fluorescent signals on chromatids.

This is particularly useful in cytogenetic studies aimed at understanding genetic instability and the mechanisms of carcinogenesis, as sister chromatid exchanges can indicate responses to DNA damage or genetic repair processes. Other culture media listed do not provide this specific capability in demonstrating the occurrence of sister chromatid exchanges due to the lack of a similar incorporation mechanism or fluorescent marking.