Статті в журналах: "Cell wall degradation"

1

Singh, Adya P., Yoon Soo Kim, and Ramesh R. Chavan. "Relationship of wood cell wall ultrastructure to bacterial degradation of wood." IAWA Journal 40, no. 4 (November 16, 2019): 845–70. http://dx.doi.org/10.1163/22941932-40190250.

Повний текст джерела

Анотація:

ABSTRACT This review presents information on the relationship of ultrastructure and composition of wood cell walls, in order to understand how wood degrading bacteria utilise cell wall components for their nutrition. A brief outline of the structure and composition of plant cell walls and the degradation patterns associated with bacterial degradation of wood cell walls precedes the description of the relationship of cell wall micro- and ultrastructure to bacterial degradation of the cell wall. The main topics covered are cell wall structure and composition, patterns of cell wall degradation by erosion and tunnelling bacteria, and the relationship of cell wall ultrastructure and composition to wood degradation by erosion and tunnelling bacteria. Finally, pertinent information from select recent studies employing molecular approaches to identify bacteria which can degrade lignin and other wood cell wall components is presented, and prospects for future investigations on wood degrading bacteria are explored.

Стилі APA, Harvard, Vancouver, ISO та ін.

2

Imam, S. H., M. J. Buchanan, H. C. Shin, and W. J. Snell. "The Chlamydomonas cell wall: characterization of the wall framework." Journal of Cell Biology 101, no. 4 (October 1, 1985): 1599–607. http://dx.doi.org/10.1083/jcb.101.4.1599.

Повний текст джерела

Анотація:

The cell wall of the biflagellate alga Chlamydomonas reinhardtii is a multilayered, extracellular matrix composed of carbohydrates and 20-25 polypeptides. To learn more about the forces responsible for the integrity of this cellulose-deficient cell wall, we have begun studies to identify and characterize the framework of the wall and to determine the effects of the cell wall-degrading enzyme, lysin, on framework structure and protein composition. In these studies we used walls released into the medium by mating gametes. When isolated shed walls are degraded by exogenously added lysin, no changes are detected in the charge or molecular weight of the 20-25 wall proteins and glycoproteins when analyzed on one- and two-dimensional polyacrylamide gels, which suggests that degradation of these shed walls is due either to cleavage of peptide bonds very near the ends of polypeptides or that degradation occurs via a mechanism other than proteolysis. Incubation of walls with Sarkosyl-urea solutions removes most of the proteins and yields thin structures that appear to be the frameworks of the walls. Analysis by polyacrylamide gel electrophoresis shows that the frameworks are highly enriched in a polypeptide of Mr 100,000. Treatment of frameworks with lysin leads to their degradation, which indicates that this part of the wall is a substrate for the enzyme. Although lysin converts the Mr 100,000 polypeptide from an insoluble to a soluble form, there is no detectable change in Mr of the framework protein. Solubilization in the absence of lysin requires treatment with SDS and dithiothreitol at 100 degrees C. These results suggest that the Chlamydomonas cell wall is composed of two separate domains: one containing approximately 20 proteins held together by noncovalent interactions and a second domain, containing only a few proteins, which constitutes the framework of the wall. The result that shed walls can be solubilized by boiling in SDS-dithiothreitol indicates that disulfide linkages are critical for wall integrity. Using an alternative method for isolating walls from mechanically disrupted gametes, we have also shown that a wall-shaped portion of these unshed walls is insoluble under the same conditions in which shed walls are soluble. One interpretation of these results is that wall release during mating and the wall degradation that follows may involve distinct biochemical events.

Стилі APA, Harvard, Vancouver, ISO та ін.

3

Mravec, Jozef. "Border cell release: Cell separation without cell wall degradation?" Plant Signaling & Behavior 12, no. 7 (July 3, 2017): e1343778. http://dx.doi.org/10.1080/15592324.2017.1343778.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

4

Batisse, C., P. J. Coulomb, C. Coulomb, and M. Buret. "Ultrastructure des parois de cerises Bigarreau Burlat de textures différentes au cours de la maturation." Canadian Journal of Botany 74, no. 12 (December 1, 1996): 1974–81. http://dx.doi.org/10.1139/b96-236.

Повний текст джерела

Анотація:

The changes in texture of fruits during ripening are linked to cell wall degradation involving synthesis and degradation of polymers. An increase in pectin solubility leads to cell sliding and an elastic aspect of tissues. The biochemical cell wall process differs between soft and crisp fruits originating from a same cultivar but cultivated under different agroclimatic conditions. Although the proportions of cell wall material are similar, the composition and structure of the two cell walls are very different at maturity. A solubilization of the middle lamella and a restructuration of the primary cell walls arising from the cells separation is observed in crisp fruits. In contrast, the middle lamella of the soft fruits is better preserved and the primary cell walls are thin and show degradation bags delimited by residual membrane formations. In addition, the macroendocytosis process by endosome individualization is more important in soft fruits. In conclusion, the fruit texture depends on the extent of the links between cell wall polymers. Keywords: cherry, cell wall, texture, ultrastructural study.

Стилі APA, Harvard, Vancouver, ISO та ін.

5

Singh, Adya P., Shruti Singh, and Ehsan Bari. "Bacterial Degradation of Wood by Tunnel Formation: Role of TEM in Understanding the Intricate Architecture of Tunnels and the Cell Wall Degradation Process." Microscopy Today 30, no. 5 (September 2022): 24–30. http://dx.doi.org/10.1017/s1551929522001080.

Повний текст джерела

Анотація:

Abstract:Certain bacteria degrade wood by creating tunnels in cell walls. Transmission electron microscopy (TEM) has played a key role in understanding the intricate architecture of the tunnels produced within the cell wall and the process of cell wall degradation. The most prominent feature of tunnels is the presence of periodic crescent-shaped slime bands, which is the single most important diagnostic characteristic of bacterial tunneling-type cell wall degradation. The review presented covers the aspects relevant to understanding bacterial tunneling of wood cell walls, emphasizing the importance of the application of TEM in this area of research.

Стилі APA, Harvard, Vancouver, ISO та ін.

6

Tsuneda, A., and R. G. Thorn. "Interactions of wood decay fungi with other microorganisms, with emphasis on the degradation of cell walls." Canadian Journal of Botany 73, S1 (December 31, 1995): 1325–33. http://dx.doi.org/10.1139/b95-394.

Повний текст джерела

Анотація:

Interactions of two wood decay fungi, Lentinula edodes and Pleurotus ostreatus, with other wood inhabiting microorganisms were investigated on agar and in fagaceous wood, primarily by scanning electron microscopy. Micromorphologically, there were two principal modes of cell wall degradation: (i) selective removal of amorphous wall components, followed by the degradation of skeletal microfibrils, and (ii) simultaneous degradation of all wall components. These two modes were observed in three different degradation systems: (i) sapwood wall degradation by the wood decay fungi, (ii) hyphal wall degradation by mycoparasitic Trichoderma, and (iii) hyphal wall degradation by pathogenic bacteria. The simultaneous-type wall degradation in the systems i and ii was usually caused by hyphal tips. In addition to the three systems, bacteriolysis by the wood decay fungi was also studied. The bacterial cell walls, as well as microfibril bundles of wood cellulose and fungal chitin, were all fragmented into minute granules at later stages of microbial degradation and the granules were further degraded into smaller units. Frequency of occurrence and strength of mycoparasitic activity of Trichoderma harzianum were influenced by the degree of wood decay where the interaction occurred. Presence of both cellulose and chitin microfibrils apparently enhanced the mycoparasitic activity. In Quercus wood, P. ostreatus showed a unidirectional growth toward bacterial colonies, which formed as the result of decomposition of dead nematodes, and consumed the unidentified bacteria. In nitrogen-deficient wood, fungal and bacterial cell walls may serve as an important reservoir of nitrogen for wood inhabiting microorganisms. Key words: wood decay, mycoparasitism, bacteriolysis, cellulose, chitin.

