Recently CNN.co.jp reported the following:
マンモス復活プロジェクトが始動、ゾウを遺伝子操作 １６億円の資金獲得
2021.09.14 Tue posted at 16:15 JST
（ＣＮＮ） 絶滅した生物の復活といえば、これまでＳＦの世界の出来事だった。映画「ジュラシック・パーク」の恐竜を復活させるという物語はその典型だった。
しかし遺伝学の進歩によって、失われた動物の復活は現実の出来事になりつつある。絶滅危惧種のクローン作製や、とうに絶滅した動物の骨や死骸から採取したＤＮＡの配列決定を成功させた研究もある。
マンモスを復活させれば、北極圏のツンドラ地帯の生態系を回復させ、気候危機とたたかい、マンモスに近い絶滅危惧種のアジアゾウを保護する助けになると関係者は期待する。ただしこの計画は倫理的問題もはらんでいる。
同プロジェクトを支援する生物科学・遺伝子会社コロッサルをチャーチ氏と共同で設立した起業家のベン・ラム氏は、「４～６年以内に最初の赤ちゃんを誕生させることを目指す」とした。
チャーチ氏は「２０２１年まで、これは一種の棚上げされたプロジェクトだった。だが今、それが実現可能になった」と指摘する。
チャーチ氏は最先端の遺伝学者で、人間への移植に適した臓器をもつブタ作製の実績などで知られる。
人間に臓器を移植できるブタを作製するためには４２の遺伝子改変を必要としたと同氏は説明。「ゾウの場合、目標は違っても改変の数はそれほど変わらない」と話す。
チャーチ氏によると、研究チームはこれまでに２３種のゾウと絶滅したマンモスの遺伝子を解析した。アジアゾウが北極圏で生存・繁殖できる特徴を獲得させるためには、アジアゾウの遺伝情報に「５０あまりの改変」を同時にプログラミングする必要があると推定している。
そうした特徴には、１０センチの断熱脂肪層、最大で長さが１メートルある５種類の体毛、寒さに耐えられる小さな耳などが含まれる。象牙目当ての密猟者に狙われないよう、牙が生えないようにする遺伝子操作も試みる。
そうした特徴を兼ね備えた細胞のプログラミングに成功すれば、人工子宮を使って胚（はい）から胎児へと成長させる計画。ゾウの場合、この過程には２２カ月を要する。ただ、この技術はまだ確立には程遠いとして、生きたゾウを代理母として使う可能性も排除していない。
マンモスの進化を専攻するストックホルム古遺伝学センターのロベ・ダレン教授は、この取り組みには科学的な価値があると考える。特に遺伝の病気があったり、近親交配で遺伝の多様性が失われている絶滅危惧種の保全に役立つという。
ただ、ここで生まれる動物はマンモスではなく、毛の長くて脂肪を蓄えたゾウだとも指摘。マンモスをマンモスたらしめる遺伝子の手がかりはほとんどないと語る。
一方、遺伝子操作した動物を誕生させる目的で、生きているゾウを代理母として使う点に倫理上問題があると指摘する声もある。ダレン氏は、マンモスとアジアゾウは人間とチンパンジーぐらい違うと語る。
また、ロンドン自然史博物館のマンモスの専門家トーリ・ヘリッジ氏は「マンモスを復活させて北極圏に住まわせ、北極圏を炭素の貯蔵庫としてより適した場所にするという考えには多くの問題がある」と指摘する。マンモスなどの草食動物が極北の地で草原を維持し、草を踏みつけ木を倒し、雪を圧縮することで永久凍土を保つという考えには、ダレン氏もヘリッジ氏も根拠がないと考える。ダレン氏は「マンモスをそこに置くことで気候変動に影響を与えられると示すものは何もない」と語る。
結局のところ、これまで述べられたような生態系の設計者としてのマンモス復活の目標は重要ではないかもしれない。多くの人々がマンモスに似た動物を近い距離で見てみたいと望む可能性がある。
ラム氏によると、このプロジェクトでは収益獲得へのプレッシャーはゼロだという。生命工学や医療の分野への応用がきくイノベーションにつながる可能性があり、ラム氏はプロジェクトをアポロ計画になぞらえる。同計画は宇宙探査について人々を心配させたが、結果的にＧＰＳなど多くのすばらしい技術につながったと同氏は語る。
Translation
(CNN) The resurrection of extinct creatures had been an event in the science fiction world. The story of reviving the dinosaurs in the movie "Jurassic Park" was a typical example.
