Effects of self-, chase and mixed self/cross-pollinations on pistil longevity and fruit set in Ceiba species (Bombacaceae) with late-acting self-incompatibility. (1/7)

BACKGROUND AND AIMS: Late-acting self-incompatibility (LSI), in which selfed flowers fail to form fruits despite apparently successful growth of the pollen tubes to the ovules, is a contentious and still poorly understood phenomenon. Some studies have indicated pollen tube-pistil interactions, and major gene control. Others favour an early acting inbreeding depression explanation. METHODS: Experimental pollinations, including selfs (in a subsample of which the style was cut before pollen tubes reached the ovary), chase self/cross-pollinations, crosses, and mixed self/cross-pollinations were used to study floral/pistil longevity and effect on fruit set and seed yield in two Ceiba species known to have LSI. RESULTS: Self-pollinations, including those with a cut style, had extended floral longevity compared with unpollinated flowers. Chase pollinations in which cross-pollen was applied up to 3 h after selfing set fruits, but with reduced seed set compared with crosses. Those with cross-pollen applied at 4 and 8 h after self-pollination all failed to set fruits. Flowers subjected to 1 : 1 and 2 : 1 self/cross-pollinations all produced fruits but again with a significantly lower seed set compared with crosses. CONCLUSIONS: Extended floral longevity initiated with self-pollen tubes growing in the style indicates some kind of pollen tube-pistil interaction. Fruit set only in chase pollinations up to 3 h implies that self-pollen tubes either grow more slowly in the style or penetrate ovules more slowly on arrival at the ovary compared with cross-tubes. This agrees with previous observations indicating that the incidence of penetrated ovules is initially lower in selfed compared with crossed pistils. However, the low seed yield from mixed pollinations indicates that self- and cross-pollen tubes arrive at the ovary and penetrate ovules more or less simultaneously. Possible explanations for these discordant results are discussed.  (+info)

House dust mite allergen levels in Chiang Mai homes. (2/7)

The quantitative assays for house dust mite (HDM) allergens provide a valid index of exposure and can be used for risk evaluation. We assessed group I HDM allergen levels in mattress and living room floor dust from 35 Chiang Mai homes and identified factors associated with high allergen levels. One-third of mattress and living room floor dust had group I HDM allergen levels of between 2-10 microg/g. Two-thirds of mattress dust and a small amount of living room floor dust had group I HDM allergen levels of over 10 microg/g. The geometric means of Der p I, Der f I and total group I allergens in mattress and living room floor dust were 8.61, 2.88, and 15.81 microg/g and 1.61, 0.27 and 2.43 microg/g, respectively. Mattresses made of kapok and rugs kept in the living room were associated with high group I allergen levels.  (+info)

The accumulation of dust mite allergens on mattresses made of different kinds of materials. (3/7)

BACKGROUND: Different mattress materials may affect the accumulation of allergens. OBJECTIVE: To compare the amount of group 1 dust mite allergens (Der p1 + Der f1) on mattresses made of different kinds of materials before and after use. METHODS: Sixty new mattresses made of kapok, synthetic fiber, coconut fiber and sponge-like polyurethane, were placed in the house officers' dormitory at Siriraj hospital, Thailand. The dust samples were collected before (0), 1, 2, 3, 6, 9 and 12 months after the mattresses were used. Group 1 dust mite allergens were analyzed using two-site monoclonal antibody ELISA. RESULTS: Der f1 made up 86.7 % of group 1 allergens found in the matress dust. After the 2nd month, only the mean level in sponge-like polyurethane mattress was under 2 microg/g dust (sensitized level). At the 6th month, the mean levels were 13.1 in coconut, 21.7 in kapok and 17.3 microg/g dust in synthetic fiber, all of which were more than 10 microg/g dust (symptomatic level). At the 9th month, the level in sponge-like polyurethane mattress was increased to 11.2 microg/g. At 12th month the level in coconut fiber, sponge-like polyurethane synthetic fiber and kapok mattresses were 20.2, 22.4, 28.9 and 32.2 microg/g dust respectively. CONCLUSIONS: The accumulation rate in kapok and synthetic mattresses was significantly higher than coconut and sponge-like polyurethane mattresses. The mean level of group 1 mite allergens exceeded 10 microg/g dust after the 6th month of use in coconut fiber, kapok and synthetic fiber and at the 9th month in sponge-like polyurethane mattress.  (+info)

At3g08030 transcript: a molecular marker of seed ageing. (4/7)

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Root-shoot allometry of tropical forest trees determined in a large-scale aeroponic system. (5/7)

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Arbuscular-mycorrhizal networks inhibit Eucalyptus tetrodonta seedlings in rain forest soil microcosms. (6/7)

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Long-term effects of habitat fragmentation on mating patterns and gene flow of a tropical dry forest tree, Ceiba aesculifolia (Malvaceae: Bombacoideae). (7/7)

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