Tag: switch interval

Hello Today was our last day in the…

Amy Thompson / / Uncategorized

Hello!

Today was our last day in the lab! 🙁 We filmed our latest and final videoblog, removed the gel, stained and viewed it. We saw some separation from all but one of the plugs, however separation was very blurred. We decided to run the same samples again, but for longer and with a higher switch interval. We set up and ran a new gel for 18 hours, at 6V/cm, with a 1-30 second switch interval, a 1.4% gel with modified buffer flow.
Mike will remove the gel tomorrow, stain it and view for us. Hopefully we will see better separation, from the samples containing enough DNA.

The last 10 weeks have been amazing – i have learnt so much since i started and it’s going to be really odd to not be in the lab everyday. I have really enjoyed working through a project, having to work on problems and figure out solutions. Then getting to see the good and bad results. I am very impressed with myself, as i set out to blog everyday i was in the lab with what i have done, the good and the bad! and i have actually managed it! 🙂 I wasn’t sure about whether i would get on with videoblogging at the beginning, but i have really enjoyed filming them every week – although most the content was never included as we ALWAYS got distracted! I really hope those who have watched them have found them as interesting and enjoyable as we did.

It has been a very rewarding experience, and i am so grateful to everyone who has made the last 10 weeks, the best summer – you all know who you are! And of course Mike, who has put up with us and our random chatter, better than i ever imagined he would. It has been an absolute pleasure to work along side him, and i hope i get the chance to do it again.

Thank you all for reading 🙂

Hey All Removed plugs from SpeI enzyme buffer…

Amy Thompson / / Uncategorized

Hey All,

Removed plugs from SpeI enzyme, buffer and BSA, and washed in 1x wash buffer for 30mins. We removed this, then incubated them in 0.5x TAE buffer for an hour, while we prepared a 1.4% agarose gel. We then loaded 1/2 of each plug strain into individual wells, as well as the low range PFG marker, sealed with agarose and ran at 6V/cm, for 15 hours, with a 1-12 sec switch interval, and modified buffer flow.

Tomorrow, we will remove the gel, stain it and view it. We will also be filming our last videoblog! 🙁 as it will be the last day of our project – 10 weeks has gone by sooo fast! We may also be running another gel, depending on the results of the first. See you all then 🙂

Hey Everyone Today unfortunatly the 10 different strain…

Amy Thompson / / Uncategorized

Hey Everyone,

Today, unfortunatly the 10 different strain samples of propionibacterium acnes hadn’t grown enough to use yet, so we left them to grow longer all today and overnight.

We then removed the previously incubated old batch of plugs from SpeI enzyme, buffer and BSA. We incubated them all in 1 x wash buffer for 30mins at R.T. During that time we made up 1L of TAE 0.5x buffer, autoclaved it, allowed it to cool and used it to saturate the plugs for 1hr. We also used the buffer to make up a 1.4% gel, before cutting each of the 10 different strain propionibacterium acnes plugs from an old batch and placing them into wells. We also included a sample of the low range PFG marker. We then sealed the plugs using 1.4% agarose, we found a few problems whilst doing this. As we haven’t worked with as many plugs in the same gel at once before, one pipette tip (1ml) wasn’t enough to do all 11 wells. This was also made worst by how quickly the agarose cooled in the pipette creating bubbling and messy sealing. We plan to use a different tip for each sample next time, and work with slightly warmer agarose.

We then ran this gel for 18hrs, at 6V/cm, with 1-12 sec Switch interval. We also used the modified buffer flow method – which took a few times to balance effectively.

Tomorrow we will be hopefully starting plug production and viewing this latest gel. See you all then 🙂

Hey All Today i came in and filmed…

Amy Thompson / / Uncategorized

Hey All,

Today i came in and filmed my latest videoblog. I then removed the plugs from speI, buffer and BSA, and added 0.1x wash buffer for 30mins. While this was incubating, i autoclaved 1L of 0.5x TAE buffer, which i then used to incubate the plugs for an hour. I then prepared a 1.4% gel, with modified comb to create a large well. Once this had solidified i added one plug of the low range PFG marker, one whole plug of restriction enzyme treated plug in the large well, and finally one 1/3 of a restriction enzyme treated plug in one well. I then sealed the plugs, and ran the gel at 6v/cm for 15hrs, with 1-12sec switch interval ramping.

