Hiroshi Niwa

Origin of the slow potential in the pineal organ of the rainbow trout

Abstract The light-induced hyperpolarizing slow potential picked up by a glass microelectrode from the pineal organ, epiphysis cerebri, of the fish is concluded to be a receptor potential, for the following two reasons: (1) the potential showed practically no area effect as compared with the S-potential of the retina; and (2) injection of procion yellow through the recording electrode revealed that the tip of the electrode was in fact located in the photoreceptor cell when the potential was recorded. The hyperpolarizing potential was accompanied by a resistance decrease that reached a maximum of about 5M Ω on illumination.

Spectral sensitivity and color vision of fish as indicated by S-potential

Abstract 1. 1. Black porgy, chidai and neko shark seem to be color blind, since no chromatic type of S-potential was recorded in their retinas. 2. 2. From the presence of the chromatic responses in the retina, the ability to discriminate colors is thought to exist in mullet, carp, goldfish, suzuki, bluegill, yellow-tail and sting ray, and is especially well developed in the first three. 3. 3. A luminosity response, having a maximum between 584 and 612 mμ, was only found in carp, goldfish, bluegill and mullet. The high percentage of the occurrence of this response in these fishes suggests that they are most sensitive to the wavelengths around 600 mμ, which are also the prevailing wavelengths in their usual habitats. 4. 4. A shift of the maximum L-response to shorter wavelengths was observed in marine fishes such as suzuki, yellow-tail, sting ray, black porgy, chidai and neko shark. This is explained in terms of the adaptation to the environment where light of shorter wavelengths prevails. 5. 5. The S-potential method is suggested as a useful way to investigate color vision and spectral sensitivity of the fishes, especially those which are not suitable for training or behavioral experiments.

Spectral sensitivity of a fish, Tribolodon Hakonensis (Günther), retina from two localities

Abstract o 1. The spectral sensitivities of the L-responses of S-potentials were studied in a fish, Tribolodon hakonensis (Gunther), retina. 2. Results of this survey show that the two groups of fresh water ugui taken from two widely separated locations give different L-responses. 3. One of these gave exclusively the L-response having its maximum at around 548 nm (as in animals possessing retinene1-dominated retina), whereas the other showed a predominance of the L-response having its maximum at around 612 nm (as in the retinene2-dominated retina of Tinca). 4. The possible implications of the results are discussed in relation to visual pigment changes that occur in several species of fish taken from different locations. And also this difference between two groups of ugui is probably correlated to the spectral characteristics of their environmental light.

Spectral Sensitivy Curves of the Skipjack Tuna and the Frigate Mackerel

The spectral sensitivity curves have been obtained by means of the L-response of S-potential for the skipjack tuna (Katsuwonus pelamis), and for the frigate mackerel (Auxis thazard). The sensitivity curve is always maximal at 497 nm and, in addition, differed little from the Dartnalls nomogram curve with its λmas at the same position. That this curve might reflect the activity of the one photoreceptor, presumably the cone, in spite of the close agreement with the absorption spectrum of the rod pigment, rhodopsin is dis-cussed in the paper. The results are also explained in terms of light adaptation to the environment where light of shorter wavelengths prevails.

S-potential-spectral sensitivity in two gobies, Acanthogobius flavimanus and Glossogobius olivaceus (gobiidae)

1. 1. The S-potentials recorded intracellularly from the mixed retina of both Acanthogobius flavimanus and Glossogobius olivaceus probably arise from the small horizontal cells situated directly below the layer of receptors. 2. 2. The L-responses hyperpolarize in response to light, regardless of stimulus wavelength, and the responses in photopic conditions are found to be subserved by a single photopigment with γmax = 584 nm. 3. 3. Together with L-response, C-response was recorded in these fishes. 4. 4. The present experiment cannot exclude the possibility that fishes must have two or more classes of receptors with different properties.