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Sulphur metabolism in fungi
Abstracts of Papers 77
Radioactive I s o t o p e s in the S t u d y o f S y n t h e s i s P r o c e s s e s in Yeast O r g a n i s m s . R. D. GALTSOVA a n d N. A. POMOSHMKOVA, U.S.S.R. The study of regularities in the biosynthesis of protein and the influence on it of vitamins, amino acids and other organic compounds is simplified by the use of radioactive isotopes, the latter being particularly advantageous in biochemical and selection investigations. In our work, labelled compounds were used in conjunction with chromatographic methods of separating substances. In addition, special microbiological isotope techniques were worked out to speed up a determination of vitamins in the medium. A quantitative determination by these methods of pantothenic acid and pyridoxine is accomplished in accordance with the speed with which pa2 enters the indicator cultures and takes 4~6 hr, whereas the ordinary microbiological methods require from 40 48 hr. For pantothenic acid the method gives reproducible results in the case of a vitamin content of from 0.001 to 0.01 # per ml of medium; in the determination of pyridoxine, from %001 to 0.03 # of vitamin per ml of medium. Our investigations conducted with the aforementioned methods showed that vitamins and amino acids produce an essential influence on the biosynthesis of sulphur-containing amino acids and their inclusion in the protein. If pyridoxine is added to a culture medium which contains a labelled sulphate, the radioactivity is raised by 25 per cent; addition of thiamine or inosite raises absorption of the sulphate 15 per cent; biotin and nicotinic acid do not produce any influence on the inclusion of sulphur; pantothenic acid reduces the rate of absorption of Sas. If pyridoxine, biotin and thiamine are added to the medium simultaneously, the radioactivity of the yeast protein rises 35 per cent. When asparagine or asparaginic acid is added to the culture medium with S35, the radioactivity of the protein increases 25 per cent; glutamic acid does not produce any influence on the rate of absorption of a sulphate; alanine raises the rate of absorption by 15 per cent. The use of radioactive isotopes made it possible to establish the influence of vitamins and amino acids on the synthesis of protein not only in the case of auxoheterotrophic but in auxoautotrophic microorganisms as well.
209 78
S u l p h u r M e t a b o l i s m in Fungi.
JUNE E.
ROBSON, Isotope Division, A . E . R . E . H a r w e l l , U.K. Summary. Rhythmic rises and falls in the sulphur content of growing cells of Eremothecium Ashbyii, Aspergillus niger and Candida albicans have been demonstrated in a synthetic medium containing S35-1abelled sodium sulphate as the sole source of sulphur. In E. Ashbyii, Sa5 concentrates initially in the cell wall and then in the protoplasm until the sulphur distribution is equal. Growth then begins and the amount of sulphur in the hyphae drops rapidly. When growth has ceased a small quantity of sulphur remains in the cell wall. Changes in the S35 content are complemented by similar changes in the medium. Sulphate is metabolized extracellularly into at least five different compounds some of which disappear before growth begins; others appear when ,growth is taking place. Amino acids, sulphur-containing amino acids and inorganic forms of sulphur modify the pattern of sulphate metabolism. Methionine and thiosulphate sulphur are metabolised in preference to sulphate sulphur. A sulphur-containing cell-wall protein is involved in the cell division of mycelial yeasts. Division is accompanied by reduction of disulphide bonds in the compound. The rise and fall of the sulphur content of the fungus cells may be explained by the initial concentration of this substance in the cell wall prior to cell division and its subsequent reduction to a freely diffusable compound which is lost from the cell when growth begins.
