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Questions tagged [lab-techniques]

Questions relating to protocols, procedures, and good practice when using laboratory equipment.

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1answer
36 views

Why electroporator need a cuvette?

I have never obtain an Electroporator for my home-lab. Because it's very expensive, I'm trying to create a diy cheap version for myself. In all commercial design, I see that we need to put the sample ...
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23 views

How can i confirm the native molecular weight, subunit composition as well as subunit molecular weight of a given protein? [on hold]

I have been given a homodimeric protien of 66000Da of MW. What techniques should i use and in which mannner to determine the the info asked?
2
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1answer
61 views

How to perform cell biology research without lab affiliation [closed]

Related to this question, I am wondering just generally how one can do cell biology research without being part of an already well-established University laboratory. I am not doing this myself but am ...
0
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1answer
41 views

How does the OD correlate with the number of algae cells?

My research team and I are using a spectrometer to measure the OD of an algae sample. We are trying to answer the question "Is there a correlation between OD and the number of algae cells?" What ...
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0answers
54 views

Why do Petri dish lids not fit?

I understand that they are generally "vented", but why such a poor fit? For the batch I bought, the lid and container don't even recognizably go together (like 1/2" difference in diameter). The wind ...
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0answers
36 views

What kind of sieve does one use to extract meiofauna?

Suppose I have a core of sediment, and I want to extract the meiofauna from it, in order to study these organisms. According to the sources I could find, this involves using a very fine (e.g. 45 μm) ...
2
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0answers
34 views

DNA preservation at room temperature

I am considering preserving the DNA of a family member who passed away. The funeral home offers a service called DNA Memories from a Canadian company (CG Labs). They have two options: Store the DNA in ...
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0answers
45 views

Why Cerebrospinal fluid is not heated for VDRL?

For performing VDRL of serum , we heat serum to inactivate complement proteins which may otherwise interfere , but why don't we do same for CSF even though it too has complement proteins in it? Is it ...
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50 views

How is the role of ethylene in ripening demonstrated in biology (or agriculture) education?

I want to know what are some typical experiments performed in the course of biology education (or possibly in applied biology education e.g. agricutlure education) to prove to the students (or have ...
2
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1answer
53 views

When in Ampicillin degraded (gone) in liquid TB-media? Concerns about selectivity

Question: Specifically regarding Ampicillin; When growing cells in TB (terrific broth) for protein expression - when should I expect the ampicillin to be gone due to degradation by b-lactamases? (and ...
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0answers
16 views

Using distilled water on sterile swab for collecting microbes on solid surfaces

I was wondering if it is acceptable to use distilled water on a sterile swab for the collection of microbes on a solid surface. - in this case, Salmonella and Shigella.
2
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1answer
67 views

How can enzymes be immobilised on glass?

I’m studying a hypothetical model for urease activity, which involves fluorescence measurement, hence the need for an optical window to which the enzyme urease is immobilised. From my previous ...
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7 views

Why is it more difficult to measure a decrease in fluorescence in FRET assays?

In the slides, the professor mentions that it is better to use a substrate double labelled with donor-acceptor molecules because we start with FRET quenching and measure increase in fluorescence if ...
1
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1answer
20 views

Can experiments in ELISA kits be monitored via both fluorometry and photometry?

In my bioanalytics course slides, the professor has written at one point that in a heterogenous immunoassay such as ELISA, we use fluorimetry to measure concentration of an analyte. In another slide ...
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0answers
56 views

What are the safety precautions I should take if I want to experiment with C. elegans (at home)?

Caenorhabditis elegans (C. elegans) is a nematode (roundworm), and many nematodes do infect humans and cause diseases. How much is C. elegans safe (or unsafe) in this respect? C.elegans is a popular ...
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36 views

Why is plasma glucose concentration not double that of whole blood?

It is known that the concentration of plasma glucose is 12% higher than that of whole blood. But since 45-50% of whole blood is red blood cells, shouldn't the plasma glucose be almost double — since ...
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0answers
34 views

Control for Bisulfite sequencing

I am wondering how can I control my converted DNA! I converted my DNA with bisulfite then I amplified the converted DNA with specific primers of BSP and purified my product and finally sequenced the ...
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0answers
18 views

Minimum number of cycles for effective qPCR quantification?

