Simulation of Bioluminescence in Dinoflagellates by Controlled Pressure Changes PDF Download
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Author: T. Q. Donaldson
Publisher:
ISBN:
Category :
Languages : en
Pages : 9
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Bioluminescence in two species of dinoflagellates, Pyrocystis lunula and Gonyaulax polyedra, was stimulated when small pressure changes occured. At an initial pressure of 1 atm, a pressure decrease rate of 0.25 + or - 0.04 atm/s was the mean decrease threshold for P. lunula. Small variations in this threshold occured at a higher initial pressure and at different times during the circadian cycle. Pressure decreases were much more effective than pressure increases. For G. polyedra, a pressure change rate of at least 0.95 atm/s was required to stimulate bioluminescence. Pressure increases and decreases were both effective, but decreases were more effective than increases. The variation in results did not lend itself to statistical analysis.
Author: T. Q. Donaldson
Publisher:
ISBN:
Category :
Languages : en
Pages : 9
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Book Description
Bioluminescence in two species of dinoflagellates, Pyrocystis lunula and Gonyaulax polyedra, was stimulated when small pressure changes occured. At an initial pressure of 1 atm, a pressure decrease rate of 0.25 + or - 0.04 atm/s was the mean decrease threshold for P. lunula. Small variations in this threshold occured at a higher initial pressure and at different times during the circadian cycle. Pressure decreases were much more effective than pressure increases. For G. polyedra, a pressure change rate of at least 0.95 atm/s was required to stimulate bioluminescence. Pressure increases and decreases were both effective, but decreases were more effective than increases. The variation in results did not lend itself to statistical analysis.
Author: Thomas Quinton Donaldson
Publisher:
ISBN:
Category : Bioluminescence
Languages : en
Pages : 166
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Author: Kristine Holderied
Publisher:
ISBN:
Category : Bioluminescence
Languages : en
Pages : 80
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Bioluminescence in a dinoflagellate species, Pyrocystis lunula, was stimulated by controlled, repeated pressure changes. Pressure pulses of a two-second duration were used to determine their effect on stimulated bioluminescene. Observations of organism sensitivity in response to the circadian rhythm, light phase, and cell fatigue were also made. The pressure change was affected by valve-regulated compressed air. The luminescence was detected with a photomultiplier tube. The mean threshold for luminescence in Pyrocystis lunula was found to be 5.10 + or - 1.70 psi. Pressure decreases were found to be much more effective than pressure increases. Three other rates of pressure change were investigated and a rough correlation was established between higher rates of pressure change and slightly lower threshold levels. Qualitative observations indicated that increased rates of pressure change were also associated with higher initial flashes and faster fatigue times. Pulse length appeared not to affect the stimulable luminescence to any significant degree. Measurements made at various times in the scotophase revealed a relatively constant, high level of light output, while only minimal, if any, light ouput was detected in the photophase. The resulting threshold level was applied to a pressure field model around a submerged cylinder and the probable location of bioluminescence was predicted.
Author: David Lapota
Publisher:
ISBN:
Category : Bioluminescence
Languages : en
Pages : 228
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Category : Biology
Languages : en
Pages : 24
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Author:
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ISBN:
Category : Biology
Languages : en
Pages : 472
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Author: Wayne E. Esaias
Publisher:
ISBN:
Category : Bioluminescence
Languages : en
Pages : 152
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To provide further information on the occurrence and geographical variations of bioluminescent capabilities of marine dinoflagellates, forty species, representing twelve genera, of dinoflagellates from Yaquina Bay, Oregon, were examined for bioluminescence as single cell isolates. Seventeen species from the genera Ceratium (1 sp.), Gonyaulax (3 sp.), and Peridinium (13 sp.) were found to be bioluminescent. Ceratium fusus was the only member of the genus found to emit light; G. triacantha was found to be non-bioluminescent. The total photon emission of each luminescent species is reported. Values ranged from 1.05 x 1010 photons per P. depressum to 2.1 x 1O7 photons per G. digitale. As a taxon, the genus Peridinium emitted more light by an order of magnitude than did Ceratium or Gonyaulax. Comparisons with previous reports are made. Photoinhibition of the mechanical receptor mechanism is largely responsible for orders of magnitude diel variations of stimulable bioluminescence in the auxotrophic dinoflagellates. The mechanically stimulable bioluminescence of members of the Gonyaulax catenella group can be photoinhibited completely by exposure to as little as 1013 quanta/cm2 delivered as a pulse of width between 0.1 and 10 seconds. There is an initial time lag of one minute, followed by a first order decay to approximately one percent of the bioluminescence of unexposed controls. The half time of this decay is only 50 seconds. Action spectra for photoinhibition in Gonyaulax catenella, G. acatenlla, and G. tamarensis revealed a single absorption band with a maximum at 562 nm. Photoinhibition appears to raise the threshold of sensitivity of the shear receptor mechanism. Chemically stimulable bioluminescence is unaffected by these brief exposures to light. Grazing experiments were conducted with three calanoid copepods and three species of bioluminescent dinoflagellates, using procedures which yielded samples of cultures with high and low capacities for mechanically stimulable bioluminescence. In all cases the ingestion rates were lower for the high bioluminescent capacity samples than for the samples having a reduced bioluminescent capacity. These results indicate that dinoflagellate bioluminescence has survival value as a defense against copepod grazing. Of several possible mechanisms, we propose that the flash is a visual, protean display which startles or confuses the copepod sufficiently to allow the dinoflagellate to escape. The net evolutionary value is that predation would be reduced on a dinoflagellate population as a whole.
Author: David Lapota
Publisher:
ISBN:
Category : Science
Languages : en
Pages :
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Seasonal Changes of Bioluminescence in Photosynthetic and Heterotrophic Dinoflagellates at San Clemente Island.
Author: Charlotte L. J. Marcinko
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Author:
Publisher:
ISBN:
Category : Government reports announcements & index
Languages : en
Pages : 1522
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