The monoterpene limonene in orange peels attracts pests and microorganisms

Plant volatiles include terpenoids, which are generally involved in plant defense, repelling pests and pathogens and attracting insects for herbivore control, pollination and seed dispersal. Orange fruits accumulate the monoterpene limonene at high levels in the oil glands of their fruit peels. When limonene production was downregulated in orange fruits by the transgenic expression of a limonene synthase (CitMTSE1) in the antisense configuration, these fruits were resistant to the fungus Penicillium digitatum (Pers.) Sacc. and the bacterium Xanthomonas citri subsp. citri and were less attractive to the medfly pest Ceratitis capitata. These responses were reversed when the antisense transgenic orange fruits were treated with limonene. To gain more insight into the role of the limonene concentration in fruit responses to pests and pathogens, we attempted to overexpress CitMTSE1 in the sense configuration in transgenic orange fruits. Only slight increases in the amount of limonene were found in sense transgenic fruits, maybe due to the detrimental effect that excessive limonene accumulation would have on plant development. Collectively, these results suggest that when limonene reaches peak levels as the fruit develops, it becomes a signal for pest and pathogen attraction, which facilitate access to the fruit for pulp consumers and seed dispersers.

Molecular cloning and characterisation of a pathogenesis-related protein CsPR10 from Crocus sativus

Plants have developed many mechanisms to protect themselves against most potential microbial pathogens and diseases. Among these mechanisms, pathogenesis-related proteins are produced as part of the active defence to prevent attack. In this study, a full-length cDNA encoding the CsPR10 protein was identified in fresh saffron stigmas (Crocus sativus). The deduced amino acid sequence from the nucleotide sequence of the coding region showed homology with PR10 proteins. The clone expressed as a protein in fusion with a GST tag produced a 47-kDa protein in E. coli. CsPR10 had ribonuclease activity, with features common to class II-type ribonucleases; its specific activity was quantified as 68.8 U·mg(-1) protein, thus falling within the range of most PR10 proteins exhibiting RNase activity. Antifungal activity of CsPR10 was assayed against Verticillium dahliae, Penicillium sp. and Fusarium oxysporum. CsPR10 inhibited only F. oxysporum growth, and antifungal potency was reflected in a IC(50) of 8.3 μm. Expression analysis showed the presence of high transcript levels in anther and tepal tissues, low levels in stigmas and roots, and no signal detected in leaves. This protein seems to be involved in the active defence response through activation of the jasmonic acid pathway.

Contrasting nephropathic responses to oral administration of extract of cultured Penicillium polonicum in rat and primate

Liquid- or solid substrate-cultured Penicillium polonicum administered in feed to rats over several days evokes a histopathological response in kidney involving apoptosis and abnormal mitosis in proximal tubules. The amphoteric toxin is yet only partly characterized, but can be isolated from cultured sporulating biomass in a fraction that is soluble in water and ethanol, and exchangeable on either anion- or cation-exchange resins. After several weeks of treatment renal proximal tubule distortion became striking on account of karyocytomegaly, but even treatment for nearly two years remained asymptomatic. Extract from a batch of solid substrate fermentation of P. polonicum on shredded wheat was incorporated into feed for rats during four consecutive days, and also given as an aqueous solution by oral gavage to a vervet monkey daily for 10 days. Treatment was asymptomatic for both types of animal. Rat response was evident as the typical renal apoptosis and karyomegaly. In contrast there was no such response in the primate; and neither creatinine clearance nor any haematological characteristic or serum component concentration deviated from a control or from historical data for this primate. The contrast is discussed concerning other negative findings for P. polonicum in pigs and hamsters. Renal karyomegaly, as a common rat response to persistent exposure to ochratoxin A, is not known in humans suspected as being exposed to more than the usual trace amounts of dietary ochratoxin A. Therefore the present findings question assumptions that human response to ochratoxin A conforms to that in the rat.

