Patent ID: 7332284

Claim:
A method of determining the sequence bases of a DNA or RNA, comprising the steps of: (a) providing a support film, on which an elongated single-chain DNA or RNA is held, on an electron microscope grid; (b) exposing the elongated single-chain DNA or RNA on the support film to a guanine derivative, an adenine derivative, a cytosine derivative, and a uracil derivative, each derivative containing a different heavy element label comprising a heavy element or elements (c) allowing the guanine derivative, the adenine derivative, the cytosine derivative, and the uracil derivative to form base pairs with the single-chain DNA or RNA in the presence of an organic solvent to form a base-specific labeled elongated single-chain DNA or RNA; (c) obtaining a magnified image of a portion of the base-specific heavy element labeled elongated single-chain DNA or RNA, wherein the portion of DNA or RNA does not cross itself using a transmission electron microscope and discriminating said base-specific labels of heavy elements using the obtained magnified image.