Стилі APA, Harvard, Vancouver, ISO та ін.

7

Murashima, Koichiro, Akihiko Kosugi, and Roy H. Doi. "Synergistic Effects of Cellulosomal Xylanase and Cellulases from Clostridium cellulovorans on Plant Cell Wall Degradation." Journal of Bacteriology 185, no. 5 (March 1, 2003): 1518–24. http://dx.doi.org/10.1128/jb.185.5.1518-1524.2003.

Повний текст джерела

Анотація:

ABSTRACT Plant cell walls are comprised of cellulose and hemicellulose and other polymers that are intertwined, and this complex structure presents a barrier to degradation by pure cellulases or hemicellulases. In this study, we determined the synergistic effects on corn cell wall degradation by the action of cellulosomal xylanase XynA and cellulosomal cellulases from Clostridium cellulovorans. XynA minicellulosomes and cellulase minicellulosomes were found to degrade corn cell walls synergistically but not purified substrates such as xylan and crystalline cellulose. The mixture of XynA and cellulases at a molar ratio of 1:2 showed the highest synergistic effect of 1.6 on corn cell wall degradation. The amounts both of xylooligosaccharides and cellooligosaccharides liberated from corn cell walls were increased by the synergistic action of XynA and cellulases. Although synergistic effects on corn cell wall degradation were found in simultaneous reactions with XynA and cellulases, no synergistic effects were observed in sequential reactions. The possible mechanism of synergism between XynA and cellulases is discussed.

Стилі APA, Harvard, Vancouver, ISO та ін.

8

Campion, C., B. Vian, M. Nicole, and F. Rouxel. "A comparative study of carrot root tissue colonization and cell wall degradation by Pythium violae and Pythium ultimum, two pathogens responsible for cavity spot." Canadian Journal of Microbiology 44, no. 3 (March 1, 1998): 221–30. http://dx.doi.org/10.1139/w97-157.

Повний текст джерела

Анотація:

The process of infection of carrots by Pythium violae and Pythium ultimum, two causes of cavity spot, is described. The first species causes limited root necrosis, the second progressive root rot. Colonization by both species was intracellular and limited within the tissues. Modes of cell wall degradation were studied by staining (PATAg test) and labeling techniques. Pectins were labeled with monoclonal antibodies and cellulose with an exoglucanase-gold complex. Cell wall polysaccharides were degraded differently by the two species. Pythium violae was responsible for degradations, which could be noticeable, especially for high methylesterified pectins, but which occurred after colonization and were localized near the hyphae. The conservation of integrity of diseased tissue was apparently due to the absence of degradation away from the hyphae. In contrast, P. ultimum was responsible for more extensive degradation of pectins and cellulose, which occurred at a relatively greater distance from the hyphae. Degradation of pectins was always more rapid in the cell walls than in the intercellular junctions. This phenomenon led to loss of tissue integrity and could explain the tissue maceration caused by P. ultimum infection. These differences in infection process are discussed in connection with the enzymic potential for degradation of cell wall polysaccharides.Key words: Daucus carota L., Pythium, pectin, cellulose, cytochemistry.

Стилі APA, Harvard, Vancouver, ISO та ін.

9

Encinas, Osvaldo, and Geoffrey Daniel. "Degradation of the Gelatinous Layer in Aspen and Rubberwood by the Blue Stain Fungus Lasiodiplodia Theobromae." IAWA Journal 18, no. 2 (1997): 107–15. http://dx.doi.org/10.1163/22941932-90001471.

Повний текст джерела

Анотація:

Studies on the degradative ability of the blue stain fungus Lasiodiplodia theobromae (Pat.) Griffon ' Maublanc have shown several strains to cause significant weight losses (c. 20%) in wood of temperate and tropical species, aspen (Populus tremula) and rubberwood (Hevea brasiliensis), both species that commonly form tension wood. In addition to the consumption of soluble carbohydrates, major changes occurred in the ultrastructure of fibre cell walls, with a rapid attack of the G-layer of the gelatinous fibres. Following G-layer degradation, earlywood fibres of both species showed true cell wall degradation with pronounced erosion attack, suggesting that prior destruction of the G-layer afforded greater accessibility and ease of attack of the outer secondary cell wall layers.

Стилі APA, Harvard, Vancouver, ISO та ін.

10

El-Assi, N., D. J. Huber, and J. K. Brecht. "Cell Wall Degradation in Irradiated Tomato Fruit." HortScience 30, no. 4 (July 1995): 815B—815. http://dx.doi.org/10.21273/hortsci.30.4.815b.

Повний текст джерела

Анотація:

The irradiation of harvested fruit is typically accompanied by excessive tissue softening, a process that is not well understood. In this study, we examined the role of specific cell wall polymers and the extent of general cell wall degradation and softening in irradiated tomato fruit. `Sunny' tomato fruit at mature-green and pink stages were subjected to X-ray radiation at 0, 83, and 156 Krad. Immediate softening was noted for both maturation classes, although some postirradiation recovery was evident in green fruit. Pectic polymers of both mature-green and pink fruit exhibited depolymerization and altered neutral sugar profiles in response to irradiation. Pectins, either as components of total ethanol-insoluble solids (EIS), purified by selective extraction, or of commercial origin were similarly affected by irradiation. Cellulose preparations were unaffected by irradiation. The data demonstrate that the effect of irradiation on the cell wall exhibits specificity, can occur nonenzymatically, and does not require initiating adducts of cytosolic origin.

Стилі APA, Harvard, Vancouver, ISO та ін.

11

Tucker, G. A., and G. B. Seymour. "CELL WALL DEGRADATION DURING MANGO FRUIT RIPENING." Acta Horticulturae, no. 291 (June 1991): 454–60. http://dx.doi.org/10.17660/actahortic.1991.291.51.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

12

Wei, Hui, Qi Xu, Larry E. Taylor, John O. Baker, Melvin P. Tucker, and Shi-You Ding. "Natural paradigms of plant cell wall degradation." Current Opinion in Biotechnology 20, no. 3 (June 2009): 330–38. http://dx.doi.org/10.1016/j.copbio.2009.05.008.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

13

Buckeridge, Marcos Silveira. "Seed Cell Wall Storage Polysaccharides: Models to Understand Cell Wall Biosynthesis and Degradation." Plant Physiology 154, no. 3 (September 20, 2010): 1017–23. http://dx.doi.org/10.1104/pp.110.158642.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

14

Brunner, Ueli, and Rosmarie Honegger. "Chemical and ultrastructural studies on the distribution of sporopolleninlike biopolymers in six genera of lichen phycobionts." Canadian Journal of Botany 63, no. 12 (December 1, 1985): 2221–30. http://dx.doi.org/10.1139/b85-315.

