DNA+Microarray

__**DNA MICROARRAY**__


 * DNA microarray analysis was developed in the 1990s, has revolutionized the analysis of gene expression by monitoring the RNA product of many gene expression at once. One of the first descriptions of DNA microarray was in the literature by Augenlicht and his colleagues who spotted 400 complementary DNA or otherwise known as cDNA and used radioactive labeling to analyze gene expression. It is a systematic a way of looking at DNA and RNA by allowing it to examine so many gene at the same time, it allows for the study of gene expression patterns that underlie cell physiology. During microarray, we can see which genes expression are turned on or off as cells grows, divides and respond to hormones or toxins. The Microarray technology is a great benefit to help study the expression of all genes in a particular organism. DNA microarray are a little more than a glass microscope slides with a large amount of DNA fragments, the most dense array contains tens of thousands of fragment in a little area. Some microarray are prepared from long DNA fragment that has been generated while others are contain short oligonucleotides that are synthesized on the surface of glass wafer. Any nucleotide hybridizes to a probe on the array can be identified as the product of a specific gene just by the position of how the gene is bound. **

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 * The first step in performing an experiment using DNA microarray analysis is to collect samples that can be from, variety of organism (ex, cancerous human skin tissue and healthy human skin tissue). After collecting samples, mRNA would be extracted from both samples, using either a column or a solvent. The mRNA is then reversed transcribed in to cDNA and labeled with a florescent probe, either red (cyanine 5) or green (cyanine 3). The microarray is incubated with the cDNA sample and hybridization occurs. The array is then washed, so that the cDNA that is not tightly bound is removed. An automated scanner is used to identify the position in which the cDNA is bounded. **** If the gene expression levels increased the color is observed to be the same as labeled sample cDNA and if the expression levels decreased the color is the same as the reference cDNA. If there was no change in the expression levels relative the reference, the color is the mixing of two dyes utilized. Since microarray allow the simultaneous monitoring of large samples of genes, they can detect subtle changes in cells, changes that might not be manifested in its outward appearance or behavior.2 **


 * Influenza A is a virus that cause about 300,000-500,000 death per year across the globe and is still a threat to public health. To fight influenza viruses several approaches have been to taken such as efficient vaccine, drug development and so on. In this research paper, microarray analysis was used for the identification and sub typing of influenza viruses, influenza viruses are traditionally detected by using specific antibody based immunoassays.4 It is said that influenza viruses have multiple types and subtypes which shows high genetic variation and mutability. Microarray analysis was used to detect both influenza A and B viruses as well as various subtypes of influenza A viruses on the basis of three gene targets the HA, NA and M (Matrix) gene segments.4 Overall in all these experiments genes involved in immune response were found to be mainly affected by influenza virus infection. The genes specifically getting up-regulated in response to virus infection were interferon inducible genes, pro-inflammatory cytokines, and components. The use of microarray analysis has helped the researchers understand the virus of biology and interactions with its host. **


 * Another research experiment that used the technique of microarray analysis is to investigate the therapeutic mechanisms and drug development of Chinese medical herb. Chinese medical herb has been used for various treatments of diseases for centuries. Microarray provides a simple way to test the biomedical effects of herbs thereby gaining insights into their positive and negative side effects. Whole genome expression proﬁling can provide a basis for investigating the molecular mechanisms governing the therapeutic effects of Chinese herbal medicines and can be used to elucidate the biology of disease progression, identify potential therapeutic targets, and facilitate the development of traditional Chinese medicine-derived biopharmaceutical products.5 **


 * Lastly, here is another research experiment that used the technique of microarray technology for the detection and identification of Listeria monocytogenes in milk. L. monocytogenes can cause serious diseases such as meningitis, encephalitis, and sepsis insusceptible individuals, particularly infants, pregnant women, and the elderly and immunocompromised patients. Several techniques have been used to detect L. monocytogenes in milk such as culture-based and molecular methods, but it takes 7days to isolate L. monocytogenes from food. Since DNA microarray contains several thousands surface-immobilized DNA probe on a small glass slide, it can be as a faster way for microbial detection in one hybridization assay. A DNA microarray containing 60 random fragments of genomic DNA originating from L. monocytogenes strain ATCC 19111 was developed without sequence data.6 DNA microarray showed that 98-100% positive hybridization signals for L. monocytogenes. Overall the study showed that DNA microarray with random DNA fragment has a good potential for detecting and identifying L. monocytogenes. **


 * [2] Alberts, B., Johnson, A., Lewis, J., Raff, M., Roberts, K. & Walter, P. //Molecular Biology of the Cell: 5th Edition//. Garland Science, Taylor and Francis Group, LLC: New York. 2008 **


 * [3] Jizhong Zhou and Dorothea K. Thompson. //MICROARRAY TECHNOLOGY AND// **
 * //APPLICATIONS IN ENVIRONMENTAL MICROBIOLOGY //****. Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge,Tennessee 37831, USA. 2004 **


 *  [4] ** **Sanjay Mukherjee and Alok K. Chakrabarti//. Impact of Microarray Technology in Influenza Virus Research and Diagnostics. Microbial Containment Complex//. National Institute of Virology, Sus Road, Pashan, Pune -411021, India. 2012 **

= [5] [|Chia-Cheng Li], [|Hsin-Yi Lo] , [|Chien-Yun Hsiang] , [|Tin-Yun Ho]. // DNA microarray analysis as a tool to investigate the therapeutic mechanisms and drug development of Chinese medicinal herbs. // Graduate Institute of Chinese Medicine, China Medical University, Taichung, Taiwan. Department of Microbiology, China Medical University, Taichung, Taiwan. 2012 =


 * [6] Jihyun Bang, Larry R. Beuchat, Han Song, Man Bock Gu, Hyo-Ihl Chang, Heenam Stanley Kim, Jee-Hoon Ryu. //Development of a random genomic DNA microarray for the detection and identiﬁcation of Listeria monocytogenes in milk// **
 * Graduate School of Life Sciences and Biotechnology, Korea University, Anam-dong, Sungbuk-Ku, Seoul 136-701, Republic of Korea Center for Food Safety and Department of Food Science and Technology, University of Georgia, 1109 Experiment Street, Grifﬁn, Georgia 30223-1797, USA c Department of Medicine, College of Medicine, Korea University, Anam-Dong, Seongbuk-Gu, Seoul 136-705, Republic of Korea. 2013[[file:Doc2.docx]] **