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（三）胰島素和其他許多藥物，已經通過基因工程，在實驗室中製造。食品工業所需要多種的酵素，包括生產乾乳酪所用的動物胃中的凝乳酵素（rennet），已有基因工程生產的形式供應，應用廣泛。
（四）醫學研究者憑藉基因工程，摧毀攜帶病原的昆蟲的致病能力。他們目前經由基因工程製造人類皮膚（註9），並期待日後能製造完整的器官，以及人體其他的部位。
（五）基因篩檢已被應用於篩檢某些遺傳性的健康狀況，至於運用基因治療來矯正這些狀況的研究，目前仍在進行。尚有其他的研究，著重於直接在人類胚胎內進行基因改變的技術。最新近的研究也集中於基因工程和複製的結合，在所謂「成長系列療法（germline therapy）」中，基因的改變是永久的，將代代相傳。
（六）在採礦方面，目前正在研發經基因工程改造的微生物，將用來在礦脈中提取金、銅等礦物。日後更將有能在「甲烷氣」中存活的微生物，「甲烷氣」就是令礦工致命的「沼氣」。尚有其它經由基因工程改造的品種，已被應用於清除漏油、中和危險污染物以及吸收放射能。目前在發展階段中。經由基因工程改造的細菌，將可令廢物轉化成可作為燃料的乙醇。
名家之見
五十年代，媒體充斥著科學奇蹟將如何殺死全世界的害蟲、消滅昆蟲攜帶的疾病、餵飽全球饑餓人口的好消息，那就是DDT。到了九十年代，媒體滿載著有關基因工程未來美景的報導——處處可見基因工程將如何掃除饑饉，如何消滅疾病等等， 但問題在於代價。現陳述以下意見和引證，希望能幫助評估這個主要問題。
諸多傑出科學家已就基因工程的危險提出警告。諾貝爾獎得主、生物學家兼哈佛大學教授喬治•華德（George Wald）寫道：
脫氧核醣核酸（DNA）重組科技（基因工程）帶給社會的問題，無論在科學史上或對地球上的生命而言，都是史無前例的。重造生命的能力，乃是近三十億年來進化的結果，現在卻落到人類手裡。諸如此類的干預，絕不能與過去種種對生物天然秩序的干預，例如：人工繁殖動、植物，或以諸如愛科斯光等人工的方式，所引起的突變，混為一談。所有這些早期的程序，都在單一、或密切相關的品種內進行；而新科技的關鍵，在於將基因超越目前一切分隔生物彼此間的藩籬……而不僅在品種間前後轉移所得到的；實質上是形成新的生命，能自我繁衍，故能代代相傳，一經創造，就「放虎容易縛虎難」了……
在這之前，生物進化的過程非常緩慢，新生的種類有長足的時間適應環境……如今呢，整批蛋白質於旦夕之間調換成新的組合，而對於生物體本身，或是其鄰者所造成的影響，卻無人能預測。
由於基因工程太巨大、發生得太快了，所以這主要的問題幾乎仍未被思考過。在一切科學所必須面對的問題中，道德問題最為重大。到目前為止，我們的道德觀仍是：自然界中一切可學之物，人類都可以勇往直前、毫無限制地去學習；而重組大自然，並不包括在這份「交易」中……因為朝著這個方向前進，不但可能是不智的，更可能是危險的，尤其很可能從動植物培育出新疾病，新型癌症，和新傳染病。（註10）
卓越的基因學家、有時被譽為現代微生物學之父的艾文•沙格（Erwin Chargoff）評論道：
……最主要必須回答的問題是：我們是否有權力再將更沉重驚人的重擔，加在尚未出生的一代。我之所以用「更多」，乃有鑒於核子廢物問題至今尚未解決，已經夠恐怖的了。這個時代殃禍迭起，是因為我們需要請「阿斗」來扮行家定大略。還有什麼比創造生命型態的影響更長遠？ ……你可以停止分割原子，停止採訪月球，停止使用噴霧器；你甚至可以決定不使用幾顆炸彈來毀滅全人類，然而一旦造出一個新型態的生命，就如覆水難收。一旦你製造了一個可存活的大腸桿菌，它所攜帶的原形質的脫氧核醣核酸（DNA）是結合了單核或多核細胞核質的DNA時，它將會活得比你、你的兒女、你的後代還長久。對生物圈做出無可挽回的破壞。這在過去是前所未聞，也難以想像的一件事，但願我們這代人不曾造下這個罪業。[註11]
看來，在進行將一份動物的DNA併入微生物的原形質的重組實驗時，對其中的過程並不完全認知。在DNA鏈上，一個基因與其隔鄰的相關位置，是偶然的嗎？抑或它們彼此控制並互相調節？……大自然一直以來分隔開的東西，亦即是有核（eukaryotic）細胞的基因集（genomes）與無核（prokaryotic）細胞的基因集（genomes），我們卻準備將它們混合，這是明智之舉嗎？
最糟的是，我們永遠都不會知道這答案。一直以來，細菌和濾過性病原體一直在搞「地下黨」，它們對高等生物所發動的「游擊戰」，還並未被完全暸解。以無核生物來繁衍有核基因生命，是怪胎庫裡添怪胎，不啻為後代的生命蒙上模糊的面紗。人類智慧的進化已歷千萬年，難道僅為了滿足少數幾名科學家的野心與好奇，我們就有權來倒行逆施，走入不歸之路嗎？
這個世界只是暫借給我們用的——我們來了，又去了；不多時時間，我們又將大地、空氣、水留給後人。這一代人，或者上一代，以精密科學領軍，率先對大自然發動破壞性「殖民戰爭」——子孫們將為此詛咒我們。[註12]
附註：
9. 「聯邦食品藥物管理局批准（麻薩諸塞州坎滕市Canton, MA）『有機品創生（Organogenesis）公司』生產的 Apligraf® （移植用皮膚）上市。根據負責 Apligraf全球行銷的（紐澤西州東翰諾弗市E. Hanover, NJ）『諾瓦提斯製藥廠』（Norvatis Pharmaeuticals）所稱，此產品是唯一獲準在美國行銷的活的雙層皮膚組織。Apligraf近似人類的皮膚，有兩層主要的皮層，包括外在由活的角質細（Keratinocytes）組成的上皮層。Apligraf的真皮層含有活的人類纖維母細胞。該公司的發言人指出，用來生產Apligraf的人類角質細胞和纖維母細胞取自於捐者，是經過檢驗合格的，不攜帶傳染性病原體的。Apligraf是經由醫院門診部或傷科中心的醫師，應用在病人身上。」（一九九八年六月十五日版的〈基因工程新聞〉。）
