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Study of the antibacterial effects of chitosans on bacillus cereus (and its spores) by atomic force microscopy imaging and nanoindentation

Fernandes, João C.; Eaton, Peter; Gomes, Ana M.; Pintado, Manuela E.; Malcata, F. Xavier
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
Publicado em //2009 ENG
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Bacillus cereus is a Gram-positive, spore-forming bacterium that is widely distributed in nature. Its intrinsic thermal resistance coupled with the extraordinary resistance against common food preservation techniques makes it one of the most frequent food-poisoning microorganisms causing both intoxications and infections. In order to control B. cereus growth/sporulation, and hence minimize the aforementioned hazards, several antimicrobial compounds have been tested. The aim of this work was to assess by atomic force microscopy (AFM) the relationship between the molecular weight (MW) ofchitosan and its antimicrobial activity upon both vegetative and resistance forms of B. cereus. The use ofAFM imaging studies helped us to understand how chitosans with different MW act differently upon B. cereus. Higher MW chitosans (628 and 100 kDa) surrounded both forms of B. cereus cells by forming a polymer layer-which eventually led to the death of the vegetative form by preventing the uptake of nutrients yet did not affect the spores since these can survive for extended periods without nutrients. Chitooligosaccharides (COS) (<3kDa), on the other hand, provoked more visible damages in the B. cereus vegetative form-most probably due to the penetration of the cells by the COS. The use of COS by itself on B. cereus spores was not enough for the destruction ofa large number of cells...

Antimicrobial effects of chitosans and chitooligosaccharides, upon Staphylococcus aureus and Escherichia coli, in food model systems

Fernandes, João C.; Tavaria, Freni K.; Soares, José C.; Ramos, Óscar S.; Monteiro, M. João; Pintado, Manuela E.; Malcata, F. Xavier
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
Publicado em //2008 ENG
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The objective of this study was to elucidate the controversial relationship between the molecular weight (MW) of chitosans and their antibacterial activity (upon different inoculum levels, at several concentrations). The influence of food components on the activity was also ascertained, as well as acceptance by a sensory panel. All the compounds tested exhibited antibacterial activity against Staphylococcus aureus and Escherichia coli. This activity was shown to be closely dependent on the inoculum level, MW and concentration used. Within 4 h at 10³ cells/mL, all five compounds, at every concentration (0.5%, 0.25% and 0.1%, w/v), proved to be bactericidal; for higher inocula, 0.1% (w/v) was only bacteriostatic; at 107 or 105 cells/mL, and independently of the inoculum level, 0.25% (w/v) of any chitooligosaccharide (COS) mixture was sufficient to reduce the E. coli initial population by at least 3 log cycles; COS never exhibited bactericidal action over S. aureus, unlike high and medium MW chitosans—which, at 0.5% (w/v), presented a bactericidal effect even against 107 cells/mL. When incorporated in liquid food matrices, medium and high MW chitosans maintained their activity, for both matrices and bacteria, although a slower activity was noticeable in milk; however...

Atomic force microscopy study of the antibacterial effects of chitosans on Escherichia coli and Staphylococcus aureus

Eaton, Peter; Fernandes, João C.; Pereira, Eulália; Pintado, Manuela E.; Malcata, F. Xavier
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
Publicado em //2008 ENG
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Chitosan has been reported to be a non-toxic, biodegradable antibacterial agent. The aim of this work was to elucidate the relationship between the molecular weight of chitosan and its antimicrobial activity upon two model microorganisms, one Gram-positive (Staphylococcus aureus) and one Gramnegative (Escherichia coli). Atomic force microscopy (AFM) imaging was used to obtain high-resolution images of the effect of chitosans on the bacterial morphology. The AFM measurements were correlated with viable cell numbers, which show that the two species reacted differently to the high- and lowmolecular-weight chitosan derivatives. The images obtained revealed not only the antibacterial effects, but also the response strategies used by the bacteria; cell wall collapse and morphological changes reflected cell death, whereas clustering of bacteria appeared to be associated with cell survival. In addition, nanoindentation experiments with the AFM revealed mechanical changes in the bacterial cell wall induced by the treatment. The nanoindentation results suggested that despite little modification observed in the Gram-positive bacteria in morphological studies, cell wall damage had indeed occurred, since cell wall stiffness was reduced after chitooligosaccharide treatment.

