Jurassic Park - Crichton Michael - Страница 26
- Предыдущая
- 26/89
- Следующая
"As a matter of fact," Wu said, "there are two possible sources. Using the Loy antibody extraction technique, we can sometimes get DNA directly from dinosaur bones."
"What kind of a yield?" Grant asked.
"Well, most soluble protein is leached out during fossilization, but twenty percent of the proteins are still recoverable by grinding up the bones and using Loy's procedure. Dr. Loy himself has used it to obtain proteins from extinct Australian marsupials, as well as blood cells from ancient human remains. His technique is so refined it can work with a mere fifty nanograms of material. That's fifty-billionths of a gram."
"And you've adapted his technique here?" Grant asked.
"Only as a backup," Wu said. "As you can imagine, a twenty percent yield is insufficient for our work. We need the entire dinosaur DNA strand in order to clone. And we get it here." He held up one of the yellow stones. "From amber-the fossilized resin of prehistoric tree sap."
Grant looked at Ellie, then at Malcolm.
"That's really quite clever," Malcolm said, nodding.
"I still don't understand," Grant admitted.
"Tree sap," Wu explained, "often flows over insects and traps them. The insects are then perfectly preserved within the fossil. One finds all kinds of insects in amber-including biting insects that have sucked blood from larger animals."
"Sucked the blood," Grant repeated. His mouth fell open. "You mean sucked the blood of dinosaurs.
"Hopefully, yes."
"And then the insects are preserved in amber…" Grant shook his head. "I'll be damned-that just might work."
"I assure you, it does work," Wu said. He moved to one of the microscopes, where a technician positioned a piece of amber containing a fly under the microscope. On the video monitor, they watched as he inserted a long needle through the amber, into the thorax of the prehistoric fly.
"If this insect has any foreign blood cells, we may be able to extract them, and obtain paleo-DNA, the DNA of an extinct creature. We won't know for sure, of course, until we extract whatever is in there, replicate it, and test it. That is what we have been doing for five years now. It has been a long, slow process-but it has paid off.
"Actually, dinosaur DNA is somewhat easier to extract by this process than mammalian DNA. The reason is that mammalian red cells have no nuclei, and thus no DNA in their red cells. To clone a mammal, you must find a white cell, which is much rarer than red cells. But dinosaurs had nucleated red cells, as do modern birds. It is one of the many indications we have that dinosaurs aren't really reptiles at all. They are big leathery birds."
Tim saw that Dr. Grant still looked skeptical, and Dennis Nedry, the messy fat man, appeared completely uninterested, as if he knew it all already. Nedry kept looking impatiently toward the next room.
"I see Mr. Nedry has spotted the next phase of our work," Wu said. "How we identify the DNA we have extracted. For that, we use powerful computers."
They went through sliding doors into a chilled room. There was a loud humming sound. Two six-foot-tall round towers stood in the center of the room, and along the walls were rows of waist-high stainless-steel boxes. "This is our high-tech laundromat," Dr. Wu said. "The boxes along the walls are all Hamachi-Hood automated gene sequencers. They are being run, at very high speed, by the Cray XMP supercomputers, which are the towers in the center of the room. In essence, you are standing in the middle of an incredibly powerful genetics factory."
There were several monitors, all running so fast it was hard to see what they were showing. Wu pushed a button and slowed one image.
1 GCGTTGCTGG CGTTTTTCCA TAGGCTCCGC CCCCCTGACG AGCATCACAA AAATCGACGC
61 GGTGGCGAAA CCCGACAGGA CTATAAAGAT ACCAGGCGTT TCCCCCTGGA AGCTCCCTCG
121 TGTTCCGACC CTGCCGCTTA CCGGATACCT GTCCGCCTTT CTCCCTTCGG GAAGCCTGGC
181 TGCTCACGCT GTAGGTATCT CAGTTCGGTG TAGGTCGTTC GCTCCAAGCT GGGCTGTGTG
241 CCGTTCAGCC CGACCGCTGC GCCTTATCCG GTAACTATCG TCTTGAGTCC AACCCGGTAA
