SOS/umu-Test as A Tool for Genotoxicity Assessment By 劉文堅 Advisor: 袁如馨...
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Transcript of SOS/umu-Test as A Tool for Genotoxicity Assessment By 劉文堅 Advisor: 袁如馨...
SOS/umu-Test as
A Tool for Genotoxicity Assessment
By 劉文堅Advisor: 袁如馨防災與水環境研究中心
Why umu-test ? A low cost experiment assay: no high cost chemicals
and complicated apparatus is needed in conducting the experiment.
High-throughput: umu-test enable high amount of sample to be tested at a time.
Short time requirement: umu-test utilizes bacteria which has short life cycle.
High sensitivity: accuracy of umu-test has been proven
Theory of umu-test
β-galactosidase
IR calculation
Mutagen exposure
Sos response
umuC-LacZ fused protein
translation
Enzyme production
ONPG o-nitrophenyl(colourless) (Yellow-colored)
Absorbance measurement
• Firstly, Salmonella typhimuium TA1535/pKK1002 will be exposed to genotoxicants
• As soon as the bacteria senses genotoxicity existance, SOS response is transmitted to produce umuC-LacZ fused protein
• The protein will produce β-galactosidase• ONPG is used as color indicator• ONPG (colorless) will be converted into o-
nitrophenyl (yellow color) by the existance of β-galactosidase
• Absorbance measurement is done under spectrophotometer
• The amount of β-galactosidase correlates to the level of toxicity
• Induction ratio obtained by calculation
Genotoxicity test of 4-NQO
The recent conducted toxicity test result on 4-NQO (well known genotoxicants) indicates the ability of umu test in toxic assessment.
The Dashed line represent concentration of 4-NQO at 2-fold greater than the control response, which tells us every black point (IR point) that is higher than the dashed line are considered to be genotoxic.
4-NQO (mg/L)
1052.
51.
250.
625
0.31
25
0.15
625
0.07
815
-g
alac
tosi
das
e ac
tivi
ty (
un
it)
0
200
400
600
800
1000
1200
1400
1600
1800
Ind
uct
ion
rat
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0
2
4
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14
-galactosidase activityInduction ratio
Future Study Application of umu-test on various toxic samples in
the environment. Continuous cooperation with the inventor of the
umu-test to increase the efficiency of the test by experimenting on different strains of Salmonella.
Comparison of the genotoxicity result by umu-test with those by Comet assay, to establish the database of potential genotoxicants from industrial wastewater.