Unit:
Faculty of MedicineLibrary of the School of Health Sciences
Author:
Μargaritou Aikaterini
Dissertation committee:
Κωνσταντίνος Πάντος, Καθηγητής, Ιατρική Σχολή, ΕΚΠΑ, Επιβλέπων
Νικόλαος Καβαντζάς, Καθηγητής, Ιατρική Σχολή, ΕΚΠΑ
Δημήτριος Κυριακίδης, Καθηγητής, Τμήμα Χημείας, ΑΠΘ
Αναστάσιος Φιλίππου, Αναπληρωτής Καθηγητής, Ιατρική Σχολή, ΕΚΠΑ
Αναστασία Δέτση, Αναπληρώτρια Καθηγήτρια, Σχολή Χημικών Μηχανικών ΕΜΠ
Ιορδάνης Μουρούζης, Επίκουρος Καθηγητής, Ιατρική Σχολή, ΕΚΠΑ
Δημήτριος Τραφαλής, Επίκουρος Καθηγητής, Ιατρική Σχολή, ΕΚΠΑ
Original Title:
Χημικοί περιβαλλοντικοί παράγοντες και κυτταρική απάντηση: φαρμακολογική και επιγενετική προσέγγιση.
Translated title:
Chemical environmental agents and cellular response : pharmacological and epigenetic approach.
Summary:
Although tributyltin (TBT) is a widespread environmental pollutant, its effects at the cellular level has not been adequately studied. The unicellular eukaryote S. cerevisiae is considered as a appropriate model organism for the study of the effects of TBT on eukaryotic cells.
The aim of this study was to investigate the effects of TBT on the growth, proliferation, survival, morphology and metabolic profile of S. cerevisiae as well as the development of potential epigenetic alterations and/or adaptive mechanisms after TBT exposure. Ultimately, this study sought to explore the putative interactions of TBT with the biological processes in eukaryotic cells and organisms.
The experimental approach included single and/or repeated administration of different TBT dosages (5.0-31.5 μM) in asynchronous cultures of S. cerevisiae ATCC 2366 during the lag, logarithmic and/or stationery phase of growth. The yeast response was evaluated under the optical microscope, mainly by determining the total cell number, the proportion of the budded and living cells and any morphological changes, while the metabolic profile was investigated by the spectrophotometric determination of carbohydrates using the anthrone method.
The results showed a dose-dependent inhibition of growth, survival and proliferation of yeast cells upon TBT administration during the lag and the logarithmic phase. No effect was observed during administration at the stationery phase. Interestingly, shortly after exposure to TBT, live aberrant cells appeared, characterized by large cytoplasmic structures that referred to vacuoles. Also, the increase of glycogen and trehalose levels at the post-logaritmic phase of growth of cells exposed to TBT, were indicative of the selective action of the compound on the growth rate of yeast. Yet, the determination of the kinetic characteristics of TBT actions remain elusive.
The obtained data provided evidence for the inhibitory action of TBT, mainly on the rapidly proliferating cells, where V ATPase inhibition likely prevented vacuole acidification and lead to cell cycle arrest. The effect of TBT was cumulative and the cellular subpopulation that survived was capable to proliferate and to overcome the toxic effects of TBT at the post-logarithmic phase of growth. Finally, in the S. cerevisiae strain used in this study, TBT did not seem to cause any epigenetic alterations associated with “petite” mutations. Interestingly, the preliminary findings related to the development of the potentially protective cellular stress response during chronic exposure of yeast to subtoxic TBT concentrations deserve further consideration.
Main subject category:
Health Sciences
Keywords:
Tributyltin, TBT, Cellular response, Saccharomyces cerevisiae
Number of references:
247
