摘要:

A survey of airborne pollen was conducted during 1984 in the coastal plain of Israel. The flora of that area is continuously changing due to urbanization and agriculture, thus affecting the airborne pollen spectrum.

ISSN:0017-3134    

DOI:10.1080/00173139109432013

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

In many, mostly temperate regions of the world, crops are cultivated in completely or partly closed environments. Problems concerning the dissemination of fungal spores or bacterial cells in these systems are comparable to those in open systems, but there are many supplementary problems, which have hardly been investigated up to now.

ISSN:0017-3134    

DOI:10.1080/00173139109432014

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

In 1988 and 1989 a plot containing 668 sunflower plants (cv. Sunbred 246) was inoculated with similar amounts of sclerotia ofSclerotinia sclerotiorumin February or March and disease development was monitored on each plant during the summer. The concentration of airborne ascospores in the plots was measured and was found to correspond to the number of apothecia. In both years ascospore production started early in June and in 1988 reached a peak in mid-July and lasted until the beginning of August. However, in 1989 ascospore production only lasted for about two weeks and airborne concentrations were small. Ascospores were released predominantly during the day, mostly around 1200 BST. Disease symptoms were not observed until July, between 25 and 40 days after ascospores were first found. Disease incidence increased roughly linearly with time until mid-August when the rate of infection declined. In 1988 the number of plants per week with new symptoms was roughly proportional to the average ascospore concentration measured 5 weeks previously. The observations suggest that severity of disease may be related to ascospore concentration during the infection period.

ISSN:0017-3134    

DOI:10.1080/00173139109432015

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

An aeroallergen survey in two provinces, Chiangmai in the northern and Songkhla in the southern part of Thailand which are 1 500 km apart, was done in 1986 and 1987 using a rotorod sampler. The five most common pollen types and mold spores were: Chiangmai: Mold spores:Cladosporium, rust,Fusarium, Nigrospora, 1-celled spore. Pollen grains:Mimosa, wild grasses, Urticaceae, Cyperaceae, tetrad pollen. Songkhla: Mold spores:Cladosporium, rust,Nigrospora, Papularia, 1-celled spore. Pollen grains:Casuarina, Mimosa, Urticaceae, Cyperaceae, wild grass. There were definite differences in the amount and frequency of occurrences of aeroallergens between these two provinces. Furthermore, some specific pollen and mold spores, such as tetrads andMimosapollen, were found only in Chiangmai, andCasuarinapollen andPapulariaspores only in Songkhla. These findings might be caused by the differences in geography, plantation and meteorological data.

ISSN:0017-3134    

DOI:10.1080/00173139109432016

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

Parthenium hysterophorus, a recently invaded toxic weed, in Eastern India, is now growing gregariously in Salt Lake City — a newly developed township situated in the eastern fringe of the metropolitan city of Calcutta. The floristic survey revealed that most of the trees and shrubs in Salt Lake City have been introduced except for a few, which were recorded as natural occurrence,Partheniumbeing most prevalent among them. Ecological associations ofPartheniumin various localities of Salt Lake City were also investigated. Aerobiological survey was done using a Burkard seven day Volumetric Spore Trap, with the object to record the occurrence ofPartheniumpollen in the air of Salt Lake in different seasons along with other airborne types. A total of 45 pollen and 60 fungal spore types were trapped and recorded. The frequency of grass and cyperaceous pollen were found to be dominant followed byTrema. Frequency ofPartheniumwas relatively insignificant. Chemical analyses of the pollen grains ofPartheniumincluding assay of carbohydrate, lipid, protein, etc., were done. Clinically one out of six patients showed ELISA positive reaction toPartheniumpollen.

