The relation of 3-deoxy-2-oxo-octonate to the serological and physical properties of a lipopolysaccharide from a rough strain of Escherichia coli

1. A water-soluble preparation of lipopolysaccharide was isolated from the extracellular lipopolysaccharide-phospholipid-protein complex formed by Escherichia coli A.T.C.C. 12408. 2. Heating at 100 degrees and pH4.6 caused a rapid decrease in serological activity concomitant with the release of 3-deoxy-2-oxo-octonate; aggregation of the molecules also occurred. 3. Further evidence that the release of 3-deoxy-2-oxo-octonate is related to loss of serological activity was obtained by comparing the effects of heating for 1hr. at 100 degrees and pH values between 5.0 and 9.0; detectable changes still occurred at pH7.5. 4. 3-Deoxy-2-oxo-octonate was isolated from the products of hydrolysis of lipopolysaccharide and shown to be an effective inhibitor of the precipitin reaction between lipopolysaccharide and homologous antiserum. 5. The possibility that 3-deoxy-2-oxo-octonate is joined to the lipopolysaccharide through a phosphodiester linkage is discussed.     

Effects of detrending and rescaling on correspondence analysis: solution stability and accuracy

Detrending and non-linear axis rescaling potentially improve the accuracy of gradient recovery in correspondence analyses but also reduce the stability or consistency of solutions. Variation among bootstrapped ordination solutions was compared across methods in analyses of both field and simulated data. Solution accuracy, measured with mean squared errors from Procrustes analysis, was compared using simulated data with known structure.Standard detrending-by-segments combined with non-linear rescaling entailed some cost in solution stability, but could improve the accuracy of solutions for long gradients. Without non-linear rescaling these solutions were usually less stable and less accurate. Although detrending-by-polynomials might be preferable on other grounds, it did not produce more accurate or stable solutions than detrending-by-segments.Abbreviations CA = correspondence analysis - DCA = detrended correspondence analysis - MSE = Procrustes mean squared error statistic - SD = standard deviation units of species turnover - SRV = scaled variance in species ranks     

Immunochemical comparison of membrane-associated and secreted arabinogalactan-proteins in rice and carrot

Arabinogalactan-proteins (AGPs) occurring in suspension-cultured rice (Oryza saliva L.) cells, their conditioned medium and at the rice root apex were investigated using monoclonal antibodies and the AGP-binding -glucosyl Yariv reagent ( GlcY). A monoclonal antibody, LM2, was generated that recognized an acidic carbohydrate epitope common to two soluble AGPs occurring in the conditioned medium of proliferating rice cells, membrane-associated AGPs (rmAGP) in the cultured cells and two AGPs at the rice root apex. In addition, LM2 recognized AGPs secreted by suspensioncultured carrot (Daucus carota L.) cells. The two AGPs of the rice culture medium, srAGP1 and srAGP2, were discriminated by their mobilities during sodium dodecyl sulfate-polyacrylamide gel electrophoresis, reaction with GlcY, the presence of arabinogalactan epitopes and anion-exchange chromatography. The association of rmAGP with the plasma membrane was investigated by Triton-X-114/aqueous partitioning of both microsomal and plasma-membrane preparations and rmAGP was found to partition into the detergent phase, indicating that AGPs are hydrophobic plasma-membrane proteins in rice. This was in contrast to plasma-membrane AGPs of suspension-cultured carrot cells that partitioned into the aqueous phase. At the rice root apex most of the AGP was associated with the microsomal fraction and also partitioned into the detergent phase, although a distinct highmolecular-mass AGP entered the aqueous phase.Abbreviations AGP arabinogalactan-protein - GlcY -glucosyl Yariv reagent - ELISA enzyme-linked immunosorbent assay We gratefully acknowledge support from the Leverhulme Trust, the UK Biotechnology and Biological Sciences Research Council and the Royal Society.     

Localization of the two major allergens in rye-grass pollen using specific monoclonal antibodies and quantitative analysis of immunogold labelling

Summary The intracellular localization of the two major allergens, Lol p I and Lol p IX, in rye-grass anthers was examined using monoclonal antibodies FMCA1 (specific for Lol p I) and FMCA7 (specific for Lol p IX) with immunocytochemical techniques and quantitative analysis. A newly developed anhydrous fixation technique in a mixture of glutaraldehyde, paraformaldehyde and 2, 2-dimethoxypropane followed by embedding in LR Gold resin resulted in both improved infiltration of pollen grains compared with existing techniques and the localization of these water-soluble antigens in their original sites compared with diffusion artefacts following aqueous methods. After anhydrous fixation, Lol p I was predominantly located in the electron-opaque regions of the cytosol of the vegetative cell of the tricellular pollen grains (24 counts m^-2), whereas Lol p IX was detected mainly within starch granules (16 counts m^-2). For both Lol p I and Lol p IX, similar labelling was detected in the cells of the endothecium and middle layer (18 counts m^-2), but none was found in the tapetal cells or orbicules.     

Pollen allergens: development and function

Pollen allergens interact with the human immune system and the resulting IgE antibodies provide specific probes for their identification and characterisation. In one case, grass allergenic proteins are expressed late in pollen development coincident with the laying down of reserves. Sequence similarity of allergens has indicated possible functions for some allergens. The major birch pollen allergen shows sequence similarity with pathogenesis-related proteins, which form a secondary response in plant host-pathogen interactions and show anti-microbial activity. Some allergens of unknown function are cysteine-rich proteins, while some others have cysteine-rich regions; for example, the major allergen from rye-grass pollen, Lol p 1, has a cysteine-rich N-terminal region, while at the C-terminal region four tryptophan residues together with tyrosine and phenylalanine residues resemble those of cellulose- or sugar-binding domains of other proteins. Several pollen allergens show sequence similarity to cell wall-associated enzymes, while others show hydrolytic enzyme activity often associated with cell walls.