Effects of chronic treatment with ACTH on the intracellular levels of cyclic-AMP and cyclic-GMP in the rat adrenal cortex.

The effects of chronic ACTH treatment on the increase in the intracellular concentration of cyclic-AMP and cyclic-GMP acutely elicited by ACTH in the rat adrenal cortex were investigated. The results are consistent with the hypothesis that chronic ACTH treatment stimulates a) the de novo synthesis of adenylate- and guanylate-cyclase or b) the synthesis of new specific membrane receptors for ACTH.     

Criteria for the appearance of post-tetanic potentiation of transmission at central synapses in Helix aspersa.

Long-lasting potentiation of inhibitory post-synaptic potentials occurs at 2 identifiable synapses in Helix brain. It appears only after tetanic stimulation and after a minimum of 20 impulses. Its amplitude and duration depends on the number of stimuli.     

Further characterization of the effects of ultraviolet irradiation of the amphibian egg

UV-irradiation of the vegetal hemisphere of amphibian eggs leads to developmental abnormalities in neural morphogenesis. The possibility that the egg's transient sensitivity to irradiation could be due to pigmentation changes was examined in albino eggs. The tissue specificity of the effects of irradiation was analyzed by exchanging the ectoderm between irradiated and control embryos.     

Metabolic studies of Hg-203 on Chlamydomonas reinhardi

Sterile cultures of Chlamydomonas reinhardi, WT+, were treated with Hg-203 at 25 degrees C to identify probably formed volatile mercury compounds. Experiments were performed with living and dead cells under aerobic or anaerobic conditions, respectively, and the mercury concentration was measured in the system algae/nutrient medium. We found a timerelated decrease of mercury concentration in the cell suspension and the cell-free nutrient medium due to a reduction of Hg++ to Hg0, probably caused by extracellular enzymes; monomethyl or dimethyl mercury could not be detected.     

G-6PD loading of G-6PD-deficient erythrocytes

G-6PD-deficient erythrocytes were loaded during hypotonic hemolysis with G-6PD extracted from yeast. It was shown that enzyme was really trapped into red blood cells and remained functionally active.