Influence of chitooligosaccharide derivatives obtained by Maillard reaction on the growth of probiotic bacteria

Cardelle-Cobas, A.; Martins, M.; Gullón, B.; Gullón, P.; Tavaria, Freni; Pintado, M. E.
Fonte: Universidade Católica Portuguesa Publicador: Universidade Católica Portuguesa
Tipo: Conferência ou Objeto de Conferência
Publicado em //2012 ENG
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Synthesis and characterization of new oligosaccharides with prebiotic activity

Montenegro, Maria Inês Pereira
Fonte: Universidade Católica Portuguesa Publicador: Universidade Católica Portuguesa
Tipo: Dissertação de Mestrado
Publicado em 31/01/2014 ENG
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A relevância da microbiota intestinal na manutenção da saúde do hospedeiro é bem conhecida e, nas últimas décadas, a consciencialização dos consumidores para a escolha de alimentos saudáveis tem vindo a aumentar. Existem diversas estratégias para estimular a proliferação de bactérias intestinais benéficas, incluindo o consumo de prebióticos. Atualmente, existe uma vasta gama de hidratos de carbono prebióticos no mercado, a maior parte isolados de polissacarídeos de plantas, de que são exemplo a inulina e frutooligossacarídeos (FOS). No entanto, existe um interesse crescente no desenvolvimento de novos prebióticos com funcionalidade adicional. Nesse sentido, o quitosano, sendo um polissacarídeo composto por unidades de glucosamina (GlcN) e N-acetil glucosamina (GlcNAc) unidas por ligações β (1→4), apresenta uma estrutura muito semelhante à dos atuais prebióticos glucooligossacarídeos. A diferença principal consiste na presença de grupos amina na sua estrutura, que lhe confere uma importante atividade antimicrobiana. A modificação química do quitosano por substituição dos seus grupos amina poderia eliminar este efeito antimicrobiano e converter o quitosano num novo e interessante ingrediente prebiótico. Assim...

The common nodABC genes of Rhizobium meliloti are host-range determinants

Roche, Philippe; Maillet, Fabienne; Plazanet, Claire; Debellé, Frédéric; Ferro, Myriam; Truchet, Georges; Promé, Jean-Claude; Dénarié, Jean
Fonte: The National Academy of Sciences of the USA Publicador: The National Academy of Sciences of the USA
Tipo: Artigo de Revista Científica
Publicado em 24/12/1996 EN
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Symbiotic bacteria of the genus Rhizobium synthesize lipo-chitooligosaccharides, called Nod factors (NFs), which act as morphogenic signal molecules on legume hosts. The common nodABC genes, present in all Rhizobium species, are required for the synthesis of the core structure of NFs. NodC is an N-acetylglucosaminyltransferase, and NodB is a chitooligosaccharide deacetylase; NodA is involved in N-acylation of the aminosugar backbone. Specific nod genes are involved in diverse NF substitutions that confer plant specificity. We transferred to R. tropici, a broad host-range tropical symbiont, the ability to nodulate alfalfa, by introducing nod genes of R. meliloti. In addition to the specific nodL and nodFE genes, the common nodABC genes of R. meliloti were required for infection and nodulation of alfalfa. Purified NFs of the R. tropici hybrid strain, which contained chitin tetramers and were partly N-acylated with unsaturated C16 fatty acids, were able to elicit nodule formation on alfalfa. Inactivation of the R. meliloti nodABC genes suppressed the ability of the NFs to nodulate alfalfa. Studies of NFs from nodA, nodB, nodC, and nodI mutants indicate that (i) NodA of R. meliloti, in contrast to NodA of R. tropici...

Homologs of the Xenopus developmental gene DG42 are present in zebrafish and mouse and are involved in the synthesis of Nod-like chitin oligosaccharides during early embryogenesis.

