Showing papers on "Chitin published in 2007"
TL;DR: CERK1 is a plasma membrane protein containing three LysM motifs in the extracellular domain and an intracellular Ser/Thr kinase domain with autophosphorylation/myelin basic protein kinase activity, suggesting that CERK 1 plays a critical role in fungal MAMP perception in plants.
Abstract: Chitin is a major component of fungal cell walls and serves as a microbe-associated molecular pattern (MAMP) for the detection of various potential pathogens in innate immune systems of both plants and animals. We recently showed that chitin elicitor-binding protein (CEBiP), plasma membrane glycoprotein with LysM motifs, functions as a cell surface receptor for chitin elicitor in rice. The predicted structure of CEBiP does not contain any intracellular domains, suggesting that an additional component(s) is required for signaling through the plasma membrane into the cytoplasm. Here, we identified a receptor-like kinase, designated CERK1, which is essential for chitin elicitor signaling in Arabidopsis. The KO mutants for CERK1 completely lost the ability to respond to the chitin elicitor, including MAPK activation, reactive oxygen species generation, and gene expression. Disease resistance of the KO mutant against an incompatible fungus, Alternaria brassicicola, was partly impaired. Complementation with the WT CERK1 gene showed cerk1 mutations were responsible for the mutant phenotypes. CERK1 is a plasma membrane protein containing three LysM motifs in the extracellular domain and an intracellular Ser/Thr kinase domain with autophosphorylation/myelin basic protein kinase activity, suggesting that CERK1 plays a critical role in fungal MAMP perception in plants.
1,222 citations
TL;DR: The net cationicity as well as the presence of multiple reactive functional groups in the molecule make chitosan a sought-after biomolecule and offers scope for manipulation for preparing a broad spectrum of derivatives for specific end use applications in diversified areas.
Abstract: Use of natural biopolymers for diversified applications in life sciences has several advantages, such as availability from replenishable agricultural or marine food resources, biocompatibility, biodegradability, therefore leading to ecological safety and the possibility of preparing a variety of chemically or enzymatically modified derivatives for specific end uses. Polysaccharides, as a class of natural macromolecules, have the tendency to be extremely bioactive, and are generally derived from agricultural feedstock or crustacean shell wastes. Cellulose, starch, pectin, etc. are the biopolymers derived from the former while chitin and chitosan are obtained from the latter. In terms of availability, chitin is next to cellulose, available to the extent of over 10 gigatons annually. The application potential of chitosan, a deacetylated derivative of chitin, is multidimensional, such as in food and nutrition, biotechnology, material science, drugs and pharmaceuticals, agriculture and environmental protection, and recently in gene therapy too. The net cationicity as well as the presence of multiple reactive functional groups in the molecule make chitosan a sought-after biomolecule. The latter offers scope for manipulation for preparing a broad spectrum of derivatives for specific end use applications in diversified areas. The biomedical and therapeutic significance of chitin/chitosan derivatives is a subject of significant concern to many all over the world. An attempt is made in this overview to consolidate some of the recent findings on the biorelated application potential of chitosan and its derivatives.
1,011 citations
TL;DR: It is shown that chitin induces the accumulation in tissue of IL-4-expressing innate immune cells, including eosinophils and basophils, when given to mice, and this process can be negatively regulated by a vertebrate chit inase.
Abstract: Allergic and parasitic worm immunity is characterized by infiltration of tissues with interleukin (IL)-4- and IL-13-expressing cells, including T-helper-2 cells, eosinophils and basophils. Tissue macrophages assume a distinct phenotype, designated alternatively activated macrophages. Relatively little is known about the factors that trigger these host responses. Chitin, a widespread environmental biopolymer of N-acetyl-beta-D-glucosamine, provides structural rigidity to fungi, crustaceans, helminths and insects. Here, we show that chitin induces the accumulation in tissue of IL-4-expressing innate immune cells, including eosinophils and basophils, when given to mice. Tissue infiltration was unaffected by the absence of Toll-like-receptor-mediated lipopolysaccharide recognition but did not occur if the injected chitin was pre-treated with the IL-4- and IL-13-inducible mammalian chitinase, AMCase, or if the chitin was injected into mice that overexpressed AMCase. Chitin mediated alternative macrophage activation in vivo and the production of leukotriene B(4), which was required for optimal immune cell recruitment. Chitin is a recognition element for tissue infiltration by innate cells implicated in allergic and helminth immunity and this process can be negatively regulated by a vertebrate chitinase.
