Pollen production, microsporangium dehiscence and pollen flow in Himalayan cedar (Cedrus deodara Roxb. ex d. Don).
(1/31)
Microsporangium dehiscence, pollen production and dispersal were studied in Himalayan cedar (Cedrus deodara) during 1998 and 1999. Microsporangium dehiscence showed diurnal periodicity and was found to be related to air temperature and relative air humidity, with a strobilus taking 2 d to dehisce completely in warmer conditions and 3 d in cooler ones. The frequency of flowering in C. deodara was highly variable during the two successive years; however, cyclical production of pollen grains was observed in 50% of the trees. The maximum concentration of pollen grains in the air was found between 1200 and 1600 h, and this period was also noted to be the best time for pollination. Studying migration of pollen grains from isolated single trees in three directions showed that migration was not uniform in all directions. Long-distance transport of pollen grains was observed in the downhill direction. However, in the uphill and horizontal directions grains could travel only up to 97.5 and l95.1 m, respectively, and the frequency of pollen grains to the source frequency at these distances was only 1.9 and 2-5%, respectively. The results suggest that an isolation barrier of 190 m may be considered as a minimum for the management of deodar seed orchards. (+info)
Reduction of antigenicity of Cry j I, major allergen of Japanese cedar pollen, by the attachment of polysaccharides.
(2/31)
An attempt was made to mask the allergenic structure of a major allergen protein, Cry j I (CJI), in Japanese cedar pollen using the Maillard-type polysaccharide conjugation. The SDS-PAGE pattern of the CJI-galactomannan conjugate prepared by the Maillard reaction showed broad bands widely distributed from 50 kDa to more than 100 kDa, suggesting the attachment of galactomannan. The competitive enzyme-linked immunosorbent assay showed that the IgE antibody in the sera of cedar pollen-sensitive patients reacted strongly with CJI, while it did not react with the CJI-galactomannan conjugate. This result suggests that the antigenicity of CJI is greatly reduced by the conjugation with galactomannan. (+info)
Fine-scale estimation of outcrossing in western redcedar with microsatellite assay of bulked DNA.
(3/31)
Western redcedar (Thuja plicata, Cupressaceae) is a self-fertile conifer with a mixed mating system and significant variation for outcrossing among populations. In this paper, we conducted a fine-scale study of mating system variation to identify correlates of outcrossing in natural populations. We examined variation for outcrossing within and among individual trees, and describe a new method to estimate outcrossing using bulked DNA samples. Bulking (assaying DNA tissues from several individuals simultaneously) increases the experimental power without increasing the experimental effort. We sampled 80 trees from four natural populations in southwestern British Columbia. From each tree, we sampled from up to six crown positions (three heights and inner vs outer branches). From each position, two samples of three seedlings each were bulked before DNA extractions. Using four microsatellite loci, we obtained outcrossing rates for each tree and for each of the six crown positions. We found individual tree selfing rates to increase with tree height in all four populations, but selfing rates did not differ among crown positions. The higher selfing rate of larger trees is probably due to their greater proportional contribution to local pollen clouds. Individual tree outcrossing rates ranged from 22 to 100% and the population outcrossing rates from 66 to 78%. Missed alleles due to bulking and the estimation method used both cause a downward bias in outcrossing rates, so that these estimates are probably lower than the actual outcrossing rates. Nevertheless, the trends we observed are not affected by systematic biases of estimation. (+info)
Impact of founder population, drift and selection on the genetic diversity of a recently translocated tree population.
(4/31)
Recently established, temperate tree populations combine a high level of differentiation for adaptive traits, suggesting rapid genetic evolution, with a high level of genetic diversity within population, suggesting a limited impact of genetic drift and purifying selection. To study experimentally the evolutionary forces in a recently established population, we assessed the spatial and temporal patterns of genetic diversity within a disjunct population of Cedrus atlantica established 140 years ago in south-eastern France from a North African source. The population is expanding through natural regeneration. Three generations were sampled, including founder trees. We analysed 12 isozyme loci, three of which were previously found in tight association with selected genes, and quantitative traits. No bottleneck effect was detected in the founder generation, but a simple test of allelic association revealed an initial disequilibrium which disappeared in the following generations. The impact of genetic drift during secondary evolution was limited, as suggested by the weak temporal differentiation. The genetic load was not reduced after 3 generations, and the quantitative variation for adaptive traits did not change either. Thus, initial genetic changes first proceed from a rapid re-organisation of the diversity through mating and recombination, whereas genetic erosion through drift and selection is delayed due to temporal and spatial stochasticity. Two life-history traits of trees contribute to slowing down the processes of genetic erosion: perenniality and large spatial scale. Thus, one would expect recently established tree populations to have a higher diversity than older ones, which seems in accordance with experimental surveys. (+info)
Clinical efficacy of apple polyphenol for treating cedar pollinosis.
