scispace - formally typeset
Search or ask a question

Showing papers on "Chitin published in 1986"


Journal ArticleDOI
18 Jul 1986-Cell
TL;DR: Three CHS1 gene disruption experiments were performed, demonstrating that strains with the disrupted gene have a recognizable phenotype, lack measurable chitin synthase activity in vitro but are viable, contain normal levels of chitIn in vivo, and mate and sporulate efficiently.

257 citations



Journal ArticleDOI
TL;DR: Production of chitobiase (N-acetylglucosaminidase) was enhanced from high basal levels by amino sugars, but was less inducible and less susceptible to catabolite repression than chitinase.
Abstract: Summary: Synthesis of chitinase and chitosanase by the entomopathogenic fungus Metarhizium anisopliae is regulated by products of chitin and chitosan degradation through an inducer-repressor mechanism. Slow-feeding with sugars or alanine (about 20 μg ml−1 h−1) in a carbon deficient medium to prevent catabolite repression (restricted cultures) demonstrated that the most effective inducers of chitinase and chitosanase were the principal monomeric constituents of chitin (N-acetylglucosamine) and chitosan (glucosamine) respectively. Increasing the rate of release of N-acetylglucosamine decreased chitinase synthesis by about 87% while causing a sevenfold increase in growth. In batch cultures high chitinase activities were present only in chitin-containing medium. There was a negative correlation between accessibility and amount of chitin substrates, levels of free N-acetylglucosamine in culture fluids and chitinase production. Addition of carbohydrates, lipid or proteins to chitin-grown cultures repressed chitinase production. Basal levels of chitinase were produced in non-inducing media. Production of chitobiase (N-acetylglucosaminidase) was enhanced from high basal levels by amino sugars, but was less inducible and less susceptible to catabolite repression than chitinase.

175 citations


Journal ArticleDOI
TL;DR: Extracellular fluids from Metarhizium anisopliae, Beauveria bassiana, and Verticillium lecanii grown on cuticle as the sole carbon source released amino acids and N-acetylglucosamine from protein and chitin, respectively, in comminuted locust cuticle, suggesting that cuticular chit in is shielded by protein.

168 citations


Book ChapterDOI
01 Jan 1986
TL;DR: Data is reviewed which partially explains the paradoxical action of chitosan which at similar concentrations can completely inhibit all RNA synthesis in some fungal organisms and thus suppress gene activity.
Abstract: The regulatory role of chitosan in eucaryotic organisms may have far reaching consequences because chitosan and its acetylated form, chitin, are prevalent in nature. We have found two different regulatory functions for chitosan in a simple fungal-plant interaction1. Chitosan which is a normal component of the cell walls of some fungi (Fig. 1) can activate specific genes in plants and at similar concentrations can completely inhibit all RNA synthesis in some fungal organisms and thus suppress gene activity. In this paper we review data which partially explains this paradoxical action.

156 citations


Journal ArticleDOI
TL;DR: This finding, together with the apparent zymogenic nature of Chs2, is consistent with the hypothesis, previously put forward for Chs1, that localized deposition of chitin is attained by activation of the zymogen form at a specific time and place.

156 citations


Book ChapterDOI
01 Jan 1986
TL;DR: The antifungal effect of chitin was indirect, via antagonistic soil microorganisms, and suppressed total fungal population and stimulated lytic and antibiotic-producing microorganisms such as actinomycetes.
Abstract: The antifungal effect of chitin has been demonstrated in field experiments. A marked reduction of root-rot in beans and of vascular wilt in radishes, both caused by Fusarium spp., were observed subsequent to addition of chitin to soil (1). Chitin amendment suppressed total fungal population and stimulated lytic and antibiotic-producing microorganisms such as actinomycetes (2–4). The antifungal effect of chitin thus was indirect, via antagonistic soil microorganisms.

143 citations


Journal ArticleDOI
TL;DR: It is suggested that the hydroxyl groups of C-3 and C-6 positions are equally substituted with the phosphate group, which means that chitin phosphates (P-chitins) are easily soluble in water independent of DS, while DA-ch itins of high DS are insoluble in water owing to the amphoteric property, while those of low DS are water soluble.