Response of jujube fruits to exogenous oxalic acid treatment based on proteomic analysis

In this study, we found that oxalic acid (OA) at the concentration of 5 mM could delay jujube fruit sene-scence by reducing ethylene production, repressing fruit reddening and reducing alcohol content, which consequently increased fruit resistance against blue mold caused by Penicillium expansum. In order to gain a further understanding of the mechanism by which OA delays senescence and increases disease resistance of jujube fruit, we used a proteomics approach to compare soluble proteome of jujube fruits treated with water or 5 mM OA for 10 min. A total of 25 differentially expressed proteins were identified by using electrospray ionization quadrupole time-of-flight tandem mass spectrometry (ESI-Q-TOF-MS/MS). Among these proteins, alcohol dehydrogenase 1, which plays a direct role in ethanol metabolism, was repressed, and the abundances of three photosynthesis-related proteins was enhanced in jujube fruit after OA treatment. The protein identified as a cystathionine beta-synthase domain-containing protein, which can regulate ethylene precursors, was also induced by OA treatment. The activity of 1-aminocyclopropane-1-carboxylic acid synthase was significantly suppressed in OA-treated jujube fruit. In addition, three proteins related to the defense/stress response were up-regulated by OA, and contributed to the establishment of systemic resistance induced by OA in jujube fruits. These results indicated that OA treatment might affect ethanol and ethylene metabolism, resulting in delaying senescence, and increase resistance of jujube fruits against fungal pathogens.

Abiotic stresses sequentially applied enhance natural resistance and reduce postharvest decay

The feasibility to restrain citrus green mould (Penicillium digitatum Sacc.) during storage, by means of induced natural resistance, was investigated following combined heat and ultravioLet light C (254 nm, UV-C) treatments. Heat treatment (HT) was performed by keeping Citrus fruits in a humid saturated room at 36 degrees C for 36 h while, the UV-C light treatment (254 nm) was carried out by illuminating the fruits with 3 or 6 kJm(-2). Physical treatments were sequential and reversely applied to un-inoculated or to 24 h-old inoculated lemons or oranges. Then, fruits were stored for 30 days at 8 or 5 degrees C with 95% relative humidity (RH) followed by a 6 day simulated marketing period at 20 degrees C and 75% RH. Constitutive (cuticle and epicuticular wax) and induced resistance (scoparone biosynthesis) were monitored and the variation in natural resistance was correlated to the decay development. HT influenced positively the constitutive factors of resistance by reducing or delaying cuticular cracking and by remodelling the epicuticular wax layer. Following HT the synthesis of scoparone took place only in the albedo of wounds and was greater when fruits were inoculated. Following UV-C illumination, scoparone accumulated rapidly in the outer rind (flavedo) but, particularly with 6 kJm(-2), favoured cuticular fracturing during storage. Sequential treatments resulted significantly more effective in controlling decay on either, inoculated and non inoculated fruit. The best control of green mould during storage of lemons and oranges was obtained when HT preceded 6 kJm(-2) UV-C illumination with 52 and 45% reduction of natural decay in fruit stored at 8 degrees C compared to the control, respectively.

Treatments with acetic acid followed by curing reduce postharvest decay on Citrus fruit

Citrus fruit are susceptible to many postharvest diseases and disorders, but Penicillium digitatum and Penicillium italicum are the most common and serious pathogens during storage and marketing. The continuous employ in packing houses of synthetic fungicides such as imazalil (IMZ) or thiabendazote for the control of these pathogens is promoting the selection of resistant biotypes. These considerations together with an increased attention for human health and the environment have multiplied the studies on new ecological technologies. In recent years researchers studies focused on alternatives to the chemical control of post-harvest decay, such as the utilization of GRAS compounds as well as physical methods. In the present study is reported the sequential use of acetic acid (AAC) followed by curing. The lemon variety "Verna" and the orange variety "Jaffa", naturally inoculated, were treated with vapours of AAC performed at three different concentration (15, 25 and 50 microL/L) for 15 minutes, after an incubation period of 24 hours at 27 degrees C and 90% relative humidity (RH). After treatments fruits were cured at 36 degrees C for 36 hours with 90% RH and subsequently stored at 8 degrees C and 90% of RH for eight weeks. Both citrus varieties were also treated with IMZ at a concentration of 200 mL/HL. At the end of the experiment decay and weight loss were evaluated. After 8 weeks of storage, in the lemon variety, the lowest percentage of infected wounds was 1.5% for both the fruit treated with IMZ or with AAC at 25 microL/L. Fruit treated with 15 mciroL/L or untreated (control) showed similar results with 13.6% and 16.6% of rotted fruit respectively. Different results were obtained with the orange variety, in this case the synthetic fungicide was the most effective at the end of the storage period, with 18.0% of decay. AAC treatments were not a successful as on lemons, the best result was achieved even in this case with AAC performed at 25 pL/L, but with 39.9% of decay. In both species the weight loss was not affected by the treatments. These results show that a good control of postharvest decay could be achieved, on lemon fruit, by combining the effect of a GRAS compound such as AAC with curing. Conversely the results obtained, by applying this control method to the orange variety were not so promising. Further researches are needed to shed light on the different behaviour between the two species.

