Research: CIRCADIAN (daily) CONTROL represents a very fundamental yet still very poorly understood feature of higher organisms. Jet lag is a symptom of the disruption of our circadian system. Most organisms--as well as individual eukaryotic cells and some bacteria--possess a temporal control mechanism over many biochemical and physiological processes. Our research is concerned with the basic molecular and cellular mechanisms responsible for these rhythms in the bioluminescent dinoflagellate Gonyaulax polyedra. Earlier studies included the first demonstration of the phase-dependency of shifting of the clock by light and its action spectrum, as well as the unique ability of inhibitors of protein synthesis to cause phase-shifts. Inhibitors of protein phosphatases and kinases, on the other hand, cause period changes, as do many mutants in species examined. In Gonyaulax the circadian rhythm of bioluminescence involves a daily synthesis and destruction of two proteins involved in the biochemical reaction. While the amounts of these proteins increase and decrease by a factor of 10 on a daily basis, the mRNAs for these proteins remain at the same level day and night. Synthesis is thus controlled at the translational level, a feature so far unique to this system. Current studies are concerned with the identification of proteins binding to message that are responsible for this unique mechanism for the circadian regulation of gene expression.
Selected Publications: Nealson, K. H. and Hastings, J. W. (2006) Quorum sensing on a global scale: massive numbers of bioluminescent bacteria make milky seas. Appl. Environ. Microbiol. 72:2295-2297 Liu, L. and Hastings, J. W. (2006) Novel and rapidly diverging intergenic sequences between tandem repeats of the luciferase genes in seven dinoflagellate species. J. Phycology 42:96-103 Schultz, W., Liu, L., Cegielski, M., and Hastings, J. W. (2005) Crystal structure of a pH-regulated luciferase catalyzing the bioluminescent oxidation of open tetrapyrrole. Proc. Natl. Acad. Sci. USA 102:1378-1383 Liu, L., Wilson, T. and Hastings, J. W. (2004) Molecular evolution of dinoflagellate luciferases, enzymes with three catalytic domains in a single polypeptide. Proc. Natl. Acad. Sci. USA 101:16555-16560 Okamoto, O. K. and Hastings, J. W. (2003) Novel dinoflagellate circadian-clock genes identified through microarray analysis of a phase shifted clock. J. Phycol., 39: 519-526. Comolli, J., Fagan, T. F. and Hastings, J. W. (2003) A type-1 phosphoprotein phosphatase from a dinoflagellate as a possible component of the circadian mechanism. J. Biol. Rhythms 18:367-376 Rossini, Carlos, Taylor, W.R, Fagan, T.F. and Hastings, J.W. (2003) Lifetimes of mRNAs for clock-regulated proteins in a dinoflagellate. Chronobiology International 20: 963-976 Fagan, T.F. & Hastings, J. W. (2002) Phylogenetic analysis indicates multiple origins of chloroplast glyceraldehyde-3-phosphate dehydrogenase genes in dinoflagellates. Mol. Biol. Evol. 19: 1203-07. Viviani, V. R., Hastings, J. W. and Wilson, T. (2002) Two bioluminescent Diptera: the North American Orfelia fultoni and the Australian Arachnocampa flava. Similar niche, different bioluminescence systems. Photochem. Photobiol. 75: 22-27. Li, Liming, Liu, Liyun, Hong, Robert, Robertson, Deborah and Hastings, J. W. (2001) N-terminal intramolecularly conserved histidines of three domains in Gonylaulax luciferase are responsible for loss of activity in the alkaline region Biochemistry40: 1844-1849. Okamoto, O. K., Liu, Liyun, Robertson, D. L. and Hastings, J. W. (2001) Members of a Dinoflagellate Luciferase Gene Family Differ in Synonymous Substitution Rates. Biochemistry 40: 15862-15868. Hastings, J.W. (2001)Bioluminescence. (N. Sperelakis, ed.), In: Cell Physiology, 3rd Edition, Academic Press, NY., pp 1115-1131. Hastings, J. W. (2000) Bioluminescence, Microbial, in Encyl. Microbiol. vol. 1: 520-529. Academic Press, N.Y. Hastings, J. W. and Greenberg, E. P. (1999) Quorum Sensing: The explanation of a curious phenomenon reveals a common characteristic of bacteria. J . Bacteriol. 181: 2667-2668. Comolli, James and Hastings J. W. (1999) Novel Effects on The Gonyaulax Circadian System Produced by the Protein Kinase Inhibitor Staurosporine. J. Biol. Rhythms 14: 10-18. Fagan, Thomas, Morse, David and Hastings, J. W. (1999) Circadian synthesis of a nuclear-encoded chloroplast glyceraldehyde-3-phosphate dehydrogenase in the dinoflagellate Gonyaulax polyedra is translationally controlled. Biochemistry 38: 7689-7695. Li, L. and Hastings, J.W. (1998) The structure and organization of the Gonyaulax polyedra luciferase gene. Plant Molecular Biology 36: 275-284. Wilson, T. & Hastings, J.W. (1998) BioluminescenceAnnu. Rev. Cell Devel. Biol. 14: 197-230. Hastings, J. W. and Morin, J. G. (1998) Photons for reporting molecular events: Green fluorescent protein and four luciferase systems. pp. 17-41 in Green Fluorescent Protein (Martin Chalfie and Steven Kain, Eds.) Wiley-Liss, N.Y. Li, Liming, Hong, R. and Hastings, J. W. (1997) Three functional luciferase domains in a single polypeptide chain. Proc. Natl. Acad. Sci. 94: 8954-8958.
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