Повний текст джерела

Анотація:

Cell walls of cultured lichen phycobionts of the genera Coccomyxa, Elliptochloris, Myrmecia, Pseudochlorella, Trebouxia, and Trentepohlia were investigated with cytological and chemical methods with regard to the presence or absence of trilaminar sheaths and (or) resistant biopolymers. Trilaminar cell wall layers occurred in Coccomyxa, Elliptochloris, Myrmecia, and (less distinctly) Pseudochlorella species. A biopolymer highly resistant to nonoxidative degradation by phosphoric acid occurred only in the isolated and vigorously extracted cell walls of Coccomyxa and Elliptochloris species. The walls of all the other phycobionts, including Myrmecia and Pseudochlorella, were totally degraded, showing that a trilaminar wall layer is not conclusive evidence for the presence of a resistant cell wall polymer. The infrared absorption spectra of the degradation-resistant cell wall polymer of Coccomyxa and Elliptochloris species were not fully identical with those of natural sporopollenins. When the widely used, but chemically less appropriate acetolysis method was applied to either entire cells or isolated but not fully extracted cell walls of Coccomyxa, Elliptochloris, Myrmecia, Pseudochlorella, Trebouxia, and Trentepohlia species, they all yielded acetolysis-resistant residues whose infrared spectra resembled natural sporopollenin.

Стилі APA, Harvard, Vancouver, ISO та ін.

15

Šimelyte, Egle, Marja Rimpiläinen, Leena Lehtonen, Xiang Zhang, and Paavo Toivanen. "Bacterial Cell Wall-Induced Arthritis: Chemical Composition and Tissue Distribution of Four Lactobacillus Strains." Infection and Immunity 68, no. 6 (June 1, 2000): 3535–40. http://dx.doi.org/10.1128/iai.68.6.3535-3540.2000.

Повний текст джерела

Анотація:

ABSTRACT To study what determines the arthritogenicity of bacterial cell walls, cell wall-induced arthritis in the rat was applied, using four strains of Lactobacillus. Three of the strains used proved to induce chronic arthritis in the rat; all were Lactobacillus casei. The cell wall of Lactobacillus fermentum did not induce chronic arthritis. All arthritogenic bacterial cell walls had the same peptidoglycan structure, whereas that of L. fermentum was different. Likewise, all arthritogenic cell walls were resistant to lysozyme degradation, whereas the L. fermentum cell wall was lysozyme sensitive. Muramic acid was observed in the liver, spleen, and lymph nodes in considerably larger amounts after injection of an arthritogenicL. casei cell wall than following injection of a nonarthritogenic L. fermentum cell wall. The L. casei cell wall also persisted in the tissues longer than theL. fermentum cell wall. The present results, taken together with those published previously, underline the possibility that the chemical structure of peptidoglycan is important in determining the arthritogenicity of the bacterial cell wall.

Стилі APA, Harvard, Vancouver, ISO та ін.

16

Lee, S. S., J. K. Ha, and K. J. Cheng. "Relative Contributions of Bacteria, Protozoa, and Fungi to In Vitro Degradation of Orchard Grass Cell Walls and Their Interactions." Applied and Environmental Microbiology 66, no. 9 (September 1, 2000): 3807–13. http://dx.doi.org/10.1128/aem.66.9.3807-3813.2000.

Повний текст джерела

Анотація:

ABSTRACT To assess the relative contributions of microbial groups (bacteria, protozoa, and fungi) in rumen fluids to the overall process of plant cell wall digestion in the rumen, representatives of these groups were selected by physical and chemical treatments of whole rumen fluid and used to construct an artificial rumen ecosystem. Physical treatments involved homogenization, centrifugation, filtration, and heat sterilization. Chemical treatments involved the addition of antibiotics and various chemicals to rumen fluid. To evaluate the potential activity and relative contribution to degradation of cell walls by specific microbial groups, the following fractions were prepared: a positive system (whole ruminal fluid), a bacterial (B) system, a protozoal (P) system, a fungal (F) system, and a negative system (cell-free rumen fluid). To assess the interactions between specific microbial fractions, mixed cultures (B+P, B+F, and P+F systems) were also assigned. Patterns of degradation due to the various treatments resulted in three distinct groups of data based on the degradation rate of cell wall material and on cell wall-degrading enzyme activities. The order of degradation was as follows: positive and F systems > B system > negative and P systems. Therefore, fungal activity was responsible for most of the cell wall degradation. Cell wall degradation by the anaerobic bacterial fraction was significantly less than by the fungal fraction, and the protozoal fraction failed to grow under the conditions used. In general, in the mixed culture systems the coculture systems demonstrated a decrease in cellulolysis compared with that of the monoculture systems. When one microbial fraction was associated with another microbial fraction, two types of results were obtained. The protozoal fraction inhibited cellulolysis of cell wall material by both the bacterial and the fungal fractions, while in the coculture between the bacterial fraction and the fungal fraction a synergistic interaction was detected.

Стилі APA, Harvard, Vancouver, ISO та ін.

17

Wilson, David B. "Three Microbial Strategies for Plant Cell Wall Degradation." Annals of the New York Academy of Sciences 1125, no. 1 (March 26, 2008): 289–97. http://dx.doi.org/10.1196/annals.1419.026.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

18

Stehle, T., and S. Zoll. "Bacterial cell wall degradation by a staphylococcal autolysin." Acta Crystallographica Section A Foundations of Crystallography 67, a1 (August 22, 2011): C90. http://dx.doi.org/10.1107/s0108767311097819.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

19

Marin-Rodriguez, M. C. "Pectate lyases, cell wall degradation and fruit softening." Journal of Experimental Botany 53, no. 377 (October 1, 2002): 2115–19. http://dx.doi.org/10.1093/jxb/erf089.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

20

Friedman, William E., and Martha E. Cook. "The origin and early evolution of tracheids in vascular plants: integration of palaeobotanical and neobotanical data." Philosophical Transactions of the Royal Society of London. Series B: Biological Sciences 355, no. 1398 (June 29, 2000): 857–68. http://dx.doi.org/10.1098/rstb.2000.0620.

Повний текст джерела

Анотація:

Although there is clear evidence for the establishment of terrestrial plant life by the end of the Ordovician, the fossil record indicates that land plants remained extremely small and structurally simple until the Late Silurian. Among the events associated with this first major radiation of land plants is the evolution of tracheids, complex water–conducting cells defined by the presence of lignified secondary cell wall thickenings. Recent palaeobotanical analyses indicate that Early Devonian tracheids appear to possess secondary cell wall thickenings composed of two distinct layers: a degradation–prone layer adjacent to the primary cell wall and a degradation–resistant (possibly lignified) layer next to the cell lumen. In order to understand better the early evolution of tracheids, developmental and comparative studies of key basal (and potentially plesiomorphic) extant vascular plants have been initiated. Ultra–structural analysis and enzyme degradation studies of wall structure (to approximate diagenetic alterations of fossil tracheid structure) have been conducted on basal members of each of the two major clades of extant vascular plants: Huperzia (Lycophytina) and Equisetum (Euphyllophytina). This research demonstrates that secondary cell walls of extant basal vascular plants include a degradation–prone layer (‘template layer’) and a degradation–resistant layer (‘resistant layer’). This pattern of secondary cell wall formation in the water–conducting cells of extant vascular plants matches the pattern of wall thickenings in the tracheids of early fossil vascular plants and provides a key evolutionary link between tracheids of living vascular plants and those of their earliest fossil ancestors. Further studies of tracheid development and structure among basal extant vascular plants will lead to a more precise reconstruction of the early evolution of water–conducting tissues in land plants, and will add to the current limited knowledge of spatial, temporal and cytochemical aspects of cell wall formation in tracheary elements of vascular plants.

