Occurrence of anthocyanoplasts in cell suspension cultures of sweet potato

Intensely pigmented and spherical vesicles (anthocyanoplasts) were found in anthocyanin-containing cells of sweet potato (Ipomoea batatas) suspension cultures. Anthocyanin synthesis began to first occur 24–48 h after exposure to light, and then numerous small red vesicles were detected under a microscope. The frequency of anthocyanoplast-containing cells rapidly increased to finally about 80% of the total cultured cells after 5 days of irradiation. Fully developed anthocyanoplasts reached 10–15 m in diameter. On the other hand, neither anthocyanin synthesis nor development of anthocyanoplasts was induced in the dark-cultured cells. 2,4-D also inhibited anthocyanin synthesis and development of these vesicles. The results suggest that anthocyanoplasts might be a site of anthocyanin synthesis and/or accumulation.Abbreviation 2,4-D 2,4-dichlorophenoxyacetic acid     

Receptive field mechanisms of ganglion cells in the cat retina

On the basis of anatomical and physiological results of the vertebrate retina, a method is proposed for analysing the respective fields of ganglion cells in the cat retina. In the model, we assume the following: (a) Ganglion cells receive their input from bipolar and/or amacrine cells. (b) The nonlinearity of ganglion cell responses is due to the activities of transient type amacrine cells. The method has been proved to be effective. According to the results of this investigation, the receptive field properties of X type and Y type ganglion cells are heterogeneous. Thus, it may be considered that their receptive fields consist of center and surround mechanisms. The receptive field properties of X-cells are almost linear and the X-cells seem to receive most of their input from bipolar cells. On the other hand, the ones of Y-cells are highly nonlinear. Consequently, it is conceivable that the Y-cells receive their input mainly from transient type amacrine cells.     

Level of translatable messenger RNA coding for argininosuccinate synthetase in the liver of the patients with quantitative-type citrullinemia

Summary The translation activity of mRNA coding for argininosuccinate synthetase in total RNA extracted from the liver of three patients with quantitative-type citrullinemia was determined using a cell-free translation system. In two patients, the hepatic content of the enzyme was about 20% of the control value, whereas translatable mRNA level for the enzyme was similar to or slightly lower than those of control livers. In the third patient, the enzyme content was about 50% of the control value, and mRNA activity for the enzyme was low normal. These results indicate that at least in the first two patients, the decrease in the enzyme protein is due either to increased degradation of the enzyme or to decreased translation in the patient's liver.     

Possible sensory receptor of nonadrenergic inhibitory nervous system

To determine the sensory receptor of the nonadrenergic inhibitory nervous system (NAIS), 22 cats were anesthetized and serotonin was continuously administered (50-250 micrograms.kg-1.min-1 iv) to increase pulmonary resistance (RL) to 377 +/- 57% (SE) of the control value. We then 1) mechanically irritated the trachea, 2) intravenously administered capsaicin (5 micrograms/kg), or 3) induced hypoxia (arterial PO2 30-40 Torr) to stimulate irritant and bronchial C-fiber receptors, pulmonary C-fiber receptors, or the carotid body (chemoreceptors), respectively. After treatment with atropine (3 mg/kg iv) and propranolol (2 mg/kg iv), the serotonin-induced change in RL was reduced by 58.6 +/- 14.3% by mechanical irritation and 63.3 +/- 12.1% by intravenous capsaicin. However, hypoxia produced no dilatation of the airways. In further experiments, we employed capsaicin inhalation to stimulate bronchial C-fiber receptors. Inhaled capsaicin (0.1%, for 5 breaths) also reduced RL by 79.2 +/- 9.2% of the elevated value, after atropine and propranolol. Treatment with a ganglionic blocking agent, hexamethonium (2 mg/kg iv), abolished bronchodilator responses, implying that a reflex pathway through vagal nerves is involved in this phenomenon. These results suggest that pulmonary and bronchial C-fiber receptors may be involved as sensory receptors in NAIS reflex bronchodilatation.     

