Questions relating to protocols, procedures, and good practice when using laboratory equipment.

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6
votes
2answers
943 views

How long can I store autoclaved disposables and reagents?

I want to stock up on autoclaved disposables, such as Eppendorf tubes, pasteur pipettes etc., and some buffers. If I don't open the container after autoclaving, how long can I store autoclaved ...
0
votes
1answer
720 views

DNA gel extraction: chemical contaminants

I am performing a gel extraction to purify DNA after a double digest with EcoRI and BamHI. After the gel extraction I need to complete a ligation step before bacterial transformation. The problem I ...
4
votes
1answer
2k views

What is immunopanning (vs. immunoprecipitation and FACS)?

I had never heard the term before today. From what I can tell, it's using antibodies to purify a cell population of interest. I would appreciate more details, especially in how it differs from ...
2
votes
3answers
1k views

Improving Gel Extraction yields

How can I improve my Gel Extraction yields. We use the standard protocol from Qiagen, gel extraction, dissolve in QG buffer at 42C and purify via anion exchange columns. However, with 500 ng we ...
4
votes
1answer
223 views

What is a simple protocol for staining cells in suspension?

I am an engineering student studying how electric fields affect cells, specifically the phenomena of electroporation in living cells. I know that electroporation is widely used for introducing genes ...
2
votes
1answer
147 views

What's the difference between a free chromosome fragment and an extrachromosomal array?

This is reference to a review on C. elegans mosaic analysis by Yochem and Herman, in which the authors make a distinction between free chromosome fragments and extrachromosomal arrays. For the ...
4
votes
0answers
61 views

Does preservation in ethanol alter leaf litter mass?

I have benthic samples that were collected with an Ekman dredge from some small ponds. The samples contain quite a bit of coarse particulate organic matter (CPOM, basically dead leaves). I would ...
2
votes
0answers
154 views

Resuspending Cells from a filter plate

My experiment involves pulling down cells on to a filter plate for a variety of assays. However, I want to ensure that my cells are alive so I am trying to resuspend them so that I can do an accurate ...
4
votes
1answer
243 views

Is DNA green viewer carcinogenic?

I use DNA green viewer in Lab to see DNA and RNA bands. Some peers told me it is carcinogenic and is not safe. Is this correct? If yes, are there better choices to use in working with gel?
7
votes
1answer
442 views

Can I image Coomassie and GFP in gels at the same time with a fluorescence scanner?

I'm working with a GFP-tagged protein and am routinely using a fluorescence imager (GE Typhoon) and a standard optical scanner to capture fluorescent and absorption images, respectively, of my ...
5
votes
1answer
434 views

What are good practices with reusing desalting columns

At least according to a few sources Prozyme and Protocols-Online, it is possible to reuse desalting columns and since I'm cheap I would like to also. Key things seem to be washing with several column ...
9
votes
2answers
5k views

Why should I degas my gel solution for polyacrylamide gels?

In protocols for polyacrylamide gel electrophoresis (PAGE) I often see instructions to degas the gel solution by putting it under vacuum for 10-15 minutes before polymerizing the gel. I usually ...
13
votes
2answers
3k views

What effect does vortexing have on a fluid sample that simple mechanical shaking does not?

Some protocols call for fluid samples to be mixed with a "vortexer" on the high setting. What effect does the vortexing have on fluid samples that mechanical shaking does not? Does it shear long ...
8
votes
2answers
153 views

What type of CCD system is required to take photos of luciferase

I'm working with luciferase and I want to be able to take a photo of it. The trouble is, I can see the luciferase glowing in all of its glory in front of me but no matter how hard I try, I can't take ...
9
votes
2answers
3k views

How do I clean and calibrate pipettes, and how often should I do it?

I work in a lab where all the pipettes are shared. We often have visiting students who come and use the pipettes for a short project. So when I work with them, they might have been handled by other ...