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1.
Spatial regulation of pectic polysaccharides in relation to pit fields in cell walls of tomato fruit pericarp
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Scanning electron microscopic examination of intact tomato (Lycopersicon esculentum) pericarp and isolated pericarp cell walls revealed pit fields and associated radiating ridges on the inner face of cell walls. In regions of the cell wall away from pit fields, equivalent ridges occurred in parallel arrays. Treatment of isolated cell walls with a calcium chelator resulted in the loss of these ridges, indicating that they contain homogalacturonan-rich pectic polysaccharides. Immunolabeling procedures confirmed that pit fields and associated radiating ridges contained homogalacturonan. Epitopes of the side chains of pectic polysaccharides were not located in the same regions as homogalacturonan and were spatially regulated in relation to pit fields. A (1-->4)-beta-galactan epitope was absent from cell walls in regions of pit fields. A (1-->5)-alpha-arabinan epitope occurred most abundantly at the inner face of cell walls in regions surrounding the pit fields. 相似文献
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Hayashi Ryuzo; Morikawa Hiromichi; Nakajima Norihiko; Ichikawa Yoshiaki; Senda Mitsugi 《Plant & cell physiology》1980,21(6):999-1005
Polarized infrared absorption spectra of film specimens of theepidermal cell wall of the third internode of pea stems wererecorded before and after treatment with endopolygalacturonase(endo-PG) and endo-pectin lyase (endo-PL). The spectra showedthat the pectic polysaccharides solubilized with endo-PG wereessentially the same as those solubilized with endo-PL. Thedegree of esterification of the pectic polysaccharides was about20%, and their major sugar components were uronic acids (32.8%),arabinose (48.1%) and galactose (19.2%). The polarized infraredspectra showed that pectic polysaccharides have an orientedstructure in cell walls with their molecular chains orientedpreferentially parallel to the direction of cell elongation.
1Present address: Research and Development, Kanzaki Paper Mfg.Co., Ltd., Amagasaki, Hyogo 660, Japan.
2Present address: Wakayama Research Laboratories, Kao Soap Co.,Ltd., Wakayama 640-91, Japan. (Received June 28, 1980; ) 相似文献
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The occurrence of pectic polysaccharide epitopes in cells and tissues of the pea testa during late stages of seed development have been examined in relation to anatomy and cell properties. Homogalacturonan, in a highly methyl-esterified form, was present throughout late development in all pea testa cell walls, including the thickened cell walls of the outer macrosclereid layer. Two epitopes, characteristic of the side-chains of the rhamnogalacturonan-I domain of pectic polysaccharides, occurred in restricted and separate cell layers of the pea testa. A (1-->4)-beta-D-galactan epitope was restricted to regions of the outer cell wall of the testa and to inner regions of the macrosclereid layer at 20 DAA and was absent from the osteosclereid and parenchyma cell walls. By 25 DAA the (1-->4)-beta-D-galactan epitope occurred only in the outer epidermal cell walls. A (1-->5)-alpha-L-arabinan epitope was also dependent on the developmental stage of the seed and was found with greatest abundance in the walls of the inner parenchyma cells. Cell separation studies indicated that, although calcium cross-links were involved in the maintenance of the link between the macrosclereid layer and proximal cell layers, most cell-to-cell adhesion in the testa was not due to calcium- or ester-based bonds. 相似文献
6.
Kerry Hosmer Caffall 《Carbohydrate research》2009,344(14):1879-1900
Plant cell walls consist of carbohydrate, protein, and aromatic compounds and are essential to the proper growth and development of plants. The carbohydrate components make up ∼90% of the primary wall, and are critical to wall function. There is a diversity of polysaccharides that make up the wall and that are classified as one of three types: cellulose, hemicellulose, or pectin. The pectins, which are most abundant in the plant primary cell walls and the middle lamellae, are a class of molecules defined by the presence of galacturonic acid. The pectic polysaccharides include the galacturonans (homogalacturonan, substituted galacturonans, and RG-II) and rhamnogalacturonan-I. Galacturonans have a backbone that consists of α-1,4-linked galacturonic acid. The identification of glycosyltransferases involved in pectin synthesis is essential to the study of cell wall function in plant growth and development and for maximizing the value and use of plant polysaccharides in industry and human health. A detailed synopsis of the existing literature on pectin structure, function, and biosynthesis is presented. 相似文献
7.
