Alexandra Johnson

6 Questions 316 Answers 0 Followers

Questions related from Alexandra Johnson

Can plasmids substantially bigger than the SV40 genome be effectively replicated using an SV40 origin of replication?

I want to amplify the gene dosage on a large plasmid (~30 kb) in HEK293T cells by cloning a Simian Virus 40 origin of replication into it, but I've been having trouble finding if it's possible for...

12 August 2025 3,615 2 View

Less viscous microscopy mounting media for immunofluorescence?

I am trying to perform immunohistochemistry on cells which are growing in different wells of this kind of slide: https://www.fishersci.com/shop/products/hydrophobic-prntd-slide-8-well/5029205...

01 April 2025 8,984 2 View

What's the purpose of n,n-dimethylformamide (DMF) in tagmentation reactions?

Almost every Tagmentation library prep protocol has a reaction buffer which contains a high concentration of DMF but I can't find a reason why it's included in the reaction buffer for the Tn5...

23 September 2024 5,483 2 View

Is it possible to elute a 14x his tagged protein off of a cobalt column with imidazole?

I have a construct that goes (N to C terminus) 14x His tag - SUMOstar cleavage tag - Protein of Interest (POI). The initial idea was to elute using on-column cleavage of fusion protein, but this...

23 June 2021 4,770 10 View

Does cleaning up cDNA after reverse transcription reduce late cycle background?

I've been wondering if removing the random primers from the reverse transcription reaction either with a column or precipitation before using it as a qPCR template reduces the background a bit in...

26 December 2020 6,549 4 View

Anyone know why high concentrations of glycine/threonine weaken cell walls in gram positive bacteria?

I noticed that a lot of transformation protocols for gram positive bacteria (especially lactic acid bacteria) call for high concentrations of glycine and/or threonine as a "cell wall weakening...

19 June 2017 1,940 1 View