摘要:

A blechnoid type of spore wall developed inSchizaea pectinata(L.) Sw. consisting of inner and outer exospore, inner and outer perispore. The inner exospore was initiated by the formation of electron dense lamellae from the surface of the plasma membrane around each member of the tetrad. Tetrads were enclosed within chambers in the plasmodial tapetum. The outer exospore constituted the bulk of the spore wall and accumulated, at first, in irregular patches on the inner exospore; its deposition involved the activity of the plasma membrane of the plasmodial tapetum. A reticulate pattern developed on the outer exospore as a result of a differential pattern of growth involving plasmodial tapetum activity. The heterogeneous inner perispore was firmly attached to the outer exospore and its deposition involved structures found in the sporangial loculus. The outer perispore was loosely attached to the inner perispore and its formation was associated with composite bodies, which differed from the structures involved in inner perispore development, and consisted of partially polymerised sporopollenin, phenolics and silicon particles. Only the initiation of the inner exospore involved sporal activity, the development of the other parts of the spore wall were intimately associated with the plasmodial tapetum and with bodies present in the sporangial loculus.

ISSN:0017-3134    

DOI:10.1080/00173139509429049

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

A palynological study using LM and SEM was made of the morphology, ornamentation, apertural system and structure of the pollen wall, of the 18 species of the genusRubuswhich are present in the Iberian Peninsula. We demonstrate: a) the stenopalynous character of the genus (isopolar, subprolate, 3-lobate, 3-zonocolporate and striate-perforate, except forR. genevieriiwhose ornamentation is striate-gemmate-perforate and with a striated margin); b) the lalongate shape of the endoaperture, due to the disappearance or thinning of the nexine; and c) the existence of two structural types, Type I granular and Type II columellar with clearly-defined columellar spaces or compact without intercolumellar spaces.

ISSN:0017-3134    

DOI:10.1080/00173139509429050

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

The PAS reaction was used to stain total insoluble polysaccharides in whole pollen grains of anthers ofBorago officinalisandLycopersicum peruvianumfrom early microspore to ripe pollen stage. Total polysaccharide content was quantified with a microdensitometer: inBorago officinalisvalues showed two peaks, one during the microspore and the other during the binucleate stage; inLycopersicum, there was a single peak during the latter stage. In both species total polysaccharide content decreased markedly in the last stage of pollen development before anthesis, when starch was hydrolysed and the polysaccharide reserves of the pollen transferred to the cytoplasm. Pollen grain volume was also determined at the various stages. It was found to increase, though with a different pattern in the two species, and to decrease before dehiscence. The results are discussed in terms of cytoembryological data of pollen grain development.

ISSN:0017-3134    

DOI:10.1080/00173139509429051

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

The chemical composition of sporopolienin from pollen ofMagnolia grandifloraLinn. (Magnoliaceae) andHibiscus syriacusLinn. (Malvaceae) was investigated by several spectroscopic methods, such as X-ray photoelectron spectroscopy (XPS), infrared spectroscopy (IR) and UV-VIS absorption spectroscopy (UV-VIS). The results suggest that sporopollenin consists of only three kinds of element, C, H and O. We could not find any metalic components in sporopolienin. The detail study by XPS suggests that the carbon atom in sporopollenin is mainly aliphatic carbon. The present study implies that the main structure of sporopollenin is a simple aliphatic polymer containing aromatic or conjugated side chains.

ISSN:0017-3134    

DOI:10.1080/00173139509429052

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Present day lakes of all sizes, are “collectors” of pollen and spores from the vegetation cover of their watershed area. The pollen assemblages of their bottom sediments are 95% due to the effect of winds. In spite of a great variation in limnic characteristics, the decisive factor determining the composition of the subrecent spectra of the largest lakes is their enormous dimensions (Ladoga, Onega, Vozhe, Lacha, Kubenskoye, Ilmen and others) and their location within a single vegetation zone – middle and south taiga. The spectra of these lakes gives a highly averaged and floristically poor description of the vegetation at the highest taxonomic level – subzonal and formation-group. Pollen of the zonal vegetation – pine and spruce – predominates in the sediments. The smaller the water body (lakes of various types in the Karelian Isthmus and on the East Latvian Plateau), the greater is the influence of the surrounding vegetation cover (regional factor) on the pollen spectra. In small water bodies the regional and local elements of the vegetation cover are of great importance – birch, alder, willow and herbs belong to this group. The pollen of plants growing in the lake scarcely plays any part in those lakes investigated, despite their being strongly overgrown. This is due both to the exceedingly low pollen productivity of lake plants in comparison with that of terrestrial plants and to the destruction of pollen grains under the prevailing hydrodynamic and hydrochemical conditions, because their pollen have thin exines.