The types of binding of different mono- and divalent ions to sites of the
constitutive pectic acids of the Nitella cell walls
were investigated by performing ion exchanges at different pH. The
experimental results were then analysed in the framework of a model derived
from the polyelectrolyte theory in which the competitive process of
dissociation of the exchange sites and their complexation by counterions
are taken into account. Divalent ions Ca2+ and
Mn2+ interacted specifically with the exchange sites
to give rise to strong thermodynamic association constants. They also
induced conformational transitions of the pectic acids which allowed some
site-specific association with monovalent ions, although the latter, in the
absence of divalent ions, interacted only in a purely electrostatic manner
with the charged sites. The complexation phenomenon of the monovalent ions
also results in a feedback process which enhances or depletes the
site-specific interactions of the divalent counterions. Changes in the
counterion association with the wall exchange sites will take place without
modification in the wall electrostatic field, when divalent ions are
present at the usual pH. These specific interactions are supported by the
values of the residual interaction energy, calculated from the variations
of the apparent pKa of the polygalacturonic acids with
their degree of protonation. 相似文献
8.
Carrot (Daucus carota L.) embryogenic callus (EC) loses its embryogenic competence and becomes nonembryogenic callus (NC) during long-term culture. With the loss of embryogenic competence, the cell clusters become smaller and the extent of intercellular attachments is reduced. Pectic fractions prepared from EC and NC were separated into two subfractions by gel filtration. A difference in sugar composition between EC and NC was found only in the high-molecular-mass (ca. 1300 kDa) subfraction, and the ratio of the amount of arabinose to that of galactose (Ara/Gal) was strongly and positively correlated with the size of cell clusters in several different cultures. From the results of sugar-composition and methylation analyses, and the results of treatment with exo-arabinanase, models of the neutral sugar chains of pectins from EC and NC are proposed. Both neutral sugar chains are composed of three regions. The basal region is composed of linearly linked arabinan 5-Araf> moieties in both types of callus. The middle galactan region is composed of 6-linked galactose, some of which branches at the 3 and 4 positions, and this region is larger and more frequently branched in NC than in EC. Finally, the terminal arabinan region is composed of 5-linked arabinose, branched at the 3 position, and the size of the terminal arabinan is larger in EC than in NC. The significance of the neutral sugar chains of pectins in the interaction of cell wall components and intercellular attachment is discussed.Abbreviations Ara/Gal
ratio (w/w) of the amount of arabinose to that of galactose
- EC
embryogenic callus
- NC
non-embryogenic callus
- T-Araf
terminal arabinose
The authors are grateful to Dr. Naoto Shibuya of the National Institute of Agrobiological Resources for his gift of exo-arabinanase. 相似文献
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Transmembrane helices from crystallographically determined structures were analyzed to determine the distribution of side chains inside and outside helix-helix interfaces. Two structural characteristics were explored: (1) the number of atoms outside the interfaces that belong to the side chains with the C(alpha) atoms inside the interfaces, as well as the opposite, inside/outside number (conformation-dependent values) and (2) the side-chain length (depends only on the residue type and does not depend on the side-chain conformation). The results showed that the interface side chains tend to be bent away from the interacting helix. The most important finding, however, is that the side chains in the interface areas, on average, are shorter than in the noninterface areas. Proteins 2000;40:429-435. 相似文献
11.
Boron and calcium, essential inorganic constituents of pectic polysaccharides in higher plant cell walls 总被引:11,自引:0,他引:11
Among 16 essential elements of higher plants, Ca2+ and B have been termed as apoplastic elements. This is mainly because of their localization in cell walls, however, it has
turned to be highly likely that these two elements significantly contribute to maintain the integrity of cell walls through
binding to pectic polysaccharides.
