Laboratory of molecular chronobiology (I. Sauman)

 

Flies expressing GFP in eyesCircadian biological clocks are found in most living organisms and their fundamental properties are highly conserved in vertebrates and invertebrates. The fruitfly, Drosophila melanogaster served as a premier insect species for the molecular analysis of the circadian rhythms. Because of the functional similarities of the circadian clocks among all metazoans, it was suggested that the molecular mechanisms underlying the clock function would be conserved as well. Surprisingly, we have found striking differences between the molecular regulations of the circadian timing system even among holometabolous insects. The long-term goal of our laboratory is to gain a better understanding of the cellular and molecular mechanisms that underlie circadian rhythmicity.

 

Connecting the Navigational Clock to Sun Compass Input in Monarch Butterfly Brain

In their spectacular annual fall migration from North America to the overwintering sites in Mexico, monarch butterflies (Danaus plexippus) use the angle of plane of polarized light together with time compensated sun compass for navigation. In collaboration with the laboratory of Prof. Reppert, we have identified photoreceptors in the monarch eyes specialized for detection of polarized light in the UV spectrum. Furthermore we have discovered and characterized a molecular neural wiring connecting circadian biological clock with the signal pathway of polarized light entering the brain of the migratory butterfly. Due to the constant movement of the sun during the day, information from the circadian clock is critical for maintaining the constant direction of the butterflies’ migration, often exceeding thousands of miles. The monarch butterfly represents the first organism where such unique molecular neural pathway was identified. The results of this research was reported in several international journals including the prestigious American journal The Scientist and Science.

Sauman, I., Briscoe, A., Zhu, H., Shi, D., Froy, O., Stalleicken, J., Yuan, Q., Casselman, A. and Reppert, S.M. (2005). Connecting the navigational clock to sun compass input in monarch butterfly brain. Neuron 46, 457-467. [IF 14.439]

Zhu, H., Sauman, I., Yuan, Q., Casselman, A., Emery-Le, M., Emery, P. and Reppert, S.M. (2008). Cryptochromes define a novel circadian clock mechanism in monarch butterflies that may underlie sun compass navigation. PLoS Biol. 6(1), e4. doi:10.1371/journal.pbio.0060004 [IF 14.109]

Monarch butterflies (Danaus plexipus)

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