Blasticidin S is an antibiotic that is produced by Streptomyces griseochromogenes. In biological research, specifically genetic engineering, it is used to select transformed cells which have been engineered to carry a resistance gene for blasticidin. In short, DNA of interest is fused to DNA encoding a resistance gene, and then is transformed into cells.
Puromycin is an antibiotic researchers can use when working with cell cultures when they need a selective agent, a compound that will kill all cells without resistance genes, leaving only specific targets behind. This antibiotic is available through laboratory suppliers and is suitable for research purposes only.