Team:Lethbridge CCS/Notebook/October

From 2008.igem.org

(Difference between revisions)

Revision as of 20:11, 18 October 2008

For earlier work, see September Notebook.

met to discuss why we had not obtained green colonies from our transformation as expected. There was definitely cutting happening from the EcoRV digest, but the bands showed up at the wrong size. Final conclusion was that probably nothing had worked right from step 1! Most likely what we thought was pSB1A7 actually wasn't, a conclusion we came to based on our own funny results, and on some of the results obtained by the U of L team. So we've probably just been seeing the original template plasmid in all our follow up gels, etc. Decided to start again, this time using pSB1A2 (though it doesn't have the double terminators we would actually like to see), as the U of L team has it and knows it works. So new primers were designed for this, as well as for xylE, a gene the ULeth team is using, which we hope to use to see whether we can really build a 'new' BioBrick using our method.

6 Oct 2008

(Peter, Elizabeth, Glenda, Nathan)

Reviewed Saturday's discussion; checked that primers were correct and sent off order; discussed our logo and ordering of T-shirts; reviewed steps we would have to go through once our new primers arrive

11 Oct 2008

(Peter, Elizabeth, Marc, Glenda)

Roxanne had already resuspended and diluted our primers (psB1A2 forward and reverse; LIC_xylE forward and reverse) [100 μM stock; 10μM working].
Set up and ran PCRs on pSB1A2 and LIC_xylE
- for each, we did 1 x, 1/10 x and 1/100 x of our template and a range of annealing temperatures (54°C, 58°C, 62°C for pSB1A2; 48°C, 52°C, 56°C for LIC_xylE), giving nine variations for each PCR;
- used materials and amounts as per Phusion polymerase kit

- Cycling temperatures and times for PCR
    Initial denaturation           98°C                 30 sec    ___
    Denaturation                   98°C                 10 sec       |
    Annealing                      gradient as above    30 sec        |--- 30 cycles
    Extension                      72°C                  1 min    ___|
    Final extension                72°C                 10 min
    Hold                           4°C                  hold

numbering:

            54°C      58°C      62°C
      1x      1         4         7
   1/10x      2         5         8
  1/100x      3         6         9

ran a 1% agarose gel on pSB1A2 - expected size ~2000 bp. No results. After discussion, we think this may be due to putting in only enough polymerase for one reaction, not 10.

[lanes: 1kb ladder, 1-5, 1kb ladder, 6-9, blank, 1kb ladder]

ran a 1% agarose gel on xylE (LIC) - expected size ~1000bp.

[lanes: 1kb ladder, 1-5, 1kb ladder, 6-9, blank, 1kb ladder]

13 Oct 2008

(Peter, Marc - yes, we were in the lab on Thanksgiving!)

Re-did PCR of pSB1A2, this time using GFP complete (1) plasmid-prepped by Roxanne.

[Lanes: 1kb ladder, 1-9, blank, 1kb ladder]

Seems to have worked. Possible problem: circular pSB1A2 with GFP complete (~3000bp) may run at the same place as linear pSB1A2 alone (~2000bp). Will run another gel tomorrow to check.

14 Oct 2008

(Marc)

Ran 1% agarose gel to check where pSB1A2 with GFP complete (template for our pSB1A2 PCR) runs on a gel.

[Lanes: 1kb ladder, GFP complete (1), #2, #5, #8, 1kb ladder]

Unfortunately, template (circular) runs at the same place as our PCR product. We could possibly digest the BioBrick plasmid first; then at least there wouldn't be any competition for transformation.

(Elizabeth, Peter, Glenda)

Used Fermentas Rapid Ligation kit on our around the world PCR products(1/10, 1/100 concentration, 54°)

-1 μL PCR product
 2 μL 5x buffer              incubated for 1 hour at room temperature
 1 μL ligase
 6 μL Water

Did a transformation of ligated DNA into highly competent cells (using 1 μL ligation mix (1/10, 1/100, pUC19 control)
- left on ice for 30 min
- heat-shock for 30 sec at 42 degrees
- ice for 2 minutes
- add 900 μL SOC medium, 1 hour in shaker at 37 degrees
- plated concentrated and dilute of each of above dilutions
- incubated overnight

At the U of L iGEM meeting, we discussed our concern about template running at same place as PCR product. HJ recommended doing a DpnI digest since this would cleave the template but leave our PCR product intact. We could then run a gel to compare sizes.

15 Oct 2008

(Glenda, Elizabeth, Peter)

Interestingly enough, where we had expected to see all or almost all green colonies (if template was present as expected), but in fact there were only white colonies
Grew up colonies (2 each from our 1/10 and 1/100 dilute plates)
- 5 μL ampicillin, add with colonies to culture
- Incubate at 37°C for 12 hours

Set up DpnI digestion

 15 μL PCR product/template (used 1x LIC_GFP) 
 1.75 μL 10x Tango buffer 
 1 μL DpnI

Incubated 1 hour at 37°C and then ran a gel

  Lane 1: 1 kb GeneRuler ladder
  Lane 2: GFP with DpnI 
  Lane 3: GFP without DpnI 
  Lane 4: LIC_GFP with DpnI 
  Lane 5: LIC_GFP without DpnI 
  Lane 6: 1 kb GeneRuler ladder

gel looked a little strange (not well-defined), but seems to verify that our early amplification worked; Lane 2 had marks at a variety of lengths, indicating cutting of GFP with DPN, while the other lanes all looked very similar,with only one length, indicating there was very little template left in our LIC_GFP. The only slightly puzzling thing was the length of the DNA it seemed to show (shorter than expected)

16 Oct 2008

(Elizabeth, Marc)

Performed miniprep of pSB1A2_LIC from 'LIC_GFP' cultures, as per QIAprep Spin Kit.
- Notes: did not do optional PB buffer step; pellet of 1/100 #2 was very thin and elongated.

Prepared glycerol stocks of all four cultures. Stored in HJ's -80°C

Quantified resulting plasmid concentrations using UV/vis spectrophotometer at 1:25 dilution.

Sample      Concentration (ng/μL)      260/280nm absorbance ratio
1/100 #1               88                      1.95
1/100 #2               50                      1.90
 1/10 #1               57                      1.83
 1/10 #2               81                      1.83

Ran 1% agarose gel to check size of purified plasmid (100V, 25min)

[Lanes: 1/25 dilution of 1/10 #1, 1kb ladder (punctured well?), 1/10 #1, 1/10 #2, 1/100 #1, 1/100 #2, 1kb ladder, 1/25 dilution of 1/10 #2]

17 Oct 2008