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See detailChitin biodegradation in marine environments : an experimental approach
Poulicek, Mathieu ULg; Jeuniaux, Charles ULg

in Biochemical systematics and ecology (1991), 19(5), 385-394

Chitin biomasses and production in marine environments are quite high. Planktonic biocenoses arte the main producers and one should expect that sediments, mainly organoclastic ones, will constitute some ... [more ▼]

Chitin biomasses and production in marine environments are quite high. Planktonic biocenoses arte the main producers and one should expect that sediments, mainly organoclastic ones, will constitute some kind of reserve compartment for the biogeochemical cycle of this polymer. In fact, this is not the case. The low chitin biomass in most marine sediments can only be explained if chitin is weathered at the same rate as it is produced. In order to test this hypothesis, we developed an experimental approach to chitin biodegradation in marine environments. In open water conditions, zooplanktonic remains are first degraded by autolytic processes making most organic compounds readily susceptible for further hydrolysis by extrinsic decomposers. Different populations (with high densities and various hydrolytic potentials) follow each other. The sequence of hydrolyc activities optimizes the recycling of most detritic compounds including nearly 90% of the chitin produced. At sediment-water interface, the remaining material appears to be pulvirized and incorporated into the aerobic sedimentary layers while the decomposer community changes once again. Sediment chitinoclasts are opportunistic and densities react quickly to chitin input. In sediments, oxic and anoxic, chitin appears essentially present in the form of chitinoproteic matrices inside mineralized skeletons. A rich population of microborers develops on these matrices by secreting extracellular hydrolases. Densities of microborers of 250-450 * 10 3 cm-2 are currently encountered. Anaerobic decomposers are more adapted to refractory compounds than aerobic ones. This leads to a nearly complete mineralization of the chitinoproteic matrices embedded in the biotic sedimentary layers (more than 90% of the chitin weathered within less than two years). [less ▲]

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See detailChitin biomass and production in the marine environment
Jeuniaux, Charles ULg; Voss-Foucart, Marie Françoise

in Biochemical Systematics & Ecology (1991), 19(5), 347-356

The total production nof chitin has been tentatively calculated on the basis of original analytical data on chitin in zooplankton and in benthic communities growing on experimental substrates studied in ... [more ▼]

The total production nof chitin has been tentatively calculated on the basis of original analytical data on chitin in zooplankton and in benthic communities growing on experimental substrates studied in the Mediterranean Sea, together with data in the literature dealing with total and exuviae production by krill and by some large crustacean species. It appears that crustaceans are the main chitin producers both in planktonic and benthic ecosystems, and that mean total production of chitin in the whole marine biocycle is at least of 2,3 billion metric tons per year. [less ▲]

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See detailChitin biomass in marine sedimenis
Poulicek, Mathieu ULg; Jeuniaux, Charles ULg

Scientific conference (1988)

One hundred marine sediments of various origins were screened in order to evaluate their chitin biomass. Our purpose was to assess the detritic chitin stocks in order to find some potential new source of ... [more ▼]

One hundred marine sediments of various origins were screened in order to evaluate their chitin biomass. Our purpose was to assess the detritic chitin stocks in order to find some potential new source of chitin. The chitin biomass of marine sediments is very diversified, from 2 up to 2 800 ug g-1 decalcified sediment (DS). Most sediments have low or very low chitin biomass (67 % under 100 ug g-1 DS). Nosignificant difference related to depth nor climatic influence was found except that all sediments richer in chitin (above 300 ug g-1 DS) are on the continental shelf (above 200 m depth). Actually, the chitin content is higher in coarse, much calcified sediments of organoclastic origin ; bryozoa and shelly sands and gravels are the richest. The [less ▲]

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See detailChitin biomass in marine sediments
Poulicek, Mathieu ULg; Jeuniaux, Charles ULg

in Skjak-Braek, A. (Ed.) Chitin and Chitosan (1988)

One hundred marine sediments of various origins were screened in order to evaluate their chitin biomass. Our purpose was to assess the detritic chitin stocks in order to find some potential new source of ... [more ▼]

One hundred marine sediments of various origins were screened in order to evaluate their chitin biomass. Our purpose was to assess the detritic chitin stocks in order to find some potential new source of chitin. The chitin biomass of marine sediments is very diversified, from 2 up to 2800 ug g-1 decalcified sediment (DS). Most sediments have low or very low chitin biomass (67% under 100 ug g-1 DS). No significant difference relmated to depth nor climatic influence was found except that all sediments richer in chitin (above 300 ug g-1 DS) are on the continental shelf (above 200m dephth). Actually, the chitin content is highter in coarse, much calcified sediments of organoclastic origin ; bryozoa and shelly sands and gravels are the richest. The powerful hydrolytic activity of microorganisms lower the steady state equilibrium level between chitin input and weathering, so most "unprotected" chitin is weathered very soon after settling. Marine sediments appears thus as a non comprtitive potential industrial chitin source. [less ▲]

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See detailChitin in biogeochemical cycles : Abstract 202
Jeuniaux, Charles ULg; Seki, H.

