Membrane composition and ion-permeability in extremophiles

Abstract: Protons and sodium ions are the only used coupling ions in energy transduction in Bacteria and Archaea. At their growth temperature, the permeability of the cytoplasmic membrane of thermophilic bacteria to protons is high as compared to sodium ions. In some thermophiles, therefore, sodium is the sole energy coupling ion. Comparison of the proton- and sodium permeability of the membranes of variety of bacterial and archaeal species that differ in their optimal growth temperature reveals that the permeation processes of protons and sodium ions must occur by different mechanisms. The proton permeability increases with the temperature, and has a comparable value for most species at their respective growth temperatures. The sodium permeability is lower than the proton permeability and increases also with the temperature, but is lipid independent. Therefore, it appears that for most bacteria the physical properties of the cytoplasmic membrane are optimised to ensure a low proton permeability at the respective growth temperature.     

The Combined Effects of Ethanol and Amphetamine Sulfate on Performance of Human Subjects

The combined effects of ethanol and amphetamine on the performance of selected tests were evaluated. No differences were shown between the effects of ethanol-amphetamine and ethanol-lactose on the performance of balance, skipping, Minnesota manipulation, Purdue peg board, Maudsley Personality Inventory, pursuit rotor or digit span tests; but ethanol plus amphetamine produced less impairment of performance of coding, mental addition, and trail making tests than did ethanol plus a placebo. Ethanol increased the errors in performance of the Wonderlic Personnel Test, but the simultaneous administration of amphetamine did not reduce this effect. Conversely, amphetamine reduced the test-retest reliability of the Wonderlic Personnel Test, but alcohol appeared to counteract this effect of amphetamine. These experiments indicate that, when ethanol and amphetamine are used together, each drug modifies some of the effects produced by the other in a manner that cannot be predicted on the assumption that a depressant versus stimulant competition is operative.