File:The Biological bulletin (20190671490).jpg

Title: The Biological bulletin
Identifier: biologicalbullet182mari (find matches)
Year: [1] (s)
Authors: Marine Biological Laboratory (Woods Hole, Mass. ); Marine Biological Laboratory (Woods Hole, Mass. ). Annual report 1907/08-1952; Lillie, Frank Rattray, 1870-1947; Moore, Carl Richard, 1892-; Redfield, Alfred Clarence, 1890-1983
Subjects: Biology; Zoology; Biology; Marine Biology
Publisher: Woods Hole, Mass. : Marine Biological Laboratory
Contributing Library: MBLWHOI Library
Digitizing Sponsor: MBLWHOI Library

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VISUAL PIGMENTS IN BLACK. SEA BASS 139
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Figure 1. Black sea bass photoreceptors viewed in infrared illumination in the recording microspectro- photometer. The images were captured on video tape and subsequently photographed from a video monitor display. A. Double cone in lateral view, just below a rod outer segment. B. Double cone with unequal outer segments. C. Double cone in a rare orientation, with overlapping outer segments. D. Single cone, proximal to retinal fragments. All four panels have equal magnification and the bar length represents 10 Mm. Double cones Every outer segment belonging to double cones was transversely dichroic due to the presence of a bleachable pigment. Representative spectra are shown in Figures 3 and 4, and spectral data are presented in the lower part of Table I. The A and BD spectra of Figure 3 were derived from one member of double cones. The spectra of Figure 4 were obtained from overlapping outer segments of dou- ble cones (see panel C of Fig. 1). Note the increased spec- tral absorbance in Figure 4A as compared to that in Figure 3A. The idea we illustrate here is that, when the two outer segments overlap laterally, the transversely scanned ab- sorbance nearly doubles, as it should if the two members are equivalent. However, while the A and BD spectra in- crease in proportion when measured from two, instead of one member, the Xmax and the HBW remain virtually unchanged. This can happen only if the same pigment is contained in both members. There was no evidence for the presence of a second pigment in any of the double cones. Rods As is common in teleost retinas, the rods of the black sea bass are numerous; the outer segments are of variable length and slender, with a diameter of 1 ^m or less. Re- cordings from multiple rods yielded A, BD, and LD spec- tra indicative of a "typical" rhodopsin. Trace B in Figure 5 was derived from such absorbance spectra. The HBW of the tt-band of the rod absorbance spectra were within experimental error of the value obtainable from other rhodopsins (such as amphibian or monkey), and this pig- ment should, therefore, also be based on vitamin A,. Traces A and C in Figure 5 depict the normalized absor- bance spectra of the cone pigments. The two cone pigment spectra flank the rod pigment spectrum on the longwave and shortwave sides by nearly the same distance on the wavelength scale. Dichroic ratio and transverse specific density The algebraic relationships necessary to determine cel- lular dichroic ratios from the A and LD spectral mea-

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