738 citations
TL;DR: Chitin is the world's second most abundant naturally occurring polysaccharide, and due to its widespread abundance, its chemical and physical versatility, and the problems of its disposal as a waste material, a wide range of value-added applications of chitin and chitosan are being initiated, investigated, and developed.
Abstract: Chitin is the world's second most abundant naturally occurring polysaccharide. Much of this is disposed of as waste from seafood crustacean, mainly in shrimps, prawns, crabs, and lobsters, where it occurs as a significant component in the shells/exoskeletons of crustacea. Due to its widespread abundance, its chemical and physical versatility, and the problems of its disposal as a waste material, a wide range of value-added applications of chitin and chitosan is being initiated, investigated, and developed. The widely ranging value-added applications of chitin and chitosan are presented in this review. Chitin and its derivative, chitosan, both highly stable and difficult to degrade materials, can be obtained as 10–20% w/w from the waste seafood shells by suitable chemical processing. One of the significant developments in the new range of applications is the study of the ability of chitosan, as a potentially major environmental treatment material, to remove metal ions from wastewaters. Chitosan is the deac...
694 citations
TL;DR: Sulfated chitin and chitosan are promising materials for biomedical applications according to current research and existing products and some new and futuristic approaches in this context area are discussed in detail.
604 citations
TL;DR: Some of the chitinases produced by bacterial systems that have gained worldwide research interest for their diverse properties and potential industrial uses are reviewed.
Abstract: Chitin is among the most abundant biomass present on Earth. Chitinase plays an important role in the decomposition of chitin and potentially in the utilization of chitin as a renewable resource. During the previous decade, chitinases have received increased attention because of their wide range of applications. Chito-oligomers produced by enzymatic hydrolysis of chitin have been of interest in recent years due to their broad applications in medical, agricultural, and industrial applications, including antibacterial, antifungal, hypocholesterolemic, and antihypertensive activity, and as a food quality enhancer. Microorganisms, particularly bacteria, form one of the major sources of chitinase. In this article, we have reviewed some of the chitinases produced by bacterial systems that have gained worldwide research interest for their diverse properties and potential industrial uses.
385 citations
TL;DR: Data suggest that for the species measured here the amount of chitin nitrogen is quite small and that crude protein provides a reasonable estimate of the true protein for most species of insects.
Abstract: Insects contain significant amounts of fiber as measured by crude fiber, acid detergent fiber (ADF) or neutral detergent fiber (NDF). It has always been assumed that the fiber in insects represents chitin based on the structural similarity between cellulose and chitin and the fact that the ADF fraction from insects contains nitrogen. In this study, a number of insect species that are raised commercially as food for insectivores were analyzed for moisture, crude protein (nitrogen × 6.25), fat, ash, NDF, ADF, and amino acids. Additionally, the ADF fraction was analyzed for nitrogen and amino acids to determine if proteins might be present in the ADF fraction. The ADF fraction contained a significant amount of amino acids accounting for 9.3–32.7% of the ADF (by weight). The presence of amino acids in the ADF fraction means that using ADF to estimate insect chitin results in an overestimation of insect chitin content. Using ADF adjusted for its amino acid content, the estimated chitin content of these insect species ranged from 2.7–49.8 mg/kg (as is) and 11.6–137.2 mg/kg (dry matter basis). Additionally, these data suggest that for the species measured here the amount of chitin nitrogen is quite small (as a % of total nitrogen) and that crude protein (nitrogen × 6.25) provides a reasonable estimate of the true protein for most species of insects. Zoo Biol 0:1–11, 2007. © 2007 Wiley-Liss, Inc.
351 citations
TL;DR: Utilizing a collection of chitin/polysaccharide deacetylase deletion strains, it is determined that during vegetative growth, chitosan helps to maintain cell integrity and aids in bud separation.
Abstract: Cryptococcus neoformans is an opportunistic fungal pathogen that causes cryptococcal meningoencephalitis, particularly in immunocompromised patients. The fungal cell wall is an excellent target for antifungal therapies as it is an essential organelle that provides cell structure and integrity, it is needed for the localization or attachment of known virulence factors, including the polysaccharide capsule, melanin, and phospholipase, and it is critical for host-pathogen interactions. In C. neoformans, chitosan produced by the enzymatic removal of acetyl groups from nascent chitin polymers has been implicated as an important component of the vegetative cell wall. In this study, we identify four putative chitin/polysaccharide deacetylases in C. neoformans. We have demonstrated that three of these deacetylases, Cda1, Cda2, and Cda3, can account for all of the chitosan produced during vegetative growth in culture, but the function for one, Fpd1, remains undetermined. The data suggest a model for chitosan production in vegetatively growing C. neoformans where the three chitin deacetylases convert chitin generated by the chitin synthase Chs3 into chitosan. Utilizing a collection of chitin/polysaccharide deacetylase deletion strains, we determined that during vegetative growth, chitosan helps to maintain cell integrity and aids in bud separation. Additionally, chitosan is necessary for maintaining normal capsule width and the lack of chitosan results in a “leaky melanin” phenotype. Our analysis indicates that chitin deacetylases and the chitosan made by them may prove to be excellent antifungal targets.
