Cell mass, the average number of nuclei/cell and the content of RNA and DNA were studied in Salmonella typhimurium during balanced (steady state) growth in different media. These quantities could be described as exponential functions of the growth rates afforded by the various media at a given temperature. The size and chemical composition characteristic of a given medium were not influenced by the temperature of cultivation. Thus, under conditions of balanced growth, this organism exists in one of a large number of possible stable physiological states. The variations in mass/cell are due to changes in the number of nuclei/cell as well as in mass/nucleus. An increase in the number of ribonucleoprotein particles at higher growth rates could, it appears, largely account for the increase in mass/nucleus. Calculations indicate that the rate of protein synthesis per unit RNA is nearly the same at all growth rates.

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Dependency on Medium and Temperature of Cell Size and Chemical Composition during Balanced Growth of Salmonella typhimurium

Three categories of phosphatase activity toward adenosine triphosphate at pH 9.4 have been isolated histochemically: (1) phosphatase which requires -SH groups; (2) phosphatase which is inhibited by -SH groups; and (3) phosphatase which is relatively indifferent to -SH groups. This enzymatic activity was demonstrated in thin (5 µ), unfixed, frozen sections.True adenosine triphosphatase has been separated histochemically by virtue of its -SH dependence. It was demonstrated in cardiac and skeletal muscle fibers and in the mitochondria of the kidney tubules. The staining of these structures can be prevented by treatment with an -SH inhibitor, such as p-chloromercuribenzoate or salyrganic acid. Also their stainability can be restored by reversing the inhibition of the enzymes with -SH compounds, such as BAL or cysteine. There was no reaction of these particular structures when adenosine diphosphate or adenosine-5-phosphate was used, suggesting that under the conditions of this histochemical test only the termi...

The specificity of the histochemical method for adenosine triphosphatase.

Separation and estimation of amino acids in crude plant extracts by thin-layer electrophoresis and chromatography

Determination of organic phosphorus compounds by phosphate analysis.

Studies on the role of ribonucleic acid in the growth of bacteria.

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Fractionation of phosphates by paper ionophoresis and chromatography.

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The nature of the fluctuating ribonucleic acid in Escherichia coli.

The importance of adenosine triphosphate (ATP) in cell metabolism and the instability of its preparations during storage have resulted in a keen interest being shown in methods for its analysis. Until recently the most satisfactory analysis of ATP has involved the preparation and use of highly purified enzyme systems (Bailey, 1949). Other less time-consuming methods involving paper chromatography are now available. The most recent (Eggleston & Hems, 1952) involves the separation and estimation of ATP, adenosine 5-phosphate (AMP),orthophosphateandpyrophosphate + adeno. sine diphosphate (ADP) by 'two-solvent onedimensional chromatography' and the individual determination of pyrophosphate by a further chromatographic separation. During the development of a general scheme for the analysis of acid-soluble phosphates a method involving paper ionophoresis was evolved which was found to separate all the above esters in one operation and in the space of a few hours. The technique which is described below has been applied to the analysis. of seven samples of ATP and one of ADP.

D. M. Morgan

Papers

Fractionation of phosphates by paper ionophoresis and chromatography.

The nature of the fluctuating ribonucleic acid in Escherichia coli.

The analysis of adenosine triphosphate and adenosine diphosphate preparations by paper ionophoresis.