Learning to fly

For the love of flies

Being interested in systems developmental biology, one soon comes to the problem of choosing a study subject, that is, an organism to be used in every experimental manipulation to be undertaken as part of a PhD thesis. Certain conditions that the subject has to meet are: low cost, enough experimental flexibility to manipulate biological processes through genetically engineered mutants, and the possibility to allow one testing multiple hypothesis experimentally within a timeframe compatible with the time available in a PhD thesis. Also, as important seems a preexisting accumulation of knowledge that is a pre-requisite to do systems biology. This is the case since in a sense systems biology starts where other disciplines end—it needs the basic knowledge of other fields to formulate hypotheses and models. Only very few species of multicellular organisms provide such wonders. Among the possible few choices my favorite is the fly Drosophila melanogaster, being very closely followed by the nematode Caenorhabditis elegans. The fruit fly—which given its feeding habits should better be called the yeast-fly—was chosen about 100 years ago as a model to study heredity and was popularized by T.H. Morgan at Columbia University. Morgan was awarded the Nobel Prize in medicine and physiology in 1933 for his discoveries on the role the chromosomes in heredity. Over a century the compendium of knowledge has grown so large that entire encyclopedias containing the biology of the fly exist and include information about almost every detail of its biology and its body at every life stage. These references become the first steps to be followed by any fly-researcher apprentice.

To outsiders how the fly specifies the position and number of bristles (hair-like structures present throughout its body), or filming how male sperm compete for unfertilized eggs inside the female might seem irrelevant and superfluous. Many—like a certain politician whose name we don’t want to remember—would find this kind of knowledge useless and esoteric, considering it wasteful government spending. But in reality the fly has been an important tool to understand basic biological phenomena relevant to human biology and health. For example, important cell surface receptors and proteins associated with cancer were discovered in fly genetic screens.

Recently, there is a renewed interest amongst several fly labs in using the fly to screen for small molecules that will be tested later in clinical trials as candidates for human drugs. The reason for this renewed interest lies in the fact that even though the mouse is evolutionarily closely related to us, research with mice is slow due to a longer generation time required for individuals to reach adulthood. Also, transgenics are extremely expensive to obtain and experiments are subject to much more control by ethics panels, making every aspect of research more difficult. The fly shares enough with us to make it useful for understanding human biology. Also, since compared to mice it is cheaper to maintain in colonies, since it more easily subject to genetic manipulation, and since (fortunately) animal-right’s people and ethics committees still do not advocate for a tightly regulated use if it, the fly remains as a very popular model to study many phenomena relevant to human health and disease.

Flying in the windy city

Recently, as a new comer into the fly world, I had the opportunity to attend my first fly meeting. This is how “fly people” (this is how researchers studying flies refer to themselves) call this incredible event. The meeting is hosted by the Genetics Society of America (GSA), and is the largest conference in the world entirely dedicated to flies. This year it had a couple thousands of participants: researchers from every corner of the world came to the windy city “to fly” for four days. During poster sessions that prolonged until midnight the research-crowd dispersed into halls filled with hundreds of posters. People from many nationalities clustered into small groups that, despite any possible existing language barrier, always tried to figure out the details of each other’s research.

Besides posters, during the conference new studies were presented in short and plenary session talks given by lab heads, post-docs and graduate students. Personally, I found it fascinating to meet in person some of the authors of the papers that have served as the basis for my own research. But even more exciting was the possibility to listen to talks about nearly every domain of fly biology over four days.

Flying Systems

This year the fly meeting had a new platform session dedicated to Systems Biology. Stanislav Shvartsman (Princeton) and David Arnosti (Michigan State U.) organized the platform, selecting topics like measuring and modeling specific metabolic pathways, morphogen gradients, robustness of eye patterning, and studies on molecular nets patterning the early embryo that compared different insect species.

In May of 2012 a new meeting organized by the European Science Foundation will take place in Poland. The meeting will be entirely dedicated to systems biology studies of fly development. Both the inclusion of a systems biology platform in the fly meeting, and a new conference dedicated entirely to developmental systems biology highlight how the fly research community is becoming part of the new systems adventure. Experimental studies on this emerging discipline are most advanced in prokaryotes and unicellular eukaryotes such as yeast. Even though such organisms might exhibit population coherent behaviors, due to their unicellular nature they can’t help us understand muticellular phenomena. Thus, perhaps the greatest contribution the fly can make to systems biology is to serve as a role model for the study of development and multicellularity. Being complex enough and similar to us, but not as complex and expensive as a mouse, the fly is a sweet spot to study multicellular molecular systems under normal or pathological circumstances, scenarios that are most relevant to human health and disease. The fly still has a lot to offer to the XXI biology.

— Nicolas Pelaez