The use of animal models in research has benefited the area of science greatly; they have allowed us to generate cures and treatments for many diseases, in addition to helping us understand the genetic and physiological effects of harmful stimuli. However there is still an ongoing debate as to whether using animal models in research actually yields valuable results (Pound et al, 2004). Read the rest of this entry »
My interest in the art of medicine manifested itself from a childhood fascination into the workings of the human body. This fascination gradually developed into a passion for science and led me to undertake a degree in genetics. Throughout my degree I have found the rapid developments in the area of genetics and their implications in the world of medicine captivating. Read the rest of this entry »
This question is very difficult to prove, but theories have been postulated which attempt to explain why evolvability is a selectable trait. The difficulty surrounding selection and evolvability is that evolvability is a trait of lineages as opposed to individuals and this is where the difficulty regarding selection comes in.
The ability of viral and bacterial pathogens to develop antibiotic resistance is a combination of natural selection and evolvability. The application of antibiotics to bacterial populations places them under a stressful environment. Bacteria and viruses are prokaryotes and therefore a lot of their genetic material is composed of RNA. RNA is genomically unstable and has a much higher mutation rate than DNA.
During the early 1990’s scientists were more concerned about the actual resultant variation from Darwinian evolution, rather than its origin. Many scientists assumed that the origin of the variation was a product of Darwinian evolution. But recent evidence from simulations and observations of simple evolutionary systems has yielded results which prove that this is not the case (Nehaniv, 2003).
Kimura (1983) is one of the key players of research into genetic neutrality and had a major role in its rise to prominence. Kimura referred to neutrality as genetic variation that does not result in change to the fitness of an organism. Moreover any change has to remain neutral in any environmental, genetic or physical condition.
Robust biological systems acquire less phenotypic variation through environmental stressors or genetic damage as compared to less robust systems (Wagner, 2005). The ability of organisms to balance robustness and evolvability is the key for surviving a billion generations of varying environmental conditions with high levels of consistency (Lenski et al, 2006).
Evolvability is recognised as the ability of an organism of any particular lineage to develop heritable phenotypic variation (Kirschner, 1998). Darwin’s theory of evolution is fundamental to Evolvability, as it is evolution which allows for the development of this heritable phenotypic variation. This variation could stem from natural selection or it could be from the result of acquired genetic change functions which can lead to novel functions.
Werner syndrome is one of the best studies progeriod syndromes. It is considered an excellent model for human ageing (Cheng et al, 2007). Patients with Werner syndrome exhibit accelerated ageing and the common phenotypes associated with ageing. In this disease the WRN gene is mutated mainly through chromosomal translocations and this results in the production of a dysfunctional WRN protein (which has multiple roles in DNA metabolism).
McCay et al first provided evidence in 1935 to suggest that caloric restriction slows down the ageing process and that it could potentially increase life span. Research has since expanded and yielded exciting results in many organisms which back up this concept. Bodkin et al (1995) enforced long term caloric restriction on adult male rhesus monkeys. The research group noted that the mortality rate in the control groups was higher than in the dietary restricted group. It can be seen that caloric restriction leads to changes in physiological changes that have the eventual effect of increasing longevity. (Guarente, 2005)
