Alteration in phospholipid composition of Staphylococcus aureus during formation of autoplast

The phospholipid composition of autoplasts (protoplasts made by autolysis of Staphylococcus aureus 209P was examined. The autoplasts were prepared by incubation of 209P cells in 1.2 M sucrose--0.33 M acetate buffer (pH 5.8). Cardiolipin comprised nearly half the total phospholipid in these autoplasts. Autoplasts had a lower phosphatidylglycerol content than intact cells but similar lysylphosphatidylglycerol content. The increase in cardiolipin content during release of autoplasts was not affected by pH or temperature. The result indicates that removal of the cell wall caused the increase in cardiolipin content. The total amount of phospholipids increased slightly during autoplast formation, but there was no significant increase in fatty acids or diglycerides. The changes of phospholipid composition during formation of the autoplast was due to de novo synthesis of cardiolipin from phosphatidylglycerol.

Stable state conditions of population-dependent migration models under a zero natural growth rate

The author "attempts to examine the stable conditions of regional population under a zero natural growth rate in the context of a certain general class of [population-dependent] nonlinear migration models." Theorems regarding the stable state conditions of the migration models are presented. The parameters of the gravity migration model are then estimated empirically using data on Japanese inter-prefectural migration flows in 1966, 1970, and 1975. The possibility of achieving the stable state in Japan is discussed

Presence and synthesis of cholesterol in stable staphylococcal L-forms

The sterol which was present in two strains of a stable staphylococcal L-form was analyzed by gas-liquid chromatography and combined gas-liquid chromatography-mass spectrometry. The retention time of the sterol on gas-liquid chromatography was the same as that of authentic cholesterol. Analysis of the sterol by mass spectrometry showed a molecular ion at an m/e of 386 and the same patterns of major ions above an m/e of 145 as those of authentic cholesterol. As a result, the sterol in staphylococcal L-form was identified as cholesterol. A parent strain and its L-forms were cultured in medium containing [14C]acetate, and the synthesis of cholesterol was examined. In the L-forms, 0.52% of the total lipid radioactivity was found in cholesterol fraction, whereas no significant radioactivity was detected in the cholesterol fraction of the parent strain, indicating that staphylococcal L-forms have acquired the capacity to synthesize cholesterol.

Lipid composition of Staphylococcus aureus and its derived L-forms

Two strains of Staphylococcus aureus (Newman and Tazaki) and their derived L-forms were cultured in serum-containing broth and the differences in their lipid compositions were analyzed. Cardiolipin accounted for more than 50% of the total phospholipid phosphorus in L-forms, but for less than 25% in parent bacteria. The cardiolipin content of L-forms was very high through all growth phases, although it increased gradually as growth proceeded. Significant amounts of cholesterol and its esters were present in parent strains and L-forms, all of which incorporated serum cholesterol into the cell membrane. On the other hand, they could be detected in the L-forms but not in the parent strains when they were cultured in serum-free broth. To examine the ability of L-forms to synthesize cholesterol, the cholesterol content of L-forms cultured in serum-free broth was compared with that of the medium. The results indicated that staphylococcal L-forms could synthesize cholesterol and its esters. These differences in lipid composition suggested that modification of membrane lipids may occur as an adaptational change in response to the disappearance of the cell wall.

Population dynamics of cities in a region: conditions for a state of simultaneous growth

This paper first proposes a nonlinear dynamic migration model that describes the population dynamics of cities in a region. Second, by use of this model, several theorems are proved about the conditions necessary for (1) a state of simultaneous growth (that is, when the population of every city in a region increases simultaneously), and (2) a state of proportional growth (that is, when every city's proportion of the total population remains the same over time). Third, based upon the data analysis of interprefectural migration flows in Japan in 1970, some empirical implications of these theorems are considered.

Adaptational change in proline and water content of Staphylococcus aureus after alteration of environmental salt concentration

Adaptation of Staphylococcus aureus to a change in salinity was studied by estimating the intracellular content of water and proline after alteration of the salt concentration of the culture medium. The intracellular water content of S. aureus cultured in normal broth was 1.70 g/g (dry weight). After transfer to 1.8 M NaCl-containing broth, the water content decreased to 0.80 g/g (dry weight) within 1 min. After changing the salt concentration of the medium, intracellular free proline (assumed to be one of the osmoregulators in S. aureus) increased gradually from 0 to 1,400 mumol/g (dry weight) during 30 min of incubation at 37 degrees C. The water content rose to 0.88 g/g (dry weight) in 30 min. Proline was not taken up at 0 to 4 degrees C, suggesting that the process was one of active transport. The salt tolerance of S. aureus, therefore, appears to occur initially by dehydration of the cell after transfer from a medium of low salinity to one of high salinity and then by accumulation of proline, which carries water into the cell with it.

A method for microdetermination of major neutral lipids and an application of the procedure to tissue lipids

Cholesterol, cholesteryl esters, triglycerides and fatty acids as major neutral lipids and phospholipids were examined in quantitative analysis. The method consisted of three steps: (1) separation of lipids by one-dimensional thin-layer chromatography on silica gel plates; (2) elution of neutral lipids from scraped silica gel with chloroform-methanol (4:1); and (3) colorimetric determination of individual neutral lipids in eluates and phospholipids in silica gel. The conditions were modified for chromotropic acid reaction for determining triglycerides. Laurell's method for determining fatty acids was also modified to apply to quantitative thin-layer chromatography. The accuracy of the modified methods was well-defined as the absorbance values were on a linear curve. A quantitative study was made of the recovery of triglycerides and fatty acids after chromatography. Combining these modified methods and colorimetry for determination of cholesterol cholesteryl esters and phospholipids, the author established a micromethod for determining the major neutral lipids and phospholipids by thin-layer chromatography. Lipids from HeLa, S-3 cells were analyzed to examine the applicability of this method to tissues. The results indicated that the new method permitted a reliable estimation of the major neutral lipids and phospholipids from small amounts of tissues.