29 votes

Why does an autoclave need to pressurize steam?

An autoclave can sterilize both solids and liquids, whereas an oven with no pressure control is typically not suitable to sterilize liquids. Not only do you need to heat the chamber to 121°C, but you ...
Mowgli's user avatar
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26 votes

How long will a typical bacterial strain keep in a -80°C freezer?

Richard Lenski's lab at Michigan State university has been doing long-term evolutionary research on E. coli and maintaining a "frozen fossil record" of their experimental populations every ...
MikeyC's user avatar
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23 votes
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Pipetting: do human experimenters need liquid class information?

In my experience it is very rare to see a protocol for humans that describes how to pipette a certain liquid, but I don't have as many years pipetting as others do. In general, it is left to the ...
Noah Sprent's user avatar
23 votes

Pipetting: do human experimenters need liquid class information?

I work on software that controls one model of robotic pipetter. There are a few reasons why we use complex liquid class definitions: One of the selling points of using a robot is high speed. You ...
Dan Bryant's user avatar
15 votes

Are bleach solutions still routinely used in biochemistry laboratories to rid surfaces of bacteria, viruses, certain enzymes, and nucleic acids?

I'm a research post-doc working in a US-based microbiology research lab. We still use a relatively low-concentration bleach solution to decontaminate most liquid cultures before disposing of them, but ...
MikeyC's user avatar
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13 votes
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Assembling small DNA parts using Golden Gate

Purely going off experience here having used golden gate assembly methods for 5+ years now, there is a definite lack of literature regarding small part assemblies. In my current lab, we use CIDAR ...
J.E.Bird's user avatar
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12 votes
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What is the role of glucose in plasmid isolation?

This is a common misconception: in fact, in the alkaline lysis method for plasmid isolation, the glucose does not act as an osmotic stabiliser. Glucose is present in the resuspension buffer at 50 mM. ...
Alan Boyd's user avatar
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11 votes

Good pipetting technique?

Here's some step-by-step advice on good pipetting technique: Make sure the pipette is set for the correct volume Ensure the tip is firmly attached Keep the pipette vertical when pipetting Slowly and ...
rg255's user avatar
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11 votes
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How long will a typical bacterial strain keep in a -80°C freezer?

The reason you haven't found a definitive answer is that it depends on several factors. The first factor that comes into play if we consider only ultra-low freezers (- 80 °C) is the organism you're ...
GaelC's user avatar
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11 votes
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What's happening in the "C" and "T" stripes of a covid test kit?

This is a lateral flow assay. [image source] A sample is applied at one end of the strip and flows across to the other side by capillary action. It first encounters antibodies against the target ...
canadianer's user avatar
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10 votes

Are bleach solutions still routinely used in biochemistry laboratories to rid surfaces of bacteria, viruses, certain enzymes, and nucleic acids?

I can only speak from my experience in many labs in different countries: We never used bleach for cleaning or disinfecting surfaces like cell culture hoods or lab benches. For this purpose we ...
Chris's user avatar
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10 votes
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Saturated Mutagenesis Screening

This sort of method is indeed quite useful and frequently used in synthetic biology: I've used a similar approach before to generate 5' insulators for promoters. Calculating the exact theoretical ...
jakebeal's user avatar
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10 votes
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Tips for longer fragment size and higher purity of insect DNA

Insect samples are difficult to work with primarily because they contain a bunch of polysaccharides, like chitins, that are similar enough to nucleic acids that they can co-precipitate. Standard ...
bob1's user avatar
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9 votes
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"X" in stock solutions

1x is the final working concentration of the solution (it could be anything depending on the type of the solution). Stock solutions are made at a higher concentration; if it is 10 times more ...
WYSIWYG's user avatar
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9 votes
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Why spin live fruit flies in centrifuge?