Boron in cell walls exclusively forms a complex with rhamnogalacturonan II (RG-II), and the B-RG-II complex is ubiquitous
in higher plants. Analysis of the structure of the B-RG-II complex revealed that the complex contains two molecules boric
acid, two molecules Ca2+ and two chains of monomeric RG-II. This result indicates that pectic chains are cross-linked covalently with boric acid at
their RG-II regions. The complex was reconstitutedin vitro only by mixing monomeric RG-II and boric acid, however, the complex decomposed spontaneously unless Ca2+ was supplemented. Furthermore, the native complex decomposed when it was incubated withtrans-1,2-diaminocyclohexane-N, N, N′, N′-tetraacetic acid (CDTA) which chelates Ca2+.
When radish root cell walls were washed with a buffered 1.5% (w/v) sodium dodesyl sulfate (SDS) solution (pH 6.5), 96%, 13%
and 6% of Ca2+, B and pectic polysaccharides of the cell walls, respectively, were released and the cell wall swelled twice. Subsequent
extraction with 50 mM CDTA (pH 6.5) of the SDS-washed cell walls further released 4%, 80% and 61% of Ca2+, B and pectic polysaccharides, respectively. Pectinase hydrolysis of the SDS-treated cell walls yielded a B-RG-II complex
and almost all the remaining Ca2+ was recovered in the complex. This result suggests that cell-wall bound Ca2+ is divided into at least two fractions, one anchors the CDTA-soluble pectic polysaccharides into cell walls together with
B, and the other may control the properties of the pectic gel.
These studies demonstrate that B functions to retain CDTA-soluble pectic polysaccharides in cell walls through its binding
to the RG-II regions in collaboration with Ca2+. 相似文献
12.
Jens Øbro Bernhard Borkhardt Jesper Harholt Michael Skjøt William G. T. Willats Peter Ulvskov 《Transgenic research》2009,18(6):961-969
Despite the wide occurrence of pectin in nature only a few source materials have been used to produce commercial pectins.
One of the reasons for this is that many plant species contain pectins with high levels of neutral sugar side chains or that
are highly substituted with acetyl or other groups. These modifications often prevent gelation, which has been a major functional
requirement of commercial pectins until recently. We have previously shown that modification of pectin is possible through
heterologous expression of pectin degrading enzymes in planta. To test the effect of simultaneous modification of the two main neutral pectic side chains in pectic rhamnogalacturonan
I (RGI), we constitutively expressed two different enzymes in Arabidopsis thaliana that would either modify the galactan or the arabinan side chains, or both side chains simultaneously. Our analysis showed
that the simultaneous truncation of arabinan and galactan side chains is achievable and does not severely affect the growth
of Arabidopsis thaliana. 相似文献
13.
The relation between cell proliferation,differentiation and ultrastructural development in rat intestinal epithelium 总被引:4,自引:0,他引:4
Dr. J. M. van Dongen W. J. Visser W. Th. Daems H. Galjaard 《Cell and tissue research》1976,174(2):183-199
Summary The ultrastructural development of the principal cells in rat small intestine was studied by morphometric analyses in relation to the exact cell position along crypt and villus. From the bottom to the tip of the crypt, a gradual increase occurred in absolute size of the total cell, the cytoplasm, the terminal web and of nearly all cell organelles. Also, the relative size of the cytoplasm, mitochondria, microvilli and endoplasmic reticulum increased during crypt cell differentiation. No sudden changes in ultrastructure were observed in the so-called critical decision zone, normally located halfway up the crypt where the proliferative activity ceases. At the crypt-villous junction a 1.4–3 fold increase in cell size, cytoplasm, terminal web and of most organelles was noted. Expansion of the proliferative cell compartment over the total length of the crypt as occurs during recovery after a low X-irradiation dose (72 h after 400 R) does not affect the normal development of cellular ultrastructure. These findings are discussed in relation to biochemical and cell kinetic data. 相似文献
14.
