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V D Gooch

Publications and source records attributed to V D Gooch.

10 recordsLinked to original sources
PubMed2001

Rhythms of differentiation and diacylglycerol in Neurospora.

Although the fungus Neurospora crassa is a relatively simple lower eukaryote, its circadian system may be more complex than previously thought. In this paper we review evidence suggesting that there may be several output pathways coupled in complex ways to a single oscillator, or that there may be more than one oscillator driving independent output pathways. We have described two new rhythms in Neurospora that are not tightly coupled to the rhythm of conidiation bands that is the standard assay for the state of the Neurospora circadian clock. The first is a rhythm in the timing of differentiation, i.e. the production of aerial hyphae and spores. Large regions of the mycelium differentiate synchronously, as if responding to a spatially widespread signal. This rhythm may be distinct from the timer that sets the determination switch controlling the spatial pattern of conidiation bands. The second new rhythm is an oscillation in the levels of the neutral lipid diacylglycerol (DAG). This rhythm is found in all regions of a colony and is not always in phase with the rhythm of conidiation bands. The DAG rhythm shares some characteristics with the differentiation rhythm and has the potential to act as the signal that induces rhythmic differentiation.

Cell Differentiation↗
PubMed1994

Temperature effects on the resetting of the phase of the Neurospora circadian rhythm.

Various temperatures relative to a 25 degrees C control have been applied as phase-resetting agents in release-assay experiments using the conidiation rhythm of the mold Neurospora crassa. The larger the difference in temperature from the 25 degrees C control, the stronger the phase-resetting effects. Phase-resetting curves of the weak type (type 1) are observed for temperatures up to 28 degrees C and down to 22 degrees C, whereas temperatures above 28 degrees C and less than 22 degrees C generally cause phase-resetting curves of the strong type (type 0). Singularity behavior occurs at approximately 22 degrees C and 28 degrees C when 25 degrees C is used as the control temperature. When a different control of 29.5 degrees C is used in a release-assay experiment and the resetting temperature is 25 degrees C, near-singularity behavior is observed.

Circadian Rhythm↗
PubMed1986

Acquisition of circadian bioluminescence data in Gonyaulax and an effect of the measurement procedure on the period of the rhythm.

During measurements of the circadian (approximately 24-hr) rhythms of spontaneous bioluminescence in the marine dinoflagellate Gonyaulax polyedra, the individual cultures in vials were shielded from otherwise constant dim light for 1-3 min every 20-60 min by a photomultiplier housing that was moved from vial to vial. The high-frequency dark pulses caused a small but consistent shortening of the free-running circadian period, but there was no indication that the dark pulses caused entrainment. Hardware and software components of the microcomputer-controlled data collection system are described. A microcomputer controlled the movement of the photomultiplier and acquired the data via an analog-to-digital converter. The algorithms distinguished and separately recorded background glow, intermittent flashes, and total light from populations ranging in number from 10(3) to 10(5) cells in volumes from 1 to 10 ml. Fast video display techniques allowed continuous on-line viewing of incoming data, together with a display of the data recorded over the preceding day or two. Detection of mechanical and software errors coupled with recovery systems maintained high reliability of data collection.

Animals↗
PubMed1981

Precision of the Gonyaulax circadian clock.

Under constant conditions, the circadian bioluminescent glow rhythm in populations (10(5) cells) of Gonyaulax polyedra is accurate to within 2 min/day. On successive days following the transfer to constant conditions, however, the glow exhibits a progressively broader waveform, implying that individual clocks in the population are drifting out of synchrony. Analysis of the glow waveform suggests that the standard deviation in circadian period among individual clocks is about 18 min and that the period of a given clock varies by less than this from one day to the next.

Animals↗
PubMed1976

Dinoflagellate bioluminescence: a comparative study of invitro components.

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.

Animals↗
PubMed1976

Membranes and molecules in circadian systems.

A membrane clock model involving ions and ion transport is compatible with the limit cycle concept, biochemical studies, and the idea of phase shifting by ion gating. It provides an explanation for temperature compensation, and, by assuming that oscillating ion concentrations regulate the many different biochemical and physiological rhythms, it explains how diverse systems can be controlled by a single oscillatory mechanism. How ions control ion transport and which membranes are involved in the clock are two questions we have begun to explore.

Animals↗
PubMedDate not supplied

Cellular autonomy of the Gonyaulax circadian clock.

Because of the long term persistence of free-running circadian rhythms in populations of unicells, several investigators have considered, but not demonstrated, a possible role for intercellular interaction in maintaining synchrony between individual cells. The experiments described here were designed to test more critically the possibility that there is interaction between cells, including those possessing only small phase differences. None was detected; the bioluminescent glow of the mixed cultures matched the algebraic sum of the independent control cultures.

Animals↗