Induction Of Chitinase Research Articles

Chitinase induction in Trichoderma harzianum: a solid-state fermentation approach using shrimp waste and wheat bran/commercial chitin for chitooligosaccharides synthesis

This study innovatively employed solid-state fermentation (SSF) to evaluate chitinase induction in Trichoderma harzianum. Solid-state fermentation minimizes water usage, a crucial global resource, and was applied using shrimp waste chitin and a mixture of commercial chitin with wheat bran as substrates. Shrimp waste and wheat bran were pretreated and characterized for SSF, and the fungus’s utilization of the substrates was assessed using spectrophotometric and microscopic methods. The resulting enzymes’ ability to produce chitooligosaccharides (COS) mixtures was studied. Wheat bran/commercial chitin demonstrated superior performance, with a 1.8-fold increase in chitinase activity (76.3 U/mg protein) compared to shrimp waste chitin (41.8 U/mg protein). Additionally, the COS mixture obtained from wheat bran/commercial chitin showed a higher concentration of reducing sugars, reaching 87.85 mM, compared to shrimp waste chitin (14.87 mM). The COS profile from wheat bran/commercial chitin included monomers to heptamers, while the profile from shrimp waste chitin was predominantly composed of monomers. These results highlight the advantages of SSF for chitinase induction and COS production in T. harzianum, offering potential applications as dietary fiber, antioxidants, and antimicrobial agents. The findings contribute to by-product valorization, waste reduction, and the sustainable generation of valuable products through SSF-based enzyme production.

Chitinase Profile of Arabidopsis, Subjected to the Combined Stress of Soil Salinity, Cuscuta campestris Parasitism and Herbivores

Plants are continuously subjected to changing environmental factors, often growing in suboptimal conditions. Due to the negative impact on agricultural yield numerous researches are published every year, studying the stress response and adaptation in plants to stress factors. Most of the studies, however, are dedicated to a single stress factor. In the present study, we examined the effect of a different combination of stresses on the chitinase profile of Arabidopsis plants. First, soil salinity (abiotic stress) was applied by irrigation with 150 mM NaCl. The plants were either infected or not with the parasitic flowering plant Cuscuta campestris Yunck. (dodder) and further challenged with the herbivorous attack – the larvae of either the sciarid fly Lycoriella ingenua (Dufour, 1839) or the citrus flatid planthopper Metcalfa pruinosa (Say, 1830). It was found that salinity and Cuscuta parasitism suppressed the response of Arabidopsis to sciarid flies, simultaneously with induction of chitinases in terms of the number of isoforms and relative activity in the parasite itself. Meanwhile, in the presence of Cuscuta, M. pruinosa tend to feed predominantly on the parasitic plant, completely ignoring the host. This was accompanied by the appearance of new chitinases, also suppressed by salinity. These results suggest complicated, antagonistic interactions between abiotic and different biotic stresses. It was also shown that the parasite is sensing the herbivore attack indirectly (in the case of L. ingenua) and transferring the stress signal to the host (in the case of M. pruinosa).

Endophyte Chaetomium globosum improves the growth of maize plants and induces their resistance to late wilt disease

Late wilt is a soil-borne disease caused by Cephalosporium maydis that severely limits maize production. In this study, endophytic Chaetomium isolates were screened for their abilities to control C. maydis on agar plates. In a dual culture test, Chaetomium spp. isolate Ch-1 inhibited 91.0% mycelial growth of C. maydis. The pathogen’s mycelial growth and conidial germination were also inhibited by its crude extracts. This isolate was identified as C. globosum (Chg-1) based on sequencing of the internal transcribed spacer regions of the rRNA gene. There are three Chg-1 application methods viz. grain treatment GT, soil application SA either individually or in combination GT + SA and two maize cultivars viz. landraces and fine seed 1005 were applied in pots and field plot experiments in controlling late wilt disease. In pots, Chg-1 treatments significantly reduced late wilt disease incidence and increased plant growth of the two maize cultivars, with a high efficacy for GT + SA compared to the positive control. Despite minor differences, treatments GT and SA provided adequate protection against late wilt. After 90 days of cultivation, the endophyte Chg-1 was re-isolated from the internodes of treated maize plants without causing any symptoms. This endophytic fungus reduced late wilt incidence in pots not only directly by antagonizing the pathogen, but also indirectly by inducing resistance mechanisms in maize plants. The induction of antioxidant enzymes (including peroxidase and polyphenoloxidase), chitinase, chlorophyll content, total phenols, and flavonoids was responsible for the indirect effects of Chg-1 against the pathogen. In the field, the endophyte not only reduced late wilt symptoms but also increased ear yield on both maize cultivars when compared to the untreated control. A combination of soil application and grain treatment with Chg-1 (GT + SA) outperformed any of these treatments individually in terms of reducing late wilt incidence and increasing grain yield in maize.