Cláudia NunesLisete Silva Ana P. FernandesRaquel P.F. Guiné M. Rosário M. DominguesManuel A. Coimbra 《Carbohydrate polymers》2012,87(1):620-626
The study carried out in this work concerns the structural characterization of pectic polysaccharides from plum (Prunus domestica L.) and pear (Pyrus communis L.) cell walls and commercial pectic polysaccharides, obtained from Citrus. The α-(1 → 4)-d-galacturonic acid backbone was submitted to a selective hydrolysis with endo-polygalacturonase (EPG) and the fractions with low molecular weight (<1 kDa) obtained by size-exclusion chromatography were analysed by mass spectrometry using electrospray ionisation (ESI-MS). The ESI-MS spectra obtained revealed the presence of several [M+Na]+ ions of pectic oligosaccharides identified as belonging to different series, including oligosaccharides constituted only by galacturonic acid residues (GalAn, n = 1-5) and galacturonic acid residues substituted by pentose residues (GalA3Pentn, n = 1-2). Surprisingly, it was also observed the occurrence of galacturonic acid residues substituted by hexose residues (GalAnHexm, n = 2-4, m = 1-2). The fragmentation of the observed [M+Na]+ ions, obtained under ESI-MS/MS and MSn allowed to confirm the proposed structures constituent of these pectic oligosaccharides. Furthermore, the ESI-MSn spectra of the ions that could be identified as GalAnHexm (n = 2-4, m = 1-2) confirmed the presence of Hex or Hex2 residues linked to a GalA residue. Methylation analysis showed the presence, in all EPG treated samples, of terminally linked arabinose, terminally and 4-linked xylose, and terminally and 4-linked glucose. The occurrence of GalA substituted by Glc, and Glc-β-(1 → 4)-Glc are structural features that, as far as we know, have never been reported to occur in pectic polysaccharides. 相似文献
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Coordinating cell proliferation and differentiation 总被引:15,自引:0,他引:15
Cell proliferation and differentiation are highly coordinated processes during development. Recent studies have revealed that this coordination may result from dual functions residing in the central regulators of proliferation, allowing them to also regulate differentiation. Studies have also shown that some terminally differentiated cells can be made to divide beyond their normal capacity. 相似文献
17.
Summary Cell walls and media were obtained from three kinds of carrot cell culture, namely, embryogenic callus (EC), non-embryogenic callus (NC) and somatic embryos (SE), and analyzed for their sugar content and sugar composition by electrophoresis and gas chromatography. EC formed large cell clusters while NC formed small clusters. Observations under the light microscope revealed that the intercellular contacts in NC were much more limited than those in EC. The analysis of pectic polysaccharides revealed that the level of neutral sugars was higher than that of acidic sugars in EC, while the opposite was true in NC. Gaschromatographic analysis of neutral sugars in pectic fractions revealed that EC and SE were rich in arabinose, while NC was rich in galactose. On the basis of these results, we discuss the possible involvement of neutral sugars, and of arabinose and galactose in particular, in pectic polysaccharides in intercellular contacts.Abbreviations EC
embryogenic callus
- NC
non-embryogenic callus
- SE
somatic embryo
- MS
Murashige and Skoog
- PAS
periodic acid-Schiff s reagent 相似文献
18.
