Tuesday, May 30 2023
14:00 - 15:00

Alladi Ramakrishnan Hall

Evolution and its role in DNA, centromeres and speciation (Pre-synopsis talk)

S Pavitra


This thesis work focuses on understanding evolutionary aspects to explain mechanisms from two different biological systems of study: speciation of a fungal pathogen and evolution of transcription factor
binding sites.

In the first part of the talk, I would be describing about a fungal pathogen, Candida auris, that is fast gaining global concern due to its healthcare-associated outbreaks. First isolated from an infected ear of a patient in Japan in 2009, C.auris emerged as a multidrug-resistant opportunistic fungal pathogen causing hospital-borne infections worldwide in a short time span.The mechanisms that underlie the sudden emergence and spread of C.auris as distinct geographical clades, though mostly unknown, represent rapid evolution modes in a fungal pathogen. Towards this, we investigate the role of centromeric regions in these species across the four known clades and trace back the plausible evolutionary path taken by this species. Consequent to this rapid evolution, recently reported strains are indicating cross identification within the previously defined four distinct geographical clades.We propose a rapid and specific colony PCR-based clade identification system (CLaID) that uses unique DNA sequence junctions conserved in clade-specific manner for the classification of newly found strains of C.auris.

In the second part of the thesis, we have studied the position specific evolution of transcription factor binding sites. Here, we model the changes in the binding sites by taking information from orthologous regions from different species and use evolutionary models namely, the Felsenstein 1981(F81) and Hasegawa-Kishino-Yano 1985 (HKY85) models of DNA evolution,to study the selective pressures that could be acting and driving the observed changes in the TFBSs. A fast implementation of likelihood calculation using the F81 model is demonstrated.

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Meeting ID: 982 0647 2628
Passcode: 560304

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