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Immunology and Allergy Clinics of North... Feb 2021Pollens are a major cause of seasonal allergic diseases. Weather may alter the production of pollens. Increased atmospheric temperatures lead to earlier pollination of... (Review)
Review
Pollens are a major cause of seasonal allergic diseases. Weather may alter the production of pollens. Increased atmospheric temperatures lead to earlier pollination of many plants and longer duration of pollination, resulting in extended pollen seasons, with early spring or late winter. Longer pollen seasons increase duration of exposure, resulting in more sensitization, and higher pollen concentrations may lead to more severe symptoms. Climate changes in contact to pollens may affect both allergic sensitization and symptom prevalence with severity. The future consequences of climate change, however, are speculative, because the influence on humans, is complex.
Topics: Allergens; Climate Change; Humans; Hypersensitivity; Pollen; Seasons
PubMed: 33228876
DOI: 10.1016/j.iac.2020.09.004 -
Plant, Cell & Environment Mar 2021Research concerning the effects of ionizing radiation (IR) on plant systems is essential for numerous aspects of human society, as for instance, in terms of agriculture... (Comparative Study)
Comparative Study Review
Research concerning the effects of ionizing radiation (IR) on plant systems is essential for numerous aspects of human society, as for instance, in terms of agriculture and plant breeding, but additionally for elucidating consequences of radioactive contamination of the ecosphere. This comprehensive survey analyses effects of x- and γ-irradiation on male gametophytes comprising primarily in vitro but also in vivo data of diverse plant species. The IR-dose range for pollen performance was compiled and 50% inhibition doses (ID ) for germination and tube growth were comparatively related to physiological characteristics of the microgametophyte. Factors influencing IR-susceptibility of mature pollen and polarized tube growth were evaluated, such as dose-rate, environmental conditions, or species-related variations. In addition, all available reports suggesting bio-positive IR-effects particularly on pollen performance were examined. Most importantly, for the first time influences of IR specifically on diverse phylogenetic models of polar cell growth were comparatively analysed, and thus demonstrated that the gametophytic system of pollen is extremely resistant to IR, more than plant sporophytes and especially much more than comparable animal cells. Beyond that, this study develops hypotheses regarding a molecular basis for the extreme IR-resistance of the plant microgametophyte and highlights its unique rank among organismal systems.
Topics: Cell Polarity; Dose-Response Relationship, Radiation; Germination; Models, Biological; Pollen; Pollen Tube; Radiation, Ionizing
PubMed: 33124689
DOI: 10.1111/pce.13929 -
Nature Communications Mar 2020Pollen's practically-indestructible shell structure has long inspired the biomimetic design of organic materials. However, there is limited understanding of how the...
Pollen's practically-indestructible shell structure has long inspired the biomimetic design of organic materials. However, there is limited understanding of how the mechanical, chemical, and adhesion properties of pollen are biologically controlled and whether strategies can be devised to manipulate pollen beyond natural performance limits. Here, we report a facile approach to transform pollen grains into soft microgel by remodeling pollen shells. Marked alterations to the pollen substructures led to environmental stimuli responsiveness, which reveal how the interplay of substructure-specific material properties dictates microgel swelling behavior. Our investigation of pollen grains from across the plant kingdom further showed that microgel formation occurs with tested pollen species from eudicot plants. Collectively, our experimental and computational results offer fundamental insights into how tuning pollen structure can cause dramatic alterations to material properties, and inspire future investigation into understanding how the material science of pollen might influence plant reproductive success.
Topics: Biomimetics; Computational Chemistry; Epitopes; Esterification; Hardness; Hydrolysis; Hydroxides; Materials Science; Microgels; Microscopy, Fluorescence; Pectins; Pollen; Pollination; Potassium Compounds; Spectroscopy, Fourier Transform Infrared
PubMed: 32193375
DOI: 10.1038/s41467-020-15294-w -
Environmental Pollution (Barking, Essex... Aug 2023Ozone exacerbates allergy symptoms to certain pollens. The molecular mechanisms by which ozone affects pollen grains (PGs) and allergies are not fully understood,...
