. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. SPAWNING OP CIONA INTESTINALIS 227 tion spectrum, the resolution attained by our system is not sufficient to do more than suggest that cytochrome c, or some other hemoprotein, may be the receptor material. The role of hemoproteins in photobiological processes has been extensively investigated by Arvanitaki and Chalazonitis (1949, 1960, 1961). These workers, studying the effect of monochromatic light on the visceral ganglion of the gastropod Aplysia, have demonstrated that two chromophores are involved in light reception as m
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. SPAWNING OP CIONA INTESTINALIS 227 tion spectrum, the resolution attained by our system is not sufficient to do more than suggest that cytochrome c, or some other hemoprotein, may be the receptor material. The role of hemoproteins in photobiological processes has been extensively investigated by Arvanitaki and Chalazonitis (1949, 1960, 1961). These workers, studying the effect of monochromatic light on the visceral ganglion of the gastropod Aplysia, have demonstrated that two chromophores are involved in light reception as measured by the electrical activity of isolated neurons. These pigments seem to act in antagonistic ways upon absorption of light. One pigment, a carotene- protein, generally produces a hyperpolarization of the membrane potential and c 5 o o» c o •o c in O «. 400 490 Wavelength 580 610 in FIGURE 2. A comparison of the absorption spectrum of cytochrome c (solid line) with the action spectrum for spawning of Ciona intestinalis (dashed line). inhibition of spiking. The other pigment, a heme-protein, produces a membrane depolarization and the initiation of spiking. The pigments are contained in granules just below the plasma membrane of the nerve cells, imparting a reddish hue to the cells. It is hypothesized (Chalazonitis, 1964) that the heme-protein, upon absorbing light, may pass an electron to the carotene-protein, thereby acting as a photoconductor. This transfer of electrons within the membrane is then visualized as opening channels for ionic flow. Thus a generator current is initiated which, if of sufficient intensity, may initiate action potentials. It is tempting to suggest that light absorbed by heme-proteins in Ciona may trigger a similar chain of events leading eventually to spawning. This, of course, implies absorption of light and action at the neuronal level. While it is true that the neural ganglion and numerous nerves of Ciona were illuminated in these experimen
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
