Standard molecular biology techniques are used widely in biomedical research and have had a major impact on the understanding of physiologic processes and disease mechanisms. They also play an increasing role in molecular genetic diagnosis and new therapeutic approaches. This laboratory manual is designed for researchers who need reliable pro­ ols for their laboratorywork. It provides a step by step approach to stan­ dard methods of molecular biology. A wide range of topics is covered by prools for immediate application in the laboratory. These include pur­ ification, isolation, labeling, hybridization, sequencing and enzymatic mod­ ification ofDNA or RNA, polymerase chain reaction, cloning, libraries, and protein techniques. The manual is based on experience with a practical course in molecular biologytechniques, which was taught bythe authors. Since most methods in molecular biology recapitulate in a test tube mechanisms that occur natu­ rally in the cell, the first three chapters describe and illustrate basic mechanisms of molecular biology. U nderstanding more about these basic mechanisms will enable the researcher to apply techniques more specifically, based on the knowledge of their potential and limits. W e hope that users find this manual a helpful guide on their road to exciting insights.