111 citations



Journal ArticleDOI
TL;DR: The lectin wheat germ agglutinin (WGA) has a binding site which is able to bind a sequence of three N-acetyl-glucosamine residues, therefore, it has a very strong affinity for the polymers of this sugar, especially chitin.
Abstract: The lectin wheat germ agglutinin (WGA) has a binding site which is able to bind a sequence of three N-acetyl-glucosamine residues. Therefore, it has a very strong affinity for the polymers of this sugar, especially chitin. Colloidal gold can be labelled with WGA and used as a specific electron-dense marker for the electron-microseopic localization of chitin. The specificity of the WGA-gold binding can be checked by competitive inhibition with 5–10 mM triacetyl chitotriose. The reliability of this method was tested in three species. In the formation zone of the radula of the snail, Biomphalaria glabrata Say, chitin or chitin precursors were localized in vesicles of the odontoblasts, outside the extremely long microvilli of odontoblasts and in the newly formed teeth. The inner peritrophic envelope of the earwig, Forficula auricularia L., is characterized by an orthognal texture of bundles of microfibrils that are thought to contain chitin. The pesence of chitin was proved using the present method. In the peritrophic membranes of the blowfly, Calliphora erythrocephala Meigen, it was possible to differentiate between chitin and glycoproteins which have N-acetylglucosamine residues.

89 citations


Journal ArticleDOI
TL;DR: Water-soluble chitin was successfully crosslinked to varying extents with glutaraldehyde in homogeneous aqueous solutions to improve the properties as an adsorbent for metal cations, and the effects of crosslinking were discussed.
Abstract: Water-soluble chitin was successfully crosslinked to varying extents with glutaraldehyde in homogeneous aqueous solutions to improve the properties as an adsorbent for metal cations, and the effects of crosslinking were discussed. Complete insolubilization was achieved with the fivefold excess aldehyde, but, in terms of adsorptivity of Cu2+, the chitin crosslinked at an aldehyde/amino group ratio of 1.0 was found to exhibit remarkable capacity and was much superior to others. The desorption of Cu2+ from the adsorption complex was also attained effectively at pH 2.0. These results indicated that the loose crosslinking was quite simple and efficient to produce high capacity adsorbents for practical use. Thermal behavior of the crosslinked chitin was examined by TMA and TGA; a softening phenomenon was observed at 145°C.

Patent
18 Jul 1986
TL;DR: In this article, the introduction of DNA encoding for the production of chitinase, an enzyme capable of degrading Chitin present in fungi and nematodes, was described.
Abstract: Novel bacteria strains are decribed which are created by the introduction of DNA encoding for the production of chitinase, an enzyme capable of degrading chitin present in fungi and nematodes. The strains have utility in producing chitinase for the purpose of inhibiting plant pathogens. Novel pathogen-resistant plants are also described which are created by introduction of DNA encoding for the production of chitinase.

Journal ArticleDOI
TL;DR: X-ray diffraction analysis of chitin synthesized in the presence of Calcofluor revealed the absence of crystallinity as long as the material was kept in wet conditions, and results strongly suggest the existence of a gap between polymerization and crystallization of Chitin chains.
Abstract: Chitin synthase activity of membrane preparations from hyphae of Schizophyllum commune was strongly inhibited by added chitinase because chitin immediately after its synthesis was highly susceptible to chitinase. In the absence of synthesis, chitin became more resistant to chitinase with time. Chitin synthesized in the presence of the optical brightener Calcofluor White M2R was extremely susceptible to degradation by chitinase and this susceptibility was maintained for a long time. X-ray diffraction analysis of chitin synthesized in the presence of Calcofluor revealed the absence of crystallinity as long as the material was kept in wet conditions. After drying, discrete deflections characteristic for α-chitin appeared concomitant with a decrease in the susceptibility for chitinase. These results strongly suggest the existence of a gap between polymerization and crystallization of chitin chains.

Book ChapterDOI
Keisuke Kurita1
TL;DR: Chitin can be regarded as a new type of polymeric material having greater possibilities than cellulose in many respects as discussed by the authors, since it is an amino polysaccharide, it is capable of undergoing many additional modification reactions.
Abstract: Although chitin may be less advanced than cellulose with regard to research and utilization, it has recently begun to attract much attention in both basic and applied research fields, including not only biology and biochemistry but also organic and polymer chemistry, pharmacology, and medicine. The number of reports and patents is increasing at a remarkable rate. Besides basic research, many attempts have been made to find new applications for chitin. Further basic studies, however, seem to be necessary to realize its full potential. One possible breakthrough in chitin chemistry and technology is the development of chemical modifications of chitin which are being studied more and more actively to explore highly sophisticated functions. Chitin can be regarded as a new type of polymeric material having greater possibilities than cellulose in many respects. Since it is an amino polysaccharide, chitin is capable of undergoing many additional modification reactions. It is anticipated that widespread applications will be found in the near future.

