Predators and prey in a Petri dish
Duke University scientists, in collaboration with colleagues from Stanford University, Howard Hughes Medical Institute and the California Institute of Technology, working under the leadership of Dr. Lingchong Yu, have developed a living system of genetically modified bacteria that will allow for a more detailed study of predator-prey interactions at the population level.
The new experimental model is an example of an artificial ecosystem, for which researchers program bacteria to perform new functions. Such reprogrammed bacteria can be widely used in medicine, environmental cleaning and the creation of biocomputers. As part of this work, scientists rewrote the "software" of Escherichia coli in such a way that two different bacterial populations formed a typical predator-prey interaction system in laboratory conditions, the peculiarity of which was that the bacteria did not devour each other, but controlled the size of the opponent population by changing the frequency of "suicides".
The field of research known as synthetic biology emerged around 2000, and most of the systems created since then are based on the reprogramming of a single bacterium. The model developed by the authors is unique in that it consists of two bacterial populations living in the same ecosystem, whose survival depends on each other.
The key to the successful functioning of such a system is the ability of two populations to interact with each other. The authors created two strains of bacteria – "predators" and "herbivores", depending on the situation, releasing toxic or protective compounds into the general ecosystem.
The principle of operation of the system is based on maintaining the ratio of the number of predators and victims in a regulated environment. Changes in the number of cells in one of the populations activate reprogrammed genes, which triggers the synthesis of certain chemical compounds.
Thus, a small number of victims in the environment causes the activation of the self-destruction gene in predator cells and their death. However, as the number of victims increases, the compound released by them into the environment reaches a critical concentration and activates the predator gene, which provides the synthesis of an "antidote" to the suicidal gene. This leads to an increase in the predator population, which, in turn, leads to the accumulation of a compound synthesized by predators in the environment, pushing victims to suicide.
Using fluorescence microscopy, scientists documented interactions between predators and prey.
Predator cells colored green cause suicide of victim cells colored red. Elongation and rupture of the victim cell indicates its death.
This system is not an accurate representation of predator-prey interactions in nature, because predator bacteria do not feed on prey bacteria and both populations compete for the same food resources. However, the authors believe that the system they have developed is a useful tool for biological research.
The new system demonstrates a clear relationship between genetics and population dynamics, which in the future will help in studying the influence of molecular interactions on population changes, which are the central theme of ecology. The system provides virtually unlimited possibilities for changing variables to study in detail the interactions between the environment, gene regulation and population dynamics.
The authors claim that with the help of additional methods of controlling the properties of different populations, they will be able to reprogram bacteria in such a way that their use will allow simulating the processes of development and interaction of more complex organisms.
Portal "Eternal youth" www.vechnayamolodost.ru based on EurekAlert materials
15.04.2008