The biological activity of interferon alpha is influenced by two distinct regions in the protein

With the aim to assign differences in activity between murine interferon-alpha 1 and -alpha 4 to specific amino acids, we have constructed hybrid genes and analysed the antiviral properties of the corresponding hybrid proteins. The hybrid genes were constructed by means of homologous recombination between the alpha 1 and alpha 4 genes in Escherichia coli. Hybrids in which the N-terminal part is derived from alpha 1 show that two regions have a major effect on the activity: amino acid 10-20 and 55-67. When comparing hybrids with N-terminal alpha 4 sequences, transitions in activity are found in the same regions. Interestingly, the curves for the two sets of hybrids are exactly each others mirror image.     

Transformation of erythrocytes and their ultrastructure with respect to aging

Transformation and ultrastructure of erythrocytes have been investigated in 58 white non-inbred rats on the 1st, 2nd, 3d days after birth and at the age of 1.5, 3, 8, 20 months. The transformation index of the erythrocytes drops by the 8th month of life and further it rises in old animals. In newborn rats echino-poikiloid forms predominate; they are mainly presented as reticulocytes with remnants of nuclei, mitochondria and other organells. During first three days of life cells of the erythroid line actively free themselves from the nucleus by means of its pyknosis and chromatinolysis. In newborn rats erythrocytes have folds of plasmolemma of linear and spotted form on their surface; their number sharply decreases in mature animals. The least changes in form and ultrastructure of erythrocytes are noticed in 3-8-month-old animals.     

Chromatin matrix activity in hepatocyte nuclei after disturbance of the hepatic vagal innervation

The level of matrix activity of extranucleolar and nucleolar chromatin in hepatocytes of white noninbred rats has been studied in dynamics after disturbance of the vagal innervation. In order to estimate the labelling intensity of nuclear structures, the histoautoradiographic method is used. After bilateral subdiaphragmal vagotomy at early stages (1-2 weeks) the level of the nucleoplasm and nucleolus increases essentially, and by the 30th day a tendency to its normalization is noted. A conclusion is made that the peripheral nervous system influences the intensity of metabolic processes in the nucleus.     

Vimentin-positive epithelial cells in aggregated lymphoid nodules (Peyer's patches) in rabbits

Peculiarities of cytoskeleton in membranous cells and disposition of the latter in the cupola epithelium in aggregated lymphoid nodules++ (ALN) have been studied in the ileum of 5 rabbits. The material has been fixed in liquid nitrogen and in the mixture of paraformaldehyde and glutar aldehyde. Methods of immunomorphology, high resolving light and transmissive electron microscopy have been used. Monoclonal antibodies to vimentin are selectively bind with a specific population of the ALN cupola epithelial cells. These cells are regularly arranged in the epithelium of the cupola lateral part and they are absent in the epithelium of the intestinal crypts, villi and apex of the cupolas. In the lateral epithelium of the cupolas surface, nearer to their base vimentin-positive++ epitheliocytes make contacts with single interepitheliocytic lymphocytes, and nearer to the apex they surround compact groups of the interepitheliocytic lymphocytes. The vimentin-positive++ epitheliocytic cells are identified as M-cells.     

Changes in the cellular composition of the deciduous membrane in physiologic pregnancy and late toxicosis

Cytochemical characteristics of the decidual membrane at a physiologically normal pregnancy and in cases of late toxicosis are presented. Three main cell types of the decidual membrane are defined: large decidual cells (LDC), small decidual cells (SDC) and granular cells of endometrium, or K-cells. Part of each cell type in the decidual membrane is determined. At physiologically normal pregnancy the part of the LDC makes 50-60% in the membranes and 80-85% in the basal plate of the placenta; SDC--10-18% in the fetal membranes and 1-2% in the basal plate of the placenta; K-cells--0.5-1%. At late toxicosis of pregnancy there is a change in relative and absolute amount of the decidual cells: the part of the LDC decreases up to 26-40% in the fetal membranes and up to 55% in the basal plate of the placenta; part of the K-cells at a slight form of preeclampsia rises up to 3-4%, at a severe form--up to 11-12%. The change in cell composition results in certain disturbances of physiological equilibrium of biologically active substances produced by the decidual cells. This correlates with the severity and clinical manifestations of the late toxicosis of pregnancy. Correlation of the decidual cells disfunction, directed to regulation of their reproduction and functioning, can become one of the elements of pathogenic treatment of the late toxicosis of pregnancy.     

