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23 votes
Accepted

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 ...
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 ...
14 votes

Doing a medical study on yourself?

One of the cornerstones of research ethics worldwide is the Nuremberg code, which was formulated shortly after the Second World War and set off by the cruelties performed by the Nazi Doctors. The ...
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11 votes
Accepted

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 ...
  • 17.6k
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 ...
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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 ...
6 votes
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How can I convert plate reader measurements of Pichia pastoris OD to cells per ml?

From a technical perspective, for the FlopR package you mention (and I believe also for Jacob Beal's protocol) you can simply change the bead size and perform a new calibration. The only information ...
5 votes
Accepted

Is there a term for a procedure in which the chromatography column is washed with 20% alcohol

Prepared or conditioned for storage would probably be perfectly acceptable. If you're looking for a single-word equivalent, in this case, I would translate as stabilized. From dictionary.com: ...
  • 166
5 votes

How are the physiological properties of mitochondria measured?

A simple method would me to express a fluorescent protein in the cell that specifically localizes to mitochondria. mito-dsRed is a Red Fluorescent Protein which has that property; it can be expressed ...
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5 votes
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Do all plants grow roots when separated from parent?

Dear respected person, I am not a professional botanist, but I adore gardening, and would like to help you as much as I can from my humble garden experience. As far as I have experienced, not all ...
  • 506
5 votes
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The information carried by nerve signals

Neural info is contained in spike trains, mainly in terms of spike frequency and related parameters. These spike trains in individual neurons can be measured by techniques like patch clamp and Ca2+ ...
  • 51.8k
5 votes

Why are IMAC and gel filtration combined?

Without knowing your specific protocol, it is common to use more than one purification method for a single protein. Given the broad similarities that all proteins and even most biomolecules share, it ...
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4 votes
Accepted

How to best conserve a beetle inside a jar?

The answer to this question depends on how you want to preserve it - as a pinned specimen (also dry preservation, most common) or in a liquid. If you want to pin it, placing it in a jar with a ...
4 votes
Accepted

How can I reduce the background gradient in phase contrast microscopy?

If you're not already doing so, make sure you set up Kohler illumination every time you use the microscope -- see this tutorial by Steven Ruzin. The lamp or the phase ring may be misaligned. There ...
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4 votes
Accepted

How does one experimentally obtain a hemoglobin-oxygen dissociation curve?

There are existing instruments commercially available to measure hemoglobin-oxygen saturation curves. Whole blood or lysed blood can be used; I would expect the instrumentation to come with specific ...
  • 40.1k
4 votes

How do bull semen companies get the semen out of the bulls?

Colorado State University has two helpful pages that explain the main procedures (h/t Tom). Semen Collection goes through the 3 ways that are used to collect semen from animals. Semen Collection from ...
3 votes

How do you test soil for the nutrients present in it?

Send soil samples to a soil lab (e.g., here). They will likely use the Mehlich III extractant method to extract and quantify the nutrients (most importantly the bases such as Ca, Mg, K, and Na). ...
3 votes
Accepted

How do you determine the length of an annelid?

Leeches: According to Taube (1966)$^1$: The adults of American leeches range from about 1/4 inch to 12 inches in contracted length. Because leeches can bloat to more than 10x their "normal"...
3 votes
Accepted

Using catalase-test to determine if Staphylo- or Streptococcus

Generally yes: streptococci are catalase negative while staphylococci are catalase positive. The catalase test is important in distinguishing streptococci (catalase-negative) [from] staphylococci ...
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3 votes

What does it mean when you "extract the filtrate with ethyl acetate three times?"

This procedure is referring to chemical extraction, which is a separation process used in chemistry (and biochemistry) to isolate compounds of interest by using two immiscible phases in which the ...
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3 votes
Accepted

Measuring body size in flies/insects

I think you are correct, but I'm not an expert in Diptera/Drosophila morphology. Since the prothorax (pronotum) and metathorax are greatly reduced in flies, you mostly see the mesonotum in dorsal view,...
3 votes
Accepted

What are the units of Phylogenetic Independent Contrasts (PICs)

From what I understand, the answer is; it depends. As you point out in the comment to Remi.b, contrasts are standardized by branch lengths (which are assumed to be proportional to "evolutionary time") ...
3 votes

LCMS/MS versus Western Blot

Western blot, though is a commonly used technique and is relatively simple to do, has some issues: Low throughput: it is difficult to analyse multiple proteins simultaneously Limited cross ...
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3 votes
Accepted

What are wave frequencies in the EEG?

EEGs are often analyzed in the frequency domain, where signals are subjected to spectral analysis, typically by Fast Fourier Transformation, or FFT. What an FFT basically does is decomposing a ...
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3 votes

What is the effect of the wavelength on the spectrophotometric measurements of protein?

Light absorption happens because of interaction of light with electrons (in a way) such that the energy of the light is transferred to some electrons that moves them to a higher energy state. As per ...
  • 35.2k
3 votes

Agarose gel Ladder smear

Are you sure that your TBE is at the right dilution? And that you're using TBE to make the gel and also as the buffer for running? That sort of wavy line looks like what you might get if you'd made ...
  • 41
3 votes

Double Digestion with Restriction Enzymes Using Different Buffers

NEB double digest planner is suggesting to use 2.1 buffer for your combination of restriction enzymes (XmaI 50% and KpnI 75% activity). I would be more worried about the star activity of KpnI in ...
  • 573
3 votes

Double Digestion with Restriction Enzymes Using Different Buffers

If you haven’t already ordered your enzyme, you could get high fidelity KpnI, which has been engineered for use in CutSmart. You could also consider doing a sequential digest rather than a double ...
  • 17.6k
3 votes
Accepted

Double Digestion with Restriction Enzymes Using Different Buffers

In my experience, a double digestion in CutSmart buffer will work perfectly well. The reaction may proceed slower, but incubate it a little longer and run a gel after the digestion - you'll see ...
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3 votes
Accepted

Is there a difference between ISH and ISHH? (In Situ Hybridization, In Situ Hybridization Histochemistry)

The term appears to be in use as a synonym. PLOS ONE is a good journal, and in it Okubo, 2016 write "The protocol for ISHH was described in detail previously [22]." Where [22] is Yamanaka, ...
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