CBE/ENGR 225 Seminar Presents: Todd Oakley, Ph.D., Professor in Dept. of Ecology, Evolution, and Marine Biology, UCSB

Tuesday, January 30, 2017 @4pm, in ESB #2001

Todd Oakley, Ph.D.

Professor, Department of Ecology, Evolution, and Marine Biology

University of California, Santa Barbara


Tuesday, January 31, 2017

4:00 pm

ESB, Room #2001


*Cookies and Coffee will be provided*

Taking the Fork in the Road: The Origin and Diversification of Bioluminescence,

Mating Signals, and Luciferase Proteins in Sea Fireflies

Abstract: For evolutionary biologists, the genetic basis of functional and behavioral diversification is not well

understood because connecting genes to function is difficult in one species, let alone across many species.

For this reason, we study the evolution of bioluminescence, a tractable system for learning the genetic

basis of function across species. We focus on a group of luminous crustaceans, called ostracods. Some

ostracods that we call 'sea fireflies' produce light to startle predators. A subset of these species also use

light as a courtship display, where males spit up glowing mucus to create coded signals that hover in the

water in the dark of night. Over 85 species evolved rather recently in the Caribbean, and each species

employs a distinct courtship signal, each using a luciferase enzyme to catalyze the light reaction. We

discovered genes closely related to sea firefly luciferase, which indicate the evolutionary origin of the

protein. Sea firefly luciferase is a novel gene that originated by duplicating a gene that itself arose by fusing

distant members of a family of ancient domains that expanded in ostracods. We also are discovering that

inherent properties of the enzymatic reaction, including kinetic parameters and the color of light produced,

vary across species. We find that some of these biochemical properties are correlated, and thus probably

have constrained how evolution proceeded. We are making progress toward identifying specific amino acid

changes that cause differences in the enzymatic reactions. In general, we find that when evolution takes a

fork in the road, the result is more diversity. In sea fireflies, the forks in the road involved gene duplication

and speciation. Practically speaking, sea firefly luciferase is used as a marker of biological activities. By

characterizing a diversity of luciferases, and understanding how differences in luciferase sequences modify

biochemical properties, we would be able to engineer a vast array of luciferases that differ in color and