Who would say that tiny fruit flies could be so valuable for scientific research? Somehow they have had the interest of scientists for a very long time and have greatly contributed for the advancement of science. I have been working with fruit flies for almost eight years and during this time I developed a kind of fascination for them. Fruit flies look very interesting under the microscope and very often I like to pay attention to the little details on them: they are beautiful!
But how can fruit flies be useful for medical research?
They have a lower number of genes compared to humans, making them much simpler to study. This is particularly important because it means that if we disrupt a gene in the fly, it is very likely that it will cause some sort of phenotype. In more complex organisms it is possible that other genes exist with the same functions, and therefore they may compensate for the disruption of the first gene and no phenotype is observed. Another advantage of working with fruit flies is that we can get a lot of animals in a short period of time: we can do more experiments at lower costs.
The flies I have been working with, in Miguel’s lab, have a disruption in one of the genes that can cause Parkinson’s disease in humans. The two genes we work with are PINK1 and Parkin and thanks to studies in flies we learnt that these genes are very important for the maintenance of healthy mitochondria. Mitochondria are the structures inside the cells that are responsible for the production of most of the energy necessary for keeping the cells alive and functional. PINK1 and Parkin affect the function of mitochondria, including removing the ones that become damaged and start causing problems.
The human brain is known to be very demanding of energy and this can be the reason why not having these proteins (PINK1 and Parkin) renders some brain cells susceptible to die and cause PD. In flies, the tissues that more rapidly suffer from energy deprivation are the muscles. Young flies with problems in these genes have muscle degeneration: when we test their capacity to climb on some tubes, we can see that they are much slower than the normal flies, they have less energy and their muscle tissue is dying. Here is a video showing one of us conducting a climbing assay:
Very interestingly however, when these flies age, they also lose some neurons in their brains, called dopaminergic neurons, likewise humans.
In our lab we want to understand what are the changes that happen in the flies that don’t have PINK1 or Parkin and what we can do to make them healthier. We compare the genes and the biochemical compounds in these flies with those of normal flies and try to understand what are the differences and why do they occur. We then focus on some particular processes that seem to be affected and try to make them better either by putting some new gene inside these flies or giving them compounds on their food. One example of this approach can be found here.