But with advances in genetics, the resurrection of lost
animals was becoming a reality. Studies also succeeded in cloning endangered
species, and sequencing DNA from bones and carcasses of already extinct
animals.
A genetics research team led by Professor George Church of Harvard Medical School announced on the 13th that a project aimed at reviving a mammoth that was extinct 4000 years ago had secured an investment of 15 million dollars (about 1.65 billion yen). A future in which giant ice-age mammoths would be revived and inhabited in the natural environment was depicted.
Related people said the resurrection of the mammoth might help restore the Arctic Tundra ecosystem, fight the climate crisis, and protect the endangered Asian elephant that was closely related to the mammoth. However, this plan also had ethical issues.
"We aim to have our first baby within four to six years," said Ben Lam, an entrepreneur who together with Church, co-founded “Colossal”, a biological science and genetics company that supported the project.
Church said, "Until 2021, this was a kind of shelved project, but now it's feasible."
Mr. Church was a state-of-the-art geneticist and had been known for his track record of producing pigs with organs suitable for transplantation into humans.
He explained that he needed 42 genetic modifications to create a pig that could transplant organs into humans. "In the case of elephants, the number of modifications does not change much, even if the goals are different," he said.
According to Church so far, the research team had analyzed 23 genes of elephants and extinct mammoths. It was estimated that in order for Asian elephants to acquire the characteristics that allowed them to survive and reproduce in the Arctic Circle, it was necessary to simultaneously program "more than 50 modifications" in the genetic information of Asian elephants.
Such features would include a 10 cm insulating fat layer, 5 types of hair up to 1 meter in length, and small ears that could withstand the cold. They would also try genetic engineering to prevent tusks from growing so that they might not be targeted by poachers looking for ivory.
If they succeeded in programming cells that had these
characteristics, they planned to use an artificial womb to grow from an embryo to
a foetation. For elephants, this process took 22 months. However, this
technology was still far from being established, and they did not rule out the
possibility of using a living elephant as a surrogate mother.
Church said, "I think the editing will go well. We have a lot of experience in that. The production of artificial wombs is not guaranteed. This is not pure engineering, it has some scientific elements, so there is uncertainty. It will take longer to achieve."
Professor Love Dalén of the Stockholm Paleogenetic Center,
who majored in mammoth evolution, considered this effort to be of scientific
value. In particular, it was said to be useful for the conservation of
endangered species that had genetic diseases or had lost genetic diversity due
to inbreeding.
However, he also pointed out that the animals born here would not be mammoths, but long-haired, fat-storing elephants. He said he had few genetic clues on what made a mammoth a mammoth.
On the other hand, some had pointed out that there was an ethical problem in using a living elephant as a surrogate mother for the purpose of giving birth to a genetically engineered animal. Dalén said mammoths and Asian elephants were as different as humans and chimpanzees.
Mammoth expert Tori Herridge of the Natural History Museum
in London said, "There are many problems with the idea of reviving the
mammoths to live in the Arctic and making the Arctic a better place for carbon
storage.” Neither Dalén nor Herridge believed the idea that mammoths and other
herbivores could maintain grasslands in the far north, could trample grass,
knock down trees, and compress snow to preserve permafrost. Darren said, "There
is nothing to show that putting a mammoth there can affect climate change."
After all, the goal of a mammoth revival as an ecosystem designer as described above might not be important. Many people might want to see mammoth-like animals at close range.
According to Ben Lam, there was no pressure to make money on this project. Lam likened the project to the Apollo program, as it could lead to innovations that could be applied to biotechnology and medical fields. The Apollo plan had worried people regarding space exploration, but it resulted in many great technologies such as GPS, he said.
So, a
genetics research team led by Professor George Church of Harvard Medical School
has announced a project to create a mammoth like elephant. The research team's
goal is not to clone mammoths, but to manipulate genes to create hybrids of
elephants and mammoths that look like mammoths in appearance.
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