Semino, C E; Specht, C A; Raimondi, A; Robbins, P W
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em 14/05/1996 EN
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The Xenopus developmental gene DG42 is expressed during early embryonic development, between the midblastula and neurulation stages. The deduced protein sequence of Xenopus DG42 shows similarity to Rhizobium Nod C, Streptococcus Has A, and fungal chitin synthases. Previously, we found that the DG42 protein made in an in vitro transcription/translation system catalyzed synthesis of an array of chitin oligosaccharides. Here we show that cell extracts from early Xenopus and zebrafish embryos also synthesize chitooligosaccharides. cDNA fragments homologous to DG42 from zebrafish and mouse were also cloned and sequenced. Expression of these homologs was similar to that described for Xenopus based on Northern and Western blot analysis. The Xenopus anti-DG42 antibody recognized a 63-kDa protein in extracts from zebrafish embryos that followed a similar developmental expression pattern to that previously described for Xenopus. The chitin oligosaccharide synthase activity found in extracts was inactivated by a specific DG42 antibody; synthesis of hyaluronic acid (HA) was not affected under the conditions tested. Other experiments demonstrate that expression of DG42 under plasmid control in mouse 3T3 cells gives rise to chitooligosaccharide synthase activity without an increase in HA synthase level. A possible relationship between our results and those of other investigators...

Biosynthesis of lipooligosaccharide nodulation factors: Rhizobium NodA protein is involved in N-acylation of the chitooligosaccharide backbone.

Röhrig, H; Schmidt, J; Wieneke, U; Kondorosi, E; Barlier, I; Schell, J; John, M
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em 12/04/1994 EN
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Rhizobium meliloti interacts symbiotically with alfalfa by forming root nodules in which the bacteria fix nitrogen. The Rhizobium nodulation genes nodABC are involved in the synthesis of lipooligosaccharide symbiotic signal molecules, which are mono-N-acylated chitooligosaccharides. These bacterial signals elicit nodule organogenesis in roots of legumes. To elucidate the role of the NodA protein in lipooligosaccharide biosynthesis, we prepared a radiolabeled tetrasaccharide precursor carrying an amino group as a potential attachment site for N-acylation at the nonreducing glucosamine residue. Various criteria demonstrate that NodA is involved in the attachment of a fatty acyl chain to this tetrasaccharide precursor, yielding a biologically active nodulation factor.

Biosynthesis of Rhizobium meliloti lipooligosaccharide Nod factors: NodA is required for an N-acyltransferase activity.

Atkinson, E M; Palcic, M M; Hindsgaul, O; Long, S R
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em 30/08/1994 EN
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Rhizobium bacteria synthesize N-acylated beta-1,4-N-acetylglucosamine lipooligosaccharides, called Nod factors, which act as morphogenic signal molecules to legume roots during development of nitrogen-fixing nodules. The biosynthesis of Nod factors is genetically dependent upon the nodulation (nod) genes, including the common nod genes nodABC. We used the Rhizobium meliloti NodH sulfotransferase to prepare 35S-labeled oligosaccharides which served as metabolic tracers for Nod enzyme activities. This approach provides a general method for following chitooligosaccharide modifications. We found nodAB-dependent conversion of N-acetylchitotetraose (chitotetraose) monosulfate into hydrophobic compounds which by chromatographic and chemical tests were equivalent to acylated Nod factors. Sequential incubation of labeled intermediates with Escherichia coli containing either NodA or NodB showed that NodB was required before NodA during Nod factor biosynthesis. The acylation activity was sensitive to oligosaccharide chain length, with chitotetraose serving as a better substrate than chitobiose or chitotriose. We constructed a putative Nod factor intermediate, GlcN-beta 1,4-(GlcNAc)3, by enzymatic synthesis and labeled it by NodH-mediated sulfation to create a specific metabolic probe. Acylation of this oligosaccharide required only NodA. These results confirm previous reports that NodB is an N-deacetylase and suggest that NodA is an N-acyltransferase.

Rhizobium NodB protein involved in nodulation signal synthesis is a chitooligosaccharide deacetylase.

