Oscillations of cytoplasmic concentrations of Ca2+ and K+ in fused L cells

Summary Using Ca²⁺- and K⁺-selective microelectrodes, the cytosolic free Ca²⁺ and K⁺ concentrations were measured in mouse fibroblastic L cells. When the extracellular Ca²⁺ concentration exceeded several micromoles, spontaneous oscillations of the intracellular free Ca²⁺ concentration were observed in the submicromolar ranges. During the Ca²⁺ oscillations, the membrane potential was found to oscillate concomitantly. The peak of cyclic increases in the free Ca²⁺ level coincided in time with the peak of periodic hyperpolarizations. Both oscillations were abolished by reducing the extracellular Ca²⁺ concentration down to 10^–7 m or by applying a Ca²⁺ channel blocker, nifedipine (50 m). In the presence of 0.5mm quinine, an inhibitor of Ca²⁺-activated K⁺ channel, sizable Ca²⁺ oscillations still persisted, while the potential oscillations were markedly suppressed. Oscillations of the intracellular K⁺ concentration between about 145 and 140mm were often associated with the potential oscillations. The minimum phase of the K⁺ concentration was always 5 to 6 sec behind the peak hyperpolarization. Thus, it is concluded that the oscillation of membrane potential results from oscillatory increases in the intracellular Ca²⁺ level, which, in turn, periodically stimulate Ca²⁺-activated K⁺ channels.     

Biological activity of monomeric Sendai virus HN glycoprotein

Abstract We have developed a transformation system for Streptomyces wadayamensis , a cephamycin C producer. 1−5 × 10⁹ protoplasts can be obtained when late logarithmic phase cultures of this microorganisms are incubated with 10 mg/ml of lysozyme. Polyethylene glycol-Ca²⁺-mediated transformation of these protoplasts yielded 10⁶ transformants per μg of pIJ702 or pIJ365 DNA.     

Possible Role of Hexosamine-Containing Cell Wall Component in Growth Regulation of Rice Coleoptiles

The cell wall of rice coleoptile was found to contain severalhundred microgram hexosamine per gram dry wt with the pectic,hemicellulosic, and -cellulose fractions containing 50%, 40%,and 10%, respectively. The cell wall hexosamine content increasedseveralfold with coleoptile growth and was higher in air-typecoleoptiles (grown on the surface of water) than water-typeones (grown under water). Rice coleoptiles were cultured in glucosamine, NH₄⁺, glutamine,or asparagine solution and growth was inhibited at 10^–4M and above. Coleoptile growth capacity in glucosamine or NH₄⁺solution correlated inversely with the cell wall hexosaminecontent. Both of these solutions also inhibited elongation ofsubmerged air-type coleoptile sections. Azaserine promoted thegrowth of both intact and excised coleoptiles at 10^–6to 10^–5 M and halved the cell wall hexosamine contentof intact ones. 6-Diazo-5-oxo-L-norleucine promoted the elongationof sections. These results suggest that the hexosamine-containingcell wall component is an important growth suppression factorin rice coleoptiles. (Received April 25, 1983; Accepted August 30, 1983)     

Amino Acid-Sugar Linkages in Rice Coleoptile Cell Walls

The nature of amino acid-sugar linkages in cell walls was investigatedin a monocotyledonous tissue, rice coleoptiles. The molar ratiosof aspartic acid, threonine, and serine in cell walls were decreasedby hydrazinolysis in coleoptiles grown both on and under water.The molar ratios of threonine and serine were decreased alsoby a NaOHNaBH₄ treatment, while the alanine content was increased,and -aminobutyric acid was not formed. The cell walls were treated with NaOH in the presence of NaB³H₄,hydrolyzed, then divided into amino acid and sugar fractions.Two distinct radioactive peaks were detected in the thin-layerchromatography of the amino acid fractions. One was identifiedas alanine derived from glycosylated serine; the other was confirmedto be an oxidation product of glucosaminitol. There was justone ³H-labeled product in the sugar fractions, galactitol. Theseresults suggest the presence of serine-O-galactose and asparagine-N-N-acetylglucosamine linkages in rice coleoptile cell walls. The existence of glucosamine linked to amino acids was furthersupported by the incorporation of ¹⁴C-glucosamine into cellwalls. These linkages were also detected in the cell walls ofa dicotyledonous tissue, Vicia epicotyls. (Received April 2, 1981; Accepted June 24, 1981)     

The role of sialic acid in the nerve terminal for the release of transmitter

The role of sialic acid in the frequency of miniature endplate potentials (MEPPs) was examined using neuraminidase and gangliosides in the mouse diaphragm. Neuraminidase increased and decreased MEPP frequency in normal K⁺ and high K⁺ solution, respectively. The effects were dependent on the presence of Ca²⁺ in extracellular medium. Neuraminidase liberated sialic acid from and lowered Ca²⁺- binding capacity of synaptosomal membrane. Gangliosides treatment of the tissue partially restored the effects of neuraminidase on the frequency of MEPP and Ca²⁺-binding capacity. It is possible that sialic acid in the nerve endings provides a functional storage site which supply intracellular Ca²⁺ to cause a transmitter release.     

