Silver chloride decompose

Silver chloride is an usual chemical compound which was used in photography. Silver chloride is a white substance, it could be prepared through silver nitrate to react with sodium chloride solution. In this reaction, silver chloride would precipitate under the vessel.

                                         Silver chloride precipitates under the vessel

Silver chloride is very sensitive to UV light(high energy radiations), because the bonds between silver ions and chlorine ions are weak so when silver chloride is under exposure with light it would decompose quickly.

                              Use filter paper to separate silver chloride from the solusion

                                             Applied silver chloride over the filter paper

                                           Put one dollar NT on the paper to be a cover,
                                           and use UV light to react with silver chloride.

                                          Silver chloride turn into dark after UV exposure

Ames test - Salmonella Reversion Assay

The Ames test is a short-term assay to assess the mutagenic potential of chemical compounds. In this experiment, we use Salmonella typhimurium (His-) to be the tester, so that it is also called "Salmonella reversion assay".

These kinds of bacterium carry mutations in genes involved in histidine synthesis, so that they require histidine for growth.(Without histidine they would not live)

We chose  TA102 (a kind of Salmonella) to be tester, and handled with two negative controls and two positive controls.

The two negative controls are Water-TA102 and DMSO-TA102, and the positive controls are Mitomycin C (-S9) and 2-Anthramine (+S9)

Mitomycin C is a anti-tumor medicine and 2-Anthramine is a chemical compound that may cause cancer.

And here the S-9 fraction is a substance extracted from liver, it contains many kinds of enzymes. We use the S-9 fraction to stimulate the metabolism of a liver. Then we could know if the substance that a liver metabolized would be a mutagen.

                                                                     S-9 fractions
                                                               

After we mixed some histidine/biotin,TA102,mutagen with S-9 and without S-9 and top agar. We poured the mixture onto each MA plates separately. Then put all plates into an oven (37oC) for three days.

                                                          After three days cultivate

Finally, we have count out all the CFU(colony-forming unite) the calculate if the positive controls is two times or higher more than the negative controls, that we can assure if an agent is a mutagen.

                                                Mitomycin C is exactly a mutagen

Experimental Record

Group 3	Plate1 (CFU)	Plate2 (CFU)	Plate3 (CFU)	Average(CFU)
Water	98	105	107	103
DMSO	150	113	183	149
Mitomycin C	670	851	767	763
2-Anthramine	239	174	181	198

Analysis

Group 3	Ratio with water	Mutagen
Mitomycin C (solvent:water)	7.408	YES
2-Anthramine (solvent:DMSO)	1.329	NO

Data of Whole the Class
G1				Average
NC (-S9)	160	65	78	101
PC (-S9)	513	334	624	490.3
NC (+S9)	232	6	237	158.3
PC (+S9)	178	184	181	181
G2
NC (-S9)	131	167	192	163.3
PC (-S9)	437	302	368	369
NC (+S9)	481	327	303	370.3
PC (+S9)	362	387	423	390.7
G3
NC (-S9)	98	105	107	103.3
PC (-S9)	670	851	767	762.7
NC (+S9)	150	113	183	148.7
PC (+S9)	239	174	181	198
G4
NC (-S9)	140	114	128	127.3
PC (-S9)	463	1340	463	755.3
NC (+S9)	116	96	158	123.3
PC (+S9)	108	154	262	174.7
G5
NC (-S9)	212	210	225	215.7
PC (-S9)	800	488	495	594.3
NC (+S9)	157	159	176	164
PC (+S9)	155	153	200	169.3
G6
NC (-S9)	103	139	139	127
PC (-S9)	344	330	331	335
NC (+S9)	188	180	179	182.3
PC (+S9)	104	190	197	163.7
G7
NC (-S9)	21	17	140	59.3
PC (-S9)	420	320	108	282.7
NC (+S9)	109	151	156	138.7
PC (+S9)	96	158	176	143.3
G8
NC (-S9)	80	87	51	72.7
PC (-S9)	802	720	832	784.7
NC (+S9)	238	253	261	250.7
PC (+S9)	350	387	189	308.7

Average of all eight groups	CFU(Average)
Water	121
DMSO	192
Mitomycin C (-S9)	547
2-Anthramine (+S9)	216

 

Ratio Matrix

Numerator Denominator	Water	DMSO	Mitomycin C (-S9)	2-Anthramine (+S9)
Water	1.0000	1.5868	4.5207	1.7769
DMSO	0.6302	1.0000	2.8490	1.1250
Mitomycin C (-S9)	0.2212	0.3510	1.0000	0.3949
2-Anthramine (+S9)	0.5601	0.8889	2.5324	1.0000

(2.0000>VALUE>1.5000)   (>2.0000)

Test Substance	Description
Water	To compare with other three substances, it is not a mutagen.
DMSO	To compare with water, its effect is just a little stronger, but not really a mutagen.
Mitomycin C(-S9)	To compare other three compounds, it is a really strong mutagen.
2-Anthramine	To compare with water, it is almost to be a mutagen, but its effect is just like DMSO. It is hard to decide that is cause by DMSO, 2-Anthramine or the metabolites of S9 from 2-Anthramine.