Zebrafish
Morning is feeding time in the lab of Rhode Island College Assistant Professor Larissa Patterson. The first in line are aquatic animals so tiny they’re only visible under a microscope. They’re called rotifers.
Though rotifers are not this lab’s subject of research, they serve an important purpose. Not only are they harvested to feed the lab’s model organism – zebrafish – rotifers can really tidy up a fish tank, clearing it of waste. Their outer coats are covered with spines or spikes, with a ring of cilia (hairs) at their head end. Beating their cilia, they suck algae, dead bacteria and protozoa into their stomachs.
Rotifers as seen under a microscope
This morning, one of Patterson’s research students, Jeni Melo, empties a liter of rotifers into a beaker of algae (what looks like a green drink), where they dine for about a half an hour. Then she carries them down a long corridor.
Unlocking a metal door, she heaves it open and enters another room. The environment here is tranquil. The only sounds are the white noise of gurgling water and the rhythmic pumping of fish tank filters. Housed in two tanks are zebrafish, slowly drifting back and forth behind glass walls, both observing and being observed. Five horizontal blue stripes pattern the sides of their bodies.
A developmental biologist, Patterson is studying zebrafish stripes. “These stripes,” she said, “are actually thousands of individual pigment cells that migrate across the body of the fish during its early embryonic stage. The cells then organize into stripes at specific locations on the body.”
“But sometimes something goes wrong with a gene and black pigment cells called melanocytes migrate at the wrong time or to the wrong location,” she said. “In humans, uncontrolled cell division and aberrant migration of melanocytes can lead to melanoma, a highly dangerous form of skin cancer.”
By identifying the genes that control pigment cell migration in zebrafish, Patterson and her research team hope to learn more about the development of human melanoma.
Genetically, zebrafish share 70 percent of the same genes as humans and 84 percent of human genes known to be associated with human disease.
However, zebrafish differ from humans in the way they give birth. When zebrafish spawn, the female releases eggs that drop to the bottom of the tank, while the males release sperm that fertilize the eggs. The embryos collect at the bottom of the fish tank to develop outside the mother’s body. Patterson’s lab collects the embryos (tiny white balls of cells) and takes the specimens back to the lab for scientific experimentation.
Experiments focus on identifying the genes that control pigment cell migration. A tiny needle is inserted into zebrafish embryos, delivering a substance that knocks out the function of a specific gene. The team then observes the developmental consequences of knocking out that gene. If it disrupts normal stripe formation, then that gene likely plays a role in regulating the migration of pigment cells.
Zebrafish embryos are selected for use in an experiment.
RIC sophomore Melanie Cragan transfers zebrafish embryos into a strip tube for DNA extraction (photo left). The embryos will then be microinjected with the DNA (photo right).
Curiosity – the impulse to discover how and why things are the way they are – is an impulse shared by humans; however, this trait is amplified in the scientific fields. Never accepting what seems obvious, scientists continue to delve deeper and to ask how a process can be applied elsewhere. The Patterson lab searches for answers to questions like “How do cells organize into patterns? How do cells know where to go? How do cells know when to stop migrating? Or the greatest mystery of all: How does a single cell become a multicellular organism with thousands of different cell types?” It is this kind of questioning that has led scientists like Patterson to unprecedented discoveries.
Sophomore Melanie Cragan described Patterson as “a wonderful professor and PI.” “Dr. Patterson is exceptional at working with students at every stage of their biology careers,” she said. “I started doing research with her having only taken an intro-level biology class. She has worked with me individually, and very patiently, to help me understand the complexity of her work. It’s a great lab for molecular research.”
RIC’s Department of Biology offers numerous opportunities for laboratory research, led by experts in their field like Patterson. Students benefit from experiential learning, they gain advanced-level lab skills that give them an edge when applying to grad school or med school and they gain invaluable communication skills in writing and presenting their research findings at science conferences.
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