Daphnia magna model for the study of mycotoxins present in food: Gliotoxin, ochratoxin A and its combination

Mycotoxins are low molecular weight compounds present in food and feed. Although their effects on human health have been widely described, their mechanisms of action are still undefined. Gliotoxin (GTX) and ochratoxin A (OTA) are among the most dangerous mycotoxins produced by Aspergillus spp. Therefore, their toxicity was studied in the Daphnia magna model, which has high capacity to predict cytotoxicity and assess ecotoxicity, comparable to mammalian models. The study consisted of a series of tests to evaluate the effects of mycotoxins GTX, OTA and their combinations at different dilutions on Daphnia magna that were conducted according to standardized OECD 202 and 211 guidelines. The following assays were carried out: acute toxicity test, heartbeat, delayed toxicity test, reproduction, growth rate test. Reproducibility was determined by observing the offspring after 21 days of GTX exposure. In acute and delayed toxicity transcript levels of genes involved in xenobiotic metabolism (mox, gst, abcb1, and abcc5), and oxidative stress (vtg-SOD) were analyzed by qPCR. GTX showed acute toxicity and decreased heart rate in D. magna compared to OTA. On the other hand, OTA showed a delayed effect as evidenced by the immobility test. Both mycotoxins showed to increase genes involved in xenobiotic metabolism, while only the mycotoxin mixture increased oxidative stress. These results suggest that the mycotoxins tested could have negative impact on the environment and human health.

Involvement of pro-inflammatory mediators and cell cycle disruption in neuronal cells induced by gliotoxin and ochratoxin A after individual and combined exposure

Mycotoxins such as gliotoxin (GTX) and ochratoxin A (OTA) are secondary metabolites of Aspergillus and Penicillum found in food and feed. Both mycotoxins have shown to exert a detrimental effect on neuronal activity. The following study was carried out to elucidate the mechanisms by which GTX and OTA exert their toxicity. Non-differentiated SH-SY5Y neuronal-like cells were treated with GTX, OTA and their combinations to assess their cytotoxic effect using the MTT assay during 24, 48 and 72 h of exposure. Based on the results of the cytotoxic assays, cell cycle proliferation and immunological mediators were measured by determining the production of IL-6 and TNF-α using flow cytometry and ELISA, respectively. The IC50 values obtained were 1.24 and 1.35 µM when SH-SY5Y cells were treated with GTX at 48 h and 72 h, respectively. IC50 values of 8.25, 5.49 and 4.5 µM were obtained for OTA treatment at 24 h, 48 h and 72 h, respectively. The SubG0 phase increased in both treatments at 24 and 48 h. On the other hand, IL-6 and TNF-α production was increased in all mycotoxin treatments studied and was more pronounced for [GTX + OTA] after 48 h exposure. The additive and synergistic effect observed by the isobologram analysis between GTX and OTA resulted to a higher cytotoxicity which can be explained by the increased production of IL-6 and TNF-α inflammatory mediators that play an important role in the toxicity mechanism of these mycotoxins.

The antidepressant-like and glioprotective effects of the Y2 receptor antagonist SF-11 in the astroglial degeneration model of depression in rats: Involvement of glutamatergic inhibition

