Protein S binding in relation to the subunit composition of human C4b-binding protein

The human regulatory complement component C4b-binding protein (C4BP) circulates in plasma either as a free protein or in a bimolecular complex with the vitamin K-dependent protein S. The major form of C4BP is composed of 7 identical, disulfide-linked 70 kDa subunits (alpha-chains), the arrangement of which gives the C4BP molecule a spider-like appearance. Recently, we identified a unique 45 kDa subunit (beta-chain) in C4BP. We have now isolated a subpopulation of C4BP, which does not bind protein S. This C4BP species, which had a molecular weight slightly lower than that of the predominant form, was found to lack the beta-chain. Another lower molecular weight form of C4BP was also purified. It contained the beta-chain and was efficient in binding protein S. Its subunit composition was judged to comprise six alpha-chains and one beta-chain. These results indicate C4BP in plasma to be heterogeneous at a molecular level vis-a-vis subunit composition and/or protein S binding ability and provide support for the concept that the beta-chain of C4BP contains the single protein S binding site.     

A cDNA clone encoding the precursor for a 10.2 kDa photosystem I polypeptide of barley

Two cDNA clones for the barley photosystem I polypeptide which migrates with an apparent molecular mass of 9.5 kDa on SDS-polyacrylamide gels have been isolated using antibodies and an oligonucleotide probe. The determined N-terminal amino acid sequence for the mature polypeptide confirms the identification of the clones. The 644 base-pair sequence of one of the clones contains one large open reading frame coding for a 14 882 Da precursor polypeptide. The molecular mass of the mature polypeptide is 10 193 Da. The hydropathy plot of the polypeptide shows one membrane-spanning region with a predicted -helix secondary structure. The gene for the 9.5 kDa polypeptide has been designated PsaH.     

Spinal ascending projections to the nucleus tractus spinalis nervi trigemini of the dog

Seven dogs were subjected 30 min to ligation of the thoracic aorta and were then kept alive 6-7 days after the ligature had been removed. Their spinal cord and brain stem were treated by the Nauta-Gygax method and the extent and appearance of preterminal and terminal degeneration of certain ascending spinal systems were analysed. In the medulla oblongata region, marked degenerating fibres from the lower thoracic and lumbosacral cord segments were found in the nucleus tractus spinalis nervi trigemini. Preterminal and terminal degenerating fibres were visualized in the caudal part of the trigeminal nuclear complex. Comparison with the literature showed these to be previously unknown projections with a relationship to the nucleus tractus spinalis nervi trigemini.     

Production ofd-mannitol fromd-aldopentoses by the yeastRhodotorula minuta

Rhodotorula minuta produced 16% ofd-mannitol and 3% ofd-arabinitol when cultivated ond-ribose, 4% of mannitol and 11% of arabinitol when grown ond-xylose, 5% ofd-mannitol and 5% ofd-arabinitol when grown ond-arabinose, and 5% ofd-mannitol and 6% ofd-arabinitol when cultivated ond-lyxose.     

Production of milk-clotting enzymes by basidiomycetes

BasidiomycetesPhellinus chrysoloma, Kuehneromyces mutabilis andGanoderma applanatum produce extracellular milk-clotting enzymes. The enzymes are acid proteinases stable at 40°C and within pH 3–5.5. Only the enzyme preparation fromP. chrysoloma exhibits properties comparable with animal chymosin.     

Conversion of disaccharides to 3-ketodisaccharides by nongrowing and immobilized cells ofAgrobacterium tumefaciens

High-performance liquid chromatography was used to estimate 3-ketolactose and 3-ketosucrose in cultures of agrobacteria. The activities of enzymes that convert the disaccharide substrate were evaluated during batch cultivation ofAgrobacterium tumefaciens on sucrose, maltose, and lactose. The highest activity of glucoside 3-dehydrogenase and a slight activity of disaccharide-hydrolyzing enzymes were found in cells grown on lactose. Nongrowing cells converted lactose to 3-ketolactose faster than immobilized cells did. Immobilization of cells into polysaccharide gels did not stabilize the activity of glucoside 3-dehydrogenase. Glutaraldehyde cross-linking of the cell content led to an inactivation of the respiratory chain but Fe³⁺ could be used as an electron acceptor. Cells treated with glutaraldehyde converted lactose faster than nongrowing ones but the activity of glucoside 3-dehydrogenase was not stable.     

Formation and exocytosis of secretory granules in the endocrine cells of normal and transplanted pancreas: an electromicroscopic study

The mechanism of secretory granule formation and exocytosis in the endocrine cells of normal and transplanted rat pancreas was studied using electron microscopy. On the one hand, formation of secretory granules starts with the dilatation of the 2 ends or the vesicularization of the middle parts of rough endoplasmatic reticulum (RER). On the other hand, prohormone ribosomes condense into the vesicles of the GOLGI apparatus. This probably indicates that the GOLGI complex is not the only source of formation of secretory granules. Exocytosis occurs with the formation of an electron dense streak between the perigranular membrane and the apical cell membrane. This is followed by the rupture of the streak at this midpoint allowing the granule to extrude into the space between the cell membrane and the parenchymal basal membrane. This fusion-rupture-extrusion mechanism repeats itself at the parenchymal and capillary basal membranes and also at the endothelium until it gets into the capillary lumen, showing that hormones of pancreatic endocrine cells may be actively transported into circulation as intact secretory granules. There is no significant morphological difference between the mechanism of secretory granule formation in normal and transplanted pancreatic tissue.     

Phenotypic and genetic differentiation of human populations with respect to morphologic and psychophysiological traits

Four groups of human characters (mendelian markers, anthropometry, neurodynamics and psychodynamics) were studied in eight human populations characterized by different degrees of isolation and different ethnic backgrounds, and located in different ecological conditions. The populations examined were proved to display phenotypic and genetic differentiation for the studied groups of characters which were compared with linguistic and geographical distances. The role of genetic factors and that of environmental factors was shown to diminish and to increase, respectively, as the degree of complexity of expression of the group of characters under study (from anthropometry to psychodynamics) goes up.