Journal ArticleDOI
TL;DR: The observation that the stable isotope ratios of chitin from crustacean exoskeletons recovered from archaeological sites with ages up to 1400 years bp are in good agreement with measurements on modern crustaceans from similar environments is illustrated.

Journal ArticleDOI
TL;DR: It is shown that chitin prepared from alkali- and heat-treated insect or crab cuticle contains trace levels of deacetylated residues that are released as a dead-end product, N-monoacetylchitobiose, after digestion by the binary enzyme system.

Journal ArticleDOI
TL;DR: Combinations of agents active against cell wall synthesis in fungi may prove more useful as chemotherapeutic agents than such compounds used singly, according to checkerboard determinations.
Abstract: Combinations of nikkomycin X (NX) or nikkomycin Z (NZ), known inhibitors of chitin synthesis in fungi, together with papulacandin B (PB), an inhibitor of beta-glucan synthesis, were tested for synergistic activity against four isolates of Candida albicans by using the broth microdilution checkerboard technique and a method to assess the regeneration of cell wall material in protoplasts. The construction of isobolograms from the data generated by the checkerboard determinations revealed a synergistic effect for the two classes of compounds against all strains. The combination of NX and PB was more effective than the combination of NZ and PB, perhaps reflecting the lower Ki value of NX. While the presence of NX and NZ reduced chitin synthesis, as determined by staining with calcofluor white and assaying with a microfluorimeter, cells treated with PB demonstrated an increased synthesis of chitin. Protoplast regeneration experiments using similar concentrations of the two classes of compounds resulted in comparable findings. The combination of NX and PB resulted in a greater inhibition of chitin synthesis than did equivalent combinations of NZ and PB. These data suggest that combinations of agents active against cell wall synthesis in fungi may prove more useful as chemotherapeutic agents than such compounds used singly.

Journal ArticleDOI
TL;DR: Extension of the standard extraction procedure for phytoplankton photosynthetic carbon pools shows the presence of chitin (poly N- acetyl- d -glucosamine) in the previously considered protein pool, which has been previously characterized solely as the “protei” fraction.

Journal ArticleDOI
TL;DR: The results demonstrated that the morphological alterations caused by polyoxin D were due to the absence of chitin, a wall component important for formation of primary septa and for maintenance of structural integrity during morphogenesis.
Abstract: Summary: Yeasts and mycelia of the pathogen Candida albicans grown in the presence of polyoxin D, a competitive inhibitor of chitin synthase, formed chains of swollen bulbous cells as observed by fluorescence microscopy. Wheat germ agglutinin (WGA) complexed to colloidal gold (Au) was used as a specific label at the ultrastructural level to visualize chitin in walls of control and polyoxin-treated cells. In control cells, Au-WGA labelling was preferentially localized in the innermost wall layers and was predominant at bud scars and septa. After 4·5 h in 4 mM-polyoxin D, budding in yeasts and lateral wall growth in mycelia continued, but primary septa failed to form and no Au-WGA labelling was detected in the walls. These results demonstrated that the morphological alterations caused by polyoxin D were due to the absence of chitin, a wall component important for formation of primary septa and for maintenance of structural integrity during morphogenesis.

Journal ArticleDOI
TL;DR: The soil isolate Cellvibrio mixtus UQM2294 degraded a variety of polysaccharides including microcrystalline cellulose and polygalacturonic acid, and the genes for starch, carboxymethyl cellulose, cellobiose, chitin, and pectin hydrolysis were subcloned.
Abstract: The soil isolate Cellvibrio mixtus UQM2294 degraded a variety of polysaccharides including microcrystalline cellulose. Among 6,000 cosmid clones carrying C. mixtus DNA, constructed in Escherichia coli with pHC79, 50 expressed the ability to degrade one or more of the following substrates: carboxymethyl cellulose, chitin, pectin (polygalacturonic acid), cellobiose, and starch. These degradative genes are encoded in a single 94.1-kilobase segment of the C. mixtus genome; a preliminary order of the genes is starch hydrolysis, esculin hydrolysis, cellobiose utilization, chitin hydrolysis, carboxymethyl cellulose hydrolysis, and polygalacturonic acid hydrolysis. A restriction endonuclease cleavage map was constructed, and the genes for starch, carboxymethyl cellulose, cellobiose, chitin, and pectin hydrolysis were subcloned.

