| 摘要 |
The invention relates to new methods of RNA isolation that exploit the surprising discovery that RNA may be differentially precipitated from DNA. The subject methods result in the formation of an RNA-containing precipitate that has an RNA content at least two fold enriched with respect to DNA, as compared with the RNA to DNA ratio of the solution from which the RNA-containing precipitate is derived. The invention also includes various methods of DNA isolation that employ the selective precipitation of RNA. The degree of RNA enrichment achieved is often much greater than two fold; enrichment by a factor of ten or greater is frequently obtained. By precipitating RNA from a solution, the RNA may be collected by simple procedures such as centrifugation or filtration, thereby avoiding the need to bind the RNA to solid phase. The collected RNA precipitate may then be solubilized. One embodiment of the subject methods involves forming an RNA-containing nucleic acid composition, adding an RNA precipitate forming chaotropic salt to the nucleic acid composition in a sufficient concentration to form an RNA-containing precipitate, collecting the RNA-containing precipitate, and (optionally) solubilizing the precipitate. Preferred precipitate forming chaotropic salts are guanidine hydrochloride and guanidine thiocyanate. Other embodiments of the invention include kits for performing the methods of the invention. The invention also includes systems for performing the methods of the invention. |
