27 resultados para Grass spikelet


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In Melbourne, a southern hemisphere city with a cool temperate climate, the grass pollen season has been monitored using a Burkard spore trap for 12 years (11 pollen seasons, which extend from October through January). The onset of the grass pollen season (OGPS) has been defined in various ways using both arbitrary cumulative scores (Sum 75, Sum 100) and percentages (10% Pollen Fly). OGPS, based on the forecast model of pollen season devised by Lejoly-Gabriel (Acta Geogr. Lovan., 13 (1978) 1–260) has been most widely used in efforts to forecast the beginning of the pollen season. OGPS occurred in Melbourne between 20 October to 24 November (average 6 November), a difference of 35 days. Duration of the pollen season ranged from 46 to 81 days, with a mean of 55 days, one of the longest reported. The relationships between onset and various weather parameters for July have enabled us to modify a model, using linear regression analysis, to predict onset. The prediction model is based on a negative correlation between date of onset and the sum of rainfall for July (a winter month). The error of prediction (Ep) is 24% and predicted day of OGPS was precisely predicted on 2 occasions, and on others with a range of accuracy of 3 to 14 days.

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Background Grass pollen allergens are known to be present in the atmosphere in a range of particle sizes from whole pollen grains (approx. 20 to 55 μim in diameter) to smaller size fractions < 2.5 μ (fine particles, PM2.5). These latter particles are within the respirable range and include allergen-containing starch granules released from within the grains into the atmosphere when grass pollen ruptures in rainfall and are associated with epidemics of thunderstorm asthma during the grass pollen season. The question arises whether grass pollen allergens can interact with other sources of fine particles, particularly those present during episodes of air pollution.

Objective We propose the hypothesis that free grass pollen allergen molecules, derived from dead or burst grains and dispersed in microdroplets of water in aerosols, can bind to fine particles in polluted air.

Methods We used diesel exhaust carbon particles (DECP) derived from the exhaust of a stationary diesel engine, natural highly purified Lol p 1, immunogold labelling with specific monoclonal antibodies and a high voltage transmission electron -microscopic imaging technique

Results DECP are visualized as small carbon spheres, each 30–60 nm in diameter, forming fractal aggregates about 1–2μ in diameter. Here we test our hypothesis and show by in vitro experiments that the major grass pollen allergen, Lol p I. binds to one defined class of fine particles, DECP.

Conclusion DECP are in the respirable size range, can bind to the major grass pollen allergen Lol p I under in vitro conditions and represent a possible mechanism by which allergens can become concentrated in polluted air and thus trigger attacks of asthma.

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Isolation of gene transcripts from desiccated leaf tissues of the resurrection grass, Sporobolus stapfianus, resulted in the identification of a gene, SDG8i, encoding a Group 1 glycosyltransferase (UGT). Here, we examine the effects of introducing this gene, under control of the CaMV35S promoter, into the model plant Arabidopsis thaliana. Results show that Arabidopsis plants constitutively over-expressing SDG8i exhibit enhanced growth, reduced senescence, cold tolerance and a substantial improvement in protoplasmic drought tolerance. We hypothesise that expression of SDG8i in Arabidopsis negatively affects the bioactivity of metabolite/s that mediate/s environmentally-induced repression of cell division and expansion, both during normal development and in response to stress. The phenotype of transgenic plants over-expressing SDG8i suggests modulation in activities of both growth- and stress-related hormones. Plants overexpressing the UGT show evidence of elevated auxin levels, with the enzyme acting downstream of ABA to reduce drought-induced senescence. Analysis of the in vitro activity of the UGT recombinant protein product demonstrates that SDG8i can glycosylate the synthetic strigolactone analogue GR24, evoking a link with strigolactone-related processes in vivo. The large improvements observed in survival of transgenic Arabidopsis plants under cold-, salt- and drought-stress, as well as the substantial increases in growth rate and seed yield under non-stress conditions, indicates that overexpression of SDG8i in crop plants may provide a novel means of increasing plant productivity.