In this study, we explored the potential antidepressant-like properties of the brain-penetrant Y2 receptor (Y2R) antagonist SF-11 [N-(4-ethoxyphenyl)- 4-(hydroxydiphenylmethyl)- 1-piperidinecarbothioamide] in the astroglial degeneration model of depression with an emphasis on checking the possible mechanisms implicated in this antidepressant-like effect. The model of depression relies on the loss of astrocytes in the medial prefrontal cortex (mPFC) in Sprague-Dawley rats after administering the gliotoxin L-alpha-aminoadipic acid (L-AAA). SF-11 was administered intraperitoneally (i.p.) once (10 mg/kg) or for three consecutive days (10 mg/kg/day), and the effects of L-AAA and SF-11 injected alone or in combination were investigated using the forced swim test (FST), sucrose intake test (SIT), Western blotting, immunohistochemical staining, and microdialysis. SF-11 produced an antidepressant-like effect after single or three-day administration in rats subjected to astrocyte impairment, as demonstrated by the FST and SIT, respectively. Immunoblotting and immunohistochemical analyses showed that SF-11 reversed the L-AAA-induced astrocyte cell death in the mPFC, suggesting it is glioprotective. Microdialysis studies showed that SF-11 decreased extracellular glutamate (Glu) levels compared to basal value when administered alone and compared to the basal value and control group in LAAA-treated rats. The results from immunoblotting analysis indicated the involvement of Y2Rs in the astrocyte ablation model of depression and the antidepressant-like effect of SF-11. In addition, we observed the participation of the caspase-3 apoptotic pathway in the mechanism of gliotoxin action induced by L-AAA. These findings demonstrate that SF-11, a Y2R antagonist, elicited a rapid antidepressant-like response, possibly linked to its ability to inhibit glutamatergic neurotransmission.

Honey analysis in terms of nicotine, patulin and other mycotoxins contamination by UHPLC-ESI-MS/MS - method development and validation

Fifty-seven samples of honey of different types and origins were screened for nicotine and nine mycotoxins (aflatoxin B1, aflatoxin B2, fusarenon X, ochratoxin A, penicillic acid, zearalenone, sterigmatocystin, gliotoxin, and patulin). The sample set consisted of monofloral, multifloral, nectar, honeydrew, cream, and artificial honey originating mainly from Poland. The physicochemical characterization of honey was performed by determining colour (by Pfund method), water content (by refractometry), total phenolics and flavonoids content (by spectrophotometry). For nicotine and mycotoxins determination a QuEChERS-based UHPLC-ESI-MS/MS method was developed and validated. Analyses were carried out in alkaline conditions to ensure patulin-methanol adduct formation and facilitate this mycotoxin detection. About 33% of tested honey samples were contaminated by nicotine or/and mycotoxins. However, the presence of mycotoxins was not related to herein evaluated physicochemical parameters of honey samples.

Gliotoxin, a natural product with ferroptosis inducing properties

As one of the mycotoxins produced by Aspergillus fumigatus, gliotoxin has a variety of pharmacological effects, such as anti-tumor, antibacterial, immunosuppressive. Antitumor drugs induce tumor cell death in several forms, including apoptosis, autophagy, necrosis and ferroptosis. Ferroptosis is a recently identified unique form of programmed cell death characterized by iron-dependent accumulation of lethal lipid peroxides, which induces cell death. A large amount of preclinical evidence suggests that ferroptosis inducers may enhance the sensitivity of chemotherapy and the induction of ferroptosis may be an effective therapeutic strategy to prevent acquired drug resistance. In our study, gliotoxin was characterized as a ferroptosis inducer and showed strong anti-tumor activity with IC₅₀ of 0.24 μM and 0.45 μM in H1975 and MCF-7 cells at 72 h, respectively. Gliotoxin may provide a new natural template for the designing of ferroptosis inducers.

Gliotoxin Induced Ferroptosis by Downregulating SUV39H1 Expression in Esophageal Cancer Cells

BACKGROUND

Gliotoxin, a secondary metabolite isolated from marine-derived Aspergillus fumigatus, has demonstrated anti-tumor properties in several cancers. Ferroptosis, a recently discovered type of programmed cell death that depends on the accumulation of iron and lipid peroxides, participates in the occurrence and development of various diseases, including cancer. A recent patent, US20200383943, has suggested that the promotion of ferroptosis is a method of cancer treatment. Therefore, the development of drugs that induce ferroptosis in cancer cells would constitute a novel therapeutic approach.

OBJECTIVE

Gliotoxin is a natural compound which has exhibited anti-tumor properties in multiple cancers, however, studies of the effect of gliotoxin on esophageal cancer are lacking. Although cancer treatment has shown great progress, including traditional surgery, chemotherapy, radiotherapy, and immunotherapy, the prognosis of esophageal cancer is still poor. Therefore, the development of new treatment approaches for esophageal cancer is necessary.

