Production of trichothecene mycotoxins by Australian Fusarium species

The Protective Effect of Selenium on T-2-Induced Nephrotoxicity Is Related to the Inhibition of ROS-Mediated Apoptosis in Mice Kidney

T-2 toxin is produced by the Fusarium genus. Ingestion of food or feed contaminated by T-2 toxin will cause damage to kidney. Selenium (Se), an essential trace element, showed the significant protective effects against kidney and renal cell damage induced by toxic substances. To explore the protective effects and mechanisms of Se against T-2-induced renal lesions, forty-eight male Kunming mice were exposed to T-2 toxin (1.0 mg/kg) and/or Se (0.2 mg/kg) for 28 days. In this study, we found that Se alleviated T-2-induced nephrotoxicity, presenting as increasing the body weight and kidney coefficient, relieving the renal structure injury, decreasing the contents of renal function-related biomarkers, decreasing the levels of reactive oxygen species (ROS), and increasing the mitochondrial membrane potential in T-2 toxin-treated mice. In addition, inhibition of renal cell apoptosis by Se was associated with blocking the mitochondrial pathway in T-2 toxin-treated mice, presenting as decreasing the protein expression of cytochrome-c, activities of caspase-3/9, as well as regulating the protein and mRNA expressions of Bax and Bcl-2. These results documented that the alleviating effect of Se on T-2-induced nephrotoxicity is related to the inhibition of ROS-mediated renal apoptosis.

T-2 toxin upregulates the expression of human cytochrome P450 1A1 (CYP1A1) by enhancing NRF1 and Sp1 interaction

T-2 toxin is a major pollutant in crops and feedstuffs. Due to its high toxicity in a variety of organisms, T-2 toxin is of great concern as a threat to humans and to animal breeding. Overexpression of CYP1A1 may contribute to carcinogenesis, and CYP1A1 may be a promising target for the prevention and treatment of human malignancies. Therefore, it is essential to understand the regulatory mechanism by which T-2 toxin induces CYP1A1 expression in human cells. In this study, we confirmed that T-2 toxin (100 ng/mL) induced the expression of CYP1A1 in HepG2 cells through NRF1 and Sp1 bound to the promoter instead of through the well-recognized Aromatic hydrocarbon receptors (AhR). In cells treated with T-2 toxin, Sp1, but not NRF1, was significantly upregulated. However, T-2 toxin apparently promoted the interaction between NRF1 and Sp1 proteins, as revealed by IP analysis. Furthermore, in T-2 toxin-treated HepG2 cells, nuclear translocation of NRF1 was enhanced, while knockdown of Sp1 ablated NRF1 nuclear enrichment. Our results revealed that the upregulation of CYP1A1 by T-2 toxin in HepG2 cells depended on enhanced interaction between Sp1 and NRF1. This finding suggests the tumorigenic features of T-2 toxin might be related to the CYP1A1, which provides new insights to understand the toxicological effect of T-2 toxin.

miR449a/SIRT1/PGC-1α Is Necessary for Mitochondrial Biogenesis Induced by T-2 Toxin

T-2 toxin is one of the type A trichothecenes produced mainly by the Fusarium genus. Due to its broad distribution and highly toxic nature, it is of great concern as a threat to human health and animal breeding. In addition to its ribotoxic effects, T-2 toxin exposure leads to mitochondrial dysfunction, reactive oxygen species (ROS) accumulation and eventually cell apoptosis. We observed that mitochondrial biogenesis is highly activated in animal cells exposed to T-2 toxin, probably in response to the short-term toxic effects of T-2 toxin. However, the molecular mechanisms of T-2 toxin-induced mitochondrial biogenesis remain unclear. In this study, we investigated the regulatory mechanism of key factors in the ROS production and mitochondrial biogenesis that were elicited by T-2 toxin in HepG2 and HEK293T cells. Low dosages of T-2 toxin significantly increased the levels of both mitochondrial biogenesis and ROS. This increase was linked to the upregulation of SIRT1, which is controlled by miR-449a, whose expression was strongly inhibited by T-2 toxin treatment. In addition, we found that T-2 toxin-induced mitochondrial biogenesis resulted from SIRT1-dependent PGC-1α deacetylation. The accumulation of PGC-1α deacetylation, mediated by high SIRT1 levels in T-2 toxin-treated cells, activated the expression of many genes involved in mitochondrial biogenesis. Together, these data indicated that the miR449a/SIRT1/deacetylated PGC-1α axis plays an essential role in the ability of moderate concentrations of T-2 toxin to stimulate mitochondrial biogenesis and ROS production.

Fusarium toxins of the scirpentriol subgroup: a review

Scirpentriol and its seven acetylated derivatives comprise a family of type-A trichothecene toxins produced by several species of Fusarium fungi. Out of this group 4,15-diacetoxyscirpenol has attracted most attention. It elicits toxic responses in several species and was detected in a variety of substrates. Out of the three possible monoacetylated derivatives 15-monoacetoxyscirpenol and the parent alcohol scirpentriol received some attention, whereas the remaining members of the family were mentioned in few reports. The present review deals with the structure, biosynthesis, analysis and toxicity of scirpentriol toxins. Formation by Fusarium species as well as culture conditions used for toxigenicity studies are reviewed; data about the natural occurrence of scirpentriol toxins in different cereal types, cereal associated products as well as in non-grain matrices including potato and soya bean are reported. Basing on literature reports about the toxicity of scirpentriol toxins an attempt is made to summarise the state of knowledge for risk evaluation for human and animal health.