Non-C-G recognition sequences of DNA cytosine-5-methyltransferase from rat liver

The eukaryotic DNA cytosine-5-methyltransferase (E.C.2.1.1.37) is known to methylate cytosine in DNA mainly, but not exclusively in C-G. In the present study the minor, non-C-G recognition sequences of a rat DNA methyltransferase were analyzed by Maxam-Gilbert sequencing of in vitro methylated SV40 DNA. The enzyme methylates C-A and C-T at a 50-fold lower initial rate than C-G. Methylation of C-C at the 5'C was not observed in the piece of DNA sequenced. The methylation of C-A is very low in the trinucleotides ACA and CAC, the other C-A containing trinucleotides in DNA are much better methylacceptors. C-T was found methylated predominantly in the sequences CCTAA, ACTAA, and ACTGT. A comparison of the activity with different substrates is in favour of the enzyme making its recognition in the major groove of the DNA.     

Localization of c-ERB A proteins in rat liver using monoclonal antibodies

Monoclonal antibodies were raised against the nuclear thyroid hormone receptors encoded by c-ERB A genes and against a purified nuclear receptor fraction. These antibodies recognize the c-ERB A protein in nuclear extracts from rat liver and are able to compete with thyroid hormone in Scatchard analyses. In sections of rat liver they react with all the hepatocyte nuclei as well as with the cells of the hepatic bile ducts. Comparison with another putative T3 receptor antibody, described previously, showed that distinct 57 kD proteins with a different cellular distribution were recognized.     

Hydrodynamic and circular dichroic analysis of mammary-derived growth inhibitor (MDGI)

The mammary-derived growth inhibitor exists in solution as a monomeric molecule with a molar mass of 14,500 +/- 400 g/mol. The largest diameter and the height of the polypeptide chain were estimated to be 3.75 +/- 0.25 nm and 2.01 +/- 0.13 nm respectively. This is in good agreement with the structurally related bovine peripheral myelin P2 protein (about 70% amino acid sequence homology). CD measurements have revealed MDGI to be a protein with about 50% beta structure and less than 20% alpha helix similarly as in fatty acid-binding proteins. Removal of endogenous long-chain fatty acid by lipidex or storage in the frozen state lead to a destabilization of the active MDGI conformation which is accompanied by a loss of its activity with regard to growth inhibition of Ehrlich Ascites cells.     

Primary structure of a pyrroloquinoline quinone (PQQ) containing peptide isolated from porcine kidney diamine oxidase

After treating porcine kidney diamine oxidase (PKDAO, EC 1.4.3.6) with the inhibitor 2,4-dinitrophenylhydrazine (DNPH), the enzyme was subjected to proteolysis with trypsin. The hydrolysate contained a peptide to which the C(5) hydrazone of PQQ and DNPH (PQQ-DNPH) was bound. The peptide was purified to homogeneity after which the amino acid sequence was determined. It appeared to consist of 11 amino acids, with PQQ bound to number eight. Further proteolysis of the peptide with aminopeptidase and carboxypeptidase gave a compound which was identical to a product prepared from coupling of PQQ-DNPH to lysine. Therefore, the cofactor in PKDAO has most probably an amide bond between one of its carboxylic acid groups with the epsilon-NH2 group of a lysine residue. Possibilities for attachment of the cofactor to the protein chain are discussed.     

The rho gene product expressed in E. coli is a substrate of botulinum ADP-ribosyltransferase C3

The ras-related rho A protein expressed in E. coli, was ADP-ribosylated by botulinum ADP-ribosyltransferase C3. C3 also modified the valine-14 mutant rho protein but not the products of H-ras, R-ras, ral, ypt, and rap 1 genes. A ras-rho chimaera consisting of 60 amino acids from the amino terminus of ras fused to 133 amino acids from the carboxy terminus of rho was not modified by C3. Antibodies raised against the porcine brain cytosolic substrate of C3 cross reacted with the rho, valine-14 rho and ras-rho proteins, but not with the gene products of H-ras, R-ras, ral or rap 1. Polyclonal anti-H-ras antibodies cross reacted with H-ras but not with ral, rho, or the C3 substrate purified from porcine brain.