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Biomedical subjects

R B Knox

Publications and source records attributed to R B Knox.

At least 55 records · Page 3Linked to original sources
PubMed1984

Pollen-pistil interactions in interspecific crosses of Populus (sections Aigeiros and Leuce): pollen adhesion, hydration and callose responses.

Intersectional crosses between species of sections Aigeiros (Populus deltoides, P. X euramericana or P. nigra) and Leuce (P. alba or P. tremuloides) are known to be reciprocally incompatible. The site of pollen tube arrest is on the stigma surface in pollinations between pistils of section Leuce and pollen of section Aigeiros; tubes failed to penetrate the stigma surface. In reciprocal matings, pollen of section Leuce germinated and tubes penetrated the stigma and style, where arrest occurred. Rejection may be accompanied by swelling of the tube tips, and callose plug formation. In the cross between P. deltoides and P. alba a callose response was detected in the cell walls of the transmitting tissue, adjacent to the rejected pollen tubes.

Microscopy, Electron, Scanning↗
PubMed1982

Immunocytochemical localization of water-soluble glycoproteins, including group 1 allergen, in pollen of ryegrass, Lolium perenne, using ferritin-labelled antibody.

The cellular sites of the glycoproteins Group 1 allergen (glycoprotein 1) and Antigen A (glycoprotein 2) in mature ryegrass pollen have been investigated by immunoelectron microscopy. Radioimmunoassays confirm previous findings of cross-reactivity between the purified glycoprotein antigens at the high immunoglobulin G (IgG) concentrations used for localization. Freeze-drying of anthers followed by anhydrous processing has been employed because of the water solubility and mobility of the glycoproteins. A double-embedding technique has been developed. This involves, first, embedding anthers in the water-soluble plastic resin JB-4, sectioning and incubating in ferritin-labelled antisera by the indirect method. The sections are then embedded in Spurr's resin for ultra-thin sectioning. Both glycoproteins are found in the following sites: (1) exine and intine wall layers; (2) pollen cytoplasm; (3) the orbicules and anther loculus; and (4) the anther cuticle. In the exine arcades and surface and in the anther loculus, the ferritin label is bound to pollenkitt. The finding that the glycoproteins are in similar sites is predictable in view of the cross-specificity of the antisera. The extent of antibody penetration of the plastic sections has been examined; labelling is confined to cut grains and absent from intact grains.

Allergens↗
PubMed1982

Cross-reactivity between Acacia (wattle) and rye grass pollen allergens. Detection of allergens in Acacia (wattle) pollen.

Immunoglobulin E (IgE), directed against components of Acacia (wattle) pollen, has been detected by radioallergosorbent tests (RAST) in the sera of some children and adults who develop allergic symptoms in the presence of flowering Acacia trees in Australia. All these subjects also had high levels of IgE directed against Lolium perenne (rye grass) pollen. Inhibition by RAST showed that most of the IgE molecules which bound to Acacia pollen components also bound to L. perenne pollen extracts, and to Glycoprotein 1, the major allergen of L. perenne pollen. In these assays, the allergens have been immobilized on polyvinyl chloride microtitre trays: the sensitivity of this approach is compared to that of commercial RAST kits.

Acacia↗
PubMed1981

Immunofluorescent localization of two water-soluble glycoproteins including the major allergen from the pollen of ryegrass, Lolium perenne.

Two major glycoproteins have been localized in sectioned grains of ryegrass pollen by direct and indirect immunofluorescence methods using Fluorescein isothiocyanate (FITC)-labelled IgG fractions of antisera. These glycoproteins are the major allergen, Group 1 allergen, and a principal antigen, Antigen A. Four methods of fixation were employed: freeze-drying, methanol, 2.5% glutaraldehyde and 4% paraformaldehyde for 1 h at 4 degrees C. The post-embedding staining technique of immunocytochemistry was used: anthers were embedded directly, or after dehydration, in JB-4 plastic resin and antibody reacted with sectioned pollen. The effects of these fixatives on the antibody combining sites of the antigens were quantified by a solid phase radioimmunoassay using [125I]protein A to measure antibody binding. In mature pollen, these antigens were located in the cytoplasm and in the complex wall. In developing grains early in the maturation period, specific fluorescence was concentrated at the periphery of the cytoplasm.

Allergens↗
PubMed1980

Rapid batch fractionation of ryegrass pollen allergens.

A rapid batch fractionation procedure employing ion-exchange matrices has been used to fractionate ryegrass pollen antigens and allergens. After sequential elution through CM-Sephadex and DEAE-Sephadex, a group of four electrophoretically distinct allergens with a molecular weight of approximately 32,000 was fractionated. These allergens correspond to the group I allergens previously isolated by Johnson and Marsh. This material may be suitable for clinical use where a characterised group I allergen preparation is required.

Allergens↗
PubMed1980

Characteristics of pollen diffusates and pollen wall cytochemistry in poplars.

Pollen diffusates, known to be important in pollen-stigma interactions controlling interspecific incompatibility between Populus deltoides and Populus alba, have been partly characterized and shown to contain more than 20 protein bands by polyacrylamide gel electrophoresis, at least 4 of these being glycoproteins. Seven fractions had antigenic activity in rabbits and several enzyme activities were also present. Peroxidase and leucine aminopeptidase isoenzymes were detected in the diffusates, demonstrating the extracellular location of these 2 enzymes. Isoenzyme patterns of peroxidase, esterase and acid phosphatase were complex, with some bands common to both species. Localization of acid phosphatase in the intine and esterase in the exine was demonstrated after brief aldehyde fixation and low-temperature embedding in glycol methacrylate. The intine and exine sites were distinguished by their chemical and structural features. Calcofluor white M2R new proved to be an excellent stain for differentiating the intine. Aniline blue-positive material, probably beta-1,3-glucan, is present associated with the intine of many ungerminated as well as germinating grains: production of this material may be a response to damage.

