scholarly journals Pollen-Wall Proteins: Release of the Allergen Antigen E From intine and Exine Sites in Pollen Grains of Ragweed and Cosmos

1973 ◽  
Vol 13 (2) ◽  
pp. 603-619
Author(s):  
B. J. HOWLETT ◽  
R. B. KNOX ◽  
J. HESLOP-HARRISON
Keyword(s):  
Aqueous Media ◽  
Pollen Grains ◽  
Pollen Wall ◽  
Cytochemical Staining ◽  
Cosmos Bipinnatus ◽  
Associated Proteins ◽  
Staining Methods ◽  
Mobile Protein

Cytochemical staining methods and immunofluorescence techniques have been used to follow the release of proteins, including the allergen Antigen E, from whole pollen of ragweeds (Ambrosia spp.) and Cosmos bipinnatus (Compositae). These proteins have been detected in 2 sites in the wall: in the inner cellulosic intine layer especially at the germinal apertures, and in the cavea and the cavities of the outer exine layer, the sexine. It was found that the release of exine-associated proteins, including the allergenic fraction, begins within 2 s of contact with aqueous media, the loss being mainly through the micropores of the tectum at the bases of the sexine spines. The intine proteins were emitted more slowly, discharge beginning at the colpi after 1 min of moistening. So far as can be judged from the methods used, most of the mobile protein lost from the pollen of Cosmos on hydration comes from the exine and is therefore sporophytic in origin, while in the ragweeds the bulk comes from the intine in the neighbourhood of the germinal apertures, and so is gametophytic.

Pollen-Wall Proteins: Localization and Enzymic Activity

1970 ◽  
Vol 6 (1) ◽  
pp. 1-27
Author(s):  
R. B. KNOX ◽  
J. HESLOP-HARRISON
Keyword(s):  
Enzyme Activity ◽  
Pollen Tube ◽  
Early Period ◽  
Pollen Grains ◽  
Spore Wall ◽  
Enzymic Activity ◽  
Developmental Study ◽  
Cosmos Bipinnatus ◽  
Pollen Types ◽  
Staining Methods

Cytochemical methods have been used to examine the distribution of acid phosphatase, ribonuclease, esterase, amylase and protease activity and protein in the walls of pollen grains and spores. Enzyme activity was detected in the walls of 50 angiosperm pollens, in pine, and in the spore wall of a species of Equisetum. Activity was absent from the 2 species of ferns examined. The survey covered all major structural pollen types. In all cases enzyme activity was associated principally with the intine, the inner cellulosic part of the wall. In all aperturate grains activity was concentrated in or around the apertural intine; that is, over or near the potential sites of emergence of the pollen tube. Protein concentrations in the intine at these sites could be demonstrated in several pollen types by staining methods and by absorption at 285 nm. Developmental study showed that the enzymes are incorporated in the intine during the early period of wall growth following the release of the spores from the melotic tetrads. During this period, stratified ribosomal endoplasmic reticulum lies adjacent to the inner spore wall over the areas of incorporation. In Cosmos bipinnatus, a composite, the material is incorporated as ribbons or leaflets, which interleave with cellulose lamellae. In other species the wall protein may take the form of granules, tubules or vesicles, embedded in the intine cellulose. At maturity the intine is separated from the spore cytoplasm by an intact plasmalemma, so the wall enzymes are to be regarded as being extracellular. In some species enzyme activity was detected in materials on the surface of the pollen exine derived probably from the surrounding tapetal tissue; however, this was usually insignificant compared with that shown by the intine. The intine enzymes are very readily leachable, and their function is probably connected with the early nutrition of the pollen tube and the penetration of the stigma. It is likely that the wall proteins make up a very large proportion of mobile protein of the pollen grain, and they may therefore be important in pollen allergenicity.