Mike will be in tomorrow to removed the gel, stain it and view. He will then save an image for me to observe with him on Monday 🙂 See you all then!

Hey All Didn’t come in till late today…

Amy Thompson / / Uncategorized

Hey All!

Didn’t come in till late today, to allow Propionbacterium acnes 6919 strain sample to grow, however the sample hadn’t grown enough, so we have left it to grow till tomorrow.

Meanwhile, i removed the plugs from speI, washed them in 1x wash buffer for 30 mins, then incubated them in TAE 0.5x until i had made and set a new gel. I used the modified comb as before to create an extra large well, so i could use 2 plugs in 1 well, as the plugs are from an old batch and therefore still contain minimal DNA.

I then ran the PFGE for 15hrs, at 6V/cm, with 1-12sec switch intervals. Mike also suggested using an increased amount of buffer in a large container below, and pumping buffer through the PFGE to replace buffer as it left the PFGE back into the container. This will hopefully keep all the buffer in the container as cold as possible, reducing smearing and making bands clearer.

Tomorrow, if the cells have grown enough, i can start to make new plugs, with our modifications.

Hello Everyone First day back in the lab…

Amy Thompson / / Uncategorized

Hello Everyone!

First day back in the lab! Me and Mike had a quick chat about what i wanted to do next and made a plan for this week, and possible plans for my final few weeks in the lab – it’s gone soo fast!
Mike re cultured the Propionbacterium acnes 6919 strain samples to allow them all of today and tomorrow morning to grow. Meanwhile, i treated my 3 remaining plugs with restriction enzyme – SpeI, which needs to incubate overnight. I also prepared and autoclaved 3L of 0.5X TAE buffer ready for running a gel with the restriction enzyme treated plugs and the low range PFG marker, using the settings we decided on last time i was in the lab – 6V/cm, 15hrs, 1-12sec Switch Intervals and a 1.4% gel.

Tomorrow will be a late start, to give Propionbacterium acnes 6919 strain samples as much time as possible to grow, before i begin making new plugs with our decided on modifications and setting up and running a new gel with the restriction enzyme treated plugs and new settings. Hopefully we will get some clearer and just as positive results! 🙂

Hello Today we removed our latest gel stained…

Amy Thompson / / Uncategorized

Hello,

Today we removed our latest gel, stained it and viewed it. Unfortunately we didn’t get very good results – there was alot of blurring on one the low range PFG marker samples, lack of clear band separation on the low range PFG marker samples and no expected band just below the wells for the non restriction enzyme plugs.

We decided that this was most likely due to lack of cell density, and therefore lack of DNA which that could be seen on the gel. We discussed that this could most likely to be fixed by allowing the Propionbacterium acnes samples to grow longer and therefore increase the cell density and DNA, and possibly by centrifuging more of the sample, to reach a higher conc. We also re researched info on cell density within plugs in the manual and journals – we found that the optimum OD was around 0.8-1.0 and we had been working with 0.24. Because of this increase in cell density/conc. we will also need to increase our lysozyme, mutanolysin and proteinase K to compensate.

Mike asked us to run a standard gel, in order to see if there was actually any DNA present at all. We ran a 0.8% gel, for 2 and half hours at 120V/cm with a 1kb ladder. We saw very faint separation, that did confirm that DNA was present, but at very low density/conc. as expected. This also confirmed our modifications which we will put into practise when i come from holiday on Monday 6th August.

After speaking to Mike we decided to attempt to run a new PFGE gel using the whole Propionbacterium acnes restriction treated plug, in one well, in order to use as much DNA as possible, and hopefully see some separation showing multiple bands due to lysis. We ran this 1% gel at 6V/cm, for 15hours with 1-12 sec switch interval ramping, using a whole Propionbacterium acnes restriction treated plug and the low range PFG marker.

Tomorrow we will be viewing this gel and filming our latest videoblog! 🙂

Afternoon Quite a quick day today came into…

Amy Thompson / / Uncategorized

Afternoon,

Quite a quick day today, came into the lab stained and viewed our gel. We saw little/no separation from the Propionibacterium acnes 6919 strain restriction enzyme plugs and the non restriction enzyme plugs. However we did see separation from the NEB yeast.