I have been having an apparent problem with gDNA contamination in my no-reverse transcriptase (NRT) controls by the appearance of fluorescence peaks in my qPCR data. I have/am trying multiple DNase ...
2
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1answer
203 views

Why shouldn't I clean microscope slides with a paper towel?

I've recently bought a microscope and been looking at a lot of bacteria and such, and have quickly run out of clean slides. I've seen videos and articles saying how you shouldn't clean microscope ...
3
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1answer
178 views

How do you keep track of past/new lab protocols?

Does there exist a list grouped my subject (e.g. 'microscopy') for keeping track of what protocols have been designed and used? Closest I could find is http://www.protocol-online.org/ but it's fairly ...
2
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1answer
26 views

What do the column labels in this table mean?

This table shows the effect of sound (song and tones) on female birds. However, I'm not sure what the labels (F1 22, P and η2) mean. I've seen the labels on other tables too. (from https://www.ncbi....
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15 views

How can I measure the efficacy of RNAi with high sensitivity?

I'm expressing RNAi against some candidate gene using the Gal4/UAS system in Drosophila. I know protein is expressed from the gene in the targeted cell types based on immunostainings, and the good ...
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0answers
36 views

Yeast transformation: is it necessary to remove template plasmid from PCR?

I'm frequently transforming budding yeast with PCR fragments. Normally, after PCR I digest with DpnI to remove the template plasmid. DpnI is a restriction enzyme which cuts methylated DNA, i.e. the ...
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0answers
72 views

Would I expect salt precipitate on fibres of DNA in a NaCl water solution?

I just recently conducted an experiment in my biochemistry class where we had to add DNA to distilled water, isotonic saline and 2.5M NaCl. I noticed different physical aspects depending on the ...
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0answers
7 views

Does removing water from sample affect chemical composition test results?

I have a sample of a (deceased) fungus and I want to measure its nitrate/phosphate composition. The sample is about 30% water by weight, and I'm going to test it by soaking it in diluted water and ...
3
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1answer
206 views

How is the gradient in density gradient centrifugation made?

From the literature I read, I came to understand the following. Please correct me if wrong. In CsCl gradient centrifugation, the gradient is achieved by centrifuging the CsCl solution at high rpm, ...
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2answers
24 views

Do PC-12 cells have to be stored in nitrogen?

My lab has been storing their PC 12 cells in the -80 freezer... upon arriving here and investigating a new project I see that it specifically stated to be stored in nitrogen vapor? Is this the ...
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0answers
87 views

What are the optimal conditions for storing frozen glycerol stocks of bacteria?

The common method of storing bacteria long-term is to collect saturated liquid culture, such as LB, and mix it with sterile glycerol so as to obtain 10-30% final glycerol concentration. The resulting ...
0
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1answer
44 views

How to choose right volume of DNA and SYBR Green

I'm testing fluorescence level of a sample having dsDNA, SYBR Green and milli q water but I'm facing difficulty in choosing right volume of dsDNA and cons level of SYBR Green. Details of sample: ...
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0answers
23 views

Hybridization based technique to detect SNP.

What should be done in order to avoid non-specific hybridization when trying to detect an SNP with hybridization between a probe and sample? Since there is only a single base pair difference, how ...
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0answers
37 views

What are these colonies on my Bacillus pumilus lawn?

I am growing Bacillus pumilus and I have plated some on agar plates. Now I can see some colonies on top of the lawn. Does anybody know what they could be? A contaminant? Bacillus pumilus? I have ...
3
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2answers
92 views

Using nanodrop for analysing biological samples other than nucleotides

I am a 3rd timer postdoctoral fellow with some experience in molecular biology and biochemistry, but major skills in Zoology and Natural History. I am studying some natural extracts, and isolating ...
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0answers
124 views

At what g force do bacteria start to pellet down a tube?

I am working with C. elegans and bacteria and I want to get rid of the bacteria they eat by centrifuging the worms without centrifuging the bacteria. I am using a g-force of 600 and the bacteria ...
4
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1answer
101 views

Test of antibiotic A for sensitivity as surrogate of antibiotic B

I am reading the WHO Global Antimicrobial Resistance Surveillance System (GLASS) - Manual for Early Implementation. it mentioned some of the drug-bug combination that will be put under surveillance in ...
1
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1answer
131 views

Should I use RNAseZAP on my bench and pipettes before RNA extraction?

Should I spray RNAseZAP on my bench and pipettes before working with RNA? I am regularly using RNase at my bench and would like to work with RNA as well. Could traces of RNase on my equipment degrade ...
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0answers
19 views

How to convert a test tube assay to microplate assay?

I am trying to measure Ascorbic acid levels in tissue using Omaye et al protocol (Methods in Enzymology, Volume 62, 1979, Pages 3-11). This method is based on reduction of ferric chloride and ...
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0answers
28 views

What is known and what can be measured of biofilms?

Context for the question I am a mathematics researcher working on the mathematics of imaging and parameter estimation (inverse problems). I found an interesting diffusion equation that models the ...
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0answers
22 views

Reference article to typical Proteins in E.coli (identify bands in SDS-PAGE)

I am curious to know if there are any reference articles that sum up typical protein bands that you get from protein expression in E.Coli. I know that you can do some lab work and experimentally find ...
4
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1answer
110 views

DNA quantification in a high school bio lab

I'm working on a project in a high school bio lab (so limited resources), and I need a way to quantify the concentration of DNA in a PCR product. I can't use spectrophotometry (cheap ...
0
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1answer
34 views

Why marker and control are loaded in the beginning or ending lane of the gel?

I have seen gel images in several literature. Almost in all, markers and controls are loaded in the extreme lanes (before 1st sample or after last sample) of the gel. I am just curious, is there any ...
9
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2answers
703 views

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

Recently I have started in a new microbiology lab, and with a new lab come new habits. When I was working with my bacterial (liquid) culture next to the flame (Bunsen burner) wearing nitrile gloves, ...
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69 views

How to increase the yield of cfdna extraction?

I use Qiagen circulating nucleic acid kit for extraction of cfdna. Many times I got low concentration of cfdna or sometimes I got nothing. Can I add extra amount of carrier RNA to get high yield cfdna?...
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30 views

What does having no consensus symbols in a ClustalX2 alignment mean?

I have completed a full sequence alignment of 30 tyrosinase sequences using ClustalX2, yet there are no consesus symbols above the data like there normally is. I think it has run correctly, but am not ...
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0answers
41 views

Can anyone expolain this? Cell culture vials have strange hair-like condensation patterns

What is the hair-like polymer that condenses on the caps of the plastic cell vial? Inside vial are cells in a mixture of FBS and DMSO. The vials were frozen slowly in a special isopropanol-filled ...
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1answer
32 views

HELP hepes preparation [closed]

I need help: I would like to prepare an HEPES solution, without using the powder. It is possible? I remember that I did it once, but maybe I'm wrong...does someone know a protocol for HEPES ...
5
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1answer
136 views

Optimization of Signal Peptides

We are looking at modifying the signal peptide of a receptor in a common immortalized human cell line. The cell line already expresses an unusually high amount of the protein, but much of it is not ...
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0answers
131 views

How to keep Paraffin Sections from falling apart?

I've been trying to make 5 uM sections of injured mouse spinal cords and stain the tissue with Luxol Fast Blue and H&E. At first I was removing the bones from around the spinal cord, but the ...
3
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2answers
598 views

Agarose gel Ladder smear

We are having trouble with agarose gel electrophoresis. It used to work a couple of months ago but now the ladder always look smeared. We switched the components (1x TBE, 100bp ladder, different type ...
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0answers
69 views

What happens during fixation of Nucleic acids on nylon membrane

In Southern blotting technique, fixation of DNA to nylon membrane is a step prior to hybridisation with probe. It is done by baking at 80ºC and according to this cross linking between DNA and nylon ...
9
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1answer
2k views

What is the role of glucose in plasmid isolation?

My understanding is that glucose is used in the resuspension solution to prevent cells from bursting by maintaining the appropriate osmotic pressure. Why do we even bother doing this? The cells are ...