You usually see fruit flies hovering over or landing on fermented fruit-not heading for outer space.

But that's just what fruit flies studied by genetics researcher and NASA investigator Deborah Kimbrell of the University of California, Davis will do when the space shuttle Discovery blasts off on its next mission.

The shuttle, targeted to lift off at the Kennedy Space Center sometime between July 1 and July 19, will carry a five-man, two-woman crew-and 10 containers of fruit flies and a small container of a fungus.

Her research, the first of its kind, will study the effect of space on the immune functions of the common fruit fly, Drosophila melanogaster. Following the 12-day mission, she and her collaborators will infect the fruit flies with fungus and bacteria to detect their immune responses. Previous experiments showed that fruit flies can survive in space.

Kimbrell and a contingent of family, friends and fellow scientists will meet at the Florida space center to cheer the launch. The real work begins after the shuttle lands. Kimbrell and her collaborators will spend five weeks in a specially set-up lab at the space center to test the immune functions of the infected "astronaut" fruit flies, comparing them with infected "ground-based" fruit flies.

"The findings can be used to determine how space affects the human immune system," she said, noting that the human and the fruit fly immune systems are quite similar. The fruit fly, or "the golden bug," is a prized tool for genetic research and developmental studies.

Kimbrell, an associate research geneticist in the Section of Molecular and Cellular Biology, College of Biological Sciences, specializes in studying fruit fly genes that control immune responses and how gravity affects them.

Her space research is an extension of her NASA research grant, "Drosophila as a Model of Immune Function in Conditions of Altered Gravitational Force," awarded in 2004.

The fruit flies will be housed in 10 small flat containers during the 12-day mission, and will be fed once. Kimbrell expects to see many of them survive the flight, and to yield a second generation within 10 days.

"Only a handful of male and female flies will go up in each container," she said. "The big question is how many of their progeny will survive the spaceflight and return to earth. I hope they stay healthy."

The fungus on board is Beauveria bassiana, a natural soil-borne fungus sold commercially as an organic pesticide. It feeds on and destroys an insect's internal organs but is not harmful to humans, she said.

Kimbrell's experiments will center on fruit flies reared on the ground; fruit flies hatched on Earth and hurdled into space; and flies born reared in space. She hopes the experiment will answer such questions as:

. What is the genetic response to infection after spaceflight?
. Will the fungus become more virulent or pathogenic after spaceflight?

Kimbrell hypothesizes that the immune systems of spaceflight fruit flies will not function as well as those of their earthly counterparts. She also speculates that the spaceflight fungus will be more virulent than typical fungus.

The spaceflight experiment will mesh her two passions, space and fruit flies. Born at Goodfellow Air Force Base, Texas, she grew up in an Air Force family. Her father, Billy, a master sergeant who served in Vietnam and Korea, is a space enthusiast. Her brother, Steve, became an aeronautics engineer. Her husband, Ingemar Olsson, is a private pilot.

And Drosophila? The red-eyed, black-tipped abdomen insect that's less than an eighth of an inch long?

" I first saw Drosophila through a dissecting microscope when I was a graduate student," said Kimbrell, who received her doctorate in genetics at UC Berkeley after graduating from Mills College, Oakland. "It was love at first sight."

Post-doctorate fellowships took her to Cambridge University, England and to the University of Stockholm, Sweden. At Stockholm, she participated in pioneering research that led to the establishment of the fruit fly as the common model for studying the effect on genes, similar to humans, when infected with different types of bacteria and fungus.

That was in the 1980s. Now a leading scientist in her field, she lectures at Drosophila conferences in France, Italy and Japan and the United States.

"Drosophila," she said, "is in an interesting position as a research organism. Its utility spans from being a model organism for other insects all the way to humans. Drosophila also is useful in many areas, such as studies on pesticides and hormonal regulation of development."

The fruit fly continues to fascinate her. "It has a negative geotaxis (movement away from the direction of gravity)," she said. "When I turn a flask of fruit flies upside down, look what happens--the flies swarm from the bottom to the top."

Before joining UC Davis in 1999, she served as a senior research fellow at Rice University, Houston, Texas. "Houston, we have lift-off!" rings in her memory.

Meanwhile, the UC Davis scientist is looking forward to the launch and working with her collaborators, from the NASA Ames Research Center, University of Central Florida, UC Davis' Chronic Acceleration Research Unit, Rice University and the University of Nevada-Las Vegas.

And what do folks think when they learn her fruit flies are going into space?

"People's faces light up and after a short pause, they start asking questions," she said. "The thought of little fruit flies going up in space engages people's imagination and a sense of fun. Drosophila generates scientific curiosity and amusement."

Deborah Kimbrell just wishes she could go, too.