Heterogeneity of lipoteichoic acid detected by anion exchange chromatography

A complex polydispersity became apparent when the poly(glycerophosphate) lipoteichoic acid of Enterococcus faecalis was chromatographed on DEAE-sephadex. The chain length varied between 13 and 33 glycerophosphate residues per lipid anchor. In parallel, the extent of chain glycosylation increased from 0.2 to 0.4 diglucosyl residues per glycerophosphate unit. Substitution with D-alanine ester showed a reverse distribution dropping with increasing chain length from 0.53 to 0.23 mol D-alanine per mol phosphorus. Variations in the fatty acid composition were also observed. The results extent and modify the current picture of lipoteichoic acid biosynthesis. They further suggest that during infection the mammalian organism may be confronted particularly with long-chain less hydrophobic molecular species.     

The metabolism of lactose byClostridium acetobutylicum

Summary Acetone and butanol biosynthesis byClostridium acetobutylicum ATCC 824 was affected by lactose concentration and by agitation during the fermentation. At 1% and 3% lactose concentrations acid production predominated, while butanol production predominated at 5% lactose concentration. Higher solvent production was observed in fermentors without agitation than in fermentors with agitation.     

Effect of ethylene on sanguinarine production from Papaver somniferum cell cultures

A Papaver somniferum cell line capable of producing sanguinarine equivalent to 3% of cell dry weight was used to determine if ethylene was involved in signalling the biosynthesis of this alkaloid. A 3.3-fold increase in ethylene emanation from these cell suspension cultures was observed 7 h after elicitation with a Botrytis fungal homogenate. The rate of ethylene release then decreased to near zero after 48 h, suggesting that a pulse of ethylene production may be involved in sanguinarine production. However, sanguinarine biosynthesis was not promoted when either the ethylene precursor, 1-aminocyclopropane-1-carboxylic acid (ACC), or the ethylene releasing agent, 2-chloroethylphosphonic acid (ethephon), was added to the culture. These results strongly suggest that ethylene is not intimately involved in the production of sanguinarine from Papaver somniferum cell cultures or in the transduction of the elicitation event.Abbreviations ACC 1-aminocyclopropane-1-carboxylic acid     

Light-regulated Arabidopsis ACBP4 and ACBP5 encode cytosolic acyl-CoA-binding proteins that bind phosphatidylcholine and oleoyl-CoA ester

In Arabidopsis thaliana, six genes encode acyl-CoA-binding proteins (ACBPs) that show conservation of an acyl-CoA-binding domain. These ACBPs display varying affinities for acyl-CoA esters, suggesting of different cellular roles. We have recently reported that three members (ACBP4, ACBP5 and ACBP6) are subcellularly localized to the cytosol by biochemical fractionation, confocal microscopy of transgenic Arabidopsis expressing autofluorescence-tagged fusions and immuno-electron microscopy using ACBP-specific antibodies. In this study, we observed by Northern blot analysis that ACBP4 and ACBP5 mRNAs in rosettes were up-regulated by light and dampened-off in darkness, mimicking FAD7 which encodes omega-3-fatty acid desaturase, an enzyme involved in plastidial lipid metabolism. Results from in vitro binding assays indicate that recombinant ACBP4 and ACBP5 proteins bind [¹⁴C]oleoyl-CoA esters better than recombinant ACBP6, suggesting that light-regulated ACBP4 and ACBP5 encode cytosolic ACBPs that are potential candidates for the intracellular transport of oleoyl-CoA ester exported from the chloroplast to the endoplasmic reticulum for the biosynthesis of non-plastidial membrane lipids. Nonetheless, His-tagged ACBP4 and ACBP5 resemble ACBP6 in their ability to bind phosphatidylcholine suggesting that all three ACBPs are available for the intracellular transfer of phosphatidylcholine.     

Enzymic synthesis of o-succinylbenzoyl-CoA in cell-free extracts of anthraquinone producing Galium mollugo L. cell suspension cultures

o-Succinylbenzoic acid (OSB) is an intermediate in the biosynthesis of shikimatederived anthraquinones. The cell free activation of o-succinylbenzoic acid in extracts of anthraquinone producing cells of Galium mollugo L. is demonstrated for the first time. This activation depends on the presence of ATP, coenzyme A and Mg²⁺. The o-succinylbenzoic acid coenzyme A ester was identified by converting it to 1,4-dihydroxy-2-naphthoic acid by a bacterial enzyme, viz. naphthoatesynthase. It is thus demonstrated that the o-succinylbenzoic acid coenzyme A ester derived from bacteria and from Galium mollugo cells are identical.     