Myself and Jo decided that this may be due to our newest plugs. As mentioned before one of the pipettes we were using was full of liquid, and therefore may have given us incorrect amounts of substances when being used. We were unsure as to whether this was resulting in no separations from plugs on our latest gel, so we decided to run another gel with 2 samples of our old Propionibacterium acnes 6919 strain restriction enzyme plugs, and 2 samples of our new Propionibacterium acnes 6919 strain restriction enzyme plugs, along with one sample of new non restriction enzyme plug and 1 sample of NEB yeast.

We are hoping that by doing this we can establish if the lack of separation is due to our new plugs being poor, or the settings recommended by the new ladder – low range PFG marker, not being quite right. We set up the gel ad ran it with the same settings as yesterday – 15hrs, 6 V/cm, 1-12 second switch interval ramping, 1% agarose, and then a second block to hold the gel at 0.6 Vcm, 5 second switch interval until tomorrow morning when we will be in to remove it, stain it and view it.

Filming our newest videoblog tomorrow… 🙂

Hey Everyone Came into the lab this morning…

Amy Thompson / / Uncategorized

Hey Everyone,

Came into the lab this morning to start to set up our next gel. I made up 3 L of TAE 0.5X, incubated 1 Propionibacterium acnes 6919 strain restriction enzyme plug and 1 non restriction enzyme plug in 1X wash buffer and then in 0.5X TAE buffer. I then made up a 1% agarose gel and left it to set. I put the gel and plugs into the fridge and left them until 5pm.

When i came in at 5pm, i cut and loaded 2 samples of Propionibacterium acnes 6919 strain restriction enzyme plug, 1 sample of non restriction enzyme plug and 1 NEB yeast ladder. I sealed the plugs and then ran the gel according to the info recommended on the low range PFG marker ladder, for 15hrs, at 6 V/cm, with a ramped switch interval from 1-12 seconds. I added a second block as the gel is only running for 15hrs, and will finish at 8.30am tomorrow morning, of 0.6V/cm for 2hrs with a 5 second switch interval.

We will hopefully have the new ladder tomorrow, so we can modify our new gel according to the results we get when the run finishes tomorrow and use the new ladder!

See you all tomorrow 🙂

Hello Everyone Yesterday we ran a 24 hour…

Amy Thompson / / Uncategorized

Hello Everyone!

Yesterday we ran a 24 hour gel, at 4 V/cm with a 20 second switch interval PFGE gel. We used 3 large restriction enzyme treated plugs and a NEB ladder. Mike also asked us to research the genome for Propionibacterium acnes and the size of the fragments produced when lysed with SpeI. He asked us to do this so that we would be able to sketch a rough drawing of what we would really like to see on a perfect gel. Also to help us look for a more appropriate ladder to use with the Propionibacterium acnes samples, as the average size of a fragment is approx. 100kb, and the NEB yeast we are currently using runs from approx. 1900-225, not quite low enough to compare most fragments.

Today we observed the gel with Mike, which was how he expected it to look, with the NEB bands close together near the top of the gel. However, no bands were visible under the Propionibacterium acnes samples and Mike thinks we really need to have another go at making the plugs, perfecting the cell density and process. We also filmed our latest videoblog!

See you all on Monday 🙂

Hey All Today we came in removed stained…

Amy Thompson / / Uncategorized

Hey All,

Today we came in removed, stained and viewed our gel. The samples not treated with restriction enzyme showed a similar band, just underneath the wells. This was expected as the samples had not been treated and therefore lysed by the restriction enzymes, so separation according to size did not occur, producing only one/two bands. The samples treated with restriction enzyme showed some separation, but not enough, possibly due to not enough digestion. For both sample types it appeared that the largest plug size used worked the best. Mike also noted that this may be due to a lack of cell density within the plugs. The agarose gel also appeared very messy, and needed to be cleaned up. We destained the gel in TAE buffer, viewed it again and decided on the following modifications for our next PFGE run:

  • Run for 20 hours with a 20 second switch interval. The switch interval was decreased in order to produce better/clearer separation.
  • 3 large samples for each plug treated with restriction enzyme and those without, as the larger samples seemed to work the best.
  • We also deep cleaned our glass wear and autoclaved the buffer used within the sealing agarose, in order to try to clean up our gel as best as possible.
  • Finally, when we produce more plugs, we will try to increase the cell density within the plugs and modify our cell suspension buffer/centrifuge stage.
  • We are keeping the buffer, ladder, sealing in plugs, temperature and voltage the same.

