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Revision as of 03:18, 16 September 2016
Laboratory Notes
☞☟ Week1 (May 16–May 22)
In order to make sure our "consumer" efficient, we should first knock out the luxS gene in our engineering bacteria GR286(a simplified strain of Bacillus amyloliquefaciens LL3). We used a markerless gene replacement method to knock out the luxS gene.
Construction of targeting vector : the upstream and downstream of luxS gene were combined by over-lapping PCR and ligated into plasmid pKSU.
Transformed pKSU-ΔluxS into GR286, and selected out positive clones.
2× Taq Master Mix | 10μL |
pKSU-F | 1μL |
pKSU-R | 1μL |
Bacterium solution | 1μL |
ddH2O | 7μL |
Total | 20μL |
94℃ | 10 min | |
94℃ | 30 sec | |
58℃ | 30 sec | 30 cycles |
72℃ | 1 min 30 sec | |
72℃ | 10 min | |
16℃ | ∞ |
The transformants were cultured at 42℃ with chloramphenicol to select single-crossover clones.
2× Taq Master Mix | 10μL |
luxS-up-F | 1μL |
luxS-dn-R | 1μL |
Bacterium solution | 1μL |
ddH2O | 7μL |
Total | 20μL |
94℃ | 10 min | |
94℃ | 30 sec | |
56℃ | 30 sec | 30 cycles |
72℃ | 2 min | |
72℃ | 10 min | |
16℃ | ∞ |
☞☟ Week2 (May 23–May 29)
The single-crossover strains were then cultured at LB medium and passaged every 12 hours for 4 generation.
Cultured the last generation at medium with 5-fluorouracil to select double-crossover clones. Regretfully, we didn't get the double-crossover clones.
2× Taq Master Mix | 10μL |
luxS-up-F | 1μL |
luxS-dn-R | 1μL |
Bacterium solution | 1μL |
ddH2O | 7μL |
Total | 20μL |
94℃ | 10 min | |
94℃ | 30 sec | |
56℃ | 30 sec | 30 cycles |
72℃ | 2 min | |
72℃ | 10 min | |
16℃ | ∞ |
☞☟ Week3 (May 30–Jun 05)
We cultured transformants at 42℃ with chloramphenicol again and selected the single-crossover clones successfully.
2× Taq Master Mix | 10μL |
luxS-up-F | 1μL |
luxS-dn-R | 1μL |
Bacterium solution | 1μL |
ddH2O | 7μL |
Total | 20μL |
94℃ | 10 min | |
94℃ | 30 sec | |
56℃ | 30 sec | 30 cycles |
72℃ | 2 min | |
72℃ | 10 min | |
16℃ | ∞ |
The single-crossover strains were then cultured at LB medium and passaged every 12 hours for 4 generations.
Cultured the last generation at medium with 5-fluorouracil to select double-crossover clones. We finally got our aimed strain—GR286ΔluxS.
2× Taq Master Mix | 10μL |
luxS-up-F | 1μL |
luxS-dn-R | 1μL |
Bacterium solution | 1μL |
ddH2O | 7μL |
Total | 20μL |
94℃ | 10 min | |
94℃ | 30 sec | |
56℃ | 30 sec | 30 cycles |
72℃ | 2 min | |
72℃ | 10 min | |
16℃ | ∞ |
☞☟ Week4 (Jun 06–Jun 12)
Cultured the GR286ΔluxS strain and made it competence for future use.
Cloned the lsrACDB gene from Bacillus thuringiensis and ligated it to T-vector.
2× Taq Master Mix | 25μL |
lsrACDB-F | 2μL |
lsrACDB-R | 2μL |
Bacterium solution | 2μL |
ddH2O | 19μL |
Total | 50μL |
94℃ | 10 min | |
94℃ | 30 sec | |
57℃ | 30 sec | 30 cycles |
72℃ | 4 min 30 sec | |
72℃ | 10 min | |
16℃ | ∞ |
10× DNA Ligase Buffer | 2μL |
T4 DNA Ligase | 1μL |
pMD19 T-Simple Vector | 1μL |
lsrACDB | 3μL |
ddH2O | 13μL |
Total | 20μL |
Reaction condition: 16℃ overnight |
Transformed the T-lsrACDB into DH5α and coated plate, and then selected positive clones by colony PCR.
2× Taq Master Mix | 10μL |
M13F | 1μL |
M13R | 1μL |
Bacterium solution | 1μL |
ddH2O | 7μL |
Total | 20μL |
94℃ | 10 min | |
94℃ | 30 sec | |
59℃ | 30 sec | 30 cycles |
72℃ | 4 min 30 sec | |
72℃ | 10 min | |
16℃ | ∞ |
After restriction enzyme digestion verification, we sent them to sequencing. Unfortunately, the sequencing result showed some mutations in cloning gene.
10× FastDigest Buffer | 2μL |
BamH Ⅰ | 1μL |
T-lsrACDB | 1μL |
ddH2O | 7μL |
Total | 20μL |
Reaction condition: 37℃ for 40 min |
We repeated the process of gene cloning but there were still some mutations.
