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We all know the impact fluorescent proteins have had in advancing cell biology. Although fluorescent proteins have revolutionized the field, they aren’t perfect and like all things research, they have their limitations. If you’re looking for a genetic tool with superior fluorescent properties, or one that allows you to introduce a variety of labels into…
In part 1, ‘iPOND: Fishing for Proteins with DNA as Bait’ we went on a fishing expedition and learned how the iPOND technique can help us investigate the protein landscape of DNA synthesis. In this article, we will pit iPOND against a few other widely used techniques in order to answer the question: ‘Why should…
I’m a simple molecular biologist. It’s awesome how computational biologists use math to reduce and rebuild biological phenomenon. In my own way, I also like to reduce my observations to numbers. As a budding biochemist, I need to assemble and quantify the players in my pathway to truly understand it. In particular, I am interested…
Simple BLAST searching is pretty straightforward to many of us. Just plug in your sequence, select the species genome, and hit search! But have you ever wondered what it takes to run a BLAST query using these mammoth-sized (no pun intended!) sequence databases? BLAST searching can produce dozens, hundreds, or even thousands of candidate alignments….
Even though our knowledge about genomes grows daily, and in huge leaps, we sometimes need to remind ourselves that DNA was first isolated in 1869 and its molecular structure was only identified in 1953. The PCR reaction only hit the scientific community as recently as 1983! So even though we are growing fast, we are…
For all of you who have never heard of exosomes: You are missing out on a whole new paradigm in cell-to-cell communication. Exosomes are tiny extracellular vesicles that arise from fusion of the plasma membrane with specific endosomal compartments called multivesicular bodies. Most cells types make exosomes, and release them in order to communicate with…
What do water pipe slime, dental plaque, and persistent contact lens case contamination have in common? All are the result of biofilms! Biofilms are aggregates of microbes that adhere to surfaces using secreted matrices. Although relatively under explored, this fascinating phenomenon plays a critical role in some of the biggest challenges currently facing medicine, ranging…
There are two types of electron microscopy—transmission electron microscopy (TEM) and scanning electron microscopy (SEM). SEM creates fascinating 2D images by bouncing electrons off the surface of the sample. I highly recommend searching for SEM samples on Google images. There are a wide variety of applications for electron microscopy. While SEM images are aesthetically amazing,…
Every man, woman, and dog is doing quantitative real time reverse transcriptase PCR (qRT-rtPCR) these days. It’s a great method to measure your favorite transcript’s expression levels. One of the big plusses (like the Swiss flag!) of quantitative PCR in general is its high sensitivity. In principle, it can detect and quantify one molecule of…
Whether you work with human cell lines or microbes, their growth is governed by the same principles. I invite you to learn about something that lies at the base of any work with cell culture, whether cells have circular or linear chromosomes: the S-curve of the population growth. The length of each phase depends on…
Allele-specific expression can occur for various biological reasons, such as gene imprinting, or differential transcription caused by mutations, or single nucleotide polymorphisms (SNPs), or epigenetic alterations. Traditional end-point RT-PCR or qRT-PCR-based methods only detect overall levels of mRNA expression from a given gene rather than mRNA transcripts originating from individuals. If your project requires more…
No, iPOND is not a sleek electronic fishing device from Apple. However, if you thought about fishing, well, you’re not far off the mark. If you find yourself wondering which proteins are present at DNA during or after replication, iPOND is an elegant technique to help you find out. In this article, I will explain…
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…
Yeasts, such as Saccharomyces cerevisiae, Schizosaccharomyces pombe and Pichia pastoris, are routinely used in biology research labs around the world. Yeasts are easy-to-culture, unicellular eukaryotes, and make excellent model organisms because of the similarity of their genes and proteins with those of their mammalian counterparts. Yeast cells are used to study gene function, protein interactions,…
Immunolabeling is the tried-and-true immunochemistry method of getting the stain you want onto the molecular target you want. Whether that target is contained within a large region of tissue (immunohistochemistry) or inside a single cell (immunocytochemistry), the ability to accurately label large numbers of samples will simplify your workflow and help you to achieve excellent…
The first time I did a transformation was when I worked with site directed mutagenesis. I cloned a protein sequence into the p15TVL vector, created my mutants (but that’s another story), and was finally ready for the next step: transformation and expression of my desired protein. Little did I know that my enthusiasm would fall…
Enzymes are special among proteins. It is not enough to detect them. You need to know their activity level. If you have devoted a substantial part of your research to studying proteases, like I did, you’ll know how crucial it is to choose an appropriate enzyme assay. There’s a heap of lab techniques out there…
Imagine directly creating a mutation at (almost) any site in your target genome instead of screening thousands or millions of random mutants! The CRISPR/Cas9 system does just that. In its traditional form, this forward genetics approach takes 7 steps from start to mutated genome. However, there is a way to obtain your designer genome in…
Continuing from our first article on lasers for confocal microscopy, we will now discuss two specialized types of lasers: lasers for two-photon excitation and tunable, white light lasers. We will also discuss the applications of the two lasers. Lasers for Two-Photon Excitation The two-photon absorption phenomenon was first described for microscopy in 1931. Here, the…
Before we go any further, we have to get some things straightened out: RT-PCR versus qPCR versus RT-qPCR. Sooo confusing, amirite?? They all refer to specific molecular biology assays, but the names are unfortunately used interchangeably, which can be awfully confusing for just about anyone. So without further ado: RT-PCR is short for reverse-transcriptase PCR,…
I am sure many of you have been there. Everything is going smoothly, and your project seems to be working out perfectly. And then there is this one PCR. For some reason, it just won’t work. It is a black dot on your record. Even though I have a scientific mind, I have to be…
In its simplest form, a bacterial growth medium is designed to support the growth of bacteria. Depending on which bacteria you want to culture, you may have a range of different media to choose from, each containing a rather unique blend of sometimes surprising (and odd!) components! In this article, I will take you through…
When I first told a lab colleague I was going to be doing phage work in a lab that had otherwise only dealt with bacteria, I was met with expressions of awe, and then fear. Being that a bacteriophage is essentially a predator of bacteria, this reaction is legitimate for a bacteria-loving scientist. Also, we…
In the first part of this series, we discussed the differences between a color and a monochrome microscope camera and when one is advantageous over the other. We also touched on the subject of optimal camera resolution for a given imaging system. In this part, we will tackle a few additional camera specifications and how…
Here is a rundown of our top features to look out for when you are shopping for a new PCR instrument.
