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Surface Plasmon Resonance (SPR) is the gold standard for measuring biomolecular binding without the need for labeling (i.e., label free detection of kinetics). SPR is especially valuable because it doesn’t just provide information at the start and end of a binding event, but can be used to follow association and dissociation kinetics of biomolecules in real-time….
If you’ve been keeping up with our recent series of articles, welcome back! If not, you can catch up on how fluorescence works or what not to do with your flow experiment. In short, we have been discussing fluorescent labels and their role in flow cytometry. Today, I’ll round out our discussion by touching on…
When I was being trained in microbiology as an undergrad, one of the first skills I acquired was the ability to quickly compare and visualize amino acid sequences using BLAST and ClustalW. 15 years later, those two programs have done nothing but improve by expanding the data contained in these databases and simplifying the user…
Whatever molecular biology techniques you use, at some point you will have to clean up your DNA samples to remove things like buffers, contaminants and nucleotides from you precious sample, so that you have perfectly pure DNA for your downstream experiments. Magnetic beads are one DNA cleanup option. They are simple and effective—and their reassuringly…
Image analysis can be biased. Discover the three main steps to image quantification and learn how to quantify images in an unbiased way.
The only constant with microscopy imaging is variability in both color and image quality. You only need to look at images in journal articles, posters, around your laboratory, or compare your images with a colleague’s—the evidence is staggering. Interestingly, variability doesn’t generally come from the digital camera, rather it comes from our use of imaging…
In the midst of all the cool new sequencing techniques and technologies out there today, you may have overlooked the tried and true method of Shotgun Sequencing. What is Shotgun Sequencing Anyway? Shotgun sequencing gets its name from the concept that a large sequence is essentially broken up in to many, many smaller pieces, similar…
In my last article, I discussed how to best keep your lab’s HPLC running smoothly. However, even the best-maintained HPLCs and columns need periodic cleaning. Today, I’ll describe how to identify and troubleshoot a clogged HPLC column. Columns ARE Finite First of all, it’s important to realize that columns do have a finite lifetime. The…
Flow cytometry. Some people love it—most hate it—but all can agree that it is one of the most powerful analytical tools immunologists possess. Here’s a quick refresher: as the name suggests, flow cytometry measures the physical and chemical characteristics of cells. This is accomplished by fluorescently labeling cell surface markers/proteins using antibodies conjugated to fluorophores….
You can create stably transformed plants expressing your gene of interest; be it for the subcellular localization of your protein or simply for the in planta protein expression and purification. Whatever it is, you can do wonders with plant transformation. Sound difficult? It isn’t. Just like there are millions of microbes that interact with us,…
If you work in the field of molecular biology, there is hardly a day that goes by that you don’t use nucleotides. But beyond the use of the four well-known deoxynucleotides in PCR, you can use nucleotides for several other applications. For example, kinases and phosphatases use nucleotides as substrates, and phosphotransferases transfer phosphate group…
Like all technical fields, molecular biology contains a very robust “theoretical” realm and an equally robust “practical” realm. Unfortunately, these two existences don’t seem to overlap as often as we’d like. Consider, for example, a simple Western blot. While an antibody interacting with its target on a membrane seems pretty straightforward, there are numerous other…
At the heart of cloning are restriction enzymes. Restriction enzymes are a common tool in any molecular biology lab. Need to know how large your plasmid is? Cut it with a restriction enzyme. Need to chop your genomic DNA into smaller pieces for a southern hybridization or to prepare a library? Use a restriction enzyme….
DNA shuffling uses PCR technology in a very creative way. It allows you modify your protein to make a new protein you want. You can evolve proteins in microcentrifuge tubes on your very own lab bench. Isn’t that fantastic? DNA shuffling is also a very powerful technique for directed molecular evolution. W. Stemmer first used…
You have probably run a standard agarose gel hundreds of times. They are great for visualizing small DNA fragments up to 10 kb, but what if you want to examine really large pieces of DNA or even whole chromosomes? This is where pulsed field gel electrophoresis (PFGE) comes in! While the equipment required to run…
As science is becoming more interdisciplinary, the tools we use to answer questions are also crossing party lines. Case in point: flow cytometry. Once a tool only used by “real” immunologists, flow cytometry is fast becoming a method by which numerous questions can be answered, from the length of a cell’s telomeres, to the state…
If you’re anything like me, your biggest lab fear is working with expensive equipment prone to damage. HPLC is a wonderful tool, capable of separating, identifying, and quantifying a vast array of compounds, but it requires an attentive scientist to properly handle and maintain each component. In this article I’ll describe a few basic handling…
The enemy of my enemy is my friend –Ancient Sanskrit proverb Luna, 20 July 1969. Neil Armstrong set his foot in another world for the first and only time in human history. But this is not a story about space exploration; it is a story about the vehicle they used to do it—the Lunar Module…
Speed up your SDS-PAGE with our time-saving tips and tricks!
Phosphorylation Equals Cell Signaling! How do cells communicate and respond to their environmental cues? This question has been on the hot list for scientists ever since the discovery of the cell. Cells use signaling cascades based on biochemical reactions to deliver or receive messages. How cool is that? The major secret of cell signaling was…
How do you pick which antibody you should use in your assay? If you’re starting a new assay and need an antibody for the job, then selecting a new antibody from the plethora available could be high up on your to-do list.