Inhibition of CHIT1 as a novel therapeutic approach in idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a progressive and eventually fatal lung disease with a complex etiology. Approved drugs, nintedanib and pirfenidone, modify disease progression, but IPF remains incurable and there is an urgent need for new therapies. We identified chitotriosidase (CHIT1) as new driver of fibrosis in IPF and a novel therapeutic target. We demonstrate that CHIT1 activity and expression are significantly increased in serum (3-fold) and induced sputum (4-fold) from IPF patients. In the lungs CHIT1 is expressed in a distinct subpopulation of profibrotic, disease-specific macrophages, which are only present in patients with ILDs and CHIT1 is one of the defining markers of this fibrosis-associated gene cluster. To define CHIT1 role in fibrosis, we used the therapeutic protocol of the bleomycin-induced pulmonary fibrosis mouse model. We demonstrate that in the context of chitinase induction and the macrophage-specific expression of CHIT1, this model recapitulates lung fibrosis in ILDs. Genetic inactivation of Chit1 attenuated bleomycin-induced fibrosis (decreasing the Ashcroft scoring by 28%) and decreased expression of profibrotic factors in lung tissues. Pharmacological inhibition of chitinases by OATD-01 reduced fibrosis and soluble collagen concentration. OATD-01 exhibited anti-fibrotic activity comparable to pirfenidone resulting in the reduction of the Ashcroft score by 32% and 31%, respectively. These studies provide a preclinical proof-of-concept for the antifibrotic effects of OATD-01 and establish CHIT1 as a potential new therapeutic target for IPF.

Chitinase-Induced Airway Hyperreactivity and Inflammation in a Mouse Model of Nonallergic Asthma

Introduction: Environmental exposure to mites and fungi has been proposed to critically contribute to the development of IgE-mediated asthma. A common denominator of such organisms is chitin. Human chitinases have been reported to be upregulated by interleukin-13 secreted in the context of Th2-type immune responses and to induce asthma. We assessed whether chitin-containing components induced chitinases in an innate immune-dependent way and whether this results in bronchial hyperresponsiveness. Materials and Methods: Monocyte/macrophage cell lines were stimulated with chitin-containing or bacterial components in vitro. Chitinase activity in the supernatant and the expression of the chitotriosidase gene were measured by enzyme assay and quantitative PCR, respectively. Non-sensitized mice were stimulated with chitin-containing components intranasally, and a chitinase inhibitor was administered intraperitoneally. As markers for inflammation leukocytes were counted in the bronchoalveolar lavage (BAL) fluid, and airway hyperresponsiveness was assessed via methacholine challenge. Results: We found both whole chitin-containing dust mites as well as the fungal cell wall component zymosan A but not endotoxin-induced chitinase activity and chitotriosidase gene expression in vitro. The intranasal application of zymosan A into mice led to the induction of chitinase activity in the BAL fluid and to bronchial hyperresponsiveness, which could be reduced by applying the chitinase inhibitor allosamidin. Discussion: We propose that environmental exposure to mites and fungi leads to the induction of chitinase, which in turn favors the development of bronchial hyperreactivity in an IgE-independent manner.

Expression of the pathogenesis related proteins during sesame-Macrophomina phaseolina interaction

Sesamum indicum L. is highly vulnerable to biotic stresses in which charcoal rot disease cuased by Macrophomina phaseolina is one of the major constraints of sesame yield. In response to pathogen infection plant produces a large amount of secondary metabolites like PR proteins, phenolics and other signaling compounds. In present investigation the role PR proteins β-1,3 glucanases and chitinases during host-pathogen interaction was studied at different time interval i.e. 0, 24, 48 and 72 hours post inoculation. Maximum induction of β, 1-3 glucanases was found at 48hpi in resistant genotypes than the susceptible. However maximum chitinase induction was noted in susceptible genotypes at 48 hpi. The expression of both genes was studied by quantitative real time PCR which was also supported the biochemical enzyme assay.

ATP-Binding Cassette Transporter Regulates N,N'-diacetylchitobiose Transportation and Chitinase Production in Trichoderma asperellum T4.