Ozone exacerbates allergy symptoms to certain pollens. The molecular mechanisms by which ozone affects pollen grains (PGs) and allergies are not fully understood, especially as the effects of pollutants may vary depending on the type of pollen. In this work, pollens of 22 different taxa were exposed under laboratory conditions to ozone (100 ppb) to quantify the ozone uptake by the PGs. The ozone uptake was highly variable among the 22 taxa tested. The highest ozone uptake per PG was measured on Acer negundo PGs (2.5 ± 0.2 pg∙PG). On average, tree pollens captured significantly more ozone than herbaceous pollens (average values of 0.5 and 0.02 pg∙PG, respectively). No single parameter (such as the number of apertures, pollen season, pollen size, or lipid fraction) could predict a pollen's ability to take up ozone. Lipids seem to act as a barrier to ozone uptake and play a protective role for some taxa. After inhalation of PGs, pollen-transported ozone could be transferred to mucous membranes and exacerbate symptoms through oxidative stress and local inflammation. Although the amount of ozone transported is small in absolute terms, it is significant compared to the antioxidant capacity of nasal mucus at a microscale. This mechanism of pollen-induced oxidative stress could explain the aggravation of allergic symptoms during ozone pollution episodes.
Topics: Allergens; Ozone; Pollen; Hypersensitivity; Environmental Pollutants
PubMed: 37196838
DOI: 10.1016/j.envpol.2023.121793 -
Protoplasma Aug 2006Pollen accumulates starch reserves during development and the final stage of ripening. Before the anther opens, starch is totally or partially converted to pectins,... (Review)
Review
Pollen accumulates starch reserves during development and the final stage of ripening. Before the anther opens, starch is totally or partially converted to pectins, glucose, fructose, sucrose, and to some unknown polysaccharides. Pollen is exposed to dispersing agents in an arrested developmental state which differs according to pollen water content. Pollen is classified as partially dehydrated or partially hydrated. The final water content may be reached before or after anther opening. Especially during exposure and dispersal, partially dehydrated pollen may interconvert soluble and insoluble reserves, modifying internal turgor pressure and hindering water loss or gain. Partially hydrated pollen is commonly devoid of mechanisms to conserve viability in time but has the advantage of quickly emitting pollen tubes on reaching the stigma.
Topics: Carbohydrates; Cell Survival; Desiccation; Pollen; Water
PubMed: 16937057
DOI: 10.1007/s00709-006-0169-z -
The Plant Cell Aug 1992
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Gaceta Medica de Mexico 2009Allergic respiratory diseases such asthma and allergic rhinitis are a health problem throughout the world. In Mexico City, pollens are an important cause of allergic... (Review)
Review
Allergic respiratory diseases such asthma and allergic rhinitis are a health problem throughout the world. In Mexico City, pollens are an important cause of allergic respiratory disease. Both, the geographic location- and the vegetation surrounding this City favor the distribution of pollens leading to respiratory disease in susceptible patients. Aerobiological studies have shown that during the mild dry winter there is a large amount of pollens in the environment with tree pollens being the most abundant of all. The most frequent tree pollens found in Mexico City include Fraxinus, Cupressaseae, Alnus, Liquidambar, Callistemon, Pinus, and Casuarina. In contrast, grass- and weed pollens predominate during the summer (rainy season) including Compositae, Cheno-Am, Ambrosia and Gramineae. An additional health problem in Mexico City is the air pollution that exerts a direct effect on individuals. This in turn increases pollen allergenicity by disrupting them leading to the release of their particles which then penetrate the human airways causing disease. Thus, the polluted environment along with global warming which is also known to increase pollen quantities by inducing longer pollen seasons may represent a health risk to Mexico City inhabitants.
Topics: Environment; Humans; Pollen; Respiratory Hypersensitivity
PubMed: 19685827
DOI: No ID Found -
American Journal of Botany May 2019Optimal defense theory predicts that selection should drive plants to disproportionally allocate resources for herbivore defense to tissues with high fitness values....