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Sporobolus stapfianus Gandoger, one of ~40 known ‘anabiotic’grass species (i.e. ‘able to regain vital activity from a state of latent life’), is the most versatile tool for research into desiccation tolerance in vegetative grass tissue. Current knowledge on this species is presented, including the features that suit it for investigations into the plant’s ability to survive dehydration of its leaf protoplasm. The main contributors to desiccation tolerance in S. stapfianus leaves appear to be: accumulation during dehydration of protectants of membranes and proteins; mechanisms limiting oxidative damage; a retention of protein synthetic activity in late stages of drying that is linked with changes in gene expression and in the proteomic array; and an ability to retain net synthesis of ATP during drying. S. stapfianus exemplifies an advanced stage of an evolutionary trend in desiccation tolerant plants towards increased importance of the dehydration phase (for induction of tolerance, for synthesis of protectants and for proteomic changes).

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Environmental conditions may influence the presence and strength of competitive interactions between different life forms, thereby shaping community composition and structure, and corresponding fuel dynamics. Woodland and shrubland communities of the Mediterranean climate region of South Eastern Australia contain a varied mixture of herbaceous and woody plants. The ratio of herbaceous to woody plants changes along gradients of temperature, moisture and soil fertility. This study aimed to experimentally examine the relative importance of, and interactions between environmental controls (moisture and soil fertility) on the balance of dominant herbaceous (Triodia scariosa) and woody plants (e.g. Acacia ligulata and Leptospermum coriaceum) and their ultimate effects on fuel and fire regimes. The results suggest that environmental determinants of the growth of T. scariosa are likely to be more important than interactions with shrubs in controlling the distribution of T. scariosa. The growth of T. scariosa was consistently higher under hot temperatures and on the less fertile yellow sands, which dominate the south of the region. The results suggest that there is strong potential for the distribution and abundance of T. scariosa to be altered in the future with changes in temperature associated with climate change. The distribution of soil types across the Mediterranean climate region of South Eastern Australia may be predisposed to favour the southerly expansion of T. scariosa-dominated communities in the future under a warmer climate.

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This paper examines the activities of a group of heritage enthusiasts in Iran. Grass roots heritage activism is a relatively recent phenomenon that appeared in Iran since the late 1990s. They are increasingly operating collectively as cultural or heritage NGOs. They have diverse socio-economic origins and political views. However, as this paper argues, they share a common ground in their activities; one that maintains an ambivalent and critical relationship with the state and official definitions of heritage and identity. Referring to interview and other data collected during fieldwork in Iran, this paper traces and analyses the contours of that common ground and argues that there is a nascent heritage movement in the country. The impact and contribution of these emerging and self-reflective heritage movements to Iranian identity, which is reflected in their embracing of diversity and the notion of historical continuity, reveal the dynamism and complexity of the cultural and political landscape of contemporary Iranian society. They also reveal the importance of generating further scholarship in the field of Iranian cultural heritage. In conceptualising the characteristics of a nascent heritage movement in Iran, the paper makes a new contribution to the approach of existing scholarship in the broader field of heritage studies.

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In recent years, sport entities have begun to prioritise environmental sustainability (ES) initiatives in their business strategies with the aim of minimising their environmental impact and engaging stakeholders within the ES movement. There has been minimal academic consideration of the ES movement in professional sport, particularly outside of North America and Europe. The aim of the present study is to provide an overview of the type and profile of ES initiatives being undertaken and communicated to stakeholders in the Asia-Pacific region by the industry bodies. Further, the study offers a conceptual model of the global-, country-, industry- and organisational-level forces impacting these sporting organisations’ ES practices. Various communication mediums of 114 professional sport teams from seven countries—Australia, India, New Zealand, Japan, China, Taiwan and Korea—were evaluated using content analysis. The results reveal low communication of ES practices by professional sport teams in the Asia-Pacific region compared to North America. Extended findings on the existing global profile of ES engagement provide a descriptive understanding of the ES movement in the Asia-Pacific region, and contribute to the identification of possible antecedents and correlatives to be evaluated in future research.