79
The Relationship of Bivalent Cation Uptake to P o t a s s i u m and P h o s p h a t e Uptake in Yeast. A. ROTHSTEIN an d A. HAYES, Division of P h a r m a c o l o g y , D e p a r t m e n t o f R a d i a t i o n Biology, U n i v e r s i t y of R o c h e s t e r School of M e d i c i n e a n d Dentistry, Rochester, N e w York, U . S . A . Studies with Ca 45, Sr 9°, Mn 54 and p32 indicate that bivalent cations, although they are reversibly bound by the surface of the cell (RoxHSTEIN and HAYES, Arch. Biochem. 63, 87, 1956) are not absorbed into the cytoplasm unless there is a concomitant uptake of phosphate, associated with the metabolism of sugars. In contrast to the surface binding of cations which is relatively non-specific, the uptake with phosphate is highly specific for Mg ++ and Mn ++. However, other bivalent cations although only absorbed slowly
Radioactive I s o t o p e s in the S t u d y o f S y n t h e s i s P r o c e s s e s in Yeast O r g a n i s m s . R. D. GALTSOVA a n d N. A. POMOSHMKOVA, U.S.S.R. The study of regularities in the biosynthesis of protein and the influence on it of vitamins, amino acids and other organic compounds is simplified by the use of radioactive isotopes, the latter being particularly advantageous in biochemical and selection investigations. In our work, labelled compounds were used in conjunction with chromatographic methods of separating substances. In addition, special microbiological isotope techniques were worked out to speed up a determination of vitamins in the medium. A quantitative determination by these methods of pantothenic acid and pyridoxine is accomplished in accordance with the speed with which pa2 enters the indicator cultures and takes 4~6 hr, whereas the ordinary microbiological methods require from 40 48 hr. For pantothenic acid the method gives reproducible results in the case of a vitamin content of from 0.001 to 0.01 # per ml of medium; in the determination of pyridoxine, from %001 to 0.03 # of vitamin per ml of medium. Our investigations conducted with the aforementioned methods showed that vitamins and amino acids produce an essential influence on the biosynthesis of sulphur-containing amino acids and their inclusion in the protein. If pyridoxine is added to a culture medium which contains a labelled sulphate, the radioactivity is raised by 25 per cent; addition of thiamine or inosite raises absorption of the sulphate 15 per cent; biotin and nicotinic acid do not produce any influence on the inclusion of sulphur; pantothenic acid reduces the rate of absorption of Sas. If pyridoxine, biotin and thiamine are added to the medium simultaneously, the radioactivity of the yeast protein rises 35 per cent. When asparagine or asparaginic acid is added to the culture medium with S35, the radioactivity of the protein increases 25 per cent; glutamic acid does not produce any influence on the rate of absorption of a sulphate; alanine raises the rate of absorption by 15 per cent. The use of radioactive isotopes made it possible to establish the influence of vitamins and amino acids on the synthesis of protein not only in the case of auxoheterotrophic but in auxoautotrophic microorganisms as well.
209 78
S u l p h u r M e t a b o l i s m in Fungi.
JUNE E.
ROBSON, Isotope Division, A . E . R . E . H a r w e l l , U.K. Summary. Rhythmic rises and falls in the sulphur content of growing cells of Eremothecium Ashbyii, Aspergillus niger and Candida albicans have been demonstrated in a synthetic medium containing S35-1abelled sodium sulphate as the sole source of sulphur. In E. Ashbyii, Sa5 concentrates initially in the cell wall and then in the protoplasm until the sulphur distribution is equal. Growth then begins and the amount of sulphur in the hyphae drops rapidly. When growth has ceased a small quantity of sulphur remains in the cell wall. Changes in the S35 content are complemented by similar changes in the medium. Sulphate is metabolized extracellularly into at least five different compounds some of which disappear before growth begins; others appear when ,growth is taking place. Amino acids, sulphur-containing amino acids and inorganic forms of sulphur modify the pattern of sulphate metabolism. Methionine and thiosulphate sulphur are metabolised in preference to sulphate sulphur. A sulphur-containing cell-wall protein is involved in the cell division of mycelial yeasts. Division is accompanied by reduction of disulphide bonds in the compound. The rise and fall of the sulphur content of the fungus cells may be explained by the initial concentration of this substance in the cell wall prior to cell division and its subsequent reduction to a freely diffusable compound which is lost from the cell when growth begins.
79
The Relationship of Bivalent Cation Uptake to P o t a s s i u m and P h o s p h a t e Uptake in Yeast. A. ROTHSTEIN an d A. HAYES, Division of P h a r m a c o l o g y , D e p a r t m e n t o f R a d i a t i o n Biology, U n i v e r s i t y of R o c h e s t e r School of M e d i c i n e a n d Dentistry, Rochester, N e w York, U . S . A . Studies with Ca 45, Sr 9°, Mn 54 and p32 indicate that bivalent cations, although they are reversibly bound by the surface of the cell (RoxHSTEIN and HAYES, Arch. Biochem. 63, 87, 1956) are not absorbed into the cytoplasm unless there is a concomitant uptake of phosphate, associated with the metabolism of sugars. In contrast to the surface binding of cations which is relatively non-specific, the uptake with phosphate is highly specific for Mg ++ and Mn ++. However, other bivalent cations although only absorbed slowly