Analysis of Collected DNA
DNA identification of species can be a very useful tool in forensic entomology. Although it does not replace conventional identification of species through visual identification, it can be used to differentiate between two species of very similar or identical physical and behavioral characteristics. A thorough identification of the species through conventional methods is needed before an attempt at DNA analysis. This DNA can be obtained from practically any part of the insect, including the body, leg, setae, antennae, etc. There are about one million species described in the world and many more that have still not been identified. A project termed "the barcode of life" was launched by Dr. Paul D. N. Hebert, where he identified a gene that is used in cellular respiration by all species, but is different in every species. This difference in sequence can help entomologists easily identify two similar species.
DNA sequencing is basically done in three steps: polymerase chain reaction (PCR), followed by a sequencing reaction, then gel electrophoresis. PCR is a step that cleaves the long chain of chromosomes into much shorter and workable pieces. These pieces are used as patterns to create a set of fragments. These fragments are different in length from each other by one base which is helpful in identification. Those sets of fragments are then separated by gel electrophoresis. This process uses electricity to separate DNA fragments by size as they move through a gel matrix. With the presence of an electric current the negative DNA strand marches toward the positive pole of the current. The smaller DNA fragments move through the gel pores much more easily/faster than larger molecules. At the bottom of the gel the fragments go through a laser beam that emits a distinct color according to the base that passes through.
Read more about this topic: Use Of DNA In Forensic Entomology
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