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So you’ve isolated your DNA or RNA from your favorite sample. And now, if you are anything like me, the first thing you’ll do is scramble to check the quality and concentration of your extract. You have a few different options at your disposal to perform this crucial analysis, which will let you know whether…
Ribonucleases (RNases). We’ve been giving them a hard time here lately. We’ve been talking about how they are the bane of the lives of researchers who work with RNA. And we’ve told you how to find their weaknesses and shown you a myriad of weapons that you can use to kick their RNase butts. But…
If you want a more efficient, cheaper way to do bacterial transformation, you are definitely going to like this article.
RNases are like the baddie super-heroes amongst laboratory enzymes. They are omnipotent, destructive and seemingly indestructible. This is because they were created by evil overlords, for the sole purpose making life difficult for the brave scientists who battle every day to produce high quality, intact RNA preps. Ok, I’m joking about the overlords part. But…
MicroRNAs (miRNA) are short, non-coding RNAs involved in post-transcriptional silencing of gene expression. miRNAs can be associated with exosomes and can function as cancer-specific biomarkers. This, coupled with the fact that they are stable in plasma and serum makes them valuable diagnostic tools, as long as they can be reliably isolated from the serum and…
In my last article, I explained that plasmid DNA recovered from a plasmid prep consists of few different species; supercoiled, nicked, linear and single stranded circular, and how you can distinguish them on a gel. Supercoiled DNA is the desired form of plasmid DNA; it performs better in downstream applications such as automated sequencing and…
Alternative splicing is a highly orchestrated process that uses a multitude of regulatory mechanisms. Splicing specificity involves a precise interaction between cis- and trans-acting regulatory elements, and factors that disrupt these interactions can result in aberrant splicing. There are multiple ways in which mutations can affect splicing fidelity: A point mutation in the cis-acting splice…
The Basic Local Alignment Search Tool (BLAST) algorithm is at the heart of a free suite of online resources available through the National Center for Biotechnology Information (NCBI). While most researchers are aware of BLAST as a sequence alignment tool, NCBI’s BLAST suite offers so much more! I’ll cover in-depth how to use these resources…
Alternative splicing events often occur in a spatiotemporal manner, and some are regulated by alternative splicing regulators, with striking variation across tissue types and developmental stages. Alternative splicing events are often differentially regulated across tissues and during development, as well as among individuals and populations, suggesting that individual isoforms may serve specific spatial or temporal…
Parents of small children attending nursery know that the period of time from September to June is a succession of colds and flues for the whole family – children with their underdeveloped immune system exchange viruses, creating new potent strains. Well, that’s probably how bacteria feel all the time in the natural environment teeming with…
The stability of an antibiotic depends on its chemical structure, method of isolation (from natural sources or chemical synthesis), and the mechanisms of inactivation. First generation antibiotics isolated from natural sources, such as penicillin, are the most unstable, followed by its semisynthetic derivatives (such as ampicillin and carboxycylin). Aminoglycosides (kanamicin, spectinomycin, etc.) are more stable….
We’ve all been there. Digging through the -80°C freezer, fingers about to get frostbite as you scrape the ice off a tube to read an illegible plasmid name, hoping it’s the right plasmid with little or no knowledge of how it was cloned in the first place. And this is the starting material for your…
Plasmids—the loops of DNA in bacteria that form the original foundation of biotechnology—were being discovered constantly in the 1940s and 1950s. The only problem was, they were called everything but. Series of scientists found bacteriophages and other strange loops of somatic DNA, and gave them a series of names, including: pangenes, bioblasts, plasmagenes, plastogenes, choncriogenes,…
Visualization of DNA in gels is one of the most common procedures a molecular biologist can perform. In a good day, I can run at least 4 different DNA gels! When I was trained, ethidium bromide (EtBr) was the only viable option to easily visualize small amounts of electrophoresed DNA. However, safer and more sensitive…
Whether you’re employing sequencing gels, Sanger-based methods, or the latest in pyrosequencing or ion torrent technologies, obtaining, manipulating and analyzing your sequences has never been easier. Depending on what your goals are, you need to understand the pros and cons of the software. There is a lot of software out there, so do you your…
Fortunately, those of us who have learned how to sequence know that aligning sequences is a lot easier and less time consuming than creating them. Whether you’re employing sequencing gels, Sanger-based methods, or the latest in pyrosequencing or ion torrent technologies, obtaining, manipulating and analyzing your sequences has never been easier. We’re going to take…
If you have ever worked with RNA, you know about DEPC (diethylpyrocarbonate). You add it to water at a concentration of 0.1%, shake or stir, incubate at 37°C for two hours or at room temperature overnight and, as if targeted by a magic bullet, the RNAses that may have been in the water are gone….