Стилі APA, Harvard, Vancouver, ISO та ін.

21

Roy, S., W. S. Conway, A. E. Watada, G. Gillen, and W. P. Wergin. "ROLE OF CALCIUM IN REDUCING POSTHARVEST CELL WALL DEGRADATION IN `GOLDEN DELICIOUS' APPLE FRUIT." HortScience 30, no. 2 (April 1995): 191a—191. http://dx.doi.org/10.21273/hortsci.30.2.191a.

Повний текст джерела

Анотація:

Calcium is an important constituent of the cell wall and plays roles in maintaining firmness of fruit and reducing postharvest decay. The modification of the cell wall is believed to be influenced by calcium that interacts with acidic pectic polymers to form cross-bridges. Infiltrating apples with CaCl2 has been suggested as an effective postharvest treatment for increasing the calcium content. Three different methodologies were used to analyze the effects of calcium on the cell walls: 1) nickel staining of polygalacturonate on free-hand sections, 2) cationic gold labeling of anionic binding sites in the cell walls, and 3) analytical detection of calcium ions (40Ca, 44Ca) using a secondary ion mass spectrometry. The combination of these methods allowed us to directly visualize the cellular features associated with the infiltration of calcium. Treatment resulted in significant enrichment in the cell wall of the pericarp, transformed the acidic pectins in calcium pectates, and resulted in new calcium cross-bridges. Evidence now suggests that exogenously applied calcium affects the cell wall by enhancing its strength and reinforcing adhesion between neighbor cells; therefore, calcium infiltration delays fruit degradation.

Стилі APA, Harvard, Vancouver, ISO та ін.

22

Nicole, M., H. Chamberland, D. Rioux, X. Xixuan, G. B. Ouellette, R. A. Blanchette, and J. P. Geiger. "Wood degradation by Phellinus noxius: ultrastructure and cytochemistry." Canadian Journal of Microbiology 41, no. 3 (March 1, 1995): 253–65. http://dx.doi.org/10.1139/m95-035.

Повний текст джерела

Анотація:

An ultrastructural and cytochemical investigation of the development of Phellinus noxius, a white-rot fungus, in wood chips of Betula papyrifera was done to gain insight into the cellular mechanisms of wood cell wall degradation. Extracellular sheaths and microhyphae were seen to be involved in wood colonization. Close association was observed between these fungal structures and wood cell walls at both early and advanced stages of wood alteration. Fungal sheaths were often seen deep inside host cell walls, sometimes enclosing residual wood fragments. Investigations using gold probes indicated the occurrence of β-1,3-glucans within the fungal sheaths, while β-1,4-glucans were detected only within the fungal septa. The positive reaction with the PATAg test revealed that polysaccharides such as β-1,6-glucans were important components of the sheath. Chitin, pectin, β-glucosides, galactosamine, mannose, sialic acid, fucose, and fimbrial proteins were not found to be present in the sheath. Our data suggest that extracellular sheaths and microphyphae produced by P. noxius during wood cell wall colonization play an important role in wood degradation.Key words: cellulose, Phellinus, sheath, wood degradation.

Стилі APA, Harvard, Vancouver, ISO та ін.

23

Kim, Jong Sik, Jie Gao, Nasko Terziev, Ottaviano Allegretti, and Geoffrey Daniel. "Chemical and ultrastructural changes of ash wood thermally modified (TMW) using the thermo-vacuum process: II. Immunocytochemical study of the distribution of noncellulosic polysaccharides." Holzforschung 69, no. 5 (July 1, 2015): 615–25. http://dx.doi.org/10.1515/hf-2014-0149.

Повний текст джерела

Анотація:

AbstractFollowing structural and cytochemical studies (Part I) on thermally modified ash wood (TMW) by the thermo-vacuum (Termovuoto) process, changes in the distribution of noncellulosic polysaccharides have been investigated in TMW treated for 3 h at 220°C (TMW3 h, 220°C) by means of immunogold localization methods. Pectins (homogalacturonan, rhamnogalacturonan-I) and xyloglucan were significantly degraded in compound middle lamella (CML), including the middle lamella cell corner regions (CMLcc), of all xylem cells after thermal modification. Xylan and mannan degradation were also visible in fiber cell walls. In particular, degradation of mannan was very significant and showed variation between cell wall regions even within the same cell wall. The degradation of pectins was more significant than that of hemicelluloses. In summary, results suggest that each noncellulosic polysaccharide may have a different degradation process in ash TMWs.

Стилі APA, Harvard, Vancouver, ISO та ін.

24

Tsuneda, A., M. N. Thormann, and R. S. Currah. "Modes of cell-wall degradation of Sphagnum fuscum by Acremonium cf. curvulum and Oidiodendron maius." Canadian Journal of Botany 79, no. 1 (January 1, 2001): 93–100. http://dx.doi.org/10.1139/b00-149.

Повний текст джерела

Анотація:

Electron microscopy of cryo-fractured hyaline leaf cells of Sphagnum fuscum Klinggr. revealed that their cell walls consist of three layers: a thick central layer flanked on either side by a thinner, amorphous layer. Acremonium cf. curvulum W. Gams and Oidiodendron maius Barron, both isolated from partly decomposed S. fuscum plants, were capable of degrading leaf cell walls of Sphagnum. Where hyphae of A. curvulum accumulated, the amorphous, outer wall layer of S. fuscum was first fragmented and then removed. The exposed central wall layer consisted of bundles of microfibrils embedded in an amorphous matrix material. After the matrix material and the inner surface wall layer were mostly removed, degradation of microfibrils occurred and localized voids were produced. Unlike A. cf. curvulum, O. maius degraded all wall components more or less simultaneously. In both fungi, active and autolysing hyphae frequently occurred in proximity on the Sphagnum leaves.Key words: hyphomycetes, peat, phenolics, cellulose, SEM.

Стилі APA, Harvard, Vancouver, ISO та ін.

25

HUBER, DONALD J., YASAR KARAKURT, and JIWON JEONG. "Pectin degradation in ripening and wounded fruits." Revista Brasileira de Fisiologia Vegetal 13, no. 2 (2001): 224–41. http://dx.doi.org/10.1590/s0103-31312001000200009.