The development of new drugs requires reliable and robust animal disease models. Since the cause of many diseases is still unknown, it is often difficult to identify adequate and predictive disease models. For example, researchers developing treatments for neuropsychiatric diseases such as Parkinson’s and Alzheimer’s face a particular challenge given the subjectivity of many of…
In my previous article I discussed steps you can implement to ensure that a sample is ready for cell sorting. But now it’s time to make sure the sort worked. Here are a few sorting checks and measures to ensure that all’s well that ends well. Post-sorting Checks and Measures Re-evaluate Your Catch Tubes Sorting…
The first thing one might notice when working with metallo-proteins is that they offer unique, colorful reactions. These colorful reactions are based not only on the metal, but the ligand, or coordinating molecules. Approximately 80% of proteins contain inorganic cofactors like iron (Fe) and copper (Cu) metals necessary to catalyze a reaction. Understanding how these…
The use of restriction enzymes to characterize DNA has been popular since the 1970s. Today, this “old school” technique is still one of the easiest and fastest ways to assess DNA sequences. Like most lab reagents, restriction enzymes can be fickle and you should bear a few things in mind when using them. Generally, sticky-ended enzymes have greater…
Mammalian cell culture techniques are not something you learn from a book, per se. And because of this, it is important to be properly trained, especially in sterile techniques. It is important to keep your cell lines from contamination and just as important to keep yourself safe. Nevertheless, people tend to do things a little…
From Alkaline phosphatase to Warthin-Starry, we take you through the various histology stains available.
Next generation sequencing opened the doors to our genome. It gives massive amounts of information in a week – whereas Sanger sequencing takes thrice as long, and causes lab lesions due to the abusive use of pipettes. Indeed, with minimal hands-on procedures we obtain a lot of data. But nothing in Science is ever easy….
Rapid genomic analysis offered by next generation sequencing (NGS) is ideal for personalized medicine approaches to clinical genetics, microbiological profiling, and diagnostic oncology. Many standard clinical samples are preserved as formalin-fixed, paraffin-embedded (FFPE) tissues, which presents obstacles for use in NGS analysis. FFPE tissue preservation has the benefit of keeping samples intact for histological examination…
Construction of high-quality sequencing libraries is pivotal to successful NGS, and DNA quality is one of the most critical aspects of library preparation. As this Nature Methods paper illustrates, DNA shearing involves appropriate and consistent fragment sizes for sensitive and accurate sequencing, and the fragments must be accurately analyzed prior to sequencing to measure molarity…
Bacteria are the workhorses of many molecular biology laboratories, and mastering the basic techniques to manipulate bacteria is an important stepping-stone towards achieving great results. When isolating DNA from bacteria, it is important to start with a single colony to ensure a homogenous population of bacteria in your culture. Isolating a single bacterial colony from…
The intriguing thing about protein expression is that the combination of transfer RNAs (tRNAs) that translate the 3 letter codon into an amino acid (aa) far exceeds the number of existing amino acids (aa). If you do the math correctly, the maximum number of unique combinations using the triplet code to code for the 4…
When you are a newbie to qPCR or qRT-PCR, it is quite common to write everything down in your lab notebook and then tediously mark off reagents or samples as you add them. People typically start with a master mix for items you add to multiple samples such as (Mg2+, dNTPs, 10X PCR buffer, additives,…
Most of us are aware of genetic engineering systems like Cre-Lox, TALENs, Zinc finger systems, and of course, CRISPR-Cas9. These are all examples of CSSR- Conservative Site-Specific Recombination. We use these site specific recombinases routinely, but do we really know about them or what the future hold for these tools? It turns out that CSSR…
If you are a plant biologist and working with the model plant Arabidopsis thaliana, undoubtedly you are a great fan of The Arabidopsis Information Resource (TAIR). You also probably order seeds/materials from the Arabidopsis Biological Resource Center (ABRC), or request them from fellow scientists. Of course, seeds are one of the basic materials you…
The unique feature of real-time quantitative polymerase chain reaction (RT-qPCR) is that it associates the amplification of your target gene with a fluorescent signal in a quantifiable manner. Presently, there are numerous fluorescent tool kits/methods to consider when designing your RT-qPCR experiment. However, the two major categories to choose from are fluorescent intercalating dyes and…
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