301 AGTAGGACAG GTGCCGGCAG CGCTCTGGGT CATTTTCGGC GAGAACCGCT TTCGCTGGAG
361 ATCGGCCTGT CGCTTGCGGT ATTCGGAATC TTGCACGCCC TCGCTCAAGC CTTCGTCACT
421 CCAAACGTTT CGGCGAGAAG CAGGCCATTA TCGCCGGCAT GGCGGCCGAC GCGCTGGGCT
481 GGCGTTCGCG ACGCGAGGCT GGATGGCCTT CCCCATTATG ATTCTTCTCG CTTCCGGCGG
541 CCCGCGTTGC AGGCCATGCT GTCCAGGCAG GTAGATGACG ACCATCAGGG ACAGCTTCAA
601 CGGCTCTTAC CAGCCTAACT TCGATCACTG GACCGCTGAT CGTCACGGCG ATTTATGCCG
661 CACATGGACG CGTTGCTGGC GTTTTTCCAT AGGCTCCGCC CCCCTGACGA GCATCACAAA
721 CAAGTCAGAG GTGGCGAAAC CCGACAGGAC TATAAAGATA CCAGGCGTTT CCCCCTGGAA
781 GCGCTCTCCT GTTCCGACCC TGCCGCTTAC CGGATACCTG TCCGCCTTTC TCCCTTCGGG
841 CTTTCTCAAT GCTCACGCTG TAGGTATCTC AGTTCGGTGT AGGTCGTTCG CTCCAAGCTG
901 ACGAACCCCC CGTTCAGCCC GACCGCTGCG CCTTATCCGG TAACTATCGT CTTGAGTCCA
961 ACACGACTTA ACGGGTTGGC ATGGATTGTA GGCGCCGCCC TATACCTTGT CTGCCTCCCC
1021 GCGGTGCATG GAGCCGGGCC ACCTCGACCT GAATGGAAGC CGGCGGCACC TCGCTAACGG
1081 CCAAGAATTG GAGCCAATCA ATTCTTGCGG AGAACTGTGA ATGCGCAAAC CAACCCTTGG
1141 CCATCGCGTC CGCCATCTCC AGCAGCCGCA CGCGGCGCAT CTCGGGCAGC GTTGGGTCCT
1201 GCGCATGATC GTGCT… CCTGTCGTTG AGGACCCGGC TAGGCTGGCG GGGTTGCCTT
1281 AGAATGAATC ACCGATACGC GAGCGAACGT GAAGCGACTG CTGCTGCAAA ACGTCTGCGA
1341 AACATGAATG GTCTTCGGTT TCCGTGTTTC GTAAAGTCTG GAAACGCGGA AGTCAGCGCC
"Here you see the actual structure of a small fragment of dinosaur DNA," Wu said. "Notice the sequence is made up of four basic compounds-adenine, thymine, guanine, and cytosine. This amount of DNA probably contains instructions to make a single protein-say, a hormone or an enzyme. The full DNA molecule contains three billion of these bases. If we looked at a screen like this once a second, for eight hours a day, it'd still take more than two years to look at the entire DNA strand. It's that big."
He pointed to the image. "This is a typical example, because you see the DNA has an error, down here in line 1201. Much of the DNA we extract is fragmented or incomplete. So the first thing we have to do is repair it-or rather, the computer has to. It'll cut the DNA, using what are called restriction enzymes. The computer will select a variety of enzymes that might do the job."
1 GCGTTGCTGGCGTTTTTCCATAGGGTCCGCCCCCCTGACGAGCATCACAAAAATCGACGC
61 GGTGGCGAAACCCGACAGGACTFITAAAGATACCAGGCGTTTCCCCCTGGAAGCTCCCTCG
NspO4
121 TGTTCCGACCCTGCCGCTTACCGGATACCTGTCCGCCTTTCTCCCTTCGGGAAGCGTGGC
181 TGCTCACGCTGTAGGTATCTCAGTTCGGTGTAGGTCGTTCGCTCCASGCTGGGCTGTGTG
BrontIV
241 CCGTTCAGCCCGACCGCTGCGCCTTATCCGGTAACTATCGTCTTGAGTCCAACCCGGTAA
301 AGTAGGACAGGTGCCGGCAGCGCTCTGGGTCATTTTCGGCGAGGACCGCTTTCGCTGGAG
434 DnxTl AoliBn
361 ATCGGCCTGTCGCTTGCGGTATTCGCAATCTTGCACGCCCTCGCTCAAGCCTTCGTCACT
421 CCAAACGTTTCGGCGAGAAGCAGGCCATAATCGCCGGCATGGCGGCCGACGCGCTGGGCT
481 GGCGTTCGCGACGCGAGGCTGGATGGCCTTCCCCATTATGATTCTTCTCGCTTCCGGCGG
541 CCCGCGTTGCAGGCCATGCTGTCCAGGCAGGTAGATGACGHCCATCAGGGACAGCTTCAA
601 CGGCTCTTACCAGCCTAACTTCGATCACTGGACCGCTGATCGTCACGGCGATTTATGCCG
Nsp04
661 CACATGGACCCGTTGCTGGCGTTTTTCCATAGGCTCCGCCCCCCTGACGAGCATCACAAA
721 CAAGTCAGAGGTGGCGAAACCCOACAGOACTATAAAGATACCAOOCOTTTCCCCCTGGAA
924 Caoll I DinoLdn
781 GCGCTCTCCTOTTCCOACCCTOCCOCTTACCOGATACCTOTCCOCCTTTCTCCCTTCGGG
841 CTTTCTCAATOCTCACOCTGTABGTATCTCAGTTCGGTOTAGGTCGTTCOCTCCAAOCTO
901 ACGAACCCCCCOTTCAGCCCGACCGCTGCGCCTTATCCGGTAACTATCGTCTTGAOTCCA
961 ACACOACTTAACCOOTTOOCATGGATTGTAGGCGCCGCCCTATACCTTGTCTOCCTCCCC
1021 GCGGTGCATGOAOCCOGOCCACCTCGACCTGAATOGAAGCCGOCGOCACCTCOCTAACOG
1081 CCAAGAATTGGAGCCAATCAATTCTTGCGGAGAACTGTGAATGCGCAAACCAACCCTTGG
1141 CCATCGCGTCCGCCATCTCCAGCAGCCGCACGCGGCGCATCTCGGGCAGCGTTGGGTCCT
1416 DnxTI
SSpd4
1201 GCGCATGATCGTGCT:+=:CCTGTCGTTGAGGACCCGGCTAGGCTGGCGGGGTTGCCTTACT
1281 ATGAATCACCGATACGCGAGCGAACGTGAAGCGACTGCTGCTGCAAAACGTCTGCGACCT
"Here is the same section of DNA, with the points of the restriction enzymes located. As you can see in line 1201, two enzymes will cut on either side of the damaged point. Ordinarily we let the computers decide which to use. But we also need to know what base pairs we should insert to repair the injury. For that, we have to align various cut fragments, like so."
