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Pest Management Science, Vol. 58, No. 4. (2002), pp. 374-380.Houseflies (Musca domestica L) accumulated electrostatic charges when walking over clean, uncharged dielectric surfaces. The charges elicited on a walking housefly by a range of materials were quantified, allowing a triboelectric series to be determined relative to M domestica. This ranged from surfaces that charged individuals positively, eg Correx (corrugated polypropylene) , to those that applied a negative charge, eg clear cast acrylic . Maximum positive and negative charges accumulated by individual M domestica were +73 and -27 pC. Replicate measurements on the same fly and surface showed little variation. Variation between individuals was not related to sex and was not consistent between surfaces. Different materials charged M domestica significantly differently and individual flies had significantly different charging properties. Variation in temperature between 21.3 °C and 24.7 °C and humidity between 24% and 41% RH significantly affected charge accumulated by M domestica on some surfaces, although further experimentation is needed to confirm this. The implications of this work are discussed in relation to insect trap design and pollination biology.© 2002 Society of Chemical IndustryDaniel Mcgonigle, Chris Jackson, citeulike.org

Planta, Vol. 146, No. 2. (1 January 1979), pp. 211-216.Quantitative studies of the adhesion of pollen grains to the stigma in Brassica oleracea revealed that self-pollen is initially less firmly bound than cross-pollen. The pollen grain tryphine, believed to be important in the adhesion process, has been shown to differ in mobility following self- and cross-pollination when observed using fluorescent probes. The hydration of the pollen grains has been investigated in vitro by measuring the changes in shape, volume and fresh weight of the imbibing grains. Whilst little change in volume could be detected there was a considerable increase in fresh weight together with a change of shape. The significance of these events, which occur prior to pollen germination, is discussed in relation to their effect upon subsequent germination and expression of self-incompatibility.AD Stead, IN Roberts, HG Dickinson, citeulike.org

Symposia of the Society for Experimental Biology, Vol. 51 (1998), pp. 51-57.The pollen grain coating of Brassica oleracea contains a polymorphic family of highly charged small proteins (PCP-A, pollen coat protein, class A) related to the defensin class of seed proteins. On pollination these proteins are released from the grain and in vitro data suggest that at least one member of the family (PCP-A1) interacts specifically with elements of the stigmatically-expressed S(self-incompatibility) receptor complex. A new in vivo bioassay has demonstrated the male determinant of the self incompatibility system to be contained within the pollen coating, and this determinant to be a low molecular mass protein. A combination of data from interspecific studies and molecular analysis of PCP-A proteins indicates that the primary interaction between PCP-A1 and the receptor complex may be involved in establishing compatibility, while other molecular interactions, perhaps involving other PCP-A class proteins, are responsible for regulating S-specific rejection of self grains. The evolution of the self incompatibility system on the dry sigma of Brassica is discussed in the context of these data.HG Dickinson, J Doughty, SJ Hiscock, CJ Elleman, AG Stephenson, citeulike.org

Proceedings of the National Academy of Science, Vol. 73 (August 1976), pp. 2788-2792.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 125I-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.RB Knox, A Clarke, S Harrison, P Smith, JJ Marchalonis, citeulike.org

Proceedings of the National Academy of Sciences of the United States of America, Vol. 97, No. 7. (28 March 2000), pp. 3765-3770.Adhesion of pollen grains to the stigmatic surface is a critical step during sexual reproduction in plants. In Brassica, S locus-related glycoprotein 1 (SLR1), a stigma-specific protein belonging to the S gene family of proteins, has been shown to be involved in this step. However, the identity of the interacting counterpart in pollen and the molecular mechanism of this interaction have not been determined. Using an optical biosensor immobilized with S gene family proteins, we detected strong SLR1-binding activity in pollen coat extracts of Brassica campestris. Two SLR1-binding proteins, named SLR1-BP1 and SLR1-BP2, were identified and purified by the combination of SLR1 affinity column chromatography and reverse-phase HPLC. Sequence analyses revealed that these two proteins (i) differ only in that a proline residue near the N terminus is hydroxylated in SLR1-BP1 but not in SLR1-BP2, and (ii) are members of the class A pollen coat protein (PCP) family, which includes PCP-A1, an SLG (S locus glycoprotein)-binding protein isolated from Brassica oleracea. Kinetic analysis showed that SLR1-BP1 and SLR1-BP2 specifically bound SLR1 with high affinity (K(d) = 5.6 and 4.4 nM, respectively). The SLR1-BP gene was specifically expressed in pollen at late stages of development, and its sequence is highly conserved in Brassica species with the A genome.S Takayama, H Shiba, M Iwano, K Asano, M Hara, FS Che, M Watanabe, K Hinata, A Isogai, citeulike.org

