Antifungal proteins from plants. Purification, molecular cloning, and antifungal properties of chitinases from maize seed. (41/261)

We have purified two 28-kDa chitinases, designated Chitinase A (Chit A) and Chitinase B (Chit B), from maize seeds to homogeneity and isolated cDNA clones encoding these two enzymes using an oligonucleotide probe based on an amino acid sequence of a peptide derived from Chit A. Although these two enzymes share 87% homology in their amino acid sequences, which were deduced from the nucleotide sequences of the isolated cDNA clones, they are significantly different in their biochemical and in vitro antifungal activities. When tested in vitro for antifungal activity against the growth of Trichoderma reesei, Alternaria solani, and Fusarium oxysporum, Chit A showed greater antifungal activity than Chit B. The specific activity of Chit A was determined to be 3-fold higher than that of Chit B. Chit A also had a 10-fold lower binding constant (Kd) against the substrate analogue N,N',N'',N'''-tetraacetyl chitotetrose than Chit B, indicating that the two enzyme may differ in their affinities for binding to the substrate chitin. Comparison of the amino acid sequences of maize seed chitinases with those of previously published chitinases from monocot and dicot plants indicates that maize seed chitinases have diverged significantly from other chitinases.  (+info)

Utility of molecular identification in opportunistic mycotic infections: a case of cutaneous Alternaria infectoria infection in a cardiac transplant recipient. (42/261)

We report on a case of cutaneous infection caused by Alternaria infectoria in a cardiac transplant recipient. A rapid molecular diagnosis was obtained by sequence analysis of the internal transcribed spacer domain of the 5.8S ribosomal DNA region amplified from colonies developed on Sabouraud medium. Treatment consisted of a combination of systemic antifungal therapy, first with amphotericin B and then with itraconazole.  (+info)

Atmospheric concentrations of Cladosporium spp. and Alternaria spp. spores in Zagreb (Croatia) and effects of some meteorological factors. (43/261)

The aim of the study was to analyse the relationship between meteorological conditions and Alternaria and Cladosporium spore concentrations in the air of Zagreb in August 2002 and August 2003. These months were chosen because they represented climatic extremes. A 7-day VPPS 2000 Hirst volumetric pollen and spore trap was used for spore sampling. Spores marked as 'others' (ascospores, basidiospores, Epicoccum, Ustilago, Pithomyces, Helminthosporium, Stemphylium, Torula, Botrytis, Didymella) were found to have predominated in the month of August in both 2002 and 2003 with 91.1% and 70.5%, respectively. Because of favourable weather conditions (higher air temperature and minimal precipitation) in August 2003, the concentrations of Alternaria and Cladosporium spores were 3.4-fold those recorded in the same month in 2002. Also, the peak daily concentrations of these spores were measured on days without precipitation and with higher air temperature. Intradiuranal variation in the Alternaria and Cladosporium spore concentrations was identical in 2002 and 2003 (lowest in 2-hour interval between 06:00-08:00, and highest between 10:00-12:00). In spite of the three-fold increase in the Cladosporium spore concentration in August 2003, the borderline concentration of 3,000 spores/m3 air that is associated with the occurrence of allergic reactions was only exceeded on a single day. Air concentration of Alternaria spores exceeded borderline value of 100 spores/m3 air on as many as 17 days, suggesting that at that time of the year the risk of allergic reaction was only present in individuals allergic to this spore type.  (+info)

Monitoring of Alternaria Ness and Cladosporium Link airborne spores in Lublin (Poland) in 2002. (44/261)

The concentration of Alternaria and Cladosporium spores was monitored throughout the year 2002 in Lublin (Eastern Poland). Fungal spores were sampled with Lanzoni VPPS 2000 volumetric spore trap. The total annual spore concentrations of Alternaria and Cladosporium reached 30,880 and 865,254 spores/m3, respectively. The majority of Alternaria spores was collected between 17:00-20:00, whereas Cladosporium spores were caught between 9:00-10:00.  (+info)

A new mouse model of lung allergy induced by the spores of Alternaria alternata and Cladosporium herbarum molds. (45/261)

