Cholesterol in mycoplasma membranes. Composition, ultrastructure and biological properties of membranes from Mycoplasma mycoides var. capri cells adapted to grow with low cholesterol concentrations

Rottem, Shlomo; Yashouv, Judith; Ne'eman, Zvi; Razin, Shmuel

doi:10.1016/0005-2736(73)90158-2

Cited by 148 publications

(42 citation statements)

References 27 publications

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“…The living cell can adapt to varying growth conditions by an alteration in the phospholipid and cholesterol content of its membrane, although other lipid components may well be important. The increase in the diglyceride content of cholesterol-depleted cells confirms the suggestion of Rottem et al (1973) that this is so. The diglyceride and monoglyceride spots on the thinlayer chromatograms could not be separated sufficiently for independent quantitative analyses to be performed.…”

Section: Discussionsupporting

confidence: 86%

“…In these studies, the only fatty acids present in the medium were oleic and palmitic. When the cholesterol content of the cells was reduced, the ratio of the saturated to unsaturated fatty acids in the cells increased, contributing to the maintenance of lipid fluidity in the membrane, a result in agreement with that reported by Rottem et al (1973). The precipitation of cholesterol by digitonin is well known (Moore & Baumann, 1952) and digitonin has been used to differentiate between Mycoplasmas and Acholeplasmas (Freundt et a/.…”

Section: Discussionsupporting

confidence: 79%

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Modification of the Membrane Composition of Mycoplasma mycoides subsp. capri by the Growth Medium

Archer¹

1975

Journal of General Microbiology

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S U M M A R YMycoplasma mycoides subsp. Capri was grown in different media. The amounts of the lipids in these media were varied, resulting in altered lipid compositions of the cells. Lowering the amounts of cholesterol in the media resulted in less cholesterol incorporation into the cell lipid, with a concomitant decrease in the amount of phospholipid. The changes in the phospholipid/cholesterol ratio in the mycoplasmas were very small compared with the large changes in the amount of cholesterol which occurred when the cholesterol content in the medium was altered. Changes in the amounts of glycolipid and glyceride in the cell lipid also resulted from alterations of the cholesterol concentration in the media. Under these conditions cells with reduced cholesterol contents were more sensitive to lysis by digitonin. No changes were observed in the polyacrylamide gel electrophoretic pattern of cellular or membrane proteins when the cholesterol was replaced by other sterols.

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Section: Discussionsupporting

confidence: 86%

Section: Discussionsupporting

confidence: 79%

Modification of the Membrane Composition of Mycoplasma mycoides subsp. capri by the Growth Medium

Archer¹

1975

Journal of General Microbiology

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“…This study provides the first evidence, however, that CLC treatment protects the bull and goat sperm when they are frozen directly from room temperature, without first cooling the sperm slowly to 5ºC. The cholesterol to phospholipid ratio is an important determinant of membrane fluidity and stability at low temperature (Ladbrooke et al, 1968;Rottem et al, 1973;Ohvo-Rekilä et al, 2002). Cholesterol modulates the fluidity of membranes by interacting with the fatty acyl chains of the phospholipids (Watson, 1981), keeping the phospholipids in a more fluid, lamellar arrangement as the temperature is reduced (Amann and Pickett, 1987).…”

mentioning

confidence: 88%

Effect of cholesterol-loaded cyclodextrins on bull and goat sperm processed with fast or slow cryopreservation protocols

Mocé

Tomás

Blanch

et al. 2014

Animal

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Cholesterol-loaded cyclodextrins (CLC) added to the sperm before cryopreservation enhance sperm quality after freeze-thawing in several cold shock-sensitive species, including cattle and goats. However, all studies conducted to date have used conventional protocols, in which sperm are cooled slowly to 5°C before freezing. As cholesterol plays a significant role in sperm cold shock resistance, it is possible that CLC-treated sperm can withstand cooling damage when the sperm are not cooled slowly to 5°C before freezing. In this study, we determined whether CLC-treated goat (1 mg CLC/120 × 10 6 sperm) and bull (2 mg CLC/120 × 10 6 sperm) sperm quality, after thawing, was different for sperm frozen using conventional protocols (including a slow cooling phase to 5ºC) and protocols in which the sperm were frozen from room temperature, without cooling the sperm slowly to 5°C before freezing. CLC-treated sperm exhibited higher percentages of plasma membrane-intact sperm than control sperm when cryopreserved using conventional protocols. In addition, CLC treatment enhanced both sperm motility and plasma membrane integrity when sperm were frozen directly from room temperature. However, this treatment did not fully prevent the damage of the sperm after cooling rapidly and subsequent freezing, as the sperm quality was lower than that presented by the samples frozen using the conventional protocol. The results are promising, but studies to optimize the protocols for freezing sperm directly from room temperature need to be conducted, as well as studies to determine how cryopreserving sperm in this manner affects other sperm functions.Keywords: cooling rate, semen, cattle, buck ImplicationsFreezing protocols for the semen of most of the species include a slow cooling phase to 5ºC. This phase requires from refrigeration units and comprises at least 85% of the total time cryopreserving sperm. In this study, we investigate whether treating bull and goat sperm with cholesterolloaded cyclodextrins allows eliminating this cooling phase. Our results show that this treatment partially prevents the damage to the sperm when directly frozen from room temperature and with this technique the sperm cryopreservation protocols are simplified, which would allow the processing of more ejaculates per day or freezing ejaculates collected in the field.

