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In vitro bioluminescence components of the dinoflagellates Gonyaulax polyedra, G. tamarensis, Dissodinium lunual, and Pyrocystis noctiluca were studied. The luciferases and luciferins of the four species cross-react in all combinations. All of these species possess high-molecular weight luciferases (200,000-400,000 daltons) with similar pH activity profiles. The active single chains of luciferases from the Gonyaulax species have a MW of 130,000 while those from P. noctiluca and D. lunula have a MW of 60,000. Extractable luciferase activity varies with time of day in the two Gonyaulax species, but not in the other two. A luciferin binding protein (LBP) can easily be extracted from the two Gonyaulax species (MW approximately 120,000 daltons), but none could be detected in extracts of either D. lunula or P. noctiluca. Scintillons are extractable from all four species, but they vary in density and the degree to which activity can be increased by added luciferin. Although the biochemistry of bioluminescence in these dinoflagellates is generally similar, the observations that D. lunula and P. noctiluca apparently lack LBP and have luciferases with low MW single chains require further clarification.

Squirrel monkeys (Saimiri sciureus) demonstrate prominent circadian (approx 24 h) rhythms in many behavioral and physiological variables including drinking and body temperature. Both of these rhythms can be entrained by a 24-h light-dark cycle (LD 12:12) but will free-run with an endogenous period in a constantly illuminated (LL:600 lx) environment free of time cues. After radio-frequency lesions were placed stereotaxically in the suprachiasmatic nuclei (SCN) of five monkeys, the circadian rhythm of drinking behavior was disrupted when the monkeys were maintained in LL. However, the circadian rhythm in core body temperature in these animals persisted in LL with a significant circadian spectral component following destruction of the SCN. The SCN thus appear to be of fundamental importance for regulating the circadian organization of drinking; however, an oscillator located elsewhere in the squirrel monkey is capable of generating the core body temperature rhythm.

Various temporal signals in the environment were tested to determine if they could synchronize the circadian timing system of the squirrel monkey (Saimiri sciureus). The influence of cycles of light and dark, eating and fasting, water availability and deprivation, warm and cool temperature, sound and quiet, and social interaction and isolation was examined on the drinking and activity rhythms of unrestrained monkeys. In the absence of other time cues, 24-h cycles of each of these potential synchronizers were applied for up to 3 wk, and the periods of the monkey's circadian rhythms were examined. Only light-dark cycles and cycles of food availability were shown to be entraining agents, since they were effective in determining the period and phase of rhythmic variables. In the presence of each of the other environmental cycles, the monkey's circadian rhythms exhibited free-running periods which were significantly different from 24 h with all possible phase relationships between the rhythms and the environmental cycles being examined.