18 November 2011
Dr Elizabeth Duncan (Department of Biochemistry) was recently awarded a Fast Start Marsden Grant for a project on "Plastic genomes: does genome structure facilitate phenotypic plasticity". 
Animals are constantly exposed to different environments; they experience, among other things, changes in temperature, day length and food supply. These changes are all detected by the animal and, in some cases, these changing environments can affect the way an animal looks, the way it functions and the way it behaves. This flexibility in physiology that is induced by changes in the environment is called phenotypic plasticity.
This flexibility or phenotypic plasticity may be transient, where a change in the environment is sensed and an immediate and temporary change in physiology occurs, for example the decrease in metabolism that accompanies hibernation in bears. Alternatively, this flexibility can be long-lived where the animal senses a change in the environment, and this information is used to influence the long-term, perhaps even lifelong physiology of the animal. For example in humans, the environment your mother encounters when you are a fetus may determine how susceptible you are to type II diabetes and heart disease, diseases that don’t affect you until you are 40 or 50 years old!
Phenotypic plasticity is important for the survival and success of many animals. The pea aphid, which is a major crop pest, exhibits an extreme example of phenotypic plasticity. Aphids normally reproduce asexually giving birth to live young, these young are born almost ready to reproduce. This strategy is why aphids are successful pests - reproducing without sex means that they can have a lot more children quickly. But live young don’t deal well with harsh winter conditions, so when the day length shortens and temperatures drop asexual mothers give birth to young that are programmed to reproduce sexually. These females mate with males and lay fertilized eggs, which are protected from the harsh winter conditions and hatch in the spring as asexual females. So in response to the changing environment aphids make a life-long prediction about the environment they will encounter and change both their biology and behavior in response.
The environment interacting with our DNA brings about all these biological changes. But how does this happen? How does an environmental stimulus influence biology? And perhaps most importantly, how are these changes maintained over long periods of time? My research aims to use the extreme example of phenotypic plasticity seen in the pea aphid to answer these questions. 
We know that changes in physiology are accompanied by widespread changes in gene-expression and we propose that these changes are facilitated by the way the DNA is organized within the cell. We are going to determine whether the way the DNA is organized in sexual and asexual pea aphids, alters in response to the changing environment. We hope what we discover in aphids will give us insight into how DNA responds to the environment in other animals, including humans.