Agrobacterium tumefaciens-mediated genetic transformation of the phytopathogenic fungus Penicillium digitatum

Agrobacterium tumefaciens-mediated transformation (ATMT) system was assessed for conducting insertional mutagenesis in Penicillium digitatum, a major fungal pathogen infecting post-harvest citrus fruits. A transformation efficiency of up to 60 transformants per 10(6) conidia was achieved by this system. The integration of the hph gene into the fungal genome was verified by polymerase chain reaction (PCR) amplification and sequencing. These transformants tested were also shown to be mitotically stable. Southern blot analysis of 14 randomly selected transformants showed that the hph gene was randomly integrated as single copy into the fungal genome of P. digitatum. Thus, we conclude that ATMT of P. digitatum could be used as an alternatively practical genetic tool for conducting insertional mutagenesis in P. digitatum to study functional genomics.

Cloning, characterization and differential expression of an hsp70 gene from the pathogenic dimorphic fungus, Penicillium marneffei

A gene encoding heat shock protein 70 (Hsp70) of Penicillium marneffei was isolated and characterized. The structure of P. marneffei hsp70 gene was similar to hsp70 genes of other organisms, with a unique sequence of 3-nt microexon flanked by two introns. Comparison of the deduced amino acid sequence revealed that the Hsp70 was grouped in the fungal cytosolic Hsp70s. Northern blot analysis demonstrated the upregulation of hsp70 expression during the mycelium to yeast phase transition. Upregulation was also observed during yeast or mycelial cells encountering heat shock condition at 39 degrees C. Experimental analysis showed that the expression of hsp70 is temperature dependent. Contradictory, a severe heat shock condition at 42 degrees C resulted in lowering the hsp70 transcript. Reverse transcription-polymerase chain reaction (RT-PCR) showed the accumulation of a large population of mature mRNA and small population of intron II-unspliced hsp70 mRNA in most cell types (conidia, mycelia and yeast). These results suggested that the Hsp70 may play an important role in environmental stress response and adaptation.

The copper, zinc superoxide dismutase gene of Penicillium marneffei: cloning, characterization, and differential expression during phase transition and macrophage infection

Superoxide dismutase (SOD) is an enzyme that converts superoxide radicals into hydrogen peroxide and oxygen molecules. SOD has been shown to contribute to the virulence of many human-pathogenic fungi through its ability to neutralize toxic levels of reactive oxygen species generated by the host. SOD has also been speculated to be important in the pathogenesis of fungal infections, but the role of this enzyme has not been rigorously investigated. In this report, we isolated and characterized the copper, zinc superoxide dismutase gene, designated sodA, from the important human pathogenic fungus, Penicillium marneffei. The putative SodA polypeptide consisted of 154 amino acids and exhibited a significant level of similarity to other fungal Cu, Zn SODs. Differential expression of the sodA gene in P. marneffei was demonstrated by semi-quantitative RT-PCR. Apparently, the sodA transcript accumulated in conidia, but expression was downregulated in the mycelia phase. In contrast, transcript expression was upregulated in the yeast phase as well as during macrophage infection. The significantly higher expression of the sodA transcript during macrophage infection suggests that this gene might play an important role in stress responses and in the adaptation of P. marneffei to the internal macrophage environment. The latter may serve as a putative virulence factor of this fungus allowing for survival in the host cell.