METHODS

The effects of gliotoxin on esophageal cancer cells were determined by functional assays, such as CCK-8, wound healing and transwell assays. We used online tools to predict the target genes of gliotoxin, followed by further verification using Western blotting assays. To assess the role of gliotxin in inducing ferroptosis in esophageal cancer, we detected characteristics associated with ferroptosis including ROS, MDA, GSH and Fe²⁺.

RESULTS

Using online tools SEA and SwissTargetPrediction, we predicted that SUV39H1 was the gliotoxin target gene. Furthermore, in esophageal cancer tissues, SUV39H1 was expressed at higher levels than in normal tissues, while in patients with Esophageal Squamous Cell Carcinoma (ESCC), high expression levels of SUV39H1 indicated a poor prognosis. In vitro, we observed that gliotoxin increased ESCC cell death and inhibited cell migration. We treated ESCC cells with pan-caspase inhibitor Z-VAD-FMK or ferroptosis inhibitors, including Fer-1 and DFO. Our results showed that Fer-1 and DFO reduced the toxic effects of gliotoxin, while Z-VAD-FMK did not. Furthermore, gliotoxin treatment reduced tumor weight and volume in the xenograft tumor mouse model.

CONCLUSION

In summary, our findings indicate that gliotoxin downregulated SUV39H1 expression in ESCC cells and induced ferroptosis, suggesting a novel natural therapy for ESSC.

Identification of Gliotoxin isolated from marine fungus as a new pyruvate kinase M2 inhibitor

Pyruvate kinase M2 (PKM2) functions as an important rate-limiting enzyme of aerobic glycolysis that is involved in tumor initiation and progression. However, there are few studies on effective PKM2 inhibitors. Gliotoxin is a marine-derived fungal secondary metabolite with multiple biological activities, including immunosuppression, cytotoxicity, and et al. In this study, we found that Gliotoxin directly bound to PKM2 and inhibited its glycolytic activity in a dose-dependent manner accompanied by the decreases in glucose consumption and lactate production in the human glioma cell line U87. Moreover, Gliotoxin suppressed tyrosine kinase activity of PKM2, leading to a dramatic reduction in Stat3 phosphorylation in U87 cells. Furthermore, Gliotoxin suppressed cell viability in U87 cells, and cytotoxicity of Gliotoxin on U87 cells was obviously augmented under hypoxia condition compared to normal condition. Finally, Gliotoxin was demonstrated to induce cell apoptosis of U87 cells and synergize with temozolomide. Our findings identify Gliotoxin as a new PKM2 inhibitor with anti-tumor activity, which lays the foundation for the development of Gliotoxin as a promising anti-tumor drug in the future.

Hepatic Stellate Cells Play a Functional Role in Exacerbating Ischemia-Reperfusion Injury in Rat Liver

PURPOSE

The involvement of hepatic stellate cells (HSCs) with ischemia-reperfusion (I/R) injury in rat liver was examined using gliotoxin, which is known to induce HSC apoptosis.

METHODS

Male Sprague-Dawley rats were used. HSC was represented by a glial fibrillary acidic protein (GFAP)-positive cell. Liver ischemia was produced by cross-clamping the hepatoduodenal ligament. The degree of I/R injury was evaluated by a release of aminotransferases. Sinusoidal diameter and sinusoidal perfusion rates were examined using intravital fluorescence microscopy.

RESULTS

Gliotoxin significantly decreased the number of GFAP-positive cells 48 h after dosing (2.50 ± 0.19% [mean ± SD] in the nontreated group vs. 1.91 ± 0.46% in the gliotoxin-treated group). Liver damage was significantly suppressed by the pretreatment with gliotoxin. Sinusoidal diameters in zone 3 were wider in the gliotoxin group (10.25 ± 0.35 µm) than in the nontreated group (8.21 ± 0.50 µm). The sinusoidal perfusion rate was maintained as well in the gliotoxin group as in normal livers, even after I/R.

