Studies on the restoration of the activities of Ribonucleases by polyamines in the presence of various ribonuclease inhibitors.

The effect of polyamines on ribonucleases in the presence of various inhibitors (poly(G), heparin, and rat liver RNase inhibitor) has been studied. Bovine pancreatic RNas A and a ribonuclease from horse submaxillary gland (RNase HS) were inhibited by the inhibitors, but RNase T1 and RNase M were not inhibited. Polyamines were found to restore the activites of RNase A and RNase HS inhibited by poly(G) or heparin but not those activities inhibited by rat liver RNase inhibitor. When poly(U) and poly(C) were used as substrates, the inhibitory effects of poly(G) and heparin were greater with poly(U) than poly(C) as a substrate. However, when poly(C) was used as a substrate in the presence of either of the above inhibitors, the restoration of RNase activity by sperimine was more efficient. In fact, a stimulatory effect was observed. From the double-reciprocal plots, it was concluded that polyamines restored the activiities of RNases by increasing the availability of the substrate and enzyme to each other. The restoration of enzyme activity by polyamines occurred through the binding of the polyamines to the inhibitor and the subsequent release of enzyme from the inhibitor.     

Detection and mapping of six miniF-encoded proteins by cloning analysis of dissected miniF segments

Summary Various DNA subfragments were derived from miniF DNA by complete or partial PstI cleavage, and cloned in the plasmid vectors pBR322 or dv1. The recombinant plasmids obtained were introduced into an Escherichia coli minicell-producing strain, and the plasmid-coded proteins were radiolabeled and analyzed by gel electrophoresis. Six miniF-encoded proteins, larger than 11 000 daltons, were detected and their coding regions were mapped on the F plasmid genome. Three of them were assigned by taking into account the known nucleotide sequences (Murotsu et al. 1981; K. Yoshioka, personal communication). The coding directions of some proteins were determined by inserting the lac promotor into one of the recombinant plasmids and analyzing the increase in production of the proteins. The coding direction of the five proteins analyzed so far was uniform. Comparison of these results with a functional map of miniF suggested possible roles of the proteins.     

Action spectra for the light inhibition of flowering and its reversal inLemna paucicostata T-101

Lemna paucicostata Hegelm. T-101, a short-day plant, flowers when plants preirradiated with red light (R) for 24 h are subjected to inductive darkness for 72 h followed by two short-day cycles (6 h R+ 18 h dark). However, flowering is inhibited by blue-or far-red-light pulses applied at the beginning of the inductive dark period. These inhibitory light effects are fully reversible by a R pulse. The action spectra for the inhibitory light effect and for its reversal show that the light pulses act exclusively through phytochrome. It is concluded that a low level of Pfr at the beginning of the inductive dark period prevents flowering.Abbreviations R red (light) - B blue (light) - FR far-red (light)     

Human pituitary corticotrophs: their amphophilic stainability and immunohistochemical characterization

Immunohistochemical characterization of the human pituitary beta(R) cells was investigated through the findings of the immunoreactivities with anti-porcine ACTH, -rat TSH, -rat FSH sera. Immunostained corticotrophs are oval or round in shape and localized in the anteromedial wedge. It is shown on the adjacent sections that they correspond to the beta(R) cells with amphophilic stainability with PAS-iron hematoxylin. In this wedge, amphophilic cells are preponderant, but PAS-positive thyrotrophs and gonadotrophs are not numerous. Amphophilic stainability varies in degree from cell to cell: One cell contains numerous medium-size of secretory granules weakly stained with iron hematoxylin and strongly with PAS in the PAS-positive cytoplasm, and the other cell is filled with big secretory granules intensively stained with iron hematoxylin and weakly with PAS. The immunostained TSH, LH and FSH cells are different from the beta(R) corticotrophs, because anti-ACTH serum never reacts to the TSH, LH and FSH cells in the two adjacent sections. LH and FSH reactivities are observed in the single cells. It is concluded that human corticotrophs are amphophilic beta(R) cells filled with secretory granules, and that they have quite a different appearance from the rat chromophobic stellate corticotrophs with a row arrangement of secretory granules along the plasma membrane.     

