[Frontiers in Bioscience E2, 1394-1404, June 1, 2010]

Biological clocks and rhythms in intertidal crustaceans

Horacio O. de la Iglesia, Yun-Wei A. Hsu

1Department of Biology and Friday Harbor Laboratories, University of Washington, Box 351800, Seattle, Washington 98195-1800

1Departamento de Bioquimica y Biologia Molecular del Instituto Nacional de Perinatologia, Isidro Espinosa de los Reyes, Mexico, 2Departamento de Investigacion en Tabaquismo y EPOC, Instituto Nacional de Enfermedades Respiratorias (INER) "Ismael Cosio Villegas", Mexico

TABLE OF CONTENTS

1. Abstract
2. The temporal environment of the intertidal zone
3. Biological timing systems in intertidal animals
4. Entrainment of circatidal rhythms
5. Neural substrates of circatidal rhythms
6. Chemical signals underlying circatidal rhythmicity
6.1. Pigment-dispersing hormone (PDH)
6.2. Red pigment-concentrating hormone (RPCH)
6.3. Crustacean hyperglycemic hormone (CHH)
6.4. Serotonin
6.5. Melatonin
7. The circatidal clockwork
8. Acknowledgments
9. References

1. ABSTRACT

Animals with habitats within the intertidal zone are exposed to environmental cycles that include the ebb and flow of tidal waters, changes in tidal levels associated with the lunar month, the light-dark cycle and the alternation of seasons. This intricate temporal environment results in the selection of biological timing systems with endogenous clocks that can oscillate with this wide range of periodicities. Whereas great progress has been made in our understanding of the molecular and neural bases of circadian rhythms, that is, endogenous rhythms synchronized to the solar day, there is little understanding on how circatidal rhythms, namely endogenous rhythms synchronized to tides, are generated. Intertidal crustaceans have been a pivotal group for the demonstration of the endogenous nature of circatidal rhythms and their mechanisms of entrainment. We review here some of the classic work using intertidal crustaceans to unmask basic properties of circatidal systems, as well as work from our laboratory that aims to identify putative chemical signals that could be involved in the circatidal systems of decapod crustaceans.