DNA probes for human blood?

bhjelle at carina.unm.edu bhjelle at carina.unm.edu
Wed Nov 25 18:48:54 EST 1992


In article <1992Nov25.112402.1905 at gnv.ifas.ufl.edu> afc at gnv.ifas.ufl.edu writes:
>Hello all,
>
>We need to determine the source of the blood meal from field-collected
>mosquitoes.  Most people are using precipitin tests with polyclonal
>antibodies, but this is ridiculously expensive.  We are already using
>DNA probes to dot-blotted mosquito squashate to identify mosquito
>species, so now we would like to use the same technique for blood meal
>analysis.  The most important thing is whether the blood is human.  It
>would also be nice to know if it were bird, mammal, or reptile otherwise,
>but this is not critical.
>
>A Japanese group has just reported success with this using a chunk of
>a human globin gene with a Kpn repeat in it.
>
>Questions:
>
>Is Kpn the best repeat to use?  What about Alu?  We will be doing some
>work in South America, so crossreaction with other primates is a minor
>consideration.  Crossreaction with common mammals (cows, rodents, dogs,
>etc.) would be very bad.  Sensitivity might be a problem, since there
>won't be much DNA available, so we want a high copy repeat.

I don't know about the Kpn repeat, but if it is confined to the
globin cluster it may not have sufficient copy number to allow
sensitive detection of human DNA. Some primates (maybe all) have
their own version of Alu, but it would be hard to beat Alu
for sheer high copy number and specificity for primate DNA.

You can try human Cot 1 DNA as another alternative. Or you might
be able to use pure (sheared) human DNA probe, in the presence
of vast excess of cold insect DNA, if you do not want to prepare
Cot 1 DNA. You can check this out with reconstruction expts
in which you spike mosquito DNA with small amounts of human
DNA on a dotblot.

The nice thing about human Cot 1 DNA is that you can try competing
with cold DNA from likely primate contaminants and see if you
lose ability to detect human DNA. If not, you are in business.

>For detection of bird or reptile DNA, we can use a much lower copy number
>repeat since red blood cells are nucleated.  Any suggestions? 

Bird or reptile Cot 1 DNA comes to mind.

Have you considered PCR with species-specific oligonucleotide
probes? You can use rDNA sequences as a start.

Brian



More information about the Methods mailing list