Functional conservation of clock output signaling between flies and intertidal crabs.
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 (β-pdh-I and β-pdh-II). Phylogenetically, β-pdh-I is more closely related to insect pdf than to β-pdh-II, and we hypothesized that β-PDH-I may represent a canonical clock output signal. Accordingly, β-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 (pdf(01)) as a heterologous system, we show that β-pdh-I is indistinguishable from pdf in its ability to rescue the mutant arrhythmic phenotype, but β-pdh-II fails to restore the wild-type phenotype. Application of the three peptides to explanted brains shows that PDF and β-PDH-I are equally effective in inducing the signal transduction cascade of the PDF receptor, but β-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.
Laboratorio de Genética del Comportamiento, Fundación Instituto Leloir, IIB-BA CONICET, Buenos Aires, Argentina.
Esteban J
EJ
Beckwith
Katherine R
KR
Lelito
Yun-Wei A
YW
Hsu
Billie M
BM
Medina
Orie
O
Shafer
M Fernanda
MF
Ceriani
Horacio O
HO
de la Iglesia
D000595:Amino Acid Sequence; D000818:Animals; D001522:Behavior, Animal / Q000502:physiology; D001683:Biological Clocks / Q000502:physiology*; D003386:Brachyura / Q000033:anatomy & histology / Q000502:physiology*; D001921:Brain / Q000033:anatomy & histology / Q000378:metabolism; D002940:Circadian Rhythm / Q000502:physiology; D029721:Drosophila Proteins / Q000145:classification / Q000235:genetics / Q000378:metabolism*; D004331:Drosophila melanogaster / Q000033:anatomy & histology / Q000502:physiology*; D020440:Gene Duplication; D008969:Molecular Sequence Data; D009474:Neurons / Q000378:metabolism; D009479:Neuropeptides / Q000145:classification / Q000235:genetics / Q000378:metabolism*; D010455:Peptides / Q000145:classification / Q000235:genetics / Q000378:metabolism*; D010641:Phenotype; D010802:Phylogeny; D016415:Sequence Alignment; D015398:Signal Transduction / Q000502:physiology*
D029721:Drosophila Proteins; D009479:Neuropeptides; D010455:Peptides; C113883:pdf protein, Drosophila; C027714:melanophore-dispersing hormone