jyamato@cory.Berkeley.EDU (YAMATO JON AYAO) (08/01/88)
In article <2887@calmasd.GE.COM> jnp@calmasd.GE.COM (John Pantone) writes: >I'm sure I read recently (within the last year or so) about just such >an effort being done in Siberia - except that instead of trying to >actually clone the mammoth, they took DNA and did a recombinant number >on elephant DNA - to "clone a hybrid" to coin (clone?) a phrase :-) >Anyone else hear/read about this - what was the result? >John M. Pantone @ GE/Calma R&D, 9805 Scranton Rd., San Diego, CA 92121 >...{ucbvax|decvax}!sdcsvax!calmasd!jnp jnp@calmasd.GE.COM GEnie: J.PANTONE I don't know about this one, but two gene sequences were isolated from the hide of a preserved museum quagga (a recently extinct zebra-like animal) by similar techniques. However, with maybe 500,000 genes in a higher organism (plus all the non-DNA information in the cell) this is a long way from being able to reconsititute the quagga... The new Polymerase Chain Reaction DNA-amplification method is supposed to be powerful enough to produce useful quantities of DNA from a single hair, so this kind of trick may become more common in the future. The limiting problem, I think, is fragmentation of the DNA--if your sample does not contain at least one intact copy of the desired gene you're out of luck. Also, PCR requires that you know what you're looking for. Mary Kuhner
lampman@heurikon.UUCP (Ray Lampman) (08/01/88)
In article <4786@pasteur.Berkeley.EDU> jyamato@cory.Berkeley.EDU.UUCP (YAMATO JON AYAO) writes: >The limiting problem, I think, is fragmentation of the DNA--if your sample >does not contain at least one intact copy of the desired gene you're >out of luck. > > Mary Kuhner Fragmemtation is not a problem if multiple copies of the damaged DNA are available. Just collect numerous samples and average out the damage. -- I am seriously considering a career on | Ray Lampman (608) 276-3431 the beach. I'll need a microwave modem, | Madison Wisconsin USA Earth solar power supply, and a little shade. | {husc6,rutgers}!uwvax!heurikon!lampman
boyle@jif.berkeley.edu (joseph boyle) (08/02/88)
In article <4786@pasteur.Berkeley.EDU> jyamato@cory.Berkeley.EDU.UUCP (YAMATO JON AYAO) writes: >I don't know about this one, but two gene sequences were isolated from >the hide of a preserved museum quagga (a recently extinct zebra-like >animal) by similar techniques. However, with maybe 500,000 genes in >a higher organism (plus all the non-DNA information in the cell) this >is a long way from being able to reconsititute the quagga... >The new Polymerase Chain Reaction DNA-amplification method is supposed >to be powerful enough to produce useful quantities of DNA from a single >hair, so this kind of trick may become more common in the future. The >limiting problem, I think, is fragmentation of the DNA--if your sample >does not contain at least one intact copy of the desired gene you're >out of luck. Also, PCR requires that you know what you're looking >for. Mary Kuhner PCR uses primers specific to the sequence you want to amplify so the sequence can be distinguished from background noise. It should be as possible to take a single unknown piece of DNA and amplify it, if it is the only original DNA sequence in the reaction cell. So the DNA fragments from the quagga or mammoth or whatever could be diluted and split up so that each sample was only likely to contain one fragment, then amplified separately. Having the fragments is one thing, but putting them together is another. Overlap would give some clues, although maybe not enough. If not, could intact DNA from a similar existing species be used as a (partial) template?
jyamato@cory.Berkeley.EDU (YAMATO JON AYAO) (08/04/88)
In article <252@heurikon.UUCP> lampman@heurikon.UUCP (Ray Lampman) writes: >In article <4786@pasteur.Berkeley.EDU> jyamato@cory.Berkeley.EDU.UUCP (YAMATO JON AYAO) writes: >>The limiting problem, I think, is fragmentation of the DNA--if your sample >>does not contain at least one intact copy of the desired gene you're >>out of luck. >> >> Mary Kuhner > >Fragmemtation is not a problem if multiple copies of the damaged DNA are >available. Just collect numerous samples and average out the damage. >-- >I am seriously considering a career on | Ray Lampman (608) 276-3431 >the beach. I'll need a microwave modem, | Madison Wisconsin USA Earth My understanding of the PCR technique is that, since it depends on chain synthesis starting from primers at both ends of a defined piece of DNA, it will fail if the ends aren't connected to each other. I could be wrong. At the American Society of Naturalists meeting I saw a nice presentation on the use of PCR to sequence *outward* from two defined primers (by circularizing the DNA!), a trick several people had told me was impossible. Mary Kuhner
bob@etive.ed.ac.uk (Bob Gray) (08/04/88)
In article <12860@agate.BERKELEY.EDU> boyle@jif.UUCP (joseph boyle) writes: >...... So the DNA >fragments from the quagga or mammoth or whatever could be diluted and >split up so that each sample was only likely to contain one fragment, >then amplified separately. Be careful and use properly treated water to do the dilutions with, a recent report in "Nature" suggests you could end up with a whole mammoth if you dilute the solution enough. :-> Bob.