We finally decided to request the gene company to synthesize the lsrACDB gene.
☞☟ Week5 (Jun 13–Jun 19)
This week, we started to construct another controller―supplier.
We cloned a strong promoter C2 from former kit and cloned luxS gene from GR286.
2× Taq Master Mix | 25μL |
C2-F | 2μL |
C2-R | 2μL |
p-C2 | 2μL |
ddH2O | 19μL |
Total | 50μL |
94℃ | 10 min | |
94℃ | 30 sec | |
58℃ | 15 sec | 30 cycles |
72℃ | 30 sec | |
72℃ | 10 min | |
16℃ | ∞ |
2× Taq Master Mix | 25μL |
luxS-F | 2μL |
luxS-R | 2μL |
Bacterium solution | 1μL |
GR286 | 2μL |
ddH2O | 19μL |
Total | 50μL |
94℃ | 10 min | |
94℃ | 30 sec | |
59℃ | 30 sec | 30 cycles |
72℃ | 30 sec | |
72℃ | 10 min | |
16℃ | ∞ |
Fuse the two segments together by fusion PCR, and ligated it into T-vector. Then, transformed the vector into DH5α.
2× Taq Master Mix | 25μL |
C2-F | 2μL |
luxS-R | 2μL |
C2 | 2μL |
luxS | 2μL |
ddH2O | 17μL |
Total | 50μL |
94℃ | 10 min | |
94℃ | 30 sec | |
59℃ | 30 sec | 30 cycles |
72℃ | 40 sec | |
72℃ | 10 min | |
16℃ | ∞ |
10× DNA Ligase Buffer | 2μL |
T4 DNA Ligase | 1μL |
pMD19 T-Simple Vector | 1μL |
C2-luxS | 4μL |
ddH2O | 12μL |
Total | 20μL |
Reaction condition: 16℃ overnight |
Selected the positive clones by colony PCR.
2× Taq Master Mix | 10μL |
M13-F | 1μL |
M13-R | 1μL |
Bacterium solution | 1μL |
ddH2O | 7μL |
Total | 20μL |
94℃ | 10 min | |
94℃ | 30 sec | |
59℃ | 30 sec | 30 cycles |
72℃ | 40 sec | |
72℃ | 10 min | |
16℃ | ∞ |
We chose 4 positive strains to culture overnight and extracted the plasmid. After restriction enzyme digestion verification, we sent them to sequencing.
10× FastDigest Buffer | 2μL |
BamH Ⅰ | 1μL |
T-lsrACDB | 1μL |
ddH2O | 7μL |
Total | 20μL |
Reaction condition: 37℃ for 40 min |
☞☟ Week6 (Jun 20–Jun 26)
The sequencing result showed there's a correct strain. So we can use the strain for the following experiment. We obtained the correct plasmid T-C2-luxS from DH5α. Then we got the fragment C2-luxS by digestion and gel extraction.
10× FastDigest Buffer | 4μL |
BamH Ⅰ | 2μL |
T-C2-luxS | 25μL |
ddH2O | 9μL |
Total | 20μL |
Reaction condition: 37℃ for 40 min |
Ligated the C2-luxS to linearized plasmid pWH1520, and transformed it into DH5α.
10× DNA Ligase Buffer | 2μL |
T4 DNA Ligase | 1μL |
pMD19 T-Simple Vector | 1μL |
C2-luxS | 5μL |
ddH2O | 11μL |
Total | 20μL |
Reaction condition: 16℃ overnight |
Extracted the plasmid pWH-C2-luxS from DH5α. To prevent the plasmid from DAM&DCM methylation, we transformed it into E.coli JM110.
Extracted the plasmid pWH-C2-luxS from JM110,and dealt with it by BamH Ⅰ methylase.
10× BamH Ⅰ methyltransferase Buffer | 10μL |
BamH Ⅰ methyltransferase | 1μL |
S-adenosylmethionine | 0.5μL |
pWH-C2-luxS | 80μL |
ddH2O | 8.5μL |
Total | 100μL |
Reaction condition: 37℃ for 1 hour |
Transformed the plasmid into GR286 by electroporation.[Failed]
☞☟ Week7 (Jun 27–Jul 03)
This week, we tried to use different voltages to transform the plasmid. Sadly, all of these tries got bad results.
We considered whether the luxS gene is a little toxic for GR286, and the bacteria tends to refuse the gene when we added a strong promoter in front of it. So, we planned to use induced expression to reconstruction our expression vector.
The plasmid pWH1520 contains the strong xylA promoter originating, and transcription from this promoter is xylose inducible. So, the gene of interest carries its own ribosome binding sequence (RBS) and translation initiation codon. Based on these points, we redesigned primers.
☞☟ Week8 (Jul 04–Jul 10)
We cloned luxS gene from GR286 using our new primers.
