103 lines
5.3 KiB
Plaintext
103 lines
5.3 KiB
Plaintext
The following article is reproduced from the April 1984 issue of the MIT
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"Technology Review," page 85.
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Retrobreeding the Woolly Mammoth
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Last year in the Soviet Union, Dr. Sverbighooze Nikhiphorovitch
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Yasmilov, head of veterinary research at the University of Irkutsk,
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got hold of some cells - including some ova, or egg cells - from a
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young woolly mammoth found frozen in Siberia. Although the cytoplasm
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- the material forming the bulk of the cell - was unhealthy, Yasmilov
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was able to extract the nuclei. He implanted these into viable
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cytoplasm from elsewhere in the mammoth.
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Yasmilov continued his investigations by sending some cells to
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Dr. James Creak of MIT for testing. Creak heated the DNA from the
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mammoth ova until it dissolved into short lengths of code. After a
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number of false starts, he tried mixing it with a similarly prepared
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solution of the DNA of elephant sperm. The sections of elephant and
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mammoth code that matched "zipped themselves together," according to
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Creak, "as DNA is wont to do." This "paired DNA," representing the
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code common to elephants and woolly mammoths, was centrifuged off,
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leaving a residue of code that differed between the two species. The
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difference was less than 4.3%.
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This started Creak thinking. The elephant has 56 chromosomes,
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and the mammoth has 58. "Now look at the donkey and the horse," Creak
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explained. "The donkey has 62 chromosomes and the horse has 64, yet
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horses and donkeys can mate to produce mules and hinnies. So is it
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unreasonable to suggest an elephant-mammoth hybrid?"
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Creak communicated the good news at once to Yasmilov, who
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promptly set to work trying to fuse the nuclei from the mammoth ova,
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in their new cytoplasm, with sperm from an Asian elephant bull. As
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Creak points out, this delicate work requires highly skilled
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technicians. "In this profession," he observed, "people who can work
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with DNA and have it come out whole are traded like major-league
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baseball players, and they are even more valuable because the stakes
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are higher."
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Creak expressed concern about the state of experimental
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science in general. "Some scientists like to proceed in small,
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carefully thought-out steps. They are like accountants, and might as
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well be," he complained. "I see science as high adventure, with
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enormous risks. Of course, the rewards are commensurately high if the
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gamble comes off."
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Yasmilov attempted to artificially inseminate the mammoth ova
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with elephant sperm over 60 times before achieving fusion in eight
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samples. The resulting cell clusters were implanted in the wombs of
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Indian elephant cows. The timing of implantation is tricky, as the
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elephant cow must be in heat and proceed directly to the pregnant
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state after the embryo is implanted. Most of the elephant cows
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spontaneously miscarried, but two of the surrogate mothers carried to
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term, giving birth to the first known elephant-mammoth hybrids.
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Scientists have classified the calves as woolly mammoths
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according to two criteria. First, the yellow-brown hair that covered
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the newborn did not fall out after birth, as it does in "modern"
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elephants. Second, the calves' jaw structure closely resembles that
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of mammoths.
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Finding a scientific name for the young mammoth-elephant
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hybrid has been difficult. Professor Herman Hoffman of MIT's
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Linguistics Department suggests the word "mammontelephas" (it's
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singular), which he coined from the Russian "mammonth," or mammoth,
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and the Greek "elephas," or elephant. "It has - dare I say it? -
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almost a Byzantine ring," said Hoffman. Creak proposed the
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biological name "Elephas Pseudotherias," which would make the animals
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members of the Theria class of mammals. He added that the young
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mammontelephases belong to the order Proboscidea, having a long
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proboscis, or snout. It is not known whether the Russian scientists
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have classified the animals.
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Unfortunately for those who had hoped to breed the two
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mammals, both are male. They are probably sterile anyway, Creak
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points out. Mules are almost invariably sterile because they end up
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with an odd number of chromosomes - 31 (from the donkey parent) plus
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32 (from the horse parent), making a total of 63. The 63 chromosomes
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in the mule's body cells divide randomly into 31 or 32 in the gametes,
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or germ cells. When two mules mate, the pairs of germ cells are so
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unevenly matched that the chromosomes simply cannot pair up. In fact,
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the Roman expression for "once in a blue moon" was "cum mula peperit"
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- "when the mule foals."
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Although they will not reach adult size for another 25 years,
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the new mammoth calves have already exhibited extraordinary toughness
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by surviving the bitter cold of Irkutsk. They are being kept in an
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outdoor enclosure, and their reaction to the local weather conditions
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is being carefully monitored.
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Mindful of the elephants used by Hannibal and Alexander the
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Great in cold climes, Yasmilov plans to train the mammontelephases to
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earn their keep when they reach adulthood. They could help pull
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immobilized convoy trucks out of the snowdrifts on the Trans-Siberian
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highway. This is now a troublesome task, as the machinery employed to
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do the job may freeze in the bitter cold. The mammontelephases could
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also be used for logging, and there may even be a job on the
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Trans-Siberian pipeline.
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--- Diana ben-Aaron
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April 1, 1984
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