Antigens↗
PubMed1979

Childhood asthma and grass pollen aerobiology in Melbourne.

Children from the Melbourne metropolitan area with laboratory proven bronchial sensitivity to ryegrass pollen were selected for a clinical trial which was run concurrently with an aerobiological survey during the grass pollen season of 1975 to 1976. During periods of high pollen counts, significant deterioration in the children's asthma occurred. The grass pollen season was of 10 weeks' duration with the highest daily counts during November and December. Highest diurnal pollen concentrations occurred at night and were associated with winds from the north, north-west, and south-east and with other meteorological factors.

Adolescent↗
PubMed1979

Pollen-stigma interactions: Identification and characterization of surface components with recognition potential.

Male-female recognition in flowering plants is initiated by mutual contact of pollen and stigma surface components. Analysis of the surface macromolecules of both stigma and pollen of Gladiolus gandavensis revealed a complex mixture of proteins, glycoproteins, and glycolipids. The carbohydrate-containing components amounted to 6% in pollen and 23% in stigma and contained the monosaccharides galactose, arabinose, glucose, mannose, and rhamnose. All the mannose of both preparations was associated with a fraction that bound to concanavalin A. The stigma surface contained an arabinogalactan or arabinogalactan protein as a major component. This component has been isolated by affinity chromatography on tridacnin-Sepharose and shown to be similar in composition to a style canal component isolated in the same way. The capacity of the stigma surface preparations to bind nonspecifically to macromolecules from pollen and other sources has been demonstrated in vivo and in vitro. Specific binding of concanavalin A to the stigma surface decreases the adhesive capacity for pollen protein. The arabinogalactan of the stigma surface may act as an adhesive base. The pollen and stigma surfaces apparently complement one another to provide all the components of an ideal adhesive.

Journal Article↗
PubMed1977

Immunofluorescent localization of urease in the cotyledons of jack bean, Canavalia ensiformis.

Urease has been localized in sections of cotyledons from germinating seeds of jack bean, using FITC-labelled immunoglobulin prepared from urease antiserum raised in rabbits. The complication of lectin binding to the immunoglobulins was resolved by treatment of the sections with specific glycosides. Urease is localized in 2 sites: within the cytoplasm of storage parenchyma cells in spherical granules up to 3 micrometer in diameter, and within the intercellular spaces in spherical granules. Although similar in size, the latter are distinguished from the cytoplasmic granules by the presence of beta-lectin and appear to function as an extracellular lytic compartment or lysosome.

Antibody Specificity↗
PubMed1976

Cell recognition in plants: Determinants of the stigma surface and their pollen interactions.

The interaction between compatible pollen grains and the female stigma of Gladiolus gandavensis has been used as a model system for investigation of cell recognition in plants. The molecular architecture of the receptive stigma surface has been investigated, and determinants binding to both concanavalin A and beta-glucosyl artificial carbohydrate antigen, as well as esterase activity, have been characterized, and conditions for their isolation have been established. The stigma surface, before and after modification, was found to bind (125)I-labeled proteins nonspecifically. Pollen tube penetration of the papillar cuticle is prevented when the receptor sites for concanavalin A are occupied. The concanavalin-A-binding determinants of the stigma surface have been fractionated to reveal several glycoproteins in the molecular weight range 43,000-93,000 and a group of glycolipids of molecular weight approximately 22,000. These results are interpreted in terms of two major recognition events regulating pollination.

Journal Article↗
PubMed1976

Pollen-wall proteins: quantitative cytochemistry of the origins of intine and exine enzymes in Brassica oleracea.

Simultaneous coupling methods for detection of acid phosphatase and non-specific esterase produce a coloured reaction product that is quantitatively related to enzyme content in freeze-sectioned Brassica pollen and tapetal cells. The intine-located acid phosphatase has 2 periods of synthesis: the first in late vacuolate period, associated with the completion of deposition of the intine polysaccharides; the second during pollen maturation, apparently reflecting cytoplasmic synthesis, Esterase activity accumulates in the tapetal cells until dissolution at early maturation period, when there is a dramatic rise in pollen-wall esterase activity, reflecting the transfer from tapetum to exine cavities. These quantitative studies confirm the gametophytic and sporophytic origins of the intine and exine proteins.

Acid Phosphatase↗
PubMed1975

Localization of lectins in legume cotyledons.

High-resolution techniques for the localization of lectins are described. Concanavalin A (Con A) and phytohaemagglutinin (PHA) are localized using a fluorescent method with (FITC)-labelled immunoglobulins which bind to the lectins in sections of jack and red kidney bean cotyledons. Specificity is defined by the use of specific sugar inhibitors. Both Con A and PHA are found in cytoplasmic sites. Lectins with beta-glycoside specificity are detected with red-coloured artificial carbohydrate antigens. The beta-galactosyl and beta-glucosyl antigens bind specifically to clusters of spherical bodies in the intercellular spaces, to cell wall sites, and to the periphery of the cytoplasm associated with the cell membrane.

Cell Wall↗