Повний текст джерела

Анотація:

Pectin depolymerization during fruit ripening has been shown to be largely due to pectinolytic enzymes, including polygalacturonases (E.C. 3.2.1.15) and pectinmethylesterases (E.C. 3.2.1.11). Studies have shown that these enzymes are not the primary determinants of softening, although participation in texture changes during the late stages of ripening seems evident. Pectin depolymerization differs significantly between various fruit types, notably avocado and tomato, even though levels of extractable PG activity in these fruits are similar. Collective evidence indicates that the activities of some cell wall enzymes are restricted in vivo, with maximum hydrolytic potential expressed only in response to tissue disruption or wounding. In contrast, other enzymes reported to participate in pectin degradation, notably beta-galactosidases/exo-galactanases, exhibit in vitro activity far below that anticipated to be required for the loss of cell wall galactosyl residues during ripening. Factors controlling in vivo hydrolysis have not been fully explored but might include apoplastic pH, cell wall inorganic ion levels, non-enzymic proteins including the noncatalytic beta-subunit and expansins, wall porosity, and steric hindrances. Recent studies of cell wall metabolism during ripening have demonstrated an orderly process involving, in the early stages, cell wall relaxation and hemicellulose degradation followed, in the later stages, by pectin depolymerization. A limited number of studies have indicated that radical oxygen species generated either enzymically or non-enzymically might participate in scission of pectins and other polysaccharides during ripening and other developmental processes. Similar mechanisms might also occur in response to wounding, an event typically followed by an oxidative burst. Cell wall degradation as influenced by physical wounding could be of particular relevance to the deterioration of lightly processed fruits.

Стилі APA, Harvard, Vancouver, ISO та ін.

26

Blanchette, Robert A. "Degradation of the lignocellulose complex in wood." Canadian Journal of Botany 73, S1 (December 31, 1995): 999–1010. http://dx.doi.org/10.1139/b95-350.

Повний текст джерела

Анотація:

Degradation of the lignocellulose complex in wood varies depending on the microorganism causing decay. The degradative processes of white-, brown-, and soft-rot fungi as well as different forms of bacterial degradation are presented. Ultrastructural methods were used to elucidate cell-wall alterations that occurred during the various stages of decay. In wood inoculated with the white-rot fungus Ceriporiopsis subvermispora, changes in the cell wall, such as electron-dense zones after staining with uranyl acetate, were evident during incipient stages of decay. The ratio of syringyl:guaiacyl lignin of different woods, different cell types, and even the different layers within a cell wall influenced the type and extent of decay by white-rot fungi. Soft rots caused unique changes in the lignocellulose matrix. The type of wood substrate governed the form (type I or type II) of soft rot that occurred. Brown-rot fungi depolymerized cellulose early in the decay process and degraded cellulose without prior removal of lignin. Bacterial degradation was common in waterlogged woods and three forms, tunneling, erosion and cavitation, are discussed. In addition to an improved understanding of decay processes in living trees and forest products, knowledge of decomposition mechanisms is important to utilize effectively these microorganisms for new industrial bioprocessing technologies. Key words: biodegradation, white rot, brown rot, soft rot, bacterial degradation.

Стилі APA, Harvard, Vancouver, ISO та ін.

27

Laaksamo, Elisa, Riikka Tulamo, Arto Liiman, Marc Baumann, Robert M. Friedlander, Juha Hernesniemi, Marko Kangasniemi, Mika Niemelä, Aki Laakso, and Juhana Frösen. "Oxidative Stress Is Associated With Cell Death, Wall Degradation, and Increased Risk of Rupture of the Intracranial Aneurysm Wall." Neurosurgery 72, no. 1 (October 23, 2012): 109–17. http://dx.doi.org/10.1227/neu.0b013e3182770e8c.

Повний текст джерела

Анотація:

Abstract BACKGROUND: The cause of rupture of intracranial aneurysms (IA) is not well understood. We previously demonstrated that loss of cells from the IA wall is associated with wall degeneration and rupture. OBJECTIVE: To investigate the mechanisms mediating cell death in the IA wall. METHODS: Snap-frozen tissue samples from aneurysm fundi were studied with terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL) staining and immunostaining (14 unruptured and 20 ruptured), as well as with Western blot (12 unruptured and 12 ruptured). RESULTS: Ruptured IA walls had more TUNEL-positive cells than unruptured walls (P < .001). Few cells positive for cleaved caspase-3 were detected. Cleaved caspase-9 (intrinsic activation of apoptosis) was significantly increased in ruptured IA walls, whereas cleaved caspase-8 (extrinsic activation of apoptosis) was not detected. Increased expression of hemeoxygenase-1, a marker for oxidative stress, was associated with IA wall degeneration and rupture. CONCLUSION: Our results show that programmed cell death is activated in the IA wall via the intrinsic pathway. High oxidative stress in the IA wall is probably a significant cause of the intrinsic activation of cell death.

Стилі APA, Harvard, Vancouver, ISO та ін.

28

Li, X. "Plant cell wall chemistry: implications for ruminant utilisation." Journal of Applied Animal Nutrition 9, no. 1 (May 21, 2021): 31–56. http://dx.doi.org/10.3920/jaan2020.0017.

Повний текст джерела

Анотація:

Ruminants have adapted to cope with bulky, fibrous forage diets by accommodating a large, diverse microbial population in the reticulo-rumen. Ruminants are dependent on forages as their main sources of energy and other nutrients. Forages are comprised of a complex matrix of cellulose, hemicellulose, protein, minerals and phenolic compounds (including lignin and tannins) with various linkages; many of which are poorly defined. The composition and characteristics of polysaccharides vary greatly among forages and plant cell walls. Plant cell walls are linked and packed together in tight configurations to resist degradation, and hence their nutritional value to animals varies considerably, depending on composition, structure and degradability. An understanding of the inter-relationship between the chemical composition and the degradation of plant cell walls by rumen microorganisms is of major economic importance to ruminant production. Increasing the efficiency of fibre degradation in the rumen has been the subject of extensive research for many decades. This review summarises current knowledge of forage chemistry in order to develop strategies to increase efficiency of forage utilisation by ruminants.

Стилі APA, Harvard, Vancouver, ISO та ін.

29

Brummell, David A. "Cell wall disassembly in ripening fruit." Functional Plant Biology 33, no. 2 (2006): 103. http://dx.doi.org/10.1071/fp05234.

Повний текст джерела

Анотація:

Fruit softening during ripening involves a coordinated series of modifications to the polysaccharide components of the primary cell wall and middle lamella, resulting in a weakening of the structure. Degradation of polysaccharides and alterations in the bonding between polymers cause an increase in cell separation and a softening and swelling of the wall, which, combined with alterations in turgor, bring about fruit softening and textural changes. A wide range in the extent of cell wall pectic modifications has been observed between species, whereas the depolymerisation of xyloglucan is relatively limited and more consistent. The earliest events to be initiated are usually a loss of pectic galactan side chains and the depolymerisation of matrix glycans, which may begin before ripening, followed by a loss of pectic arabinan side chains and pectin solubilisation. The depolymerisation of pectins may begin during early to mid-ripening, but is usually most pronounced late in ripening. However, some of these events may be absent or occur at very low levels in some species. Cell wall swelling may be related to a loosening of the xyloglucan–cellulose network and to pectin solubilisation, and these processes combined with the loss of pectic side chains increase wall porosity. An increase in wall porosity later in ripening may allow increased access of degradative enzymes to their substrates.

Стилі APA, Harvard, Vancouver, ISO та ін.