Pollen Wall Proteins: Pollen-Stigma Interactions in Ragweed and Cosmos (Compositae)

1973 ◽  
Vol 12 (2) ◽  
pp. 421-443 ◽  
Author(s):  
R. B. KNOX
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Pollen Grains ◽  
Pollen Tubes ◽  
Pollen Wall ◽  
Stigma Surface ◽  
Cosmos Bipinnatus ◽  
Stigmatic Papillae ◽  
Scanning Electron

The release of wall-held materials from the pollen of ragweed (Ambrosia tenuifolia) and Cosmos bipinnatus on to the stigma surface has been followed. When fresh stigmas were viewed by scanning electron microscopy, a fluid material was observed coating pollen grains, pollen tubes and adjacent stigmatic papillae. This fluid contained pollen-wall antigens, including the allergen Antigen E, detected by immunofluorescence, and proteins, lipids and carbohydrates detected by cytochemical methods. In Cosmos, the fate of the antigens was much the same after both compatible and incompatible matings. In incompatible matings, pollen tubes were blocked with a polysaccharide considered to be callose. Callose particles appeared on neighbouring stigmatic papillae, and adjacent stigmatic hairs accumulated callose internally. This reaction may be an important one for the incompatibility response.

FIB-SEM: An Additional Technique for Investigating Internal Structure of Pollen Walls

2013 ◽  
Vol 19 (6) ◽  
pp. 1535-1541 ◽  
Author(s):  
Alisoun House ◽  
Kevin Balkwill
Keyword(s):  
Electron Microscopy ◽  
Internal Structure ◽  
Focused Ion Beam ◽  
Ion Beam ◽  
Three Dimensional ◽  
Pollen Grains ◽  
Grain Morphology ◽  
Pollen Grain ◽  
Pollen Wall ◽  
Scanning Electron

AbstractPollen grain morphology has been widely used in the classification of the Acanthaceae, where external pollen wall features have proved useful in determining relationships between taxa. Although detailed information has been accumulated using light microscopy, transmission electron microscopy and scanning electron microscopy (SEM) techniques, internal pollen wall features lack investigation and the techniques are cumbersome. A new technique involving precise cross sectioning or slicing of pollen grains at a selected position for examining wall ultrastructure, using a focused ion beam-scanning electron microscope (FIB-SEM), has been explored and promising results have been obtained. The FIB-SEM offers a good technique for reliable, high resolution, three-dimensional (3D) viewing of the internal structure of the pollen grain wall.

Development of sperm cells in barley

1975 ◽  
Vol 53 (10) ◽  
pp. 1051-1062 ◽  
Author(s):  
David D. Cass ◽  
Ilana Karas
Keyword(s):  
Cell Membrane ◽  
Vegetative Cell ◽  
Generative Cell ◽  
Pollen Grains ◽  
Complete Separation ◽  
Pollen Wall ◽  
Vegetative Nucleus ◽  
Sperm Cells ◽  
Subsequent Stage ◽  
Microspore Stage

Ultrastructural events in barley sperm development were examined from the uninucleate microspore stage to establishment of two mature sperm cells in pollen grains. Microspore mitosis produces a vegetative nucleus and a naked generative cell, both embedded in vegetative cell cytoplasm. The generative cell membrane is enclosed by vegetative cell membrane. The generative cell, at first apparently unattached, becomes attached to the pollen wall and acquires a cell wall by centripetal vesicle accumulation. Wall formation may be complete at the time of generative cell karyokinesis; karyokinesis occurs while the generative cell is attached to the pollen wall. Cytokinesis of the generative cell is delayed. The subsequent stage is a binucleate, attached generative cell with a wall. Generative cell cytokinesis appears to involve formation of a partition between the two sperm nuclei. Eventual complete separation of the sperm cells occurs only after the two-celled derivative of the generative cell detaches from the pollen wall. Final stages in sperm cell separation are considered to result from degradation of the partitioning and surrounding wall, not from furrowing of a naked binucleate generative cell according to previous suggestions. Mature plastids were not observed in the generative cell or the sperms.

