Banca de DEFESA: RONALD MURYELLISON OLIVEIRA DA SILVA GOMES

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
STUDENT : RONALD MURYELLISON OLIVEIRA DA SILVA GOMES
DATE: 20/04/2023
TIME: 14:00
LOCAL: Videoconferencia - Link para acesso: https://meet.google.com/msp-xdxs-gdr
TITLE:

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

KEY WORDS:

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

PAGES: 108
BIG AREA: Ciências Biológicas
AREA: Bioquímica
SUMMARY:

The species complexes of Cryptococcus neoformans and Cryptococcus gattii are composed of pathogenic fungi that kill over 180,000 people annually worldwide, having meningoencephalitis as the main symptom of cryptococcosis. Characteristics such as virulence and antifungal susceptibility can vary within each species according to fungal genotype: C. neoformans is divided into molecular types VNI, VNII, VNIII, and VNIV, and C. gattii into VGI, VGII, VGIII, and VGIV. Therefore, specific molecular markers are necessary for differential diagnosis. Autocatalytic group I introns can be a potential target for distinguishing between molecular types of these yeasts, as they have polymorphisms regarding their presence and base pair sequences. Furthermore, since the auto-splicing of these elements is vital for the fungal cell, they are considered important therapeutic targets since they are absent from the human genome. Therefore, this study aimed to evaluate the presence of group I introns in the mitochondrial cob and cox1 genes of Cryptococcus fungal isolates, search for ORFs with endonuclease genes in intronic sequences, investigate the potential use of these genetic elements as molecular markers for differentiation of genotypes and/or species, and analyze their relationship with antifungal susceptibility andin addition to study their origin, distribution, and evolution through phylogenetic analyses. The data obtained from intron amplification of cob and cox1 genes showed that the C. neoformans complex has, on average, fewer introns in its mitogenome, and there is a great polymorphism of presence and size of these elements among and within genotypes, making it impossible to use a single intronic marker to differentiate genotype and/or species in the C. neoformans and C. gattii complexes. However, differentiation between species is possible with combinations of PCRs of mtLSU and cox1 introns for C. neoformans species and mtLSU and cob introns for C. gattii. Approximately 80.5% of the sequenced introns had homing endonucleases, and phylogenetic analyses showed that introns occupying the same insertion site form monophyletic clades and probably have a common ancestor that invaded this site before the species diverged. There was only one case of heterologous invasion, probably originating from horizontal transfer between a VGIV genotype isolate and the lichenized fungus Arthonia susa. Regarding susceptibility assays to antifungal agents, it was observed that the minimum inhibitory concentration (MIC) 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 introns was related to susceptibility to Amphotericin B, for which a higher number of introns was associated with lower MIC values, and to 5-Flucytosine and Pentamidine, for which the influence of the presence of introns varied between complexes: regarding 5-Flucytosine, the presence of introns was related to lower susceptibility in C. neoformans and higher in C. gattii, and the opposite scenario was observed for Pentamidine, for which introns were associated with higher susceptibility in C. neoformans and lower in C. gattii.

COMMITTEE MEMBERS:
Externo à Instituição - MARCUS DE MELO TEIXEIRA - UnB
Presidente - 1997012 - RAQUEL CORDEIRO THEODORO
Interna - 1199127 - SILVIA REGINA BATISTUZZO DE MEDEIROS
Externa ao Programa - 2121234 - VANIA SOUSA ANDRADE - null