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some questions related to plant DNA extraction

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some questions related to plant DNA extraction

Postby sara » Thu May 12, 2005 11:12 am

Hi,

There are some questions related to plant DNA extraction:

1. why the conc. of protein is differe from plant to plant? this is observe when i quantify the DNA by spectrophotometer.

2. why some plant contain polyssacaride and polyphenols than others.

3. when im doing the extraction to the same species ( one of them as replicate) , same procedure and at the same time i will find that the ratio, DNA conc., and purity are differrent although they are same . this is may be during the grinding that im grind one to fine powder which my DNA degraded by nucleases activity.

regards
sara
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Postby DevGrp » Thu May 12, 2005 3:17 pm

I think the problem is that there are some many different variables when it comes to extracting plant DNA: the state of the plants (age, development, degree of watering,) the parts of the plant, the amount of grinding, the timings, etc, etc etc all these lead to variability in DNA extraction. I must admit I've never had much faith in A260/280 ratios, they are very prone to mis-readings. We tend to run some sample on a gel against markers and do a functional assay (PCR /restriction digest). Fluorimetry (with Ethidium bromide / Hoescht ??? dye /Pico green) is another good way to quanitify DNA.

We're now trying out the Qiagen Biosprint15 DNA extraction machine, it seems to work well for our samples and is cheap to run, the only problem is the £9000 price tag to buy the thing in the first place!!

Good luck with your extractions


Ian
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Postby sara » Sat May 14, 2005 5:55 pm

hi,

thanks lan

im extract DNA from plant leave tissue, also i want to know why the conc. of protein and DNA are not unique in all plant although im using the same tissue (leave) and same weight (2g) in all plant.

some plant with polyphenols make difficult to load in wells so this will not give any band in DNA extraction gel.

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Postby muntedkowhai » Tue May 17, 2005 6:11 am

even though you're using the same plant and what not, the technique might be varialbe.(anywhere from extraction, resuspension etc)
how significantly diffferent are your concentrations?
largely?
or not so?
because it is hardly normal to have exact concentrations of dna extractions.
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