Christine Merlin

In 2021, Merlin was credited as assisting in a research article focused on the magnetoreception of monarch butterflies. While the molecular and cellular mechanisms underlying magnetic sensing has not yet been discovered, the connection to the photoexcitation of CRY proteins has been linked to both CRY1 in Drosophila and CRY2 in monarchs and humans. This discovery in humans and monarchs was identified due to the finding that overexpression in CRY-deficient flies restored magnetosensitivity, suggesting they perform photochemical reactions for the magnetosensitivity in the fly's cellular environment. In order to test reorientation using magnetic inclination in monarchs, both fall migrant monarchs and wild-type laboratory monarchs were placed in a flight simulator that manipulated different magnetic field parameters: declination, inclination, and intensity. It was found that both variants of monarchs did not display hyperactivity to the geomagnetic field, but both variants did display an increase in wingbeats upon reversing magnetic inclination. Creating a behavioral assay from this experiment led to the evaluation that the Drosophila CRY1 (dpCry1) was necessary for monarch light-dependent magnetoreception, while the Drosophila CRY2 (dpCry2) was not. The antennae and compound eyes were tested to see if they were necessary for light-dependent magnetoreception. Blocking either one of these organs with black paint led to impaired responses to ambient magnetic inclination and reversal of ambient magnetic inclination. This indicates that the monarch's antennae and compound eyes are necessary for magnetosensing, and that impairing one of these organs cannot be compensated by the other.

As of 2021, the Merlin lab is currently focused on utilizing reverse genetic tools to further unravel clockwork mechanisms in the monarch, determine how previously identified candidate genes contribute to butterfly migration and photoperiodic sensing, as well as dissect the genetic basis of the magnetic sense. The lab is currently working with known clock genes in vivo to understand circadian repressive mechanisms within the monarch and gain further knowledge regarding how insect clocks have evolved. Merlin is also exploring means to expand the monarch genetic toolbox with a focus on developing a reliable CRISPR/Cas9-mediated knock-in approach to introduce reporter tags into loci of interest within the monarch genome and gain insights into the clock circuitry in the brain.

Merlin and her lab have been consistently interested in exploring methods of selective genetic editing via tools such as zinc finger proteins, which enable the creation of targeted gene knockouts within a specified locus. In 2016, Merlin and colleagues demonstrated that both TALENs and CRISPR/Cas9 technologies could be utilized in a similar manner to create highly efficient, heritable, targeted mutagenesis at selected genomic loci. Merlin and her team were able to generate genetic knockouts of the Cry2 and Clk genes within the monarch genome, two notable clock genes responsible in part for the regulation and modulation of the monarch circadian clock. These knockouts were shown to be heritable, with the injection of less than 100 eggs being sufficient to recover mutant progeny; enabling the generation of mutant knockout lines in around 3 months. These findings provided new research methods for the genetic manipulation and study of monarch clock genes, as is currently being explored by the Merlin Lab.

In 2013, she became an assistant professor of biology at Texas A&M University, where she works now. She joined the Center of Biological Clocks Research as a faculty member studying biology, specifically the circadian clock regulation of monarch butterfly migration. She also became a faculty member of Texas A&M's Genetics and Neuroscience interdisciplinary program in 2014, as well as their Ecology and Evolutionary Biology interdisciplinary program in 2015.

In 2011, Merlin (along with Steven Reppert, Shuai Zhan, and Jeffrey Boore) contributed to outlining the genome of the migratory monarch butterfly and described the operation of circadian clocks as a method of regulating migration. The monarch clock relies on a transcription-translation feedback loop (TTFL) that contains many of the same genetic components as the clocks of other arthropods, such as Drosophila melanogaster. One notable difference between the monarch clock and the Drosophila melanogaster clock is the appearance of both a light-sensitive CRY1 and a transcriptionally repressive CRY2 in the monarch clock, while Drosophila melanogaster only contains CRY1. As most arthropods have both CRY types, this result provided additional evidence that both CRY were at “the base of arthropod evolution.” They highlighted two main uses for the clock. One use is for sun compass orientation, which allows the monarch to navigate towards its destination by detecting the horizontal position of the sun and the polarized skylight patterns produced. The other use is for the initiation of migration by detecting decreasing day length in the autumn.

Merlin has helped publish over 25 papers during the course of her career and has garnered over 2000 citations for her work.

Christine Merlin was born on September 24, 1980 in southwestern France. She attended Pierre and Marie Curie University in Paris, where she received a BS in animal biology, an MS in invertebrate physiology, and finally her PhD in insect physiology in 2006. She studied circadian rhythms in moths in Versailles at the National Institute for Research on Agronomy in the lab of Emmanuelle Jacquin-Joly and Martine Maibeche-Coisne while studying for her doctorate. In 2007, she began working in the lab of Steven Reppert at the University of Massachusetts Medical School. There, she studied the migration of monarch butterflies, established reverse genetics in this new model system, and collaborated on a paper outlining the monarch genome.