Sugarcane: an unexpected habitat for black yeasts in Chaetothyriales.

Sugarcane (Saccharum officinarum, Poaceae) is cultivated on a large scale in (sub)tropical regions such as Brazil and has considerable economic value for sugar and biofuel production. The plant is a rich substrate for endo- and epiphytic fungi. Black yeasts in the family Herpotrichiellaceae (Chaetothyriales) are colonizers of human-dominated habitats, particularly those rich in toxins and hydrocarbon pollutants, and may cause severe infections in susceptible human hosts. The present study assessed the diversity of Herpotrichiellaceae associated with sugarcane, using in silico identification and selective isolation. Using metagenomics, we identified 5833 fungal sequences, while 639 black yeast-like isolates were recovered in vitro. In both strategies, the latter fungi were identified as members of the genera Cladophialophora, Exophiala, and Rhinocladiella (Herpotrichiellaceae), Cyphellophora (Cyphellophoraceae), and Knufia (Trichomeriaceae). In addition, we discovered new species of Cladophialophora and Exophiala from sugarcane and its rhizosphere. The first environmental isolation of Cladophialophora bantiana is particularly noteworthy, because this species up to now is exclusively known from the human host where it mostly causes fatal brain disease in otherwise healthy patients.

MG-Pe: A Novel Galectin-3 Ligand with Antimelanoma Properties and Adjuvant Effects to Dacarbazine.

Melanoma is a highly metastatic and rapidly progressing cancer, a leading cause of mortality among skin cancers. The melanoma microenvironment, formed from the activity of malignant cells on the extracellular matrix and the recruitment of immune cells, plays an active role in the development of drug resistance and tumor recurrence, which are clinical challenges in cancer treatment. These tumoral metabolic processes are affected by proteins, including Galectin-3 (Gal-3), which is extensively involved in cancer development. Previously, we characterized a partially methylated mannogalactan (MG-Pe) with antimelanoma activities. In vivo models of melanoma were used to observe MG-Pe effects in survival, spontaneous, and experimental metastases and in tissue oxidative stress. Analytical assays for the molecular interaction of MG-Pe and Gal-3 were performed using a quartz crystal microbalance, atomic force microscopy, and contact angle tensiometer. MG-Pe exhibits an additive effect when administered together with the chemotherapeutic agent dacarbazine, leading to increased survival of treated mice, metastases reduction, and the modulation of oxidative stress. MG-Pe binds to galectin-3. Furthermore, MG-Pe antitumor effects were substantially reduced in Gal-3/KO mice. Our results showed that the novel Gal-3 ligand, MG-Pe, has both antitumor and antimetastatic effects, alone or in combination with chemotherapy.

Microscopic analysis of colonization of Colletotrichum abscissum in citrus tissues.

Postbloom fruit drop (PFD), caused mainly by Colletotrichum abscissum, is one of the most severe citrus diseases and can causes up to 80% fruit loss in favorable climatic conditions. According to the literature, other Colletotrichum species colonize hosts using distinct strategies: intracellular hemibiotrophic or subcuticular intramural necrotrophic colonization. However, so far, for C. abscissum only the necrotrophic stage has been described and some aspects remain unclear in PFD disease cycle. To better understand the disease cycle, microscopy studies could be applied. However, even using eGFP strains (expressing green fluorescent protein), the results are unclear due to the autofluorescence of citrus leaves. To eliminate this problem and to study the interaction between C. abscissum-citrus we used a destaining and staining methodologies, and we observed that in leaves, even applying injury before inoculation, C. abscissum does not colonize adjacent tissues. Apparently, in the leaves the fungus only uses the nutrients exposed in the artificial lesions for growth, and then produces large amount of spores. However, in flowers, C. abscissum penetrated and colonized the tissues of the petals 12 h after inoculation. In the early stages of infection, we observed the development of primary biotrophic hyphae, suggesting this species as a hemibiotrophic fungus, with a short biotrophic phase during flower colonization followed by dominant necrotrophic colonization. In conclusion, the use of an eGFP strain of C. abscissum and a different methodology of destaining and staining allowed a better understanding of the morphology and mechanisms used by this citrus pathogen to colonize the host.

A Model for Trans-Kingdom Pathogenicity in Fonsecaea Agents of Human Chromoblastomycosis.

The fungal genus Fonsecaea comprises etiological agents of human chromoblastomycosis, a chronic implantation skin disease. The current hypothesis is that patients acquire the infection through an injury from plant material. The present study aimed to evaluate a model of infection in plant and animal hosts to understand the parameters of trans-kingdom pathogenicity. Clinical strains of causative agents of chromoblastomycosis (Fonsecaea pedrosoi and Fonsecaea monophora) were compared with a strain of Fonsecaea erecta isolated from a living plant. The clinical strains of F. monophora and F. pedrosoi remained concentrated near the epidermis, whereas F. erecta colonized deeper plant tissues, resembling an endophytic behavior. In an invertebrate infection model with larvae of a beetle, Tenebrio molitor, F. erecta exhibited the lowest survival rates. However, F. pedrosoi produced dark, spherical to ovoidal cells that resembled muriform cells, the invasive form of human chromoblastomycosis confirming the role of muriform cells as a pathogenic adaptation in animal tissues. An immunologic assay in BALB/c mice demonstrated the high virulence of saprobic species in animal models was subsequently controlled via host higher immune response.