ISSN:0017-3134    

DOI:10.1080/00173139109432017

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

Terrestrial life can be schematically described as organic molecules organized in liquid water. According to Oparin's hypothesis, organic building blocks required for early life were produced from simple organic molecules formed in a primitive reducing atmosphere. Precursors of lipids, nucleic acids and enzymes obtained in the laboratory under simulating conditions are reviewed. Geochemists favor now a less reducing atmosphere dominated by carbon dioxide. In such an atmosphere, very few building blocks are formed under prebiotic conditions. Import of extraterrestrial organic molecules may represent an alternative supply. Experimental support for such an alternative scenario is examined in comets, cosmic dust, meteorites and micrometeorites. Even the prebiotic broth receives today severe criticism for being implausible. In contrast to the classical scenario, a chemoautotrophic origin of life is discussed. Finally, interesting information related to early terrestrial life may be gained from Mars exploration.

ISSN:0017-3134    

DOI:10.1080/00173139109432018

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

Within 40 years of experimental studies in prebiotic chemistry, most of the building blocks of the living systems have been synthesized in plausible conditions of the primitive Earth. The starting ingredients correspond to two complementary classes: volatile organics, and their non volatile oligomers. They may have been formed in the atmosphere on the primitive Earth and/or imported by extra-terrestrial sources. Organic chemistry is involved in meteorites, comets, in the giant planets and several of their satellites. Again this chemistry presents the two complementary aspects. In particular, with a dense reduced atmosphere rich in organic compounds in gas and aerosol phases, Titan appears as a natural laboratory for studying prebiotic chemistry at a planetary scale.

ISSN:0017-3134    

DOI:10.1080/00173139109432019

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

The elucidation of the ultrastructural cytochemistry, coupled with chemical stabilizing procedures during fixation and embedding, make a significant contribution to the understanding of pollen-exine ontogenesis. A combination of the Con-A agglutination and lanthanum precipitation methods proved particular advantageous during the intine formation stage. By using immunogold techniques, it is possible to demonstrate that only the mature exine of the atmospheric pollen grains reacted positively after sectioning, not the intine. An important difference appears when immature pollen grains are treated under the same conditions: in this case, both the microsporal cytoplasm of the future pollen grain and the immature exine react, but not the intine.

ISSN:0017-3134    

DOI:10.1080/00173139109432020

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

The mineral composition of the exine of two male date palms “Deglet-noor” and “Takerboucht” was examined with Electronic Probe X Micro Analysis. Fresh pollen grains were (1). dried naturally and untreated, (2). lyophilized, (3). Gamma-ray irradiated, and analysed. Their composition is compared. A slight distinction between these two male date palms is established.

ISSN:0017-3134    

DOI:10.1080/00173139109432021

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

Pollen was collected from different cultivated varieties ofDactylis glomeratain 1986, 1987 and 1988 and compared with an undifferentiated stock ofDactylis glomeratapollen harvested and stored dry at +4°C since 1981. The allergen content of the crude pollen extracts was established on the basis of the IgE antibodies from the sera of three different patients allergic to grass pollen, using the nitrocellulose immunoprint technique following isoelectric focusing (IEF) and separation in agarose gels. Coomassie blue and silver staining patterns were also compared. They showed some marked differences in the isoelectric points of the constituants of these extracts. Using this major allergen recognition by patient sera as a selection criteria we were able to delimit 8Dactylisvarieties with low or undetectable Dac g IV allergen amounts and 7 varieties which contained this allergen. Two other allergens used as markers enabled us to suggest a kind of taxonomy, based upon the allergen presence, of these 15 varieties. The effect of the storage temperature was studied for 8 different varieties kept at +4°C, -20°C and -40°C. The allergen recognition and silver staining patterns after IEF separation of the crude pollen extracts revealed a selective persistance of some constituants and the disappearance of others at +4°C. The effect of freeze-drying was also analysed in the same way. Finally the pollen constituants of oneDactylis glomeratavariety, harvested in 1986 and 1987 and kept at different temperatures were compared using the same techniques.

ISSN:0017-3134    

DOI:10.1080/00173139109432022

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor