Dr Rebecca Tirabassi's Profile

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6 ways to show your plasmid preps some TLC and get more supercoiled plasmid in return

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 […]

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Outgrown the Roost: A Quick Protocol for Passaging Adherent Cells

Your cells have dutifully “sat down”, stuck to the bottom of the dish and replicated, replicated, replicated. You see a swarm of cells that have reached confluency and filled the entire plate. It is time to split them. This can be a relatively easy ritual, but missteps can lead to dead floating cells and the […]

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In Cells and Model Organisms 23rd of January, 2013
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Outgrown the Roost: Passaging Adherent Cells, the Basic Process

Splitting, passaging, subculturing… whatever you call it, while the specifics of passaging adherent cells will depend upon the individual cell type, the basic process involves four simple steps. These basic steps are outlined below while a sample quick protocol can be found here. Rinse Cells With a Balanced Salt Solution (BSS) Prior to detaching cells […]

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In Cells and Model Organisms 16th of January, 2013
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Tips for Choosing and Using a New Primary Antibody

Finding a good commercial primary antibody can often feel like playing Russian roulette.  Nothing is more disappointing than buying a $300 antibody that doesn’t work for your use.  There are some steps you can take, however, to increase your likelihood of success. Scout out other labs.  Before you buy, ask if anyone around you or […]

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How to Calculate a DNA Primer Concentration

Calculations can be the bane of laboratory work.  Therefore, I have always looked for easy methods for getting the math done. Here are several different ways to calculate primer concentration depending on the starting material.  For all calculations, let’s assume we have 22 nmol of a DNA primer containing 16 bases. From lyophilized powder Primers […]

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How Do YOU Stain Your DNA?

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 […]

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Quick Protocol: How to Work Safely and Effectively with a Biological Safety Cabinet / Culture Hood

Before using any Biological Safety Cabinet (BSC) for the first time, have a person with working knowledge of the machine give you an overview of how to use the cabinet. Different labs have different protocols in regards to running the cabinet, disinfecting the cabinet, determining which pathogens that may be used in the cabinet and […]

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3 Ways to Abuse Biological Safety Cabinets

As we learned in my previous article, cell culture hoods have many names. As if that wasn’t enough, they are all-too-often misunderstood and mistreated, which can lead to dangerous situations harmful for both the worker and the general lab environment. Here are three common ways that workers abuse biological safety cabinets; make sure you don’t […]

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Biological Safety Cabinets and Culture Hoods: Know The Difference

Biological safety cabinets, laminar flow hoods, clean hoods and culture hoods are all common names for those essential pieces of equipment that you use in cell culturing. The terms are used inter-changeably, but in fact there are lots of different types of culture hoods, each of which does a different job. Knowing which is which […]

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How to to Speed up Commercial Midi and Maxi Plasmid Preps

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 […]

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