Reconstitution of the Turkey erythrocyte adenylate cyclase sensitivity to l-epinephrine upon re-insertion of the Lubrol solubilized components into phospholipid vesicles

Turkey erythrocyte adenylate cyclase was activated by GppNHp and l-epinephrine to its stable, highly active form. In this form the enzyme could be solubilized by Lubrol-PX and subsequently re-inserted into phospholipid vesicles concomitantly with the removal of up to 99.3% of the Lubrol. The ability of GTP and l-epinephrine to reverse the GppNHp/epinephrine activated state was taken as a measure for the reappearance of hormone sensitivity in the reconstituted vesicles. An incomplete but significant reappearance of hormone sensitivity in the reconstituted adenylate cyclase was achieved. This hormone sensitivity was found to be stereospecific for (?)epinephrine. The ¹²⁵I-cyanopindolol binding properties of the reconstituted β-receptor depend on the nature of the detergent and the phospholipids used in the reconstitution.     

Separation and identification of O-acetyl-O-methyl-galactononitriles by gas-liquid chromatography and mass spectrometry

The gas-liquid-chromatographic retention-times and the mass-spectral features of partially methylated d-galactononitrile acetates are reported. Distinctive fragmentation of each of the mono-O-methyl derivatives allows their identification, and the results are applicable to the same substituted derivatives of the other aldohexoses. A new fragmentation-pathway, typical of the acetylated and the O-acetyl-O-methylaldononitriles, is proposed in order to justify previously unexplained fragments. This fragmentation competes with the known ones in derivatives that do not carry vicinal methoxyl groups.     

Supranucleosomal organization of chromatin

A systematic study of the effect of different ionic conditions on the morphology of the 25–30 nm chromatin fiber from chicken erythrocytes has revealed that, as the ionic strength is increased, knobby fibers with a clear superbead structure are formed in the presence of either Mg⁺⁺ or Na⁺, or both. A further increase in ionic strength results in smooth chromatin fibers due to a tight packing of superbeads. Cross-linking such fibers with formaldehyde and reversal of the ionic conditions, demonstrates the superbead structures underlying the smooth fibers observed at high ionic concentrations. The average size of the superbeads is 34 nm along the length of the fibers, in agreement with the value found in embedded sea cucumber chromatin. A second class of superbeads has an average length of 25 nm and probably corresponds to partially disrupted structures.     

Foliicole Flechten aus der Kolchis (West-Transkaukasien,UdSSR)

This paper deals with 19 species of foliicolous lichens collected in the summer months of 1977 to 1980 during several excursions to the vicinity of the spas Sochi, Gagra and Sukhumi on the east shores of the Black Sea (part of the Colchis). Some new taxa and one new combination are proposed:Raciborskiella minor Vězda (sp. n.),Porina colchica Vězda (sp. n.),Gyalectidium caucasicum (Elenk. etWoronich.)Vězda (comb. n.),G. colchicum Vězda (sp. n.),Bacidia vasakii Vězda (sp. n.). Taxonomical, ecological and plant geographical notes to all species are given.     

Toxic effects of ochratoxin A and citrinin, alone and in combination, on chicken embryos

The embryotoxic potential of ochratoxin A and citrinin was studied after administering, either subgerminally or intraamniotically, single mounting doses of the mycotoxins to chicken embryos on days 2, 3, and 4. The beginning of the embryotoxicity dose range was found to be between 0.01 to 0.05 microgram for ochratoxin A and 1 to 10 micrograms for citrinin. The maximum response to both mycotoxins occurred after administration on day 3. In addition to significant growth retardation of fetuses, exencephaly, microphthalmia, cleft beak, reduction deformities of the limbs, and abdominal wall and ventricular septal defects were encountered on day 8 of incubation. When 4 micrograms of citrinin was constantly added to ochratoxin A administered in the dose range of 0.03 to 0.5 microgram, a strictly additive effect was seen. It may be supposed that citrinin produced together with ochratoxin A in some strains of Penicillium viridicatum Westling does not potentiate the clear-cut embryotoxic action of the latter mycotoxin.     

Effect of streptozotocin diabetes on some urea cycle enzymes

Streptozotocin induced diabetes in rats increased the activities of the three mitochondrial enzymes, carbamylphosphate synthetase, ornithine transcarbamylase and N-acetylglutamate synthetase, but not of the cytosolic N-acetylglutamate deacylase. Levels of both N-acetylglutamate and arginine, which are activators of carbamylphosphate synthetase and N-acetylglutamate synthetase respectively, increased in diabetes. These results serve to explain the increase both of mitochondrial citrulline and urea formation in hepatocytes and the increased urea excretion in diabetes.     

Ca2+-dependent K+ transport in the Ehrlich ascites tumor cell

The possible presence and properties of the Ca2+-dependent K+ channel have been investigated in the Ehrlich ascites tumor cell. The treatment with ionophore A23187 + CA2+, propranolol or the electron donor system ascorbate-phenazine methosulphate, all of which activate that transport system in the human erythrocyte, produces in the Ehrlich cell a net loss of K+ (balanced by the uptake of Na+) and a stimulation of both the influx and the efflux of 86Rb. These effects were antagonized by quinine, a known inhibitor of the Ca2+-dependent K+ channel in other cell systems, and by the addition of EGTA to the incubation medium. Ouabain did not have an inhibitory effect. These results suggests that the Ehrlich cell possesses a Ca2+-dependent K+ channel whose characteristics are similar to those described in other cell systems.     

Hormonal control of casein synthesis in mammary explants from pregnant goats

The effects of insulin, cortisol, prolactin, 3,3',5-triiodo-L-thyronine (L-T3) and progesterone on the synthesis of total protein and casein in mammary explants from pregnant goats were studied. In the absence of hormones and in the presence of insulin plus cortisol the rate of incorporation of 14C-leucine into proteins that were precipitated with the anti-casein antibody decreased during culture. The addition of prolactin to hormonal combination of insulin and cortisol caused large stimulation of rates of casein synthesis. Maximum incorporation of leucine was attained between 3 and 5 days of culture in the presence of 0.5 microgram ml-1 of prolactin. Prolactin stimulated-casein and total protein synthesis were not consistently affected by the addition of L-T3 or progesterone. The inhibition of DNA synthesis by hydroxyurea or cytosine-arabinofuranoside had no effect on casein synthesis in mammary explants from pregnant goats.