Output signaling in the circadian clock, evolutionary and functional conservation between flies ands crabs

ESTEBAN J. BECKWITH ; YUN-WEI A. HSU; BILLIE MEDINA; HORACIO O. DE LA IGLESIA; M. FERNANDA CERIANI1

Huerta Grande

Congreso; Second Joint Meeting of the Argentine Society for Neuroscience; 2010

Sociedad Argentina de Neurociencias y el Taller Argentino de Neurociencias

Species that live in the intertidal zone are exposed to the 24-h light-dark cycle and to cyclic ebb and flow oftidal waters. Accordingly, both circadian clocks and biological clocks that oscillate in synchrony with tide,namely circatidal clocks, have been described in several intertidal organisms. Whether these two biologicaltiming systems share common mechanisms remains unknown.We have previously identified two members of the pigment-dispersing hormone family in C. productus,β-PDH-I and β-PDH II. The distribution of β-pdh I-expressing cells in the crab’s brain is similar to that of PDFin Drosophila. Furthermore, β-PDH I shares closer sequence homology with PDF than β-PDH II does, and itis expressed in neurons that also show CYCLE-like staining in the crab’s brain. These results suggest thatβ-PDH I may represent a functional homolog of PDF, which is a critical signal to drive circadian outputs andto couple the circadian network.To further investigate this possibility we transformed Drosophila pdf01 flies by overexpressing either β-PDHI or β-PDH II. Whereas the circadian phenotype of -pdh I-expressing flies was undistinguishable from wildtype flies, -pdh II could only accomplish a modest rescue of the phenotypes associated with the loss of PDFfunction.