Membrane lipid metabolism in Acholeplasma laidlawii A during normal and temperature-shift-down conditions [proceedings].

solution, which prompted an immediate discharge from the cutaneous granular glands. The skin was then cut into small pieces and cultured in a nutrient/salts medium in a manner similar to that described by Baily (1971). One of the amino acids in the medium was replaced by the 3H-labelled amino acid. The skin cultures were incubated for up to 7 days at 28°C. After 3 and 7 days, samples of skin were first treated with an adrenaline solution, then dried in vacuo and extracted with methanol. The adrenaline solution, the methanol extract and the remaining medium were examined for the presence of jH-labelled caerulein. Thesampleswere mixed with an authentic sample of caerulein and examined by paper electrophoresis or paper chromatography. Samples from the adrenaline solution and the methanol extracts after 3 or 7 days incubation gave no radioactive peaks corresponding to the caerulein marker. However, samples of the medium in which the skins had incubated for 3 days gave a small peak of radioactivity which co-migrated with caerulein. When this solution was kept at 37°C over a period of several hours it was found that the amount of radioactivity which co-migrated with caerulein increased considerably. This suggests that caerulein matures during this period from a precursor molecule.