314 citations
TL;DR: At least three pathways co‐ordinated by the PKC, HOG MAP kinase and Ca2+/calcineurin signalling pathways co-ordinated chitin synthesis and activation of chit in synthesis operates at both transcriptional and post‐transcriptional levels.
Abstract: Chitin is an essential component of the fungal cell wall and its synthesis is under tight spatial and temporal regulation. The fungal human pathogen Candida albicans has a four member chitin synthase gene family comprising of CHS1 (class II), CHS2 (class I), CHS3 (class IV) and CHS8 (class I). LacZ reporters were fused to each CHS promoter to examine the transcriptional regulation of chitin synthesis. Each CHS promoter had a unique regulatory profile and responded to the addition of cell wall damaging agents, to mutations in specific CHS genes and exogenous Ca2+. The regulation of both CHS gene expression and chitin synthesis was co-ordinated by the PKC, HOG MAP kinase and Ca2+/calcineurin signalling pathways. Activation of these pathways also resulted in increased chitin synthase activity in vitro and elevated cell wall chitin content. Combinations of treatments that activated multiple pathways resulted in synergistic increases in CHS expression and in cell wall chitin content. Therefore, at least three pathways co-ordinately regulate chitin synthesis and activation of chitin synthesis operates at both transcriptional and post-transcriptional levels.
278 citations
TL;DR: To characterize alpha-chitin nanocrystals produced from shrimp shells in regard to crystallite properties and the specific surface area of the chitin nanoparticles, X-ray diffraction data indicate an increase in chit in crystallinity after hydrolysis, as less-ordered chitIn domains are digested.
274 citations
TL;DR: The authors analyzed the expression patterns of Arabidopsis thaliana transcription factor and ubiquitin-ligase genes in response to purified chitooctaose at different treatment times (15, 30, 60, 90, and 120 min after treatment).
Abstract: Chitin, found in the cell walls of true fungi and the exoskeleton of insects and nematodes, is a well-established elicitor of plant defense responses. In this study, we analyzed the expression patterns of Arabidopsis thaliana transcription factor (TF) and ubiquitin-ligase genes in response to purified chitooctaose at different treatment times (15, 30, 60, 90, and 120 min after treatment), using both quantitative polymerase chain reaction and the Affymetrix Arabidopsis whole-genome array. A total of 118 TF genes and 30 ubiquitin-ligase genes were responsive to the chitin treatment. Among these genes, members from the following four TF families were overrepresented: APETALA2/ethylene-reponsive element binding proteins (27), C2H2 zinc finger proteins (14), MYB domain-containing proteins (11), and WRKY domain transcription factors (14). Transcript variants from a few of these genes were found to respond differentially to chitin, suggesting transcript-specific regulation of these TF genes.
TL;DR: The spray could be used as a first-aid tool on bleeding abrasions; the gel enhanced physiological repair and was recommended for areas with thin epidermal layers, and the gauze was found to be superior to other dressings insofar as no scar remained.
TL;DR: While the longevity of the SEM was relatively short in these studies, it is possible to increase operation times by controlling particle size, mass, and type of material needed to achieve desired power levels that could theoretically be sustained over periods of years or even decades.
Abstract: A sediment microbial fuel cell (MFC) produces electricity through the bacterial oxidation of organic matter contained in the sediment. The power density is limited, however, due in part to the low organic matter content of most marine sediments. To increase power generation from these devices, particulate substrates were added to the anode compartment. Three materials were tested: two commercially available chitin products differing in particle size and biodegradability (Chitin 20 and Chitin 80) and cellulose powder. Maximum power densities using chitin in this substrate-enhanced sediment MFC (SEM) were 76 ± 25 and 84 ± 10 mW/m2 (normalized to cathode projected surface area) for Chitin 20 and Chitin 80, respectively, versus less than 2 mW/m2 for an unamended control. Power generation over a 10 day period averaged 64 ± 27 mW/m2 (Chitin 20) and 76 ± 15 mW/m2 (Chitin 80). With cellulose, a similar maximum power was initially generated (83 ± 3 mW/m2), but power rapidly decreased after only 20 h. Maximum powe...