John, M; Röhrig, H; Schmidt, J; Wieneke, U; Schell, J
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em 15/01/1993 EN
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The common nodulation genes nodABC are conserved in all rhizobia and are involved in synthesis of a lipooligosaccharide signal molecule. This bacterial signal consists of a chitooligosaccharide backbone, which carries at the nonreducing end a fatty acyl chain. The modified chitooligosaccharide molecule triggers development of nodules on the roots of the leguminous host plant. To elucidate the specific role of the NodB protein in nodulation factor synthesis, we have purified recombinant NodB and determined its biochemical role by direct assays. Our data show that the NodB protein of Rhizobium meliloti deacetylates the nonreducing N-acetylglucosamine residue of chitooligosaccharides. The monosaccharide N-acetylglucosamine is not deacetylated by NodB. In the pathway of Nod factor synthesis, deacetylation at the nonreducing end of the oligosaccharide backbone may be a necessary requirement for attachment of the fatty acyl chain.

The primary structure of a fungal chitin deacetylase reveals the function for two bacterial gene products.

Kafetzopoulos, D; Thireos, G; Vournakis, J N; Bouriotis, V
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em 01/09/1993 EN
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Chitin deacetylase (EC 3.5.1.41) hydrolyzes the N-acetamido groups of N-acetyl-D-glucosamine residues in chitin. A cDNA to the Mucor rouxii mRNA encoding chitin deacetylase was isolated, characterized, and sequenced. Protein sequence comparisons revealed significant similarities of the fungal chitin deacetylase to rhizobial nodB proteins and to an uncharacterized protein encoded by a Bacillus stearothermophilus open reading frame. These data suggest the functional homology of these evolutionarily distant proteins. NodB is a chitooligosaccharide deacetylase essential for the biosynthesis of the bacterial nodulation signals, termed Nod factors. The observed similarity of chitin deacetylase to the B. stearothermophilus gene product suggests that this gene encodes a polysaccharide deacetylase.

Rhizobial NodL O-Acetyl Transferase and NodS N-Methyl Transferase Functionally Interfere in Production of Modified Nod Factors

López-Lara, Isabel M.; Kafetzopoulos, Dimitris; Spaink, Herman P.; Thomas-Oates, Jane E.
Fonte: American Society for Microbiology Publicador: American Society for Microbiology
Tipo: Artigo de Revista Científica
Publicado em /06/2001 EN
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The products of the rhizobial nodulation genes are involved in the biosynthesis of lipochitin oligosaccharides (LCOs), which are host-specific signal molecules required for nodule formation. The presence of an O-acetyl group on C-6 of the nonreducing N-acetylglucosamine residue of LCOs is due to the enzymatic activity of NodL. Here we show that transfer of the nodL gene into four rhizobial species that all normally produce LCOs that are not modified on C-6 of the nonreducing terminal residue results in production of LCOs, the majority of which have an acetyl residue substituted on C-6. Surprisingly, in transconjugant strains of Mesorhizobium loti, Rhizobium etli, and Rhizobium tropici carrying nodL, such acetylation of LCOs prevents the endogenous nodS-dependent transfer of the N-methyl group that is found as a substituent of the acylated nitrogen atom. To study this interference between nodL and nodS, we have cloned the nodS gene of M. loti and used its product in in vitro experiments in combination with purified NodL protein. It has previously been shown that a chitooligosaccharide N deacetylated on the nonreducing terminus (the so-called NodBC metabolite) is the preferred substrate for NodS as well as for NodL. Here we show that the NodBC metabolite...

