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Fruit flies serve as an important model used in modern genetic research. (http://www.ens.gu.edu/) [Click to enlarge]

The fly is useful because of its small size and reproductive capabilities. (http://www.byc.com.au/) [Click to enlarge]

A legion of researchers, lead by Johns Hopkins University's Joel S.Bader, have assembled a protein interaction map for Drosophilamelanogaster (the fruit fly), which details the interactions between roughly 10,000 proteins in its cells. This landmark achievement paves the way for a greater understanding of how genetic changes effect organisms as well as enabling the development of new drug candidates to treat disease.

The fruit fly is the subject of study for many scientists. The adult fly is about an eighth of an inch long including wings with red eyes and tan colored abdomen and thorax. They are attracted mostly to fresh and fermenting fruits and vegetables.

These flies are attracted to light and become sexually active two days after they emerge from the pupae stage. They mate more than once and deposit an egg mass of about 500 eggs on or near a food source. Fruit flies undergo complete metamorphosis. The eggs emerge in approximately 30 hours. The larvae feed on organic material for several days then pupate. The entire life cycle can be complete in eight days, so once established it is not hard to figure out how rapidly they multiply.

Drosophila has been used as a model organism for research for almost a century, and today. Its importance for human health was recognized by the award of the Nobel prize in medicine/physiology to Ed Lewis, Christiane Nusslein-Volhard and Eric Wieschaus in 1995.

The Drosophila protein interaction map, published last week in Science, is the first of its kind for a multicellular organism. Previously these types of maps existed only for single-cell organisms such as Saccharomyces Cerevisiae or common bread yeast.

 In a JHU press release Bader, an associate professor of the Department of Biomedical Engineering, said that previous research, which had yielded data about with genes in the organism coded for certain proteins, was "like having a biological "parts' list. But what we haven't known is how these parts are connected to one another. We haven't had the equivalent of a wiring diagram or an assembly manual. What this new map does is tell us which proteins "talk' to one another and work together within the cell."

The map is the product of several years of research which began while Bader was employed as the head of bioinformatics at the New Haven, Conn. biotech company CuraGen Corp.

Bader continued his work on the project after he joined the faculty in August of this year and is listed as one of the three principal authors of the article in Science. Bader and the over 36 researchers who collaborated with him on this project chose Drosophila for the project because it has a surprisingly high genetic similarity to humans.

The fruit fly is also a useful research organism because of its small size and the roughly two weeks that it takes for one generation of flies to be born and mature.

Utilizing a method known as the "two-hybrid method," which involved combining two yeast cells, one expressing a single fruit fly protein and the other expressing over 10,000, yielded data about which of these proteins interacted.

With 10,000 repetitions of the experiment necessary to generate the protein interaction map gives one an idea of why the time span of the research was several years long.

Combined with knowledge amassed concerning what genetic sequences code for which proteins this map will allow researchers to understand better how the changes on the genetic level of an organism effect the proteins to produce disease.

"It's not enough to know which parts make up a human cell," Bader said in the same press release, "you have to know which parts work together to carry out particular functions within the cell.

This will lead to a better understanding of genetic diseases, and it will add to our knowledge of basic biology, our understanding of how cells work."

Bader's main role in the experiment was in the organization of the data into a usable whole through the use of computer software; his specialty is in computational biology.

The data gleaned from the experiment has be entered into an online database, called Flynet.

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