CONCLUSIONS

Pretreatment with gliotoxin significantly reduced the number of HSCs in the liver and further suppressed liver injury following I/R. It is strongly suggested that HSCs play a functional role in exacerbating the degree of I/R injury of the liver.

Preparations for Invasion: Modulation of Host Lung Immunity During Pulmonary Aspergillosis by Gliotoxin and Other Fungal Secondary Metabolites

Pulmonary aspergillosis is a severe infectious disease caused by some members of the Aspergillus genus, that affects immunocompetent as well as immunocompromised patients. Among the different disease forms, Invasive Aspergillosis is the one causing the highest mortality, mainly, although not exclusively, affecting neutropenic patients. This genus is very well known by humans, since different sectors like pharmaceutical or food industry have taken advantage of the biological activity of some molecules synthetized by the fungus, known as secondary metabolites, including statins, antibiotics, fermentative compounds or colorants among others. However, during infection, in response to a hostile host environment, the fungal secondary metabolism is activated, producing different virulence factors to increase its survival chances. Some of these factors also contribute to fungal dissemination and invasion of adjacent and distant organs. Among the different secondary metabolites produced by Aspergillus spp. Gliotoxin (GT) is the best known and better characterized virulence factor. It is able to generate reactive oxygen species (ROS) due to the disulfide bridge present in its structure. It also presents immunosuppressive activity related with its ability to kill mammalian cells and/or inactivate critical immune signaling pathways like NFkB. In this comprehensive review, we will briefly give an overview of the lung immune response against Aspergillus as a preface to analyse the effect of different secondary metabolites on the host immune response, with a special attention to GT. We will discuss the results reported in the literature on the context of the animal models employed to analyse the role of GT as virulence factor, which is expected to greatly depend on the immune status of the host: why should you hide when nobody is seeking for you? Finally, GT immunosuppressive activity will be related with different human diseases predisposing to invasive aspergillosis in order to have a global view on the potential of GT to be used as a target to treat IA.

Gliotoxin penetrates and impairs the integrity of the human blood-brain barrier in vitro

Cerebral fungal infections represent an important public health concern, where a key element of pathophysiology is the ability of the fungi to cross the blood-brain barrier (BBB). Yet the mechanism used by micro-organisms to cross such a barrier and invade the brain parenchyma remains unclear. This study investigated the effects of gliotoxin (GTX), a mycotoxin secreted by Aspergillus fumigatus, on the BBB using brain microvascular endothelial cells (BMECs) derived from induced pluripotent stem cells (iPSCs). We observed that both acute (2 h) and prolonged (24 h) exposure to GTX at the level of 1 μM or higher compromised BMECs monolayer integrity. Notably, acute exposure was sufficient to disrupt the barrier function in iPSC-derived BMECs, resulting in decreased transendothelial electrical resistance (TEER) and increased fluorescein permeability. Further, our data suggest that such disruption occurred without affecting tight junction complexes, via alteration of cell-matrix interactions, alterations in F-actin distribution, through a protein kinase C-independent signaling. In addition to its effect on the barrier function, we have observed a low permeability of GTX across the BBB. This fact can be partially explained by possible interactions of GTX with membrane proteins. Taken together, this study suggests that GTX may contribute in cerebral invasion processes of Aspergillus fumigatus by altering the blood-brain barrier integrity without disrupting tight junction complexes.

Gliotoxin destructs the pulmonary epithelium barrier function by reducing cofilin oligomer formation to promote the dissolution of actin stress fibers

The destruction of pulmonary epithelium is a major feature of lung diseases caused by the fungal pathogen Aspergillus fumigatus (A. fumigatus). Gliotoxin, a major mycotoxin of A. fumigatus, is widely postulated to be associated with the tissue invasion. However, the mechanism is unclear. In this study, we first discovered that cofilin, a regulator of actin dynamics in the pulmonary epithelial cells, existed mainly in the form of oligomer, which kept it unable to depolymerize actin filaments. Gliotoxin could reduce the formation of cofilin oligomer and promote the release of active cofilin monomer by regulating cofilin phosphorylation balance. Then, the active cofilin induced the dissolution of actin stress fibers to result in the disruption of pulmonary epithelium barrier function. Collectively, our study revealed a novel mechanism of gliotoxin destructing lung epithelium barrier function and for the first time indicated the role of cofilin oligomer in this process.

