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Where oa. mee From by Nissa Genetic Engineering Where To From Here? by Nissa At this point in history, with the advances being made in technology and the sciences, there’s always room for more reportage on genetic engineering. This is an update in our series on this topic. Almost all human cells contain 46 chromosomes, which contain our DNA. There are approximately six billion nucleotides (or bases) in the human genome and about 100,000 genes in homo sapiens, each one accounting for about 1,000 pairs of these bases. More than 95% of the genetic message, therefore, appears to be redundant - it doesn’t appear to contribute to the genes that code our life-giving proteins. More advanced technology must be invented to read the full sequence and build maps of the human genome. In 1988 one re- searcher can decode between 50,000 and 100,000 bases per year. A complete sequence would need nearly 1,500 full time researchers working for a year. One problem is handling larger pieces of DNA. Genetic engineers have used bacteria and viruses to ‘amplify’ smaller sections of DNA, but this only extends to DNA fragments of up to 40,000 bases. Cloning or duplication of those pieces has improved, but to give a complete picture of the genome would require roughly 1.5 million laboratory clones. : ™ Dr. Maynard Olsen of Washington University, St, Louis, has TWO G E nN ETI c co D ES reported a technique for constructing artificial yeast chromosomes that carry 30,000 to 40,000 bases of inserted DNA. If these artificial chromosomes can be improved tenfold, the number of clones needed Scientists at the U.S. Massachusetts Institute of Technology have for a complete library would drop to a manageable size. made a breakthrough in understanding how cells carry out their work At this point in history, with the advances being made in technology and the sciences, there’s always room for more reportage on genetic engineering. This is an update in our series on this topic. Almost all human cells contain 46 chromosomes, which contain our DNA. There are approximately six billion nucleotides (or bases) in the human genome and about 100,000 genes in homo sapiens, each one accounting for about 1,000 pairs of these bases. More than 95% of the genetic message, therefore, appears to be redundant - it doesn’t appear to contribute to the genes that code our life-giving proteins. More advanced technology must be invented to read the full sequence and build maps of the human genome. In 1988 one re- searcher can decode between 50,000 and 100,000 bases per year. A complete sequence would need nearly 1,500 full time researchers working for a year. One problem is handling larger pieces of DNA. Genetic engineers have used bacteria and viruses to ‘amplify’ smaller sections of DNA, but this only extends to DNA fragments of up to 40,000 bases. Cloning or duplication of those pieces has improved, but to give a complete picture of the genome would require roughly 1.5 million laboratory clones. a Dr. Maynard Olsen of Washington University, St. Louis, has TWO G E nN ETIC co DES reported a technique for constructing artificial yeast chromosomes that carry 30,000 to 40,000 bases of inserted DNA. If these artificial chromosomes can be improved tenfold, the number of clones needed Scientists at the U.S. Massachusetts Institute of Technology have for a complete library would drop to a manageable size. nda a hencbthenuah Aina haw rele snlnent, Aces neste! ALMOSI 41 Numan Ceus Contam 40 chromosomes, wnicn contain our DNA. There are approximately six billion nucleotides (or bases) in the human genome and about 100,000 genes in homo sapiens, each one accounting for about 1,000 pairs of these bases. More than 95% of the genetic message, therefore, appears to be redundant - it doesn’t appear to contribute to the genes that code our life-giving proteins. More advanced technology must be invented to read the full sequence and build maps of the human genome. In 1988 one re- searcher can decode between 50,000 and 100,000 bases per year. A complete sequence would need nearly 1,500 full time researchers working for a year. One problem is handling larger pieces of DNA. Genetic engineers have used bacteria and viruses to ‘amplify’ smaller sections of DNA, but this only extends to DNA fragments of up to 40,000 bases. Cloning or duplication of those pieces has improved, but to give a complete picture of the genome would require roughly 1.5 million laboratory clones. Dr. Maynard Olsen of Washington University, St, Louis, has reported a technique for constructing artificial yeast chromosomes that carry 30,000 to 40,000 bases of inserted DNA. If these artificial chromosomes can be improved tenfold, the number of clones needed Scientists at the U.S. Massachusetts Institute of Technology have for a complete library would drop to a manageable size. made a breakthrough in understanding how cells carry out their work of translating the instructions of the genetic code. Dr. Michael Thomas of the British Medical Association's board They have found that there are two genetic codes and that the of science says gene manipulation could lead to activation of cezer- second one is far simpler than anyone had imagined it could be. It is causing genes, and even endanger the human species with too much believed to be older and more primitive than the DNA code, and dates genetic interference. Techniques in genetic engineering have devel- from billions of years ago when all life had less elaborate genetic oped so quickly that hundreds of genes have already been partly or blueprints, with fewer steps in its protein synthesis. completely cloned. With our interference, the enormous diversity in Professor of biophysics and bioche:isty, Paul