Excited to see if our modifications produce clearer band separation 🙂

Afternoon Everyone Started off today by viewing our…

Amy Thompson / / Uncategorized

Afternoon Everyone!

Started off today by viewing our latest gel with Mike. Unfortunately our samples ran completely off the gel, and therefore we only saw the areas where the samples had passed. We also saw that the wells were very dark, due to too much DNA still being present within them. We also used the wrong ladder for Propionibacterium acnes. Mike therefore decided that we should run our next gel for 24 hours, at 4V/cm with a 30 second switch interval time, based on our two best previous gels (PFGE 5 and 6). We also decided to cut our plugs into different sizes in order to see how the size of the plug would effect the gel. We cut the plugs into two small pieces, one medium piece and one large piece. We still used samples of both plugs treated with restriction enzyme and without. We also used a reference ladder of NEB yeast.

We then helped Mike to re culture the Propionibacterium acnes by making up TGYE agar, autoclaving it and pouring 15 plates 20ml each. Which i have seen done before, but never done myself, so it was good to have the opportunity to practise! Managed to pour them all pretty well 🙂

We came in at 5pm, to cut off the first well of the Propionibacterium acnes sample treated with restriction enzyme, to see it’s progress. We removed it, stained it and viewed it. We will interpret it when we have the final gel tomorrow.

See you all tomorrow, when our next gel comes out at 11am 🙂

Evening Everyone Didn’t come into the lab till…

Amy Thompson / / Uncategorized

Evening Everyone!

Didn’t come into the lab till the afternoon today. Once we got in we removed the buffer from the plugs, and incubated them further in 1X wash buffer for 30 mins, at room temperature. While this was incubating myself and Jo made up 3L of 0.5X TAE buffer, melted agarose and then poured a new gel. The buffer was then removed and replaced with some of the 0.5X TAE buffer, that will be used to run the gel, to allow equilibration. We then cut and loaded 3 samples of fully treated Propionibacterium acnes DNA, 3 samples of Propionibacterium acnes DNA not treated with the restriction enzyme (SpeI) and 1 sample of lambda Hind III as a reference ladder.

Finally we sealed the plugs in with agarose and set the PFGE to run for: 12.7 hours at 6.0 V/cm with a ramping of 1-8 seconds, then 7 hours at 6.0 V/cm with a ramping of 0.1-2 seconds. We haven’t tried ramping before, but we decided to try this set up, as it is the method used in one of the journals we have been working from. Ramping is where one switch interval is used at the beginning of a time run, and another is used at the end, therefore over the time period the ramping slowly changes.

Tomorrow we will be filming our next videoblog, removing, staining and viewing our gel. As mike won’t be in, we will be discussing modifications and a plan for next week on Monday.

See you all tomorrow! 🙂

Hello Everyone Myself and Jo got into the…

Amy Thompson / / Uncategorized

Hello Everyone!

Myself and Jo got into the lab early this morning, in order to set up our next PFGE run with our new modifications. We made up 3L of 0.5X TAE buffer and 150ml of agarose (in order to reduce error), then left the gel to set. While it was setting we made up 50ml of agarose to seal the plugs into the wells. We then cut up 4 samples of NEB yeast, pushed them into the wells and sealed them up with agarose. We then set up the PFGE equipment to run at 6°C, for 15 hours at 6 V/cm with a 70 second switch interval and then for 11 hours at 6 V/cm with a 120 second switch interval.

The run is to finish at 12.15pm tomorrow, so myself and jo will be in the lab from 11am to film our second videoblog section! 🙂

See you all tomorrow morning!

Evening all Myself and Jo spent this morning…

Amy Thompson / / Uncategorized

Evening all!

