Section: Figures

Postdoctoral Position Available

Steven Reppert, M.D.

Academic Role: Professor

Faculty Appointment(s) In:
   Neurobiology

Other Affiliation(s):
   Interdisciplinary Graduate Program
   Program in Neuroscience

Figure 1.  Proposed monarch butterfly circadian clock mechanism.  The main gear of the clock mechanism is an autoregulatory transcription feedback loop in which CLK and CYC heterodimers drive the transcription of the per, tim, and cry2 genes through E box enhancer elements; in addition to per, there are CACGTG E box elements within the 1.5 kb 5’ flanking regions of the butterfly tim and cry2 genes (data not shown).  TIM (T), PER (P), and CRY2 (C2) form complexes in the cytoplasm and CRY2 is shuttled into the nucleus where it shuts down CLK:CYC-mediated transcription.  PER is progressively phosphorylated and likely helps translocate CRY2 into nucleus.  CRY1 (C1) is a circadian photoreceptor which, upon light exposure (lightning bolt) causes TIM degradation to gain access to the central clock mechanism.  The thick gray arrows represent output functions for CRY1 and for CRY2.

Figure 2. Brain clocks and circuits. Schematic representation of neurons and fibers expressing different circadian clock proteins in monarch butterfly brain. Regions expressing TIM, PER, CRY1 and/or CRY2 are highlighted in red. In these areas the four clock proteins partially colocalize. Areas expressing TIM or CRY1 are indicated in pink. In these regions the two clock proteins do not colocalize. CRY1 positive fibers are represented by continuous orange lines. Projections of dorsal rim area photoreceptors are indicated by dotted orange lines. Neurons and fibers expressing exclusively CRY2 are represented in blue and within the central body are shown as blue circles and blue hatching. Areas positive exclusively to TIM and PER are indicated in light blue and green, respectively. PL, pars lateralis; PI, pars intercerebralis; SOG, subesophageal ganglion; CB, central body; LO, lobula; ME, medulla; LA, lamina; RE, retina (Kyriacou CP, J Biol 2009, 8:55).

Figure 3. Clock-sun compass interactions.

Office: LRB 728 A-D Rm 728
Phone: 508-856-6148
E-mail: Steven.Reppert@umassmed.edu

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Postdoctoral Position Available A postdoctoral position is available to study in this laboratory. Contact Dr. Reppert for additional details.