Hair and DNA

[Revenged]

No idea... Do you know? Please share...

Yeah, i know

--> it's the non coding region of the DNA and they check for so called VNTR --> variable number of tandem repeats. These are repeats of a specific DNA-sequence that is repeated after each other

--> by taking 10 different VNTR you'll get a good identification method.

You can amplify the VNTR with PCR and than analyse on a gel, which yields to band pattern seen on television.

Yeah, you basically look for repeating sequences of DNA in the "junk DNA"... These regions of tandemly repeated sequences are called "satellite regions"... you also get smaller repeat regions called "minisatellite" and "microsatellites" regions...

[Revenged]

Can you please tell me if someone takes a lock of hair and it is over 5 years old and possibly does not have the follicles attached, is there anyway you can use this for DNA..I think I know the answer but replies would be good

Yes of course... Scientists have got DNA from bones from animals hundreds of thousand of years old...

You can use a technique called PCR which can replicate the quantity of DNA from a very very very very small source of DNA... You basically heat the DNA, add primer, cool to allow DNA polymerase to work on the strand... that doubles quantity of DNA... you repeat heating and cooling cycles until you have enough DNA for genetic analysis...

[Geordie Boy]

If there was no root present you could not PCR the DNA. I have heard that you can obtain mitochondrial DNA from a hair shaft, but i don't know the protocol.

There are other ways of analysing DNA for identification purposes other than tandem repeats although they are not as definitive..

For example, Restriction fragment length polymorphisms.
These are short pallandromic sequences dotted around the gene. Enzymes target these sequences and cut the DNA strand at these points. This leaves the DNA in fragments of various sizes depending on how many of these pallandromic sequences you have.

So when you PCR the gene, how far down the gel it goes will tell you the size of the frangments you have created.

[swati]

Can anyone recommend a reputable DNA company to do a paternity test?

[yongjj]

It can used for DNA testing as it contain mitochondrial DNA. Coincidently i've blogged bout hair DNA via http://dnamazing.com/hair-styles-and-dna-testing/

[mith]

how was it preserved?

[AngieJ2118]

OK guys...here you go:

Nuclear DNA can be extracted from hairs as long as they contain the root. The root is the portion of the hair that contains actual living cells which, in turn, contain nDNA.
There are many different extraction protocols to extract DNA, mainly proteinase K, NaOH, ethanol precipitaion, orgainc extraction, etc. Once the DNA is extracted, it is purified using a Microcon 100 concentrator or QIAGEN before it is amplified by PCR. After amplification, genetic analysis can be performed utilizing a number of commercial kits (ex. Identifiler, MiniFiler, etc) that detect alleles at specific markers (known as STRs) to obatin a genetic profile of the individual from which the hair was collected.

Alternatively, when a hair is naturally shed, it does not usually contain the hair root. It is just the shaft of the hair. This means that there are NO living cells present, thus, nuclear DNA CANNOT be extracted and analyzed. However, every cell contains mitochondira which provide energy. Mitochondrial cells contain their own type of DNA called mtDNA. Contrasting from nuclear DNA that is a double-helix, mtDNA is circular. It is very compact and has a coding region and a non-coding region.
Everything is performed the same for DNA extraction, purification, and PCR amplification, but analysis is completely different. Instead of mapping the alleles present at certain loci, the non-coding region of mtDNA contains two hypervariable regions (HV1 and HV2) that are prone to polymorphisms or variation. It is the sequencing of these two regions compared to what is termed as the revised Cambridge Reference Sequence that yeilds mtDNA analysis. mtDNA, however, CANNOT differentiate between two individuals like nuclear DNA can. mtDNA is passed down genetically through maternal lineage, so relatives who share a common female individual will have identical mtDNA. This presents a problem since male to male comparisons CANNOT be made through mtDNA analysis. For example, if you have a son and you want to test 2 individuals for paternity, mtDNA analysis will NOT help you in ANY way.
Also, mtDNA is far better preserved in cells than nuclear DNA so a lock of hair that is 5 years old should have no problem extracting mtDNA. In fact, there have been publications of extracting mtDNA from wholly mammoth hair!!

[canalon]

Just a quick reaction to this:

Mitochondrial cells contain their own type of DNA called mtDNA. Contrasting from nuclear DNA that is a double-helix, mtDNA is circular.

There is a big error here. genomic DNA and mtDNA both form a double helix: but gDNA is linear, while mtDNA is circular. And the DNA is chemically the same, the difference is the location in the cell.

[MrMistery]

And I don't like "mitochondrial cells"...