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DNA chip
"DNA chip" is a technology to read the performance of DNA easily by complementary of DNA.
You can check on mRNA working in the cell in reality.
So far it takes great deal of time to look over the to what extent of DNA.
However, you can know whole genome information by the technology on the a slide or a silicon substrate.
There are two DNA chip methods now.
"Gene Chip" by Affymetrix company in America
"cDNA microarray" by Stanford University
We show the method, "cDNA microarry", here.
The method needs two preparation.
Preparation of the silicon substance
First, you prepare the silicon substance.
You put cDNA onto the board.
"cDNA" is the , they are complementarity DNA, can connect with mRNA.
cDNA is made from mRNA by the reverse transcriptase.
It is important for the method to connect with particular mRNA.
(Recently, it is liked the oligonucleotide made by the art of man rather than putting cDNA. We can create it for the purpoce freely, so we get more details data.)
Prepared cDNA are put onto the board, but we must do the number of gene times, in other words, tens of thousands cDNA are done.
It is impossible with human's hands.
Then, the machine, "Spotter" is used.
Spotter sticks cDNA to the tip of its pin and sticks it on the board by pressing.
There are some technology to stick for example inkjet methods, spraying as a inkjet printer, bubble jet methods, heating the pin to make bubbles and spraying by the pressure of bubbles. It is researched by some people.
Preparation of the cell
Second, you prepare the cell.
You find the cell you want to check on, it is said "sample specimen".
Besides, you find another healthy cell, it is said "control specimen".
Each cells make each mRNA, so we can know the performances of the gene by comparing the performances of mRNA.
If sample specimen makes two mRNA and control specimen makes only one mRNA, sample specimen is active in the gene.
Of course, you can use a cell and compare it with another data.
mRNA are took out from these cells and put different colors on each mRNA.
In generally, fluorescent dyes is used.
Cy5, red dye is used to sample specimen and Cy3, green dye is used to control specimen here.
Hybridization
It is finished both of preparation, let's react mRNA with the board.
The complement makes mRNA connect with cDNA.
You know the places and the kinds of cDNA, so all you have to do is read the connected amount.
You read the amount by skaning the fluorescent dyes.
The color will appear strongly, if a lot of mRNA connect.
If red is strong, sample specimen is active, and if green is strong, control specimen is active, and if yellow, mixed, is strong, both of them are active there.
We find the unhealthy gene by comparing them.
(Fluorescent dye is used in this example, but there is a method by checking on the conductivity by connecting with the non-conductive materials. It is researched for low costs and quickly checking now.)
Thus, we could know the performances of genes.
It may be more familiar the DNA tests with developing the technology.
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