按键盘上方向键 ← 或 → 可快速上下翻页，按键盘上的 Enter 键可回到本书目录页，按键盘上方向键 ↑ 可回到本页顶部！
————未阅读完？加入书签已便下次继续阅读！
They paused before windows and peered into a darkened room that looked like a small version of Mission Control。 There was a vertical glass see…through map of the park； and facing it a bank of glowing puter consoles… Some of the screens displayed data； but most of them showed video images from around the park。 There were just two people inside； standing and talking。
〃The man on the left is our chief engineer； John Arnold〃…Regis pointed to a thin man in a button…down short…sleeve shirt and tie； smoking a cigarette…〃and next to him； our park warden； Mr。 Robert Muldoon； the famous white bunter from Nairobi。〃 Muldoon was a burly man in khaki； sunglasses dangling from his shirt pockct。 He glanced out at the group； gave a brief nod； and turned back to the puter screens。 〃I'm sure you want to see this room；〃 Ed Regis said； 〃but first； let's see how we obtain dinosaur DNA。〃
The sign on the door said EXTRACTIONS and； like all the doors in the laboratory building； it opened with a security card。 Ed Regis slipped the card in the slot； the light blinked； and the door opened。
Inside； Tim saw a small room bathed in green light。 Four technicians in lab coats were peering into double…barreled stereo microscopes； or looking at images on high resolution video screens。 The room was filled with yellow stones。 The stones were in glass shelves； in cardboard boxes； in large pull…out trays。 Each stone was tagged and numbered in black ink。
Regis introduced Henry Wu； a slender man in his thirties。 〃Dr。 Wu is our chief geneticist。 I'll let him explain what we do here。〃
Henry Wu smiled。 〃At least I'll try；〃 he said。 〃Genetics is a bit plicated。 But you're probably wondering where our dinosaur DNA es from。〃
〃It crossed my mind；〃 Grant said。
〃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 pletely 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 puters。〃
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 superputers； 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 pounds…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 inplete。 So the first thing we have to do is repair it…or rather； the puter has to。 It'll cut the DNA； using what are called restriction enzymes。 The puter will select a variety of enzymes that might do the job。〃
1 GCGTTGCTGGCGTTTTTCCATAGGGTCCGCCCCCCTGACGAGCATCACAAAAATCGACGC
61 GGTGGCGAAACCCGACAGGACTFITAAAGATACCAGGCGTTTCCCCCTGGAAGCTCCCTCG
NspO4
121 TGTTCCGACCCTGCCGCTTACCGGATACCTGTCCGCCTTTCTCCCTTCGGGAAGCGTGGC
181 TGCTCACGCTGTAGGTATCTCAGTTCGG