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DNA Testing Labs

Within the last decade, DNA (deoxyribonucleic acid) typing has provided scientists, police, investigators and attorneys with very valuable identification information. It has become the standard method for human identification. As research on the maps of chromosomes continues and new discoveries are made, the level of characterization of the human genome is reaching dramatic new levels. One of the most spectacular of the more recent scientific advancements has been the development of polymerase chain reaction (PCR) DNA typing.

PCR-based DNA typing is a very powerful technique for the analysis of biological evidence. PCR methods enable scientists to replicate a small amount of DNA obtained from minute stains millions of times. The amplified portion represents a particular variable region of the DNA, which may be analyzed by electrophoresis, a method used for separating molecules according their size and electrical charge.

PCR has many advantages over traditional methods, such as restriction fragment length polymorphism (RFLP) analysis, which include:

• The ability to analyze samples that are degraded by environmental factors such as heat, UV light, humidity and chemicals.
• The ability to analyze samples that have been exposed to microbial contamination.
• A short preparation and analysis time of only a few days (versus weeks for RFLP).
• The ability to analyze "difficult" samples such as cigarette butts, envelope flaps, semen, hair, and bone.
• Powerful discrimination potential.

PCR methods have been extensively validated by the scientific community and have a history of acceptance by courts throughout the country. Population studies have demonstrated that, in combination, these powerful tests can provide discrimination potentials in excess of 99.9%

Forensic Analytical provides high quality PCR-based DNA typing services and court qualified expert testimony to both the criminal and civil legal communities. Forensic Analytical's skilled experts are committed to accurate, reliable and timely results. Currently available PCR tests include the DQA1, Polymarker, and short tandem repeat (STR) loci.

Short Tandem Repeats (STRs) and Automated DNA Typing
Forensic Analytical has remained committed to being a technology leader and employing the most advanced techniques in DNA typing. Among the most recent advancements in the field of DNA typing is the ability to simultaneously analyze multiple genetic markers referred to as short tandem repeats (STRs). The analysis of multiple STR loci can increase discrimination potentials to values formerly achieved only by RFLP analysis. Analysis of STR loci is facilitated by the ability to label PCR products with fluorescent dyes which may be detected with capillary electrophoresis instruments such as the PE Applied Biosystems Prism 310 Genetic Analyzer. The sophisticated instrumentation and automation aids in the interpretation of analytical data and reduces the possibility of errors due to human handling. The AmpFl STR Profiler Plus kit utilized by Forensic Analytical affords the ability to simultaneously type nine STR loci and the sex marker, amelogenin. Specific markers include:

The technology used to detect and identify DNA in molds has become very accurate, reliable and cost effective. It has opened the possibility to speciate mold in indoor air quality applications in a manner that has never been accomplished before on a commercial level. To date, scientists have relied on years of training, experience and direct microscopic examination to arrive at the correct application of a name in the identifications of fungal molds. Since mycologists have identified over 100,000 different types of mold, traditional mycological techniques can be a daunting task. Additionally, traditional techniques require samples to be cultured in a suitable medium for 1 - 2 weeks (sometimes longer) for enumeration and identification. Traditional mycology can be a very labor-intensive task, even to the most experienced mycologists.

Molecular biology and research conducted at the USEPA's National Exposure Research Laboratory have changed this. Instead of samples being cultured for long periods of time (1 - 2 weeks), samples can be turned around on a very rapid turnaround (1 - 2 days). An instrument performs the identification and quantitation of mold. The end result is data that is derived faster and can be more accurate than conventional culture-based methods. In the instance of water intrusion molds, such as Stachybotrys, Penicillium and Aspergillus, accurate identification and measurement are crucial to an effective mold assessment. It offers flexibility of sampling, as media is not specific to the target mold. Additionally, loading of a sample is not as much of a concern as it is in optical microscopy.

Explanation of Deoxyribonucleic Acid DNA
Deoxyribonucleic Acid (DNA) is the genetic material found in all cellular organisms, including molds. This molecule encodes genetic information that is specific to the organism. DNA is comprised of base pairs of nucleotides arranged in a double helix, sometimes referred to as the building blocks of DNA. The four nucleotides in DNA contain the bases adenine (A), guanine (G), cytosine (C), and thymine (T). Base pairs form only between A and T and between G and C; thus the base sequence of each single strand can be deduced from that of its partner. Each DNA molecule is composed of two strands, which are complimentary to each other and form the double helix.

Explanation of Polymerase Chain Reaction (PCR)
Real-time polymerase chain reaction (PCR) based typing is the preferred technique for performing DNA typing of mold. Very little sample is required to perform the analysis, as the technique is extremely sensitive and precise. The method amplifies a mold's DNA base sequence into millions of copies using a heat-stable polymerase. By attaching a fluorescent probe to a unique region of a mold's DNA, one is able to qualitatively identify and quantitatively measure a species of mold from the sample.

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