Chitosan stabilized gold nanoparticle mediated self-assembled gliP nanobiosensor for diagnosis of Invasive Aspergillosis

Diagnosis of Invasive Aspergillosis (IA) casused by Aspergillus fumigatus in miniaturized setting is challenging with great importance in human health. In this direction, we have designed a sensitive electrochemical nanobiosensor for diagnosis of IA through detecting the virulent glip target gene (glip-T) in a miniaturized experimetal setting. The sensor probe was fabricated using 1,6-Hexanedithiol and chitosan stabilized gold nanoparticle mediated self-assembly of glip probes (glip-P) on gold electrode. It was characterized by UV-visible spectroscopy, cyclic voltametry and electrochemical impedance spectroscopy. The ability of sensor to detect glip-T was analysed based on the hybridyzation reaction and the signal obtained using toluidine blue as indicator molecule. Analytical parameters were optimized in terms of glip-P concentration, temperature, reaction time, and concentration of toluidine blue. The biosensor showed the dynamic range between 1 × 10^-14- 1 × 10^-2 M with the detection limit of 0.32 ± 0.01 × 10^-14(RSD < 5.2%). The regeneration of biosensor was evaluated and the interference due to non-target oligonucleotide sequences was evaluated individualy as well as in mixed sample to validate the high selectivity of the designed sensor. The stability of the designed sensor was examined and practical applicability of biosensor was tested by detecting glip-T in real sample environment.

Antidepressant-like activity of the neuropeptide Y Y5 receptor antagonist Lu AA33810: behavioral, molecular, and immunohistochemical evidence

RATIONALE

It has recently been found that chronic treatment with the highly selective, brain-penetrating Y5 receptor antagonist, Lu AA33810 [N-[[trans-4-[(4,5-dihydro [1] benzothiepino[5,4-d] thiazol-2-yl) amino] cyclohexyl]methyl]-methanesulfonamide], produces antidepressant-like effects in the rat chronic mild stress model.

OBJECTIVE

In the present study, we investigated the possible antidepressant-like activity of Lu AA33810 in rats subjected to glial ablation in the prefrontal cortex (PFC) by the gliotoxin L-AAA, which is an astroglial degeneration model of depression.

RESULTS

We observed that Lu AA33810 administered intraperitoneally at a single dose of 10 mg/kg both reversed depressive-like behavioral changes in the forced swim test (FST) and prevented degeneration of astrocytes in the mPFC. The mechanism of antidepressant and glioprotective effects of Lu AA33810 has not been studied, so far. We demonstrated the contribution of the noradrenergic rather than the serotonergic pathway to the antidepressant-like action of Lu AA33810 in the FST. Moreover, we found that antidepressant-like effect of Lu AA33810 was connected with the influence on brain-derived neurotrophic factor (BDNF) protein expression. We also demonstrated the antidepressant-like effect of Lu AA33810 in the FST in rats which did not receive the gliotoxin. We found that intracerebroventricular injection of the selective MAPK/ERK inhibitor U0126 (5 μg/2 μl) and the selective PI3K inhibitor LY294002 (10 nmol/2 μl) significantly inhibited the anti-immobility effect of Lu AA33810 in the FST in rats, suggesting that MAPK/ERK and PI3K signaling pathways could be involved in the antidepressant-like effect of Lu AA33810.

CONCLUSION

Our results indicate that Lu AA33810 exerts an antidepressant-like effect and suggest the Y5 receptors as a promising target for antidepressant therapy.

Disseminated aspergillosis in an immunocompetent patient with detectable bis(methylthio)gliotoxin and negative galactomannan

BACKGROUND

Disseminated invasive aspergillosis is an exceptional finding in immunocompetent hosts. As in immunocompromised patients, it has high mortality rates. Early diagnostic methods are required in order to properly manage the patient. Bis(methylthio)gliotoxin (bmGT) is a novel biomarker, useful in onco-hematological patients.

