Protein kinase(s) in bovine brain coated vesicles

Purified bovine brain coated vesicles contain protein kinase activity which phosphorylates 165, 54 and 50 kDa protein substrates. These phosphorylations do not seem to be induced by a unique protein kinase: indeed, the three substrates present different localizations in coated vesicles, the phosphorylation sites are either serine or threonine residues and vanadate and ATP[gamma S] have different effects on 32P incorporation in the substrates. Comparison of the coated vesicle protein and phosphorylation patterns from different tissues and animal origins shows that only the 50 kDa protein phosphorylation is always observed, compared to the great diversity in other minor phosphorylations which are observed or not in the various coated vesicles. The possible presence of a 50 kDa phosphoprotein phosphatase is also discussed. It is suggested that the 50 kDa protein with its connected specific kinase and phosphatase seems to constitute a regulatory system present in coated vesicles.     

Influence of the conformational state on the isoelectric points of rat brain synaptosomes, mitochondria and mitoplasts

The isoelectric points of rat brain synaptosomes, mitochondria and mitoplasts have been determined by using different charged two-phase systems containing dextran and poly(ethylene glycol). The cross-partition diagrams of these organelles show isoelectric points at pH 4.1, 4.5 and 4.7, respectively. The influence of the conformational state of mitochondrial membranes upon their partition in two-phase systems has been studied. Shrunk mitoplasts showed a large change in their partition behavior as reflected by an increased affinity for the lower dextran phase, while shrinkage of mitochondria did not affect their partition. Shrunk mitoplasts showed the same isoelectric point of pH 4.7 as swollen mitoplasts, which indicates that no charge changes occurred on the outer side of the inner mitochondrial membrane during shrinkage of mitoplasts.     

Immunochemical analysis of the membrane proteins of rat liver and Zajdela hepatoma mitochondria

The contents of mitochondrial inner membrane protein complexes were compared in normal liver and in Zajdela hepatoma mitochondria by the immunotransfer technique. Antibodies against core proteins 1 and 2, cytochrome c1, the iron-sulfur protein of Complex III, subunits I and II of cytochrome oxidase, and the alpha and beta subunits of the F1-ATPase were used. In addition, antibodies against a primary dehydrogenase, beta-hydroxybutyrate dehydrogenase, as well as the outer membrane pore protein were used. The results indicate that the components of the cytochrome chain and porin are greatly enriched in hepatoma mitochondria compared to normal rat liver mitochondria. This enrichment was also reflected in the rates of respiration in tumor mitochondria using a variety of substrates. Enrichment of porin may partially account for increased hexokinase binding to tumor mitochondria. In contrast to the respiratory chain components, the F1-ATPase and F0 (measured by DCCD binding) were not increased in tumor mitochondria. Thus, Zajdela hepatoma mitochondria components are nonstoichiometric, being enriched in oxidative capacity but relatively deficient in ATP synthesizing capacity. Finally, beta-hydroxybutyrate dehydrogenase, which is often decreased in hepatoma mitochondria, was shown here by immunological methods to be decreased by only 40%, whereas enzyme activity was less than 5% of that in normal rat liver.     

Action of veratridine on acetylcholinesterase in cultures of rat muscle cells

Studies on cultures of embryonic rat muscle cells have suggested that the presence of collagen-tailed forms may be correlated with spontaneous contractile activity: these forms disappear in the presence of tetrodotoxin which blocks the sodium channels involved in the propagation of action potentials. The effect of veratridine, a drug which maintains the sodium channels in the open state, was studied. It is shown here that in young cultures veratridine provoked a dramatic increase in total acetylcholinesterase activity and changed the distribution of the molecular forms of the enzyme, increasing the proportion and absolute amount of the A12 form. In order to elucidate the mechanism of action of this drug, the effects of various ions, ionophores, or other agents that modify the ionic permeabilities of membranes were also investigated.     

Effect of arginine modification on kidney brush-border-membrane transport activity.

