Demonstration of light-induced potential change in Chara cells lacking tonoplast

Chara cells without tonoplasts, prepared by replacing the cellsap with EGTA-containing media, showed essentially the samepattern of light-induced changes in membrane potential and membraneresistance as normal cells although the concentrations of ionsand ATP in the cytoplasm decreased considerably (1/3–1/10)after loss of the tonoplast. Removal of the tonoplast reducedthe rate of photosynthetic O₂ evolution to about 50% of thatof normal cells but did not affect the magnitude of light-inducedpotential change. Not a full but a certain level of electronflow seems necessary to activate the putative electrogenic H⁺-pump. ¹ Present address: Department of Botany, Faculty of Science,University of Tokyo, Japan. ² Present address: Niigata College of Pharmacy, Niigata 950-21,Japan. (Received September 4, 1978; )     

Distribution of growth regulators in relation to the light-induced geotropic responsiveness in Zea roots

Growth regulators were measured in extracts from the upper and lower halves of 7-mm apical segments of horizontally oriented, red-light-irradiated and non-irradiated roots of Zea mays L. cv. Golden Cross Bantam 70 which exhibit a georesponse only after an exposure to light. Abscisic acid (ABA) was measured by gas-liquid chromatography, auxin (indole-3-acetic acid, IAA) by the Avena straight-growth assay, and an unidentified growth inhibitor by a Zea root-growth assay. The ratio of ABA in the upper and lower halves was 1.6 in the irradiated roots and 1.0 in the non-irradiated ones. The total amount of ABA after irradiation was increased by a factor of ca. 1.8. The ratio of IAA in the upper and lower halves of irradiated and non-irradiated roots was 1:3.4 and 1:2.9, respectively. The content (or activity) of an unidentified growth inhibitor was highest in the lower halves of horizontally oriented roots which had been irradiated with red light. The unidentified growth inhibitor, rather than IAA or ABA, may be the major factor in the light-induced geotropic responsiveness in Zea roots.     

Possible participation of glucocorticoid in elevation of 3',5'-cyclic AMP levels through inhibition of cyclic AMP phosphodiesterase.

Administration of prednisolone and cholate to rats elevated levels of cAMP (adenosine 3',5'-cyclic monophosphate) by 1.5- to 2.0-fold. Compounds such as prednisolone, hydrocortisone, cholate, and deoxycholate were found to be potent inhibitors of partially purified cAMP phosphodiesterase prepared from rat liver. Kinetic analysis showed that the prednisolone inhibition was noncompetitive with a Ki of 8.9 x 10(-4) M. These results suggest that in addition to increasing DNA-dependent RNA polymerase activity in vivo, a large application of glucocorticoid may incur elevation of intracellular cAMP levels.     

Effect of auxins on the formation of ubiquinone by tobacco plant cells in suspension culture

Ubiquinone (UQ) formation in BY-2 tobacco cells was especially promoted by a high concentration of 2,4-D. 2,4,5-T, MCP and NAA also promoted UQ formation in these cells. The UQ content in the cells cultured at high concentrations of 2,4-D was higher than that of controls throughout the culture period. The addition of 2,4-D at an early period in cell growth was very effective in promoting UQ formation, but addition at the stationary phase was ineffective. Cell growth was improved by adding phosphate to the medium but UQ content was decreased. UQ content decreased slowly during subculturing, whereas cell growth recovered gradually.     

Subcellular localization of glycolytic key enzymes in germinating castor bean endosperm

Phosphofructokinase and pyruvate kinase activities in castorbean endosperm increased during germination. Subcellular localizationof pyruvate kinase and phosphofructokinase in germinating endospermtissues was studied by differential and sucrose density gradientcentrifugation techniques. Eighty five percent or more of thepyruvate kinase and phosphofructokinase activities were locatedin cytosol. The remaining activities were mainly detected inproplastids. (Received June 30, 1977; )     

Intracellular hydroxyproline-rich glycoprotein of suspension-cultured tobacco cells