Haruyoshi Konno Susumu Nakashima Toshihiko Maitani Kenji Katoh 《Physiologia plantarum》1999,107(3):287-293
Suspension-cultured carrot ( Daucus carota L. cv. Kintoki) cells were grown in calcium (Ca2+ )-deficient and normal liquid media. Cell growth was limited by the Ca2+ deficiency. Similar amounts of pectic fractions were extracted from the walls of control and Ca2+ -deprived cells, but the fractions from the walls of Ca2+ -deprived cells showed a substantial decrease in galacturonic acid content. However, after 15 days of culture, Ca2+ -deprived cells released galacturonic acid-rich extracellular polysaccharides at twice the rate of control cells. The polysaccharides consisted of a mixture of several polymers containing predominantly arabinose, galactose and galacturonic acid. Ca2+ -deprived cells also secreted three times more extracellular proteins, containing many glycan-hydrolytic enzymes, into the medium than did normal cells. SDS-PAGE analysis revealed several distinct changes in the polypeptide pattern in the medium of control and Ca2+ -deprived cells. Activities of α -galactosidase, β -glucosidase and exo- polygalacturonase increased considerably during Ca2+ deficiency, whereas α - l -arabinofuranosidase and β -galactosidase activities were much reduced. 相似文献
19.
Galactose loss and fruit ripening: high-molecular-weight arabinogalactans in the pectic polysaccharides of fruit cell walls 总被引:7,自引:0,他引:7
Cell wall material (CWM) was prepared from nine fruit species at two ripening stages (unripe and ripe) and extracted sequentially
with 0.05 M trans-1,2-diaminocyclohexane-N,N,N′,N′-tetraacetic acid (CDTA), 0.05 M Na2CO3 and 4 M KOH. Each solubilised fraction and the CWM-residue remaining after 4 M KOH extraction was analysed for non-cellulosic
sugar composition. A common pattern of distribution for polyuronide and pectin-associated neutral sugar was observed for all
unripe fruit. Most polyuronide was extracted in the CDTA/Na2CO3 fractions while 70–93% of the neutral sugar was located on pectic polysaccharides in the 4 M KOH-soluble and CWM-residue
fractions. During ripening, most of the galactose was lost from pectic polysaccharides in the CWM-residue. Partial solubilisation
of these polysaccharides was achieved by treating the CWM-residue with endopolygalacturonase. The solubilised polysaccharides
were separated into two fractions by ion-exchange chromatography. One of these contained polysaccharides with average molecular
weights of 400 kDa or larger and consisted of between 70 and 90% arabinogalactan. The galactosyl residues were 80–90% β-1→4
linked, indicating largely unbranched side-chains. The arabinosyl residues were distributed among terminal, 3-, 5-, 2,5-,
and 2,3,5-linked residues, indicating a highly ramified structure. The results are discussed with regard to the relationship
between pectin solubilisation and galactose loss and their respective contribution to fruit softening.
Received: 28 January 1997 / Accepted: 11 March 1997 相似文献
20.
When leaf disks from haploid plants of Nicotiana plumbaginifolia Viv. were transformed with T-DNA and cultured on shoot-inducing medium, nonorganogenic callus. designated nolac (for non-organogenic callus with loosely attached cells), appeared on approximately 7% of leaf disks. In contrast, normal callus was generated on T-DNA-transformed leaf disks from diploid plants and on non-transformed leaf disks from haploid and diploid plants. Transmission electron microscopy revealed that the middle lamellae and the cell walls of one line of mutant callus (nolac-H14) were barely stained by ruthenium red. even after demethylesterification with NaOH, whereas the entire cell wall and the middle lamella were strongly stained in normal callus. In cultures of nolac-H14 callus, the level of sugar components of pectic polysaccharides in the hemicellulose fraction was reduced and that in the culture medium was elevated, as compared with cultures of normal callus. These results indicate that pectic polysaccharides are not retained in the cell walls and middle lamellae of nolac-H14 callus. In nolac-H14, the ratio of arabinose to galactose was low in the pectic polysaccharides purified from all cell wall fractions and from the medium, in particular, in the hemicellulose fractions. The low levels of arabinofuranosyl (T-Araf, 5-Araf, 2,5-Araf, and 3,5-Araf) residues in the pectic polysaccharides of the hemicellulosic fraction of nolac-H,14 indicated that no neutral-sugar side chains, composed mainly of linear arabinan. were present in nolac-H14. Arabinose-rich pectins. which are strongly associated with cellulose-hemicellulose complexes, might play an important role in intercellular attachment in the architecture of the cell wall. 相似文献