Control of membrane lipid fluidity in <i>Acholeplasma laidlawii</i>

Huang, Leaf; Lorch, Steven K.; Smith, Gary G.; Haug, A.

doi:10.1016/0014-5793(74)81090-2

Cited by 45 publications

(8 citation statements)

References 19 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The narrow thermal response range is consistent with the possibility that the thermotransducer is a specific substance or structure (e.g., a protein or a lipid) that undergoes a phase transition over a relatively narrow temperature range. The phenomenon of thermal adaptation supports the hypothesis that the substance is a lipid in a membrane matrix, because only the lipid components in membranes have been shown to exhibit such temperature adaptation (15)(16)(17).…”

Section: Discussionsupporting

confidence: 73%

Thermotaxis by pseudoplasmodia of Dictyostelium discoideum.

Poff¹,

Skokut²

1977

Proc. Natl. Acad. Sci. U.S.A.

View full text Add to dashboard Cite

The temperature dependence of migration rate and of the thermotactic sensitivity of pseudoplasmodia of Dictyostelium discoideum has been measured. Migration Amoebae of the cellular slime mold Dictyostelium discoideum aggregate to form pseudoplasmodia which contain 103-105 cells surrounded by a slime sheath, and which can migrate under suitable conditions for up to 10 cm before forming fruiting bodies (1). Migrating pseudoplasmodia are positively phototactic and positively thermotactic (2). Although phototactic migration in D. discoideum has recently received considerable attention (3-6) the thermotactic response of the organism has not been studied since the original observation of thermotaxis by Bonner (2). One can easily visualize a specific biological response to light that is absorbed by a specific photoreceptor pigment. In contrast, the absorption of heat is inherently nonspecific. Nevertheless, an absorption of heat must precede the specific biological response of thermotaxis. The purpose of this study was to examine the mechanism whereby pseudoplasmodia of D. discoideum respond to thermal gradients. MATERIALS AND METHODSDictyostelium discoideum strain NC-4 was used in most experiments. Cells were grown in association with Klebsiella aerogenes for 48 hr as described by Sussman (7). The cells were then harvested and freed of bacteria by washing three times with a salt solution described by Bonner (8) and suspended in a phosphate buffer solution at 108 cells per ml (7). A 10 Al drop of cells was deposited in the center of a petri dish containing sterile, nonnutrient aqueous agar (2% wt/vol). After 15-16 hr incubation at 23.50 in darkness, aggregation had proceeded with the formation of migrating pseudoplasmodia. Alternatively, in a few experiments, D. discoideum strains Ax-2, and L-25 (4) were used. Strain L-25 was cultured in the same manner as strain NC-4, while strain Ax-2 was cultured axenically in liquid shake culture in a medium containing 10 g of glucose, 5 g of Difco yeast extract, and 10 g of Baltimore Biological Laboratories trypticase in 1000 ml of 2 mM potassium phosphate buffer at pH 6.5. Exponentially growing Ax-2 cells were collected by centrifugation, washed, and deposited on nonnutrient agar as above.Temperatures were measured with a Yellow Springs Instrument Co. Tele-thermometer with a 5 mm diameter contact thermistor probe, a copper-constantan thermocouple in conjunction with a microvolt meter, or with a precision mercuryin-glass thermometer. The incubation temperature for cultures in petri dishes was controlled by placing the dishes on a 2.5 cm X 11 cm X 36 cm aluminum block with recesses for the dishes and with holes bored lengthwise through each side of the block (Fig. 1). Water from a constant-temperature water bath was circulated through each side of the block; the latter was surrounded by a minimum of 10 cm of styrofoam and placed in a dark room. The temperature of each side of the petri dish could be varied from 120 to 350 and was constant to ±0.050 for 24 hr. Temperature...

show abstract

Section: Discussionsupporting

confidence: 73%

Thermotaxis by pseudoplasmodia of Dictyostelium discoideum.

