11
votes
Bacterial cells disappearing from culture with time
That sounds like phage. The pattern of initial growth followed by catastrophic death with some cell debris is classic for induction and lysis.
Have you observed anything strange on plates? You could ...
- 186
8
votes
A biological system to measure time
There are lots of biological clocks, or clocks made of biological components. The circadian clock is an important, though complicated, example. There are excellent engineered clocks that form some of ...
7
votes
Accepted
Why is glycerol supplied/used as 87% solution?
Typically, a glycerol stock will have a final concentration of 10-20% of glycerol. Glycerol is highly viscous. Pipetting higher concentrations of glycerol is difficult (especially for smaller volumes)....
- 35.6k
7
votes
Is it safe to work with HeLa cells?
Most guidelines for HeLa (and most cells of human origin) say they should be kept at a BSL2 level. For example, from a 2007 publication in Applied Biosafety:
Work with cell cultures from human or ...
- 14.3k
6
votes
Tumour cell injection into a mice
You should not be asking random people on the internet about this. Talk to your lab safety people. Get detailed instructions on handling requirements. As for the hood, again, do not ask here, ask your ...
- 14.3k
5
votes
Decreasing signals in assay measurements
Freeze-thaw cycles are often suspected of causing degradation in organic molecules 1,2. My first guess would be that your fluorophore is breaking down due to those repeated cycles. Alternatively, you ...
- 5,613
5
votes
Appropriate cell lines to study depression
tl;dr there is no 'depression' cell line. Cell lines would be suited for studying pharmacology, cellular or molecular mechanisms, none of which are depression. Depression also has no good correlates ...
- 6,272
4
votes
Accepted
Mold identification
I initially figured it was condensation from the agar. But it is not on your lid and you said you suspected humidity was low.
I found this here http://www.gettyimages.ca/detail/photo/mold-...
- 2,964
4
votes
Trypsin and Cell Surface Receptors
Yes. Trypsin cleaves proteins and can do so quite indiscriminately if left on for very long. Trypsin is primarily used to cleave the proteins that cells use to adhere to each other and the plate in ...
- 1,309
4
votes
Accepted
Is there a difference between "cell line" and "cell strain"?
"Strain", in general, is usually used for whole organisms (whether they are unicellular or multicellular). For example, there are mouse strains.
"Cell line", on the other hand, is a very specific ...
- 35.6k
4
votes
Accepted
Why do coliform bacteria smell so bad?
E. coli and other bacteria metabolize tryptophan into odoriferous skatole and other indole compounds.
If you're culturing these organisms in medium that contains tryptophan, that may be what you're ...
- 5,590
4
votes
What is the meaning of harboring cryptic in below sentence?
Harbouring, using harbour as a verb and in this meaning containing/hiding (see 3rd and 4th definitions at Harbour)
Cryptic = hidden/difficult to find - this is how the word is often used in biology, ...
- 12.9k
3
votes
How far is stem cell research from being to generate a new organ?
Sperm can already be generated using stem cells http://blogs.discovermagazine.com/d-brief/2016/02/25/scientists-grow-working-sperm-from-stem-cells/#.V-UADBV94o8
Also, heart, liver and kidney cells as ...
- 3,128
3
votes
Accepted
Did the Hela cells leave John Hopkins
Cultures of HeLa cells are used in many labs around the world, and were widely shared from very early on. From the Wiki:
In the spring of 1953, a cell culture factory was established at
Tuskegee ...
- 3,314
3
votes
What kind of detergent should I use in cell culture laboratory for cleaning purposes?
I agree with Mike, but would like to add that if you are trying to do protein expression for purification, some detergents contain polyethylene glycol (PEG), which will readily bind to many proteins, ...
- 301
3
votes
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Mass production of bacteria
The fed batch culture is a means of bacterial production that is used in industrial setups. Nutrients are fed into the chamber with controlled ideal conditions for growth of a particular species of ...
- 558
3
votes
Why does vacuum sealing of foods prevent spoilage from anaerobic bacteria?
I do not understand why anaerobic bacteria, that don't require and cannot survive in air, do not proliferate and thrive in the vacuum sealed food containers
They do. Vacuum sealing can prevent ...
- 46.5k
3
votes
Accepted
Where can I find a video of human cells reacting to cold water vs warm?
You can't see these changes easily under a microscope. It is a challenge to add heat or cold to cells on a microscope in a manner that you might see, unless you have the right equipment.
You might ...
- 12.9k
3
votes
Accepted
How much effort is it to establish a cytotox assay for cancer cell lines against a small number of possible compounds?
The answer to this is, of course, "it depends". There are quite a few factors at play here. As you don't seem to be experienced at cell culture yet, I strongly recommend that you find ...
- 12.9k
3
votes
Accepted
Cell viability assay: Problems with MTT assay in the solubilization step
The easy answer is to use acidified SDS 10 Percent in 0,01 N HCl. I added this directly, to my media and did not have any problems with crystal removal anymore. The acid will remove the coloring of ...
- 171
2
votes
Will dead cells in culture media have any significant impact on Live cells during incubation?
I'm not sure if this is linked to the actual dead cells, but I've found that not changing the media on plates while trying to generate lines from primary cultures can lead to contamination. Again, I ...
- 31
2
votes
Accepted
"producer cell line" vs. "host cell line" in biopharmacology
I would lean towards staying with "producer cell line". In my mind, a host cell line is hosting something, like a virus, while a producer produces something. The non-transformed cell line would be the ...
- 15.3k
2
votes
Why would you plate cells at different densities in a colormetric assay?
The comments you have given are some reasons, although they also depend on the confluency of the cells. Your teacher/professor/advisor is also making sure that you can see an effect at low levels of ...
- 15.3k
2
votes
Accepted
How to prevent HL-60 cell contamination?
The single most likely reason for the contamination is that your frozen stock is contaminated. Assuming you've been properly trained in cell culture, you're working in a correctly-maintained biosafety ...
- 15.3k
2
votes
Accepted
Estimation of cell count of E.coli culture
You start with $10^6$ cells. After 30 min they double, so there are $2⋅10^6$ cells. After another 30 minutes they double again, so there are $2⋅2⋅10^6$ or $2^2⋅10^6$ cells. After three doubling ...
- 17.8k
2
votes
Accepted
Purpose of dilution streaking or streak purification
The purpose of this technique is to dilute the bacterial cells so much that you get single cells, as can be seen on the image of the plate. You can then pick the colonies grown from these single cells,...
- 52.5k
2
votes
Pipetting damage to cells
I know this is a two-year-old thread, but I though I would post this anyway in case someone else is searching for this answer like I was tonight. This article cited below doesn't discuss pipette tips ...
- 21
2
votes
293T safety, transfections with plasmid DNA
293T cells do incorporate partial virus genomes, consisting of about 4000 bases (about 11%, if I remember right) of the adenovirus type 5 genome (Cloning and Sequencing of the Cellular–Viral Junctions ...
- 14.3k
2
votes
How is an RT-PCR representative of the RNA contents in a cell?
It isn’t really clear exactly what the questioner is asking, but…
...one way of thinking about this is to ask how likely is it that a low-abundance RNA will be absent from the sample taken from the ...
- 22.8k
2
votes
Microinjection intestinal organoids
I found that using the Femtotip loaders gives a continuous block of liquid, which can then be moved to the end of the tip by injecting several times. It is fine to have a air above the liquid at the ...
- 111
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