Promotion of Plant Cell Division by an Epidermal Growth Factor

In some specified treatments, an epidermal growth factor (EGF)promoted adventitious root formation in epicotyl cuttings ofVigna angularis. The number of the roots induced in cuttingstreated with 0.1 mg liter^-1 EGF during the first 24 h and with210^-4 M IAA during the second 24 h was 15% greater than thatof the roots in cuttings treated without EGF and with IAA. Analysisof the optimum timing of EGF application was performed by dividingthe first 24 h period into three sequential 8 h periods (0–8h, 8–16 h and 16–24 h). The most effective timeperiods in terms of the root formation were 8–16 h and16–24 h. The 0–8 h period was ineffective with respectto the formation. When carrot suspension cells were culturedfor 15 days at a very low cell density (1,000 cells/3 ml Murashigeand Skoog's medium) with more than 0.1 mg liter^-1 EGF, cellnumbers were 72% higher than those cultured without EGF. Theseresults suggest that EGF promotes cell division of plants. (Received October 5, 1992; Accepted May 24, 1993)     

Methyl jasmonate induces anthocyanin accumulation in <Emphasis Type="Italic">Gynura bicolor</Emphasis> cultured roots

Gynura bicolor DC., a traditional vegetable in Japan, is cultivated as Kinjisou and Suizenjina in Ishikawa and Kumamoto prefectures, respectively. The adaxial side of the leaves of G. bicolor grown in a field is green, and the abaxial side is reddish purple. It has been reported that these reddish purple pigments are anthocyanins. Although we established a culture system of G. bicolor, the leaves of G. bicolor plants grown under our culture conditions showed green color on both sides of all leaves. We investigated the effects of phytohormones and chemical treatments on anthocyanin accumulation in cultured plants. Although anthocyanin accumulation in the leaves was slightly stimulated, anthocyanins accumulation in the roots of the cultured plant was induced remarkably by 25–50 μM methyl jasmonate (MJ) treatment. This induction was affected by light irradiation and sucrose concentration in the culture medium. However, salicylic acid (SA) and 1-aminocyclopropane-1-carboxylic acid did not induce anthocyanin accumulation in roots. And then, combinations of MJ and SA or MJ and AgNO₃ did not stimulate the anthocyanin accumulation in the root as found in the case of treatment by MJ solely.     

Complementary double-stranded helical oligomers bearing achiral bifunctional groups that catalyze asymmetric aldol reaction

Two novel chiral dimer and trimer strands composed of m-terphenyl groups linked through p-diethynylbenzene units with the chiral amidine group and achiral piperazine group introduced at the terminus or center of the strands, respectively, and its complementary achiral carboxylic acid dimer and trimer were synthesized. The complementary chiral/achiral strands form an excess-handed double-helical structure as supported by intense split-type Cotton effects in the absorption regions of the conjugated backbones biased by the chiral amidinium–carboxylate salt bridges. The double-helical trimer was found to catalyze the direct aldol reaction of cyclohexanone with 4-nitrobenzaldehyde and produce the products with a moderate enantioselectivity despite the fact that the catalytically active bifunctional piperazine/carboxylic acid pair introduced in the middle is achiral, indicating the key role of the one-handed double-helical framework for supramolecular bifunctional organocatalysis.     

Anabolic utilization of steroid hormones in Helicobacter pylori

In this study, we have demonstrated that Helicobacter pylori absorbs a steroid prehormone (pregnenolone) and two androgens (dehydroepiandrosterone and epiandrosterone), glucosylates these steroids, and utilizes glucosyl-steroid hormone compounds as the membrane lipid components. The only common structure among the steroid prehormone and the two androgens is a 3β-OH in the steroid framework. Our results indicate that the 3β-OH in the steroid hormones is a crucial conformation required for steroid glucosylation by H. pylori . In addition, we found that H. pylori absorbs and holds estrogens possessing 3-OH (estrone and estradiol) into the membrane. The effective absorption of estrogen into the membrane appeared to be controlled by the number of hydroxyl groups modifying the steroid framework. In contrast, H. pylori induced neither membrane absorption nor glucosylation of the other steroid hormones possessing 3=O (progesterone, androstenedione and testosterone) or 3α-OH (androsterone). These results indicate that H. pylori selectively absorbs 3β-OH and 3-OH steroid hormones, and utilizes only 3β-OH steroid hormones as the materials for glucosylation.     

Isolation and identification of littorine from hairy roots of Atropa belladonna

A hairy root clone (M8) of Atropa belladonna, producing high levels of tropane alkaloids, was established by transformation with Agrobacterium rhizogenes (MAFF 03-01724). Littorine, an intermediate of tropane alkaloids, was detected by high-performance liquid chromatography and gas chromatography-mass spectrometry in the alkaloid fraction of the hairy roots and identified by nuclear magnetic resonance analysis. Littorine was also detected in the non-transformed root culture of A. belladonna. Received: 18 March 1998 / Revision received: 15 June 1998 / Accepted: 3 August 1998     

Infectivity suppressing and virus-binding activities of a membrane material isolated from tobacco leaves.

TMV binding substance (R) was isolated from a tobacco leaf membrane fraction and was purified by extraction with organic solvents and by column chromatography. Experimental results suggest that the binding of R with TMV results in inactivation of TMV. When tobacco leaves were inoculated with the R-TMV complex, it was found that the formation of polysome containing infecting viral RNA was inhibited. Model experiments showed that the mode of R-TMV adsorption to the membrane is different from that of TMV adsorption and that stripping of coat protein from TMV by SDS was inhibited by R. A possible explanation for the mechanism of this inhibition by R is that the R-TMV complex follows a pathway which does not lead to establishment of infection. Although less efficient, R was still active when it was applied after virus inoculation. Due to its affinity to coat protein, R might also interfere with a later process of viral multiplication.     

DNA recognition by synthetic peptides as a model for the dimeric proteins.

A Chiral template possessing a C2 axis has been utilized to study an effect in the dimer formation of oligopeptides. Oligopeptide rich in basic amino acids are used as subunits that would interact with DNA, and the subunits are aligned according to the C2 axis of the template. Synthesis, characterization and DNA binding study of these dimeric peptides will be discussed.