CASE REPORT

A 70-year-old male, with non-insulin dependent type II diabetes mellitus and a past surgery history of aortic valve replacement with coronary by-pass five years ago, was seen in the emergency department with blurred vision. Three days later, endogen endophthalmitis was diagnosed in the ophthalmology clinic. During admission for the vitrectomy, he suffered an ischemia of the right lower limb. A thoracic computed tomography revealed a mycotic aneurysm of the ascending thoracic aorta and parietal thrombus. The ascending aorta was replaced and abundant brittle material of infectious appearance, found between the aortic valve graft and the aneurysm, was removed. Aspergillus fumigatus sensu stricto grew in both vitreous and aorta cultures. BmGT was detected in two serum samples obtained prior to intravenous antifungal treatment, which was then reduced after voriconazole treatment was started.

CONCLUSIONS

Disseminated invasive aspergillosis is a severe disease regardless of the immune status of the patient. This case report suggests that bmGT could be a suitable early diagnostic biomarker, not only in neutropenic patients, but also in immunocompetent hosts.

Clinical validity of bis(methylthio)gliotoxin for the diagnosis of invasive aspergillosis

Early and accurate diagnosis of invasive aspergillosis (IA) is one of the most critical steps needed to efficiently treat the infection and reduce the high mortality rates that can occur. We have previously found that the Aspergillus spp. secondary metabolite, bis(methylthio)gliotoxin (bmGT), can be detected in the serum from patients with possible/probable IA. Thus, it could be used as a diagnosis marker of the infection. However, there is no data available concerning the sensitivity, specificity and performance of bmGT to detect the infection. Here, we have performed a prospective study comparing bmGT detection with galactomannan (GM), the most frequently used and adopted approach for IA diagnosis, in 357 sera from 90 episodes of patients at risk of IA. Our results, involving 79 patients that finally met inclusion criteria, suggest that bmGT presents higher sensitivity and positive predictive value (PPV) than GM and similar specificity and negative predictive value (NPV). Importantly, the combination of GM and bmGT increased the PPV (100 %) and NPV (97.5 %) of the individual biomarkers, demonstrating its potential utility in empirical antifungal treatment guidance and withdrawal. These results indicate that bmGT could be a good biomarker candidate for IA diagnosis and, in combination with GM, could result in highly specific diagnosis of IA and management of patients at risk of infection.

Proteomic analyses reveal the key roles of BrlA and AbaA in biogenesis of gliotoxin in Aspergillus fumigatus

The opportunistic human pathogenic fungus Aspergillus fumigatus primarily reproduces by forming a large number of asexual spores (conidia). Sequential activation of the central regulators BrlA, AbaA and WetA is necessary for the fungus to undergo asexual development. In this study, to address the presumed roles of these key developmental regulators during proliferation of the fungus, we analyzed and compared the proteomes of vegetative cells of wild type (WT) and individual mutant strains. Approximately 1300 protein spots were detectable from 2-D electrophoresis gels. Among these, 13 proteins exhibiting significantly altered accumulation levels were further identified by ESI-MS/MS. Markedly, we found that the GliM and GliT proteins associated with gliotoxin (GT) biosynthesis and self-protection of the fungus from GT were significantly down-regulated in the ΔabaA and ΔbrlA mutants. Moreover, mRNA levels of other GT biosynthetic genes including gliM, gliP, gliT, and gliZ were significantly reduced in both mutant strains, and no and low levels of GT were detectable in the ΔbrlA and ΔabaA mutant strains, respectively. As GliT is required for the protection of the fungus from GT, growth of the ΔbrlA mutant with reduced levels of GliT was severely impaired by exogenous GT. Our studies demonstrate that AbaA and BrlA positively regulate expression of the GT biosynthetic gene cluster in actively growing vegetative cells, and likely bridge morphological and chemical development during the life-cycle of A. fumigatus.

