2. CONTENTS
Introduction
A brief history about DNA microarray
Three basic aspects of DNA microarray
-Coupling of oligonucleotides to a platform
- Preparing samples for detection and Hybridization
-Scanning and analysing the data
Applications
Limitations
Conclusion
References
3. INTRODUCTION
A DNA microarray (also commonly known as DNA chip or biochip).
DNA microarrays use gene sequencing and DNA transcription and
hybridization to analyze and identify thousands of genes simultaneously.
Scientists use DNA microarrays to measure the expression levels of large
numbers of genes simultaneously or to genotype multiple regions of a
genome.
DNA micro array is a set of oligonucleotide sequences representing
the entire set of genes of an organism, arranged in a grid pattern .
4. A BRIEF HISTORY ABOUT MICROARRAY TECHNOLOGY
(1991)
Patrick Brown(1992) David.R.Walt (1998)
5. Coupling of oligonucleotides to a platform(DNA microarray fabrication)
1) Inject printing fabrication
In this method high density DNA arrays to be made on glass substrate.
The diameter of the nozzles is in the micrometre scale.(1-100μm)
Accurate volume of solution at Pico litre ,spotted on to a microscopic
slide
Microarrayer Inkjet printhead
6. Development of a 3-Axes Robotic System for Making DNA Microarrays
Bhabha Atomic Research Centre
7. 2) Affymetrix gene chip technology
This method was first developed by Affymetrix Inc., company.
Here oligonucleotides are synthesized on a silicon chip using
photolithographic method.
Each features on a gene chip may be as small as 50 nm square.
Affymetrix uses several photo masks and lighting process to expose
reaction positions selectively on silicon plates, then attaching oligos on
to it.
11. Preparing samples for detection and hybridization
RNA is extracted from two different samples and converted in to cDNA ,
during which the cDNA is labelled with fluorescent compounds.
The two samples are then mixed together for comparison and hybridised
to the array.
12. Interpretation of microarray result
After hybridization is complete, each feature of a microarray grid is
scanned by a green laser and a red laser to detect the presence of both
control and test DNA hybridization .
A fluorescing DNA microarray showing the result of DNA hybridization
between the probe and target DNAs.
13. Applications of DNA microarray
Sequence analysis
Gene expression analysis: gene discovery
Identification of single nucleotide polymorphism
Whole genome association studies
14. Limitations of DNA microarray
The complexity of biological systems
The tissue sample
Microarray analysis will not detect certain chromosome rearrangements
We need to know in advance which genes we are looking for.
Non coding RNAs could not be analysed with this method
15.
16. REFERENCES
DNA microarray learning module,
Southwest centre for microsystem education,
New Mexico.
website: www.scme-nm.org
Roger Bumgarner, DNA microarray : Types, Application and their future,
current protocol molbio,2013 January, University of Washington.
http://www.ncbi.nlm.nih,gov/pmc/articles/PMC2659835
17. ACKNOWLEDGEMENT
I would like to thank my guide Dr. Amruthavalli for her
valuable guidance and also our course coordinator Dr.
N.S.Devaki for giving me this opportunity to present
my seminar.
Thank you all .