10. 喬治•華德（George wald）所著「對基因工程的控訴」一文，收錄於強生與史蒂哲編輯的〈重組脫氧核醣核酸（DNA）的辯論〉第一二七與一二八頁。（翻印自一九七六年〈科學〉第九╱十月期。）
11. 艾文•沙格（Erwin Chargoff）著、紐約洛克斐勒大學出版社一九七八年出版的〈赫拉克賴脫之火：原始前生命素描圖（Sketches from a Life before Nature）〉第一八九頁。[註：紀元前五世紀的希臘哲學家赫拉克賴脫（Heraclitus）認為火是形成宇宙的主要的物質。]
12. 同上，第一九0頁。
待續
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3) Many pharmaceutical drugs, including insulin, are already genetically engineered in the laboratory Many enzymes used in the food industry, including rennet used in cheese production, are also available in genetically engineered form and are in widespread use.
4) Medical researchers are genetically engineering disease carrying insects so that their disease potency is destroyed. They are genetically engineering human skin9 and soon hope to do the same with entire organs and other body parts.
5) Genetic screening is already used to screen for some hereditary conditions. Research is ongoing in the use of gene therapy in the attempt to correct some of these conditions. Other research is focusing on techniques to make genetic changes directly in human embryos. Most recently research has also been focused on combining cloning with genetic engineering. In so-called germline therapy, the genetic changes are passed on from generation to generation and are permanent.
6) In mining, genetically engineered organisms are being developed to extract gold, copper, etc. from the substances in which they are embedded. Other organisms may someday live on the methane gas that is a lethal danger to miners. Still others have been genetically engineered to clean up oil spills, to neutralize dangerous pollutants, and to absorb radioactivity. Genetically engineered bacteria are being developed to transform waste products into ethanol for fuel.
SOME DISTINGUISHED SCIENTISTS' OPINIONS
In the 1950's, the media was full of information about the great new scientific miracle that was going to make it possible to kill all of the noxious insects in the world, to wipe out insect-born diseases and feed the world's starving masses. That was DDT. In the 1990's, the media is full of information about the coming wonders of genetic engineering. Everywhere are claims that genetic engineering will feed the starving, help eliminate disease, and so forth. The question is the price tag. The ideas and evidence presented below are intended to help evaluate that central question.