Two soluble glycoproteins containing hydroxyproline were extractedfrom cultured tobacco cells (cell line XD-6S) and purified byion-exchange and gel-filtration chromatography. On DEAR-cellulosecolumn chromatography in the final step of the purification,one was eluted at 90 mM NaCl and the other at 120 mM as singlepeak. Both purified glycoproteins were also sedimented as singlepeak with an ultracentrifugation. The S_20,w values were 6.1for the former and 7.0 for the latter. These glycoproteins were composed of 94% polysaccharide and6% protein in the former, and 87% polysaccharide and 13% proteinin the latter. The sugar moiety consisted of galactose, arabinose,rhamnose, and uronic acid in both. Hydroxyproline accountedfor 12% in the former and 20% in the latter amino acid composition.A high content of alanine in both (14 and 15%) was one of thedistinctive characteristics of these soluble glycoproteins. These intracellular soluble hydroxyproline-containing glycoproteinswere not labelled within 30 min of incubation with ₃H-proline,although the radioactivity was rapidly incorporated (within15 min) into the intracellular macromolecules. (Received February 21, 1978; )     

The role of virulence antigens (VW) in the protection of mice againstYersinia pestis infection

Subcutaneous infection withYersinia enterocolitica harboring plasmid responsible for Ca²⁺ dependence at 37°C induced cell-mediated protective immunity against a lethal challenge withYersinia pestis; the isogenic derivative strain cured from this plasmid subverted the immunity in mice. This is the first identification of the antigen(s) responsible for the induction of cell-mediated protective immunity against the facultatively intracellular bacteria.     

Requirement of the core structure of a complex-type glycopeptide for the binding to immobilized lentil- and pea-lectins

Structural requirements for the binding of oligosaccharides and glycopeptides to immobilized lentil- and pea-lectins were investigated by use of radioactively-labeled glycopeptides and oligosaccharides. The results indicate that an intact 2- acetamido-2-deoxy-β-d-glucopyranosyl residue at the reducing end of a complex-type oligosaccharide is essential for high-affinity binding to lentil lectin-Sepharose but not to concanavalin A-Sepharose and that an asparagine residue is required for the binding of a complex-type glycopeptide to pea lectin-Sepharose. In addition, interaction of a complex-type oligosaccharide with lentil lectin-Sepharose was enhanced by exposure of nonreducing, terminal 2-acetamido-2-deoxy-β-d-glucopyranosyl groups, whereas interaction with pea lectin-Sepharose was enhanced only after exposure of nonreducing, terminal α-d-mannopyranosyl groups.     

2-amino-2-deoxy-D-erythrose in Agaricus bisporus

2-Amino-2-deoxy-D-erythrose was isolated from the cell wall of the fruit body of Agaricus bisporus. The structure of the amino sugar was determined by mass spectrography and 1H-NMR spectrography of its acetylated derivative and by paper chromatographic comparisons with authentic 2-amino-2-deoxy-D-erythrose. This amino sugar is a component of the glycoprotein fraction from the cell wall. Its content in the glycoprotein increased markedly, especially during the ripening stage of the fruit body.     

Hamster cytochrome P-450 IA gene family, P-450IA1 and P-450IA2 in lung and liver: cDNA cloning and sequence analysis.

Two cDNA clones, 2C19 and 4C1, were isolated from a lung cDNA library of 3-methylcholanthrene (MC)-treated hamster by using rat P-450c cDNA as a probe. The cDNA determined from 2C19 and 4C1 was 2,916 bp long and contained an entire coding region for 524 amino acids with a molecular weight of 59,408. The deduced amino acid sequence showed a 85% identity with that of rat P-450c indicating 2C19 and 4C1 encode the hamster P-450IA1 protein. Another cDNA clone, designated H28, was isolated from a MC-induced hamster liver cDNA library by using the hamster lung 2C19 or 4C1 cDNA clone as a probe. H28 was 1,876 bp long and encoded a polypeptide of 513 amino acids with a molecular weight of 58,079. The N-terminal 20 residues deduced from nucleotide sequence of H28 were identical to those determined by sequence analysis of purified hamster hepatic P-450MCI. The high similarity of the nucleotide and deduced amino acid sequences between H28 and P-450IA2 of other species indicated that H28 encoded a P-450 protein which belongs to the P-450IA2 family. Northern blot analysis revealed that the mRNAs for hamster P-450IA1 and IA2 were about 2.9 and 1.9 kb long, respectively. Hamster P-450IA1 mRNA was induced to the same level in lungs as in livers by MC treatment, whereas hamster P-450IA2 mRNA was induced and expressed only in hamster liver.