ISSN:0017-3134    

DOI:10.1080/00173139509429053

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

A study of the diurnal variations of airborne birch pollen in Sweden showed that the effect of rainfall on pollen counts is more complex than was previously thought. Most of the pollen counting sites in Sweden showed the same pattern of diurnal variations as described by other observers, i. e. lower concentrations during the early morning and a maximum in the middle of the day or early in the evening. Especially in one pollen counting site, viz, in Östersund, near the geographical centre of Sweden, we noted many occasions when the concentration of birch pollen increased concurrently with the beginning of heavy showers of rain. A few hours later the number of pollen grains decreased, when the pollen was washed out of the air. We noted great differences in the occurrence of such pollen peaks between different parts of the country. The phenomenon was more frequent in Östersund than in Stockholm, maybe due to the differing topography. Heavy rains seem to be more influential if large amounts of pollen have previously been brought high up into the air, e.g. by warm air or by long-distance transport of pollen, and this should be considered when making pollen forecasts.

ISSN:0017-3134    

DOI:10.1080/00173139509429054

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Seasonal and diurnal changes in concentrations of airborne basidiomycete spores (basidiospores, rusts, smuts) were studied, using Burkard volumetric spore traps, in two areas of Mexico City with different degrees of urbanization and related to changes in climatic variables through 1991. Basidiomycete spores formed a large component of the total airborne fungal spore load in the atmosphere of Mexico City. They were the second most abundant spore type after Deuteromycotina (Hyphomycetes), forming 32% of the total fungal spores trapped in an urban-residential area and 28% in an urban-commercial area. The most abundant basidiomycete spores were basidiospores although smut-type spores were trapped on more days than basidiospores and rusts on fewer. Basidiospores occurred in concentrations up to 2,000 spores m-3 in the urban-residential area. Basidiospores showed a marked seasonal distribution, especially in the southern area, with their greatest abundance during the wet season. The correlation coefficients associated with regressions between basidiospore concentration and some environmental factors were increased when a lag period of 2 to 4 days was used between environmental measurements and the day of spore collection. Basidiospore concentrations exceeded the 75 percentile concentration (>400 spores m-3) most often when rainfall was up to 6 mm and relative humidity was >70%. Basidiospores showed a diurnal periodicity with greatest concentrations in the early morning. The most common basidiospore type wasCoprinuswhich formed 67% of basidiospores trapped in the southern area and 63% in the central area. Smut spores were trapped on 87% of days through the year while rust spores occurred in only 35%. Both rusts and smuts were present in only small concentrations.

ISSN:0017-3134    

DOI:10.1080/00173139509429055

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Fungal spores are suspected of being responsible for the allergy of bakers and pastry makers. In the same town, and for 14 bakeries, a survey has been carried out of the species of filamentous fungi found in the atmosphere of the bakehouses and in the flour used. Results show considerable quantitative and qualitative variations in the mycoflora. The genusCladosporium, considered as extremely allergy provoking, could play an important role. The layout of the sites and congestion due to intense activity strongly favour the dispersion of spores in the surrounding atmosphere and at the same time increase the risk of allergy.

ISSN:0017-3134    

DOI:10.1080/00173139509429056

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

ThreeSecale cerealepollen batches, harvested by different procedures and supplied by manufacturers from different countries, were parallelly incubated in phosphate buffer saline, pH 7. 4. The extracts obtained showed differences both in proteic and allergenic composition.

ISSN:0017-3134    

DOI:10.1080/00173139509429057

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

ISSN:0017-3134    

DOI:10.1080/00173139509429058

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor