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 ...
- 634
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 ...
- 471
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 ...
- 17.8k
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 ...
- 71
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 ...
- 30.3k
6
votes
Accepted
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 ...
- 474
5
votes
Accepted
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+ ...
- 52.6k
5
votes
Accepted
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
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
Why choose strawberries for DNA extraction?
There's more than one reason behind the use of strawberries:
They are octoploid (8n), so they have eight copies of each chromosome per cell, i.e., there is a
lot of DNA to isolate per unit of volume;
...
- 52.6k
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 ...
- 17.8k
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 ...
- 46.5k
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 ...
4
votes
Accepted
Change of DNA concentration due to restriction digest?
Summary
The poster wishes to know why spectrophotometric readings (presumably absorbance at 260 nm) on a sample of genomic DNA from an unspecified organism appear “slightly” greater after incubation ...
- 26.3k
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
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 ...
- 46.5k
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"...
- 30.3k
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 ...
- 17.8k
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 ...
- 583
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 ...
- 17.8k
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 ...
- 6,272
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, ...
- 2,485
3
votes
Accepted
T-vector creation
Personally I would use Taq DNA polymerase to A overhang my inserts, especially if you are PCR amplifying the insert. It leaves an A overhang on the end of all amplicons natively. All you have to do ...
- 12.9k
3
votes
How do we know if a trait is genetic rather than via rearing environment?
It's purely and simply that there is no single answer - as in the linked paper, there's no "gay gene", there is a group of identified genes that contribute, but not all the variance in the ...
- 12.9k
3
votes
RNA sequencing and taxonomic analysis of gut microbiome
The article that you link to clarifies in the methods section that there are two different extraction protocols employed, one for 16S information (probably DNA extraction) and one for total RNA. In ...
- 10.5k
3
votes
Change of DNA concentration due to restriction digest?
As you did a clean up, then you lost some DNA in this process. There are always losses from clean up steps.
Note also that spectrophotometry is notoriously unreliable for DNA quantitation; it's more ...
- 12.9k
2
votes
Is there a term for a procedure in which the chromatography column is washed with 20% alcohol
This is a routine procedure in FPLC to prepare columns for storage. 20% ethanol is used to prevent microbial growth. See this technical note:
All SEC columns are delivered in 20% ethanol to prevent ...
- 17.8k
2
votes
Accepted
Well Plate Method VS Kirby Bauer Method
I came across a nice Master's thesis that investigated precisely that. The conclusion reads as follows:
Automated microbroth dilution-based testing methods are increasingly used by many
clinical ...
- 1,519
2
votes
Accepted
How is the flicker fusion rate interpreted as an on-off rate?
Short answer
A light flashing at 50 Hz means there are 50 flashes of light per second. The unit hertz means cycles per second. 1 cycle is the time it takes for the light to be ON and OFF. 50 Hz cycle ...
- 52.6k
2
votes
Phylogenetic Independent Contrasts with discrete traits
Assuming that by "discrete", you mean "discrete and ordinal" (like 2, 21, 7, 12) and not "discrete and nominal" (like ...
- 68.3k
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