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The Monarch Project 

Monarch Cover


Goal: To develop the migratory monarch butterfly as a model for elucidating the cellular and molecular basis of time-compensated sun compass orientation.


  1. Reconstruct the monarch circadian clock in vitro with cloned clock genes.
  2. Define the circadian clock circuitry in vivo.
  3. Delineate light input pathways.
  4. Determine the molecular and cellular basis of clock-compass interactions.
  5. Use genetic approaches to mark and delete clock neurons.
  6. Clarify the role of the circadian clock in the photoperiodically-induced migratory state.
  7. Establish an Expressed Sequence Tag database.
  8. Initiate transcriptional profiling of nonmigratory and migratory butterflies.
  9. Model a four-dimensional clock.
  10. Sequence and annotate the monarch butterfly genome.



Merlin C, Gegear RJ, Reppert SM (2009).  Antennal Circadian Clocks Coordinate Sun Compass Orientation in Migratory Monarch Butterflies.  Science 325:  1700-1704.

Zhu H, Gegear RJ, Casselman A, Kanginakudru S, Reppert SM (2009).  Defining behavioral and molecular differences between summer and migratory monarch butterflies. BMC Biol 7:14.

Gegear RJ, Casselman A, Waddell S, Reppert SM. (2008).    Cryptochrome mediates light-dependent magnetosensitivity in Drosophila.  Nature 454: 1014-1018.

Zhu H, Sauman I, Yuan Q, Casselman A, Emery-Le M, Emery P, Reppert SM (2008). Cryptochromes define a novel circadian clock mechanism in monarch butterflies that may underlie sun compass navigation. PLoS Biol. 6:e4.

Zhu H, Casselman A, Reppert SM (2008). Chasing migration genes: A brain expressed sequence tag resource for summer and migratory butterflies (Danaus plexippus). PLoS ONE 3:e1345.

Reppert SM (2007).   The ancestral circadian clock of moarch butterflies:  Role in time-compensated sun compass orientation.  Cold Spring Harb. Symp. Quant. Biol.  72:113-118.

Song S-H, Ozturk N, Denaro TR, Arat NO, Kao Y-T, Zhu H, Zhong D, Reppert SM, Sancar A (2007). Formation and function of flavin anion radical in cryptochrome 1 blue-light photoreceptor of monarch butterfly. J. Biol. Chem. 282:17608-17612.

Yuan Q, Metterville D, Briscoe AD, Reppert SM (2007). Insect cryptochromes: Gene duplication and loss define diverse ways to construct insect circadian clocks. Mol. Biol. Evol.  24:948-955.

Reppert, S.M. (2006). A colorful model of the circadian clock. Cell 124:233-236.  

Zhu H, Yuan Q, Briscoe AD, Froy O, Casselman A, Reppert SM (2005). The two CRYs of the butterfly. Curr. Biol. 15:R953-R954.  

Sauman, I., Briscoe, A.D., Zhu, H., Shi, D., Froy, O., Stalleichen, J., Yuan, Q., Casselman, A., Reppert, S.M. (2005). Connecting the navigational clock to sun compass input in monarch butterfly brain. Neuron 46:457-467. 

Reppert, S.M., Zhu, H., White, R. (2004). Polarized light help monarch butterflies navigate. Curr. Biol. 14: 155-158.  

Froy O, Gotter AL, Casselman AL, Reppert SM. (2003). Illuminating the circadian clock in monarch butterfly migration. Science 300:1303-1305.