Morphological, chemical and molecular differentiation of Fusarium equiseti isolated from Norwegian cereals

The morphological variation, secondary metabolite profiles and restriction fragment length polymorphisms (RFLPs) of PCR amplified intergenic spacer (IGS) ribosomal DNA (rDNA) were studied in 27 isolates of Fusarium equiseti, 25 isolated from Norwegian cereals and 2 from soil obtained from the IBT culture collection (BioCentrum, Technical University of Denmark). All 27 isolates were tested for production of fusarochromanone (FUSCHR), zearalenone (ZEA) and the trichothecenes: 15-monoacetoxy-scirpentriol (MAS), diacetoxy-scirpenol (DAS), T-2 and HT-2 toxins, T2-triol, neosolaniol (NEO), deoxynivalenol (DON), nivalenol (NIV) and 4-acetylnivalenol (Fus-X). The trichothecenes were analysed by GC-MS in a selected ion monitoring mode, while FUSCHR was determined by ion pair HPLC with fluorometric detection and production of ZEA by TLC. For amplification of IGS rDNA primers CNL12 and CNS1 were applied. IGS rDNA was digested with the four restriction enzymes: AvaII, CfoI, EcoRI and Sau3A. In addition, we sequenced the IGS rDNA region of three of the Norwegian isolates. There were two morphological types among the Norwegian strains of F. equiseti, type I with short apical cells (dominating) and type II with long apical cells, with four haplotypes identified based on the RFLP data. Variation in secondary metabolite profiles within and between the morphological groups was observed and the levels of produced toxins were: FUSCHR 3000-42,500 and 25-30 ng/g, NIV 20-2500 and 120-700 ng/g, FUS-X 20-15,000 and 0 ng/g, DAS 30-7500 and 0-600 ng/g, and MAS 10-600 and 0-500 ng/g, for strains with short and long apical cells, respectively. NEO was detected in 16/27 strains tested (all morphotype I). All but four strains of type I (these four lacked a restriction site for EcoRI) had identical RFLP profiles. The isolates of type II had two haplotypes. The IGS sequence similarity data indicated differences between these morphotypes corresponding to two separate lineages apparently at the species level.

Production of trichothecenes and other secondary metabolites by Fusarium culmorum and Fusarium equiseti on common laboratory media and a soil organic matter agar: an ecological interpretation

Fusarium culmorum and F. equiseti were characterized with regard to production of trichothecenes and other secondary metabolites. Results following growth on laboratory media are interpreted with the aim of increasing the understanding of fungal metabolism in the field environment. While trichothecene production was detected for 94 of 102 F. culmorum isolates, only 8 of 57 F. equiseti isolates were positive. Profiles of secondary metabolites were compared by following growth on yeast extract sucrose agar (YES), potato sucrose agar (PSA), and an agar medium, prepared from soil organic matter (SOM), which was included to simulate growth conditions in soil. SOM supported the production of chrysogine by F. culmorum. The two species utilized the media differently. F. culmorumproduced zearalenone (ZEA) on YES, whereas some F. equiseti isolates produced ZEA on PSA. Other F. equiseti isolates produced equisetin. These differences may reflect that F. culmorum depends on a pathogenic life style while F. equiseti has a more saprotrophic mode of existence.

Production of trichothecenes and zearalenone by isolates of Fusarium spp. from Argentinian maize

Fusarium cultures (27 isolates of Fusarium graminearum, 5 of F. sporotrichioides, 5 of F. semitectum, 2 of F. solani, and one isolate of F. equiseti, F. heterosporum and F. oxysporum respectively, from maize ears) were screened to determine their ability to produce different trichothecenes and zearalenone. Twenty of 27 F. graminearum isolates produced deoxynivalenol (384-5745 micrograms/kg), 7/27 produced 3-acetyl-deoxynivalenol (322-1840 micrograms/kg), 3/27 produced neosolaniol (199-898 micrograms/kg), 5/27 produced diacetoxyscirpenol (205-3095 micrograms/kg), 4/27 produced HT-2 toxin (278-1377 micrograms/kg) and 13/27 produced zearalenone (200-35045 micrograms/kg). No isolate of F. graminearum produced either nivalenol, 15-acetyl-deoxynivalenol, T-2 tosin, T-2 triol or T-2 tetraol. Only chemotype IA (deoxynivalenol and 3-acetyl-deoxynivalenol) was observed. F. sporotrichioides isolates produced deoxynivalenol (5/5), T-2 triol and T-2 tetraol (1/5) and zearalenone (1/5). One F. semitectum isolate produced diacetoxyscirpenol and F. equiseti and F. oxysporum isolates produced only deoxynivalenol. Thus, three of the toxins studied, deoxynivalenol, zearalenone and 3-acetyl-deoxynivalenol are most likely to appear as contaminants in freshly harvested maize.