ATP-binding cassette (ABC) transporters are a superfamily of proteins that transport nutrient substances and secondary metabolites through cell membranes. They also act as an uptake system for N,N′-diacetylchitobiose (GlcNAc)2 in Streptomyces coelicolor. (GlcNAc)2 is an important inducer of chitinase. However, whether the ABC transporter in Trichoderma spp. is also responsible for (GlcNAc)2 uptake and chitinase induction has not yet been confirmed. In this study, we applied RNA interference and overexpression technologies to alter the expression level of the ABC-B transporter in order to detect changes in its transportation ability and the expression level of inducible endo-chitinase ECH42—an important biocontrol enzyme in Trichoderma asperellum. The results revealed that, after interference with the expression of the ABC-B transporter, T. asperellum T4 was only able to grow normally when glucose was the only carbon source. Compared with the wild-type, the efficiency of (GlcNAc)2 by the overexpression strain evidently increased, along with the activity level of ECH42. In conclusion, one of the functions of the ABC-B transporter in T. asperellum is the uptake and transport of (GlcNAc)2 into cells, and chitobiose is a strong inducer of ECH42 in T. asperellum T4.

Induction of Chitinase and Brown Spot Disease Resistance by Oligochitosan and Nanosilica–Oligochitosan in Dragon Fruit Plants

The brown spot disease caused by Neoscytalidium dimidiatum fungus on dragon fruit plants (Hylocereus undatus) is an extremely serious disease. Oligochitosan (OC) and nanosilica (nSiO2) have been considered as effective plant elicitors. In this study, OC with Mw of 3000, 5000, and 7000 g/mol was prepared by γ-irradiation and nSiO2 with size ~ 45 nm was synthesized from rice husk. Mixture of nSiO2–OC was prepared by dispersing nSiO2 in OC solution. The resistant effect against brown spot disease on dragon fruit plants was assessed by measuring the induced chitinase enzyme activity and the disease severity after spraying OC, nSiO2–OC and inoculating fungus. The results showed that all OC enhanced chitinase induction and reduced disease severity compared with control, and the OC ~ 3000 g/mol exhibited the highest activity. The nSiO2–OC also exhibited similar effect as OC and nSiO2, but it was more effective than individual OC or nSiO2 from 120 h onward.

INDUCED TEMPORAL AND SPATIAL VARIATION IN HOST DEFENCE ENZYMES IN RESPONSE TO FUSARIUM WILT IN CHICKPEA

The present study evaluated the defense response of Chickpea wilt resistant and susceptible cultivars inoculated with pathogen Fusarium oxyporum f.sp. ciceri (Foc). Evaluation of pre-induced and pathogen-induced defense at 7 (S1), 15 (S2) and 30 (S3) days showed that the enzymatic activities differed not only within the root, stem and leaves but also between susceptible and resistant cultivars of chickpea and increased after inoculation with Foc. Peroxidase (PO) activity increased in all the tissues from S1 to S2 and declined thereafter. Conspicuous changes occurred at the rate of increase in activity of the enzyme between resistant and susceptible cultivars upon Foc inoculation over their corresponding control at the S2. Polyphenol oxidase (PPO) activity in resistant cultivars increased by 30% with over uninoculated control and induction was up to S3. The level of enzyme activity diminished from S2 to S3 and even fell below control levels in susceptible cultivars. Catalase (CAT) activity followed peroxidase trend however it was induced at S1 in Foc inoculated and at S2 in un-inoculated plants. Increase in CAT induction was significant in leaf tissues of infected plants and continued up to S3. Phenylalanine ammonia lyase (PAL) activity increased from S1 to S2 and thereafter it either slightly decreased or remained unchanged at S3. Foc inoculation elicited a sharp increase in PAL activity in the leaf and stem tissue of resistant cultivars. Foc inoculated induced β-1,3-glucanase and chitinase activity in the test cultivars. Maximum induction of chitinase was observed at S2 in roots of resistant cultivars whereas un-inoculated plants showed much less conspicuous changes. β-1,3-glucanase activity was high in stem tissues. Both control and challenged plants had higher levels of β-1,3-glucanase activity at S2 and S3, but the proportionate increase was much higher in resistant cultivars. The expression pattern of these defense enzymes reveals their use as established resistance markers and provides scope for manipulating their expression and development of wilt-resistant transgenic chickpea.

Chitinase Induction Prior to Caspofungin Treatment of Experimental Invasive Aspergillosis in Neutropenic Rats Does Not Enhance Survival.

