John D. Palmer

TIDAL RHYTHMS: THE CLOCK CONTROL OF THE RHYTHMIC PHYSIOLOGY OF MARINE ORGANISMS

1. A great number of vital processes are rhythmic and the rhythms quite often persist in constant conditions. The best‐known rhythms are circadian; much less is known about circalunadian rhythms, and this review was prepared in an attempt to rectify this deficiency. All through the article comparisons are drawn between circalunadian and circacian rhythms.

Persistent, vertical-migration rhythms in benthic microflora.: II. Field and Laboratory Studies On Diatoms From The Banks Of The River Avon

The vertical migration of two Euglena species and several diatom species into and out of the sediment on the banks of the River Avon has been studied under natural conditions. All species have been shown to migrate vertically upwards when exposed during daylight. Tidal flooding of the sediment is generally preceded by re-burrowing of the algae beneath the surface. Methods have been devised to follow these migrations in both the field and laboratory. Laboratory experiments show that these migrations are rhythmic, continuing under constant illumination and temperature and removed from tidal influence. The effect of three different temperatures and three different light intensities has been investigated. Transfer from low to high temperatures has been shown to reset the phase of the rhythm. The results are discussed in relation to other work and to the ‘biological clock’ hypothesis.

PERSISTENT, VERTICAL-MIGRATION RHYTHMS IN BENTHIC MICROFLORA. VI. THE TIDAL AND DIURNAL NATURE OF THE RHYTHM IN THE DIATOM HANTZSCHIA VIRGATA

1. The diatom, Hantzschia virgata, appears on the surface sands of Barnstable Harbor, Mass., during daytime low tides. Surface accumulations of this organism reach such concentrations that the sand takes on a golden-brown color. As the tide returns the cells re-burrow into the sand.2. The cells can be prevented from emerging onto the surface sands at low tide by artificially darkening the area with an opaque covering just as the tide recedes. Cells already on the surface can be made to re-burrow by similarly placing them in darkness.3. The vertical-migration rhythm will persist in the laboratory in constant illumination, constant temperature, and away from the influence of the tide for as long as eleven days. During this time the cells remain in approximate synchrony with the feral cells in nature.4. In nature, when the times of low tide approach sunset, the cells rephase their rhythm to the early morning hours of daylight. Cells collected during late afternoon low tides and returned to L:D or L:L in the ...

The chronomutagenic effect of deuterium oxide on the period and entrainment of a biological rhythm.

The effect of deuterium oxide on the locomotor activity rhythm of the house mouse, Mus musculus, was measured in various environmental conditions.1. In the initial experiments, in which mice were kept in constant low (0.2 foot candle) illumination, D2O concentrations of 5% through 30% (in 5% increments) were administered via the drinking water. Increased concentrations lengthened the period, proportionally, with 30% D2O causing a mean period lengthening of 7.4%.2. Increasing the intensity of illumination in constant conditions can lengthen the period of the mouse locomotor activity rhythm. It was felt that deuterium might be changing the way in which the mice interpreted the light intensity, thus changing the period. Both blind mice, and mice kept in constant darkness were tested at various dosages. The results did not differ significantly from those obtained for mice in constant low illumination, thus showing D2O does not act to alter the period by changing the way in which the mice interpret light inten...

COMPARATIVE STUDIES IN AVIAN PERSISTENT RHYTHMS: SPONTANEOUS CHANGE IN PERIOD LENGTH.

Abstract 1. 1. The persistent activity rhythms of four birds (a Towhee, a Grosbeak and two House Sparrows) were studied for periods up to 4 months. 2. 2. One of the House Sparrows was found to possess a “statistical activity-rhythm” which persisted after the over, circadian rhythm abruptly disappeared. 3. 3. The study emphasizes and compares “spontaneous” changes in the period length of circadian rhythms. Such changes commonly occurred in three of the four birds. 4. 4. The “spontaneous changes” are explained as abrupt alteration in the physiological make-up of the birds, resulting in a sudden change in their sensitivity to the constant conditions in which they were maintained.

Daily variations of marrow and splenic erythropoiesis, pinna epidermal cell mitosis and physical activity in c57bl/6j mice.

Regular daily fluctuations in spontaneous physical activity and in the mitotic indices of marrow and splenic erythroid elements and pinna cells, were observed. Both male and female C57Bl/6J mice showed these rhythms. Of particular interest was the finding that the spleen and the marrow mitotic activity showed a reciprocal relationship. The role of several hormones and the biological clock in control of these rhythms are discussed.

