Conservation of cytoplasmic poly (A)-containing RNA in mouse and rat.

By comparing the melting temperature of DNA-DNA duplexes between related species, it is shown that total single-copy DNA evolves at a faster rate that DNA which is transcribed into poly (A)-containing RNA. Such a comparison suggests that at least 70% of rat single-copy DNA does not code for protein.     

The structural relationship of phorbol and cortisol: A possible mechanism for the tumor promoting activity of phorbol

Summary The crucial functional groups of phorbol-12-myristate-13-acetate (PMA) are superimposable with those of the glucocorticoid cortisol in a unique manner which suggests a mechanism for PMA activity, i.e. the alkylation of a cortisol receptor.     

Structural changes of deoxyribonucleoprotein fibres following gamma-irradiation under aerobic and hypoxic conditions.

The DNP fibres gamma-irradiated under aerobic condition showed a reduction of their diameter, while no remarkable changes were observed in the DNP fibres irradiated under hypoxic condition by scanning electron microscopy.     

Effect of heat treatment on the ATPase activity of various sarcoplasmic reticulum preparations.

Ca2+-stimulated ATPase activity of sarcoplasmic reticulum (SR) preparations is activated after a short period of preincubation at temperatures between 40 and 45 degrees C, but for temperatures higher than 48 degrees C pronounced denaturation is observed. Heat denaturation is decreased if Mg2+ or K+ are present during heat treatment.     

Effect of X-537A on the phosphorylated protein in sarcoplasmic reticulum vesicles

Summary The effect of the antibiotic X-537A on the phosphorylated ATPase (EP) was investigated. The results show that X-537A depresses the level of EP which is dependent on the Ca²⁺ gradient, while the Ca²⁺-independent EP is not affected. Acknowledgments. This work was supported by grants from the Instituto de Alta Cultura of the Portuguese Ministry of Education (No. CB/2) and the Calouste Gulbenkian Foundation.     

Regulation of enzymes of ethanol metabolism in yeast (Rhodotorula gracilis)

Summary The three enzymes of ethanol metabolism alcohol dehydrogenase, aldehyde dehydrogenase and acetyl-CoA synthetase in the obligate aerobic yeastRhodotorula gracilis are repressed by glucose and induced by C₂ metabolic fuels with a regulatory pattern indicating a correlation in the control mechanisms. To try an identification of the molecular signals involved in the transmission of the inducing stimulus, experiments were carried out by blocking with 2 mM pyrazole the ethanol acetaldehyde metabolic step. Results indicate that ethanol is not specifically required as a molecular signal for induction.This work was supported by a grant from the Italian Consiglio Nazionale delle Ricerche.