Host chitinases, chitotriosidase and acidic mammalian chitinase (AMCase), improved the antifungal activity of caspofungin (CAS) against Aspergillus fumigatus in vitro These chitinases are not constitutively expressed in the lung. Here, we investigated whether chitosan derivatives were able to induce chitinase activity in the lungs of neutropenic rats and, if so, whether these chitinases were able to prolong survival of rats with invasive pulmonary aspergillosis (IPA) or of rats with IPA and treated with CAS. An oligosaccharide-lactate chitosan (OLC) derivative was instilled in the left lung of neutropenic rats to induce chitotriosidase and AMCase activities. Rats instilled with OLC or with phosphate-buffered saline (PBS) were subsequently infected with A. fumigatus and then treated with suboptimal doses of CAS. Survival, histopathology, and galactomannan indexes were determined. Instillation of OLC resulted in chitotriosidase and AMCase activities. However, instillation of OLC did not prolong rat survival when rats were subsequently challenged with A. fumigatus In 5 of 7 rats instilled with OLC, the fungal foci in the lungs were smaller than those in rats instilled with PBS. Instillation of OLC did not significantly enhance the survival of neutropenic rats challenged with A. fumigatus and treated with a suboptimal dosage of CAS. Chitotriosidase and AMCase activities can be induced with OLC, but the presence of active chitinases in the lung did not prevent the development of IPA or significantly enhance the therapeutic outcome of CAS treatment.

Analysis of variation in virulence of Beauveria bassiana against insect pests of pigeonpea using qPCR.

Beauveria bassiana is a broad spectrum microbial bioagent used for the control of agriculturally important insect pests. However, in our experiments, two virulent isolates of B. bassiana (B2 and B10) showed specific preference toward Maruca vitrata and Helicoverpa armigera of pigeonpea. To better understand this feature, we developed a qPCR assay to quantify the chitinase (virulence factor) of B. bassiana during the infection process. Isolates of B. bassiana were grown on insect cuticle amended medium and minimal medium (without insect cuticle) to assess the induction of chitinase. Our results revealed a positive correlation between expression of chitinase by B. bassiana and the substrates (with or without cuticles of M. vitrata and H. armigera) used. This study showcases the methodology to quantify the chitinase and analysis of variation in virulence of B. bassiana (B2 and B10) against M. vitrata and H. armigera.

Characterization and expression analysis of chitinase genes (CHIT1, CHIT2 and CHIT3) in turbot (Scophthalmus maximus L.) following bacterial challenge

Chitinases are hydrolytic enzymes which have been employed to breakdown chitin coats of pathogenic microorganisms, thereby weaken the defense system of several pathogens and insects. In this regard, we identified the chitinase genes of turbot and characterized their expression patterns in mucosal tissues following Vibrio anguillarum and Streptococcus iniae challenge. In present study, transcripts of three chitinase genes (CHIT1, CHIT2 and CHIT3) were captured, as well as their protein structures and expression patterns following different bacterial infection were also characterized. The chitinases were widely expressed in all tested tissues with the highest expression levels of CHIT1 and CHIT2 in intestine, and CHIT3 in skin. Finally, these three genes showed different expression patterns following bacterial challenge. The significant quick induction of chitinases in mucosal surfaces against infection indicated their key roles to prevent pathogen attachment and entry in mucosal immunity. Functional studies should further characterize the chitinases and avail utilization of their function to increase the disease resistance in maintaining the integrity of the mucosal barriers against infection and facilitating the disease resistant family/strain selection in turbot.

Modulation of the activity of chitinases and β-1,3 glucanase in seedlings of cucumber and chilli by the aqueous extract of Cleistanthus collinus

Present paper reports induction of chitinases and β-1,3 glucanase in cucumber and chilli by the aqueous extract of the aerial parts of Azadirachta indica and Cleistanthus collinus. Efficacy of these extracts to induce the activity of chitinases and β-1,3 glucanase was concentration dependent. Similarly, magnitude of the enzyme activities also depended on the crop species and seedling part. Besides induction of enzyme activity, the extract of C. collinus and its fraction eluted with 90% methanol over silica gel 60–120 column modulated the expression of chitinase and β-1,3 glucanase isoforms. Phytochemical characterization of the extract of C. collinus and its 90% methanol fraction revealed several bioactive secondary metabolites, which might be active in influencing the activity of chitinases and β-1,3 glucanase.