(5/31)
A double-blind comparative study was conducted on cedar pollinosis patients in order to evaluate the treatment efficacy of apple polyphenol (Ap). Ap was administered (500 mg) once daily for 12 weeks, starting about 2 weeks prior to cedar pollen dispersion. Pollinosis symptoms during the study were evaluated according to the classification in the guidelines for allergic rhinitis diagnosis and treatment. The results show that the sneezing score was significantly lower for the Ap group than with the placebo group during the early period of pollen dispersion and during the main dispersion period. In addition, no adverse reactions were induced by Ap during the study. These results suggest that Ap may alleviate the symptoms of cedar pollinosis. (+info)
Structural basis for epitope sharing between group 1 allergens of cedar pollen.
(6/31)
The group 1 allergens are a major cause of cedar pollen hypersensitivity in several geographic areas. Allergens from several taxa have been shown to cross-react. The goal of these studies was to compare the structural features of the shared and unique epitopes of the group 1 allergen from mountain cedar (Jun a 1) and Japanese cedar (Cry j 1). An array of overlapping peptides from the sequence of Jun a 1 and a panel of monoclonal anti-Cry j 1 antibodies were used to identify the IgE epitopes recognized by cedar-sensitive patients from Texas and Japan. IgE from Japanese patients reacted with peptides representing one of the two linear epitopes within the highly conserved beta-helical core structure and both epitopes within less ordered loops and turns near the N- and C-termini of Jun a 1. A three-dimensional (3D) model of the Cry j 1, based on the crystal structure of Jun a 1, indicated a similar surface exposure for the four described epitopes of Jun a 1 and the homologous regions of Cry j 1. The monoclonal antibodies identified another shared epitope, which is most likely conformational and a unique Cry j 1 epitope that may be the previously recognized glycopeptide IgE epitope. Defining the structural basis for shared and unique epitopes will help to identify critical features of IgE epitopes that can be used to develop mimotopes or identify allergen homologues for vaccine development. (+info)
Clinico-immunologic evaluation of allergy to Himalayan tree pollen in atopic subjects in India--a new record.
(7/31)
Exposure to local pollen allergens has a direct bearing on the prevalence of allergic symptoms among the inhabiting atopic population. The populations in the Himalayas and around it are exposed to a variety of pollen grains from trees growing in the region, but the pollen-population interaction has not been clinically investigated. Himalayan tree pollen from five different taxa, i.e. Alnus nitida (AN), Betula utilis (BU), Cedrus deodara (CD), Mallotus phillipensis (MP) and Quercus incana (QI) were evaluated for their allergenicity in the Indian population by in vivo (skin prick test) and in vitro (ELISA) clinico-immunological methods. The presence of specific IgE against these tree pollen in the sera of skin test positive patients was taken as evidence for sensitization to these pollen. The average skin positivity in atopic populations recorded at different allergy centers in India varied from 2.2% against AN, to 4.7% against MP pollen. Significantly raised specific IgE against these pollen were observed in the sera of hypersensitive patients. The sensitization pattern to Himalayan tree pollen in these atopic populations varied. It was concluded that skin prick test positivity and raised IgE antibodies specific to AN, BU, CD, MP and QI established Himalayan tree pollen as important sensitizers in the atopic populations of India. A high incidence of skin sensitivity was observed to pollen antigens of Cedrus deodara, Mallotus phillipensis and Quercus incana in patients of Chandigarh residing in the hills and foothills of the Himalayas while Alnus nitida, Betula utilis and Cedrus deodara were important sensitizers in Delhi patients. The skin sensitization pattern against these pollen was in accordance with the level of exposure to these pollen of the subjects residing in that part of the country. (+info)
Escherichia coli O157:H7 in environments of culture-positive cattle.
(8/31)
Outbreaks of Escherichia coli O157:H7 disease associated with animal exhibits have been reported with increasing frequency. Transmission can occur through contact with contaminated haircoats, bedding, farm structures, or water. We investigated the distribution and survival of E. coli O157:H7 in the immediate environments of individually housed, experimentally inoculated cattle by systematically culturing feed, bedding, water, haircoat, and feed bunk walls for E. coli O157:H7 for 3 months. Cedar chip bedding was the most frequently culture-positive environmental sample tested (27/96 or 28.15%). Among these, 12 (44.0%) of positive bedding samples were collected when the penned animal was fecal culture negative. Survival of E. coli O157:H7 in experimentally inoculated cedar chip bedding and in grass hay feed was determined at different temperatures. Survival was longest in feed at room temperature (60 days), but bacterial counts decreased over time. The possibility that urine plays a role in the environmental survival of E. coli O157:H7 was investigated. Cedar chip bedding moistened with sterile water or bovine urine was inoculated with E. coli O157:H7. Bedding moistened with urine supported growth of E. coli O157:H7, whereas inoculated bedding moistened with only water yielded decreasing numbers of bacteria over time. The findings that environmental samples were frequently positive for E. coli O157:H7 at times when animals were culture negative and that urine provided a substrate for E. coli O157:H7 growth have implications for understanding the on-farm ecology of this pathogen and for the safety of ruminant animal exhibits, particularly petting zoos and farms where children may enter animal pens. (+info)