ladders – SB209

Afternoon Everyone,

Today we started the looong washing phase of plug making! We washed all 24 plugs (2 per sample, and 4 per 6919 strain sample) as before, 4 times for an hour each in 1X wash buffer. We then separated off plugs from samples 2-11, added fresh 1X wash buffer and put them into the fridge for storage. We then washed the 4 6919 strain sample plugs with 0.1X wash buffer twice, and separated off 1 plug (not to be treated with restriction enzyme Spe1). We then added 1X Spe1 buffer to incubate the plugs, before removing this and adding fresh 1X Spe1 buffer, Spe1 enzyme and BSA. We then left the 3 plugs to incubate overnight at 37ºC.

While waiting for washes, we used online REviewer software to work out the number and size of fragments Spe1 will produce – 85 fragments ranging from 132702bp – 817bp, with the most fragments approx. 10000bp (100kb). We therefore decided to order BioLabs (NEB) low range PFG marker that ranges from 194000bp-2030bp (194-2.03kb), that will cover all the larger-medium size fragments only missing 4 smallest fragments. The image produced by REviewer is attached, showing all fragments along genome

Tomorrow, we will be setting up our next gel, using settings recommended by BioLabs (NEB) on the new ladder we have chosen to use. Hopefully we will have the new ladder very soon, so we can run it!

See you all tomorrow!

Evening All,

Today myself and Jo started our second batch of plugs, made from 10 different Propionibacterium acnes patient samples and a Propionibacterium acnes 6919 strain. We followed the same protocol as before, but made 4 plugs from the Propionibacterium acnes 6919 strain and 2 plugs from each of the 10 different Propionibacterium acnes patient samples. Mike checked their OD to ensure appropriate cell density (0.25). We also centrifuged down 2 eppendorf tubes containing 1ml of the same sample to pellet, we then eluted the pellet in 200ul of suspension buffer each, in order to produce a cell concentration of 2 x 10^8 ,we then removed 100ul.

Having agarose divided into separate eppendorfs was very useful when melting agarose to combine with the centrifuged samples.
However we did experience a few problems, when trying to pipette the agarose and centrifuged sample into the molds some bubbles formed, and some samples appeared to contain less then others resulting in some plugs being half the size of others. We decided that this was most likely due to one of our pipettes being inaccurate due to liquid internally, and that we only produced exactly how much we needed, resulting in some being lost during the procedure. In order to correct this Mike took apart and emptied the pipette for us, and we planned to modify the method to produce slightly more (10%) to allow for losses.

After the plugs had set, we separated them all into separate eppendorf tubes, added lysozyme and buffer, mutanolysin and incubated for 3 hrs at 37ºC. We then added proteinase K and buffer and left overnight to incubate.

We also discussed more appropriate ladders with Mike, he showed us afew that might be better to use, such as http://www.neb.uk.com/productcatalogue/productinfotransfer.aspx?id=/New%20England%20Biolabs/Markers%20and%20Ladders/PFG%20Markers/N0340.
We decided that tomorrow during plug washing, we would use the online genome cutting software we have used before to find exactly how many and what size fragments Spe1 would produce when lysing Propionibacterium acnes so we could make a final decision on ladder size range, and order one asap.

See you all tomorrow! 🙂

Tag: ladders

Afternoon Everyone Today we started the looong washing…

Evening All Today myself and Jo started our…