Binding Site for Chitin Oligosaccharides in the Soybean Plasma Membrane1

Day, R. Bradley; Okada, Mitsuo; Ito, Yuki; Tsukada, Koji; Zaghouani, Habib; Shibuya, Naoto; Stacey, Gary
Fonte: American Society of Plant Physiologists Publicador: American Society of Plant Physiologists
Tipo: Artigo de Revista Científica
Publicado em /07/2001 EN
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Affinity cross-linking of the plasma membrane fraction to an 125I-labeled chitin oligosaccharide led to the identification and characterization of an 85-kD, chitin binding protein in plasma membrane-enriched fractions from both suspension-cultured soybean cells and root tissue. Inhibition analysis indicated a binding preference for larger (i.e. degrees of polymerization = 8) N-acetylated chitin molecules with a 50% inhibition of initial activity value of approximately 50 nm. N-Acetyl-glucosamine and chitobiose showed no inhibitory effects at concentrations as high as 250 μm. It is noteworthy that the major lipo-chitin oligosaccharide Nod signal produced by Bradyrhizobium japonicum was also shown to be a competitive inhibitor of ligand binding. However, the binding site appeared to recognize the chitin portion of the Nod signal, and it is unlikely that this binding activity represents a specific Nod signal receptor. Chitooligosaccharide specificity for induction of medium alkalinization and the generation of reactive oxygen in suspension-cultured cells paralleled the binding activity. Taken together, the presence of the chitin binding protein in the plasma membrane fraction and the specificity and induction of a biological response upon ligand binding suggest a role for the protein as an initial response mechanism for chitin perception in soybean (Glycine max).

Genomic Analysis and Initial Characterization of the Chitinolytic System of Microbulbifer degradans Strain 2-40

Howard, Michael B.; Ekborg, Nathan A.; Taylor, Larry E.; Weiner, Ronald M.; Hutcheson, Steven W.
Fonte: American Society for Microbiology Publicador: American Society for Microbiology
Tipo: Artigo de Revista Científica
Publicado em /06/2003 EN
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The marine bacterium Microbulbifer degradans strain 2-40 produces at least 10 enzyme systems for degrading insoluble complex polysaccharides (ICP). The draft sequence of the 2-40 genome allowed a genome-wide analysis of the chitinolytic system of strain 2-40. The chitinolytic system includes three secreted chitin depolymerases (ChiA, ChiB, and ChiC), a secreted chitin-binding protein (CbpA), periplasmic chitooligosaccharide-modifying enzymes, putative sugar transporters, and a cluster of genes encoding cytoplasmic proteins involved in N-acetyl-d-glucosamine (GlcNAc) metabolism. Each chitin depolymerase was detected in culture supernatants of chitin-grown strain 2-40 and was active against chitin and glycol chitin. The chitin depolymerases also had a specific pattern of activity toward the chitin analogs 4-methylumbelliferyl-β-d-N,N′-diacetylchitobioside (MUF-diNAG) and 4-methylumbelliferyl-β-d-N,N′,N"-triacetylchitotrioside (MUF-triNAG). The depolymerases were modular in nature and contained glycosyl hydrolase family 18 domains, chitin-binding domains, and polycystic kidney disease domains. ChiA and ChiB each possessed polyserine linkers of up to 32 consecutive serine residues. In addition, ChiB and CbpA contained glutamic acid-rich domains. At 1...

Lipo-chitooligosaccharide Nodulation Signals from Rhizobium meliloti Induce Their Rapid Degradation by the Host Plant Alfalfa.

Staehelin, C.; Schultze, M.; Kondorosi, E.; Kondorosi, A.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /08/1995 EN
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Extracellular enzymes from alfalfa (Medicago sativa L.) involved in the degradation of nodulation (Nod) factors could be distinguished by their different cleavage specificities and were separated by lectin affinity chromatography. A particular glycoprotein was able to release an acylated lipo-disaccharide from all tested Nod factors having an oligosaccharide chain length of four or five residues. Structural modifications of the basic lipo-chitooligosaccharide did not affect the cleavage site and had only weak influence on the cleavage efficiency of Nod factors tested. The acylated lipo-trisaccharide was resistant to degradation. When alfalfa roots were preincubated with Nod factors at nanomolar concentrations, the activity of the dimer-forming enzyme was stimulated up to 6-fold within a few hours. The inducing activity of Nod factors decreased in the order NodRm-IV(C16:2,Ac,S) > NodRm-IV(C16:2,S) and NodRm-V(C16:2,Ac,S) > NodRm-V(C16:2,S) > NodRm-IV(C16:0,S) > NodRm-IV(C16:2). Pretreatment with NodRm-III(C16:2) as well as unmodified chitooligosaccharides did not stimulate the dimer-forming enzyme. Roots preincubated with Rhizobium meliloti showed similar stimulation of the dimer-forming activity. Mutant strains unable to produce Nod factors did not enhance the hydrolytic activity. These results indicate a rapid feedback inactivation of Nod signals after their perception by the host plant alfalfa.

