Transmembrane control of laminin, lectin receptors and surface villi in teratocarcinoma-derived endodermal cells

Distribution of laminin on the surface of teratocarcinoma-derived parietal endoderm cells was studied by immuno-histochemical staining of the fixed specimen using affinity-purified anti-laminin antibody. Laminin was distributed on the basal surface of the cells, while treatment either with colchicine or with cytochalasin D (CD) resulted in a severely polarized distribution; laminin was seen only at one end of the cell. Treatment with both the reagents did not cause the severe polarization. Receptors for lectins and cell surface villi were polarized by treatment with CD but not by treatment with colchicine. These results suggest that laminin--or its cell surface receptor--is linked to both microfilament and microtubules and that the mode of transmembrane control for laminin is different from certain other cell surface components of the cells.     

Cell-Free Synthesis of a Putative Precursor of Polygalacturonase in Tomato Fruits

By using a monospecific anti-polygalacturonase-2 antibody, a54K-dalton polypeptide was detected in in vitro translationproducts by a wheat germ cell-free translation system programmedwith polyadenylated RNA from ripe tomato pericarp tissue. Thisputative precursor of polygalacturonase was about 9K daltonslarger in molecular weight than polygalacturonase-2. (Received December 12, 1983; Accepted May 17, 1984)     

Different metastatic modes of malignant melanoma implanted in the ear of young and old mice

Summary An attempt has been made to determine (a) whether aging plays an important role in resistance against metastasis and (b) whether dithiothreitol, an effective in vitro mitogenic potentiator of splenic cells of young and old mice, can modulate the occurrence of pulmonary metastasis. B16-F10 melanoma cells were injected into the outer ear of young and old female C57BL/6 mice; and the growth of the primary tumor, the palpable size of the cervical lymph node, and the number of lung metastases were then determined at various intervals. The ear was amputated when the primary tumor reached 4 mm in mean diameter. The following results were obtained. (a) The growth rate of the primary tumor in young mice is comparable to that in old mice. (b) Enlargement of the cervical lymph node occurs earlier in old than in young mice. (c) Old mice are more vulnerable to pulmonary metastases, but small metastasized pulmonary colonies are more prominent in old than in young mice. (d) Dithiothreitol (100 g) injected every 2 days after the inoculation of tumor cells is effective in reducing the incidence of pulmonary metastases in old mice.     

Structure-spectrum correlations in nucleic acids. I. Raman lines in the 600-700 cm-1 range of guanosine residue.

Raman spectra of nine crystals of known structures which involve guanosine moieties with various conformations have been observed. It has been established that a guanosine residue with the C3'endo-anti conformation gives a strong Raman line at 666 +/- 2 cm-1. It has also been found that the residue with 04'endo-anti gives a strong Raman line at 682 cm-1, and C3'exo-syn at 616 cm-1. The usefulness of these structure-spectrum correlations in the conformation studies of polynucleotides are shown.     

The states of tyrosyl and tryptophyl residues in a protein proteinase inhibitor (Streptomyces subtilisin inhibitor

The states of tyrosyl and tryptophyl residues of a dimeric protein proteinase inhibitor, Streptomyces subtilisin inhibitor (Sato, S & Murao, S. (1973), Agric. Biol. Chem. 37, 1067) were studies by solvent perturbation difference spectroscopy with methanol, ethylene glycol, polyethylene glycol, and deuterium oxide as perturbants, and by spectrophotometric titration at alkaline pH. It appeared that all three tyrosyl residues per monomer of the inhibitor were exposed on the surface of the molecule, and their apparent pK values were estimated separately to be 9.58, 11.10, and 12.42. The single tryptophyl residue per monomer of the inhibitor appeared to be partially buried in the protein molecule.     

Is serotonin a chemical transmitter in the frog taste organ?

By artificially perfusing the frog tongue with serotonin (5HT) and its antagonists, the possibility of 5HT as a chemical transmitter from taste cells to nerve terminals in frog taste organ was examined. Although serotonin creatinine sulfate, when perfused through the lingual artery, produced impulse discharges in the glossopharyngeal nerve, creatinine sulfate elicited a similar response. Neural responses to taste stimuli were depressed by perfusion with 5HT. Among many antiserotonergic drugs perfused through the lingual artery, LSD was the only one which modified responses to taste stimuli. LSD suppressed taste responses to NaCl, CaCl₂ and water, while LSD at a high concentration (10^?5 g/ml) enhanced responses to guinine and HCl. When PCPA (DL-p-chlorophenylalanine) was injected intraperitoneally in conbination with reserpine, the agent did not significantly change taste responses. The above results possibly suggest that 5HT would not be a chemical mediator from taste cells to nerve terminals.     

Characterizations and constructions of reverberating networks

Consider the family $\text{G}$_n of all n neuron networks whose dynamical behaviors are described by Caianiello's neuronic equations, and also its subfamily $\text{R}$_n of all reverberating networks each of whose neuronic equations have only periodic solution (states), i.e., without having any transient states. This paper is specifically concerned with characterizations of the subfamily $\text{R}$_n. First, we show that $\text{R}$_n is contained in a subfamily $\text{S}$_n of $\text{G}$_n consisting of all self-dual networks. We introduce Chow's matrix corresponding to each network of $\text{S}$_n, using Chow parameters and some algebraic operations {$\text{2}$_α} applied to the coefficient matrix of the network in $\text{S}$_n, such as interchanges of coefficients between two neurons or changes of their signs. Then we give some necessary conditions on Chow's matrix under which any network in $\text{S}$_n belong to $\text{R}$_n, and a necessary and sufficient condition on the coefficient matrix. We also discuss relations between Chow's matrix and the maximum period of reverberations. In particular, it is shown that Chow's matrix of a network in $\text{R}$_n is symmetric if and only if the maximum period of reverberations is less than three. By virtue of these results, we propose two methods of construction of networks in $\text{R}$_n. The first method is an inductive construction. The second is based on the algebraic operations.     

Effects of exogenous soluble dextrans on insoluble glucan synthesis by Streptococcus mutans glucosyltransferase

Production of water-insoluble glucan (ISG) from sucrose by cell-free Streptococcus mutans AHT glucosyltransferase (GTF) first rapidly increased, and then sharply declined, as the amounts of water-soluble Dextrans T20 approximately T500 present, were increased. The decline of ISG synthesis was accompanied by an increased synthesis of the water-soluble fraction (SG). Prolonged incubation, however, induced enhanced synthesis of ISG even at higher dextran concentrations. The concentration of dextran required to stimulate or suppress ISG synthesis depended on the amounts of GTF used, but the extent of the stimulation was almost identical for the same GTF/dextran ratio. Thus, ISG synthesis is stimulated by the presence of dextrans at relatively low concentrations, but retarded at higher concentrations by being shifted to SG synthesis. ISG produced in the presence of dextrans contained higher proportions of alpha-1,6 glucosidic linkage and lower molecular size fractions, and possessed lower viscosity. These ISG products did not exhibit the coalescence of two component fibrils as observed with control ISG. These changes combined may contribute to the reduction of ISG-dependent adherence to glass of S. mutans cells by the presence of soluble dextrans, irrespective of their molecular size and concentration.