Restriction cloning, at its core, is quite simple. You simply cut the target vector and insert with the same enzymes, clean digested vector and insert up, ligate the two together, transform the ligated vector and insert into bacteria, and then screen. While getting each of the steps correct can be a bit of a hassle,…
An essential step in mouse breeding is genotyping them to determine the genotype of every mouse in the litter. It is also useful to differentiate between various groups of experimental mice if any confusion arises. When genotyping, you will be hunting for the specific gene that you want your mice to have or a genetic…
Scanning electron microscopy (SEM) is a powerful technique, traditionally used for imaging the surface of cells, tissues and whole multicellular organisms (see An Introduction to Electron Microscopy for Biologists)(Fig. 1). While the resultant images appear to be three dimensional (3D), they actually contain no depth information. However, there are several SEM techniques that can obtain…
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…
Cloning, purifying, and expressing modified genetic material is routinely done in microbes such as Escherichia coli (E.coli). Relatives of this molecular biology workhorse normally live in the intestinal track of humans. The particular E. coli strain (K-12) that scientists use all over the world was isolated from the feces of a diphtheria patient in 1922.1…
Every biochemist is familiar with proteases. More often than not, proteases cause a lot of anxiety. To this end, a lot of research has been done in developing techniques to prevent the activity of proteases. But some of these proteases can be the good guys too! For example, you can use them to separate your…
Kary Mullis invented polymerase chain reaction (PCR) in 1985 creating a revolution in molecular biology techniques. But it hasn’t stopped there. PCR has greatly evolved over the years. Today, we stand at a point, where we can clone micro RNAs (miRNAs) in real time! Due to miRNA size (about 18-21 nucleotides long) and varied expression levels,…
Fourier Transform Infrared spectroscopy (FTIR spectroscopy) is a useful and exquisitely sensitive technique used to identify and quantify unknown compounds, as well as study fine molecular details. However, to obtain a meaningful IR spectrum, it is not only important to prepare the sample correctly but also to learn how to clean the apparatus that houses…
SAGE, or serial analysis of gene expression, is a technique that enables you to digitally analyze the entire gene expression profile of a cell(s). Before this technique, scientists were limited to studying a few gene’s expression at once by a technique called the expressed sequence tag approach. The coolest part of SAGE is you don’t…
Sonication is mostly used during preparation of protein extracts to help break apart the cell. Although most lysis buffers have buckets of detergent that lyse cell membranes, sonication just gives an extra hand in breaking everything apart. Sonication also breaks up, or shears, DNA in a sample—preventing it from interfering with further sample preparation. Have…
Some techniques can sound very dry but this isn’t one of them! SAGE was first described and published by Velculescu et al. in 1995. At the time, techniques like RNA blotting and expressed sequence tagging were used to study gene expression. However techniques like these were slow and very limited. The speed of SAGE and…
Over the last few decades, PCR, next-generation sequencing, and microarray technologies have taken blood-based research to a new level. Modern blood-based applications range from DNA fingerprinting, whole genome sequencing, blood banking to liquid biopsy, and many more. Regardless of the application, pure, intact, double-stranded stranded, and highly concentrated DNA extraction from whole blood is an…
When you perform genomic DNA extraction from whole blood, low yield or low quality DNA can result in many issues. No matter your intended downstream application—qPCR, next generation sequencing, Sanger sequencing, and so on—you need high quality DNA. We’ve made this step-by-step guide to assist you in getting the highest possible DNA yield and quality, and…
There is a growing trend in using microalgae as the expression system for heterologous proteins. However, I find most protocols dealing with microalgae available online are not that great or informative! So I would like to share my experience in using Chlamydomonas reinhardtii as the model microorganism. Before you start expressing your protein, you need…
In the 30 odd years since its invention, the polymerase chain reaction (PCR) has become the bread and butter technique of molecular biologists. The secret to its indispensability lies in its simplicity and versatility. Numerous variants of the technique have been developed; one of these, real-time PCR, has become the method of choice for quantitative…
Do you use pre-packed Superdex 75 or Superdex 200 columns for gel filtration chromatography? Ever wonder if other media could better address your purification needs? Look no further. Your quest ends here! But if you’re looking for information on gel filtration principles, check out this earlier article. Choosing a Column for your Gel Filtration Experiment…
Do you use biotinylated secondary antibodies in your immunohistochemistry? You could use polymers instead. They are a great time-saving reagent.
Two years ago, all I knew was third BASE in my baseball field and the cutter ball from the pitcher. Now, I know a lot more about lab-based BASES and cutters: REBASE and NEBcutter. While they sound like baseball terms, REBASE and NEBcutter are tools for working with restriction enzymes. Read on to find out…
Mice are an extremely powerful research tool, but they do take extra time and effort. While you can purchase mice from vendors like Jackson Labs or outsource your genetic engineering to a number of companies, it’s often necessary, and more economical, to start a breeding colony. Even if you get your mice commercially, you’ll probably…
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