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Derek Davies

Derek gained his Bachelor’s Degree in Animal Physiology and Nutrition from the University of Leeds.

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Articles by Derek Davies

flow cytometrists

Five Things That Irritate Flow Cytometrists

By Derek Davies | November 13, 2017

I have worked in flow cytometry for a number of years. I’m still annoyed that many myths and imprecisions are perpetrated and perpetuated. Here is my non-exhaustive list of cytometry-related beliefs that send flow cytometrists screaming from the room or at least, being English, make me tut sadly. Forward Scatter Equals Cell Size No No…

Chromosome Analysis by Flow Cytometry

By Derek Davies | April 27, 2017

In most people’s minds a flow cytometer can sort, view and count cells e.g. lymphocytes, thymocytes, cultured cells and even non-mammalian cells such as yeast or bacteria. However, in reality, a flow cytometer is capable of providing information about any particle as long as it has detectable fluorescence. This fluorescence may occur either inherently or…

Detection of Apoptosis by Flow Cytometry: To Be or Not to Be

Detection of Apoptosis by Flow Cytometry: To Be or Not to Be

By Derek Davies | October 4, 2016

Sometimes only a small subset of a cell population will show apoptotic features making flow cytometry an excellent way to identify and quantify them. A previous Bitesize Bio article showed how flow cytometry can detect apoptotic hallmarks. More than 30 different dyes can be used to detect apoptosis. It is also true to say that…

The Exciting (and Emitting) World of Fluorescence

The Exciting (and Emitting) World of Fluorescence

By Derek Davies | July 9, 2016

Flow cytometry is a fluorescence-based technology, as is fluorescence microscopy and confocal microscopy. Fluorescence is fundamental to how a cytometer gathers data, but I am often surprised, as a core manager, at how little new users know about the process of fluorescence. So, this is where I always start the training process. Let’s get physical…

Thresholding in Flow Cytometry – Why It Is Important

Thresholding in Flow Cytometry – Why It Is Important

By Derek Davies | July 9, 2016

Flow Cytometry is a great way of seeing how many of your cells express a particular marker and how much of it is there. We do this by measuring fluorescence, but, as with all measuring systems, there will be signal that we are always trying to measure the above the noise. The signal that we…

cell cycle analysis

Cell Cycle Analysis by Flow Cytometry: Flowing your Way through Life’s Cycle

By Derek Davies | July 9, 2016

Over the past few decades the mammalian cell cycle has been well documented. Although there are lots of checkpoints as cells move through the cycle, we can very simply divide the cell cycle into three stages according to the DNA content in the nucleus. When cells are either quiescent or not dividing they have the…

Putting Down a Marker in Flow Cytometry to Help Determine Positivity

Putting Down a Marker in Flow Cytometry to Help Determine Positivity

By Derek Davies | June 16, 2015

In many biological experiments the question that a researcher wants to ask is – ‘do some or all of my cells express a particular protein?’ There are many ways of doing this, which you will be familiar with e.g. Western blotting, immunoprecipitation, microscopic examination of stained cells and even mass spectrometry. Using Flow Cytometry to…

Basic Statistics for Flow Cytometrists - Part 1

Basic Statistics for Flow Cytometrists – Part 1

By Derek Davies | April 21, 2015

Part of my job in running a core flow cytometry facility is to make sure that the experiments that my users run have been optimised. But that optimisation can be split up into several areas. The first area is experimental planning: What do you want to know? Can you do this by flow cytometry? And…

Data Spread and How to Measure It: the Coefficient of Variation (CV)

Data Spread and How to Measure It: the Coefficient of Variation (CV)

By Derek Davies | March 17, 2015

No matter how we make measurements, there will be variation (a spread of data). Take 100 people and ask them to guess your age and you will get a range of results: some will be too low (excellent!), some too high (not so good!). It is the same with any of our laboratory experiments –…

Viability Dyes for Flow Cytometry: It’s Not Just a Matter of Life and Death

Viability Dyes for Flow Cytometry: It’s Not Just a Matter of Life and Death

By Derek Davies | January 6, 2015

As Morrissey once sang “in the midst of life we are in death, etc.” A fact of life in the research Lab is that whenever we run an assay there will almost certainly be some cell death in our sample. This may be insignificant in some techniques but in others it can be problematical. Why…

Fixation and flow cytometry

Fixation and flow cytometry

By Derek Davies | November 18, 2014

Fixation is routinely used in histology and cytology Labs the world over as a way of keeping cells in stasis at a particular point to ensure that, by the time they are examined, they have not deteriorated. This is also something that we often want to do in flow cytometry experiments. It seems like a…

Using Flow Cytometry for Cell Proliferation Assays: Tips for Success

Using Flow Cytometry for Cell Proliferation Assays: Tips for Success

By Derek Davies | October 14, 2014

We all know, generally from bitter experience, that experiments don’t always work first time and that sometimes the little things that govern success are the things that get left out of that online protocol! So whether you are assessing proliferation by nucleotide incorporation or by dye dilution, here are some handy hints to help you…

Cell Proliferation Round 2 And Beyond: The Dye Dilution Method

Cell Proliferation Round 2 And Beyond: The Dye Dilution Method

By Derek Davies | August 5, 2014

Like the legendary fight between boxers Bowen and Burke in 1893, the cell cycle in some cells goes on and on..round 1, round 2, round 3, round 4…before the final bell is rung. Nucleotide analogs, like BrdU or EdU, are great for examining 1-2 cell cycle division(s).  In many studies though, for example the proliferation…

Cell Proliferation Round 1: Using Thymidine Analogs With Flow Cytometry

Cell Proliferation Round 1: Using Thymidine Analogs With Flow Cytometry

By Derek Davies | May 20, 2014

Around and around the cell cycle goes, where it stops, nobody knows. Unless you have the right tools to analyze DNA content, that is. The DNA markers propidium iodide, Hoechst and DAPI are commonly used in flow cytometry to analyse a cell’s DNA content.  Although they are simple to use, they do have disadvantages. Figure…

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