Amazing biology
By Dr Atta-ur-Rahman

Part - I

There are truly amazing developments occurring in the field of biology. All information related to the biological functions of living plants or animals is encoded in their respective DNA. The DNA resides in the nucleus and it is made up of four types of bases. There are about three billion such bases arranged in the form of a double helix, and it is the sequence of these bases that determines the characteristics of living organisms.

Think of it as a long intertwined double stranded necklace with some 3 billion beads in 4 colours (4 types of bases). In our case the colour of our skin or eyes, our height, the structure of our heart and brain – in fact every single aspect of our body – is determined by this sequence. The human genome was first announced by Bill Clinton in 2003. The 13-year international effort was undertaken under a $3 billion project led by the US Department of Energy and the National Institute of Health that began in 1990 and was completed on 14 April 2003, when the sequence of the three billion ‘letters’ (bases) present in the human being’s DNA was finally announced.

The effort cost about $1 billion and took many years to complete. Today we can determine the entire sequence of the human genome at a cost of about $5,000 and carry out the sequencing within a few days. New faster technologies are being developed that should allow this to be done within 15 minutes at a cost of less than $100 !

On May 20, 2010, Craig Venter and his colleagues announced that they had succeeded in creating a living cell that was completely synthetic. They used a computer to design artificial DNA. This design was then used in the laboratory to join the building blocks together into a loop which comprised a million units of nucleic acids hooked together. When this was inserted into an empty cell, the synthetic genome took control of the cell and could produce over a billion copies of the cell.

The ability to reproduce is a key criterion of a living organism. Now that scientists have succeeded in making a synthetic genome, the next steps would be to use these tiny cells as work horses and engineer them so that they can make biofuels, pharmaceuticals and enzymes, as may be required. A new era has begun.

With the growing understanding of genomics, scientists are now trying to understand the process of ageing and how it could be slowed down. Average life expectancies have increased significantly during the last 60 years due to better hygiene and medications, though they still vary considerably from country to country. For instance the average life expectancy in Japan is about 82 years while in many African countries it is below 50 years.

Can we somehow slow down or even reverse the ageing process and prolong lifespans? This question has attracted the attention and efforts of many biologists, geneticists, medicinal chemists and biochemists. About 50-70 billion cells die each day in adult human beings, by a process of programmed cell death built into the structure of each cell (“apoptosis”) and many are replaced by new cells.

In children between the ages of 8 and 14, about 20-30 billion cells die every day and even more are replaced by new cells, thereby contributing to their growth. Indeed over a period of a year this amounts to replacement of cells in children which are about the body weight of the child!

We are now beginning to understand the underlying chemical signalling processes that tell cells to stop multiplying and die. By appropriate interventions in this process of cell death, it is possible to induce cells to live longer, thereby resulting in longer life spans. New drugs are under development with anti-ageing properties, so that we may live longer, healthier lives.

With the rapid advances in medicinal chemistry, biochemistry and genomics, scientists are beginning to understand the mechanisms by which the ageing process occurs and the features of the biological clock that is ticking within us. This understanding is also emerging from research on bacteria, spiders, insects, mice and other animals since there is an inherent similarity between the processes by which cells live, grow older and die in various living animals.

A number of compounds have been discovered which seem to slow down or even reverse the ageing process. A research group at the Harvard Medical School found that a compound ‘resveratrol’ found in a number of plants can actually prolong ageing in obese mice and reverse the process of ageing, making them younger.

When fed with resveratrol supplements, the mice showed dramatic improvements in their health indicators. Their arteries became cleaner, hearts stronger and brain functions improved. This happened due to the accelerated production of an enzyme SIRT1 that has been known to be involved in the prevention and treatment of age related diseases.

Researchers at the Salk Institute for Biological Studies and the University of California, Los Angeles recently discovered that modifying a gene (dPGC-1) that occurs in the intestinal stem cells of the fruit fly can prolong the average lifespan of the fruit fly itself by 50 percent! Thus genetic modifications can extend the lifespan of the insect. This gene is also found in humans. Indeed Swedish scientists in 2011 had discovered the enzyme responsible for the fact that eating less leads to longer lives in human beings (Molecular Cell, September 2, 2011).

Oxygen, so necessary for the survival of life, is also involved in the ageing process. A reactive form of oxygen (oxygen radicals) attacks our DNA and contributes to its degradation and ageing. That is why anti-oxidants such as Vitamin C, which counter the effects of this reactive oxygen, are thought to be good for our health.

The Jamilur Rahman Centre for Genomics Research has been established at the Karachi University. Named after my father, it is a result of a personal donation from me. A high-speed gene sequencer and other equipment have been imported and installed and the genetic make-up of different population groups is being studied. The centre will also be involved in the field of biosaline agriculture so that modified edible crops that can be grown using sea water can be developed.

Access to water, and hence to food, is going to be the single biggest challenge for the world over the next 30 years as our earth suffers from the increasingly deleterious effects of global warming that will cause droughts and desertification. Pakistan needs to prepare itself for such challenges through scientific research.

To be concluded

The writer is the president of the Pakistan Academy of Sciences and former chairman of the HEC.

Email: ibne_sina@hotmail.com