30

Ward, Owen P., M. Moo-young, and K. Venkat. "Enzymatic Degradation of Cell Wall and Related Plant Polysaccharides." Critical Reviews in Biotechnology 8, no. 4 (January 1989): 237–74. http://dx.doi.org/10.3109/07388558909148194.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

31

Vallarino, José G., and Sonia Osorio. "Signaling role of oligogalacturonides derived during cell wall degradation." Plant Signaling & Behavior 7, no. 11 (November 2012): 1447–49. http://dx.doi.org/10.4161/psb.21779.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

32

Travis, AJ, MJ Metcalf, and A. Chesson. "Computer simulation of cell wall degradation using cellular automata." Reproduction Nutrition Development 37, Suppl. 1 (1997): 60–61. http://dx.doi.org/10.1051/rnd:19970741.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

33

Minic, Z., and L. Jouanin. "Plant glycoside hydrolases involved in cell wall polysaccharide degradation." Plant Physiology and Biochemistry 44, no. 7-9 (July 2006): 435–49. http://dx.doi.org/10.1016/j.plaphy.2006.08.001.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

34

Huisman, M. M. H., H. A. Schols, and A. G. J. Voragen. "Enzymatic degradation of cell wall polysaccharides from soybean meal." Carbohydrate Polymers 38, no. 4 (April 1999): 299–307. http://dx.doi.org/10.1016/s0144-8617(98)00127-1.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

35

Nilsson, T., and G. Daniel. "Microscopic evidence for wood cell wall degradation by actinomycetes." Holz als Roh- und Werkstoff 48, no. 9 (September 1990): 360. http://dx.doi.org/10.1007/bf02639901.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

36

Akin, Danny E. "Plant cell wall aromatics: influence on degradation of biomass." Biofuels, Bioproducts and Biorefining 2, no. 4 (July 2008): 288–303. http://dx.doi.org/10.1002/bbb.76.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

37

Selvig, A., H. Aarnes, and S. Lie. "CELL WALL DEGRADATION IN ENDOSPERM OF BARLEY DURING GERMINATION." Journal of the Institute of Brewing 92, no. 2 (March 4, 1986): 185–87. http://dx.doi.org/10.1002/j.2050-0416.1986.tb04396.x.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

38

Wilson, J. R., and R. D. Hatfield. "Structural and chemical changes of cell wall types during stem development: consequences for fibre degradation by rumen microflora." Australian Journal of Agricultural Research 48, no. 2 (1997): 165. http://dx.doi.org/10.1071/a96051.

Повний текст джерела

Анотація:

Legume and grass stems decrease substantially in digestibility as they mature. This review evaluates how anatomical and chemical factors restrict digestion of cell walls in legume and grass stems. Cells that make up legume stems fall into 2 groups: cells with high (≅ 100%) digestibility (e.g. cortex and pith) and cells that appear indigestible (e.g. xylem). The digestibility of xylem cells is restricted by the highly lignified secondary walls (SW). Although cortex and pith cells may develop SW or thickened primary walls, digestibility is high because these cell types do not undergo lignification. In contrast, as grass stems mature, SW thickening and lignification occur in all main cell types. However, lignified SW in grass is readily digested when accessible to rumen microorganisms. Analysis of tissue and cell architecture in grasses strongly supports the hypothesis that observed poor digestion of lignified SW in vivo is due to limits imposed by anatomical structure. Compositional limitation to wall digestion lies in the lignified, indigestible middle lamella–primary wall. This structure confines SW digestion to inner (lumen) surfaces of cells with an open end. Low sclerenchyma SW degradation in vivo can be explained by limited movement of bacteria into sclerenchyma cells and low surface area on interior walls. For example, the ratio of surface area to total cell wall volume for sclerenchyma cells is 100-fold lower than for mesophyll cells. Apparent relationships of some wall constituents–chemical structures to wall digestibility may be the result of the increasing SW and, therefore, may simply reflect limitations imposed by anatomical structure.

Стилі APA, Harvard, Vancouver, ISO та ін.

39

Ylimartimo, A., G. Laflamme, M. Simard, and D. Rioux. "Ultrastructure and cytochemistry of early stages of colonization by Gremmeniella abietina in Pinus resinosa seedlings." Canadian Journal of Botany 75, no. 7 (July 1, 1997): 1119–32. http://dx.doi.org/10.1139/b97-123.

Повний текст джерела

Анотація:

This paper provides details on the infection processes at the ultrastructural level in Pinus resinosa Ait. seedlings during early stages of colonization by Gremmeniella abietina (Lagerb.) Morelot. Different gold-conjugated enzymes and antibodies were used to cytochemically localize cellulose, pectin, fungal laccase, and the pathogen cells in host tissues. Gremmeniella abietina penetrated into the host through stomata of the short shoot bracts and sparsely colonized both intercellular and intracellular areas of the bract tissues. The colonizing hyphae usually had a thick wall surrounded by an extracellular sheath composed of fibrillar material. Microhyphaelike cells were observed as having penetrated host cell walls. The fungal cells (except the extracellular sheath), even when embedded in cellulosic or pectic material of host tissues, did not appear to contain cellulose or pectin. We suggest that G. abietina is able to degrade cellulose and pectin and that phenoloxidases secreted by the pathogen could be involved in host cell wall degradation. The results indicate that the extracellular sheath of G. abietina is implicated in host–pathogen interactions such as attachment of hyphae to the host surface and cell wall degradation during colonization of host tissues. Key words: Gremmeniella, Pinus, infection processes, cell wall degradation, extracellular fungal sheath, gold labelling.

Стилі APA, Harvard, Vancouver, ISO та ін.

40

Xu, Haixin, and Kurt Mendgen. "Targeted Cell Wall Degradation at the Penetration Site of Cowpea Rust Basidiosporelings." Molecular Plant-Microbe Interactions® 10, no. 1 (January 1997): 87–94. http://dx.doi.org/10.1094/mpmi.1997.10.1.87.

Повний текст джерела

Анотація:

Basidiospore germlings of the cowpea rust fungus (Uromyces vignae) penetrate the epidermal cell wall of the nonhost plant Vicia faba. In order to characterize the wall structure of the penetration site, leaves were high pressure frozen, freeze substituted, and embedded in appropriate resins. With antibodies against epitopes present in pectin, polygalacturonic acid, xyloglucan, and callose, we studied the modification of these wall components during infection. The density of epitopes was determined at the penetration site and compared with noninfected areas of the epidermal wall. Along the fungal penetration hypha, a zone of the plant wall, 0.2 μm wide, exhibited a reduced density of pectin and xyloglucan epitopes. A similar reduction of epitope density was also found for xyloglucan after treatment of sections from noninoculated plants with cellulase and xylanase and for pectin after treatment with pectinase. The density of polygalacturonic acid epitopes remained unchanged in the outer layer of the epidermal wall, but increased over the inner layer. A high density of polygalacturonic acid epitopes was found over a collarlike wall apposition produced by the plant cell along the penetration hypha. These results indicate that the fungus degrades the plant cell wall at the penetration site and that the plant cell secretes new wall material into this area to form the wall apposition.

Стилі APA, Harvard, Vancouver, ISO та ін.

41

de Vries, Ronald P., and Jaap Visser. "Aspergillus Enzymes Involved in Degradation of Plant Cell Wall Polysaccharides." Microbiology and Molecular Biology Reviews 65, no. 4 (December 1, 2001): 497–522. http://dx.doi.org/10.1128/mmbr.65.4.497-522.2001.