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“…In this way, B. acidocaldarius counteracted the fluidizing effects imposed on the cell membrane. Comparable adaptation strategies were reported for the sterol content in mycoplasma and some eukaryotic cells in response to changes in growth temperature (1,2,26,31). The total free-sterol content in S. cerevisiae also depended on the growth temperature when the yeast was grown under aerobic conditions in continuous culture (14).…”

mentioning

confidence: 93%

Content and composition of hopanoids in Zymomonas mobilis under various growth conditions

1991

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By using a new method for quantification of the different hopanoid derivatives, a total hopanoid content of about 30 mg/g (dry cell weight) was observed in Zymomonas mobiis. This value is the highest reported for bacteria so far. The major hopanoids in Z. mobiis were the ether and glycosidic derivatives of tetrahydroxybacteriohopane, constituting about 41 and 49% of the total hopanoids. Tetrahydroxybacteriohopane itself, diplopterol, and hopene made up about 6, 3, and 1%, respectively. Only minor changes in hopanoid composition were observed with changes in growth conditions. Earlier reports on a correlation between hopanoid content and ethanol concentration in the medium could not be confirmed. Over a wide range of ethanol concentrations (5 to 60 g/liter), growth rates (0.08 to 0.25 h-1), and temperatures (25 to 37C), the molar ratio of hopanoids to phospholipids in the cells amounted to about 0.7. Only at growth rates of >0.30 h-1 did the molar ratio increase to about 1.The gram-negative, obligately fermentative bacterium Zymomonas mobilis is well-known for its high specific rates of ethanol production of up to 5 g of ethanol per g of dry cell weight per h. In continuous culture, Z. mobilis can accumulate up to 6% (wt/vol) ethanol, and in batch culture it can even accumulate up to 13%. Thus, its ethanol tolerance is remarkably high and comparable to that of yeasts (24).Several studies have indicated that ethanol decreases the degree of membrane organization, increases membrane leakage, and influences activities of membrane-associated proteins and transport systems (16,19). In ethanol-tolerant microorganisms, adaptation to ethanol stress involves an increase in the mean chain length of incorporated fatty acids, thereby thickening the hydrophobic membrane core. Often, the proportion of monounsaturated fatty acids (e.g., cisvaccenic acid) also increases (15). The extremely ethanoltolerant Lactobacillus homohiochii even incorporates over 97% unsaturated fatty acids in the membrane when growing in the presence of 10% (wt/vol) ethanol (15). Furthermore, sterols enhance the alcohol endurability of the cell membrane in yeasts, as was demonstrated with anaerobic cultures of Saccharomyces sake, which depended on supplementation with sterol ester to acquire ethanol tolerance (12).For Z. mobilis it was shown that more than 70% of the fatty acids in the phospholipid fraction is cis-vaccenic acid, which appears to be suitable for an ethanol-tolerant microorganism (7, 30). The most striking result, however, was the observation of considerable amounts of neutral hopanoids (6). Several different hopanoid derivatives were detected in Z. mobilis (10) (Fig. 1). Structural similarities to sterols, found in eukaryotic membranes, are apparent (20). Both classes of compounds are amphiphilic and have planar, rigid carbocyclic structures. Moreover, physicochemical studies on model membranes have shown that, like sterols, hopanoids influence membrane fluidity and stability (8,17,18).Recently a new method has been developed which enab...

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Cholesterol in mycoplasma membranes. Composition, ultrastructure and biological properties of membranes from Mycoplasma mycoides var. capri cells adapted to grow with low cholesterol concentrations

Cited by 148 publications

References 27 publications

Modification of the Membrane Composition of Mycoplasma mycoides subsp. capri by the Growth Medium

Modification of the Membrane Composition of Mycoplasma mycoides subsp. capri by the Growth Medium

Effect of cholesterol-loaded cyclodextrins on bull and goat sperm processed with fast or slow cryopreservation protocols

Content and composition of hopanoids in Zymomonas mobilis under various growth conditions

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