Genetic control of asexual development in aspergillus fumigatus

Aspergillus fumigatus is one of the most common fungi found in the environment. It is an opportunistic human pathogen causing invasive pulmonary aspergillosis with a high mortality rate in immunocompromised patients. Conidia, the asexual spores, serve as the main dispersal and infection agent allowing entrance of the fungus into the host through the respiratory tract. Therefore, understanding the asexual developmental process that gives rise to the conidia is of great interest to the scientific community and is currently the focus of an immense load of research being conducted. We have been studying the genetic basis that controls asexual development and gliotoxin biosynthesis in A. fumigatus. In this review, we discuss the genetic regulatory system that dictates conidiation in this important fungus by covering the roles of crucial genetic factors from the upstream heterotrimeric G-protein signaling components to the more specific downstream central activators of the conidiation pathway. In addition, other key asexual regulators including the velvet regulators, the Flb proteins and their associated regulatory factors are discussed.

Antidepressant-like effect of the mGluR5 antagonist MTEP in an astroglial degeneration model of depression

The glutamatergic predominance in the excitatory-inhibitory balance is postulated to be involved in the pathogenesis of depression. Such imbalance may be induced by astrocyte ablation which reduces glutamate uptake and increases glutamate level in the synaptic cleft. In the present study, we tried to ascertain whether astroglial degeneration in the prefrontal cortex could serve as an animal model of depression and whether inhibition of glutamatergic transmission by the mGluR5 antagonist MTEP could have antidepressant potential. Astrocytic toxins l-or dl-alpha-aminoadipic acid (AAA), 100μg/2μl, were microinjected, bilaterally into the rat medial prefrontal cortex (PFC) on the first and second day of experiment. MTEP (10mg/kg) or imipramine (30mg/kg) were administered on the fifth day. Following administration of MTEP or imipramine the forced swim test (FST) was performed for assessment of depressive-like behavior. The brains were taken out for analysis on day eight. The astrocytic marker, glial fibrillary acidic protein (GFAP) was quantified in PFC by Western blot method and by stereological counting of immunohistochemically stained sections. Both l-AAA and dl-AAA induced a significant increase in immobility time in the FST. This effect was reversed by imipramine, which indicates depressive-like effects of these toxins. A significant decrease in GFAP (about 50%) was found after l-AAA. Both the behavioral and GFAP level changes were prevented by MTEP injection. The obtained results indicate that the degeneration of astrocytes in the PFC by l-AAA may be a useful animal model of depression and suggest antidepressant potential of MTEP.

Gliotoxin promotes Aspergillus fumigatus internalization into type II human pneumocyte A549 cells by inducing host phospholipase D activation

The internalization of Aspergillus fumigatus into lung epithelial cells is critical for the infection process in the host. Gliotoxin is the most potent toxin produced by A. fumigatus. However, its role in A. fumigatus internalization into the lung epithelial cells is still largely unknown. In the present study, the deletion of the gliP gene regulating the production of gliotoxin in A. fumigatus suppressed the internalization of conidia into the A549 lung epithelial cells, and this suppression could be rescued by the exogenous addition of gliotoxin. At lower concentrations, gliotoxin enhanced the internalization of the conidia of A. fumigatus into A549 cells; in contrast, it inhibited the phagocytosis of J774 macrophages in a dose-dependent manner. Under a concentration of 100 ng/ml, gliotoxin had no effect on A549 cell viability but attenuated ROS production in a dose-dependent manner. Gliotoxin significantly stimulated the phospholipase D activity in the A549 cells at a concentration of 50 ng/ml. This stimulation was blocked by the pretreatment of host cells with PLD1- but not PLD2-specific inhibitor. Morphological cell changes induced by gliotoxin were observed in the A549 cells accompanying with obvious actin cytoskeleton rearrangement and a moderate alteration of phospholipase D distribution. Our data indicated that gliotoxin might be responsible for modulating the A. fumigatus internalization into epithelial cells through phospholipase D1 activation and actin cytoskeleton rearrangement.