Myself and Jo spent this morning researching the next stages of our project, then we came into the lab for 3pm, in order to take our gel out of the PFGE. We then stained it up and viewed it with Mike. We saw much better separation than before, with the bands reaching all the way to the bottom of the gel, and running off. Both yeast samples, BioRad and NEB, also appeared consistent with each other. The 1Kb ladder was not visible, which was expected. However, the separations slightly shifted to the right, producing wonky bands, that unfortunately weren’t very defined. Mike said this was most likely due to imperfections in the agarose, and we could rectify this by producing 150ml of agarose in order to reduce error. In order to try and stop the yeast sample running off the gel we decided to change our switch interval as well. We also decided that as the NEB yeast has been the most consistent and successful sample, we would stop running the BioRad yeast and 1Kb ladder. We will keep the size of the plugs the same, and well as sealing them with agarose.

Reviewing the NEB yeast information we decided to try running our next gel following the guidelines provided, 1% agarose, 15 hours at 6 V/cm with a 70 second switch interval and then 11 hours at 6 V/cm with a 120 second switch interval. Using 0.5X TAE buffer, 2 samples of NEB yeast and at 6°C as before.

See you all tomorrow morning as we set up our next, and possible last gel before starting on our next stage in the project! 🙂

Afternoon Everyone Myself and Jo came in at…

Amy Thompson / / Uncategorized

Afternoon Everyone!

Myself and Jo came in at 9am this morning, and began filling out our COSHH and risk assessment forms. Although they were a bit of a challenge we managed to get them finished before our PFGE gel came out at 11.30am. Filling out the COSHH form involved making a list of all the chemicals we have used so far within our project, looking up their hazard category (using MDSS – which was very useful!), assessing their exposure potential (glacial acetic acid and ethidium bromide being our highest), steps we could take to protect ourselves (containment level), first aid and how to dispose of them. Our containment level for procedure was 1. The Risk assessment form involved identifying possible hazards within the lab, reviewing control measures we could take to reduce this risk and giving an overall risk assessment rating, ours was medium. I felt that filling out these forms was good practise as next year, during our final year projects, we will be required to do this ourselves for our own projects.

We also watched Mike re culture the Propionibacterium acnes in the anaerobic cabinet, which was really interesting to see!

We then removed, stained and viewed our gel. We managed to obtain much clearer bands and we no longer had very dark areas (large amounts of DNA) within the wells. However we did notice slight band elongation, which is caused by increased temperature. This is expected, as unfortunately the PFGE is still running at 25/26°C, instead of the 14°C it really should be running at.

We therefore decided to keep the smaller amount of DNA we were putting in the wells, keep sealing in the plugs, keep the buffer at 0.5X and not include the initial switch interval as before. In order to reduce the temperature and obtain clearer bands we decided to move the PFGE equipment into the fridge (to run at 6°C). In order to obtain more separation we decided to increase the voltage to 6.0 V/cm. We therefore set up and started a new run with these changes for 24 hours at 6.0 V/cm and with a 45 second switch interval, still using 2 samples of NEB yeast, 2 samples of BioRad yeast and 2 samples of 1Kb ladder. With a second block for 2 hours at 0.6 V/cm and with a 45 second switch interval, in case we weren’t ready to remove the gel.

Really excited to see how the massive change in temperature effects our separations! 🙂

See you all tomorrow!

Afternoon All Quite a quick day today Myself…

Amy Thompson / / Uncategorized

Afternoon All,

Quite a quick day today! Myself and Mike viewed the PFGE gel we ran last Thursday to Friday. Although the run appeared better in terms of visible band separations, the bands were still fairly faint and the wells appeared very dark. Mike said that this was due to too much DNA being left in the wells, we therefore decided to reduce the amount of plug we put into the well, by cutting the plugs as small as we could. We decided to reduce the buffer %, from 1% to 0.5%, to get rid of the initial 3 hour with 15 second switch time at 2.0 V/cm and add a second band marker (1Kb ladder). This 1Kb ladder was added as a reference in order to help us work out how many bases were present within samples.

We set up a PFGE run with all these new changes for 24 hours at 2.0 V/cm with a 45 second switch interval, and a second block for 1 hour at 0.6 V/cm with a 45 second switch interval in case we weren’t ready tomorrow morning to remove the gel. So we will see tomorrow what our changes have done! 🙂

Mike also showed me the TGYE agar he was making up, in order to re culture the Propionibacterium acnes samples. He showed me how to make up the agar, autoclave it and pour it. Tomorrow he is going to show me how to streak plate the Propionibacterium acnes samples onto the TGYE agar plates in the anaerobic cabinet. I have never used it before, so it should be really good to see!

See you all tomorrow! 🙂