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PubMed1962

Photographic cytophotometry with a dual microscope.

A modified comparison microscope assembly was developed for quantitative cytochemical analysis of stained or naturally pigmented objects. Test and control objects were photographed simultaneouslyon the same frame of color film. Pigments in the film image were then extracted and analyzed in a recording spectrophotometer. The total procedure is an extension and simplification of existing methods.

Cell Biology↗
PubMed1964

PHENOLOXIDASE SYSTEM OF THE BLOWFLY, CALLIPHORA ERYTHROCEPHALA.

In Calliphora larvae, an inactive precursor of the enzyme phenoloxidase is present in the hemolymph. A special activator enzyme is localized in the cuticle. When phenoloxidase precursor is allowed to react with the activator, it yields a soluble enzyme having the characteristics mainly of a diphenoloxidase. If, however, this conversion takes place in the presence of mitochondria, the phenoloxidase becomes bound to the mitochondria and the resulting preparation shows equally mono- and diphenoloxidase activity.

Animals↗
PubMed1965

AMINO ACID ISOMERIZATION IN THE PRODUCTION OF L-PHENYLALANINE FROM D-PHENYLALANINE BY BACTERIA.

To establish an advantageous method for the production of l-amino acids, microbial isomerization of d- and dl-amino acids to l-amino acids was studied. Screening experiments on a number of microorganisms showed that cell suspensions of Pseudomonas fluorescens and P. miyamizu were capable of isomerizing d- and dl-phenylalanines to l-phenylalanine. Various conditions suitable for isomerization by these organisms were investigated. Cells grown in a medium containing d-phenylalanine showed highest isomerization activity, and almost completely converted d- or dl-phenylalanine into l-phenylalanine within 24 to 48 hr of incubation. Enzymatic studies on this isomerizing system suggested that the isomerization of d- or dl-phenylalanine is not catalyzed by a single enzyme, "amino acid isomerase," but the conversion proceeds by a two step system as follows: d-pheylalanine is oxidized to phenylpyruvic acid by d-amino acid oxidase, and the acid is converted to l-phenylalanine by transamination or reductive amination.

Amino Acids↗
PubMed1962

Metabolism of resistant mutants of Streptococcus faecalis. IV. Use of a biophotometer in growth-curve studies.

Coultas, M. Katharine (Sloan-Kettering Institute for Cancer Research, Rye, N.Y.) and Dorris J. Hutchison. Metabolism of resistant mutants of Streptococcus faecalis. IV. Use of a biophotometer in growth-curve studies. J. Bacteriol. 84:393-401. 1962. - Analysis of data obtained using the Bonet-Maury and Jouan biophotometer has shown it to be an accurate, automatic device for recording an entire bacterial growth curve, from which quantitative measurements of growth rate can be calculated. Growth rate values obtained in this manner agree with those obtained by conventional methods. The instrument is described in detail and reference is given to other uses of this type of photometer. The growth curves of Streptococcus faecalis ATCC 8043 and three mutants resistant to purine analogues were compared in media with and without a purine. Differences in these growth curves were evident. In the purine-deficient medium SF/AZAG, the 8-azaguanine-resistant mutant had the shortest doubling time, 61 min, followed by the two 6-mercaptopurine-resistant mutants (SF/MPcc, 72 min; SF/MP, 91 min), and finally the wild strain with a doubling time of 135 min. In the medium supplemented with xanthine, the respective doubling times were 52, 61, 68, and 68 min.

Azaguanine↗
PubMed1964

NUTRITIONAL REQUIREMENTS OF LACTOBACILLUS 30A FOR GROWTH AND HISTIDINE DECARBOXYLASE PRODUCTION.

Guirard, Beverly M. (University of California, Berkeley), and Esmond E. Snell. Nutritional requirements of Lactobacillus 30a for growth and histidine decarboxylase production. J. Bacteriol. 87:370-376. 1964.-The nutritional requirements of Lactobacillus 30a include each of the naturally occurring amino acids, several B vitamins, ascorbic acid, glucose, acetate, and oleate. The nutritional requirements for optimal histidine decarboxylase production (up to 900 muliters of CO(2) per hr per mg of cells) differ to some extent from those for optimal growth. Wholly synthetic and partially defined media are described which produce high enzyme activity, together with rapid and luxuriant growth.

Amino Acids↗
PubMed1965

PHOTOREVERSIBLE ULTRAVIOLET ENHANCEMENT OF INFECTIVITY IN AGROBACTERIUM TUMEFACIENS.

Heberlein, Gary T. (Northwestern University, Evanston, Ill.), and James A. Lippincott. Photoreversible ultraviolet enhancement of infectivity in Agrobacterium tumefaciens. J. Bacteriol. 89:1511-1514. 1965.-Irradiation of a virulent strain of Agrobacterium tumefaciens with short-wavelength ultraviolet light, which reduces viability 50 to 90%, increases its infectivity as measured by the number of tumors initiated per viable bacterial cell on primary pinto bean leaves. A dark treatment of 1.5 to 2 hr between irradiation and inoculation results in a further increase in specific infectivity of as much as fourfold. This increase in infectivity is inhibited by white fluorescent light and light of 402 mmu, but only slightly by 549- or 619-mmu light. These results imply that some change in the deoxyribonucleic acid of the bacterium is responsible for this effect.

Agrobacterium↗
PubMed1964

A USEFUL PHOTOMETRIC TEST FOR THE DIAGNOSIS OF VON WILLEBRAND'S DISEASE.

When small amounts of adenosine diphosphate are added to citrated platelet-rich plasma, the consequent modification of platelets leads to a decrease in optical density. In Von Willebrand's disease the optical density at 610 mmu increases instead of decreasing. This finding is used to study the effects of treatment on this disorder.

Adenine Nucleotides↗
PubMed1965

AUTOMATED ESTIMATION OF SODIUM, POTASSIUM, AND CALCIUM USING THE EPPENDORF FLAME PHOTOMETER.

An Eppendorf flame photometer may be used to estimate sodium, potassium, and calcium in plasma which has been automatically sampled and diluted. Readings may be automatically recorded by feeding the output from the photomultiplier into a sensitive recorder. This method estimates 60 samples an hour, using approximately 0.12 ml. plasma per estimation. The accuracy of the method is discussed.

Blood Chemical Analysis↗
PubMed1965

ERRORS IN THE MEASUREMENT OF SERUM ELECTROLYTES.

When compared with results obtained by the authors in a department of medicine, the values obtained by three hospital laboratories for sodium, potassium, and chloride in normal and pathological sera were found to contain gross errors. In particular, the values obtained on sera from healthy subjects had a wide range when compared with the results obtained by the authors. The maximum acceptable analytical errors are suggested.

Blood Chemical Analysis↗

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