Loss of CclA, required for histone 3 lysine 4 methylation, decreases growth but increases secondary metabolite production in Aspergillus fumigatus

Secondary metabolite (SM) production in filamentous fungi is mechanistically associated with chromatin remodeling of specific SM clusters. One locus recently shown to be involved in SM suppression in Aspergillus nidulans was CclA, a member of the histone 3 lysine 4 methylating COMPASS complex. Here we examine loss of CclA and a putative H3K4 demethylase, HdmA, in the human pathogen Aspergillus fumigatus. Although deletion of hdmA showed no phenotype under the conditions tested, the cclA deletant was deficient in tri- and di-methylation of H3K4 and yielded a slowly growing strain that was rich in the production of several SMs, including gliotoxin. Similar to deletion of other chromatin modifying enzymes, ΔcclA was sensitive to 6-azauracil indicating a defect in transcriptional elongation. Despite the poor growth, the ΔcclA mutant had wild-type pathogenicity in a murine model and the Toll-deficient Drosophila model of invasive aspergillosis. These data indicate that tri- and di-methylation of H3K4 is involved in the regulation of several secondary metabolites in A. fumigatus, however does not contribute to pathogenicity under the conditions tested.

A high-performance molluscicidal ingredient against Oncomelania hupensis produced by a rhizospheric strain from Phytolacca acinosa Roxb

Background:

Snail (Oncomelania hupensis) control is an important and effective preventive strategy in schistosomiasis control programs, and screening microbial molluscicidal agents is one of the most promising categories in biomolluscicides.

Objective:

To purify and identify the molluscicidal ingredient (MI) obtained from strain SL-30's exocellular broth.

Materials and Methods:

The active extracts extracted from SL-30's exocellular broth was purified on a silica gel column guided by molluscicidal activity assay against Oncomelania hupensis, then the MI was obtained. NMR spectroscopy and LC-MS/MS analysis was used to identify the molecular structure of the MI.

Results:

Molluscicidal activity bioassay showed that the MI exhibited significant molluscicidal activity with the LC₅₀ values of 0.101, 0.062, and 0.022 mg/L, respectively, in the case of exposure period of 24 h. From ¹H NMR, ¹³C NMR, ¹H-¹H COSY, and ¹H-¹³C HSQC spectra, partial important structure fragment was obtained, and the relative molecular weight of the MI showed 326 according to LC-MS analysis. Then, on these grounds, it was indicated that the molecular structure of the MI had a higher similarity to Gliotoxin with the molecular formula of C₁₃ H₁₄N₂O₄S₂. The quasi-molecular ion of m/z 325.45 was further analyzed by MS² as the parent ion, and two daughter ions obtained at m/z 295.11 [M-CH₂OH]- and m/z 261.08 [M-CH₂OH -2S]–

Conclusion:

The MI was finally confirmed as Gliotoxin.

Regulation of Development in Aspergillus nidulans and Aspergillus fumigatus

Members of the genus Aspergillus are the most common fungi and all reproduce asexually by forming long chains of conidiospores (or conidia). The impact of various Aspergillus species on humans ranges from beneficial to harmful. For example, several species including Aspergillus oryzae and Aspergillus niger are used in industry for enzyme production and food processing. In contrast, Aspergillus flavus produce the most potent naturally present carcinogen aflatoxins, which contaminate various plant- and animal-based foods. Importantly, the opportunistic human pathogen Aspergillus fumigatus has become the most prevalent airborne fungal pathogen in developed countries, causing invasive aspergillosis in immunocompromised patients with a high mortality rate. A. fumigatus produces a massive number of small hydrophobic conidia as the primary means of dispersal, survival, genome-protection, and infecting hosts. Large-scale genome-wide expression studies can now be conducted due to completion of A. fumigatus genome sequencing. However, genomics becomes more powerful and informative when combined with genetics. We have been investigating the mechanisms underlying the regulation of asexual development (conidiation) and gliotoxin biosynthesis in A. fumigatus, primarily focusing on a characterization of key developmental regulators identified in the model fungus Aspergillus nidulans. In this review, I will summarize our current understanding of how conidiation in two aspergilli is regulated.