Poff¹,

Skokut²

1977

Proc. Natl. Acad. Sci. U.S.A.

View full text Add to dashboard Cite

show abstract

“…In fact, Rottem et al (268) showed that decreasing the growth temperature of A. laidlawii to 15°C caused a significant increase in the amount of exogenous oleic acid incorporated into membrane lipids. Membranes of A. laidlawii grown in the cold (15 or 28°C) were more fluid than membranes of cells grown at 370C when compared at the same temperature (133,137,200,268), a finding pointing in the same direction. Nevertheless, a significant shifting down in the growth temperature of A. laidlawii brought about only minor alterations in the pattern of fatty acids derived from de novo synthesis or chain elongation (279), resulting in only a slight decrease in the average chain length of the fatty acids of membrane lipids (174).…”

Section: Regulation Of Membrane Fluidity Inmentioning

confidence: 73%

The mycoplasmas.

Razin¹

1978

Microbiological Reviews

218

135

View full text Add to dashboard Cite

show abstract

“…There is evidence in the literature that various cells types are able to regulate phospholipid fatty acid composition so that membrane viscosity remains constant (Huang, Lorch, Smith & Haug, 1974;Sinensky, 1974;Miller, Hill & Smith, 1976). Although this homeoviscous response is usually thought of as an adaptation mainly of poikilotherms to changes in environmental temperature, its counterpart in mammalian cells may be the effort of such cells to maintain a relatively constant ratio of unsaturated to saturated fatty acids.…”

Section: Discussionmentioning

confidence: 99%

Uptake of arachidonic acid into membrane phospholipids: Effect on chloride transport across cornea

et al. 1982

View full text Add to dashboard Cite

We demonstrate that arachidonic acid (AA) stimulation of chloride transport across frog cornea is mediated via two independent pathways: (1) stimulation of prostaglandins and cAMP synthesis, and (2) a direct physical change in the membrane produced by substitution of different phospholipid acyl chains. AA is well known as a precursor in the synthesis of prostaglandins, which have been shown to stimulate cAMP synthesis and chloride transport in frog cornea. We show that frog cornea can convert exogenous AA to PGE2, but that in the presence of 10(-5) M indomethacin both the conversion to PGE2 and stimulation of cAMP are completely blocked. However, with indomethacin the action of AA to stimulate chloride transport (as measured by SCC) remains, but peak height of the response is reduced to 57% of that found when AA alone is given. Similarly, we show that propranolol completely blocks cAMP stimulation, but stimulation of SCC is reduced to 45% of the original response. Therefore, cAMP appears to be responsible for roughly half of the observed stimulation in SCC. By gas chromatographic analysis we show that significant quantities of AA can rapidly substitute into membrane phospholipids of corneal epithelium and L929 cells following the addition of AA to the medium. Modification of membrane phospholipid structure can affect membrane viscosity, membrane-bound enzyme activity, and the distribution and lateral mobility of integral proteins. It seems likely that such alterations in the properties of the membrane may modulate the rate of chloride transport, and this may constitute the second mechanism. Upon addition of AA, both mechanisms appear to stimulate chloride transport simultaneously, and are apparently additive. We show that prolonged exposure to AA results in a large incorporation of AA into phospholipid and consequently, a perturbation in the ratio of unsaturated to saturated fatty acids. We also find evidence of a compensatory cellular mechanism that alters the ratio of endogenously synthesized fatty acids and tends to reduce the membrane-perturbing effect of AA.U

show abstract

Control of membrane lipid fluidity in Acholeplasma laidlawii

Cited by 45 publications

References 19 publications

Thermotaxis by pseudoplasmodia of Dictyostelium discoideum.

Thermotaxis by pseudoplasmodia of Dictyostelium discoideum.

The mycoplasmas.

Uptake of arachidonic acid into membrane phospholipids: Effect on chloride transport across cornea

Contact Info

Product

Resources

About