A LysM Receptor-Like Kinase Plays a Critical Role in Chitin Signaling and Fungal Resistance in Arabidopsis[W][OA]

Wan, Jinrong; Zhang, Xue-Cheng; Neece, David; Ramonell, Katrina M.; Clough, Steve; Kim, Sung-yong; Stacey, Minviluz G.; Stacey, Gary
Fonte: American Society of Plant Biologists Publicador: American Society of Plant Biologists
Tipo: Artigo de Revista Científica
Publicado em /02/2008 EN
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Chitin, a polymer of N-acetyl-d-glucosamine, is found in fungal cell walls but not in plants. Plant cells can perceive chitin fragments (chitooligosaccharides) leading to gene induction and defense responses. We identified a LysM receptor-like protein (LysM RLK1) required for chitin signaling in Arabidopsis thaliana. The mutation in this gene blocked the induction of almost all chitooligosaccharide-responsive genes and led to more susceptibility to fungal pathogens but had no effect on infection by a bacterial pathogen. Additionally, exogenously applied chitooligosaccharides enhanced resistance against both fungal and bacterial pathogens in the wild-type plants but not in the mutant. Together, our data indicate that LysM RLK1 is essential for chitin signaling in plants (likely as part of the receptor complex) and is involved in chitin-mediated plant innate immunity. The LysM RLK1-mediated chitin signaling pathway is unique, but it may share a conserved downstream pathway with the FLS2/flagellin- and EFR/EF-Tu–mediated signaling pathways. Additionally, our work suggests a possible evolutionary relationship between the chitin and Nod factor perception mechanisms due to the similarities between their potential receptors and between the signal molecules perceived by them.

Caught at its own game: regulatory small RNA inactivated by an inducible transcript mimicking its target

Figueroa-Bossi, Nara; Valentini, Martina; Malleret, Laurette; Bossi, Lionello
Fonte: Cold Spring Harbor Laboratory Press Publicador: Cold Spring Harbor Laboratory Press
Tipo: Artigo de Revista Científica
Publicado em 01/09/2009 EN
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A relevant, yet little recognized feature of antisense regulation is the possibility of switching roles between regulatory and regulated RNAs. Here we show that induction of a Salmonella gene relies on the conversion of a small RNA from effector to regulatory target. The chiP gene (formerly ybfM), identified and characterized in the present study, encodes a conserved enterobacterial chitoporin required for uptake of chitin-derived oligosaccharides. In the absence of inducer, chiP is kept silent by the action of a constitutively made small RNA, ChiX (formerly SroB, RybC), which pairs with a sequence at the 5′ end of chiP mRNA. Silencing is relieved in the presence of chitooligosaccharides due to the accumulation of an RNA that pairs with ChiX and promotes its degradation. Anti-ChiX RNA originates from an intercistronic region of the chb operon, which comprises genes for chitooligosaccharide metabolism and whose transcription is activated in the presence of these sugars. We present evidence suggesting that the chb RNA destabilizes ChiX sRNA by invading the stem of its transcription terminator hairpin. Overall, our findings blur the distinction between effector and target in sRNA regulation, raising the possibility that some of the currently defined targets could actually be inhibitors of sRNA function.

Modulation of lipid metabolism by mixtures of protamine and chitooligosaccharide through pancreatic lipase inhibitory activity in a rat model

