Preparation and oxygen binding properties of soluble covalent hemoglobin-dextran conjugates

Summary Stroma-free hemoglobin solutions present some drawbacks when used as blood substitutes, essentially because the hemoprotein has a low vascular retention, due to its small hydrodynamic volume. Covalent coupling of the protein with dextran derivatives artificially increases its size and affords polymeric conjugates whose oxygen-binding properties (Barcroft's curve, Hill coefficient) depend on the molecular weight.The authors wish to thank Prof. J. Neel and Prof. C. Vigneron for useful discussions and criticism.     

Action de l'orientation et de la qualité de la lumière sur le développement des protonémas de Bryales

Summary The radiations coming from Blanc Brillant de Luxe' fluorescent stimulate the growth and ramification of protonema ofCeratodon purpureus (Hedw.) Brid. This stimulation is caused by red light (660 nm). Multidirectional lightening is more favorable than unidirectional exposition.     

Non-mendelial female sterility in Drosophila melanogaster: demonstration of an inducer chromosome 4]

Crosses between two classes of Drosophila melanogaster strains (reactive and inducer) may lead to partially sterile F1 females. This sterility, called S.F. sterility, can be characterized by its physiological features. It appears to be the result of an interaction between two factors: "R" brought into the initial croos by the reactive mother and "I" by chromosomes of the inducer father. Except for chromosome 4, each chromosome of the well known inducer strains may carry the I factor (inducer chromosomes). The present results provide evidence for the presence of an inducer fourth chromosome in the inducer strain Nagasaki.     

Lithium exchange in from epithelium: determination of unidirectional flux using the stable isotopes 6Li and 7Li in an ionic analyzer]

The use of the stable isotopes 6 and 7 of lithium, and detection with the ionic analyser, allow the measurement of unidirectional transepithelial Li-fluxes, between "external" and "internal" solutions which both contain 80% Na and 20% Li. Efflux was found to be bigger than influx. An important lag-phase on the curve, reveals the interference of a Li-compartment, with a high capacity, in the epithelium itself.     

Transposable genetic elements as agents of gene instability and chromosomal rearrangements.

Transposable genetic elements in prokaryotes and eukaryotes, when inserted at a given locus, can control expression of the locus and cause large scale rearrangements of adjacent DNA sequences. Striking similarities in genetic behaviour between the two groups of elements have led to the proposal of a molecular model of eukaryotic controlling elements, and to suggestions about the part such elements may play in evolution and differentiation.     

Dissociation of glucocorticoid effects of C-21 steroids at high concentrations in thymocytes

Summary A dissociation between inhibition of RNA synthesis and cell lysis was observed when thymocytes of adrenalectomized rats were incubated with high concentrations of pregn-4-ene-11-ol-3, 20-dione and pregna-1,4-diene-11-ol-3,20-dione. In contrast, no dissociation of these effects was found with the typical glucocorticoids cortisol and corticosterone, nor with their 1,4-diene analogs under the same conditions.Acknowledgments. This work was supported by grants from the Consejo Nacional de Investigaciones Científicas y Técnicas de la República Argentina to the Instituto de Biologia y Medicina Experimental and the Programa de Regulación Hormonal y Metabólica as well as by financial help from the Secretaría de Ciencia y Tecnología.     

Structure,biosynthesis and functions of glycoprotein glycans

Since the pioneering work on structure and function of heteroglycans compiled in the classical books edited by A. Gottschalk in 1972¹, there have been several promising developments in glycoconjugate research, as reviewed in this article.In Part 1, contributed by A. Kobata, current knowledge on heteroglycan structures is presented and representative examples taken from higher organisms are given. Part 2, written by J. F. G. Vliegenthart and J. P. Kamerling, covers the most important achievements in methodology: procedures to obtain pure glycans and to analyze their structures. Part 3, contributed by J. Paulson, is devoted to biosynthesis of glycans now describable as pathways since several of the glycosyltransferases have been isolated and analyzed for specificity. In Part 4, contributed by E. Buddecke, current knowledge on functional roles of glycans is presented. It will become apparent that the prerequisite for valid work either in biosynthetic or functional context depends on solid structural information. This is particularly true whenever glycosyltransferase reaction products are being analyzed, or glycans involved in biological functions are investigated. Although in past years, a great deal of important knowledge has been gathered by use of crude glycosidase or glycosyltransferase activities (a notable example is found in reference 2), one may now postulate that glycans implicated in biological reactions should be thoroughly analyzed.This review may familiarize newcomers with the field of glycoconjugate research with special emphasis on glycoprotein glycans. Glycolipids are not included in this article as they have recently been reviewed by S. I. Hakomori³. The reader is also referred to several excellent monographs^4,5 and the Proceedings of the Glycoconjugate Symposia held biannually^6–8.     

Insulin stimulation of glucose and amino acid transport in mouse fibroblasts with elevated membrane microviscosity

Summary Basal and insulin-stimulated transport of 2-deoxy glucose and of -aminoisobutyric acid in mouse 3T3 fibroblasts were modulated by increasing the lipid microviscosity of the cell plasma membrane. The kinetics indicate that the insulin effect is induced either by recruitment of new transport carriers or by reduction of the translocation activation energy.This investigation was supported by grant No.5-R01-CA-27471-02, awarded by the National Cancer Institute, Department of Health, Education and Welfare.     

Leydig cell andΔ 5-3β-hydroxysteroid dehydrogenase activity in the testis of toad (Bufo melanostictus) following cold exposuredehydrogenase activity in the testis of toad (Bufo melanostictus) following cold exposure

Summary Leydig cell nuclear area and ⁵-3-hydroxysteroid dehydrogenase activity were increased in the testis ofBufo melanostictus 2 days after a single short-term cold exposure. Both parameters returned to normal values 4 days later.