Annual Review of Genetics, Vol. 38, No. 1. (2004), pp. 793-818.Abstract For pollination to succeed, pollen must carry sperm through a variety of different floral tissues to access the ovules within the pistil. The pistil provides everything the pollen requires for success in this endeavor including distinct guidance cues and essential nutrients that allow the pollen tube to traverse enormous distances along a complex path to the unfertilized ovule. Although the pistil is a great facilitator of pollen function, it can also be viewed as an elaborate barrier that shields ovules from access from inappropriate pollen, such as pollen from other species. Each discrete step taken by pollen tubes en route to the ovules is a potential barrier point to ovule access and waste by inappropriate mates. In this review, we survey the current molecular understanding of how pollination proceeds, and ask to what extent is each step important for mate discrimination. As this field progresses, this synthesis of functional biology and evolutionary studies will provide insight into the molecular basis of the species barriers that maintain the enormous diversity seen in flowering plants.Robert Swanson, Anna Edlund, Daphne Preuss, citeulike.org

Plant Systematics and Evolution, Vol. 181, No. 3. (1992), pp. 171-178.50% breaking point pressures of pollen grain walls of eleven species were determined. The breaking point pressures of most pollen grain walls are equivalent to those reported in the literature for other types of living cell walls such as bacterial spore coats, algal cell walls, mold sporophyte cells, and dicot suspension culture cells. The strongest pollen grain walls are two or three orders of magnitude stronger, however. Pollen grain walls are proportionately very thick in comparison to other types of cell walls. It is this thickness, not the construction or physical properties of the pollen grain wall, that most probably accounts for their strength.MR Bolick, S Vogel, citeulike.org

Plasma Science and Technology, Vol. 7, No. 6. (2005), pp. 3176-3180.The aim of this study is to investigate the biological effects of ion beams on pollen. Pollen grains of Cedrus deodara were implanted with 30 keV nitrogen ion beams at doses ranging from 1 × 1015 ions/cm2 to 15 × 1015 ions/cm2. The effects of N+ implantation on the pollen exine substructure were examined using an atomic force microscope (AFM), and the structure and morphology of pollen and pollen tubes were observed using a laser scanning confocal microscope (LSCM). AFM observations distinctly revealed the erosion of the pollen exine caused by N+ implantation in the micrometer to nanometer range. Typical results showed that the erosion degree was linearly proportional to the ion dose. Pollen germination experiments in vitro indicated that N+ implantation within a certain dose range increased the rate of pollen germination. The main abnormal phenomena in pollen tubes were also analyzed. Our results suggest that low energy ion implantation with suitable energy and dosage can be used to break the pollen wall to induce a transfer of exogenous DNA into the pollen without any damage to the cytoplasm and nuclei of the pollen. The present study suggests that a combination of the method of ion-beam-induced gene transfer and the pollen-tube pathway method (PTPW) would be a new plant transformation method.Li Guoping, Huang Qunce, Qin Guangyong, Huo Yuping, citeulike.org

The Plant Journal (December 1997), pp. 1351-1359.An in vitro bioassay has been developed to explore the role of the pollen coating in the pollen/stigma interaction in Brassica oleracea. In the assay, coating is removed from pollen grains, supplemented with protein fractions isolated from coatings of different S (self incompatibility) haplotypes, and then?using micromanipulation?interposed between individual pollen grains and the stigmatic surface. Normally, the coating used is of the same haplotype as the pollen in the experiment?thus constituting an `extension' of its own coat?but carrying the supplemented protein fractions. Initial experiments confirmed preliminary data that the pollen coating contained the male determinant of self incompatibility (SI); not only did the addition of `self' coating (i.e. that with the same S-haplotype as the stigma) prevent the success of a compatible cross pollination, but a `cross' coating (i.e. that with a different S-haplotype from the stigma) could induce the germination and growth of self pollen. Protein supplementation experiments demonstrated that the pollen-held determinant is contained within the water soluble component of the pollen coat, while further analysis revealed that the active molecular species possesses an Mr?10 kDa. More extensive fractionation by gel filtration and reverse phase HPLC was used to isolate a family of basic, cysteine-rich proteins (PCP-A: Pollen Coat Proteins-class A)?one of which is known to bind to stigmatically-expressed components of the S-locus in Brassica. Introduction of the PCP-A protein fraction into the bioassay confirmed the male determinant of SI as a protein, and probably a member of the PCP-A protein family.Andrew Stephenson, James Doughty, Suzanne Dixon, Carole Elleman, Simon Hiscock, Hugh Dickinson, citeulike.org

Plant Physiol., Vol. 115, No. 3. (1 November 1997), pp. 1221-1230.DT Luu, P Heizmann, C Dumas, citeulike.org