Kang, Nam-Hee; Lee, Won Kyung; Yi, Bo-Rim; Park, Min-Ah; Lee, Hye-Rim; Park, Sang-Ki; Hwang, Kyung-A; Park, Hyoung Kook; Choi, Kyung-Chul
Fonte: Korean Association for Laboratory Animal Science Publicador: Korean Association for Laboratory Animal Science
Tipo: Artigo de Revista Científica
EN
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Overweight and obesity are usually related with high fat and calorie intake, and seriously causative of lifestyle-related diseases such as cardiovascular disorders, arteriosclerosis, and colon cancer. In this study, we propose a novel dietary therapy against overweight and obesity using mixtures of protamine and chitooligosaccharide (COS), which are known to interrupt the lipid metabolism in the body. Protamine is a dietary protein originated from salmon reproductive organ, and COS is an oligosaccharide made from chitin or chitosan by chemical or enzymatic hydrolysis. In the enzyme activity analysis in vitro, protamine and COS strongly suppressed the activity of pancreatic lipase, which is the primary enzyme for the digestion and absorption of lipids in the intestine. In in vivo animal test, the mixtures of protamine and COS significantly reduced the serum levels of triglyceride (TG), total cholesterol (T-CHO), and low density lipoprotein-cholesterol (LDLC) and inhibited the accumulation of lipids in liver tissue of Sprague Dawley (SD) rats fed high fat diets. On the other hand, they increased fecal TG and T-CHO contents. From these alterations in lipid metabolism, we verified that protamine and COS mixtures could effectively interrupt the digestion and absorption of dietary lipids in the body by inhibiting pancreatic lipase activity. In addition...

Chitooligosaccharide Induces Mitochondrial Biogenesis and Increases Exercise Endurance through the Activation of Sirt1 and AMPK in Rats

Jeong, Hyun Woo; Cho, Si Young; Kim, Shinae; Shin, Eui Seok; Kim, Jae Man; Song, Min Jeong; Park, Pil Joon; Sohn, Jong Hee; Park, Hyon; Seo, Dae-Bang; Kim, Wan Gi; Lee, Sang-Jun
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Publicado em 11/07/2012 EN
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27.44%
By catabolizing glucose and lipids, mitochondria produce ATPs to meet energy demands. When the number and activity of mitochondria are not sufficient, the human body becomes easily fatigued due to the lack of ATP, thus the control of the quantity and function of mitochondria is important to optimize energy balance. By increasing mitochondrial capacity? it may be possible to enhance energy metabolism and improve exercise endurance. Here, through the screening of various functional food ingredients, we found that chitooligosaccharide (COS) is an effective inducer of mitochondrial biogenesis. In rodents, COS increased the mitochondrial content in skeletal muscle and enhanced exercise endurance. In cultured myocytes, the expression of major regulators of mitochondrial biogenesis and key components of mitochondrial electron transfer chain was increased upon COS treatment. COS-mediated induction of mitochondrial biogenesis was achieved in part by the activation of silent information regulator two ortholog 1 (Sirt1) and AMP-activated protein kinase (AMPK). Taken together, our data suggest that COS could act as an exercise mimetic by inducing mitochondrial biogenesis and enhancing exercise endurance through the activation of Sirt1 and AMPK.

Downregulation of CD147 by chitooligosaccharide inhibits MMP-2 expression and suppresses the metastatic potential of human gastric cancer

LUO, ZHIGUO; DONG, XIAOXIA; KE, QING; DUAN, QIWEN; SHEN, LI
Fonte: D.A. Spandidos Publicador: D.A. Spandidos
Tipo: Artigo de Revista Científica
EN
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Metastasis is considered to be the major cause of mortality in patients with cancer, and gastric cancer is a highly metastatic cancer. In the present study, the anti-metastatic activity of chitooligosaccharide (COS) in human gastric cancer cells and its underlying mechanism were investigated. It was found that COS significantly inhibited SGC-7901 cell proliferation and metastasis in a dose-dependent manner, as observed by MTT, wound-healing and Transwell assays. Quantitative real-time polymerase chain reaction and western blot analysis indicated that COS could decrease the expression of cluster of differentiation 147 (CD147) and subsequently reduce matrix metalloproteinase-2 (MMP-2) expression. A clear dose-dependent inhibition of MMP-2 activity was also observed in SGC-7901 cells following treatment with COS in gelatin zymography experiments. Furthermore, overexpression of CD147 (when transfected with pEGFP-C1 plasmid) in SGC-7901 cells partially protected against COS-induced inhibition of MMP-2. The results of the present study demonstrated the potential of COS in suppressing gastric cancer metastasis, and that the CD147/MMP-2 pathway may be involved as the key mechanism of its anti-metastatic effect.