Action of estrogens on reconstituted nucleohistones

The action of estrone, 17-estradiol, and estriol on the degree of binding of histones with DNA in reconstituted nucleohistones and the effect of these hormones on thermal denaturation of nucleoproteins were studied. Estrogens in concentrations of 10^–5 M were shown not to change the protein/DNA ratio by weight in partially reconstituted F₁, F_2a, F_2b, and F₃ nucleohistones and in total nucleohistone reconstituted from DNA and an equimolar complex of histones F_2a, F_2b, and F₃. Treatment with estrogens in the above-mentioned concentration does not change the melting point of any of the nucleohistones studied. The effect of estrogens on thermal denaturation of total nucleohistone and of partially reconstituted nucleohistones F_2a, F_2b, and F₃ consists of an increase in the hyperchromic effect of the first phase of melting and a corresponding decrease in the hyperchromic effect of the other phases. Estrogens did not change the thermal denaturation profile of partially reconstituted nucleohistone F₁.Department of Molecular Pharmacology and Radiobiology, Medico-Biological Faculty, N. I. Pirogov Second Moscow Medical Institute. (Presented by Academician of the Academy of Medical Sciences of the USSR S. S. Debov.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 85, No. 4, pp. 416–419, April, 1978.     

Hematopoietic organs of mice after a single injection oxyhydrocortisone

The method of exogenous cloning of hematopoietic stem cells (colony-forming units-CFU) in the spleen and bone marrow of lethally irradiated recipients was used to study the population kinetics and direction of differentiation of CFU from mice receiving a single dose (5 mg per mouse) of hydrocortisone. Against the background of prolonged involution of the lymphoid tissue changes took place in the population and differentiation of CFU. Meanwhile the CFU concentration in the spleen and femoral bone marrow of the mice remained constant. After administration of the hormone, the powers of differentiation of CFU from spleen and bone marrow changed sharply in opposite directions: Marrow CFU behaved like splenic CFU whereas splenic CFU behaved like marrow CFU of normal mice. It is suggested that these effects are due to redistribution of T lymphocytes and not to the direct cytotoxic action of hydrocortisone on the CFU population.Translated from Byulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 87, No. 1, pp. 16, January, 1979.     

Space flight effects on the skeletal muscles of rats.

Morphological and histochemical examinations of the skeletal muscles of rats flown for 22 d aboard the Cosmos-605 biosatellite have demonstrated atrophic and dystrophic developments in the soleus muscle accompanied by metabolic changes in the muscle tissue. The changes were reversible but did not disappear entirely 27 d postflight. Early atrophic developments were seen in the m. gastrocnemius, m. quadriceps, and m. ext. digitorum longus on the second postflight day. The comparative study of the muscles of flight and simulation rats has shown that pathology developed in the muscles as a result of diminished motor activity of animals being aggravated by weightlessness.