Effects of low-temperature stress on the metabolism of phosphatidylglycerol molecular species in Dunaliella salina.

A detailed analysis was made of individual phosphatidylglycerol (PG) molecular species isolated from microsomes and chloroplasts at various times after labeling Dunaliella salina cells with [14C]palmitic, [14C]oleic, or [14C]lauric acid. The patterns of [14C]fatty acid incorporation were in agreement with PG being formed by the "eucaryotic" type pathway in microsomes and the "procaryotic" type pathway in chloroplasts. In Dunaliella, which lacks a quantitatively significant flux of eucaryotic-type lipids from microsomes into chloroplast glycolipids, indications were found for a more subtle movement of microsomally synthesized PG into the chloroplasts. This transfer was more evident in cells stressed by exposure to 12 degrees C than it was at 30 degrees C, and may afford a mechanism for recruiting key microsomal PG molecular species toward low-temperature acclimation in chloroplasts.