Microarray technology..... definition,application,procedure,advantages

1. Microarray Technology

2. What Is A Microarray?
“A microarray is a tool for analyzing
gene expression that consists of a
small membrane or glass slide
containing samples of many genes
arranged in a regular pattern.”

3. Uses
• Analysis of gene expression
• SNP analysis
• MHC typing
• Identification of pathogens
• Identification of tumours

4. MICROARRAYS
• The underlying principle of microarray technology is the ability of
DNA to bind to itself and to RNA.
• Analyzing gene expression involves the detection of mRNA species
(transcriptome) present in a cell or tissue at a particular point in time.

5. Microarrays
RNA RNA
Cy3 labelled
cDNA
Cy5 labelled
cDNA
Hybridization

6. Evolution of Microarrays
• One gene / one experiment
– RT-PCR, northern blots, RNase assays
• Macroarrays
– Nylon membranes
– 32P labelled samples
• Microarrays
– Glass slides
– Fluorescent labelled samples
• Affymetrix

7. • There are 3 main types of microarrays
• Glass cDNA microarrays
• Glass oligonucleotide microarrays
• Affymetrix

8. Glass Microarrays
• cDNA arrays
– >1000 nucleotides in length
– cDNA libraries
• Oligonucleotide arrays
– 70-80 nucleotides in length
– Increased specificity

9. Affymetrix
• 25 nucleotides in length
• Mismatch pair
– Single mismatch at centre of probe
– Used to detect & eliminate false results
• 11 probe pairs per gene
• Photolithography

10. Bovine Microarrays
Microarray Format Source of Material
BOTL cDNA Bovine total leukocyte cDNA library & immune
gene amplicons
Pyxis CattleArray 7600 cDNA Bovine spleen & placental cDNA libraries
NBFGC cDNA MARC & BARC cDNA libraries
BMAM cDNA MARC & BARC cDNA libraries
Mammary gland specific
Endometrial/placental
microarray
cDNA Bovine placental & endometrial cDNA libraries
Bovine immune-endocrine
microarray
cDNA Bovine immune & endocrine gene amplicons
Bovine MHC class I
microarray
oligos BoLA DRB3 & DQA sequences
BoMP microarray
RIGUA
cDNA
Oligos
Bovine macrophage cDNA library
Bovine immune & inflammatory gene amplicons
Affymetrix oligos Various cDNA libraries
ARK-Genomics cDNA Various cDNA libraries

11. DNA MICROARRAYS CAN BE
USED TO DETECT DIFFERENCES
IN THE LEVELS GENE
EXPRESSION IN DIFFERENT
POPULATIONS OF CELLS ON A
GENOME-WIDE LEVEL.

12. GENE EXPRESSION = A GENE’S
ABILITY TO MAKE A GENE
PRODUCT.
MOST GENES CODE FOR
PROTEINS (PROTEIN ENCODING
GENES) THAT WHEN EXPRESSED,
PRODUCE A GENE-SPECIFIC
PROTEIN.

13. DNA MICROARRAYS
• A small 1 square centimeter chip that’s divided into thousands
of squares.
• Each square contains many copies of a single gene.
• Originally developed by Patrick Brown at the Stanford
University School of Medicine to determine which genes are
involved in yeast cell sporulation.

14. APPLICATIONS OF DNA
MICROARRAY ANALYSIS.
• Genes that are involved in the development of an organism.
• Genes that are activated as a family of genes (gene expression
profiling).
• Genes that are involved in human cancers.
• Earlier diagnosis of human cancers.

15. EXAMPLE OF A CANCER SUBTYPE
DETERMINED VIA DNA
MICROARRAY ANALYSIS.
• Two subtypes of diffuse large B cell lymphoma.
• One group of tumor cells expressed a large group of genes that
are involved in early B cell development.
• Another group of tumor cells expressed a large group of genes
that are involved in late B cell development.

16. Microarrays have many uses.
1. Major use is to investigate gene expression.
2. mRNA isolated from a cell gives a snap-shot of
the events occurring at that time.