Effects of serial subculture in vitro on the endogenous levels of indole-3-acetic acid and abscisic acid and rootability in microcuttings of ‘Jonathan’ apple

Proliferating axillary shoots of the difficult-to-root apple cultivar Jonathan acquired an enhanced ability to form adventitious roots with increasing number of subcultures in vitro. The transition between the difficult-to-root and the easy-to-root condition occurred at the fourth subculture.Endogenous levels of free IAA and ABA in shoot tissues were analysed by gas chromatography/mass spectrometry/single ion monitoring (GC/MS/SIM) using negative ion chemical ionisation. Tissues from the mother plants grown in the glasshouse contained more IAA and ABA than those from tissue-culture material. After establishment in vitro there was no variation in the IAA content throughout the subcultures but a decrease in ABA content was observed after the fourth transfer. The IAA/ABA ratio increased from 0.2 in difficult-to-root shoots from the initial culture up to 0.7 in easy-to-root shoots from the long-term subculture.     

Second-harmonic generation in monolayers of hemicyanine dyes at the air/water interface: Observation of chemical degradation

In situ studies of second-harmonic generation (SHG) in monolayers of pure hemicyanine dyes and their mixtures with arachidic acid at the air/water interface were performed. The studies revealed an unexpected chemical instability of the hemicyanine dyes involving a cleavage of the stilbene double bond when deposited onto the water surface. This reaction occurred especially rapidly in the presence of the arachidic acid. Dilution with arachidic acid did not lead to a significant enhancement of the harmonic intensity.     

Some common properties of lectins from marine algae

Twelve kinds of lectins isolated from four species of marine algae, Boodlea coacta (Chlorophyta) and Hypnea japonica, Carpopeltis flabellata and Solieria robusta (Rhodophyta), were compared for their chemical and biological properties. These lectins were proteins or glycoproteins, similar to terrestrial plant lectins. However, unlike most terrestrial plant lectins, they had a small molecular size (4,200 to 25,000 daltons), were mostly monomeric, and had no affinity for monosaccharides. They strongly agglutinated trypsin-treated rabbit erythrocytes, and their activities commonly were inhibited by glycoproteins bearing N-glycans. From hemagglutination-inhibition tests with various glycoproteins and related compounds, it was found that B. coacta lectins recognize high-mannose N-glycans; H. japonica lectins complex N-glycans, and C. flabellata and S. robusta lectins recognize both types of N-glycans.     

Studies on the properties of the variants of gamma-glutamyl transpeptidase in human urine

Both the high molecular weight and the low molecular weight variants of urinary Y-glutamyl transpeptidase, displayed transpeptidase (pH optimum 8.6) and autotrans-peptidase (pH optimum 9.4) activities. Iodoacetamide inhibited the transpeptidase activity more efficiently than the autotranspeptidase activity with respect to both variants of Y-glutamyl transpeptidase. The high molecular weight form utilized L-glutamine as a better acceptor than L-cystine during the transpeptidation reaction whereas the reverse was the case with the low molecular weight variant. While phenylmethylsulphonyl fluoride-treated enzymes retained full activitiesper se, addition of maleic acid to the modified enzyme was found to inhibit the catalytic activities indicating a maleic acid-induced conformational change of the modified enzyme.     

Chemical modifications of actin: effects on interaction with deoxyribonuclease I

Maleylation of lysine residues, nitration of tyrosine residues or modification with 2,3-butanedione or 1,2-cyclohexanedione of arginine residues on actin resulted in a loss of polymerizability of the modified actin. However, only lysine modification produced a complete loss of the deoxyribunuclease I inhibitory ability of actin at low degrees of modification. By the level of one modified lysine per actin monomer, the samples completely lost polymerizability and lost 65% of their inhibitory power against deoxyribonuclease I-catalysed hydrolysis of DNA. By two lysines modified per actin, all inhibitory activity was lost. One lysine residue on actin apparently overlaps both an actin action contact site and an actin-deoxyribnuclease 1 contact site, offering a suggestion as to how deoxyribonuclease I blocks actin polymerization.     

Synthesis and relative stereochemistry of the four mercapturic acids derived from styrene oxide and N-acetylcysteine

The chemical reaction between (±)-styrene oxide and N-acetylcysteine produces both positional isomers ($\text{1}$ and $\text{2}$) as a mixture of diastereoisomers with a preference for the benzylic thioether isomer $\text{1}$ (2 : 1). Synthesis of the mercapturic acid conjugates from either (+)- or (?)-styrene oxide produces only two of the four possible stereoisomers. The single diastereoisomers of $\text{1}$ and $\text{2}$ were separated by high pressure liquid chromatography (HPLC) and identified by ¹H- and ¹³C-nuclear magnetic resonance (NMR). The relative stereochemistry at the benzylic carbon center of the mercapturic acid conjugates was assigned on the basis of the established chemical correlation between optically pure styrene oxide and its precursor mandelic acid, and considerations on the mechanism of ring opening of epoxides by sulfur nucleophiles. The stereochemical definition of the isomers $\text{3}$–$\text{6}$ should prove useful in investigations of the biotransformation of the glutathione (GSH) conjugates of styrene oxide.     

Efficacy of Oxamyl Against Heterodera schachtii on Cabbage

The efficacy of oxamyl in controlling Heterodera schachtii on cabbage was determined by applying various contbinations of soil drenches at 6.7 kg (a.i.)/ha and foliar sprays at 0.04 kg (a.i.)/100 liters of water to cabbage seedlings. Pretransplant drenches provided some control of H. schachtii over a 13-week period. A single foliar spray of oxamyl 1 week before transplanting apparently prevented penetration of H. schachtii larvae; post-transplant sprays were relatively ineffective. A pretransplant or transplant drench combined with a foliar application 2 weeks after transplanting provided the most effective control. The effectiveness of drenches plus post-transplant sprays is probably due to the spray augmenting the action of the drench in inhibiting the development of larvae after penelration.     

Structure des caboxines: Alcaloïdes oxindoliques du Cabucala fasciculata

The structures of three new 11-monomethoxy pentacyclic oxindole alkaloids have been elucidated by chemical correlations with reserpinine: caboxine-A was assigned to the allo C₁₉-méthyl α series: 3S, 4R, 7S, 19S; isocaboxine-A and B to the epi-allo C₁₉-methyl α series and have, respectively, the following configurations 3R, 4S, 7S, 19S and 3R, 4S, 7R, 19S.