Glauco P. Tocchini-Valentini

Tocchini-Valentini has worked for over forty years in the field of molecular biology. His early scientific contributions include the demonstration that genetic transcription is an asymmetric process. Using alpha-DNA, the genome of a bacteriophage isolated from the Tiber's waters, he showed that only one strand of DNA is copied for each unit of transcription. In an effort to identify the E.coli genes coding for factors involved in the synthesis of macromolecules, he utilized tritiated precursor-induced suicide to isolate three sets of temperature-sensitive mutants blocked in DNA, RNA and protein syntheses, respectively. At the end of the sixties, he contributed to the isolation and characterization of both RNA and DNA polymerases of Xenopus laevis, the isolation of the full transcript of the rDNA cistron (a possible template for the synthesis of amplified DNA) and the discovery of Type II DNA topoisomerase. More recently, the study of RNase P and of the tRNA splicing endonuclease from Xenopus germinal vesicles led him to contribute to understanding the rules governing enzyme-substrate interactions and the determination of cleavage sites in tRNA precursors. The latter work has led to a general scheme for targeting of individual mRNAs in eukaryotes.