Development of wheat (Triticum aestivum) pollen wall before and after effect of a gametocide

1990 ◽  
Vol 68 (11) ◽  
pp. 2509-2516 ◽  
Author(s):  
Gamal A. El-Ghazaly ◽  
William A. Jensen
Keyword(s):  
Electron Microscopy ◽  
Triticum Aestivum ◽  
Key Words ◽  
Light And Electron Microscopy ◽  
Pollen Grains ◽  
Pollen Wall ◽  
Seed Plants ◽  
Before And After ◽  
After Effect

Light and electron microscopy studies show that pollen wall development in plants treated with the gametocide RH0007 and untreated plants was similar until the stage at which sporopollenin is normally deposited on the wall. At this stage, the pollen wall of treated plants is 80% thinner than that of the control. Shortly after this stage, the pollen grains in the treated plants collapse and abort. We conclude that the gametocide clearly acts through the inhibition of sporopollenin formation, which results in pollen death. As sporopollenin is found only in the pollen wall of seed plants and the spores of nonseed plants, harm to other parts of the plant is not expected to occur. Key words: pollen wall development, Triticum aestivum, gametocide.

Magnetic pollen grains as sorbents for facile removal of organic pollutants in aqueous media

2011 ◽  
Vol 194 ◽  
pp. 53-61 ◽  
Author(s):  
Beng Joo Reginald Thio ◽  
Kristin K. Clark ◽  
Arturo A. Keller
Keyword(s):  
Organic Pollutants ◽  
Aqueous Media ◽  
Pollen Grains

The Croonian Lecture, 1974 - The physiology of the pollen grain surface

1975 ◽  
Vol 190 (1100) ◽  
pp. 275-299 ◽  
Keyword(s):  
Hydrolytic Enzymes ◽  
Structural Complexity ◽  
Pollen Grains ◽  
Pollen Wall ◽  
Early Application ◽  
Growth And Nutrition ◽  
Pollen Surface ◽  
Pollen Vectors ◽  
Angiosperm Pollen ◽  
Grain Surface

Angiosperm pollen grains possess walls of remarkable structural complexity, and the architectural forms encountered are often sufficiently specific and consistent to be useful taxonomically. Lindley, von Mohl and others appreciated this systematic potential almost a century and a half ago, and today a comprehensive pollen taxonomy is taking shape with the publication of the World pollen flora founded by the late Professor Gunnar Erdtman. Surprisingly, until quite recently this interest in the taxonomic aspects of pollen wall morphology has not been matched by any great concern for the functional significance of even the most conspicuous features, such for example as the deep sculpturing so commonly found in the outer layer of the wall. When Erdtman spent a period in my laboratory in Belfast in the mid-1950s we talked at length about pollen and spore morphology and morphogenesis, but I do not recall that we seriously touched upon the adaptive meaning of the wall architecture. We need not have heen so blind, for there were already many suggestive leads. Wodehouse in his distinguished book of 1935 addressed himself not only to the problems of pollen wall morphogenesis, but noted also relations between structure and dispersal agency. German authors had thought along similar lines, and had already pointed to the functional importance of one type of pollen surface material, that which in some species acts as a binding agent ( Polenkitt ), holding grains together in groups and facilitating attachment to pollen vectors. Much earlier had appeared the work of Green (1894), who seems to have been the first to study the nature of pollen emissions. In an early application of substrate film methods, Green showed that intact moistened pollen grains released various hydrolytic enzymes, and surmised that these played some part in the pollen-stigma interaction, perhaps in germination and pollen-tube growth and nutrition. When Green wrote, Blackley’s famous work on the causes of hay fever was already 20 years old; and by the 1950s it was well established that the active constituents released by pollen were non-dialysable and predominantly protein in nature. Various authors commented on the rapidity with which protein exudates are released from pollen grains, and there was speculation on the sources of such mobile fractions; indeed the facts suggested the possibility that these, too, were held like Pollenkitt in sites at or near the surface.

Sign in / Sign up

Export Citation Format

Share Document