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1.
A polyclonal antiserum and monoclonal antibodies have been prepared to purified pollen exines of Calocedrus decurrens Florin. The location of the antigen is in the exine, as shown by light-and electron-microscopic immunocytochemistry. The greatest reduction in antibody binding follows treatment of the exine with chemicals known to alter sporopollenin. These results provide evidence that sporopollenin is antigenic. Exines of ten species of gymnosperms and angiosperms also bound the polyclonal antiserum, indicating similarity of sporopollenin structure. 相似文献
2.
Summary During an earlier investigation, microtubules were observed at the periphery of invasion processes in the developing syncytial tapetum ofTradescantia virginiana L. They were also associated with membranous sacs that accumulate adjacent to tetrads, with putative fusion sites where the tapetal plasmodium is initiated, and, in postmeiotic stages, with the perispore membrane that encloses the developing spore cells. Colchicine was administered to developing flower buds to investigate the roles of these microtubules. The results indicate that microtubules neither initiate nor guide the tapetal invasion of the loculus. The treatments, however, resulted in absence of cell coat from invasion processes and prevention of cell fusion. They also inhibited polarized migration of membrane sacs and removed the associated microtubules. The development of an organized secretory apparatus at the perispore membrane was disrupted, with subsequent disordered deposition of sporopollenin in the extracellular spaces of the partially-fused plasmodium. The results suggest that microtubules participate in the formation and internal spatial organization of the tapetal plasmodium, and establishment of a secretory surface that normally produces sporopollenin at the tapetum-microspore interface. 相似文献
3.
Subunits of forming pollen exine and Ubisch bodies as seen in freeze substitutedLedebouria socialis Roth (Hyacinthaceae) 总被引:1,自引:0,他引:1
Summary High-pressure freezing/freeze substitution/TEM was employed to investigate anthers of the monocotyledonous angiospermLedebouria socialis Roth (Hyacinthaceae) during early tetrad stage. The initials of the outer sporopollenous pollen wall stratum (=sexine) and of the homologous tapetal products (=Ubisch bodies) are composed of highly regular subunits: clustered globules with a constant diameter of approximately 28 nm. The clusters develop within diffuse accumulations of electron-dense material. This process, interpreted as sporopollenin polymerization, does not necessarily depend on the presence of membrane-bound enzymes. Immunogold labeling with JIM 5 and JIM 7 antibodies revealed that the primexine as well as the dissolving tapetal cell walls, the sites of sexine and Ubisch body formation, respectively, contain un-esterified and methyl-esterified pectins.Abbreviations E-PTA
ethanolic phosphotungstic acid
- PA
periodic acid
- UA/Pb
uranyl acetate/lead 相似文献
4.
Scenedesmus obliquus, strain 633, which synthesizes ketocarotenoids and sporopollenin, also forms pink-red-colored cell walls. Both the cell walls left over after autospore liberation and those from homogenates of disrupted green cells have similar carotenoid pigmentation. Canthaxanthin, astaxanthin, an unidentified ketocarotenoid, and lutein were found as integral cell wall components. They are bound to the outer (trilaminar) layer of the complete cell wall which also contains sporopollenin.Abbreviations CWH
complete cell walls isolated from the homogenates
- CWM
maternal cell walls accumulated in the medium
- KC
ketocarotenoid
- SC
secondary carotenoids
- SP
sporopollenin 相似文献
5.
Biogenesis and function of the lipidic structures of pollen grains 总被引:31,自引:0,他引:31
Pollen grains contain several lipidic structures, which play a key role in their development as male gametophytes. The elaborate
extracellular pollen wall, the exine, is largely formed from acyl lipid and phenylpropanoid precursors, which together form
the exceptionally stable biopolymer sporopollenin. An additional extracellular lipidic matrix, the pollen coat, which is particularly
prominent in entomophilous plants, covers the interstices of the exine and has many important functions in pollen dispersal
and pollen-stigma recognition. The sporopollenin and pollen coat precursors are both synthesised in the tapetum under the
control of the sporophytic genome, but at different stages of development. Pollen grains also contain two major intracellular
lipidic structures, namely storage oil bodies and an extensive membrane network. These intracellular lipids are synthesised
in the vegetative cell of the pollen grain under the control of the gametophytic genome. Over the past few years there has
been significant progress in elucidating the composition, biogenesis and function of these important pollen structures. The
purpose of this review is to describe these recent advances within the historical context of research into pollen development.
Received: 1 November 1997 / Revision accepted: 3 February 1998 相似文献
6.
Summary Exines fromTypha angustifolia L. pollen were dissolved in hot 2-aminoethanol. The solubilisate was successively fractionated and reaggregated via a dialysis cascade with dialysis tubings of different exclusion volumina. Four fractions of reaggregated material with different molecular mass were obtained. Fraction 1 with a molecular mass above 25,000 Da, fraction 2 with a molecular mass between 10,000–25,000 Da, fraction 3 with a molecular mass between 5,000–10,000 Da, and fraction 4 of a molecular mass lower than 5,000 Da. The fractions were comparatively analysed by scanning and transmission electron microscopy and X-ray microscopy. The material of the fractions with a molecular mass above 10,000 Da exhibit high congruence to the initial material. Analysis of the reaggregated material with the lowest molecular mass revealed special distinct substructures which in form and size showed high similarities to substructures of exines described in literature. In detail, spherical substructures consisting of an electron-dense core surrounded by an electron-transparent corona and in addition elongated substructures with a distinctive surface sculpture were detected.Abbreviations SEM
scanning electron microscopy
- TEM
transmission electron microscopy 相似文献
7.
