Hot on the heels of the announcement of her first runner-up award in the 'Distinguished Young Woman in the Life, Natural and Engineering Sciences' category of the 2011 South African Women in Science Awards (WISA), Professor Janice Limson presented a lecture at Eden Grove as the recipient of the Vice-Chancellor’s Distinguished Research Award for 2010.

Entitled ‘Ageing, Sex, Death (and Heavy Metals), the lecture provided an overview of her field. With her ten-member strong research group, Prof Limson works in the field of Biotechnology, at what has been described as the interface of nanotechnology, biology and chemistry.

Her research focuses on the design and development of biosensors, which can be engineered to detect diseases such as cancer and malaria in their very early stages. Biosensors can also be utilised to monitor toxic environmental pollutants and to identify beneficial compounds in plants.

Prof Limson opened her talk by asking what is ageing? The safe answer is that it is the manifestation of biological events which occur over a span of time; however, this does not clarify what causes it. Theories include genetic programming, allowing our cells a finite number of divisions before cell death occurs.

Another cause of ageing can be attributed to free radicals, molecules which have lost an electron, and which are desperately trying to grab another from other molecules. This leads to an ‘unzipping’ effect for example of cell membranes, cell damage and to cell death.

Then there is Aristotle’s theory – that each sex act brings us closer to death.

While this is a far-fetched idea, and has never been proven true, there is, as Prof Limson explained, a growing body of scientists who believe that there is a link between fertility and longevity, with low fertility being linked to increased lifespan.

This theory suggests that the energy that would have been expended on the reproductive process has instead been spent on the less protected soma cells of the body, giving them increased protection. Additionally, different people have differing abilities to cope with the cell damage which results in ageing and disease, while lifestyle and good old-fashioned luck also play a role.

Referring back to the title of the lecture, Prof Limson described metals as being a predominant cause of free radicals. Our bodies have evolved relationships with metals; manganese, zinc and iron, for example, which are essential, whereas we have no basis in our bodies for lead, arsenic, aluminium and cadmium, although we have evolved methods to eject these from our bodies, or to limit their damage.    

Our bodies have developed defense mechanisms to deal with the development of free radicals. Known as antioxidants, these include naturally produced enzymes and hormones such as melatonin, and then those which we consume from our diets such as vitamins C and E, and compounds such as resveratrol, from grapes. Antioxidants can serve to protect against free radical damage by donating an electron to free radicals  or in other ways such as by binding and “inactivating” certain metals which could generate free radicals.

Prof Limson and her research group have worked on studies to understand how the body protects itself from free radical damage and have thus been studying and identifying new potential antioxidants from sources such as plants, vegetables and even algae.

Biosensors may be the answer to the question as to how cells can be protected from free radicals, and how disease can be detected sufficiently early for treatment to be effective.

With South Africa’s decentralized medical care and current socio-economic framework, not to mention the chronic diseases so prevalent within the country, biosensor research is a necessity, and the resources of the DST/Mintek Nanotechnology Innovation Centre are enabling Prof Limson’s research group to work on developing sensors for the fast detection of malaria and breast cancer.

In the future Prof Limson hopes that ‘seek and destroy’ sensors can be developed, which will not only locate disease but carry a means of destroying it.

By Jeannie McKeown

Picture: Sophie Smith