The effect of phenylglyoxylation on brush-border-membrane functions was studied with membrane vesicles from rat kidney cortex. Na+-gradient-dependent uptake of phosphate, glucose and alanine was inhibited by 65, 88 and 70% by pre-incubation of vesicles with 50 mM-phenylglyoxal for 2 min. The inhibition showed a dependency for alkaline pH. Borate co-operativity in butanedione inactivation was used to prove that inhibition was caused by arginine modification. Intravesicular volumes, alkaline phosphatase, aminopeptidase M and Na+-H+ exchange were not affected by phenylglyoxal treatment. Inhibition of phosphate uptake was studied in more detail and showed that the chemical modification introduced by phenylglyoxal inhibited the overshoot of phosphate uptake caused by the Na+ gradient, and decreased the apparent maximal velocity of the phosphate-transport system in its interaction with Na+. Phosphate uptake measured in the absence of Na+ was not affected by phenylglyoxal. Shunting of the transmembrane electrical potential with K+ and valinomycin had no effect on phenylglyoxal inhibition, proving that the alteration of transmembrane electrical potential could not be responsible for this effect. Phenylglyoxal had no ionophoric effect on the Na+ gradients studied (1-100 mM). Na+ efflux was also unaffected by phenylglyoxal treatment. Na+, harmaline and amiloride were ineffective in protecting against phenylglyoxal inhibition, suggesting that the site modified was not an Na+-binding site. These results indicate the involvement of highly reactive arginine residues in phosphate, glucose and alanine uptake.     

Studies on chiasma frequency and distribution in two fertile men carrying reciprocal translocations; one with a t(9;10) karyotype and one with a t(Y;10) karyotype

Summary The frequency and distribution of chiasmata was investigated in two fertile carriers of reciprocal translocations, one with a 46,XY,t(9;10)(p22;q24) karyotype and one with a 46,X,-Y,+der(Y),t(Y;10)(q12;q24) karyotype. In both cases the chromosomes involved in the translocation showed an increase in chiasma frequency in comparison to karyotypically normal controls and in both cases this increase was localised, affecting only one interstitial segment of each translocation quadrivalent. In the t(9;10) case chiasmata appeared in substantial numbers in a novel location, the proximal two thirds of 9p, while in the t(Y;10) case chiasmata appeared in a conventional location, the medial region of 10q, but at an increased frequency. Furthermore there was evidence for inter-chromosomal effects in the t(9;10) case.     

Classification of non-Hodgkin's lymphomas: facts and perspectives]

Previous classifications of malignant non-Hodgkin lymphomas (nHL) are based on morphological and histological-cytological findings. The rapid development of immunology, the application of immunocytological, cytochemical and electromicroscopic methods led to new classifications of nHL based on immunology. They are founded on the idea that the prevailing cells of nHL correspond to a cell type from the differentiation line of lymphocytes. Thus, a distinction can be made between malignant lymphomas (ml) of stem, B and T-cells; the more frequently occurring lymphomas originating from B-cells are represented by chronic lymphatic leukaemia originating from B1-cells, by ml of follicular genesis (centrocytes, centroblastic-centrocytic ml, centroblasts) and by ml synthesizing and releasing immunoglobulins (immunocytoma, immunoblastoma). The type formerly called "reticulosarcoma" (histocytic ml) could be identified to be an immature, Ig synthesizing ml (immunoblastloma) in most cases. The new classification enables a more extensive differentiation and a better prognostic statement to be made than previous ones. The new units of disease can be diagnosed in most cases with light microscopic routine methods, although borderline cases and unclassifiable ml may occur.     

Etude hydrobiologique des lagunes du nord de la Tunisie

The limnology of three lakes in Tunisia was studied over a period of two years. These lakes differed substantially in the degree of salinity and resistivity. Physical and chemical parameters occurring in the lakes were analysed for a year. The investigation indicated some discussion about the following factors: Temperature, chlorides, potassium, sodium, calcium, carbonates, bicarbonates, dissolved oxygen, nitrats...In an another paper (second part), the author will study the interrelationships between annual variations of algal populations (plankton) and annual variations of these physical and chemical factors.