The life cycle of Nadsonia: A novel antifungal screen

Swart C.W., Van Wyk P.W.J., Pohl C.H., Kock L.J.L.F.

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The yeast Nadsonia fulvescens is characterized by a unique life cycle which is automictic and homothallic. After heterogamic conjugation, between the parent cell and a bud, the contents of the zygote move into another bud formed at the opposite end of the parent cell. This second bud is then delimited by a septum and becomes the ascus. Usually one, rarely two spherical brownish spiny to warty ascospores are formed with a prominent lipid globule. Using mitochondrial trans-membrane potential (delta 968;m) and β -oxidation probes as well as mitochondrial enzyme activity markers, we found increased mitochondrial activity in the mother cell during ascospore formation. This activity decreases in the presence of mitochondrial inhibitors. Similar results were found when mitochondrial products, i.e. 3-hydroxy oxylipins, were analysed using gas chromatography mass spectrometry. Strikingly, when mitochondrial inhibitors are added to this yeast, the sexual cycle is inhibited causing malformed colourless ascospores sometimes without spiny protuberances to be formed. This can easily be visualized when this yeast is used together with the agar plate diffusion method where sensitivity towards mitochondrial inhibitors is tested over a concentration gradient. At high concentrations, a white lawn of cells is formed while the lawn turns brown (amber) at lower mitochondrial inhibitor concentrations. This phenomenon may have value in the screening of mitochondrial inhibition drugs that may have various actions i.e, antifungal, anticancer and anti-inflammatory. Here, various known anti-mitochondrials with anti-inflammatory and antifungal activity were screened to define the bio-assay.

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17th International Society for Human and Animal Mycology
    • ISHAM 17th (2009)