Growth response of Nitrosomonas europaea to amino acids

Growth responses of Nitrosomonas europaea to individual amino acids or vitamins was observed in log-phase cultures, as was the incorporation of carbon-14 labeled amino acids. Nitrite formation and protein synthesis were increased by l-glutamic acid, l-aspartic acid, l-serine, and l-glutamine. l-Lysine, l-histidine, l-threonine, l-valine, l-methionine, and l-arginine were inhibitory. The other amino acids had no effect on growth. All of the uniformly labeled amino acids added at low concentrations were taken up by growing cells and distributed into cell fractions. From 1 to 12% of the added radioactivity was present in cells analyzed in late log phase, depending on the amino acid; glycine and l-serine caused accumulation of the label to the greatest extent, whereas l-aspartic and l-glutamic acids were among those incorporated to the least extent. Aspartic acid increased both cell protein and nitrite values, but did not alter the ratio of protein to nitrite from that found in controls.     

Serology of Rubella—Comparison of Fluorescent Antibody,Complement Fixation and Neutralization Tests for Diagnosis of Current Infections and Determination of Sero-immunity

Neutralization, complement fixation (CF) and indirect fluorescent antibody (FA) assays for rubella virus were compared for sensitivity in the serologic diagnosis of infection, for demonstrating antibody in the sera of infants with suspected rubella syndrome, and in the detection of antibody elicited by past infection (determination of immunity status). The combination of CF and FA tests was shown to be the most useful for serologic diagnosis of infection, largely eliminating the need for the slower and more cumbersome interference neutralization test.Neutralizing antibodies were found to appear rapidly in the course of infection, antibodies demonstrable by immunofluorescent staining appeared slightly later, and CF antibodies were rarely demonstrable in sera collected earlier than 14 days after onset of illness. Antibodies detected by all three techniques showed good correlation in infants with clinical evidence of rubella syndrome and corresponding maternal sera. The indirect FA technique compared favorably with the neutralization test for the detection of antibody elicited by past infection (determination of immunity status) and offered distinct advantages in ease of technical performance and more rapid results. In both current and past infections, FA titers tended to be higher than neutralizing antibody titers.     

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