The long-term objectives of this project are to identify the circadian clock and understand its mechanism at the cellular level. The circadian (circa, about; ides, one day) biological clock is a physiological mechanism responsible for the timing, on a daily basis, of many fundamental processes, such as gene expression and cell division. In higher organisms, it also regulates blood hormone levels, for example, and more complex phenomena such as activity and alertness. Its importance in human physiology rests on its involvement in the timing of such processes, which can be disrupted environmentally, as in jet lag or shift-work scheduling. Endogenous malfunctions are also hypothesized, and have been associated with the pathology of certain depressions. The biological structure of the circadian clock is not known. We strongly believe that studies of well-chosen unicellular organisms, which can be easily and relatively inexpensively automated to provide statistically meaningful data, may be used to gain basic knowledge of general validity. Clocks in simple organisms share many of the properties of human clocks, and fundamental knowledge from any organism is commonly found to be applicable to others.
The specific aims of this proposal are to elucidate in Gonyaulax polyedra how the effects of (1) light (particularly in relation to color) nd (2) biomolecules affecting circadian rhythms (particularly endogenous substances), are transduced to and interact with the cellular clock mechanism. In the later study, we hope to be able to isolate, identify and locate cellular components of the clock mechanism itself. In order to carry out these projects we plan to develop new and versatile instrumentation allowing for the control of experimental conditions, along with data acquisition and analysis on a long term basis. Action spectra will be determined in several protocols for different kinds of photoresponses of the circadian system: period length, phase shifting by light pulses, self selection of cell position in a light gradient and self selection for phasing in light cycles of different colors. Both narrow band filters and the large spectrograph (Okazaki, Japan) will be used. Creature and gonyauline (a newly) discovered molecule isolated from Gonyaulax) will be studied in relation to their ability to speed up the circadian clock, in view of determining its mechanism. The kinetics of uptake of these molecules will be determined, along with their metabolic fates and associated enzymes. Radiolabeled creatine and gonyauline will be used as probes to identify cellular sites and molecular components of the clock, based on binding studies. We will also screen for other substance found in the cells and medium which may play a role in cell communication, circadian period, and patterns of cellular aggregation and motility.

Agency
National Institute of Health (NIH)
Institute
National Institute of Mental Health (NIMH)
Type
Method to Extend Research in Time (MERIT) Award (R37)
Project #
5R37MH046660-02
Application #
3486985
Study Section
Psychobiology and Behavior Review Committee (PYB)
Project Start
1990-07-01
Project End
1995-06-30
Budget Start
1991-08-01
Budget End
1992-06-30
Support Year
2
Fiscal Year
1991
Total Cost
Indirect Cost
Name
Harvard University
Department
Type
Schools of Arts and Sciences
DUNS #
071723621
City
Cambridge
State
MA
Country
United States
Zip Code
02138
Comolli, James C; Fagan, Thomas; Hastings, J Woodland (2003) A type-1 phosphoprotein phosphatase from a dinoflagellate as a possible component of the circadian mechanism. J Biol Rhythms 18:367-76
Fagan, Thomas F; Woodland Hastings, J (2002) Phylogenetic analysis indicates multiple origins of chloroplast glyceraldehyde-3-phosphate dehydrogenase genes in dinoflagellates. Mol Biol Evol 19:1203-7
Comolli, J C; Hastings, J W (1999) Novel effects on the Gonyaulax circadian system produced by the protein kinase inhibitor staurosporine. J Biol Rhythms 14:11-9
Okamoto, O K; Shao, L; Hastings, J W et al. (1999) Acute and chronic effects of toxic metals on viability, encystment and bioluminescence in the dinoflagellate Gonyaulax polyedra. Comp Biochem Physiol C Pharmacol Toxicol Endocrinol 123:75-83
Comolli, J; Taylor, W; Rehman, J et al. (1996) Inhibitors of serine/threonine phosphoprotein phosphatases alter circadian properties in Gonyaulax polyedra. Plant Physiol 111:285-91
Comolli, J; Taylor, W; Hastings, J W (1994) An inhibitor of protein phosphorylation stops the circadian oscillator and blocks light-induced phase shifting in Gonyaulax polyedra. J Biol Rhythms 9:13-26
Roenneberg, T; Taylor, W (1994) Light-induced phase responses in Gonyaulax are drastically altered by creatine. J Biol Rhythms 9:1-12
Morse, D; Hastings, J W; Roenneberg, T (1994) Different phase responses of the two circadian oscillators in Gonyaulax. J Biol Rhythms 9:263-74
Kondo, T; Strayer, C A; Kulkarni, R D et al. (1993) Circadian rhythms in prokaryotes: luciferase as a reporter of circadian gene expression in cyanobacteria. Proc Natl Acad Sci U S A 90:5672-6
Roenneberg, T; Hastings, J W (1991) Are the effects of light on phase and period of the Gonyaulax clock mediated by different pathways? Photochem Photobiol 53:525-33