Collecting biological samples in the field can be difficult, since storage conditions outside of the lab are often less than optimal. Enter the Whatman FTA (Flinders Technology Associates) Cards. The Whatman FTA Card, a filter paper product manufactured by GE Health Care, is a paper matrix laced with a proprietary mixture of chemicals that lyse…
Here, we share a protocol for a midiprep, which, if not faster, gives a larger plasmid DNA yield than any commercial midiprep kit.
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…
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:
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: Gene function and cellular processes Gene regulation and interactions Gene expression levels in different cell types and how this expression is altered by the addition of various compounds or disease…
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…
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.
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…
Site-directed mutagenesis studies can be extremely useful for elucidating the function of a gene or protein, or for creating variants of an enzyme with new and improved functions. There are now many approaches available for generating site-directed mutants, whatever your purpose. In this post I’ll summarize three techniques that will enable you to produce a…
Here’s an all-too-often repeated scene in the lab: First thing in the morning, you approach the 37°C incubator with trepidation, open it and through one half-open eye you take a look at the LB plate that you spread your ligation-reaction-transformed E.coli aliquot onto. Looks good – thousands of colonies. Emboldened, you take your “no ligation…
A partial digest – typically done when you only want to cut one of two or more restriction sites in a DNA – can be a frustrating procedure to execute. The best advice anybody can give about partial digests is to avoid having to do them. However, there are times when there just aren’t many…
I learned most of my molecular biology skills in the first lab I worked in almost 10 years ago. I realized recently that I was in desperate need of a refresher course, so I did a little bit of reading to see if I could improve the efficiency of my cloning reactions. In the process,…
CIP has been around for a while, but there is a better alternative.
We recently featured an article about how to streamline your cloning. But what about those days when you have too much on your plate, and need to put some things off until later? Here are a few hints on where you can pause in your cloning experiments while working on other projects: Restriction digests can…
I always keep an ear open for helpful tips in the lab – those little tricks that can make your experiments faster, easier and better. Here are a few tricks I’ve picked up for trimming down the time it takes to do your cloning: Restriction digests Many digests are complete within 10 minutes of digestion…
We received the following question from Bitesize Bio reader, Beheroze Sattha. It relates to a problem with absolute quantification using plasmids for standard curves. Since many people use this technique it is an interesting one question for us to explore, and it also gives us a great opportunity to cover some important tips for performing…
If you’re performing DNA/RNA precipitations, you will have read Suzanne’s excellent article on which alcohol to use for precipitating your precious samples (check out some useful info in the comments for that article as well). Its publication prompted the recall of a useful tip I learned from a post-doc many years ago, one of those…
There’s something in the water, and it would love to go after your experiments. Straight out of the tap, water contains microorganisms, endotoxins, DNase and RNase, salts and other impurities that could gobble up your experiment in one bite. Of course we avoid this drama completely by using purified water from which these nasties have…
Working at a plasmid repository, I get a lot of feedback from scientists who are relieved we exist simply because that means they don’t have to request a plasmid directly from another academic lab. Either they’ve had a bad experience making requests in the past, or they really don’t know how to go about doing…
TAE or TBE, which is best? Well, of course, it depends on what you want to do. Here are the pros and cons of both: But you might be better of using neither of these buffers. Despite the fact that they have been firmly established as the most popular buffers for DNA electrophoresis since their…
It’s the molecular biologist’s version of ‘I have good news. . and bad news’. The good news is that I amplified the DNA band of interest. The bad news is that I amplified these other bands as well! Oh, and this smear. What to do? Typically you might try and cut out the band of…
So you have some blood stored in the -20C or -80C and you want to isolate RNA from the samples. If you wanted DNA, you would have many products to choose from. But for RNA, your choices are more limited. Obtaining RNA From Frozen Blood is Difficult Why is that? The reason is that most RNA from…
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