In gene manipulation, different selectable markers with various linkers are necessary. In order to get selectable markers directly, we constructed from pBlueScript SK(-) a series of particular plasmids, pSKsymKm, pSKsymBle, pSKsymEry, pSKsymHyg and pSKsymGm, each contains Kanamycin, Bleomycin, Erythromycin, Hygromycin or Gentamycin resistance cassette. By restriction enzyme digestion and gel extraction, any of five antibiotic resistance genes with specific ends can be conveniently obtained.