Alterations of beta-adrenoceptor-density and cAMP-synthesis in rat-erythrocytes after stress erythropoiesis.

During the maturation of red blood cells from rats after stress erythropoiesis, adenyl cyclase activity and beta-adrenoceptor density (pmoles/mg protein) decrease at distinctly different rates suggesting a different turnover of these membrane units.     

Increase in Na+, K+ -ATPase enzyme units in liver and kidneys from essential fatty acid deficient rats.

(3H)-Ouabain binding to liver and kidney preparations was utilized to estimate the number of Na+, K+-ATPase enzyme units in livers and kidneys from rats fed 2% corn oil supplemented or fat-free diets. The specific (3H)-ouabain binding in liver and kidney preparations from fatty acid deficient rats was increased approximately 40%, but the affinity of the binding sites for ouabain (Kd-value) remained unchanged. The increased concentration of Na+, K+-ATPase enzyme units observed in the essential fatty acid deficient rats may contribute to the reduced body fat accumulation and elevated heat production observed in these animals.     

A rotating bottle culture method with continuous replacement of the gas phase

Summary A rotator culture method is described which provides a continuous flow of oxygenating gas to cultures in rotating bottles. The system maintains constant O₂ and CO₂ levels in the culture medium throughout the incubation period. It also provides a more stable pH than systems with sealed culture bottles.Acknowledgments. We would like to thank Mr B. Secker, Mr C. Hellon and Mr S. J. Ellis, of the Physiological Laboratory workshop, for constructing the rotator apparatus. We also thank the Medical Research Council, London, for financial support for the project.     

Monolayer cultures of perikarya isolated from postnatal rat cerebellum

Summary Viable cerebellar perikarya of mixed cell type obtained from 7–9-day-old rats were maintained in monolayer culture for up to 12 days. During this time extensive neurite formation and outgrowth occurred. The large majority of the cells developing in culture were tentatively identified as granule neurons. This identification was based on the large number isolated from the starting tissue, and the cells general morphological features in culture such as perikaryal and nuclear size, the bipolar nature of neurite extension, and their migratory behaviour.D.N. Currie was supported by a grant from Hoechst Pharmaceuticals, Ld, U.K.J.C. was supported by an S.R.C. Grant to S.P.R. RoseThe authors would like to thank Kathleen Tear for excellent technical assistance and members of the Brain Research Group for helpful discussions.     

0957 + 561 A, B: twin quasistellar objects or gravitational lens?

0957 + 561 A, B are two QSOs of mag 17 with 5.7 arc s separation at redshift 1.405. Their spectra leave little doubt that they are associated. Difficulties arise in describing them as two distinct objects and the possibility that they are two images of the same object formed by a gravitational lens is discussed.     

Density gradient centrifugation of cells separated from multicellular tumor spheroids

Summary Cells from a murine fibrosarcoma (FSa) have been grown in vitro as multicell tumor spheroids (MTS). The growth rate of these MTS was determined. Follwing selected periods of growth, MTS were made into a single cell suspension and separated on linear density gradients of Renografin. While only 1 population of cells was separated from small spheroids (400 m diameter), at least 3 subpopulations of tumor cells were separated and isolated from large spheroids (800 m in diameter).This investigation was supported in part by grants numbered CA-18628 and CA-06294, awarded by the National Cancer Institute, DHEW.     

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.     

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.