TL;DR: In this article, the effect of solvent composition and temperature on chitin structure was investigated with an optical microscope, from which 8 Wt% NaOH/4 Wt % urea concentrations were deduced as suitable and −20°C as the appropriate temperature.
TL;DR: It is demonstrated that Schiff base cross-linked chitosan fibrous mats can be produced utilizing a one-step electrospinning process that is 25 times faster and, therefore, more economical than a previously reported two-step vapor-cross-linking method.
TL;DR: In histological findings, collagen fibers run perpendicular against the incisional line in the oligosaccharide group (NACOS, COS), and many activated fibroblasts were observed around the wound in the chitosan group, where the higher the deacetylation degree becomes, the more the stronger the break strength becomes.
TL;DR: It was found that B. subtilis produced sufficient quantities of acid to remove the minerals from the shell and to prevent spoilage organisms and the protease enzyme in Bacillus species was responsible for the deprotenisation of the shell.
TL;DR: It is found that chitin linked to β(1‐6)glucan is diminished in mutants of the CRH1 or theCRH2/UTR2 gene and completely absent in a double mutant, which indicates that Crh1p and Crh2p, homologues of glycosyltransferases, ferry chitIn chains from chit in synthase III to β (1‐ 6) glucan.
Abstract: In budding yeast, chitin is found in three locations: at the primary septum, largely in free form, at the mother-bud neck, partially linked to beta(1-3)glucan, and in the lateral wall, attached in part to beta(1-6)glucan. By using a recently developed strategy for the study of cell wall cross-links, we have found that chitin linked to beta(1-6)glucan is diminished in mutants of the CRH1 or the CRH2/UTR2 gene and completely absent in a double mutant. This indicates that Crh1p and Crh2p, homologues of glycosyltransferases, ferry chitin chains from chitin synthase III to beta(1-6)glucan. Deletion of CRH1 and/or CRH2 aggravated the defects of fks1Delta and gas1Delta mutants, which are impaired in cell wall synthesis. A temperature shift from 30 degrees C to 38 degrees C increased the proportion of chitin attached to beta(1-6)glucan. The expression of CRH1, but not that of CRH2, was also higher at 38 degrees C in a manner dependent on the cell integrity pathway. Furthermore, the localization of both Crh1p and Crh2p at the cell cortex, the area where the chitin-beta(1-6)glucan complex is found, was greatly enhanced at 38 degrees C. Crh1p and Crh2p are the first proteins directly implicated in the formation of cross-links between cell wall components in fungi.
TL;DR: A detailed study of the structural and physico-chemical properties of skeletal fragments of the glass sponge Farrea occa shows that these fibres have a layered design with specific compositional variations in the chitin/silica composite, the first report of a silica-chitin's composite biomaterial found in nature.
Abstract: Sponges (Porifera) are presently gaining increased scientific attention because of their secondary metabolites and specific skeleton structures. In contrast to demosponges, whose skeletons are formed from biopolymer spongin, glass sponges (hexactinellids) possess silica-organic composites as the main natural material for their skeletal fibres. Chitin has a crystalline structure and it constitutes a network of organized fibres. This structure confers rigidity and resistance to organisms that contain it, including monocellular (yeast, amoeba, diatoms) and multicellular (higher fungi, arthropods, nematodes, molluscs) organisms. In contrast to different marine invertebrates whose exoskeletons are built of chitin, this polysaccharide has not been found previously as an endogenous biopolymer within glass sponges (Hexactinellida). We hypothesized that glass sponges, which are considered to be the most basal lineage of multicellular animals, must possess chitin. Here, we present a detailed study of the structural and physico-chemical properties of skeletal fragments of the glass sponge Farrea occa. We show that these fibres have a layered design with specific compositional variations in the chitin/silica composite. We applied an effective approach for the demineralization of glass sponge skeletal formations based on an etching procedure using alkali solutions. The results show unambiguously that alpha-chitin is an essential component of the skeletal structures of Hexactinellida. This is the first report of a silica-chitin's composite biomaterial found in nature. From this perspective, the view that silica-chitin scaffolds may be key templates for skeleton formation also in ancestral unicellular organisms, rather than silica-protein composites, emerges as a viable alternative hypothesis.
TL;DR: Both chitins (bumblebee and shrimp) exhibited identical spectra, while the bumblebee chitin had a 5% lower degree of acetylation and was characterized by a fine membrane texture.
TL;DR: The results suggested that acetylated chitosan (chitin) fibers were more biodegradable than chitOSan and the biodegradation rate of chitin fiber can be controlled to desirable extent by the variation of acetylation degree.
