Distinction between mouse DNA polymerases alpha and beta by tryptic peptide mapping.

Results presented here and in a previous paper (Tanabe et al. (1979) Biochemistry 18, 3401--3406) indicate that mouse beta-polymerase is a single polypeptide with an apparent molecular weight of 40,000. This polypeptide has now been analyzed by tryptic peptide mapping. Comparison of the results with identical analysis of mouse alpha-polymerase reveals that the tryptic peptides derived from the two enzymes are different. These results indicate that beta-polymerase is neither a subunit of alpha-polymerase nor a proteolytic degradation product of alpha-polymerase.     

Effects of preparation and fixation on three quantitative fluorescent cytochemical procedures

A series of experiments was undertaken in which cells dissociated from the abdominal lymph nodes of mice were lightly centrifuged into slides and fixed either wet or after drying in 70% ethanol, 1% glutaraldehyde, 1% formaldehyde, or neutral formalin. Three fluorescent cytochemical methods were evaluated: staining of DNA with mithramycin; fluorochroming of basic groups of proteins with brilliant sulfaflavine (BSF); and staining of sulfhydryl and disulfide groups with N-(7-dimethylamino-4-methylcoumarinyl)maleimide (DACM). In the case of mithramycin, the best results were obtained after fixation in 70% ethanol without drying. Staining of dried preparations fixed in 1% glutaraldehyde also yielded reasonably consistent results, although the fluorescence was lower, and the variability higher, than in the group fixed without drying in 70% ethanol. The use of fixatives containing formaldehyde resulted in fluorescence values of only about one-third those of the other two groups, and the variability of the data was higher. In material stained with BSF, satisfactory results were obtained in preparations fixed without drying in neutral formalin containing mersalyl acid. Other fixatives could be used, but the resulting coefficients of variation were higher than those of formalin-fixed material. Sulfhydryl to disulfide ratios approaching those expected from biochemical evidence were obtained in DACM-stained material only after fixation without drying in neutral formalin containing mersalyl acid. Inverted sulfhydryl-disulfide ratios were observed in material fixed without drying in 70% ethanol; and in dried material fixed in 1% formaldehyde, neutral formalin, or 1% glutaraldehyde.     

Influence of antibiotics and trace salts on lysine production by arthrobacter globiformis

A hydrocarbon utilizing strain of Arthrobacter globiformis Lb isolated from local soil has been found to yield lysine 3.4 g l^?1, keeping the medium optimal for pH, C- and N-sources. Addition of antibiotics and micronutrients to that optimal media stimulated cell growth and enhanced lysine yield.     

Synthesis of peptides from amino acids and ATP with lysine-rich proteinoid

Summary Lysine-rich proteinoids in aqueous solution catalyze the formation of peptides from free amino acids and ATP. This catalytic activity is not found in acidic proteinoids, even though the latter contain some basic amino acid. The pH optimum for the synthesis is about 11, but is appreciable below 8 and above 13. Temperature data indicate an optimum at 20°C or above, with little increase in rate to 60°C. Pyrophosphate can be used instead of ATP, with lesser yields resulting. The ATP-aided syntheses of peptides in aqueous solution occur with several types of proteinous amino acid.Proofs should be sent to S.W. Fox, Institute for Molecular and Cellular Evolution, University of Miami, 521 Anastasia Avenue, Coral Gables, FL 33134     

A note on antibiotic-resistant Escherichia coli in adult man, raw sewage and sewage-polluted River Tigris in Mosul, Nineva

A total of 600 isolates of Escherichia coli were isolated, over a 9 month period during 1984, from healthy human adults, raw sewage and the sewage-polluted River Tigris in Nineva. Over 90% of these organisms were E. coli type 1, but only 8.3% could be serogrouped as enteropathogenic E. coli . Resistance of these organisms to 11 antimicrobial drugs was assessed. Over 40% were antibiotic-resistant and of these 77.1% were resistant to more than one antibiotic. The minimal inhibitory concentration of ampicillin for 193 selected strains from the various sources was determined and ranged from <0.625- > 160 μg/ml. The high incidence of antibiotic-resistant E. coli in this locality and the possible implications to human health are discussed.     

The microbial degradation of morpholine

Morpholine can be completely degraded microbiologically, and two organisms have been isolated, each capable of growth in a simple mineral salts medium with morpholine as the sole source of carbon, nitrogen and energy. Excess nitrogen is liberated as ammonia. The enzymes responsible for the oxidation of morpholine are inducible and, in organism Mor G, will also oxidize piperidine, piperazine and pyrrolidine, which are not growth substrates. Ethanolamine is a likely intermediate, though the metabolic steps in morpholine degradation do not give rise solely to acetyl-CoA. After a period of acclimation, a laboratory scale activated sludge plant effectively removed morpholine over the long period it was operated; the sludge was also capable of nitrification. The possible effects of other chemicals in trade wastes containing morpholine on nitrification and morpholine oxidation are described.