Plant regeneration from grape callus stored under a combination of low temperature and silicone treatment

Effects of the combination of low temperature and silicone treatment on the storage of grape callus (Vitis vinifera L. x V. labrusca L. cv. Kyoho; V. vinifera L. cv. Koshusanjaku) were examined. In Kyoho, the calli were stored at 10°C successfully for up to 360 days. Embryogenic calli of Koshusanjaku stored at 10°C retained the ability of embryogenesis after 360 days of storage. However, the color of both calli became brownish. This was improved by the combination of low temperature and silicone treatment. The calli of Kyoho survived by the storage under the combination of 15°C and silicone. Embryogenic calli stored at 10 and 15°C in combination with silicone survived for 360 days, and regenerated only after transfer onto a regeneration medium. Thus the combination of low temperature and silicone affects the longevity of the grape callus.     

Overproduction of human insulin-like growth factor-II inEscherichia coli

Summary Human insulin-like growth factor II (hIGF-II) was produced inEscherichia coli as a protein fused to human growth hormone. High level expression of the fusion protein was attained with pIBL-1 plasmid. The hIGF-II obtained byin vitro cleavage of the fusion protein with cyanogen bromide was highly purified and its biological activity was assessed.     

Aerobic and anaerobic metabolism in a facultative anaerobe Ep01 lacking cytochrome, quinone and catalase

Abstract A facultative anaerobe, strain Ep01 produced a mixture of pyruvate, formate, acetate and ethanol from glucose anaerobically, and acetate and pyruvate aerobically. Cell extract of anaerobic-grown cells contained active pyruvate formatelyase, aldehyde dehydrogenase and alcohol dehydrogenase, while cell extract of aerobic grown cells contained an active pyruvate dehydrogenase system, NaDH oxidase and NADH peroxidase. Levels of acetate kinase and phosphate acetyltransferase activities were not significantly different in cells grown under either condition. Based on the metabolic products and the emzyme activities, we propose the presence of two metabolic pathways in strain Ep01, namely, a pathway to form formate, acetate and ethanol under anaerobic conditions, and a pathway to form under aerobic conditions. This explains why strain Ep01 can grow well both under strictly anaerobic conditions and well-aerated conditions.     

Neochilenin,a new glycoside of 3-O-methylquercetin,and other flavonols in the tepals ofNeochilenia,Neoporteria andParodia species (Cactaceae)

3-O-Methylated flavonols were isolated as crystals for the first time from the flowers ofNeochilenia, Neoporteria andParodia species belonging to the sub-family Cereoideae (Cactaceae), which are native to South America. The structures of three compounds were confirmed by chemical and spectral means. In the tepals of 7 species ofNeoporteria, 3-methyl ether of quercetin was found in the form of aglycone, whereas it was present as the 7-O-glucoside in the tepals ofParodia sanguiniflora and as the 4′-O-glucoside in the tepals of three species ofNeochilenia. Among those two glucosides of quercetin 3-methyl ether, the former has been found in a whole plant ofArtemisia transiliensis (Compositae), while the latter is new to the literature. Therefore, the term “neochilenin” may be assigned to this new pigment. Contribution from the Research Institute of Evolutionary Biology, No. 44.     

Effect of position in the uterus on the fetal weight of the 21st day of pregnancy in the unilaterally ovariectomized rat

Effects of intrauterine position of the fetuses on the weight of fetal sac, fetus and placenta were investigated on the 21th day of unilaterally (right) ovariectomized pregnant Wistar strain rats. Results were obtained as follows. 1. Litter size was negatively correlated with the mean weights of fetal sac and fetus. 2. The mean weights of male fetal sac and fetus were heavier than those of female ones, while there was no difference in the weight of placenta between male and female. 3. The mean weights of male fetal sac and fetus positioning ovarian end (OV) were lighter than those of ones at the other positions. And the highest frequency of the lightest weight of live fetuses was demonstrated at OV position. 4. The mean weights of male fetal sac and fetus positioning between two males (2M) were heavier than those of ones positioning not next to male (0M). And the mean weight of 2M female fetal sac was heavier than those of 0M one. 5. The mean weights of fetal sac and fetus positioning next to resorbed fetus were heavier than those of ones positioning not next to resorbed fetus.