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Sample fixation for electron microscopy can be done using either chemical fixation or cryofixation. Discover the benefits and drawbacks of each of these methods.
Probing Nucleic Acid-Protein Interactions with EMSA The electrophoretic mobility shift assay (EMSA) is a powerful technique for detecting specific-binding of nucleic acid-protein complexes. Over the past 30 years, EMSA has been the “go to assay” to investigate the qualitative interactions between nucleic acids (DNA or RNA) and nucleic-acid binding proteins. Through the use of radio-labeled…
Alveolar epithelial cells (AECs) are one of the major types of lung cells that can be used to analyze the response of lung epithelia to external agents. AECs from mouse lungs can thus be utilized as an in vitro model of diseases. AECs are indispensable for studying lung development, injury, and repair. People working on…
Estimates indicate that there may be up to 2 billion living species of organisms, each with conserved and unique biological mechanisms that are vital for survival. How do scientists understand them all? Enter model organisms. Model organisms, as the name implies, are living things which are used as representative models for understanding other organisms. They…
For many decades, the only way to detect sepsis – bacterial growth in blood – was isolating the bacteria and growing bacterial colonies on a special medium. This was done by first spinning down the blood, which brought the blood cells and bacteria into the pellet. The pellet was spread on a blood agar plate…
Ultramicrotomy is the process by which a sample is cut into very thin slices or “sections”, usually for imaging by transmission electron microscopy (TEM) or relatively new techniques using scanning electron microscopy (See Array tomography in three-dimensional scanning electron microscopy for biology). This technique requires a bit of finesse, and this article will help you…
Have you ever been looking through a box of slides and found something that you want to image or look at later, or even show to one of your colleagues or supervisor? Finding that exact spot on the slide at a later date can prove to be difficult- using a marker pen on the coverslip…
Have you ever wished you could snag individual strands of DNA or RNA with a lasso? Or look at them one by one, figuring out exactly where they are or what they are doing? Fortunately, there are techniques that exist to label nucleic acids for their visualization and purification! Nucleic acids can be labeled at…
Drosophila melanogaster, otherwise known as the common fruit fly, is one of the oldest and most powerful model systems used in biology. Fruit flies are cheap to maintain, and have a shorter life cycle and higher fecundity than mammalian models. They also have extraordinary genetic tools with which to investigate many molecular and cellular questions….
Cleaning the lab is one of the hardest jobs because it’s dull and repetitive. However, nobody in their sound scientific mind would argue that this can be avoided. Dust accumulates bugs, bacteriophages, and RNAses that can stray into your experiment and ruin it. Old boxes piling up is a fire hazard. Anybody who refuses to…
Long before “Alexa” was a household name, Alexa dyes were an established series of fluorescent dyes. The inventor Richard Paul Haugland named the dyes after his son Alex. Originally a trademark of Molecular Probes, the Alexa family is now a part of Thermo Fisher Scientific. Alexa dyes are frequently used as labels in fluorescence microscopy,…
Tiny, furry, spinning around a wheel—few creatures are as endearing as the lab mouse. Trying to obtain reproductive success with them, however, can leave you spinning your own wheels. Why is it that what works so well for the animal facility staff, or experienced technician, seems to be beyond your reach? After all, mice have…
Radioactivity is still the most sensitive detection mechanism for many macromolecules and enzymatic activities. In graduate school, I performed countless radioactive kinase assays, watching the radioactive gamma 32P of ATP get transferred to my autophosphorylating receptor of interest, and then separating my protein from free hot ATP on a gel. The gel is dried, covered…
Studying immune cell activation allows scientists to understand the way the body mounts a response to a specific infection, autoimmune diseases, or cancer. This knowledge plays a direct role in developing more efficacious vaccines and therapies. When tasked with capturing information on immune cell activation, flow cytometry remains the gold standard due to its versatility,…
Anyone who has worked with microorganisms, be it bacteria or yeast, is familiar with subculturing – the act of transferring some cells from a previous culture to a fresh growth medium. You do it either to reset the growth phase of your culture or to increase the biomass for downstream experiments. But there’s more to…
One of the most powerful methods of modern cellular biology is creating and analyzing RNA libraries via RNA-sequencing (RNA-seq). This technique, also called whole transcriptome shotgun sequencing, gives you a snapshot of the transcriptome in question, and can be used to examine alternatively spliced transcripts, post-transcriptional modifications, and changes in gene expression, amongst other applications….