Journal ArticleDOI
TL;DR: In laboratory experiments, zoospores of Rhizophlyctis rosea accumulated and encysted on cellulose but not on chitin (crab shell) ‘baits’, suggesting that surface recognition events mediate zoospore accumulation.
Abstract: In laboratory experiments, zoospores of Rhizophlyctis rosea accumulated and encysted on cellulose (transparent film, lens tissue and filter paper) but not on chitin (crab shell) ‘baits’. Zoospores of Chytridium confervae, Pythium aphanidermatum and a Saprolegnia sp. accumulated on chitin but not on cellulose. Zoospores of Allomyces arbuscula, Pythium graminicola and other fungi accumulated on both cellulose and chitin, whereas spores of some fungi, e.g. P. oligandrum , did not accumulate on cellulose or chitin. Initial contact of zoospores with these materials occurred at random, not by taxis, but was followed by characteristic behavioural changes of the zoospores. Zoospore accumulation could be reduced or prevented by prior treatment of cellulose or chitin with dyes or a lectin, suggesting that surface recognition events mediate zoospore accumulation.

Journal ArticleDOI
TL;DR: The potential exists for the production of chitosans with tailored physico-chemical properties from “waste” chitin and the degree of acetylation of commercial crab shell chitOSan was reduced.
Abstract: Highly deacetylated chitosan was accumulated in the mycelia ofMucorrouxii orPhycomycesblakesleeanus. These cultures also effected the deacetylation of the chitin ofAspergillusniger mycelium into chitosan. After 96 hours of incubation with these cultures the degree of acetylation of commercial crab shell chitosan was reduced from 25.0% to values between 4.3 and 8.6%. The potential exists for the production of chitosans with tailored physico-chemical properties from “waste” chitin.

Book ChapterDOI
01 Jan 1986
TL;DR: In this paper, the stable isotope ratios 13C/12C and 15N/14N in chitin and chitosan isolates show large variations which reflect intrinsic compositional and isotopic heterogeneities as well as differences caused by preparation.
Abstract: Measurements of the stable isotope ratios 13C/12C and 15N/14N in chitin and chitosan isolates show large variations which reflect intrinsic compositional and isotopic heterogeneities as well as differences caused by methods of preparation. Analysis of D-glucosamine hydrochloride from chitin hydrolysates eliminates these problems.

Patent
17 Jan 1986
TL;DR: Ester-stabilized chitin polymers as discussed by the authors are a type of polymers which have been made from a naturally occurring calcified chitIN/protein matrix, and which are useful in processes requiring consistent, reproduceable structure.
Abstract: Ester-stabilized chitin polymers which have been dissociated and purified from a naturally occurring calcified chitin/protein matrix, and which substantially retain the structural features of the chitin matrix in that they comprise elongated fibers which are rapidly and quantitatively recognized by enzymes specific for naturally occurring chitin. The chitin polymers are made by a method in which the naturally occurring matrix is first decalcified and deproteinized, and then the chitin is dispersed and stabilized in a cold dilute ester-forming acid before being recovered. The polymers are useful in processes requiring consistent, reproduceable structure. Polymers having these useful attributes are particularly identifiable by their ability to react with enzymes specific for naturally occurring chitin.

Book ChapterDOI
01 Jan 1986
TL;DR: In this article, deacetylated chitin derivatives such as 70% deacetlyated chtin (DAC-70) and 30% of deacetyylated Chitin (30% DAC-30) were shown to have potent immunological activities for activation of peritoneal macrophages in vivo, suppression of Meth-A tumor cells in syngeneic BALB/c mice and stimulation of non-specific host resistance against Escherichia coli infection in mice.
Abstract: Previously, we have reported the immunological activities of chitin derivatives for the stimulation of non-specific host resistance in mice.1 Among derivatives of chitin tested, deacetylated chtin derivatives such as 70% deacetylated chitin (DAC-70) and 30% deacetylated chitin (DAC-30) were shown to have potent immunological activities for activation of peritoneal macrophages in vivo, suppression of Meth-A tumor cells in syngeneic BALB/c mice and stimulation of non-specific host resistance against Escherichia coli infection in mice. Recently, Suzuki et al.2,3 have reported that chitin and chitosan were effective for the protection of host against infection with Candida albicans and Staphylococcus aureus and against growth of Ehrlich and Sarcoma 180 ascites tumor.

