Role of lipids in theNeurospora crassa membrane |
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Authors: | Kenneth J Friedman |
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Affiliation: | (1) Laboratory of Physical Biology, National Institute of Arthritis, Metabolism, and Digestive Diseases, National Institutes of Health, 100 Bergen Street, 07103 Newark, New Jersey;(2) Present address: Department of Physiology, College of Medicine and Dentistry of New Jersey, New Jersey Medical School, 100 Bergen Street, 07103 Newark, New Jersey |
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Abstract: | Summary The effect of doubling the saturated fatty acid content on the electrophysiology ofNeurospora crassa membranes was studied. Intracellular membrane input resistance (R
m
) and potential (E
m
) were measured for wild-type (w/t) andcel
– (Tween 40) organisms as a function of temperature. Over the 0 to 40°C temperature range studied, meanE
m
values of bothw/t andcel
– (Tw 40) organisms increased from –160 to –210 mV. This difference is greater than that expected from Nernst potential considerations, indicating an active component ofE
m
. This active component is insensitive to a doubling of the saturated fatty acid content.R
m
exhibits a temperature dependence and hysteresis. Averaged data indicate an increase inR
m
with decreased temperature. The slope of the temperature dependence varies among individual hyphae. Above 17.5°Ccel
– (Tw 40) hyphae averaged greater than 70% higher values ofR
m
thanw/t. Below 17.5°Cw/t R
m
data divided into low and high temperature dependence groups, whilecel
– data exhibited a low temperature dependence. The results are discussed in relation to gel-liquid crystal phase transitions, membrane fluidity, and the contribution of fatty acid structure to membrane electrical properties. |
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Keywords: | |
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