Induction and Expression of Chitinases from Four Sub Species of Bacillus thuringiensis

Induction and Expression of Chitinases from Four Sub Species of Bacillus thuringiensis

A global study of transcriptome dynamics in canola (Brassica napus L.) responsive to Sclerotinia sclerotiorum infection using RNA-Seq

The necrotrophic phytopathogen, Sclerotinia sclerotiorum, causes Sclerotinia stem rot, which is a serious constraint to canola (Brassica napus L.) production worldwide. To understand the detailed molecular mechanisms underlying host response to Sclerotinia infection, we analyzed the transcript level changes in canola post-infection with S. sclerotiorum in a time course of a compatible interaction using strand specific whole transcriptome sequencing. Following infection, 161 and 52 genes (P≤0.001) were induced while 24 and 23 genes were repressed at 24h post-inoculation (hpi) and 48hpi, respectively. This suggests that, a gradual increase in host cell lyses and increase virulence of the pathogen led to the expression of only a fewer host specific genes at the later stage of infection. We observed rapid induction of key pathogen responsive genes, including glucanases, chitinases, peroxidases and WRKY Transcription factors (TFs) within 24hpi, indicating early detection of the pathogen by the host. Only 16 genes were significantly induced at both the time points suggesting a coordinated suppression of host responses by the pathogen. In addition to genes involved in plant-pathogen interactions, many novel disease responsive genes, including various TF sand those associated with jasmonate (JA) and ethylene (ET) signalling were identified. This suggests that canola adopts multiple strategies in mediating plant responses to the pathogen attack. Quantitative real time PCR (qRT-PCR) validation of a selected set of genes demonstrated a similar trend as observed by RNA-Seq analysis and highlighted the potential involvement of these genes by the host to defend itself from pathogen attack. Overall, this work presents an in-depth analysis of the interaction between host susceptibility and pathogen virulence in the agriculturally important B. napus-S. sclerotiorum pathosystem.

Aeromonas chitinase degrades chironomid egg masses.

Chironomids are freshwater insects that undergo a complete metamorphosis of four life stages. Chironomid egg masses can be degraded by Vibrio cholerae and some Aeromonas species. Egg mass degradation by V. cholerae requires haemagglutinin protease activity. Our aim was to identify the egg mass degrading (EMD) factor secreted by Aeromonas dhkanesis 3K1C15. Following the hypothesis that the EMD factor of A. dhkanesis is also a protease, secreted proteases were screened, but none of them proved to have the same properties as the EMD factor. Using conventional protein purification methods, we found that the active fraction included chitinases. We further confirmed chitin as a building block of the egg masses. Interestingly, by supplementing bacterial growth media with chitin, we observed unexpected EMD factor activity in Aeromonas isolates that initially were not able to degrade egg masses. Accordingly, we concluded that although strain 3K1C15 secretes chitinases constitutively, most Aeromonas strains secrete chitinases inductively. Induction of chitinases in nature presumably occurs when bacteria are attached to the egg mass habitat, in which chitin is abundant. Considering that chitinases are highly conserved across bacteria phyla, we assume that the role of this enzyme in the bacteria-insect interplay could be wider than is currently thought.

English

Six Trichoderma strains (collected from IARI, New Delhi and MTCC, Chandigarh) were tested for their ability to inhibit soil-borne pathogen of groundnut mainly Sclerotium rolfsii (causing stem rot on groundnut). In vitro percent growth inhibition of S. rolfsii by various Trichoderma strains were recorded at 5th day after inoculation (DAI). Results obtained from the antagonism study indicated that Trichoderma viride (NBAII Tv 23) inhibited 61% growth of phytopathogenic fungi S. rolfsii followed by Trichoderma harzianum (NBAII Th1) (55% growth inhibition of pathogen). The specific activities of cell wall degrading enzymes chitinase, β-1,3 glucanase, protease and cellulase were tested during different incubation period (48, 72 and 96 h) when Trichoderma spp. grew in the presence of pathogen cell wall in synthetic media. The antagonist T. viride (NBAII Tv 23) induced higher chitinase and protease activity. The growth inhibition of pathogen during antagonism were positively correlated with coiling pattern of antagonists at 14th day after inoculation (DAI) as well as with the induction of chitinase, β-1,3 glucanase and total phenol content. However, the amount of cellulase and polygalacturonase recorded was least in these antagonists treatment. A significant positive correlation (p = 0.01) between percentage growth inhibition of test fungus and lytic enzymes (chitinase, β-1,3-glucanase and protease) in the culture medium of antagonist treatment established a relationship to inhibit growth of fungal pathogen by increasing the levels of these enzymes. Among all the tested Trichoderma strains, T. viride (NBAII Tv 23) was found to be the best strain to be used in biological control of plant pathogen S. rolfsii. Key words: Antagonism, soil-borne pathogens, lytic enzyme, Trichoderma, biocontrol agent.