Patent
10 Dec 1986
TL;DR: In this paper, the water-soluble chitin-oligomers were obtained in improved yields, when finely ground chitins were mixed with a concentrated hydrohalogenic acid containing a particular proportion of the hydrogen halide per a unit quantity of the chitIN under the irradiation with ultrasonic waves and also under the agitation by mechanical stirrer, followed by hydrolyzing the chitsin in the resulting homogeneous mixture comprising the n-acetyl-chitin and the concentrated HOG acid while further continuously irradiated with the ultrasonic wave and
Abstract: Tetra-N-acetyl-chitotetraose, penta-N-acetylchitopentaose and hexa-N-acetyl-chitohexaose, ones of the water-soluble chitin-oligomers, may be obtained in improved yields, when finely ground chitin is quickly and intimately mixed with a concentrated hydrohalogenic acid containing a particular proportion of the hydrogen halide per a unit quantity of the chitin under the irradiation with ultrasonic waves and also under the agitation by mechanical stirrer, followed by hydrolyzing the chitin in the resulting homogeneous mixture comprising the chitin and the concentrated hydrohalogenic acid while said homogeneous mixture is further continuously irradiated with the ultrasonic waves and also agitated by the mechanical stirrer. From the aqueous phase of the hydrolyzed reaction mixture are recovered the desired water-soluble chitin-oligomers which are each useful as an immunopotentiating, antitumor agent or antifungal, antibacterial agent.

Patent
09 Apr 1986
TL;DR: In this article, a process for recovering chitin and possibly astaxanthin from chitins is described, by demineralization with an acid and removal of protein using the enzymatic activity of fish viscera.
Abstract: A process according to which chitin and possibly astaxanthin are recovered from chitin sources, particularly shrimp and krill shells, by demineralization with an acid and removal of protein using the enzymatic activity of fish viscera. The chitin-decomposing enzymatic activity of the fish viscera is suppressed by treatment of the viscera with acid at pH 1.2 to 2.5, preferably 1.5 to 2.5, prior to or during the removal of protein. The recovering may be effected in the presence of an oil, preferably from cod liver, extracting the astaxanthin.

Journal ArticleDOI
TL;DR: Eight strains of obligately anaerobic, mesophilic, chitinolytic bacteria were isolated from the sediment of an estuarine environment and hydrolysis of chitin proceeded at a relatively low rate and was incomplete.
Abstract: Eight strains of obligately anaerobic, mesophilic, chitinolytic bacteria were isolated from the sediment of an estuarine environment. The isolates were rod-shaped, Gram-negative, and formed terminal spherical spores that swelled the sporangium. The major products from the fermentation of chitin were: acetate, ethanol, formate, CO2, H2 and ammonia. Growth of the isolates was possible at pH values ranging from 5.0–9.0. During the fermentation of chitin, N-acetylglucosamine accumulated in the culture fluids and was not metabolized. No organic compounds other than chitin and its oligomers could be demonstrated to support growth of the isolates. Hydrolysis of chitin proceeded at a relatively low rate and was incomplete. Approximately 65% of the initial amount of chitin was hydrolyzed during a period of 5–10 days. Supplementation of the medium with yeast extract, casamino acids or peptone did not enhance the rate of chitin hydrolysis, but reducing agents such as Na2S2O4 and Ti (III)-NTA markedly stimulated the rate of chitin fermentation. The ecological implications of the high degree of substrate specialization are discussed.

Journal ArticleDOI
TL;DR: This study describes an in-vitro assay for estimating numbers of Candida albicans adherent to mouse intestinal mucosa and found that chitin soluble extracts inhibited adhesion of the yeasts to duodenal tissue by 48% and 43%, respectively.
Abstract: This study describes an in-vitro assay for estimating numbers of Candida albicans adherent to mouse intestinal mucosa No significant differences were observed in the capacity of C albicans to adhere to genetically distinct mouse strains nor in the binding ability of three C albicans strains Chitin soluble extracts, prepared from chitin isolated from C albicans or from chitin obtained commercially, inhibited adhesion of the yeasts to duodenal tissue by 48% and 43%, respectively

Book ChapterDOI
01 Jan 1986
TL;DR: While the proposed uses of chitosan in medicine are numerous, no applications in dentistry have been reported so far, due to the characteristics of the oral cavity, where various bacteria are constantly present and where lysozyme, a chitin degrading enzyme, occurs in the salivary secretion.
Abstract: While the proposed uses of chitosan in medicine are numerous (1 – 7), no applications in dentistry have been reported so far. This might be due to the characteristics of the oral cavity, where various bacteria are constantly present and where lysozyme, a chitin degrading enzyme, occurs in the salivary secretion.