Повний текст джерела

Анотація:

SUMMARY Degradation of plant cell wall polysaccharides is of major importance in the food and feed, beverage, textile, and paper and pulp industries, as well as in several other industrial production processes. Enzymatic degradation of these polymers has received attention for many years and is becoming a more and more attractive alternative to chemical and mechanical processes. Over the past 15 years, much progress has been made in elucidating the structural characteristics of these polysaccharides and in characterizing the enzymes involved in their degradation and the genes of biotechnologically relevant microorganisms encoding these enzymes. The members of the fungal genus Aspergillus are commonly used for the production of polysaccharide-degrading enzymes. This genus produces a wide spectrum of cell wall-degrading enzymes, allowing not only complete degradation of the polysaccharides but also tailored modifications by using specific enzymes purified from these fungi. This review summarizes our current knowledge of the cell wall polysaccharide-degrading enzymes from aspergilli and the genes by which they are encoded.

Стилі APA, Harvard, Vancouver, ISO та ін.

42

Mamoňová, Miroslava, and Ladislav Reinprecht. "The impact of natural and artificial weathering on the anatomy of selected tropical hardwoods." IAWA Journal 41, no. 3 (July 28, 2020): 333–55. http://dx.doi.org/10.1163/22941932-bja10028.

Повний текст джерела

Анотація:

Abstract The effect of natural and artificial weathering on the anatomy of seven tropical hardwoods: Bangkirai (Shorea obtusa Wall.), Cumaru (Dipteryx odorata (Aubl.) Wild.), Cumaru Rosa (Dipteryx magnifica (Ducke) Ducke), Ipé (Tabebuia serratifolia Nichols.), Jatobá (Hymenaea courbaril L.), Kusia (Nauclea diderrichii Merill) and Massaranduba (Manilkara bidentata A. Chev.), was studied. As a result of weathering some characteristic anatomical changes occurred: the weakening of connections between cell elements related to the degradation of the middle lamella; micro-cracks in cell walls; total degradation of parenchyma cells in xylem rays, or significant thinning of parenchyma cell walls and their extreme shrinkage; micro-cracks in the vicinity of xylem rays; significant transversal disruptions in libriform fibres; ablation of pit membranes in vessels and parenchyma cells; changes in the secondary wall of libriform fibres, for example, their defibrillation and weathering-degradation of the S1 layer; and spherical formations on the S3 layer of cell walls produced from condensing compounds of degraded lignin and hemicelluloses as well as thermo-mechanical wrinkling. The highest incidence of micro-cracks after both modes of weathering was found in the densest species; Cumaru, Ipé, and Massaranduba.

Стилі APA, Harvard, Vancouver, ISO та ін.

43

VARDAR, Filiz, and Meral ÜNAL. "Immunolocalization of Lipoxygenase in the Anther Wall Cells of Lathyrus undulatus Boiss. during Programmed Cell Death." Notulae Botanicae Horti Agrobotanici Cluj-Napoca 39, no. 1 (May 30, 2011): 71. http://dx.doi.org/10.15835/nbha3915865.

Повний текст джерела

Анотація:

Lipoxygenase catalyzes oxygenation of long chain fatty acids to hydroperoxides and is involved in the degradation of membranes occuring in some types of programmed cell death (PCD). The localization of lipoxygenase in the anther wall layers of L. undulatus during cellular degradation was analyzed by immunogold labeling technique at young and vacuolated pollen stage, due to the close relation between lipoxygenase activity and membrane degradation in programmed cell death. Immunoreaction to lipoxygenase was monitored slightly at young pollen stage in the anther wall cells. As programmed cell death signals progress, lipoxygenase revealed in anther wall cells intensely. At vacuolated pollen stage tapetal cells came forward with ultrastructural changes such as cell, organelle and membrane disintegration. At the indicated stage immunogold particles indicating sites of LOX PAb-binding epitopes were located in the nucleus (chromatin was condensed and lined at the periphery), cytoplasm and close to long dilated rough endoplasmic reticulum (RER) cisterna. In conclusion lipoxygenase increase which has a role in the membrane degeneration, possibly induced the collapse of tonoplast, nuclear and plasma membrane and triggered programmed cell death in the tapetal cells of L. undulatus as well as the other wall cells.

Стилі APA, Harvard, Vancouver, ISO та ін.

44

Murashima, Koichiro, Akihiko Kosugi, and Roy H. Doi. "Determination of Subunit Composition of Clostridium cellulovorans Cellulosomes That Degrade Plant Cell Walls." Applied and Environmental Microbiology 68, no. 4 (April 2002): 1610–15. http://dx.doi.org/10.1128/aem.68.4.1610-1615.2002.

Повний текст джерела

Анотація:

ABSTRACT Clostridium cellulovorans produces a cellulase enzyme complex (cellulosome). In this study, we isolated two plant cell wall-degrading cellulosomal fractions from culture supernatant of C. cellulovorans and determined their subunit compositions and enzymatic activities. One of the cellulosomal fractions showed fourfold-higher plant cell wall-degrading activity than the other. Both cellulosomal fractions contained the same nine subunits (the scaffolding protein CbpA, endoglucanases EngE and EngK, cellobiohydrolase ExgS, xylanase XynA, mannanase ManA, and three unknown proteins), although the relative amounts of the subunits differed. Since only cellobiose was released from plant cell walls by the cellulosomal fractions, cellobiohydrolases were considered to be key enzymes for plant cell wall degradation.

Стилі APA, Harvard, Vancouver, ISO та ін.

45

Ismail, I. M. K., Tahany M. A. Abdel Rahman, Esmat E. A. Elwy, and M. E. Osman. "Effect of the triazine herbicides Goltix and Igran on cell wall degradation by some fungi." Canadian Journal of Botany 67, no. 3 (March 1, 1989): 834–38. http://dx.doi.org/10.1139/b89-112.

Повний текст джерела

Анотація:

Fifteen-day-old tomato and cotton hypocotyls were susceptible to degradation by the three fungi Aspergillus fumigatus, Fusarium oxysporum f.sp. lycopersici, and Fusarium oxysporum f.sp. vasinfectum. The last two fungi cause tomato and cotton wilts in Egypt. Addition of various concentrations (50–1200 ppm) of Goltix (4-amino-3-methyl-6-phenyl-1,2,4-triazine-5 (4H)-one(IUPAC)) inhibited the tomato cell wall degradation by the tested fungi except its pathogen, while the doses (50–1200 ppm) of Igran (4-ethylamino-2-tert-butylamino-6-methylthio-5-triazine) inhibited tomato cell wall degradation by the three fungi. On the other hand, the addition of various concentrations of Goltix to cotton cell wall culture increased the susceptibility of the cell wall to the degrading enzymes of the three fungi, while Igran inhibited the degradation by the two Fusarium species. The data also emphasized the presence of xylanase, arabanase, mannanase, galactanase, and cellulase enzymes in both tomato and cotton cell wall cultures of the tested fungi. Higher doses of either Goltix or Igran (800 and 1200 ppm) completely inhibited the activation of arabanase, xylanase, and mannanase, while cellulase and galactanase were less sensitive to the applied herbicide doses.

Стилі APA, Harvard, Vancouver, ISO та ін.

46

Hasper, Alinda A., Ester Dekkers, Marc van Mil, Peter J. I. van de Vondervoort, and Leo H. de Graaff. "EglC, a New Endoglucanase from Aspergillus niger with Major Activity towards Xyloglucan." Applied and Environmental Microbiology 68, no. 4 (April 2002): 1556–60. http://dx.doi.org/10.1128/aem.68.4.1556-1560.2002.