Many prominent scientists have warned against the dangers of genetic engineering. George Wald, Nobel Prize-winning biologist and Harvard professor, wrote:
Recombinant DNA technology [genetic engineering] faces our society with problems unprecedented not only in the history of science, but of life on the Earth. It places in human hands the capacity to redesign living organisms, the products of some three billion years of evolution. Such intervention must not be confused with previous intrusions upon the natural order of living organisms; animal and plant breeding, for example; or the artificial induction of mutations, as with X-rays. All such earlier procedures worked within single or closely related species. The nub of the new technology is to move genes back and forth, not only across species lines, but across any boundaries that now divide living organisms... The results will be essentially new organisms. Self-perpetuating and hence permanent. Once created, they cannot be recalled...
Up to now living organisms have evolved very slowly and new forms have had plenty of time to settle in.... Now whole proteins will be transposed overnight into wholly new associations, with consequences no one can foretell, either for the host organism or their neighbors.
It is all too big and is happening too fast. So this, the central problem, remains almost unconsidered. It presents probably the largest ethical problem that science has ever had to face. Our morality up to now has been to go ahead without restriction to learn all that we can about nature. Restructuring nature was not part of the bargain... For going ahead in this direction may be not only unwise but dangerous. Potentially, it could breed new animal and plant diseases, new sources of cancer, novel epidemics.10
Erwin Chargoff, an eminent geneticist who is sometimes called the father of modern microbiology, commented:
...The principle question to be answered is whether we have the right to put an additional fearful load on generations not yet born. I use the adjective 'additional' in view of the unresolved and equally fearful problem of the disposal of nuclear waste. Our time is cursed with the necessity for feeble men, masquerading as experts, to make enormously far-reaching decisions. Is there anything more far-reaching than the creation of forms of life?... You can stop splitting the atom; you can stop visiting the moon; you can stop using aerosols; you may even decide not to kill entire populations by the use of a few bombs. But you cannot recall a new form of life. Once you have constructed a viable E. coli cell carry a plasmid DNA into which a piece of eukaryotic DNA has been spliced, it will survive you and your children and your children's children. An irreversible attack on the biosphere is something so unheard-of, so unthinkable to previous generations, that I could only wish that mine had not been guilty of it.11
It appears that the recombination experiments in which a piece of animal DNA is incorporated into the DNA of a microbial plasmid are being performed without a full appreciation of what is going on. Is the position of one gene with respect to its neighbors on the DNA chain accidental or do they control and regulate each other? ... Are we wise in getting ready to mix up what nature has kept apart, namely the genomes of eukaryotic and prokaryotic cells.
The worst is that we shall never know. Bacteria and viruses have always formed a most effective biological underground. The guerrilla warfare through which they act on higher forms of life is only imperfectly understood. By adding to diis arsenal freakish forms of life-prokyarotes propagating eukaryotic genes—we shall be throwing a veil of uncertainties over the life of coming generations. Have we the right to counteract, irreversibly, the evolutionary wisdom of millions of years, in order to satisfy the ambition and curiosity of a few scientists? This world is given to us on loan. We come and we go; and after a time we leave earth and air and water to others who come after us. My generation, or perhaps the one preceding mine, has been the first to engage, under the leadership of the exact sciences, in a destructive colonial warfare against nature. The future will curse us for it.12
Notes:
9. "The FDA cleared Organogenesis' (Canton, MA) Apligraf® (graft-skin) for marketing. The product is the only living, bilayered skin construct approved for marketing in the US., according to Novartis Pharmaceuticals (E. Hanover, NJ), which will market Apligraf worldwide. Like human skin, Apligraf has two primary layers, including an outer epidermal layer made of living Keratinocytes. The dermal layer of Apligraf consists of living human fibroblasts. The human Keratinocytes and fibroblasts utilized to manufacture Apligraf are derived from donor tissue that is thoroughly screened for a wide range of infectious pathogens, notes a Novartis spokesperson. Apligraf is applied by a physician in a hospital outpatient facility or a wound care center." (Genetic Engineenng New, June 15, 1998.)
10. George Wald. "The Case Against Genetic Engineering."
The Recombinant DNA Debate. Jackson and Stich, eds. p. 127, 128. (Reprinted from
The Sciences, Sept./Oct. 1976 issue).
11. Erwin Chargoff, Heraclitean Fire : Sketches from a Life before Nature (New York: Rockefeller University Press, 1978), p. 189.
12. Ibid., p.190.
To be continued
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