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HORMESIS IN YEAST PowerPoint PPT Presentation

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0 mg (Control). HORMESIS IN YEAST. Cao Tian Qin, Tham Shi Yuan, Lim Yuan Wei. Exposure of yeast to other stressor agents, e.g. antibiotics. Hwa Chong Institution. ABSTRACT. OBJECTIVES. INTRODUCTION.

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Hormesis in yeast

0 mg (Control)


Cao Tian Qin, Tham Shi Yuan, Lim Yuan Wei

  • Exposure of yeast to other stressor agents, e.g. antibiotics

Hwa Chong Institution




This project investigates the phenomenon of hormesis in the yeast, Saccharomycescerevisiae. The principle of hormesis applies to the stimulation of growth in the presence of low dosage of stressor agents. High concentrations of Paracetamol and Traditional Chinese Medicine, Angelica sinensis, were shown to inhibit growth of yeast. However, at low concentrations, growth of yeast was stimulated in the presence of Paracetamol and TCM and a mixture of both. This was carried out by growing the yeast in broth cultures supplemented with varying concentrations of Paracetamol or TCM, serially diluting the yeast cultures and plating on potato dextrose medium. The number of colonies was then determined. Polyacrylamide gel electrophoresis analysis indicated an alteration in the expression of genes, leading to new proteins synthesized in the presence of low dosages of stressor agents. These findings can be applied commercially in which yeast growing in fermenters in the production of beer can be stimulated with such stressor agents, thus increasing the yield.

  • To find out if the principle of hormesis applies to yeast cells when low dosages of both Western Medicine and Traditional Chinese Medicine are applied, as measured by the growth rate of yeast

  • To investigate the effect of low dosages of Paracetamol on protein synthesis in yeast

  • Hormesis is the name given to the stimulatory effects caused by low levels of potentially toxic agents (Hadley, 2003).

  • Process whereby the application of stressor agents in low doses to a subject stimulates a subjective beneficial response, typically in the form of resource allocation in the biological system (Calabrese and Baldwin, 2002).

  • A typical hormetic curve has an inverted U-shaped dose-response if growth is measured (Calabrese, 2004).


  • Low dosages of Paracetamol and Traditional Chinese Medicine such as Angelica sinensis will induce a higher rate of growth in yeast cells

  • Low dosages of Paracetamol induce the synthesis of new proteins in yeast


Extraction of proteins from yeast

Growth of yeast with Paracetamol and TCM

Preparation of Paracetamol and TCM

Preculture of yeast


Effect of high concentration of Paracetamol and TCM on growth of yeast

Hormetic effect of Paracetamol on growth of yeast

0 mg (control)

3 mg

60 mg

150 mg

At a high amount (300 mg) of Paracetamol and TCM, inhibition of yeast growth was observed. Both are stressor agents.

15 mg

30 mg

300 mg

450 mg

Yeast growth was stimulated the most when 3 mg Paracetamol added to 30 ml PD broth.

Hormetic effect of TCM on growth of yeast

Effect of Paracetamol on protein synthesis in yeast

Marker 0 3 15 30 60 150 300 450 mg

3 mg TCM


Yeast growth was stimulated when 3, 15 and 30 mg added to 30 ml PD broth.


Further Work

Hormetic effect of mixture on growth of yeast

3 mg

0 mg

15 mg


15 mg TCM

30 mg TCM

  • Balzan, R., Sapienza, K., Galea, D.R., Vassallo, N., Frey, H. & Bannister, W.H. (2004). Aspirincommitsyeastcells to apoptosisdepending on carbon source. Microbiology, 150, 109-115.

  • Calabrese, E.J. (2004). Hormesis: a revolution in toxicology, risk assessment and medicine. EMBO Reports, 5, S37 – S40.  

  • Calabrese, E.J. & Baldwin, L.A (2002). Defining hormesis. Human and Experimental Toxicology, 21, 91-97. 

  • Hadley, C. (2003). What doesn’t kill you makes you stronger. EMBO Reports, 4, 924-926.


60 mg

30 mg



The mixture of stimulated growth of yeast at all concentrations tested significantly (t-test p value < 0.05).

Stimulation of growth by 30 mg of mixture of Paracetamol and TCM was the highest (4.01 x above control).

Mrs Goh-Yip Cheng Wai, project mentor

Mdm Lim Cheng Fui, Science Research Centre,

Hwa Chong Institution

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