Pollen sporopollenin: degradation and structural elucidation 总被引:1,自引:0,他引:1
E. Domínguez José A. Mercado Miguel A. Quesada A. Heredia 《Sexual plant reproduction》1999,12(3):171-178
We report the isolation of purified sporopollenin from pollen grains of different species and its complete solubilization.
Exine from Pinus pinaster, Betula alba, Ambrosia elatior and Capsicum annuum was extracted by treatment with hydrogen fluoride in pyridine. These exines were purified from their aromatic moieties and
from fatty acids linked by ester bonds using acidolysis and saponification treatments. The biopolymer obtained retains almost
completely the shape of the original pollen grain. Fourier-transform infrared spectroscopy analysis of the isolated sporopollenin
showed the absence of polysaccharide and phenolic material and the presence of carboxylic acid groups joined to unsaturations
and ether linkages. Sporopollenin samples were successfully degraded by exhaustive 24-h ozonolysis at room temperature. Gentle
ozonolysis (3 h at 0°C) did not completely degrade the biopolymer. The compounds obtained after exhaustive ozonolysis were
analysed by gas chromatography-mass spectrometry. Dicarboxylic acids with a low number of carbon atoms were identified as
major components of sporopollenin from P. pinaster, A. elatior and C. annuum, representing 28.8%, 63.2% and 88.5%, respectively, of the total compounds obtained. Fatty acids and n-alkanes also were identified in P. pinaster, A. elatior and B. alba sporopollenin. From the data obtained, an hypothesis about the chemical nature and structural arrangement of the sporopollenin
is proposed.
Received: 8 November 1998 / Revision accepted: 14 April 1999 相似文献
8.
Summary In order to identify factors necessary for the establishment of the reticulate pollen wall pattern, we have characterized a T-DNA tagged mutant ofArabidopsis thaliana that is defective in pattern formation. This study reports the results of an ultrastructural comparison of pollen wall formation in the mutant to wall development in wild-type plants. Pollen wall development in the mutant parallels that of wild-type until the early tetrad stage. At this point in wild-type plants, the microspore plasma membrane assumes a regular pattern of ridges and valleys. Initial sporopollenin deposition occurs on the ridges marking the beginning of probacula formation. In contrast, the plasma membrane in the mutant appears irregular with flattened protuberances and rare invaginations. As a result, the wild-type regular pattern of ridges and valleys is not formed. Sporopollenin is randomly deposited on the plasma membrane and aggregates on the locule wall; it is not anchored to the membrane. Our finding that the mutation blocks the normal invagination of the plasma membrane and disrupts the proper deposition of sporopollenin during wall formation suggests that the mutation could be in a gene responsible for pattern formation. These results also provide direct evidence that the plasma membrane plays a critical role in the establishment of the pollen wall pattern. 相似文献
9.
Peter?BlokkerEmail author Peter?Boelen Rob?Broekman Jelte?Rozema 《Plant Ecology》2006,182(1-2):197-207
The applicability of p-coumaric acid and ferulic acid concentrations or ratios in (sub)fossil plant remnant as UV-B proxies relies on various aspects,
which are discussed in this paper and will be illustrated with some experimental data. A newly developed THM-micropyrolysis–gas
chromatography–mass spectrometry method was tested on various spores, pollen and other plant remains, which were analysed
for the presence of the UV-absorbing compounds p-coumaric acid and ferulic acid. This revealed that these supposed building-blocks of sporopollenin appear to be present in
pollen of many plant species but also in moss spores. The development of this micropyrolysis method paved the way for the
quantitative analysis of UV-absorbing compounds in case only a small amount of analyte is available, for example for fossil
pollen and spores but also other small palynomorphs and plant fossils. The use of this technique will provide a better insight
in the plant responses to UV-radiation, the chemistry of pollen and spores, their fossil counterparts and furthermore the
means for a further development of a proxy for the reconstruction of past UV-B radiation. 相似文献
10.
Peter Blokker Stefan Schouten Jan W. de Leeuw Jaap S. Sinninghe Damsté Herman van den Ende 《Planta》1999,207(4):539-543
The unicellular green alga Chlamydomonas monoica Strehlow is known to produce zygospores with a cell wall that is resistant against microbial and chemical attack. This resistance
is thought to be due to the presence of a sporopollenin-like material. However, the resistant nature of sporopollenin-like
materials seriously hampers their structural analysis. With complementary techniques such as 13C-nuclear magnetic resonance spectroscopy, Curie-point pyrolysis-gas chromatography/mass spectroscopy and RuO4 chemical degradation, the chemical composition of resistant biopolymer in the isolated cell walls of C. monoica zygospores was determined. This material is composed of C22–C30 linear alcohols and carboxylic acids, intermolecularly linked via ester and ether-linkages similar to the resistant aliphatic
biopolymers encountered in the walls of the vegetative cells of the algae Tetraedron minimum, Scenedesmus communis and Pediastrum boryanum.
Received: 29 April 1998 / Accepted: 2 October 1998 相似文献