Asthma is a serious health problem and during the last decade various experimental models of asthma have been developed to study the pathogenesis of this disease. In this study we describe a new mouse model of asthma that uses the spores of Alternaria alternata and Cladosporium herbarum, two allergenic molds recognized as common inducers of rhinitis and asthma in humans. Here we demonstrate that A. alternata and C. herbarum spores are immunogenic when injected into BALB/c mice, and induce the production of specific IgM and IgG1 antibodies and strongly increase IgE serum levels. To induce the allergic response, mice were sensitized by two intraperitoneal (i.p.) injections and then intranasaly (i.n.) challenged with A. alternata and C. herbarum spores. Bronchoalveolar lavages (BALs) from these mice contained numerous macrophages, neutrophils, eosinophils and lymphocytes whereas neutrophils were the predominant BAL inflammatory cells in nonsensitized mice. Histological studies demonstrated an influx of eosinophils in peri-vascular and peri-bronchial areas and the presence of numerous epithelial goblet cells only in sensitized mice. Increased expression of mRNA specific for various chemokines (eotaxin, MIP-1alpha, MIP-2) and chemokine receptors (CCR-1, CCR-2 and CCR-5) was observed in the lungs of nonsensitized mice challenged with the spores. Expression of CCR-3 mRNA in the lungs and Th2 cytokine (IL-4, IL-5 and IL-13) secretion in the BAL was additionally observed in sensitized and challenged mice. Finally we demonstrate through whole-body plethysmography that mold spore sensitization and challenge induce the development of an airway hyperreactivity in response to nebulized methacholine.  (+info)

Inhibition of polyketide synthesis in Alternaria alternata by the fatty acid synthesis inhibitor cerulenin. (46/261)

The fatty acid synthase inhibitor cerulenin (50 to 100 micrograms/ml) inhibited production of the polyketide mycotoxins alternariol (AOH) and alternariol monomethyl ether (AME) by the mold Alternaria alternata. The results suggested that AOH synthesis was inhibited by a direct mechanism by cerulenin, whereas production of AME was probably limited by a shortage of the precursor AOH.  (+info)

IP3 production in the hypersensitive response of lemon seedlings against Alternaria alternata involves active protein tyrosine kinases but not a G-protein. (47/261)

IP3 increase and de novo synthesis of scoparone are produced in the hypersensitive response (HR) of lemon seedlings against the fungus Alternaria alternata. To elucidate whether a G-protein and/or a protein tyrosine kinase (PTK) are involved in signal transduction leading to the production of such a defensive response, we studied the HR in this plant system after treatment with G-protein activators alone and PTK inhibitors in the presence of fungal conidia. No changes in the level of IP3 were detected in response to the treatment with the G-protein activators cholera toxin or mastoparan, although the HR was observed in response to these compounds as determined by the scoparone synthesis. On the contrary, the PTK inhibitors lavendustin A and 2,5-dihidroxy methyl cinnamate (DHMC) not only prevented the IP3 changes observed in response to the fungal inoculation of lemon seedlings but also blocked the development of the HR. These results suggest that the IP3 changes observed in response to A. alternata require a PTK activity and are the result of a G-protein independent Phospholipase C activity, even though the activation of a G-protein can also lead to the development of a HR. Therefore, it appears that more than one signaling pathway may be activated for the development of HR in lemon seedlings: one involving a G-protein and the other involving a PTK-dependent PLC.  (+info)

Secretome analysis reveals an Arabidopsis lipase involved in defense against Alternaria brassicicola. (48/261)

The Arabidopsis thaliana secretome was analyzed by the proteomic approach, which led to the identification of secreted proteins implicated in many aspects of cell biology. We then investigated the change in the Arabidopsis secretome in response to salicylic acid and identified several proteins involved in pathogen response. One of these, a secreted lipase with a GDSL-like motif designated GDSL LIPASE1 (GLIP1), was further characterized for its function in disease resistance. glip1 plants were markedly more susceptible to infection by the necrotrophic fungus Alternaria brassicicola compared with the parental wild-type plants. The recombinant GLIP1 protein possessed lipase and antimicrobial activities that directly disrupt fungal spore integrity. Furthermore, GLIP1 appeared to trigger systemic resistance signaling in plants when challenged with A. brassicicola, because pretreatment of the glip1 mutant with recombinant GLIP1 protein inhibited A. brassicicola-induced cell death in both peripheral and distal leaves. Moreover, glip1 showed altered expression of defense- and ethylene-related genes. GLIP1 transcription was increased by ethephon, the ethylene releaser, but not by salicylic acid or jasmonic acid. These results suggest that GLIP1, in association with ethylene signaling, may be a critical component in plant resistance to A. brassicicola.  (+info)