Effects of 2 water-soluble contrast media, meglumine iothalamate (Conray) and meglumine iocarmate (Dimer-X), on the electric activity of identifiable giant neurons of the African giant snail (Achatina fulica Ferussac)]

The influences of two water soluble contrast media, meglumine iothalamate and meglumine iocarmate, on the neuronal excitability and on the neuronal sensitivity to putative transmitters were examined in comparison with those of sucrose using two identifiable giant neurones of Achatina fulica Férussac (the TAN and the PON). A relatively low increase of osmotic pressure of the extracellular fluid, produced by the application of contrast media, reversed the Cl- dependent inhibition caused by a putative transmitter. The same increase of this osmotic pressure, however, did not influence the Cl- independent inhibition and the excitation of the neurone examined. The hyperpolarization of neuromembrane was caused by an increase of osmotic pressure of the extracellular fluid. Its relatively high increase was necessary to make spontaneous spike discharges disappear totally. All effects of the two contrast media, observed in this study, were due to the increase of osmotic pressure of the extracellular fluid ; no specific effect of the contrast media containing the iodine on the indicators used was observed.     

Purification and properties of a lambda operator-binding protein which is expected to be autorepressor (tof protein) from E. coli carrying lambdadv plasmid.

Summary In order to study the mode of action of the tof gene product, which is an autorepressor of the bacteriophage and plasmid dv, we have purified a DNA-binding protein which is specifically produced in bacteria carrying dv. This protein possesses characteristics expected for the product of the tof gene, since it is produced under conditions where cI-repressor is not made, and since it binds to oL and oR operators on the phage genome. The molecular weight of the native protein is 16,000–17,000 daltons, and the monomeric molecular weight as measured by gel electrophoresis in the presence of sodium dodecyl sulfate is about 10,000 daltons. Denaturation and renaturation experiments demonstrated that the native protein is a dimer of 10,000-dalton monomers. The DNA-specific binding protein is not produced in cells carrying i ²¹dv or 80dv.     

Bovine virus diarrhea-mucosal disease. II. Isolation and characterization of a cytopathogenic virus and experimental production of the disease.

A disease broke out in calves in the Tokachi district of Hokkaido. It induced pyrexia, respiratory symptoms, diarrhea, bloody feces, leukopenia, and sometimes erosion of the oral mucous membrane and muzzle. Its morbidity rate was 90% and its fatality rate 50%. Bovine virus diarrhea (BVD) virus was isolated from organs of dead calves and blood and feces of affected calves. It exhibited a cytopathic effect on calf kidney cell culture. Antisera against the Nose and the Oregon C24V strains of BVD virus showed an antibody titer of the same order against the homologous virus and the isolated strain. Antiserum against the isolated strain, however, showed much lower antibody titers against the Nose and the Oregon C24V strains than against the homologous virus. When inoculated with the isolated virus, two calves manifested acute symptoms, but recovered at any rate. One of them, however, suffered again from clinical infection and died eventually 37 days after inoculation. It presented pathological changes closely resembling those of the case of spontaneous infection. Virus was recovered from its principal organs, intestinal canal, and lymph nodes of various regions of the body.     

Random replication and random assortment model for plasmid incompatibility in bacteria

To understand the incompatibility between two related plasmids, both of which replicate in an autonomous state under a common control mechanism, we have developed a model that assumes a random choice mechanism for replication of plasmid copies and their random assortment into daughter cells upon cell division. Segregation kinetics by this model is analyzed mathematically and the number of generations required for segregation is calculated as a function of plasmid copy number per cell. The results obtained offer enough quantitative data to make our model reasonably realistic.     

Effect of dextran sulfate on the interaction between very low density lipoprotein and lipoprotein lipase

The effect of dextran sulfate on the interaction between very low density lipoprotein (VLDL) and purified bovine milk lipoprotein was studied. Dextran sulfate increased VLDL-triacylglycerol hydrolysis by lipoprotein lipase about 2-fold, but did not alter the Km value for triacylglycerol in VLDL. Strong association of dextran sulfate with the VLDL-lipoprotein lipase complex was demonstrated by gel filtration on BioGel A-5m, although dextran sulfate did not bind to VLDL and only very slightly to lipoprotein lipase. These findings suggest that dextran sulfate increases triacylglycerol hydrolysis in VLDL by binding to the VLDL-lipoprotein lipase complex.