PREMISE
Optimal defense theory predicts that selection should drive plants to disproportionally allocate resources for herbivore defense to tissues with high fitness values. Because pollen's primary role is the transport of gametes, plants may be expected to defend it from herbivory. However, for many animal-pollinated plants, pollen serves a secondary role as a pollinator reward. These dual roles may present a conflict between selection to defend pollen from herbivores and selection to reward pollinators. Here, we investigate whether pollen secondary chemistry in three pollen-rewarding Lupinus species better reflects the need to defend pollen or reward pollinators.
METHODS
Lupinus (Fabaceae) species are nectarless, pollen-rewarding, and produce defensive quinolizidine and/or piperidine alkaloids throughout their tissues. We used gas chromatography to identify and quantitate the alkaloids in four aboveground tissues (pollen, flower, leaf, stem) of three western North American lupines, L. argenteus, L. bakeri, and L. sulphureus, and compared alkaloid concentrations and composition among tissues within individuals.
RESULTS
In L. argenteus and L. sulphureus, pollen alkaloid concentrations were 11-35% of those found in other tissues. We detected no alkaloids in L. bakeri pollen, though they were present in other tissues. Alkaloid concentrations were not strongly correlated among tissues within individuals. We detected fewer alkaloids in pollen compared to other tissues, and pollen contained no unique alkaloids.
CONCLUSIONS
Our results are consistent with the hypothesis that, in these pollen-rewarding species, pollen secondary chemistry may reflect the need to attract and reward pollinators more than the need to defend pollen from herbivory.
Topics: Alkaloids; Chromatography, Gas; Flowers; Lupinus; Plant Leaves; Plant Stems; Pollen; Pollination
PubMed: 31046151
DOI: 10.1002/ajb2.1283 -
Asian Pacific Journal of Allergy and... Dec 2013Over the past few decades, there has been an explosion of understanding of the molecular nature of major allergens contained within pollens from the most important... (Review)
Review
Over the past few decades, there has been an explosion of understanding of the molecular nature of major allergens contained within pollens from the most important allergenic plant species. Most major allergens belong to only a few protein families. Protein characteristics, cross-reactivity, structures, and IgE binding epitopes have been determined for several allergens. These efforts have led to significant improvements in specific immunotherapy, yet there has been little discussion about the physiological functions of these proteins. Even with large amounts of available information about allergenic proteins from pollens, the incidence of pollen allergy continuously increases worldwide. The reason for this increase is unclear and is most likely due to a combination of factors. One important culprit might be a change in the pollen itself. Knowledge about pollen biology and how pollen is changing as a result of more extreme environmental conditions might improve our understanding of the disease. This review focuses on the characteristics of plants producing allergenic pollens that are relevant to pollen allergy, including the phylogenetic relationships, pollen dispersal distances, amounts of pollen produced, amounts of protein in each type of pollen, and how allergenic proteins are released from pollens. In addition, the physiological roles of major allergenic protein families will be discussed to help us understand why some of these proteins become allergens and why GMO plants with hypoallergenic pollens may not be successful.
Topics: Allergens; Humans; Plant Proteins; Pollen; Pollination; Rhinitis, Allergic, Seasonal; Wind
PubMed: 24383968
DOI: No ID Found -
The Journal of Allergy and Clinical... Jun 2002The transfer of pollen, whether it is transported by insects or carried by the wind, from floral anther to recipient stigma is the critical reproductive event among... (Review)
Review
The transfer of pollen, whether it is transported by insects or carried by the wind, from floral anther to recipient stigma is the critical reproductive event among higher plants. In this scenario, the pollen grain functions as a fully constituted life-cycle stage, capable of growth (albeit limited) and delivery of gametes. Pollen is prepared for this role by an intricate developmental process with dual sources of structural elements and chemical constituents, including allergens. The resulting complexity relates, at least in part, to the requirements of an unforgiving recognition process at stigmatic surfaces and of active growth before the achievement of gametic union. Recently, the basic participants in pollen-stigma interactions have been defined, and they provide a striking counterpoint to human histocompatibility concerns. Pollen development offers a useful tableau in terms of which to reexamine forces affecting pollen prevalence and their interactions. Development also provides clues to the sources and significance of more minute bioaerosols now known to carry pollen allergens.
Topics: Air Pollutants; Allergens; Environmental Monitoring; Humans; Pollen
PubMed: 12063515
DOI: 10.1067/mai.2002.125556