Effect of 5-azacytidine on the differentiation of human leukemia K-562 cells

The treatment of K-562 cells with 10(-5) M to 10(-7) M 5-azacytidine induced a marked increase in benzidine-positive cells. Similarly, the exposure of K-562 cells to 2 X 10(-3) M butyric acid or 5 X 10(-7) M 1-beta-arabinofuranosylcytosine or 1 X 10(-3) M hydroxyurea induced an erythroid differentiation of K-562 cells. The activity of DNA-methyltransferase and the level of methylcytosine in newly synthesized DNA were significantly decreased when the cells were treated with 5-azacytidine or butyric acid, while 1-beta-arabinofuranosylcytosine or hydroxyurea had no inhibitory effect on DNA-methylation of K-562 cells. These results suggest that the inhibition of DNA-methylation is not necessarily a specific phenomenon for erythroid differentiation of K-562 cells.     

Distribution and biosynthesis of aminopeptidase N and dipeptidyl aminopeptidase IV in rat small intestine

The regional, cellular and subcellular distribution patterns of aminopeptidase N and dipeptidyl aminopeptidase IV were examined in rat small intestine. Aminopeptidase N of brush border membrane had maximal activity in the upper and middle intestine, while dipeptidyl aminopeptidase IV had a more uniform distribution profile with relatively high activity in the ileum. Along the villus and crypt cell gradient, the activity of both enzymes was maximally expressed in the mid-villus cells. However there was substantial dipeptidyl aminopeptidase IV activity in the crypt cells. Both enzymes were primarily associated with brush border membranes in all segments, however, in the proximal intestine, a significant amount of dipeptidyl aminopeptidase IV activity was associated with the cytosol fraction. The cytosol and brush border membrane forms of dipeptidyl aminopeptidase IV were immunologically identical and had the same electrophoretic mobility on disc gels. In contrast, the soluble and brush border membrane-bound forms of aminopeptidase N were immunologically distinct. When the total amount of aminopeptidase N and dipeptidyl aminopeptidase IV was determined by competitive radioimmunoassay, there were no regional or cellular differences in specific activity (enzyme activity/mg of enzyme protein) of either enzyme in brush border membrane and homogenate. The specific activity of both enzymes in a purified Golgi membrane fraction as measured by radioimmunoassay was about half that of the brush border membrane fraction. These results suggest that (1) aminopeptidase N and dipeptidyl aminopeptidase IV have different regional, cellular and subcellular distribution patterns; (2) there are enzymatically inactive forms of both enzymes present in a constant proportion to active molecules and that (3) a two-fold activation of precursor enzyme forms occurs during transfer from the Golgi membranes to the brush border membranes.     

Experimental studies on vertical infection of mice with Japanese encephalitis virus. IV. Effect of virus strain on placental and fetal infection

An experiment was carried out to examine the effect of an inoculated strain of Japanese encephalitis virus on the establishment of experimental vertical infection of mice with this virus. In it, closed-colony mice of the CFW strain were inoculated intravenously with seven strains of the virus at 7 days of pregnancy. After that, an attempt was made to recover the virus from placenta and fetus, so that the infection rate of each strain might be determined. As a result, the infection rate was high for both placenta and fetus in the case of the AS-6 and Sagara strains both of which had undergone three passages in the mouse brain. The placental infection rate was high and the fetal infection rate relatively low in the case of the JaGAr01 and Fuji strains which had undergone 7 and 150 passages, respectively, in the mouse brain. The infection rate was very low for both placenta and fetus in the case of the Nakayama-Yakken strain which had undergone more than 100 passages in the mouse brain. There was no difference in the severity of viremia after inoculation between the AS-6 and Fuji strains. Both placental and fetal infection rates were low in the case of the JaTH160 strain which had undergone passages in mice by intraperitoneal inoculation and which presented a strong peripheral infectivity and induced a severe viremia after inoculation. Neither placental nor fetal infection occurred in the case of the S- strain used as live virus vaccine. These results indicated that placental and fetal infection rates varied from one virus strain to another.(ABSTRACT TRUNCATED AT 250 WORDS)     

Hydropiperoside,a novel coumaryl glycoside from the root of Polygonum hydropiper

From the methanol extract of the root of Polygonum hydropiper, a novel coumaryl glycoside hydropiperoside was isolated together with anthraquinone, ellagic acid 3,3′-di-O-methyl ether, gallic acid, two quercetin glycosides and an unidentified aromatic δ-lactone possessing antifertility activity. The structure of hydropiperoside was established as β-d-(1,3,6-tri-p-coumaryl)-fructofuranosyl-α-d-glucopyranoside by combination of extensive ¹H NMR and ¹³C NMR spectra, and the FD/MS spectrum.