Effects of co-culture of amoebae with indoor microbes on their cytotoxic and proinflammatory potential

Free-living amoebae are ubiquitous environmental protozoa found in both natural and man-made environments, including moisture-damaged buildings. Furthermore, the interaction between amoebae and bacteria has been shown to enhance the virulence and pathogenicity of some bacteria. While the inhabitants of moisture damaged buildings are known to be at risk of suffering adverse health effects, the exact causative agents and mechanisms are still obscure. To examine the possible role of amoebae in the health effects associated with moisture damages, the effects of amoebae on the cytotoxicity and proinflammatory potential of nonpathogenic microbes common in moisture-damaged buildings were investigated. First, two bacterial and three fungal strains were cultured both individually and in coculture with Acanthamoeba polyphaga. Then, mouse RAW264.7 macrophages were exposed to the cocultures as well as the individually grown bacteria, fungi, and amoebae. Finally, cell viability and production of proinflammatory mediators, i.e., nitric oxide (NO), tumor necrosis factor alpha (TNF-alpha), and interleukin 6 (IL-6), were measured in macrophages after the exposure. The results revealed that cocultivation with amoebae increased the cytotoxicity of the bacterium Streptomyces californicus and the fungus Penicillium spinulosum. Moreover, the macrophages produced up to 10 times higher concentrations of NO after the exposure to these cocultures than after the exposure to individually grown microbes. Finally, the production of the cytokines was up to two orders of magnitude higher (IL-6) and up to four times higher (TNF-alpha) after exposure to the cocultures when compared to individually grown microbes. We conclude that amoebae are able to potentiate the cytotoxicity and proinflammatory properties of certain microbes associated with moisture damages.

Crucial role of antioxidant proteins and hydrolytic enzymes in pathogenicity of Penicillium expansum: analysis based on proteomics approach

Penicillium expansum, a widespread filamentous fungus, is a major causative agent of fruit decay and may lead to the production of mycotoxin that causes harmful effects on human health. In this study, we compared the cellular and extracellular proteomes of P. expansum in the absence and presence of borate, which affects the virulence of the fungal pathogen. The differentially expressed proteins were identified using ESI-Q-TOF-MS/MS. Several proteins related to stress response (glutathione S-transferase, catalase, and heat shock protein 60) and basic metabolism (glyceraldehyde-3-phosphate dehydrogenase, dihydroxy-acid dehydratase, and arginase) were identified in the cellular proteome. Catalase and glutathione S-transferase, the two antioxidant enzymes, exhibited reduced levels of expression upon exposure to borate. Because catalase and glutathione S-transferase are related to oxidative stress response, we further investigated the reactive oxygen species (ROS) levels and oxidative protein carbonylation (damaged proteins) in P. expansum. Higher amounts of ROS and carbonylated proteins were observed after borate treatment, indicating that catalase and glutathione S-transferase are important in scavenging ROS and protecting cellular proteins from oxidative damage. Additionally to find secretory proteins that contribute to the virulence, we studied the extracellular proteome of P. expansum under stress condition with reduced virulence. The expression of three protein spots were repressed in the presence of borate and identified as the same hydrolytic enzyme, polygalacturonase.

[Penicilliosis in Laos]

INTRODUCTION

Penicilliosis is caused by Penicillium marneffei, a dimorphic fungus endemic in southeast Asia and southern China. Since 1988, this deep mycosis has been one of the most frequent opportunistic infections in subjects with HIV infection in this region. We report the first observation of penicilliosis in Laos in a subject infected by HIV.

CASE

A Laotian women with HIV infection and under treatment for tuberculosis, was hospitalized with a cough, fever and cervical lymphadenopathy. A lymph node smear stained with RAL 555 confirmed the diagnosis of penicilliosis. The histologic examination detected some Penicillium marneffei, stained by PAS and Gomori-Grocot. The patient was treated successfully with ketoconazole.

DISCUSSION

Penicilliosis is endemic in southeast Asia. Especially in Thailand, it is a common opportunistic infection in HIV-infected persons. This case confirms the existence of penicilliosis in Laos, where its prevalence as an opportunistic infection is probably underestimated. The diagnostic method (slide stained with RAL 555) used in this case is simple, rapid, and appropriate for countries with limited economic resources to devote to the penicilliosis diagnosis.