2× Taq Master Mix | 25μL |
YD-luxS-F | 2μL |
YD-luxS-R | 2μL |
Bacterium solution | 2μL |
ddH2O | 19μL |
Total | 50μL |
94℃ | 10 min | |
94℃ | 30 sec | |
58℃ | 30 sec | 30 cycles |
72℃ | 40 sec | |
72℃ | 10 min | |
16℃ | ∞ |
Purified the luxS fragment by gel extraction, and ligated it into linearized pWH1520. Then, transformed the vector into DH5α.
10× FastDigest Buffer | 4μL |
BamH Ⅰ | 2μL |
pWH1520 | 25μL |
ddH2O | 9μL |
Total | 40μL |
Reaction condition: 37℃ for 40 min |
10× DNA Ligase Buffer | 2μL |
T4 DNA Ligase | 1μL |
linearized pWH1520 | 1μL |
luxS | 3μL |
ddH2O | 13μL |
Total | 20μL |
Reaction condition: 16℃ overnight |
Selected the positive clones by colony PCR.
2× Taq Master Mix | 10μL |
pWH-F | 1μL |
pWH-R | 1μL |
Bacterium solution | 1μL |
ddH2O | 7μL |
Total | 20μL |
94℃ | 10 min | |
94℃ | 30 sec | |
58℃ | 30 sec | 30 cycles |
72℃ | 40 sec | |
72℃ | 10 min | |
16℃ | ∞ |
We chose 4 positive strains to culture overnight and extracted the plasmid. After restriction enzyme digestion verification, we sent them to sequencing.
10× FastDigest Buffer | 2μL |
BamH Ⅰ | 1μL |
pWH-luxs | 10μL |
ddH2O | 7μL |
Total | 20μL |
Reaction condition: 37℃ for 40 min |
☞☟ Week9 (Jul 11–Jul 17)
The sequencing result showed there's three correct strains. So we can choose a correct strain for the following experiment. We extracted the correct plasmid pWH-luxS from DH5α. To prevent the plasmid from DAM&DCM methylation, we transformed it into E.coli JM110.
Extracted the plasmid pWH -luxS from JM110,and dealt with it by BamH Ⅰ methylase.
10× BamH Ⅰ methyltransferase Buffer | 10μL |
BamH Ⅰ methyltransferase | 1μL |
S-adenosylmethionine | 0.5μL |
pWH-C2-luxS | 80μL |
ddH2O | 8.5μL |
Total | 100μL |
Reaction condition: 37℃ for 1 hour |
Transformed the plasmid into GR286 by electroporation, and selected positive clones.
The construction of supplier was complished!
☞☟ Week10 (Jul 18–Jul 24)
Our synthetic lsrACDB gene came back. We first used restriction-ligation method to ligate lsrACDB to plasmid pWH1520, but we failed to select positive after several tries.
10× DNA Ligase Buffer | 2μL |
T4 DNA Ligase | 1μL |
linearized pWH1520 | 1μL |
lsrACDB | 3μL |
ddH2O | 13μL |
Total | 20μL |
Reaction condition: 16℃ overnight |
Considering the lsrACDB gene is a large fragment (4500bp), we used ClonExpress technique cloning the gene again to improve the efficiency of ligation. We divided the lsrACDB sequence into two parts and cloned them separately. Then we ligated the two segments to the plasmid pWH1520 and transformed it into DH5α. After that, we used PCR to select the positive clones. However, we didn't get a good result.
☞☟ Week11 (Jul 25–Jul 31)
We learnt a new method called circular polymerase extension cloning (CPEC) for high-throughput cloning of complex and combinatorial DNA libraries, and we decided to use this method to try ligating our lsrACDB gene. It's encouraging that we succeeded to ligate the lsrACDB gene to the plasmid pHT-01.
☞☟ Week12 (Aug 1–Aug 7)
Since we have constructed "supplier" and part of "consumer", we decided to measure the growth curve to explore the function of our "controller".
GR286 | wild strain as control group |
GR286ΔluxS | GR286 without luxS gene |
pWH-luxS | luxS overexpression plasmid in GR286; without induced by xylose |
pWH-luxS + xyl | luxS overexpression plasmid in GR286; induced by xylose |
pWH1520 | empty plasmid in GR286 as control group |
pHT-lsrACDB | lsrACDB overexpression plasmid in GR286ΔluxS |
pHT-01 | empty plasmid in GR286ΔluxS as control group |
Cultured media of our supplier was tested for the presence of AI-2 by inducing luminescence in Vibrio harveyi reporter strain BB170.
☞☟ Week13 (Aug 8–Aug 14)
For our consumer, we should also clone the lsrK and lsrFG gene for phosphorylating and degrading AI-2. We used ClonExpress technique cloning the two genes and ligated them to plasmid pHT-01 successfully.
We cocultured the supplier with BB170 and tested the fluoresent intensity to explore the function of supplier. (negative result)
☞☟ Week14 (Aug 15–Aug 21)