摘要 :
Grass pollens are amongst the most important aeroallergen sources world-wide triggering allergic rhinoconjunctivitis and asthma in sensitised patients. Much of what we know about the allergen components of grasses is informed by r...
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Grass pollens are amongst the most important aeroallergen sources world-wide triggering allergic rhinoconjunctivitis and asthma in sensitised patients. Much of what we know about the allergen components of grasses is informed by research on pollen of temperate (Pooideae) species that are abundant in the temperate climate zones. However, climate changes are altering the biogeographical distribution as well as timing and allergenicity of grass pollens. This provides an impetus for better understanding of the contribution of subtropical subfamilies of grasses to pollen allergy globally. Pollen of Chloridoideae (e.g. Cynodon dactylon; Bermuda grass) and Panicoideae (e.g. Paspalum notatum; Bahia grass or Sorghum halepense; Johnson grass) subfamilies are clinically important in subtropical zones of Australia, Asia, India, Africa, and America. These grasses differ ecologically and phylogenetically from temperate grasses and, importantly their allergen composition is qualitatively different. For example, subtropical grass pollens appear to lack the major group 5 grass pollen allergen family. In this review we summarize current knowledge of the epidemiology and immunology of subtropical Chloridoideae and Pancoideae pollen allergens, describe the biochemical characteristics of known isoforms and variants as well as properties and structures of subtropical pollen allergen components. Whilst only one subtropical allergen component; Cyn d 1 of Bermuda grass pollen, is available commercially for diagnostic use, in a natural purified form, a number of allergens of Panicoideae grass pollen; Zea m 1, Zea m 3 and Zea m 13 of maize, Pas n 1 and Pas n 13 of Bahia, as well as Sor h 1, Sor h 2, Sor h 13 and Sor h 23 of Johnson grass, have been discovered. Research effort is directed towards making available subtropical grass pollen allergen components as innovative treatment and diagnostic options that more specifically address the needs of patients from warmer regions of the globe.
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摘要 :
Plants of the genus Cynodon were considered as weed for a long period. However, this scenario has changed when it was observed that many species could be used in forage farming and for the recovery of degraded areas. Due to the hi...
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Plants of the genus Cynodon were considered as weed for a long period. However, this scenario has changed when it was observed that many species could be used in forage farming and for the recovery of degraded areas. Due to the high expansive potential, Cynodon spp. became an option for producers and aroused interest for breeding programs, besides requiring further studies on genetic and cytogenetic variability. Research onmeiosis in Cynodon are scarce since the inflorescences are small and the standardization of the stages of spikelet collections is difficult. The aim of the present study was to evaluate the microsporogenesis, viability and morphology of the pollen grains of two accessions of Cynodon dactylon var. dactylon (L.) Pers. (2n = 4x = 36, bermudagrass) and two accessions of Cynodon nlemfuensis var. nlemfuensis Vanderyst (2n = 2x = 18, stargrass). The slides were prepared by squash technique and stained with 2% carmine propionic. For the viability analyses of pollen grains, 2% propionic carmine and Alexander's stain were used. The measurements and the morphology of the pollen grains were defined from analyses with the acetolysis technique and scanning electron microscopy. The meiosis of the four accessions/species was regular. The staining tests showed variations in the viability rate of the pollen grain between the diploid and tetraploid species, being higher among the tetraploids. The pollen grains measured 21.1 and 28.8 mu m on average for both species and were classified as oblate spheroidal, monocolpates and showed no ornamentation, such as spicules and other attachments with non-roughened, micro reticulated exine. (c) 2018 SAAB. Published by Elsevier B.V. All rights reserved.
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Using differential screening we isolated a pistil-specific cDNA clone corresponding to a 1.2 kb mRNA and encoding a 32.5 kDa protein. The amino acid sequence shared similarity with that of group-I grass pollen allergens, which are...
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Using differential screening we isolated a pistil-specific cDNA clone corresponding to a 1.2 kb mRNA and encoding a 32.5 kDa protein. The amino acid sequence shared similarity with that of group-I grass pollen allergens, which are known to have expansin activity. This clone, which later showed to share homology also with beta-expansins, was named PPAL. The PPAL mRNA was specifically expressed in the secretory zone of the stigma and in the epidermal layer of the placenta. The accumulation level of the transcript increased during pollination, and the protein was secreted in the stigmatic exudate of the tobacco flower. We suggest here that PPAL is a new expansin, acting as a cell-wall-loosening agent during pollination.
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Bermuda grass pollen (BGP) contains a very complex mixture of allergens, but only a few have been characterized. One of the allergens, with an apparent molecular mass of 21 kDa, has been shown to bind serum IgE from 29% of patient...
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Bermuda grass pollen (BGP) contains a very complex mixture of allergens, but only a few have been characterized. One of the allergens, with an apparent molecular mass of 21 kDa, has been shown to bind serum IgE from 29% of patients with BGP allergy. A combination of chromatographic techniques (ion exchange and reverse phase HPLC) was used to purify the 21 kDa allergen. Immunoblotting was performed to investigate its IgE binding and lectin-binding activities, and the Lysyl-C endopeptidase digested peptides were determined by N-terminal sequencing. The cDNA sequence was analyzed by RACE PCR-based cloning. The protein mass and the putative glycan structure were further elucidated using MALDI-TOF mass spectrometry. The purified 21 kDa allergen was designated Cyn d 24 according to the protocol of International Union of Immunological Societies (IUIS). It has a molecular mass of 18 411 Da by MALDI-TOF analysis and a pI of 5.9. The cDNA encoding Cyn d 24 was predicted to produce a 153 amino acid mature protein containing tow conserved sequences seen in the pathogen-related protein family. Carbohydrate analysis showed that the most abundant N-linked glycan is a alpha(3)-fucosylated pauci-mannose (Man(3)GlcNAc(2)) structure, without a Xyl beta-(1,2)-linked to the branching beta-Man. Thus, Cyn d 24 is a glycoprotein and the results of the sequence alignment indicate that this novel allergen is a pathogenesis-related protein 1. To the best of our knowledge, this is the first study to identify any grass pollen allergen as a pathogenesis-related protein 1.
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