. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. Wavelength (nm) _c u —1 1 1 1 1 1 1 1 1 1 I r— 3SB 400 450 500 550 600 650 Wavelength (nm) Figure 4. Absorbance and linear dichroism spectra obtained simul- taneously from both outer segments (stacked one above the other) of a double cone in the black sea bass. A. Average absorbance. based on 16 scans ( + ); the solid curve is the product of Fourier smoothing: Xmax = 521 nm, HBW = 4010 cm"'. B. Linear dichroism from the corre- sponding structure, based on 16 scans (A); the dotted curve is the outcome of Fourier f
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. Wavelength (nm) _c u —1 1 1 1 1 1 1 1 1 1 I r— 3SB 400 450 500 550 600 650 Wavelength (nm) Figure 4. Absorbance and linear dichroism spectra obtained simul- taneously from both outer segments (stacked one above the other) of a double cone in the black sea bass. A. Average absorbance. based on 16 scans ( + ); the solid curve is the product of Fourier smoothing: Xmax = 521 nm, HBW = 4010 cm"'. B. Linear dichroism from the corre- sponding structure, based on 16 scans (A); the dotted curve is the outcome of Fourier filtering. The Xmax and the HBW are 525 nm and 3860 cm"1, respectively. J7, for example, G/B = , and in J9 it is With increasing depth in these types of water, the sea bass visual pigments are clearly out of tune. For the J5 water type, the parameters are probably within acceptable range to depths of 20 m (see Table II). At greater depths, however, the fitness of the pigments become questionable. For in- stance, in J5 at 50 m depth the Xqc50 and Xmax differences are nm, nm, and nm for the B, R, and G receptor types, respectively; the absolute Q, values are down six orders of magnitude with respect to those at 10 m, and the R/B, R/G, and G/B ratios yield , , and , respectively. Although we lack firm criteria by which to interpret these numbers, they probably indicate an intolerable mismatch of the pigments to this photic habitat. On the magnitude of the dichroic ratio in cones Ever since the discovery of linear dichroism in laterally viewed rods by Schmidt (1938), the phenomenon has been interpreted in terms of a structural anisotropy in the outer segments of vertebrate photoreceptors. A quantitative measure of this property is the cellular dichroic ratio, R, as was defined in an earlier section. The magnitude of R is an expression of structural "order"; , the larger the R, the more ordered is the disposition of the visual p
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