An 18.5-kb human DNA segment was selected from a human XCharon-4A library by hybridization to mammalian valine tRNAiAc and found to encompass a cluster of three tRNA genes. Two valine tRNA genes with anticodons of AAC and CAC, encoding the major and minor cytoplasmic valine tRNA isoacceptors, respectively, and a lysine tRNAcuu gene were identified by Southern blot hybridization and DNA sequence analysis of a 7.1-kb region of the human DNA insert. At least nine Alu family members were found interspersed throughout the human DNA fragment. The tRNA genes are accurately transcribed by RNA polymerase III in a HeLa cell extract, since the RNase Ti fingerprints of the mature-sized tRNA transcription products are consistent with the DNA sequences of the structural genes. Three members of the chimpanzee triosephosphate isomerase (TPI) gene family, the functional transcription unit and two processed pseudogenes, were characterized by genomic blotting and DNA sequence analysis. The bona fide TPI gene spans 3.5 kb with seven exons and six introns, and is the first complete hominoid TPI gene sequenced. The gene exhibits a very high identity with the human and rhesus TPI genes. In particular, the polypeptides of 248 amino acids encoded by the chimpanzee and human …

Intracellular levels of NAD are of renewed interest in clinical and basic science research due to the new discovery of enzymes which utilize NAD as a substrate. Microtiter assays for the determination of NAD, NADP and protein were developed as modifications of previously published methods. The resulting assays are simple, cost effective and sensitive. An improved method of isolating lymphocytes was also developed. The resultant procedure requires one hour and removes greater than 99.9% of the platelets. Lymphocyte pools were stabilized with the addition of ADP-ribosyltransferase inhibitors and a modified extraction procedure. These studies have led to the development of a method for evaluation of NAD in human lymphocytes that is sensitive, selective and suitable for automation.