Abstract: In the present study, we investigated the biodegradation of the fibers of chitosan and its acetylated derivatives in vitro and in vivo. A series of chitosan fibers, with acetylation degrees of 7.7%, 21.6%, 40.9%, 61.2%, 82.5% and 93.4%, were obtained by acetylating chitosan filament with acetic anhydride, and were investigated by FT-IR analysis, elemental analysis and scanning electron microscopy analysis. The in vitro experimental data indicated that the degradation rate of chitosan fiber was strongly dependent on the degree of acetylation, and the degradation rate increased with an enhancement of the acetylation degree of chitosan fibers. In vivo degradation experiment evaluated by light microscopy as well as scanning electron microscopy, was studied by implanting the fibers between the two nerve stumps of the rat sciatic nerve gap (6 months). The findings demonstrated that acetylation degree could influence the degradation rate of chitosan fibers in vivo. These results suggested that acetylated chitosan (chitin) fibers were more biodegradable than chitosan and the biodegradation rate of chitin fiber can be controlled to desirable extent by the variation of acetylation degree.
TL;DR: Modified chitin could be suitable in a column system for dye pre-concentration as well as wastewater minimisation, and the column study showed that modified chit in could be used for more than four cycles of adsorption and elution by distilled water.
TL;DR: This pilot study tested the gastric juices of 25 Italian subjects on the artificial substrates 4-methylumbelliferyl-β-D-N,N’,diacetylchitobiose or/and fluorescein isothiocyanate (FITC) to demonstrate the presence of a chitinase activity and confirmed that this activity was characteristic of AMCase.
Abstract: Chitin digestion by humans has generally been questioned or denied. Only recently chitinases have been found in several human tissues and their role has been associated with defense against parasite i
TL;DR: The aim of this paper is the study of the interaction between chitosan powder and various kinds of pathogen microorganisms potentially present in water.
Abstract: Chitosan, the deacetylated derivative of chitin, is a natural D-glucosamine polymer that can be extracted from the shells of seafood such as prawns crabs and lobsters. It can be used as a flocculent, plant disease resistant promoter, anti-cancer agent, wound healing promotion agent and antimicrobial agent. The aim of this paper is the study of the interaction between chitosan powder and various kinds of pathogen microorganisms potentially present in water. First of all, physico-chemical characterisations of chitin and chitosan powder were performed. The deacetylation yields were 35 %, 60 % and 80 ± 10 %. The experimental studies focused on the measurements of the mortality constant rate for various bacterial strains, Escherichia coli, Pseudomonas aeruginosa, Enterococcus faecalis and Staphylococcus saprophyticus. An explanation of the antibacterial mechanisms is proposed involving the cell wall disruption due to free amino groups present in chitosan.
TL;DR: This work has found that the chitin disaccharide GlcNAc could be completely hydrolyzed to the monosaccharides Glc NAc with negligible concomitant de-N-acetylation, and the ch itin disachcharide and monosACcharide were further used to study the depolymerization reaction and the de- N- acetylation reaction, respectively.
TL;DR: Chitin is identified in the prismatic layer of the Japanese pearl oyster with a combination of Calcofluor White staining with IR and NMR spectral analyses and a cDNA encoding chitin synthase (PfCHS1) is cloned, contributing to the formation of the framework for calcification in the shell.
Abstract: The shell of the Japanese pearl oyster, Pinctada fucata, consists of two layers, the prismatic layer on the outside and the nacreous layer on the inside, both of which comprise calcium carbonate and organic matrices. Previous studies indicate that the nacreous organic matrix of the central layer of the framework surrounding the aragonite tablet is β-chitin, but it remains unknown whether organic matrices in the prismatic layer contain chitin or not. In the present study, we identified chitin in the prismatic layer of the Japanese pearl oyster, Pinctada fucata, with a combination of Calcofluor White staining with IR and NMR spectral analyses. Furthermore, we cloned a cDNA encoding chitin synthase (PfCHS1) that produces chitin, contributing to the formation of the framework for calcification in the shell.
TL;DR: The increase in viscosity of chitosan nanoscaffold as compared to that of the chitin whiskers suggests that the scaffold network performs as a polymer bulk in the solution.
TL;DR: In this article, the authors used chitin whiskers as nanofiller to improve the dimensional stability of a silk fibroin sponge by incorporating them into the sponges.
TL;DR: In this paper, the authors investigated the effect of chitin hydrolysates on the apoptosis of CT26 cells in a concentration and time-dependent manner, and found that the hydrolysate of water-soluble chitosan (A, B and C) inhibited the survival of CT 26 cells.
TL;DR: A chitinase encoding gene from Bacillus sp.