Повний текст джерела

Анотація:

ABSTRACT A novel gene, eglC, encoding an endoglucanase, was cloned from Aspergillus niger. Transcription of eglC is regulated by XlnR, a transcriptional activator that controls the degradation of polysaccharides in plant cell walls. EglC is an 858-amino-acid protein and contains a conserved C-terminal cellulose-binding domain. EglC can be classified in glycoside hydrolase family 74. No homology to any of the endoglucanases from Trichoderma reesei was found. In the plant cell wall xyloglucan is closely linked to cellulose fibrils. We hypothesize that the EglC cellulose-binding domain anchors the enzyme to the cellulose chains while it is cleaving the xyloglucan backbone. By this action it may contribute to the degradation of the plant cell wall structure together with other enzymes, including hemicellulases and cellulases. EglC is most active towards xyloglucan and therefore is functionally different from the other two endoglucanases from A. niger, EglA and EglB, which exhibit the greatest activity towards β-glucan. Although the mode of action of EglC is not known, this enzyme represents a new enzyme function involved in plant cell wall polysaccharide degradation by A. niger.

Стилі APA, Harvard, Vancouver, ISO та ін.

47

Massicotte, H. B., C. A. Ackerley, and R. L. Peterson. "Localization of three sugar residues in the interface of ectomycorrhizae synthesized between Alnus crispa and Alpova diplophloeus as demonstrated by lectin binding." Canadian Journal of Botany 65, no. 6 (June 1, 1987): 1127–32. http://dx.doi.org/10.1139/b87-157.

Повний текст джерела

Анотація:

The interface established between Alnus crispa and the basidiomycete Alpova diplophloeus involves structural modifications of host cell walls and hyphal walls in the Hartig net region of the ectomycorrhizae synthesized in pouches. Indirect labelling of cell wall carbohydrates by using colloidal gold conjugated with the lectins Ulex europaeus agglutinin, wheat-germ agglutinin, and concanavalin A was applied to these mycorrhizae and to nonmycorrhizal roots. Significantly more binding of the lectins was observed in the mycorrhizal roots than in control roots. In the Hartig net region of mycorrhizal roots, the lectins bound intensely to the host cell wall, particularly the wall ingrowths, and to adjacent fungal walls, whereas in nonmycorrhizal roots, a sparse labelling was recorded in the cell wall. Possible explanations for this pattern of lectin binding include the following: the sugar residues L-fucose, mannose, and N-acetylglucosamine may be utilized in the synthesis of the elaborate epidermal wall ingrowths and N-acetylglucosamine may be utilized in the synthesis of the labyrinthine wall branchings of the fungus; the sugar residues are bound to a proteinaceous fraction in the host and hyphal walls; the sugar residues bound by the lectins may be components of defense reaction elicitors released from the host wall and hyphal wall by wall-degrading enzymes; the sugar residues may simply be the result of enzymatic degradation of walls but not involving elicitors of defense reactions.

Стилі APA, Harvard, Vancouver, ISO та ін.

48

Wagner, Leopold, Thomas K. Bader, Thomas Ters, Karin Fackler, and Karin de Borst. "A combined view on composition, molecular structure, and micromechanics of fungal degraded softwood." Holzforschung 69, no. 4 (May 1, 2015): 471–82. http://dx.doi.org/10.1515/hf-2014-0023.

Повний текст джерела

Анотація:

Abstract Fungal decay alters the composition, microstructure, and mechanical properties of wood cell walls. To understand better the structure-function relationships during fungal decay, selected annual rings of fungal deteriorated Scots pine sapwood were analyzed in terms of their composition, microstructure, and micromechanical properties. The datasets were acquired separately for earlywood and latewood concerning the S2 cell wall layer and the cell corner middle lamella (CCML) and analyzed by means of principal component analysis and partial least squares regression analysis. Links between cell wall stiffness and hardness and the composition and microstructure could be established. Increased mechanical properties in the CCML, as obtained by nanoindentation, were correlated to the degradation of pectins. In the S2 layer, the altered data were related to the degradation of hemicelluloses and lignin modification during fungal decay.

Стилі APA, Harvard, Vancouver, ISO та ін.

49

Weber, Sophie, Philipp M. Grande, Lars M. Blank, and Holger Klose. "Insights into cell wall disintegration of Chlorella vulgaris." PLOS ONE 17, no. 1 (January 14, 2022): e0262500. http://dx.doi.org/10.1371/journal.pone.0262500.

Повний текст джерела

Анотація:

With their ability of CO2 fixation using sunlight as an energy source, algae and especially microalgae are moving into the focus for the production of proteins and other valuable compounds. However, the valorization of algal biomass depends on the effective disruption of the recalcitrant microalgal cell wall. Especially cell walls of Chlorella species proved to be very robust. The wall structures that are responsible for this robustness have been studied less so far. Here, we evaluate different common methods to break up the algal cell wall effectively and measure the success by protein and carbohydrate release. Subsequently, we investigate algal cell wall features playing a role in the wall’s recalcitrance towards disruption. Using different mechanical and chemical technologies, alkali catalyzed hydrolysis of the Chlorella vulgaris cells proved to be especially effective in solubilizing up to 56 wt% protein and 14 wt% carbohydrates of the total biomass. The stepwise degradation of C. vulgaris cell walls using a series of chemicals with increasingly strong conditions revealed that each fraction released different ratios of proteins and carbohydrates. A detailed analysis of the monosaccharide composition of the cell wall extracted in each step identified possible factors for the robustness of the cell wall. In particular, the presence of chitin or chitin-like polymers was indicated by glucosamine found in strong alkali extracts. The presence of highly ordered starch or cellulose was indicated by glucose detected in strong acidic extracts. Our results might help to tailor more specific efforts to disrupt Chlorella cell walls and help to valorize microalgae biomass.

Стилі APA, Harvard, Vancouver, ISO та ін.

50

Bosman, M. T. M. "Some Effects of Decay and Weathering on the Anatomical Structure of the Stem of Phragmites Australis Trin. Ex Steud." IAWA Journal 6, no. 2 (1985): 165–70. http://dx.doi.org/10.1163/22941932-90000929.

Повний текст джерела

Анотація:

Effects of decay and weathering on the stems of Phragmites australis Trin. ex Steud. were studied on material used for thatching. Decay appeared to be mainly a result of fungal attack and ultra-violet radiation. Biological degradation by soft-rot fungi causes a considerable loss of cell wall constituents towards the exposed basal part of the stems. In sclerenchyma and parenchyma (excl. the subepidermal tissues) this effect is visible as diamond-shaped cavities, spirally arranged in the central part of the secondary cell walls (following the microfibrillar arrangement). A second type of fungal attack is observed in stems obtained from a byre. Here the cell walls are thinned from the lumen side towards the external wall layers, showing in longitudinal section cells with locally enlarged lumina. At the exposed parts of the stem superficial weathering by ultra-violet radiation causes degradation of lignin. Thus the middle lamella region disintegrates and the outer cell layers peel off.

Стилі APA, Harvard, Vancouver, ISO та ін.

Статті в журналах з теми "Cell wall degradation"

Оформте джерело за APA, MLA, Chicago, Harvard та іншими стилями