Flavonoid glycosides of the roots of Glycyrrhiza uralensis

The structure of a flavanone glycoside from the roots of Glycyrrhiza uralensis has been confirmed as 4′-O-[β-d-apio-d-furanosyl-(1 → 2)-β-d-glucopyranosyl]liquiritigenin. In addition, two known flavonoid glucosides, ononin (a minor component) and liquiritin (a major component), were isolated from the same extract.     

Induction of 3-Hydroxy-3-methylglutaryl CoA Reductase in Potato Tubers after Slicing, Fungal Infection or Chemical Treatment, and Some Properties of the Enzyme

Intact tubers of potato (Solanum tuberosum L. cv. Irish Cobblerand an interspecific hybrid between S. tuberosum and S. demissumcv. Rishiri) contain a very low activity of 3-hydroxy-3-methylglutaryl(HMG)-CoA reductase. The activity increased first in responseto slicing, and again in response to additional treatments suchas inoculation with an incompatible race of Phytophthora infestans,application of a hyphal wall component of the fungus or HgCl₂solution, and then decreased. Both the first and the secondincreases in activity in response to slicing and additionaltreatment with a hyphal wall component to elicit phytoalexinproduction were inhibited by blasticidin S. Properties of HMG-CoAreductase induced by slicing and by additional treatment withHgCl₂ or fungal inoculation were investigated. ² Present address: Faculty of Home Economics, Nagoya Women'sUniversity, Shioji-cho, Mizuho, Nagoya 467, Japan.     

Callus formation from protoplasts of culturedSpinacia oleracea cells

Cell suspensions were initiated from plumule derived calli ofSpinacia oleracea. Some of these cell lines could be maintained in culture for at least three years without a reduced growth rate. A high yield of protoplasts was obtained from the cell suspensions. When protoplasts were cultured in Murashige and Skoog medium with naphthaleneacetic acid and 6-benzyladenine, cell wall formation was observed after three days. The cultured protoplasts produced numerous cell-clusters within two weeks. However only protoplasts isolated from suspensions which were in a rapidly dividing phase were able to divide with a high frequency and give rise to callus colonies.     

Effect of temperature and Zn2+ on isometric contractile properties and electrical phenomena of frog (Rana) and Xenopus skeletal muscle fibers

Effects of temperature and Zn2+ on the isometric contractile properties of toe muscle fibers of Rana catesbeiana and Xenopus laevis were studied. The maximum twitch tension almost doubled when the temperature was lowered from 20 to 4 degrees C in Rana muscles but not in Xenopus muscles, although the duration of action potential in Xenopus muscle was increased slightly more than that seen in the Rana species. The maximum rate of rise of tension was greater in Xenopus muscle than in the Rana muscle, at 20 degrees C. The prolongation of the time-to-peak tension following exposure to low temperature (4 degrees C) was more pronounced in Rana than in Xenopus muscles. These results suggest that the speed of release and reuptake of Ca2+ by the sarcoplasmic reticulum (SR) differs in Rana and Xenopus muscles and that these factors may be related to differences in the SR and the T-tubular morphology. In Rana muscles, Zn2+ prolonged the falling phase of the action potential and potentiated the twitch tension. In Xenopus muscles, Zn2+ marginally prolonged the duration of action potential and the twitch tension was not markedly potentiated. These results indicate that Zn2+ potentiates the twitch by prolonging the action potential and that Rana muscles are more sensitive to the effects of Zn2+.     

Triterpenes from Periandra dulcis roots

Three oleanane triterpenes were isolated from the roots of Periandra dulcis,and identified as 3β-hydroxy-25-al-olean-18-en-30-oic acid (periandric acid I), 3β-hydroxy-25-al-olean-12-en-30-oic acid (periandric acid II) and 3-oxo-25-hydroxy-olean-12-en-30-oic acid. The former two compounds (periandric acids I and II) were identical with the aglycones obtained by hydrolysis of periandrin I and II, respectively and the latter one was a new triterpene.     

Micelle formation of diacylglycerophosphocholines in organic solvents I. effects of the solvents on krafft points

Krafft points of diacylglycerophosphocholines (PC) were measured in alkanes-cyclohexane solutions by differential scanning calorimetry, and it was found that they were regularly increased following the increase in alkane content in the solutions and the chain length of the alkanes. From these results it was deduced that the mixing of PC with alkanes occurred in the gel state of the PC, but not in micelles at higher temperatures above the Krafft points. where micellar solutions are provided. The penetration of alkanes into gel state PC was found to be dominated by Langmuir type interaction, and the affinity of alkanes increases with increasing in chain lengths. Above the Krafft points, the micelle formation was confirmed by using the fluorescence probe technique.     

Location in Muscarinic Acetylcholine Receptors of Sites for [3H]Propylbenzilcholine Mustard Binding and for Phosphorylation with Protein Kinase C

Muscarinic acetylcholine receptors purified from porcine cerebra or atria were covalently labeled with [3H]propylbenzilylcholine mustard ([3H]PrBCM), and then the labeled receptors were subjected to limited hydrolysis with trypsin, V8 protease, and lysyl endopeptidase, followed by analysis involving sodium dodecyl sulfate-polyacrylamide gel electrophoresis, fluorography, autoradiography, or immunostaining. The labeled peptides were located on the basis of their reactivity with antibodies raised against three synthetic peptides with partial sequences of the m1 or m2 receptor, and of their sensitivity to endoglycosidase F, which was taken as evidence that they contain glycosylation sites near the N terminus. The [3H]PrBCM-binding site in both cerebral and atrial receptors was found to be located between the N terminus and the second intracellular loop, because the size of the smallest deglycosylated peptide that contained both the [3H]PrBCM-binding and glycosylation sites was approximately 16 kDa. Cerebral receptors were 32P-phosphorylated with protein kinase C, and the major phosphorylation sites in cerebral muscarinic receptors were found to be located in a C-terminal segment including a part of the third intracellular loop, because a 32P-labeled peptide of 12-14 kDa reacted with anti-(m1 C-terminal peptide) antiserum. The presence of an intramolecular disulfide bond, probably between Cys 98 and Cys 178 in the first and second extracellular loops, respectively, was suggested by the finding that a peptide of approximately 17 kDa containing the [3H]PrBCM-binding site, but not the glycosylation sites, was partly converted to a peptide of approximately 12 kDa on treatment with beta-mercaptoethanol.     

Analysis of an ABA-responsive rice gene promoter in transgenic tobacco

We have analyzed in transgenic tobacco the expression of a chimeric gene containing 5 sequences of the rice rab-16B gene fused to the -glucuronidase (GUS) reporter gene. This construct, a translational fusion (–482 to +184) including 14 amino acids of the RAB-16B protein, is expressed only in zygotic and pollen-derived embryos. In zygotic embryos, GUS activity begins to accumulate 10 days after flowering (daf), and increases until seed maturation at 25 daf. Immunological measurements of endogenous abscisic acid (ABA) accumulation in these seeds showed a close parallel between hormone levels and GUS activity. However, GUS activity could not be reproducibly induced by treatment of immature embryos with ABA (10 M). Neither GUS activity nor GUS mRNA could be detected in leaves of transgenic tobacco even after ABA treatment. In contrast, GUS activity could be induced to high levels in pollen-derived embryos by treatment with ABA. Our results show that 482 bp of 5 sequences of the rice rab-16B promoter can confer in transgenic tobacco developmentally regulated expression in embryos but not ABA-responsive expression in vegetative tissues.