The genes for fifteen ribosomal proteins of Saccharomyces cerevisiae

We have isolated recombinant lambda phage carrying the genes for 14 of the ribosomal proteins of the yeast Saccharomyces cerevisiae. Analysis of these and of the plasmid carrying the gene tcm1, which codes for the ribosomal protein responsible for resistance to trichodermin, demonstrates that in general the genes for ribosomal proteins are unlinked. One exceptional recombinant carries the genes for two ribosomal proteins within a 2-kilobase region. DNA fragments bearing individual ribosomal protein genes were used to probe restriction digests of the yeast genome to determine whether any of the genes were duplicated. Only 3 of 12 of the genes are present unequivocally as a single copy. Similar fragments were used to probe blots of mRNA separated on denaturing agarose gels to determine the size of the mRNA for each protein. In each case, the mRNA is near the minimum size necessary to code for its protein. In certain temperature-sensitive mutants which fail to synthesize functional mRNA for ribosomal protein, Rosbash et al. (Rosbash, M., Harris, P. K. W., Woolford, J., and Teem, J. L. (1981) Cell, 24, 679-686) have demonstrated the accumulation of a larger RNA molecule, homologous to a ribosomal protein gene, that appears to be a transcript which retains an intervening sequence. We find that for 8 of the 11 ribosomal protein genes examined, a larger molecule accumulates in such a mutant strain, suggesting that in general transcripts of ribosomal protein genes may have introns.

Fenestration of the anterior cerebral artery

Three cases of angiographically demonstrated fenestration of the anterior cerebral artery are reported. Fenestration occurred at the medial half of the horizontal segment of the anterior cerebral artery in all cases. Its embryology and clinical significance are briefly discussed, and the anatomical and radiological literature on fenestration of the anterior cerebral artery is reviewed.

Mycobacterium leprae: atypical and unclassified

Once M. leprae is grown on artificial media in the test tube, it might prove to have a great variety of characteristics quite different to those expected from our knowledge of M. leprae isolated from the susceptible host. The cultures might be slow or fast growing, pigmented or colorless, pathogenic for the armadillo, or not; they might produce limited disease in the foot pad of mice, or the contrary. The in vitro M. leprae culture might or might not provoke a lepromine reaction; the culture might grow at a lower or higher temperature. It is well documented that mycobacteria show great differences in elasticity and adaptability to cultivation conditions. It is absolutely certain that once grown in a test tube, M. leprae will behave as an atypical species. However, each individual culture of M. leprae obtained in vitro will have the same drug sensitivity pattern as in the lepromatous leprosy patient from whom it was cultivated.

Hypermethioninemia in an infant

We discuss an infant with hepatitis and hypermethioninemia. An inborn error of metabolism, such as methionine adenosyltransferase deficiency or hereditary tyrosinemia, was originally thought to be the basis for these abnormalities. The infant's subsequent clinical course, however, was incompatible with such a diagnosis; the hypermethioninemia was instead due to the trilogy of prematurity, hepatitis, and a high-protein, high-methionine diet.

Spatial configuration of mRNA 5'-terminus

Nuclear magnetic resonance investigation has revealed that the 5'-terminus m7G5'ppp5'Am of mRNA displays a spatial configuration in which the bases form stacked arrays. Details of the conformation as derived from coupling constants, shift trends and ring current considerations are discussed.

A modified nephrostomy in the management of urinary fistula after renal transplantation

A technique for complete urinary diversion was used in the management of urinary fistula following renal transplantation. Nephrostomy was modified by closing the renal pelvis at the ureteropelvic junction. No impairment of renal function occurred. In the presence of infection, it is reasonable first to treat the infection and postpone the reconstructive procedure until the infection has subsided.