[picture]
"Now we are finding a fragment of DNA that overlaps the injury area, and will tell us what is missing. And you can see we can find it, and go ahead and make the repair. The dark bars you see arc restriction fragments-small sections of dinosaur DNA, broken by enzymes and then analyzed. The computer is now recombining them, by searching for overlapping sections of code. It's a little bit like putting a puzzle together. The computer can do it very rapidly."
1 GCGTTGCTGGCGTTTTTCCATAGGCTCCGCCCCCCTGACGAGCATCACAAAAATCGACGC
61 GGTGGCGAAACCCGACAGGACTATAAAGATACCAGGCGTTTCCCCCTGGAAGCTCCCTCG
121 TGTTCCGACCCTGCCGCTTACCGGATACCTGTCCGCCTTTCTCCCTTCGGGAAGCCTGGC
181 TGCTCACGCTGTAGGTATCTCAGTTCGGTGTAGGTCGTTCGCTCCAAGCTGGGCTGTGTG
241 CCGTTCAGCCCGACCGCTGCGCCTTATCCGGTAACTATCGTCTTGAGTCCAACCCGGTAA
301 AGTAGGACAGGTGCCGGCAGCGCTCTGGGTCATTTTCGGCGAGAACCGCTTTCGCTGGAG
361 ATCGGCCTGTCGCTTGCGGTATTCGGAATCTTGCACGCCCTCGCTCAAGCCTTCGTCACT
421 CCAAACGTTTCGGCGAGAAGCAGGCCATTATCGCCGGCATGGCGGCCGACGCGCTGGGCT
481 GGCGTTCGCGACGCGAGGCTGGATGGCCTTCCCCATTATGATTCTTCTCGCTTCCGGCGG
541 CCCGCGTTGCAGGCCATGCTGTCCAGGCAGGTAGATGACGACCATCAGGGACAGCTTCAA
601 CGGCTCTTACCAGCCTAACTTCGATCACTGGACCGCTGATCGTCACGGCGATTTATGCCG
661 CACATGGACGCGTTGCTGGCGTTTTTCCATAGGCTCCGCCCCCCTGACGAGCATCACAAA
721 CAAGTCAGAGGTGGCGAAACCCGACAGGACTATAAAGATA CCAGGCGTTTCCCCCTGGAA
781 GCGCTCTCCTGTTCCGACCCTGCCGCTTACCGGATACCTGTCCGCCTTTCTCCCTTCGGG
841 CTTTCTCAATGCTCACGCTGTAGGTATCTC AGTTCGGTGTAGGTCGTTCGCTCCAAGCTG
901 ACGAACCCCCCGTTCAGCCCGACCGCTGCGCCTTATCCGGTAACTATCGTCTTGAGTCCA
961 ACACGACTTAACGGGTTGGCATGGATTGTAGGCGCCGCCCTATACCTTGTCTGCCTCCCC
1021 GCGGTGCATGGAGCCGGGCCACCTCGACCTGAATGGAAGCCGGCGGCACCTCGCTAACGG
1081 CCAAGAATTGGAGCCAATCAATTCTTGCGGAGAACTGTGAATGCGCAAACCAACCCTTGG
1141 CCATCGCGTCCGCCATCTCCAGCAGCCGCACGCGGCGCATCTCGGGCAGCGTTGGGTCCT
1201 GCGCATGATCGTGCTAGCCTGTCGTTGAGGACCCGGCTAGGCTGGCGGGGTTGCCTT
1281 AGAATGAATCACCGATACGCGAGCGAACGTGAAGCGACTG CTGCTGCAAAACGTCTGCGA
1341 AACATGAATGGTCTTCGGTTTCCGTGTTTC GTAAAGTCTGGAAACGCGGAAGTCAGCGCC
"And here is the revised DNA strand, repaired by the computer. The operation you've witnessed would have taken months in a conventional lab, but we can do it in seconds."
- Предыдущая
- 26/89
- Следующая