Conference (1990, August)

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See detailChitin location and subcellular organization during heterologous expression of chitin deacetylase in yeast Pichia pastoris
Jaspar-Versali, Marie-France ULg; Aifa, Karim; Compère, Philippe ULg et al

in Domard, Alain; Jeuniaux, Charles; Muzzarelli, Ricardo (Eds.) et al Advances in chitin sciences, volume I (1996)

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See detailChitin production by animals and natural communities in marine environment
Jeuniaux, Charles ULg; Bussers, Jean-Claude ULg; Voss-Foucart, M.F. et al

in Muzzarelli, R.; Jeuniaux, Charles; Gooday, G.W. (Eds.) Chitin in nature and technology (1986)

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See detailChitin-glucan complex production by Komagataella pastoris: downstream optimization and product characterization
Farinha, Inês; Duarte, Paulo; Pimentel, Ana et al

in Carbohydrate Polymers (2015), 130

Purified chitin-glucan complex (CGCpure) was extracted from Komagataella pastoris biomass using a hot alkaline treatment, followed by neutralization and repeated washing with deionised water. The co ... [more ▼]

Purified chitin-glucan complex (CGCpure) was extracted from Komagataella pastoris biomass using a hot alkaline treatment, followed by neutralization and repeated washing with deionised water. The co-polymer thus obtained had a glucan:chitin molar ratio of 75:25 and low protein and inorganic salts contents (3.0 and 0.9 wt%, respectively). CGCpure had an average molecular weight of 4.9 × 105 Da with a polydispersity index of 1.7, and a crystallinity index of 50%. Solid-state NMR provided structural insight at the co-polymer. X-ray diffraction and FTIR analysis suggest that CGCpure has b-chitin in its structure. CGCpure presented an endothermic decomposition peak at 315 oC, assigned to the degradation of the saccharide structures. This study revealed that K. pastoris CGC has properties similar to other chitinous biopolymers and may represent an attractive alternative to crustacean chitin derived-products, being a reliable raw material for the development of new/improved pharmaceutical, cosmetic or food products. [less ▲]

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See detailChitin-Glucan, a natural cell scaffold for skin rejuvenation: in vivo safety and efficacy.
Gautier, S.; Xhauflaire-Uhoda, Emmanuelle; Gonry, P. et al

in International Journal of Cosmetic Science (2008), 30

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See detailChitinase : an addition to the list of hydrolases in the digestive tract of vertebrates
Jeuniaux, Charles ULg

in Nature (1961), 192(4798), 135-136

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See detailChitinase et bactéries chitinolytiques dans le tube digestif d'un cloporte (Porcellio Scaber Latr.) (Isope, Oniscide)
Jeuniaux, Charles ULg

in Archives Internationales de Physiologie et de Biochimie (1956), 64(4), 583-586

Le tube digestif de Porcellio scaber Latr. (Isope Oniscide) contient une chitinase. Il héberge une flore bactérienne chitinolytique quantitativement plus abondante que celle du milieu extérieur et ... [more ▼]

Le tube digestif de Porcellio scaber Latr. (Isope Oniscide) contient une chitinase. Il héberge une flore bactérienne chitinolytique quantitativement plus abondante que celle du milieu extérieur et qualitativement différente. Ces bactéries chitinolytiques pourraient être responsables de l'élaboration de la chitinase du cloporte. [less ▲]

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See detailLa chitinase exuviale des Insectes
Jeuniaux, Charles ULg

in Mémoires de la Société Royale d'Entomologie de Belgique (1955), 27

1. Il est prouvé que le liquide exuvial des Insectes, sécrété peu avant la mue, contient une chitinase. Celle-ci dissout une partie importante des strates internes de la vieille cuticule (endocuticule ... [more ▼]

1. Il est prouvé que le liquide exuvial des Insectes, sécrété peu avant la mue, contient une chitinase. Celle-ci dissout une partie importante des strates internes de la vieille cuticule (endocuticule). Chez Platysamia cecropia L., le liquide exuvial est d'abord sécrété sous forme de gel, inactif au point de vue enzymatique. 2. Les extraits aqueux d'exuvies larvaires et nymphales sont doués de propriétés chitinolytiques, dues à la présence de liquide exuvial adhérent à la surface interne des exuvies. Certaines exuvies, telles que celles des nymphes de Tenebrio et des larves de Carausius, sont particulièrement riches en chitinase exuviale. 3. Chez toutes les espèces d'Insectes étudiées jusqu'à présent, on a pu mettre en évidence l'intervention d'une chitinase au moment de la mue. 4. La cinétique de la chitinase des exuvies ou du liquide exuvial de Bombyx mori et de Tenebrio molitor est identique, et ne diffère guère de celle des autres chitinases connues (pH optimum : entre 4.9 et 5.5 ; température optimale : 37° C.). [less ▲]

