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Search below to delve into the Bitesize Bio archive. Here, you’ll find over two decades of the best articles, live events, podcasts, and resources, created by real experts and passionate mentors, to help you improve as a bioscientist. Whether you’re looking to learn something new or dig deep into a topic, you’ll find trustworthy, human-crafted content that’s ready to inspire and guide you.
These days, epigenetics is a fast moving field. I don’t remember having learnt about it during my biomedical studies, some 10 years ago. Nowadays, there seems to be no way around it when studying health and disease. Increasing interest combined with recent technological breakthroughs have led to quickly expanding knowledge of its abundant and important…
A young laboratory technician was puzzled by his plates when he pulled them out of the warm room. They never looked that cloudy and fuzzy before. He brought them to his lab director, who shook her head sadly; together, they threw the plates away. Does this story sound familiar? What probably happened was an all-too…
Mycoplasma infections are very, very bad news; these special prokaryotes can rapidly spread through your cell culture and inhibit cell proliferation, induce apoptosis, cytokines and radicals, and otherwise transform your cells. Worst of all, since contamination is not easy to spot, you may not realize your culture is contaminated until it’s too late. The 100…
Commercial kits for isolation of large quantities of plasmid DNA generally rely on standard alkaline lysis followed by an affinity chromatography column-based method to purify DNA. Compared to traditional cesium chloride banding or PEG precipitation of plasmid DNA they are a breeze, and have the added benefit of avoiding use of toxic or hazardous chemicals…
Western blots may be great for visualizing protein expression, but they can be a perfect way to waste your precious antibody stocks if you follow the normal protocol. Thankfully, you don’t have to follow the normal protocol any more; here’s how to get great blots with a fraction of the antibody usage. I have tried…
You’ve masterfully run and transferred your gel, and now it’s time to probe and quantify your protein(s). You’ve got your antibodies and ECL ready to go. Substrate – check. Film cartridge – check. Darkroom – ah yes, that magical place where night vision goggles are required to navigate a veritable minefield of potential chaos. It…
Epigenetics is the study of heritable changes in the phenotype of a cell or an organism that are not encoded by the genome (hence epi which means ‘above’ in Greek, and genetikos which means ‘origin’). In this article, we’ll discuss DNA methylation, a common epigenetic modification: what it is, how to detect it, and how…
When running a quantitative Western blot, it’s crucial that your sample preparation is consistent. Incomplete protein extraction from one sample will skew your results when you compare it to the protein content of a sample that was extracted more thoroughly. And after the protein extraction, it’s important to handle the samples in an identical manner…
Working with RNA? What fun! Those little, nearly indestructible RNases are everywhere – on your skin and mucous membranes, in the water and (some of the) enzymes you use, on lab surfaces, even in airborne microbes! Here are 10 ways to keep the RNases at bay, and keep your precious samples safe:
When it comes to choosing a molecular weight marker to run on your SDS-PGE gels, there are a lot of options out there. How do you know which one is right for you? Read on for tips on what to consider when choosing a standard for your protein gels. Before you go about selecting a…
So, you’ve done your experiment, prepped your samples, and run your SDS-PAGE gel. Now it’s time for the all-important transfer step, that tricky point that will determine the quality of your Western blot. Transfer times are empirical and based on your own particular samples, which means that there is no easy way to determine how…
I think that transferring Western blots is one the most enjoyable tasks to do in a lab: it’s quick, it’s messy, and on some gleeful level, it feels like a child’s art project gone wrong. Of course, it’s also finicky and slippery and prone to tiny pitfalls that can noticeably affect the quality of your…
For Western blot data to be reliable, it is important that you load known amounts of sample into each lane of the gel. This is of particular importance if you are doing a quantitative blot, where you really need to be able to compare band intensity in each sample. In this article, we’ll talk about…
While Luria-Bertani broth (LB) has long been the fuel that powered Molecular Biology and Biochemistry, there is an increasing movement towards more specialized and complex bacterial media formulations such as Terrific Broth (TB), Plasmid DNA Media (PDMR), and Autoinduction Media (ZYP-5052). These media formulations optimize E. coli cell growth and performance utilizing specialized carbon sources…
I recently introduced you to the concept of polarising microscopy. Naturally, if evaluating refractile material is an everyday part of your research, it is definitely worth investing in a professional polariser modification for your microscope. But if you only use a polariser occasionally, this might not be the best use of your lab’s money. In…
Tandem affinity purification is a development of existing techniques for purifying protein complexes from cells in physiological conditions. It was first described over ten years ago and has become a commonplace laboratory tool. In this brief article I’ll introduce the basic technique and describe some of its advantages. Biology is a team game. Most biological…
When you stop to think about it, tissue slices for immunohistochemistry (IHC) undergo quite a lot of handling. From chemical reactions to washes – even manipulations and transfers between baskets and microtubes – final analysis is often hours away from the initial step of taking a tissue slice. Properly fixed tissue has to be robust…
Polarising microscopy involves the use of polarised light to investigate the optical properties of various specimens. Although originally used predominantly in the field of geology, it has recently become more widely used in medical and biological research fields too. Polarising light microscopy is a contrast-enhancing technique to allow you to evaluate the composition and three-dimensional…
There’s more to mammalian cell culture than just making sure that your cells don’t die. It is a lot like taking care of children. You have to feed them, make sure that they’re growing well, and keep them under constant supervision. If the cells are put through extreme conditions (over-confluency, media-deprivation, inaccurate temps, etc.), their…
Do you use human cell lines in your research? Well, keep reading because this may be the most important article you will ever read in your research career. It is estimated that 18-36% of all actively growing cell line cultures are misidentified and/or cross-contaminated with another cell line (1). For researchers, this could mean that…
