Direct acid-catalysed transmethylation of lactobacillic acid in lactic acid bacteria

Summary Cellular fatty acids inLactobacillus büchneri were transmethylated with H₂SO₄ catalyst in methanol at elevated temperature. By optimising the reaction time and the amounts of catalyst and methanol used at a fixed temperature it was possible to maximise the lactobacillic acid yield. The yield of lactobacillic acid with this method was better than with the traditional method using base-catalysed saponification followed by HCL-catalysed methylation.     

Phylogeny of Greya (Lepidoptera: Prodoxidae), based on nucleotide sequence variation in mitochondrial cytochrome oxidase I and II: congruence with morphological data

The phylogeny of Greya Busck (Lepidoptera: Prodoxidae) was inferred from nucleotide sequence variation across a 765-bp region in the cytochrome oxidase I and II genes of the mitochondrial genome. Most parsimonious relationships of 25 haplotypes from 16 Greya species and two outgroup genera (Tetragma and Prodoxus) showed substantial congruence with the species relationships indicated by morphological variation. Differences between mitochondrial and morphological trees were found primarily in the positions of two species, G. variabilis and G. pectinifera, and in the branching order of the three major species groups in the genus. Conflicts between the data sets were examined by comparing levels of homoplasy in characters supporting alternative hypotheses. The phylogeny of Greya species suggests that host-plant association at the family level and larval feeding mode are conservative characters. Transition/transversion ratios estimated by reconstruction of nucleotide substitutions on the phylogeny had a range of 2.0-9.3, when different subsets of the phylogeny were used. The decline of this ratio with the increase in maximum sequence divergence among taxa indicates that transitions are masked by transversions along deeper internodes or long branches of the phylogeny. Among transitions, substitutions of A-->G and T-->C outnumbered their reciprocal substitutions by 2-6 times, presumably because of the approximately 4:1 (77%) A+T-bias in nucleotide base composition. Of all transversions, 73%-80% were A<-->T substitutions, 85% of which occurred at third positions of codons; these estimates did not decrease with an increase in maximum sequence divergence of taxa included in the analysis. The high frequency of A<-->T substitutions is either a reflection or an explanation of the 92% A+T bias at third codon positions.      

Interaction of abscisic acid and indole-3-acetic acid-producing fungi with Salix leaves

The molds Botrytis cinerea, Cladosporium cladosporioides, and the yeast Aureobasidium pullulans, isolated from the leaves of three short-rotation Salix clones, were found to produce indole-3-acetic acid (IAA). Abscisic acid (ABA) production was detected in B. cinerea. The contents of IAA and ABA in the leaves of the Salix clones and the amounts of fungal propagules in these leaves were also measured, in order to evaluate whether the amounts of plant growth regulators produced by the fungi would make a significant contribution to the hormonal quantities of the leaves. The content of ABA, and to a lesser degree that of IAA, showed a positive correlation with the frequency of infection by the hormone-producing organisms. The amounts of hormone-producing fungi on leaves that bore visible colonies were, however, not sufficiently high to support the claim that either the fungal production of ABA or IAA would significantly contribute to the hormonal contents of the leaves of the Salix clones. It is therefore suggested that the effect of fungal IAA production on plants is limited to the rhizosphere and that B. cinerea, which is a known pathogen, induces ABA production by the mother plant as a response to physiological stress.Abbreviations ABA abscisic acid - ABA-Me abscisic acid methyl ester - GC-MS-SIM gas chromatography-selected ion monitoring-mass spectrometry - IAA indole-3-acetic acid - IAA-Me indole-3-acetic acid methyl ester Author for correspondence.     

Determination of cis,cis-methylene interrupted polyunsaturated fatty acids in aqueous solutions by lipoxygenase chemiluminescence

The chemiluminescent reaction of luminol during lipoxygenase-catalyzed oxygenations was studied with the purpose of developing a specific luminometric assay for cis,cis-1,4-pentadiene fatty acids directly in aqueous solutions. The addition of picomole levels of either linoleic or arachidonic acids to reaction systems containing 0.04 mM luminol and 40 micrograms/ml of purified soybean lipoxygenase-1 gave light emission curves with a single sharp maximum. Under these conditions the peak heights were linearly dependent on the fatty acid concentration and the detection limit for both of the fatty acids was 2 pmol with a signal to noise ratio of 2. For maximum reproducibility of the assays a procedure for the proper quantitation of the enzyme was developed. The fact that the assay proved to be relatively interference-free was ascribed to the high molar enzyme/substrate ratio (above 1).