Functional Conservation of Clock Output Signaling between Flies and Intertidal Crabs

BECKWITH, EJ; LELITO, KR; HSU, YW; MEDINA, BM; SHAFER, OT; CERIANI, MF; DE LA IGLESIA, HO

JOURNAL OF BIOLOGICAL RHYTHMS.

SAGE PUBLICATIONS INC

Lugar: Thousand Oaks, California.; Año: 2011 vol. 26 p. 518 - 529

0748-7304

Intertidal species have both circadian and circatidal clocks. Although the behavioral evidence for these oscillators is more than 5-decades old, virtually nothing is known about their molecular clockwork. PIGMENT-DISPERSING HORMONES (PDHs) were originally described in crustaceans. Their insect homologs, PIGMENT-DISPERSING FACTORS (PDFs), have a prominent role as clock output and synchronizing signals released from clock neurons. We show that gene duplication in crabs has led to two PDH genes (ƒÒ-pdh-I and ƒÒ-pdh-II). Phylogenetically, ƒÒ-pdh-I is more closely related to insect pdf than to ƒÒ-pdh-II and we hypothesized that ƒÒ-PDH-I may represent a canonical clock output signal. Accordingly, ƒÒ-PDH-I expression in the brain of the intertidal crab Cancer productus is similar to that of PDF in Drosophila melanogaster, and neurons that express PDH-I also show CYCLE-like immunoreactivity. Using D. melanogaster pdf-null mutants (pdf01) as a heterologous system, we show that ƒÒ-pdh-I is indistinguishable from pdf in its ability to rescue the mutant arrhythmic phenotype, butƒnƒÒ-pdh-II fails to restore the wildtype phenotype. Application of the three peptides to explanted brains shows that PDF and ƒÒ-PDH-I are equally effective in inducing the signal transduction cascade of the PDF receptor (SLNV) but ƒÒ-PDH-II fails to induce a normal cascade. Our results represent the first functional characterization of a putative molecular clock output in an intertidal species and may provide a critical step towards the characterization of molecular components of biological clocks in intertidal organisms.