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| Wednesday, 24 November 2004 |
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Reading the Book of Life through the Human Genome Project - Part 11 Continued from November 19 Excerpts from the Plenary lecture delivered at the joint academic sessions of the Faculty of Science and the Faculty of Medicine, University of Colombo by Professor Eric H Karunanayake, Director, Institute of Biochemistry, Molecular Biology & Biotechnology, University of Colombo. The previous studies which showed that our genes are split, that is a gene is interrupted with coding sequences (exons) and non-coding sequences (introns) were further proved by the genome sequence. The sequence also reveals our own evolution and therefore strengthens the study of evolutionary molecular biology. For example, it is now scientifically proved that all human beings, irrespective of the colour of the skin, or the geographical location, are 99.9 percent identical genetically and differs only by 0.1 percent. It is also now well established with scientific data that human population originated in Africa, and then migrated to the different parts of the globe. Malarial parasite The availability of entire genome sequence of the human being provides unprecedented avenues for studying the molecular basis of disease, the development precise diagnostic techniques, the identification of genes that predisposes to the development of disease in late life and therefore provision to provide preventive measures, and the development of novel drugs specifically designed to correct the molecular leision. Thus the practice of medicine at molecular level has been born. It also raises several ethical, legal and societal implications. Along with the completion of the human genome many other genomes have been completely sequenced. These data are now available in the public domain. These include among many others, the genome sequence of the malarial parasite, Plasmodium falciparum, the tuberculosis causing bacterium, Mycobacterium tuberculosis, the SARS virus sequence, the genome of the filarial parasite, Brugia malayi, the genome of the Malaria transmitting mosquito in Africa, Anopheles gambiae, and hundreds of many other genomes relevant to improve quality of our life. The plant molecular biologists at the same time took the initiative to sequence plant genomes. The genome of the wild mustard, Arabidopsis thaliana, and rice are now available in the public domain. What does this vast amount of data mean to mankind? What can we do with this ? The 21st Century will witness, at least those who are young today, unimaginable developments in the diagnosis of diseases, treatment, and prevention of disease. It is predicted that just as much as one could carry in his/her wallet the name of the blood group, by 2025 each person would carry (at least in the advanced countries) a chip of his/her genome sequence in the wallet. The physician will have his computer linked to international/national data bases. The diagnosis and individualized treatment will then be decided on the analysis and interpretation of his/her genomic data and the illness affecting the patient. Vaccinations success Vaccination against infectious diseases has been one of the most successful programmes, such as eradication of smallpox, the prevention of polio, and tuberculosis to cite some examples. However, these programmes have not yielded the expected results in the developing countries. These failures have been attributed to among others, to the poor infrastructure in the healthcare delivery systems and corruption rampant in these countries. In order to overcome these drawbacks, the World Health Organization and many other funding organizations are now encouraging the development of edible vaccines. The edible vaccines are those which can be incorporated into stable diets of populations affected by a given disease. For example, if a protein with vaccine potential can be incorporated into banana or manioc which is a staple diet in Africa where malaria is endemic, this will certainly prevent millions of deaths in Africa. The route to such a vaccine is the introduction of gene into the plant genome where it will produce the protein. The next problem to solve is that proteins are digested in our alimentary canal to component amino acids. Therefore the research is required to ensure that this protein of vaccine potential is not digested in the alimentary canal. Although even a conventional vaccine is not yet available against malaria, despite extensive research in this area, research effort is now in progress towards the development of edible vaccines. Another disease, causing millions of deaths in Africa, but is also a global disease, AIDS, caused by the Human Immunodeficiency Virus (HIV), is attracting millions of dollars to initiate research towards the development of a vaccine. Two decades ago any scientist, even suggesting such an approach would have been considered a lunatic. The advances in molecular genetics, molecular biology, biochemistry, and physiology during the last two decades, which is now justifiably identified as molecular life sciences, hold the hope for millions of people, particularly in developing countries, suffering from these life threatening diseases. Cancer mortality Cancer is the cause of highest mortality in USA followed by cardiovascular diseases and diabetes. The latest problem of the west is obesity, which predisposes to cardiovascular diseases and diabetes. Until quite recent times these diseases were considered as diseases of the affluent societies. This scenario is gradually changing. The population in developing countries, perhaps as a result of globalization, open economy, loss or ignorance of traditional systems of nutrition, preventive measures, is gradually getting engulfed with the diseases of the west. Cancer is caused by the uncontrolled proliferation of an abnormal cell in our body, which ultimately produce a malignant tumor. An adult human body consists of more than 200 different types of cells and an approximate total of 3 trillion cells. This cellular composition is maintained during our life by division of cells to produce daughter progenies with identical genetic composition, a process known as cell cycle or division. This is tightly regulated biochemical process. The human body is therefore of massive complexity. Yet there are in built mechanisms arisen during our long history of evolution to ensure that this complexity is protected. Our genome, DNA in the chromosomes, is subjected to constant damage by radiation, UV light a component of sunlight, and large number of environmental pollutants including food additives. When such damage has occurred which could be fatal or could be the cause of disease, there are genetic mechanisms by which such aberrant cells could be identified and condemned to death, a process called programmed cell death or apoptosis. This will eliminate this abnormal cell, a potential tumorogenic cell. This elimination process or apoptosis is carried out by a large number of proteins which are encoded in our genome. Thus if damage has been incurred on these genes, the guardians of the genome, by the earlier described tumorogenic agents, then the process of condemned cell death will fail and the abnormal cell will proliferate in an exponential manner leading to a malignant tumor. The finger printing is an age old technique used for the identification of individuals either for administrative, legal or forensic purposes. For example, even today in many countries, the finger print is used as a substitute for signature, for those who are unable to sign or to identify a criminal. The most advanced country in the world, USA, now uses finger printing to issue a visiting Visa to USA. The advent of molecular sciences replaced classical finger printing with DNA finger printing. This is because despite the fact we homo sapiens are 99.9 percent identical, the difference of 0.1 percent is unique to individuals except in the case of identical twins. The DNA finger printing was developed by Alec Jeffreys in UK and it was an accidental observation. The advantage of DNA finger printing is that a tiny drop of blood or semen or a hair follicle left at the site of the crime can be used to accurately identify the ... (Concluded) |
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