Penicillium marneffei infection and recent advances in the epidemiology and molecular biology aspects

Penicillium marneffei infection is an important emerging public health problem, especially among patients infected with human immunodeficiency virus in the areas of endemicity in southeast Asia, India, and China. Within these regions, P. marneffei infection is regarded as an AIDS-defining illness, and the severity of the disease depends on the immunological status of the infected individual. Early diagnosis by serologic and molecular assay-based methods have been developed and are proving to be important in diagnosing infection. The occurrence of natural reservoirs and the molecular epidemiology of P. marneffei have been studied; however, the natural history and mode of transmission of the organism remain unclear. Soil exposure, especially during the rainy season, has been suggested to be a critical risk factor. Using a highly discriminatory molecular technique, multilocus microsatellite typing, to characterize this fungus, several isolates from bamboo rats and humans were shown to share identical multilocus genotypes. These data suggest either that transmission of P. marneffei may occur from rodents to humans or that rodents and humans are coinfected from common environmental sources. These putative natural cycles of P. marneffei infection need further investigation. Studies on the fungal genetics of P. marneffei have been focused on the characterization of genetic determinants that may play important roles in asexual development, mycelial-to-yeast phase transition, and the expression of antigenic determinants. Molecular studies have identified several genes involved in germination, hyphal development, conidiogenesis, and yeast cell polarity. A number of functionally important genes, such as the malate synthase- and catalase-peroxidase protein-encoding genes, have been identified as being upregulated in the yeast phase. Future investigations pertaining to the roles of these genes in host-fungus interactions may provide the key knowledge to understanding the pathogenicity of P. marneffei.

Effect of incubation temperature and relative humidity on lesion diameter of Botrytis cinerea Pers. and Penicillium expansum Link. on apple fruits

Previous studies carried out in our laboratory demonstrated that the growth of B. cinerea and P. expansum was highly influenced by water activity and temperature in 'in vitro' conditions. Regardless the temperature, a, minimal for growth was < or = 0.89 and equal to 0.89 for P. expansum and B. cinerea respectively. The effect of incubation temperature (5-25 degrees C) and relative humidity (RH 75-98%) on the lesion diameter of two common fungi B. cinerea and P. expansum was studied and modelled in the controlled laboratory conditions in order to validate previous findings. The obtained results showed that only temperature had a significant effect on fungal growth on wounded apples. The relative humidity of air had no direct influence on growth of fungi. The part of variation explained by both studied factors is 52 and 55% respectively for P. expansum and B. cinerea. 'Lack of Fit' test was no significant for models, suggesting a greater difference between observed and predicted values. The difference between observed and predicted values was 14 and 29% respectively for P. expansum and B. cinerea. Theses results is in contradiction as compared to in vitro conditions and underlined that the humidity inside wounded apple sites is highly sufficient to start the growth of both postharvest pathogens of apples.

Aureobasidium pullulansas a biocontrol agent of blue mold in "Rocha" pear

The blue mold of "Rocha" pear caused by Penicillium expansum is an important postharvest disease which is adequately controlled by application of synthetic fungicides. In recent years, strategies like biological control have been considered a desirable alternative to chemicals. Several studies have demonstrated the potential of the yeast-like fungus Aureobasidium pullulans for control of postharvest decay of pear. A Portuguese isolate of Aureobasidium pullulans was characterized and evaluated for its activity in reducing postharvest blue mold decay of "Rocha" pear caused by Penicillium expansum. Study of optimal conditions for antagonist growth was carried out in six different culture media. The effect of four maturity stages of fruits in the development of A. pullulans was also studied. Biocontrol studies were performed with two concentrations of the antagonist (3 x 10(8) and 4 x 10(9) CFU/ml). A. pullulans growth was significantly different (P < or = 0.001) according to the various media and time of incubation. Best results were obtained in Corn Meal Agar (CMA) and Potato Dextrose Agar (PDA) media which contains the higher concentration of glucose (20 mg/l). Medium resulted from fruits of the first harvest date presented lower colony diameter. Inoculation of A. pullulans at 3 x 10(8) and 4 x 10(9) CFU/ml reduced the incidence of the disease by 23 and 63%, and reduced the lesion diameter by 36 and 46%, respectively.

The protection of parsley seedlings (Petroselinum sativum Hoffm. ssp. microcarpum) against damping-off

