In one of the most scientifically intriguing migrations known to man, the Monarch butterfly each year flies from as far as the northeast and Canada to just a few mountainous acres in Michoacan, Mexico. The roundtrip journey, evidence of which winged its way through the Brazos Valley just a few weeks ago, is like clockwork — an epic trip governed by the insects’ circadian clock and the Sun’s daily movement across the sky. And yet, basic questions about the phenomenon remain.
Unraveling the mysteries of the migration and the role of internal clocks in the process is a focus of newly hired Texas A&M University biologist Christine Merlin.
“It’s incredible how such a fragile insect can complete a long-range migration so demanding,” said Merlin, who began this fall as an assistant professor in the Department of Biology and is a member of the Center for Biological Clocks Research. “Every piece of it fascinates me, from how it occurs to why they go precisely where they go.”
While she was a postdoctoral researcher at the University of Massachusetts Medical School in the laboratory of Prof. Steven Reppert, Merlin and colleagues showed that the clocks necessary for flight orientation lie in the creatures’ antennae — a departure from the previous conventional wisdom that the brain controlled the mechanism, given that it controls behavioral rhythmicity in virtually every other animal, including humans.
The conclusion stemmed from Merlin’s and her co-workers’ collective curiosity concerning a decades-old anecdote. Around 50 years ago, entomologist Fred Urquhart found that Monarchs became disoriented after he clipped off their antennae. Since then, it had remained just a suspicion until the Massachusetts team confirmed it with more rigorous research.
The team’s experiment exploited technology in a way Urquhart, who merely observed the Monarchs in flight, could not at the time. They used a plastic barrel-like device called a Mouritsen-Frost flight simulator in which a butterfly is connected by tungsten wire to an output system that indicates which direction it is flying. The results were clear: The antennae-less Monarchs flew in every which direction, while those with intact antennae flew southwesterly, the migratory direction.
“What I’m interested in looking at now is the role of the circadian clock in the induction of the migration,” Merlin said. “Migration begins every year in the fall, when the day lengths change. The shortened day lengths might be a cue for the Monarchs to start their migration. And if we can show this is the case and that the circadian clock is involved, we can now start to understand the genetic program that is allowing the migratory behavior.”
The research is easier because University of Massachusetts scientists during Merlin’s postdoctoral time there sequenced the Monarch genome, while Merlin herself started developing genetic tools allowing her to study and disrupt the butterfly’s genes in vivo in a similar fashion to the methods used by researchers to knock out genes in genetic models, such as mice. Merlin hopes that the genetic approaches she’s developing will lead to understanding the genetic basis of the Monarch migration.
Merlin earned her bachelor’s, master’s and doctoral degrees studying animal biology, invertebrate physiology and insect physiology, respectively, at the University Paris 6 Pierre and Marie Curie in France. She began her postdoctoral fellowship at the University of Massachusetts in 2007.
One advantage of working in Texas is that it puts Merlin squarely in the path of the migration both ways — the Monarchs flutter through Texas again in the spring on their way back up north. Another reason she chose Texas A&M, Merlin said, is because of the strength of Texas A&M Biology’s circadian program within its Center for Biological Clocks Research. The interdisciplinary center coordinates research among circadian rhythms scientists not only in the department but also across the university, bringing together faculty from several units, including the colleges of Science, Agriculture and Life Sciences, and Veterinary Medicine & Biomedical Sciences as well as the Texas A&M Health Science Center.
Merlin is the most recent in a pair of hires for the center, which also features her husband, Jerome Menet, an assistant professor who most recently completed postdoctoral research at Brandeis University and studies circadian transcription in mice. Menet’s laboratory investigates the molecular mechanisms that allow circadian clocks and clock genes to regulate gene expression in mice.
Find more information about Merlin’s research.
To learn more about the Texas A&M Center for Biological Clocks Research, visit http://clocks.tamu.edu/.
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Contact: Vimal Patel, (979) 845-7246 or firstname.lastname@example.org or Christine Merlin, (979) 862-2457 or email@example.com