Banca de QUALIFICAÇÃO: RONALD MURYELLISON OLIVEIRA DA SILVA GOMES

Uma banca de QUALIFICAÇÃO de MESTRADO foi cadastrada pelo programa.
STUDENT : RONALD MURYELLISON OLIVEIRA DA SILVA GOMES
DATE: 24/03/2023
TIME: 09:00
LOCAL: Sala Carl Peter von Dietrich
TITLE:

Use of group I íntrons from the mitogenome of Cryptococcus neoformans and Cryptococcus gattii for species identification and their association with antifungal susceptibility

KEY WORDS:

Cryptococcosis, group I íntrons, cryptic species, cob, cox1, antifungals.

PAGES: 105
BIG AREA: Ciências Biológicas
AREA: Bioquímica
SUMMARY:

The Cryptococcus neoformans and Cryptococcus gattii species complexes are composed of pathogenic fungi that kill more than 180,000 people annually worldwide, with meningoencephalitis being the main symptom of cryptococcosis. Features such as virulence and susceptibility to antifungals can vary within each species according to the fungal genotype: C. neoformans is divided into molecular types VNI, VNII, VNIII, and VNIV and C. gattii into VGI, VGII, VGIII, and VGIV. Therefore, a differential diagnosis with specific molecular markers is necessary and urgent. Group I self-splicing íntrons may be a potential target for molecular type distinction of these yeasts, as they have polymorphisms regarding their presence and sequence of base pairs. Moreover, since the auto-splicing of these elements is vital for the fungal cell, they are considered important therapeutic targets, as they are absent from the human genome. Based on this, this project aimed to evaluate the presence of group I íntrons in the mitochondrial genes cob and cox1 of Cryptococcus fungal isolates, investigate the potential use of these genetic elements as molecular markers for genotype-specific diagnosis and their relationship with antifungal susceptibility, as well as study their origin, distribution, and evolution through phylogenetic analyses. The data obtained from the amplification of íntrons of the cob and cox1 genes showed that the C. neoformans complex has, on average, fewer íntrons in its mitogenome, and there is a large polymorphism of presence and size of these elements between and within genotypes, which makes it impossible to use a single íntronic marker to differentiate genotype and/or species in the C. neoformans and C. gattii complexes. However, species differentiation is possible with combinations of PCRs of mtLSU and cox1 íntrons for C. neoformans species and mtLSU and cob íntrons for C. gattii. Phylogenetic analyses showed that íntrons occupying the same insertion site form monophyletic clades and probably have a common ancestor, an íntron that invaded this site before the species divergence. There was only one case of heterologous invasion probably resulting from horizontal transfer between a VGIV genotype isolate and the lichenized fungus species Arthonia susa. In antifungal susceptibility assays, it was observed that the minimum inhibitory concentration values of Fluconazole, 5-Flucytosine, and Pentamidine were statistically associated with species complexes, with C. gattii having higher MICs for Fluconazole and C. neoformans having higher MICs for 5-Flucytosine and Pentamidine. The presence of íntrons was related to susceptibility to Amphotericin-B, for which a higher amount of íntrons was associated with lower MIC values, and to 5-Flucytosine and Pentamidine, for which the influence of íntron presence varied between complexes: regarding 5-Flucytosine, íntron presence was related to lower susceptibility in C. neoformans and higher in C. gattii, and the opposite scenario was observed for Pentamidine, for which íntrons were associated with higher susceptibility in C. neoformans and lower in C. gattii.

COMMITTEE MEMBERS:
Externo à Instituição - DIOGO GARCIA VALADARES - UIOWA
Interna - 1549705 - ADRIANA FERREIRA UCHOA
Presidente - 1453487 - KATIA CASTANHO SCORTECCI