Standardization of "exchange" techniques to measure estradiol receptors in extracts exposed to biospecific adsorbants]

The measurement of the binding of steroid hormone receptors to biospecific adsorbants requires the development of "exchange" techniques. Two types of techniques based on the principle of differential dissociation were standardized: solid phase exchange with hydroxylapatite and liquid phase exchange with adsorption of the ligand to charcoal dextran. In both cases, binding of oestradiol to its receptor was measured in calf uterine cytosol extracts. Results obtained by both techniques were comparable. The half-times of the oestradiol-receptor complex dissociation determined from exchange kinetics are on the same order as those obtained by direct methods used in previous studies.     

The absence of an inhibitory effect of metyrapone (2-methyl-1,2-di (3-pyridyl) propan-1-one) on hepatic microsomal hydroxylation in scurvy.

Microsomes from livers of scorbutic guinea-pigs showed a reduced rate of acetanilide hydroxylation. The response of "scorbutic" liver microsomes to the inhibitor Metyrapone (2-methyl-1,2 di (3-pyridyl) propan-1-one) was different from that of liver microsomes from non-scorbutic guinea-pigs.     

Nuclear pores in the spermatozoon of the rat

Summary The paper describes a hexagonal array of nuclear pores in a non-redundant region of the nuclear envelope underlying the basal surface of the rat spermatozoon head. It is concluded that intranuclear material protruding through these pores is the cause of the characteristic rows of circular bumps found in surface replicas of this region.     

The suppression of mouse spontaneous locomotor activity by the ingestion of deuterium oxide.

The spontaneous locomotor activity of the laboratory mouse is significantly depressed by the ingestion of deuterium oxide. The response, which is reversible, is a retilinear one with up to 70% reduction in activity with the administration of 25% heavy water.     

Beta-adrenergic receptors in rat myocardium: Direct detection by a new fluorescent beta-blocker

Summary A new fluorescent -blocker, 9-amino-acridin propranolol (9-AAP), was administered i.v. to rats. Multiple fluorescent 9-AAP binding sites were observed on cardiac muscle cells in frozen sections. Intensity and density of cardiac 9-AAP fluorescence were markedly reduced following pretreatment with (±)- and (–)-propranolol but not with (+)-propranolol. Our findings suggest that 9-AAP may label -adrenergic receptor sites in rat myocardium.D. A. is supported by a fellowship from the Lady Davis Fellowship Trust and by a Research Grant from the Bat-Sheva de Rothschild Fund for The Advancement of Science and Technology. The technical assistance ofA. Itzhak is gratefully acknowledged.     

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.