The experiment was carried out in the years 2003 and 2004 on parsley cultivar: 'Berlinska', 'Cukrowa', 'Vistula' and 'Kinga'. Mycological analysis of parsley seeds showed, that the most common inhabitans were fungi from genus Alternaria (mainly A. alternata and A. radicina) and Fusarium, especially F. avenaceum and F. oxysporum. The two-year study on the effectiveness of 5 substances--biopreparate Biochikol 020 PC (polymer of chitosol) and Biosept 33 SL (extract of grape-fruit); and fungicides: Amistar 250 SC (BAS azoxystrobin), Dithane M-45 80WP (mancozeb) and Zaprawa Funaben T (carbendazim+thiram) used against parsley damping-off was conducted in glasshouse and field conditions. Seeds of parsley were treated one of tested substances before sowing. The results of glasshouse experiments showed, that the best efficacy exibited Amistar and Zaprawa Funaben T for seedlings cultivar 'Berlińska' and 'Cukrowa' and Biochikol for 'Kinga'. During field experiments Zaprawa Funaben T showed the best efficacy for seedlings 'Berlińska' and 'Vistula'. Preparate Amistar was the best seed dressing for parsley cultivar 'Cukrowa' and 'Kinga'. During glasshouse experiments in control the highest number of decaying seedlings had cultivar 'Berlinska', in field experiments 'Kinga'.

Effect of fluorescent pseudomonades and Trichoderma sp. and their combination with two chemicals on Penicillium digitatum caused agent of citrus green mold

Citrus green mold (Penicillium digitatum) causes economic losses. Chemical fungicides such as imazalil provide the primary means for controlling green mold decay of citrus fruits. Continuous use of fungicides has faced two major obstacles- increasing public concern regarding contamination of perishables with fungicidal residues, and proliferation of resistance in the pathogen populations. The aim of this research was to determine if the attacks of green mold on orange could be reduced by usage of biocontrol agent alone or in combination with low dosage of imazalil or sodium bicarbonate. Pseudomonas fluorescens isolate PN, P. fluorescens isolate PS and Trichoderma virens isolate TE were evaluated as potential biological agents for control of green mold of oranges caused by P. digitatum. Increasing concentration of SB decreased spore germination of P. digitatum. In laboratory tests, a cell suspension (10(8) cells per ml.) of bacterial strains reduced the incidence of green mold. On fruits surface biocontrol activity of antagonistic isolates was significantly increased when combined with low dosage of imazalil (500ppm) or sodium carbonate (5%). Effect of Trichoderma virens on controlling P. digitatum was better than others with or without these chemicals.

A case of hypersensitivity pneumonitis caused by Penicillium species in a home environment

We report a case of hypersensitivity pneumonitis in a 30-yr-old female housewife caused by Penicillium species found in her home environment. The patient was diagnosed according to history, chest radiograph, spirometry, high-resolution chest CT, and transbronchial lung biopsy. To identify the causative agent, cultured aeromolds were collected by the open-plate method. From the main fungi cultured, fungal antigens were prepared, and immunoblot analysis with the patient's serum and each fungal antigen was performed. A fungal colonies were isolated from the patient's home. Immunoblotting analysis with the patient's sera demonstrated a IgG-binding fractions to Penicillium species extract, while binding was not noted with control subject. This study indicates that the patient had hypersensitivity pneumonitis on exposure to Penicillium species in her home environment.

Effects of microbial cocultivation on inflammatory and cytotoxic potential of spores

Microbial growth on moisture-damaged building materials is commonly associated with adverse health effects in the occupants. In moisture damage situations, the environmental conditions as well as the dominant microbial species will vary, leading to a diversity of microbes and continual changes in the different microbial populations. Currently, very little is known about the effects of microbial cocultures on the potential harmfulness of the microbial population. In this study we have investigated the effects of cocultivation of certain indoor air microbes on the inflammatory and cytotoxic potential of their spores. We grew various microbial combinations made from strains of Streptomyces californicus, Stachybotrys chartarum, Aspergillus versicolor, and Penicillium spinulosum on wetted plasterboard. After 5 or 10 wk of growth, the spores were collected from the plasterboards, mouse RAW264.7 macrophages were exposed to the spores, and after 24 h the induced inflammatory and cytotoxic responses were analyzed. Among all the tested microbes and their combinations, the spores of Str. californicus proved to be the most potent inducer of cytotoxicity and inflammatory responses. These results indicate also that microbial coculture may support the growth of certain microbes with high immunotoxic potency such as Str.californicus. Furthermore, coculture containing S. chartarum and A. versicolor caused a synergistic increase in cytotoxicity compared to the sum response induced by the pure cultures, but no effect on inflammatory responses was detected. Generally, spore-induced cytotoxicity and production of inflammatory markers increased during the growth period from 5 to 10 wk, suggesting that the immunotoxic potency of spores increases with time.