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Y Shichida

Publications and source records attributed to Y Shichida.

At least 91 records · Page 5Linked to original sources
PubMed1990

Localization of iodopsin in the chick retina during in vivo and in vitro cone differentiation.

Using highly specific antibodies against a chick red-sensitive cone pigment, iodopsin, we investigated the localization of iodopsin in the developing and mature chick retina. The chick retina contains several different photoreceptor types, including a rod, a double cone with a principal and accessory cone, and four different types of single cones. Immunocytochemical observations revealed that outer segments (OS) of one of the single cones (type 1) and both cells of the double cone were strongly immunoreactive to anti-iodopsin antibodies. The Golgi regions and small vesicular structures in the inner segments (IS) of these cells also were intensely stained, indicating a continuous synthesis of iodopsin and its addition to the newly formed cone OS. In the differentiating cones of the developing but immature chick retina, iodopsin immunoreactivity was found at the plasma membranes of both the IS and the terminals (pedicles). This suggests that unidirectional transport of iodopsin to the outer segment may be established during cone differentiation. Immunostaining in the outer plexiform layer (OPL) produced two bands, suggesting that the pedicles of the double cones and type 1 single cones terminate at different positions in this layer. Application of the antibodies to a cell culture system of the chick retina revealed that cells immunoreactive to anti-iodopsin differ slightly in morphology from those reactive with anti-rhodopsin. Since antibodies to iodopsin and rhodopsin stained different types of photoreceptors in the intact chick retina, it will be possible to analyze cell lineage of rods and cones in vitro by use of these antibodies.

Animals↗
PubMed1989

Effect of chloride ion on the thermal decay process of the batho intermediate of iodopsin at low temperature.

The photochemical and the subsequent thermal behaviors of iodopsin (Cl(-)-bound form) and N-iodopsin (iodopsin whose Cl- was replaced by NO3-) in CHAPS-phosphatidylcholine (PC) were studied by low-temperature spectrophotometry. Irradiation of the iodopsin preparation at -185 degrees C produced a photo-steady-state mixture composed of iodopsin, bathoiodopsin, and isoiodopsin. Bathoiodopsin was thermally reverted to the original iodopsin. These results were almost the same as those reported previously [Yoshizawa, T., & Wald, G. (1967) Nature 214, 566-571] in which iodopsin was extracted with 2% digitonin. Therefore, photochemical and subsequent thermal behaviors of iodopsin were independent of the detergent to solubilize iodopsin. Irradiation of N-iodopsin at -185 degrees C produced the similar photo-steady-state mixture. However, N-bathoiodopsin was thermally converted to the next intermediate, presumably N-lumiiodopsin. These results suggest that the batho-lumi transition of iodopsin at low temperature is likely to be inhibited by the Cl- bound to the protein moiety of iodopsin, while at room temperature the Cl- bound to iodopsin could be released on the conversion process of batho- to lumiiodopsin.

Animals↗
PubMed1989

Mechanism of isomerization of rhodopsin studied by use of 11-cis-locked rhodopsin analogues excited with a picosecond laser pulse.

Primary photochemical behaviors of cattle rhodopsin analogues (Rh5 and Rh7) having cyclopenta- and cycloheptatrienylidene 11-cis-locked retinals (Ret5 and Ret7, respectively) were studied by excitation with a picosecond laser pulse (wavelength 532 nm; duration 21 ps). Picosecond absorption and fluorescence measurements of Rh5 showed formation of only a long-lived excited singlet state (tau l/e = 85 ps). The excited state of the retinal analogue having a five-membered ring was stabilized in protein (Rh5) more than in solvent (protonated Schiff base of Ret5; PSB5). Excitation of Rh7 produced two ground-state photoproducts, Rh7 (580) and Rh7 (630). According to the analysis of photon density dependency, Rh7 (580) was a single-photon product of Rh7, while Rh7 (630) was the photoproduct of Rh7 (580). Fluorescence emitted from a seven-membered ring system like Rh7 or a protonated Schiff base of Ret7 (PSB7) was weaker than that in a corresponding five-membered ring system, especially in protein (Rh7). The difference in photoreaction between Rh5 and Rh7 may originate from the difference in fixation of the 11-cis form. On the basis of the spectral and kinetic similarities between Rh7 (580) and photorhodopsin, a precursor of bathorhodopsin, it was proposed that both have twisted all-trans chromophores in the way of the isomerization. The protein moiety of rhodopsin which fixes the chromophore at both ends seems to accelerate the rotation of the C11-C12 double bond and to prevent it from going through relaxation processes other than the isomerization. This may be a plausible reason why rhodopsin has a large quantum yield (0.67).

Animals↗
PubMed1989

Absolute absorption spectra of batho- and photorhodopsins at room temperature. Picosecond laser photolysis of rhodopsin in polyacrylamide.

Picosecond laser photolysis of rhodopsin in 15% polyacrylamide gel was performed for estimating absolute absorption spectra of the primary intermediates of cattle rhodopsin (bathorhodopsin and photorhodopsin). Using a rhodopsin digitonin extract embedded in 15% polyacrylamide gel, a precise percentage of bleaching of rhodopsin after excitation of a picosecond laser pulse was measured. Using this value, the absolute absorption spectrum of bathorhodopsin was calculated from the spectral change before and 1 ns after the picosecond laser excitation (corresponding to the difference spectrum between rhodopsin and bathorhodopsin). The absorption spectrum of bathorhodopsin thus obtained displayed a lambda max at 535 nm, which was shorter than that at low temperature (543 nm) and a half band-width broader than that measured at low temperature. The oscillator strength of bathorhodopsin at room temperature was smaller than that at low temperature. The absolute absorption spectrum of photorhodopsin was also estimated from the difference spectrum measured at 15 ps after the excitation of rhodopsin (Shichida, Y., S. Matuoka, and T. Yoshizawa. 1984. Photobiochem. Photobiophys. 7:221-228), assuming a sequential conversion of photorhodopsin to bathorhodopsin. Its lambda max was located at approximately 570 nm, and the oscillator strength was smaller than those of rhodopsin and bathorhodopsin.

