Genetic Industries By Alexis Mayberry

What is Gel Electrophoresis? Electrophoresis is any process that uses electricity to separate the particles in a fluid. In gel electrophoresis, this fluid is a gel with the specific properties needed for a particular sample. Purpose: Gel electrophoresis is a technique typically used to separate deoxyribonucleic acid (DNA) molecules in a sample. It usually analyzes the sample, but it can also prepare the sample for another analytical technique. Gel Selection: The specific gel used depends on the weight and composition of the molecules in the sample. For example, the gel used for small DNA molecules is a mesh of polyacrylamide.

Historical Background Gel electrophoresis was first introduced in the 1930s. During the 1960s and 1970s, most of the techniques for separating DNA and proteins were developed. The gel electrophoresis technique is developed by Joe Sambrook, Phil Sharp and Bill Sugden. They used agarose gel electrophoresis to separate DNA fragments.

Electrophoresis Process STEP ONE: Create the gel using agar. Mix the agar together with water and dissolve the agar by heating it. STEP TWO: Insert the electrophoresis comb into the gel mold. The comb will create the wells where the DNA is placed. STEP THREE: Draw a small diagram of the gel and label which sample will go into each well. STEP FOUR: Remove the comb and load the samples of DNA using a pipette. Load each sample of DNA into each well. STEP FIVE: Put the electrophoresis lid on the chamber. Turn on the power source making sure the voltage is between 50 and 100 volts. Let the gel for approximately 30 minutes. You will see the samples separating as they run through the gel. STEP SIX: Turn off the power source and remove the electrophoresis lid. Remove the gel and place it in an ultraviolet light box, also known as the transilluminator. After doing this, you can see the different DNA bands.

Current Uses of the Gel Electrophoresis Microbiologists use gel electrophoresis on a regular basis. The process allows them to separate and organize DNA and RNA by size, thus making it easier to study them at the molecular level. In the world of forensics, gel electrophoresis is used to obtain a DNA fingerprint of a criminal. This means that scientists can accurately tell whether two pieces of DNA, one found at a crime scene and one belonging to a suspect, are matches. Gel electrophoresis not only provides geneticists with a clearer picture of DNA, it also helps prepare DNA for cloning and genetic engineering. Since microbiology is centered around the study of organisms at the tiniest levels, gel electrophoresis is helpful in pulling information out about these organisms. Virology, a subset of microbiology, also uses the process to help diagnose different strains of viruses. Biochemists work with cellular components, particularly proteins and nucleic acids. These components may also be mapped out using gel electrophoresis.

One Common DNA Profiling Method The analysis of small nucleotide repeats known as Short Tandem Repeats (STRs). STRs are short sequences of DNA (3 to 7 nucleotides) that repeat themselves in regions of up to 400 nucleotides. The greater the number of repeats in a region, the longer the piece of DNA. A technique called gel electrophoresis is used to separate out pieces of DNA of different sizes. Combinations of different STRs (there are hundreds of types) can discriminate between individuals. US forensic scientists generally use a standard set of 13 STRs.

Advantages Detection Limits Based on Size: Most DNA, RNA and proteins can be detected using gel electrophoresis, regardless of size. The concentration of the gel matrix is chosen beforehand to easily separate the molecule of interest based on the estimated size. Starting Material: A large amount of starting material is not needed for gel electrophoresis. For example, picograms of DNA can be detected using electrophoresis.

Disadvantages Difficult to Extract Samples: Once a sample has been run on a gel, it is possible to extract the sample from the gel for further analysis. However, it is nearly impossible to obtain all of the material in the original sample. Harmful Materials: Care must be taken when handling materials used in gel electrophoresis. For example, ethidium bromide is commonly used in DNA gel electrophoresis, and is a known mutagen.

Better understanding of how Gel Electrophoresis works http://youtu.be/3i-DxJ3oJzE

Report Details Causes of Salmonella Outbreaks at Two Arkansas Prisons News Article Report Details Causes of Salmonella Outbreaks at Two Arkansas Prisons The Arkansas Department of Health and the U.S. Centers for Disease Control and Prevention report that 597 inmates were put in prison at and were infected with eight serotypes of Salmonella during the outbreak. Those eight strains of Salmonella revealed 15 pulsed-field gel electrophoresis (PFGE) patterns of the bacterium. This finding surpasses all previous reports for multiple-serotype outbreaks of Salmonella previously reported in prisons. Case-control studies conducted at the prisons revealed that the Salmonella outbreak was statistically associated with chicken salad and other food items. Chicken salad was the likely cause of the outbreak at Prison A. Multiple food items, as well as person-to-person transmission, were the likely causes of the outbreak at Prison B. Both prisons incorporated eggs produced at Prison B into the chicken salad dishes served at the institutions. Several food-handling errors, including leaving chicken salad at unsafe temperatures, could have contributed to the Salmonella outbreak. The editors further state that sanitarians should regularly inspect prison kitchens, cafeterias, and agricultural facilities, and require them to maintain standards equivalent to those of commercial establishments in accordance with state or local guidelines.

References http://www.theage.com.au/news/education-news/prime- evidence/2006/08/25/1156012746544.html?page=fullpage http://www.foodsafetynews.com/2014/03/arkansas-prison-salmonella- outbreaks-detailed-in-new-report/#.UzzGFn-9KSP http://artforscience.com/artforscience/Books.html http://www.uni-kiel.de/landscapes/allgemein/news_detail/20130827- adna_pigs.shtml http://en.wikipedia.org/wiki/Gel_electrophoresis http://www.dnalc.org/resources/animations/gelelectrophoresis.html http://www.nature.com/scitable/definition/gel-electrophoresis-286 http://www.ehow.com/about_5608359_gel-electrophoresis_.html