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See detailChitinases
Jeuniaux, Charles ULg

in Archives Internationales de Physiologie et de Biochimie (1958), 29(522), 644-650

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See detailChitinases et chitobiases dans les tissus épidermiques, l'hépatopancréas et le tube digestif du crabe
Jeuniaux, Charles ULg

in Archives Internationales de Physiologie et de Biochimie (1960), 68(4), 684-685

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See detailChitine "libre" et chitine "masquée" dans les structures squelettiques d'Invertébrés
Jeuniaux, Charles ULg

in Archives Internationales de Physiologie et de Biochimie (1964), 72(2), 329-330

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See detailLa chitine dans le règne animal
Jeuniaux, Charles ULg

in Bulletin de la Société Zoologique de France (1982), 107(3), 363-386

Chitin, a high linear polymer composed of N-acetylglucosamine residues attached by B-1,4 glycosidic linkages, is often used in the animal kingdom as an organic support of cuticular and exoskeletal ... [more ▼]

Chitin, a high linear polymer composed of N-acetylglucosamine residues attached by B-1,4 glycosidic linkages, is often used in the animal kingdom as an organic support of cuticular and exoskeletal structures. A specific enzymatic method allows the detection and quantitative measurement of chitin, and may be suitable for pointing out the existence of some linkage to other constituents ("free" and "bound" chitin). Chitin is mainly organised, at the ultrastructural level, in microfibrils (glycoprotein complex). Chitin is a constituent of diverse structures, built up by Protozoa, mainly Ciliates (kystic membranes, sheaths). In Diblastic Metazoa, chitin is secreted by the ectoderm of most Hydrozoa and of some Octocorallia and Scyphozoa, but is completely lacking in Porifera and Ctenophora. Among Triblastic Metazoa, chitin is frequently secreted by the ectoderm of Spiralia, as well Pseudocoelomates (mainly in egg envelopes) as Protostomian Coelomates (in cuticles, shells, setae, operculae, scales, spicules, etc.), with the exception of Sipunculida. Chitin does not seem to be secreted at all by Acoelomates. Peritrophic membranes of Arthropoda and Annelida seem to be of endodermic origin, as well as different types of cuticular formations in the stomach of many Molluscs. Chitin is a frequent constituent of ectodermic productions in Lophophorates (tubes, ectocyst, shells), in Pogonophora (tubes) and in Chaetognatha. The secretion of this polysaccharide is entirely lacking in Echinoderms, Stomochordates and Chordates, with the remarkable exception of the peritrophic membrane in Tunicates. Chitin biosynthesis thus appears as a biochemical characteristic, which must be used with care when discussing the systematic position and phylogenetic relationships. [less ▲]

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See detailChitine et phylogénie : application d'une méthode enzymatique de dosage de la chitine
Jeuniaux, Charles ULg

in Bulletin de la Société de Chimie Biologique (1965), 47(12), 2267-2278

Using a purified preparation of chitinases, an enzymatic method for the specific detection and the quantitative measurement of chitin is described. This method allows the determination of the free chitin ... [more ▼]

Using a purified preparation of chitinases, an enzymatic method for the specific detection and the quantitative measurement of chitin is described. This method allows the determination of the free chitin and of the chitin bound to other substances, as in glycoproteic complexes. This method has been applied to the study of chitin distribution in the animal kingdom. On the basis of this survey, the evolution of chitin biosynthesis is discussed from the point of view of animal phylogeny. [less ▲]

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See detailChitinolytic enzymes of the gastric mucosa of Perodicticus Potto (Primate Prosimian) : purification and enzyme specificity
Cornelius, C.; Dandrifosse, Guy ULg; Jeuniaux, Charles ULg

in International Journal of Biochemistry (The) (1976), 7

1. Enzymatic extracts of Perodicticus potto gastric mucosa showed chitinolytic activity together with lysozymic activity. 2. After purification by adsortion on colloidal chitin and gel chromatography, an ... [more ▼]

1. Enzymatic extracts of Perodicticus potto gastric mucosa showed chitinolytic activity together with lysozymic activity. 2. After purification by adsortion on colloidal chitin and gel chromatography, an enzymatic preparation with high chitinolytic activity was devoid of any lysozymic activity. 3. The gastric chitinolytic enzymes of Perodicticus potto are thus "true" chitinases specific of the B-1,4-N-acetylglucosamine linkages in chitin molecule. [less ▲]

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See detailChitinoproteic complexes and mineralization in mollusk skeletal structures
Poulicek, Mathieu ULg; Voss-Foucart, M.F.; Jeuniaux, Charles ULg

in Muzzarelli, R.; Jeuniauc, Charles (Eds.) Chitin in nature and technology (1986)

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