Schimmel and the human genetic make-up could be disturbed. This diversity has post-graduate student Dr. Ya-Ming Hou have found that the second persisted throughout evolution to allow the survival of the species code can use as few as two elements to direct a crucial cellular when major environmental changes occur. By trying to treat and function. The primary DNA code uses four different chemical “let- eradicate disease by gene therapy and selective abortion, it’s possible ters” to spell out the thousands of genes'needed to sustain the life of to also deplete the human gene pool, making it much harder to survive a simple organism. The second code’s RNA-based binary simplicity future environmental challenges. suggests that tiny defects in the system can lead to disasters such as birth defects, spontaneous miscarriages and fatal diseases. The more complex DNA code can apparently tolerate many more mutations be- E M B RY @] T RG N AY P L a N T fore the entire system goes beserk. d N RAVE L L I N G TH E C re) D E Th breakthroughs in the US and England, doctors can now remove early embryos from their mothers, screen them for genetic diseases and put back the healthy ones. Tests were first done on Marmoset TaMarch this year a committee of senior American scientific advisers monkeys where small sections of cells were sliced off the embryo, proposed special funding for a project to unravel the genetic code of screened and returned to the marmosets’ wombs. All the embryos humans. grew into normal monkeys. Called the genome, this code contains all the inherited genetic In California Dr John Buster has successfully moved embryos information needed to make a human being. When decoded, its fertilized in one woman into the womb of another woman who gave information would fill one thousand telephone directories. The infor- birth to a healthy child. In London, Dr Marilyn Monk has recently mation in the genome is made up of a sequence of four different detected signs of an inherited disease in a single-celled embryo. chemicals called nucleotides or bases. The sequence or order of these Breakthroughs are being made - but new legislation banning bases is the important feature that distinguishes individuals and experiments on embryos is being prepared by a number of countries. species from each other. This may prevent doctors from using these new techniques, but is 24 NEXUS New Times Six - Spring 1988 Scientists at the U.S. Massachusetts Institute of Technology have made a breakthrough in understanding how cells carry out their work of translating the instructions of the genetic code. They have found that there are two genetic codes and that the second one is far simpler than anyone had imagined it could be. It is believed to be older and more primitive than the DNA code, and dates from billions of years ago when all life had less elaborate genetic blueprints, with fewer steps in its protein synthesis. Professor of biophysics and bioechemisty, Paul Schimmel and post-graduate student Dr. Ya-~-Ming Hou have found that the second code can use as few as two elements to direct a crucial cellular function. The primary DNA code uses four different chemical “let- ters” to spell out the thousands of genes needed to sustain the life of a simple organism. The second code’s RNA-based binary simplicity suggests that tiny defects in the system can lead to disasters such as birth defects, spontaneous miscarriages and fatal diseases. The more complex DNA code can apparently tolerate many more mutations be- fore the entire system goes beserk. Dr. Michael Thomas of the British Medical Association's board of science says gene manipulation could lead to activation of ceser- causing genes, and even endanger the human species with too much genetic interference. Techniques in genetic engineering have devel- oped so quickly that hundreds of genes have already been partly or completely cloned. With our interference, the enormous diversity in the human genetic make-up could be disturbed. This diversity has persisted throughout evolution to allow the survival of the species when major environmental changes occur. By trying to treat and eradicate disease by gene therapy and selective abortion, it’s possible to also deplete the human gene pool, making it much harder to survive future environmental challenges. Th breakthroughs in the US and England, doctors can now remove early embryos from their mothers, screen them for genetic diseases and put back the healthy ones. Tests were first done on Marmoset monkeys where small sections of cells were sliced off the embryo, screened and returned to the marmosets’ wombs. All the embryos grew into normal monkeys. In California Dr John Buster has successfully moved embryos fertilized in one woman into the womb of another woman who gave birth to a healthy child. In London, Dr Marilyn Monk has recently detected signs of an inherited disease in a single-celled embryo. Breakthroughs are being made - but new legislation banning experiments on embryos is being prepared by a number of countries. This may prevent doctors from using these new techniques, but is TaMarch this year a committee of senior American scientific advisers proposed special funding for a project to unravel the genetic code of humans. Called the genome, this code contains all the inherited genetic information needed to make a human being. When decoded, its information would fill one thousand telephone directories. The infor- mation in the genome is made up of a sequence of four different chemicals called nucleotides or bases. The sequence or order of these bases is the important feature that distinguishes individuals and species from each other. TWO GENETIC CODES EMBRYO TRANSPLANT UNRAVELLING THE CODE 24 NEXUS New Times Six - Spring 1988