English

Although Pythium myriotylum is a very destructive root pathogen of cocoyam, the host defense response in this plant-pathogen interaction has not been fully studied. Four cocoyam germplasm accessions were inoculated with P. myriotylum, and their induced defense responses were characterized. The induction and spatio-temporal accumulation of chitinase and b-1,3-glucanase were determined by enzymatic activity assays of crude root extracts from inoculated and non-inoculated (control) plants, sampled at 0, 2, 4, 6 and 8 days post inoculation (dpi). Furthermore, induced proteins were extracted from roots of inoculated and control tolerant (RO1054 and RO3015) and susceptible (RO2063) accessions at 8 dpi, and characterized by isoelectric focusing (IEF), sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and Western blot analyses. Chitinase and b-1,3-glucanase were consistently produced in high amounts in the roots of the tolerant accession RO1054, 8 days after inoculation. SDS-PAGE and immunoblotting showed that induced chitinases (37, 35 and 33 kDa) in the tolerant cocoyams were immunologically related to PR-3a purified from barley leaves inoculated with Erysiphe graminis f. sp. hordei, and induced osmotins (42-45 kDa) were immunologically related to osmotins purified from cultured NaCl-adapted tobacco protoplasts. These results suggest that tolerance in cocoyam infected with P. myriotylum may be associated in part with the production of pathogenesis-related (PR) proteins including one hydrolytic enzyme of known antifungal activity (PR-3). Key words: b-1,3-glucanase, chitinase, cocoyam, PR protein, Pythium myriotylum, osmotin.

Graphene oxide attenuates Th2-type immune responses, but augments airway remodeling and hyperresponsiveness in a murine model of asthma.

Several lines of evidence indicate that exposure to nanoparticles (NPs) is able to modify airway immune responses, thus facilitating the development of respiratory diseases. Graphene oxide (GO) is a promising carbonaceous nanomaterial with unique physicochemical properties, envisioned for a multitude of medical and industrial applications. In this paper, we determined how exposure to GO modulates the allergic pulmonary response. Using a murine model of ovalbumin (OVA)-induced asthma, we revealed that GO, given at the sensitization stage, augmented airway hyperresponsiveness and airway remodeling in the form of goblet cell hyperplasia and smooth muscle hypertrophy. At the same time, the levels of the cytokines IL-4, IL-5, and IL-13 were reduced in broncho-alveolar lavage (BAL) fluid in GO-exposed mice. Exposure to GO during sensitization with OVA decreased eosinophil accumulation and increased recruitment of macrophages in BAL fluid. In line with the cytokine profiles, sensitization with OVA in the presence of GO stimulated the production of OVA-specific IgG2a and down-regulated the levels of IgE and IgG1. Moreover, exposure to GO increased the macrophage production of the mammalian chitinases, CHI3L1 and AMCase, whose expression is associated with asthma. Finally, molecular modeling has suggested that GO may directly interact with chitinase, affecting AMCase activity, which has been directly proven in our studies. Thus, these data show that GO exposure attenuates Th2 immune response in a model of OVA-induced asthma, but leads to potentiation of airway remodeling and hyperresponsiveness, with the induction of mammalian chitinases.

The Characteristics of Chitinase Expression in Aeromonas schubertii

In this study, chitinase activity in an incubation broth of Aeromonas schubertii was measured using colloidal chitin azure as the substrate. More specifically, the induction of chitinases due to amendment with various carbon sources was examined. The highest chitinase activity was found following amendment with 0.5-1.0 % chitin powder, whereas the activity increased negligibly due to amendment with other carbon sources, such as glucose, GlcNAc, GlcN, sorbitol, sucrose, cellulose, or starch. The chitinase activity induced by the chitin powder was suppressed when the glucose, GlcNAc, GlcN, or starch was added simultaneously to the medium but was not suppressed by the addition of sorbitol, sucrose, or cellulose. The activity of chitinase in the crude extract was also not directly inhibited by glucose. Taken together, these findings suggest that the induction of chitinase activity depends on the acquisition of suitable carbon sources from the environment and that induction occurs at a regulatory level.