ELISA (Enzyme-Linked Immunosorbent Assay) is the heartbeat of many labs in the research world, owing to its simplicity and its ability to answer a very basic question: how much of protein/peptide/antibody is in my sample? More specifically, it can be used to answer such questions as: How much IgG is in the serum after I…
RNAseq libraries, also called whole transcriptome shotgun sequencing libraries, provide a snapshot of cellular processes. This allows the researcher to gain information regarding changes in transcriptome in response to environmental changes, during disease, or after a drug application. RNAseq libraries also allow for the detection of mRNA splicing variants and SNPs. RNAseq libraries have virtually…
If you plan to work with purified DNA in the lab, it’s likely that you will use a commercial DNA extraction kit to isolate and purify your DNA of interest. With so many types of kits available, it can be a major challenge to choose the best one to use when working with an unfamiliar…
Russell and Burch first described the ‘3Rs’ concept in 1959. It acknowledges that animals are a valuable resource through which great discoveries can be made, but it is up to you to use them ethically and judiciously. The ultimate benefit is that people and animals will be able to live longer, happier, healthier lives! So…
Making mutations in mammalian cell lines is becoming much easier, especially with advanced molecular engineering techniques such as CRISPR/Cas9, among others. However, after making a mutation, do you know if all of the cells contain the same mutation with the same expression profiles, and are therefore homogenous? If you have 100% transfection efficiency using a…
When you think about culturing bacteria or fungi in large quantities, you likely envision flasks shaking or maybe bioreactors filled to the brim with liquid media. But did you know that many bacteria and fungi can grow on solid carriers without being submerged in liquid? Enter solid state fermentation (SSF). In this article, I’ll introduce…
A lot of research experiments require the use of a eukaryotic host as opposed to E. coli due to its greater conformity and suitability in expressing eukaryotic proteins. This is the reason why yeast cells have gained importance as cloning and expression hosts. For protein expression studies to hybrid screens, many applications require insertion and…
Maybe you want to examine the entire transcriptome or maybe you want to investigate changes in expression from your favorite gene. You could do whole transcriptome sequencing or mRNA-seq. But which one is right for your project? From budget considerations to sample collection, let’s briefly look at both to see which might be best for your…
RNA-seq is based on next-generation sequencing (NGS) and allows for discovery, quantitation and profiling of RNA. The technique is quickly taking over a slightly older method of RNA microarrays to get a more complete picture of gene expression in a cell. Data generated by RNA-seq can illustrate variations in gene expression, identify single nucleotide polymorphisms…
Non-mammalian cells, including bacteria, fungi, and plant cells, have a cell wall that maintains the shape of the cell. These cell walls are particularly strong, due to their composition as they contain polymers that create a rigid sphere around the vulnerable cytoplasm contained inside the plasma membrane. In bacteria, the cell wall includes several layers…
You are thinking of trying out RNAscope®. After all, RNAscope® holds promise for increasing the sensitivity and specificity of your in situ hybridization. Yet, getting started can be a little overwhelming with the numerous kits and reagents available in the RNAscope product line. Here’s an overview of your options to help you navigate to the…
Multiplex ligation-dependent probe amplification (MLPA) is a molecular technique developed by MRC-Holland back in 2002. In a nutshell, MLPA is a sensitive technique that allows quantification of nucleic acid sequences, quickly and efficiently. It is performed in many laboratories worldwide, and can be applied to detect copy number changes (like deletions or duplications) of a…
Today, the gut microbiome is garnering a large amount of media attention for its role in human health and disease. From influencing immune responses to impact our brain, the gut microbiome is an important and necessary aspect of our life. So much so, that current investigations in the gut microbiome are focusing on developing biomarkers for…
The epigenome has been in the research spotlight, and for good reason. Not only has it been associated with the developmental stages of an organism, but epigenetic alterations lead to disorders and have been linked to many human diseases. So, the question stands: what exactly is an epigenome? What Is the Epigenome? Simply put, the…
For most molecular biology purposes, DNA is thought of as a string of nucleotides running from 3’ to 5’, and the corresponding mRNA sequence is complementary to this DNA string. However, visualizing this quirky DNA structure for what it is – two antiparallel strands joined together – it quite important for many applications, such as…
What Is Alternative Polyadenylation? Processing of mRNA and its regulation plays a fundamental role in gene expression. As science progresses, alternative polyadenylation takes center stage in the undercurrents of gene expression. 1,2 Polyadenylation is part of the pre-mRNA maturation process and involves polyadenylation of the 3’ end of the emerging RNA. This process happens to…
What Are Non-Coding RNAs? What was once considered “junk” may end up being the most important part of our genome. Non-coding RNA (ncRNA) is RNA that is transcribed from DNA but diverts from the “central dogma” because it does not code for proteins. NcRNAs are ubiquitous in eukaryotes: while 90 percent of eukaryotic genomes are…
One day, a colleague stopped by my workbench to ask which detergent would not break the nuclear membrane. Based on my previous experience using gentle detergents in lysis buffers, I replied, “NP-40”. However, we had two brands of NP-40. A closer look at the datasheets revealed that the chemical names were different even though they…
Commonly, no one thinks much about how the surfaces of labware (like microcentrifuge tubes, test tubes, dishes, etc.) can affect experimental results. We might know when we need to use glass versus plastic. Or we might know that certain chemicals, like chloroform, will interact with some plastic polymers, and you must use polymers that are…
There are many cloning methods that do not require restriction enzymes or ligases. Read below to learn about how to achieve seamless cloning results via Topoisomerase cloning, SLIC, and Gibson. Method #1: Topoisomerase Technology Topoisomerase technology requires no special primers and no ligases – it is as easy as cloning comes. This technology is based…
If you’ve ever worked with proteins in the lab, you probably know just how critical protein purity and quality are for downstream applications. In this article, we’ll review the multitude of problems that are encountered with ‘bad’ protein samples and how you can analyze the purity and integrity of your favorite protein prior to using…
There are a few different ways of approaching site-directed mutagenesis. Here, I’ll give you a quick introduction to inverse PCR and why it’s useful, as well as going through a full protocol for SDM using modified primers!
Over the past few decades molecular biologists have developed procedures to simplify and standardize cloning processes, allowing vast arrays of artificial DNA structures to be more easily assembled. Are you familiar with all the cloning options out there? Let’s look at five different cloning methods you can use to get your construct. At the end…
Ligation independent cloning (LIC) is an easy and effective method to ensure successful cloning, all without the need for ligation. As easy as the technique is, designing primers can be a bit tricky. In this article, we will present a quick overview on primer design for ligation independent cloning.
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