Microarrays are one of the most in-depth ways of determining cellular gene expression levels of thousands of genes simultaneously. They are able to help determine: Getting good microarray results starts way before analyzing your data, however. A crucial first step in setting up a good microarray experiment is extracting high-quality RNA from your cells. In…
For applications such as site-directed mutagenesis, it is often recommended that you use a proofreading polymerase (also known as high-fidelity polymerases) to minimize the risk of introducing unintended point mutations. But what is a proofreading polymerase? What makes them different from other polymerases? And when should you use them? Read on to learn more… What…
Most site-directed mutagenesis protocols strongly recommend that you use only PAGE- or HPLC-purified primers to mutate plasmid templates. Using purified primers is supposed to minimize the introduction of unintended mutations, thus drastically improving the probability of generating your desired mutant. However, specially purified primers can be extremely expensive, and take longer to synthesize than standard…
RNA interference (RNAi) may have originated as a defense mechanism to protect cells against foreign genes introduced by viruses. This concept has since been put to use to create a powerful experimental tool for investigating gene function in organisms. Small-interfering RNA (siRNA) libraries for investigating genome-wide function can be produced by chemical synthesis of probes…
ELISAs (enzyme-linked immunosorbent assays) are often used for detecting and quantifying substances such as peptides, proteins, antibodies and hormones in research and diagnostics. Today, a wide range of ELISA formats exist to suit your needs e.g. indirect ELISA, direct ELISA, competitive ELISA and sandwich ELISA. While it has become easier to perform ELISAs, thanks to…
Although the microscope is probably the most commonly used biological instrument, it is frequently used improperly. The rate-limiting step to getting high quality microscopic images is illumination of your specimen. When you examine a specimen under the microscope, the intensity and distribution of light must be clear and equal to enable you to evaluate all…
The presence of supercoiled plasmid DNA on a gel can be inconvenient for molecular biologists, especially beginners because it is easy to misinterpret. Read our top tips how to recognize supercoiled DNA and keep it from derailing your cloning experiments.
If you’re starting your PhD or post-doctoral work, chances are you’ll need to use a light microscope at some stage during your research. Some of you may be seasoned microscopists. For many of you though, this might be the first time you’ve ever plugged in a microscope, or at least the first time you’ve used…
ChIP-seq is a wonderful technique that allows us to interrogate the physical binding interactions between protein and DNA using next-generation sequencing. In this article, I’ll give a brief review of ChIP and introduce the chromatin immunoprecipitation sequencing technique (ChIP-seq), which combines ChIP with next-generation sequencing. What is chromatin immunoprecipitation? Chromatin immunoprecipitation (ChIP) allows us to…
If your immunohistochemistry is not working quite as expected, don’t fret. Check out this comprehensive guide to troubleshooting immunohistochemistry.
Have you ever wished you could transfer the same SDS-PAGE gel twice? Sometimes, when you are blotting for many different proteins of similar size, stripping and reprobing multiple times can become impractical. Here’s a simple diffusion transfer method that can be used to generate duplicate membranes from a single gel: Protein transfer by this diffusion…
Phosphorylation is one of the major post-translational modifications that regulate the activity of a protein. Around a third of human proteins are believed to be phosphorylated, and so the kinases and phosphatases that mediate protein phosphorylation are of major interest to biomedical researchers. However detecting protein phosphorylation can be difficult, particularly from cell extracts. Phospho-specific…
Back in August I shared my training regimen for guesstimating the OD600 readings of microbial cultures with superhuman accuracy. Although my method is effective, I will admit that it has two shortcomings: you need to make a separate standard curve for each container type, and guesstimation is not an officially sanctioned scientific method. But now,…
If you use a human cell line in your research, have you wondered where, or who, it came from? I never gave it much thought, until I read Rebecca Skloot’s book, The Immortal Life of Henrietta Lacks. In 1951, cervical tumour cells were taken from Henrietta Lacks and put into culture, to divide endlessly and…
For a long time we’ve been able to pinpoint the subcellular location of proteins, and the advent of FISH (Fluorescence in situ Hybridization) allowed us to locate the position of genes in the nucleus, but recent advances in RNA FISH are making it easier and easier to collect the same data about individual messenger RNAs….
Previously, I introduced the DNA microarray technology and described the principle behind it: hybridization between the nucleic acid sequence from the biological samples being examined and a synthetic probe immobilized and spatially arrayed on a solid surface, the microarray. In this article, I will explain how these probes are designed and positioned on the array. I…
Do you want to immunoprecipitate (IP) a protein with a molecular weight that is anywhere near 55 kDa or 25 kDa? Then you have an irritating problem to deal with: antibody co-elution. But don’t panic, we have six strategies for dealing with your new problem. The Problem: Typically, the IP antibody is bound to Protein…
Working with RNA is definitely an acquired skill. It’s a lot more finicky than working with DNA, and requires careful attention to detail in order to avoid disastrous through RNase contamination. Here are a few common ways to lose your hard-earned RNA: 1. Don’t keep everything on ice Keeping the temperature of all of your reagents cool is…
Restriction enzymes are a basic tool in the molecular biologist’s arsenal. They’re super easy to use, and virtually essential for cloning and other applications. Restriction enzymes are also a great example of a perfect “tool” from nature that scientists have co-opted for their own use. Here are a few fun facts about restriction enzymes that…
I once knew a postdoc who was absurdly accurate at guessing the optical density of microbial cultures. I was jealous – imagine how much time I would save if I could spec my cultures just by looking at them! Since I lacked the innate optical talents required to compete with my friend, I developed a…
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