The role of phenylalanine in differentiating amphibian melanocytes.

Abstract To see whether phenylalanine serves as a substrate in melanogenesis, hanging drop explants of neural crest from amphibian (Ambystoma maculatum and A. mexicanum) embryos were subjected on the seventh day in vitro to treatment with phenylalanine-3H and studied by means of light microscopic radioautography. All melanin-containing cells showed label. On the other hand, when puromycin, an inhibitor of protein synthesis, together with the labeled amino acid was administered to the cultures, no radioactivity was incorporated by pigmented cells. Comparable results were obtained when leucine was substituted for phenylalanine. In control experiments, puromycin and labeled tyrosine or 3,4-dihydroxyphenylalanine (DOPA), both known precursors for melanin synthesis, were administered to the neural crest cultures. In these experiments, puromycin had no effect on the incorporation of label by pigmented cells. Our data strongly indicate that in differentiating amphibian melanocytes with functional pigment-forming systems, phenylalanine is used in protein synthesis, but does not serve as a substrate for the tyrosine-tyrosinase system. In another series of experiments, explants of neuroepithelium (neural crest anlage) were grown from the time of explantation to the seventh day in vitro in the presence of phenyllactic acid, an analog of phenylalanine. Pigment cells developed normally. These results suggest that phenylalanine plays little or no role in pigment cell differentiation.

The effect of actinomycin-D on regeneration time inTubularia

SummaryActinomycin-D was administered to regenerating stem segments ofTubularia spectabilis to ascertain if the synthesis of RNA is necessary for the completion of hydranth development. Preliminary experiments have indicated that this drug suppresses a burst of H3-uridine uptake into the extractable RNA of these regenerates.Wound healing was unaffected by doses of this drug which significantly retarded subsequent hydranth differentiation.The degree of regenerative suppression in this animal increases as a direct function of the administered concentration of actinomycin-D.The period of greatest sensitivity to actinomycin-D occurs early in the regenerative period: hours 6–17 following hydranth amputation. Wittman (1969) has demonstrated a puromyein-sensitive peak of C14-leucine uptake into proteins synthesized at hour 25 or beyond. The authors conclude that the control of hydranth differentiation in regeneratingTubularia resides at the transcriptional level of gene action.ZusammenfassungActinomycin-D wurde den sich neubildenden Stammsegmenten derTubularia spectabilis zugefügt um festzustellen, ob die Synthese von RNS für die Vollendung der Hydranthentwicklung notwendig ist. Vorläufige Experimente haben gezeigt, daß diese Droge eine Steigerung von H3-Uridineverbindung in das extrahierbare RNS dieser sich neubildenden Tiere unterdrückt.Das Heilen von Wunden wurde nicht beeinflußt durch Dosen dieser Droge, die späteres Hydranthdifferenzieren bedeutsam aufhielten.Der Grad der Neubildungsunterdrückung in diesem Tier steigt als direkte Funktion der zugefügten Konzentration von Actinomyein-D.Die Zeit der größten Empfindlichkeit für Actinomycin-D fällt in den Anfang der Neubildungsperiode: zwischen die 6. und 17. Std nach der Hydranthamputation. Wittman (1969) zeigte einen Puromycin-empfindlichen Höhepunkt von C14-Leucineverbindung in Proteine, die in der 25. Std oder später synthetisiert wurden. Die Verfasser ziehen den Schluß, daß die Kontrolle des Hydranthdifferenzierens in sich neubildendenTubularia auf der transkriptionalen Stufe der Genenwirkung liegt.

INTRODUCTION TO BIOLOGICAL RHYTHMS AND CLOCKS

Many biological processes, at the multicellular and cellular levels of organization, undergo regularly recurring quantitative and qualitative changes. Highs in these processes are repeated with such beat-like regularity that the processes are referred to as being rhythmic. A biological clock would be expected to be built of biochemical components, and all usual chemical reactions are known to be sensitive to changes in temperature. Another property of biological clocks is their insensitivity to a great variety of chemical inhibitors, including narcotizing agents and sub-lethal doses of metabolic poisons. Another major property of biological rhythms is one that might not be anticipated: they are innate. That is, the period is not learned, or imprinted upon organisms by the 24-hour day-night light and temperature cycles produced by the rotation of the earth. This has been demonstrated by raising animals from birth—and seeds from the time of germination-in static laboratory conditions. The developing organisms either become rhythmic de novo , or they are arrhythmic but can be made to become rhythmic by subjecting them to a single, non-periodic stimulus.