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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 ...
ksdjnf's user avatar
  • 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 ...
Raghu Parthasarathy's user avatar
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)....
WYSIWYG's user avatar
  • 35.6k
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 ...
iayork's user avatar
  • 14.2k
6 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 ...
iayork's user avatar
  • 14.2k
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 ...
tyersome's user avatar
  • 5,598
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 ...
S Pr's user avatar
  • 6,262
4 votes
Accepted

Do bacteria grow on pure dry glucose?

Bacteria or other microorganisms cannot really grow on anhydrous (totally dry) glucose because they need water. However, they can remain there and cause contamination. Even if you haven't actually ...
WYSIWYG's user avatar
  • 35.6k
4 votes
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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 ...
WYSIWYG's user avatar
  • 35.6k
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 ...
akaDrHouse's user avatar
  • 1,309
4 votes
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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-...
Willk's user avatar
  • 2,964
4 votes
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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 ...
Alex Reynolds's user avatar
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, ...
bob1's user avatar
  • 12.4k
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 ...
Chimango Chisuwo's user avatar
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 ...
alec_djinn's user avatar
  • 3,108
3 votes
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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 ...
bshane's user avatar
  • 3,304
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, ...
Ema's user avatar
  • 301
3 votes

What kind of detergent should I use in cell culture laboratory for cleaning purposes?

I can't tell if you're asking about glassware or work surfaces (hoods, benches etc), but... We use regular old dawn dish soap in my lab because what's more important than the soap you use to wash you'...
Mike's user avatar
  • 31
3 votes
Accepted

Can you replace glucose with glycerol in cell media?

In most cases, it's not a good idea to replace glucose with glycerol in animal cell media. Animals do possess the ability to metabolize glycerol, via a pathway starting with the enzyme glycerol kinase....
Sean Johnson's user avatar
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 ...
Bryan Krause's user avatar
  • 45.9k
3 votes
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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 ...
bob1's user avatar
  • 12.4k
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 ...
bob1's user avatar
  • 12.4k
2 votes

Confluency or confluence, which term is correct to describe the % area covered by cells?

Searching Google Scholar for cell confluence returns 239000 hits, while searching for cell confluency returns 75000 hits. A look at the context in which they are used supports my gut feel, which is ...
March Ho's user avatar
  • 9,452
2 votes
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Respiration of an animal cell media

Supply of cells growing in adherent culture is unproblematic, as long as you don't fill too much media in the petri dish/cell culture flask. Oxygen supply here work by diffusion which is getting more ...
Chris's user avatar
  • 51.7k
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 ...
CAL's user avatar
  • 31
2 votes
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"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 ...
MattDMo's user avatar
  • 15.3k
2 votes
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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 ...
canadianer's user avatar
  • 17.8k
2 votes
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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,...
Chris's user avatar
  • 51.7k
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 ...
Adam McInnes's user avatar
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 ...
MattDMo's user avatar
  • 15.3k

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