Correction of Poster’s Source The article cited mistakenly refers to centrifugation, however the actual procedure used in the work — Karageorgi et al. Nature, 2 Oct 2019 — is vortexing, as ...
David's user avatar
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9 votes

Alternative dyes for Gram staining

As you may have realized, crystal violet can be replaced by a lot of dyes since the ethanol will wash out the dye from the gram negative cells. Methylene blue is a nice choice - malachite green may ...
Traci's user avatar
  • 201
8 votes

Is working with (nitrile) gloves around a bunsen burner safe?

new microbiology lab What're the entry requirements for your lab? If you're working in BSL-2 or greater, the appropriate PPE ensemble is listed and required at all times while you're in there. ...
CKM's user avatar
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8 votes

Measuring luminescence in a fluorescence plate reader

I am René Inckemann and I am PhD student at the Max Planck Institute in Marburg, Germany. In my PhD I am using luminescence on a regular basis and I was also responsible to organize some of our ...
Rene Inckemann's user avatar
8 votes
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Measuring luminescence in a fluorescence plate reader

As the other answers here say, technically plate readers which are capable of fluorescent measurements can also make luminescent readings, but the sensitivity may be low (https://www.biotek.com/...
Brad0440's user avatar
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8 votes

Assembling small DNA parts using Golden Gate

I don't have hard data to share regarding you question, but I can provide some anecdotal evidence. I have used golden gate assembly to build hundreds of plasmids using ~20bp annealed oligos, as well ...
compsynbio's user avatar
7 votes
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Why calf thymus DNA is widely used instead any other body part?

I have crawled through google and many, many journal articles. What I can make of it, is: "It is generally agreed that from mammalian cells (as, for example, calf thymus..." are capable of yielding ...
GrumpyMammoth's user avatar
7 votes
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Measuring protein concentration, Bradford vs. Nanodrop?

That depends strongly on your protein and how exact you need this concentration. Both tests (Bradford and the measurement at 280nm) only do an approximation. The measurement at 280nm relies on the ...
Chris's user avatar
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7 votes

Sterilize/disinfect sugar for lab use

Autoclaving media with carbohydrates (or sugar solutions on its own) is not a good idea for two reasons: The Maillard reaction: This occurs when you heat mixtures of amino acids and sugars. The ...
Chris's user avatar
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7 votes

Is working with (nitrile) gloves around a bunsen burner safe?

Wearing gloves increases the risk of injury when working next to an open flame since they can melt onto your hand. Not wearing gloves increases the risk of infection when working with pathogens. As ...
canadianer's user avatar
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7 votes

Pipetting: do human experimenters need liquid class information?

Just to be clear, it has been many years since I have done real lab work, so I am certainly not an expert on the specific question. However, I have a fair amount of experience writing clear ...
apc's user avatar
  • 71
6 votes

Measuring protein concentration, Bradford vs. Nanodrop?

The nanodrop should have an option that allows you to input an "extinction coefficient". This is a measurement of how much one mole of your protein will absorb at 280nm. The nanodrop will use this ...
Joe Boyle's user avatar
6 votes

Are vacuum centrifuges the same as normal centrifuges?

A "normal" centrifuge = piece of laboratory equipment, driven by a motor, which spins liquid samples at high speed to allow centripetal acceleration to separate substances of greater and lesser ...
theforestecologist's user avatar
6 votes
Accepted

1% water solution of deoxycholic acid. How is it prepared?

According to the sigma document you referenced (emphasis added by me): "The free acid is soluble at 0.24 g/L in water at 15ºC, while the sodium salt is soluble at >333 g/L in water at 15ºC. ...
MikeyC's user avatar
  • 4,714
6 votes

Are bleach solutions still routinely used in biochemistry laboratories to rid surfaces of bacteria, viruses, certain enzymes, and nucleic acids?

Bleach also destroys DNA/RNA, and kills bacteria, making it useful in an area where PCRs are done. 70% ethanol is very friendly to DNA, but it kills bacteria well enough. My guess for the preference ...
user168345's user avatar
6 votes

Tips for longer fragment size and higher purity of insect DNA

I think @bob1's answer is good, and covers a lot of the bases. One thing that I think is missing however is the use of a nuclear preparation as an initial step- my understanding is that this can help ...
Maximilian Press's user avatar

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