Cloning a mutatedtrp operon for the biosynthesis of an antibiotic agent

Summary Plasmid pCG8 containing a mutatedtrp operon was constructed and introduced into anEscherichia coli host for increasing tryptophan biosynthesis. Since tryptophan is a biosynthetic precursor of pyrrolnitrin, the mutated trp operon was inserted into aPseusdomonas vector pME290 to obtain the plasmid pCG12, and then was introduced intoPseudomonas pyrrocinia for enhancing the pyrrolnitrin synthesis. Data showed that the production of pyrrolnitrin of the transformed strain was five-times greater than that of the parental strain.     

Effect of the genes B and Pl on anthocyanin synthesis in maize endosperm culture

B and Pl are two genes involved in anthocyanin biosynthesis in maize (Zea mays) plant tissues. In this work the effect of B and Pl on pigment accumulation is analyzed in endosperm tissues, either cultured in vitro or scraped off from the seed. The results obtained indicate that the two genes play a different role in callus pigmentation: B exerts a qualitative change in pigment composition, while Pl controls the rate of pigment accumulation in the callus. Anthocyanin synthesis in all strains analyzed appears to be light independent. Two cases of instability in pigment production arisen in the endosperm cultures are described and discussed in relation to epigenetic variation in secondary metabolite content in plant tissue culture.Abbreviations BEAF Benzene/ethyl acetate/formic acid (40:10:5) - 2-4D 2,4-dichlorophenoxyacetic acid - Wi initial weight - Wt total weight     

Syncytium gene expression in Glycine max[PI 88788] roots undergoing a resistant reaction to the parasitic nematode Heterodera glycines

The plant parasitic nematode, Heterodera glycines is the major pathogen of Glycine max (soybean). H. glycines accomplish parasitism by creating a nurse cell known as the syncytium from which it feeds. The syncytium undergoes two developmental phases. The first is a parasitism phase where feeding sites are selected, initiating the development of the syncytium. During this earlier phase (1–4 days post infection), syncytia undergoing resistant and susceptible reactions appear the same. The second phase is when the resistance response becomes evident (between 4 and 6 dpi) and is completed by 9 dpi. Analysis of the resistant reaction of G. max genotype PI 88788 (G. max_{[PI 88788]}) to H. glycines population NL1-RHg/HG-type 7 (H. glycines_{[NL1-RHg/HG-type 7]}) is accomplished by laser microdissection of syncytia at 3, 6 and 9 dpi. Comparative analyses are made to pericycle and their neighboring cells isolated from mock-inoculated roots. These analyses reveal induced levels of the jasmonic acid biosynthesis and 13-lipoxygenase pathways. Direct comparative analyses were also made of syncytia at 6 days post infection to those at 3 dpi (base line). The comparative analyses were done to identify localized gene expression that characterizes the resistance phase of the resistant reaction. The most highly induced pathways include components of jasmonic acid biosynthesis, 13-lipoxygenase pathway, S-adenosyl methionine pathway, phenylpropanoid biosynthesis, suberin biosynthesis, adenosylmethionine biosynthesis, ethylene biosynthesis from methionine, flavonoid biosynthesis and the methionine salvage pathway. In comparative analyses of 9 dpi to 6 dpi (base line), these pathways, along with coumarin biosynthesis, cellulose biosynthesis and homogalacturonan degradation are induced. The experiments presented here strongly implicate the jasmonic acid defense pathway as a factor involved in the localized resistant reaction of G. max_{[PI 88788]} to H. glycines_{[NL1-RHg/HG-type 7]}.     

Acid stress damage of DNA is prevented by Dps binding in <Emphasis Type="Italic">Escherichia coli</Emphasis>O157:H7

Background  

Acid tolerance in Escherichia coli O157:H7 contributes to persistence in its bovine host and is thought to promote passage through the gastric barrier of humans. Dps (DNA-binding protein in starved cells) mutants of E. coli have reduced acid tolerance when compared to the parent strain although the role of Dps in acid tolerance is unclear. This study investigated the mechanism by which Dps contributes to acid tolerance in E. coli O157:H7.     

Sequence characterization of alleles Gpi1-s a and Gpi1-s b at the glucose phosphate isomerase structural locus

The sequences of alleles Gpil-s ^a and Gpi1-s ^b at the glucose phosphate isomerase structural locus have been determined from cDNA of the mouse inbred strains 101/H Gpi1-s ^a and C3H/HeH Gpi1-s ^b by TR PCR and direct sequencing of the amplified products. Four individual nucleotide differences were observed between the two alleles. The difference at amino acid residue 94, (Gpi1-s ^a GAT Asp, Gpi1-s ^b AAT Asn) may account for the differing electrophoretic migration, isoelectric point, and thermostability of the two alleles. Two of the other observed differences in the coding region (amino acid residue 12 Leu, Gpi1-s ^a CTC, Gpi1-s ^b CTG and amino acid residue 17 Arg, Gpi1-s ^a CGC, Gpi1-s ^b CGT) are silent and do not affect the predicted amino acid residues on translation. The fourth observed difference is located within the 3 noncoding sequences of the cDNA. The change at amino acid residue 94 is associated with the presence of a Hinf1 restriction site in Gpi1-s ^b, which is absent in Gpi1-s ^a, and may be a useful method for determining this marker.     

