More than two years ago, Pietra "Petey" Bruni adopted her "children."

She watched them closely, fed them on regular schedules and even woke up at 2 a.m. sometimes to check on them.

Bruni's children, P. fusiformis and P. lunula, needed her attention day and night.

The 15-year-old Seton-La Salle freshman bested 64 other competitors with her experiment, "Glow with the Flow: Year 2," to win first place in the senior biology division of the 69th Pittsburgh Regional Science and Engineering Fair.

Her experiment exposed P. fusiformis and P. lunula -- forms of photosynthetic marine plankton -- to fluorescent light during their "light" and "dark" phases. The procedure can be likened to waking up a human to eat in the middle of the night. Bruni wanted to see how feeding plankton light two hours into their night cycles -- the equivalent of the deep sleep stage for humans -- would affect their ability to feed during daylight cycles.

"They are so much like little humans," Bruni said of the plankton. "They have circadian rhythms, just like we do."

The jet-lag inducing inner-clock humans have is probably where the similarities end with microscopic marine creatures. But that didn't stop Bruni from sympathizing with her test subjects.

"It sounds really mean," Bruni said. "I take these dinoflagellates and put them in all these bad situations."

Dinoflagellates is the scientific word for Bruni's plankton. She is fluent in biology speak -- a complex language of Latin names and three- or four-syllable verbs.

"I just understand what these things are," said Angela Bruni, Petey's mother, referring to the plankton. "I don't understand what she does."

What Bruni discovered, put simply, was exposure to light during the dark phase resulted in the planktons' inability to absorb light during the "daylight" phase.

This discovery builds off of last year's experiment, when Bruni controlled the plankton's "daylight" and "night" phases. She exposed four groups of the organisms to differing durations of light -- six, 12, 18 and 24 hours. The group exposed to six and 18 hours performed the best because they were the closest durations to the organism's phases in the wild.

Last year's experiment also won first place, but in the Intermediate division because she was an eighth grader attending St. Thomas More at the time. The win was her third in as many tries at the Pittsburgh regional fair.

"She's the new guru of the biology part of the science fair," Bruni's mother said.

Bruni developed her appreciation for the plankton while attending a marine biology camp in Wallops Island, Va., two summers ago.

She returned home from the camp with a curiosity about the tiny organisms, capable of glowing briefly when properly agitated. After some research, she decided to make it her experiment subject for the coming school year.

Bruni contacted Dr. Edith Widder, of the Harbor Branch Oceanographic Institute in Florida, about advising her on the experiment. Widder declined due to time constraints, but referred her to Dr. Jan Rines and Dr. James Sullivan, professors at the University of Rhode Island and marine biologists.

They helped scale back her initial experiment plans, which was to do this year and last year's test at the same time.

Bruni worked with Dr. Michael Latz this year. Latz heads the Latz Laboratory at the Scripps Institute of Oceanography in La Jolla, Calif. Latz, one of the field's foremost researchers, required Bruni to send her entire project before he agreed to advise her.

"He wanted to make sure I was serious about this," Bruni said.

With several researchers in her corner and a slew of wins at major science fairs, Bruni seems poised to go on to great things.

She is years away from college, but two -- Carlow and Waynesburg University -- have already awarded her thousands of dollars in four-year scholarships. Bruni would rather go northeast, to Brown University or the University of Rhode Island. The University of Pittsburgh and Carnegie Mellon University are her local favorites.

In the immediate future, Bruni hopes to develop her experiment further next year. She wants to "mechanically stimulate" the plankton, which will produce differing levels of glow.

But what of the P. fusiformis and P. lunula she spent months tending to?

"They're still living in my basement," Bruni said.