Information about microarray history, principle, DNA microarray and types, working and equipment's and uses.

1. MICROARRAY
R. PERUMAL
2016603110
M. Sc., FLORICULTURE & LANDSCAPING

2. WHAT IS ARRAY???
 An array is an orderly arrangement of samples
where matching of known and unknown DNA
samples is done based on base pairing rules.
 An array experiment makes use of common assay
systems such as microplates or standard blotting
membranes.

3. HISTORICAL BACKGROUND
 Microarray technology evolved from
Southern blotting
 The concept of DNA microarrays began in
the mid 1980s.
 Mark Schena was proclaimed as the
“Father of Microarray Technology”
Mark Schena

4. MICROARRAY
 Microarrays are sets of miniaturized chemical
reaction areas that may be used to test DNA
fragments, antibodies, or proteins
 Each reaction area or spot is having immobilised
target which is hybridised with complimentary probe
present in the testing sample

5. PRINCIPLE
 The core principle behind microarrays is hybridization
between two DNA strands.
 Fluorescent labeled target sequences that bind to a
probe sequence generate a signal that depends on the
strength of the hybridization determined by the number
of paired bases.

6. “Microarray” has become a general term, there are many
types now
 DNA microarrays
 Protein microarrays
 Transfection microarrays
 Antibody microarray
 Tissue microarray
 Chemical compound microarray

7. DNA MICROARRAY
 A DNA microarray is a collection of microscopic DNA spots on solid
surface. Each spot contains pico moles of a specific DNA sequence,
known as probes or reporters
 Used for detection of polymorphisms and mutations in genomic DNA
 Commonly known as DNA chip, DNA arrays or biochips
 Bio chip is a small rectangular solid surface that is made of glass or
silicone

8. TYPES OF DNA MICROARRAY
i. Glass cDNA microarrays which involves the micro spotting of pre-
fabricated cDNA fragments on a glass slide.
ii. High-density oligonucleotide microarrays often referred to as a
"chip" which involves in situ oligonucleotide synthesis.

9. STEPS
I. Collect Samples
II. Isolate mRNA
III. Create Labelled DNA
IV. Hybridization
V. Microarray Scanner
VI. Analyze Data

10. EQUIPMENT'S

11. HYBRIDIZATION
Hybridization for 16-20 hrs at 45-60⁰ C

13. IMAGE ACQUISITION
 Unbound material is washed away
and the sample hybridized to each
element is visualized by
fluorescence detection.
 Fluorescence emission from the
microarray is converted into a
digital output for each dye, and is
stored as separate image files.

14. DNA MICROARRAY SCANNER
Fluorescent intensity is measured

15. THE COLOURS OF A MICROARRAY
 GREEN represents Control DNA, where either DNA or cDNA
derived from normal tissue is hybridized to the target DNA.
 RED represents Sample DNA, where either DNA or cDNA is
derived from diseased tissue hybridized to the target DNA.
 YELLOW represents a combination of Control and Sample
DNA, where both hybridized equally to the target DNA.
 BLACK represents areas where neither the Control nor
Sample DNA hybridized to the target DNA.

18. APPLICATIONS OF MICROARRAY TECHNOLOGY

19. CONCLUSION
Microarrays measure the concentration of mRNA
Several assumptions are made in the progress of analysis
Biological
Numerical
Experimental conditions are important!
Different distances matrics combined with different clustering
algorithms can leed to completely different results

20. THANK YOU