Non-polluting wood and pulp delignification: Biomimetic ligninase system

Summary We report the delignification ofPinus radiata D Don,Eucalyptus globulus andEucalyptus grandis woods (formic acid treated and untreated) by 2 h treatment with a hemin/hydrogen peroxide system. The untreated chips and sawdust ofE. globulus were 30% and 50% delignified respectively. No significant effects were found forP. radiata sawdust;P. radiata treated chips (organosolv pulp) did not show any further delignification upon hemin/peroxide action, 25% delignification was achieved in untreated chips. In the case ofE. grandis untreated wood the delignification was better in sawdust than in chips, but in smaller percentage than in the otherEucalyptus species. This relation is maintained in substrates, treated with formic acid or untreated. The delignification of chips in both species ofEucalyptus was improved when they were pre-treated with formic acid. The loss of lignin in theE. grandis andE. globulus sawdust (pre-treated with formic acid) was 79% and 75% respectively.     

Biosynthesis of rutacridone in tissue cultures of Ruta graveolens L.

The dihydrofuroacridone, rutacridone, is the main alkaloid in tissue cultures of Ruta graveolens L. strain R-19. The biosynthesis of this particular acridone alkaloid was investigated by using calluses and suspension cultures of strain R-19. Anthranilic acid is specifically incorporated into ring A of rutacridone. Some further evidence was provided that acetate via a polyketide is involved in acridone biosynthesis. Mevalonic acid gave a poor incorporation into rutacridone. Thus the origin of the isopropyldihydrofuran moiety of the investigated alkaloid is still obscure.     

Baeyer-Villiger oxidation of bicyclic ketones by Cylindrocarpon destructans ATCC 11011

Baeyer-Villiger oxidation of bicyclic ketones1a,1b and4 using whole cell suspensions of the fungusCylindrocarpon destructans was found to proceed quantitatively and in case of substrate (±)-1b a moderate enantioselectivity was observed leading to (1S,6R)-1b and (1R,6S)-2b with 28% and 27% e.e., respectively.     

Gypsy/Ty3-class retrotransposons integrated in the DNA of herring,tunicate, and echinoderms

Eight new examples of retrotransposons of the Gypsy/Ty3 class have been identified in marine species. A 525-nt pol gene-coding region was amplified using degenerate primers from highly conserved regions and has extended the range of recognition of Gypsy/Ty3 far beyond those previously known. The following matrix shows the percentage AA divergence of the translations of this segment of the pol gene coding region. Spr2 Strongylocentrotus purpuratus, sea urchin 39 Por2 Pisaster ochraceus, starfish 46 45 Cprl Clupea pallasi, herring 51 52 41 Cirl Ciona intestinalis, tunicate bar52 49 49 55 P. orchraceus, starfish 55 60 60 62 62 Spr3 S. purpuratus, sea urchin 55 61 60 63 61 24 Tgrl^* Tripneustes gratilla, sea urchin 56 61 60 63 58 26 27 Lvrl^* Lytechinus variegatus, sea urchin 57 62 60 64 62 27 10 29 Sprl^* S. purpuratus 58 61 62 65 61 15 27 30 31 Spr4 S. purpuratus 72 72 74 75 72 73 72 72 73 72 Por3 P. ochraceus The underlines separate three groups of retrotransposons that can be recognized on the basis of this amino acid sequence. The new upper group shows surprising amino acid sequence similarity among members from the DNA of herring, sea urchin, starfish, and a tunicate. For example, the herring element differs by only 41 % from the Ciona element and 46% from the sea urchin element. The group between the lines includes members close to previously known elements (marked by asterisks) and has so far been found only in sea urchins. The two upper groups differ from each other by 55–60% and yet members of both groups (e.g., Sprl and Spr2) are integrated into the DNA of one species-S. purpuratus. Below the lower underline is listed the only known representative of a very distant group, which occurs in starfish DNA. In spite of large divergence, amino acid sequence comparisons indicate that all of the elements shown in the array are members of the LTR-containing class of retrotransposons that includes Gypsy of Drosophila and Ty3 of yeast. Of all known mobile elements this class shows the closest sequence similarity to retroviruses and has the same arrangement of genes as simpler retroviruses.Correspondence to: R.J. Britten