Muhammad Tariq

Muhammad Tariq MMG07-27

DNA Microarray

DNA microarray 

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Is a multiplex technology used in molecular biology & in medicine. It consist of an arrayed series series of thousands of microscopic spots of DNA oligonuceotides, called features, each containing picomloles of a specific DNA sequence.

DNA Microarray 

In standard microarray, the probes are attached to a solid surface by a covalent bond to a chemical matrix(via epoxy-saline, lysine, polyacrylamide or others). The solid surface can be a glass or a silicon chip or colloquially affix chip when an affymetrix chip is used.

History  

Evolved from southern blotting. where fragment DNA is attached to a substrate & then probed with a known gene or fragment.

How microarray manufactured? 

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In different ways, depending on the number of probes under examination, costs, customization requirements, and the type of scientific question being asked. Preparation require cTags in printing buffer to a final conc. Of 25uM.

How microarray manufactured?  

If not used, store the cTags at -20c. Prepare the arrays by contact printing the cTag oligonucleotides onto code link activated slides using the prosy 5510Ainstrument with smp3 pins that deliver 1 nl of cTag solution to the slides as spots with diameters of 125150uM and a centre to center distance of , for example , 200uM.

How microarray manufactured? 

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To use the “array of arrays” format, print spots in a subarray pattern corresponding to the spacing of wells in a384- well micro titer plate. After arraying, mark the position of some of the subarrays on the backside of the slides using a diamond pin.

Uses 

Microarray is used in molecular biology and in medicine, in expression levels , SNP detection, in genotyping, forensic analysis, measuring predisposition to disease , identifying drug-candidates, evaluating germ line mutations in individuals or somatic mutations in cancers, assessing loss of heterozygosity, or genetic linkage analysis.

Uses( In yeast as a example)  

One common use in yeast. Which gene is activated or suppressed in aerobic & anaerobic conditions & which gene are expressed in both conditions out of 6000 genes.

Bioinformatics & microarray 

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Without computers and software microarray is nothing. As it is operated only with the help of computers & software. It is advance form of southern blotting, which takes a lot of time for results. Comparatively microarray give fast and 99.9% accurate results within few hours.

Bioinformatics & microarray 

Computer can interpret the results in the form of numerical manner, pi charts , histograms or in other graphical form according to our requirement.

Microarray databases        

Gene expression Omnibus-NCBI Stanford microarray database. Genevestigater database ArrayEpress at EBI UPenn RAD database MUSC database caArray at NCI UPSC- BASE