Loss of functional cryptochrome 1 reduces robustness of 24-hour behavioral rhythms in monarch butterflies
Samantha E. Iiams,
Guijun Wan,
Jiwei Zhang,
Aldrin B. Lugena,
Ying Zhang,
Ashley N. Hayden,
Christine Merlin
Affiliations
Samantha E. Iiams
Department of Biology and Center for Biological Clocks Research, Texas A&M University, College Station, TX 77843, USA; Genetics Interdisciplinary Program, Texas A&M University, College Station, TX 77843, USA
Guijun Wan
Department of Biology and Center for Biological Clocks Research, Texas A&M University, College Station, TX 77843, USA; Department of Entomology, College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, China
Jiwei Zhang
Department of Biology and Center for Biological Clocks Research, Texas A&M University, College Station, TX 77843, USA
Aldrin B. Lugena
Department of Biology and Center for Biological Clocks Research, Texas A&M University, College Station, TX 77843, USA
Ying Zhang
Department of Biology and Center for Biological Clocks Research, Texas A&M University, College Station, TX 77843, USA
Ashley N. Hayden
Department of Biology and Center for Biological Clocks Research, Texas A&M University, College Station, TX 77843, USA
Christine Merlin
Department of Biology and Center for Biological Clocks Research, Texas A&M University, College Station, TX 77843, USA; Genetics Interdisciplinary Program, Texas A&M University, College Station, TX 77843, USA; Corresponding author
Summary: Light is one of the strongest cues for entrainment of circadian clocks. While some insect species rely only on visual input, others like Drosophila melanogaster use both the visual system and the deep-brain blue-light photoreceptor cryptochrome for entraining circadian rhythms. Here, we used the monarch butterfly Danaus plexippus (dp), which possesses a light-sensitive cryptochrome 1 (dpCry1), to test the conservation of mechanisms of clock entrainment. We showed that loss of functional dpCry1 reduced the amplitude and altered the phase of adult eclosion rhythms, and disrupted brain molecular circadian rhythms. Robust rhythms could be restored by entrainment to temperature cycles, indicating a likely functional core circadian clock in dpCry1 mutants. We also showed that rhythmic flight activity was less robust in dpCry1 mutants, and that visual impairment in dpNinaB1 mutants impacted flight suppression at night. Our data suggest that dpCRY1 is a major photoreceptor for light-entrainment of the monarch circadian clock.
