摘要:

The origin and formation of the pollen wall and Ubisch bodies of wheat (Triticum aestivum) have been investigate d. Two layers of callose surround the developing sporocyst: the first layer formed [MATTER UNCLEAR IN PDF FILE]e ual in distribution and is believed to push the sporocyst against the tapetum, while [MATTER UNCLEAR IN PDF FILE]second layer completely surrounds each cell and is believed to act as a temporary wall [MATTER UNCLEAR IN PDF FILE] cell develops. The pollen wall is initiated in conjunction with the plasma membrane. The plasma membrane protrudes toward the microspore coat and at the end of each protrusion there is a small patch of electron dense material that is the beginning of the probacules. The probacules continue to enlarge and the protectal fibrillar-reticulate pattern becomes evident. A trilamellar structure forms on the surface of the plasma membrane. Material deposited on this structure appears to be the beginning of the foot layer. Eventually the foot layer increases in thickness and connects the bases of the probacules. The reticulate pattern of both the tectum and the foot layer becomes clearly visible. The deposition of sporopollenin appears to take place on the sides and to extend toward the center of each reticulate unit forming the microchannels. Strands are formed at the proximal surface of the foot layer. These strands accumulate little sporopollenin on their surface and they represent a rudimentary endexine inTriticum. As the vacuole develops in the pollen grain, the endexine becomes appressed to the foot layer and can no longer be seen. The Z-layer forms between the endexine and the plasma membrane. As development continues, the intine forms between the Z-layer and the plasma membrane. Pre-Ubisch bodies are formed within the tapetal cells and pass through the plasma membrane. These form the core of the Ubisch bodies and it is on these that sporopollenin is deposited. The formation of the Ubisch bodies closely follows the pattern described for the pollen wall.

ISSN:0017-3134    

DOI:10.1080/00173138609429929

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Confusion over the proper nomenclature and differential effectiveness of ethanolamine and several closely related organic solvents has led to some ambiguity in the use of these compounds in the study of pollen wall stratification. Ethanolamine, diethanolamine and triethanolamine are internationally accepted synonyms for 2-aminoethanol (H2NCH2CH2OH), 2,2′-dihydroxydiethylamine (NH(CH2CH2OH)2), and 2,2′,2″-trihydroxytriethylamine ((HOCH2CH2)3N), respectively, and it is suggested that these simple synonyms be used in palynological investigations. Ethanolamine and diethanolamine are demonstrated to be the most effective solvents for selectively removing the outer ektexine of angiosperm pollen walls without destroying the inner endexine layer. In addition, fixation techniques and age of pollen samples are shown to affect the reactivity of the exine to each solvent in both dicotyledon (Passiflora, Ipomoea) and monocotyledon (Gladiolus) pollen. Conflicts between ontogenetic and chemical criteria for recognizing the presence of endexine suggest that cytochemical tests should be used in conjunction with, or in preference to, developmental evidence for stratified nexines.

ISSN:0017-3134    

DOI:10.1080/00173138609429930

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

The application of the freeze fracture and cytoplasmic maceration technique to mature pollen grains is described. In this method anthers are freeze fractured and the cytoplasm of exposed cells is macerated by treatment with a dilute solution of osmium tetroxide. When examined in the scanning electron microscope the specimens reveal details of cell walls and membraneous organelles. It is possible to examine fractured pollen walls complete with intine, the inner surface of which may possess endosculpturing. The disposition of pollen grains within anthers and such features as pollen connecting viscin threads may be studied with the technique.

ISSN:0017-3134    

DOI:10.1080/00173138609429931

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Results of five years of continuous monitoring of airborne pollen concentrations with a volumetric trap in Leiden indicate that almost 36% of the total pollen count originates from a group of 23 taxa, herbs and weeds flowering in the summer, between May and October. More than 95 % of the airborne summer-weed pollen are fromUrtica, Rumex, Artemisia, Plantago, and Chenopodiaceae,Urticapredominating with over 85%. Of the three most frequent summer-weed pollen types, bothRumexandUrticashow variable seasonal patterns, whereasArtemisiais more constant. Although large concentrations ofUrticapollen are often found, allergic sensitization is infrequent. The converse is true ofArtemisiapollen, which could be a cause of pollinosis in August in spite of the relatively low concentrations in the air.

ISSN:0017-3134    

DOI:10.1080/00173138609429932

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Pollen production in terms of number per anther along with the particulars of anther number per flower, anther length, filament length, pollen grain size and mode of anther dehiscence was determined for 82 angiospermous plant species occurring in Andhra Pradesh, India. Pollen production varied widely from genus to genus, and from species to species within the same genus. The non-Poaceae and non-Cyperaceae members proved to be high pollen producers. The level of pollen production was directly related to anther size and inversely related to pollen grain size. There was no correlation between high pollen production and mode of anther dehiscence in general, but the high pollen producers of Poaceae are porous dehiscing. It is presumed that high pollen producers are crosspollinated, whereas low pollen producers are either self-pollinated or apomictic.

ISSN:0017-3134    

DOI:10.1080/00173138609429933

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Using a gravimetric slide collector we carried out air-sampling studies near the city of Caracas to add to the sparse data presently available to local allergists. During one year we collected 11093 pollen grains and fern spores that were divided into 68 different morphological groups. Thirty of these, which include all the most commonly found varieties, are classified and illustrated in the present work.

ISSN:0017-3134    

DOI:10.1080/00173138609429934

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Studies of the atmosphere in Venezuela disclosed that a large variety of airborne fungus spores may be trapped by a simple gravimetric method. Thirty-three of the 143 different types trapped in one year were tentatively identified. The one-year study indicates that the direct examination of exposed slides may be more effective in revealing the large variety of mould spores carried by the air than colony counting from exposed culture plates.

ISSN:0017-3134    

DOI:10.1080/00173138609429935

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

The dogma that anemophily in the humid tropics is rare or even absent is challenged. Long pollen rain shadows, leptokurtic pollen distribution patterns, and electrostatic attractions between pollen and stigma may contribute to successful abiotic pollination among plants whose mechanisms bridge a continuum between the extremes of anemophily and zoophily. Representatives of 21 families of woody, neotropical plants are shown to possess some form of abiotic pollination or pollen dispersal, suggesting a greater role of anemophily in tropical reproductive biology and allergic responses than previously assumed.

ISSN:0017-3134    

DOI:10.1080/00173138609429936

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Efforts to evaluate the roles and overall levels of allergens carried by microaerosols remain preliminary. It is not clear what range of allergen specificities may yet be recovered from small particle fractions under suitable analysis. However, it now appears that airborne units sized below 10 μm may contribute, perhaps substantially, to inhaled allergen burdens. Innovative application of filters and high speed impingers, as well as of immunoassays, should increasingly clarify the clinical roles of such previously overlooked, small aerosols.

ISSN:0017-3134    

DOI:10.1080/00173138609429937

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Two types of unusual transport mechanisms of antigens are described, one involving caterpillar hairs (setae) of gypsy moths, and the other involving grass pollen attracted to plastic sleds of an Alpine slide. Antigenic sources, investigations into peculiar mechanisms of spread, and impact of these antigens on allergic people are discussed. Each type affected allergic people in a different fashion, yet each type was associated with its own characteristically similar symptom complex. Natural factors terminated the gypsy moth antigen spread, but active interference into the Alpine slide antigen cycle was required for control.

ISSN:0017-3134    

DOI:10.1080/00173138609429938

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor