Selective resistance to desiccation of nuclear ribonucleic acid synthesis in isolated nuclei of Artemia salina embryos during pre-emergence development.

The developing gastrula embryos of Artemia salina are resistant to a complete redesiccation during a period of pre-emergence development. Isolated nuclei from these dehydrated embryos could retain a transcriptional activity in vitro comparable with that of non-desiccated controls. On the other hand, redesiccation of both prenauplii and nauplii completely destroys their viability as well as the nuclear transcriptional activity. However, those gastrula embryos that did not develop in a first incubation period could remain viable and develop with a considerable time-lag after a subsequent second incubation

12-O-Tetradecanoylphorbol 13-acetate stimulates inositol lipid phosphorylation in intact human platelets

AbstractThe phorbol esters are among the most potent tumor promoters. On addition of 12-O-tetradecanoylphorbol 13-acetate (TPA) to isolated human platelets prelabelled with [32P]orthophosphate we found a rapid increase in 32P incorporation into phosphatidylinositol 4-phosphate and phosphatidylinositol 4,5-bisphosphate. In view of similar findings with cells infected with the oncogene Rous sarcoma virus, it is suggested that inositol lipid phosphorylation might be a key event in the molecular action of phorbol esters.PotyphosphoinositidePhorbol esterProtein kinase

Agents that elevate platelet cAMP stimulate the formation of phosphatidylinositol 4-phosphate in intact human platelets

AbstractThe present study investigates the effect of compounds that are known to elevate cAMP on the phospholipid metabolism of platelets. Prostaglandin E1, forskolin and isobutylmethylxanthine induce an increase in [32P]-phosphatidylinositol 4-phosphate (PIP) in platelets prelabelled with [32P]orthophosphate. Possible roles of this phenomenon are discussed in view of the inhibitory effect of cAMP elevation on platelet activation

Stimulation by serotonin of 40 kDa and 20 kDa protein phosphorylation in human platelets

AbstractIn human platelets, serotonin is known to induce a shape change followed by (reversible) aggregation. Recently, it was found that the amine triggers the elevation of cytosolic free calcium and activates phospholipase C. On stimulation of human platelets with serotonin we found an immediate increase in protein kinase C activity, phosphorylating its 40 kDa substrate protein. A 20 kDa protein, most likely the myosin light chain, was phosphorylated to the same extent. Ketanserin, a highly selective serotonin-S2 antagonist inhibited both phosphorylation processes at subnanomolar concentrations