Acrylic Resins↗
PubMed1989

Monoclonal antibodies to chicken iodopsin.

The protein moiety of chicken iodopsin, R-photopsin, was purified from the chicken retina using a sucrose flotation method followed by two steps of column chromatography. Apparent molecular weights of R-photopsin and scotopsin (the protein moiety of chicken rhodopsin), which was partly purified in the process of purification of R-photopsin, were estimated to be 34,000 and 36,000, respectively, by sodium docecylsulfate-polyacrylamide gel electrophoresis. Using the purified R-photopsin as an antigen, four kinds of hybridoma cells which secreted monoclonal antibodies specific for R-photopsin and iodopsin were prepared. The antibodies thus obtained reacted with neither other chicken cone visual pigments nor rhodopsin as analyzed by immunoblots and immunoprecipitation methods. All the monoclonal antibodies stained the majority of the cone outer segments in chicken retina, while an antiserum raised against cattle rhodopsin stained the rod outer segments as well as some cone outer segments in the retina.

Animals↗
PubMed1989

Dependency of photon density on primary process of cattle rhodopsin.

The primary photochemical reactions of cattle rhodopsin suspended in H2O or D2O were compared between excitation with both a weak and an intense picosecond laser pulse (wavelength, 532 nm; duration, 25 ps) at room temperature. The time-dependent change of absorbance at about 575 nm demonstrated that photohodopsin, a precursor of bathorhodopsin, was produced immediately after the excitation with a weak picosecond laser pulse. It decayed to bathorhodopsin with a time constant of 45 ps which is close to the value reported previously [Shichida et al., (1984) Photobiochem. Photobiophys., 7, 221-228]. No deuterium effect was observed in this process. Excitation with an intense laser pulse induced instantaneous increase of the absorbance at about 575 nm and remained at almost constant level on the picosecond time scale, which was in good agreement with the pioneering work [Busch et al., (1972) Proc. Natl. Acad. Sci., USA, 69, 2802-2806]. No deuterium effect was observed in this photochemical process.

Animals↗
PubMed1988

9,13-dicis-rhodopsin and its one-photon-one-double-bond isomerization.

Incubation of purified 9,13-dicis-retinal with cattle opsin in 2% digitonin at 20 degrees C produced two pigments, one unstable (lambda max 478 nm) and the other stable (lambda max 485 nm) in hydroxylamine. The two pigments exhibited different characteristics. HPLC analysis revealed that the chromophores of these pigments have respectively 9,13-dicis and 9-cis geometries. Under various conditions the amount of 9,13-dicis-rhodopsin formed never exceeded 30% of the total pigments. The addition of 9,13-dicis-retinal to the ROS suspension containing opsin produced 9-cis-rhodopsin in 97% yield. Irradiation of the 9,13-dicis-rhodopsin mainly produced 13-cis-retinal, while 9-cis-rhodopsin produced the all-trans isomer. These results demonstrated that the one-photon-one-double-bond isomerization process took place in 9,13-dicis-rhodopsin.

Animals↗
PubMed1987

Electrostatic interaction between retinylidene chromophore and opsin in rhodopsin studied by fluorinated rhodopsin analogues.

Photochemical reactions of fluorinated rhodopsin analogues (F-rhodopsins) prepared from 10- or 12-fluorinated retinals (10- or 12-F-retinals) and cattle opsin were investigated by means of low-temperature spectrophotometry. On irradiation with blue light at liquid nitrogen temperature (-191 degrees C), the F-rhodopsins were converted to their respective batho intermediates. On warming, they decomposed to their respective fluororetinals and cattle opsin through lumi and meta intermediates. There was a difference in photochemical behavior between batho-12-F-rhodopsin and batho-10-F-rhodopsin. Upon irradiation with red light at -191 degrees C, batho-12-F-rhodopsin was converted to a mixture of 12-F-rhodopsin and 9-cis-12-F-rhodopsin like that of the natural bathorhodopsin, whereas batho-10-F-rhodopsin was not converted to 9-cis-10-F-rhodopsin but only to 10-F-rhodopsin. This fact suggests that the fluorine substituent at the C10 position (i.e., 10-fluoro) of the retinylidene chromophore may interact with the protein moiety during the process of isomerization of the chromophore or in the state of the batho intermediate. On irradiation with blue light at -191 degrees C, 9-cis-10-F-rhodopsin was converted to another bathochromic intermediate that was different in absorption spectrum from batho-10-F-rhodopsin. 9-cis-10-F-rhodopsin was practically "photoinsensitive" at liquid helium temperature (-265 degrees C), whereas 10-F-rhodopsin was converted to a photo-steady-state mixture of 10-F-rhodopsin and batho-10-F-rhodopsin. The specific interaction between the fluorine atom at the C10 position of the retinylidene chromophore and the opsin was discussed in terms of electrostatic interactions.

Animals↗
PubMed1984

Studies on structure and function of rhodopsin by use of cyclopentatrienylidene 11-cis-locked-rhodopsin.

The photochemical reaction of cyclopentatrienylidene 11-cis-locked-rhodopsin derived from cyclopentatrienylidene 11-cis-locked-retinal and cattle opsin was spectrophotometrically studied. The difference absorption spectrum between the cyclopentatrienylidene 11-cis-locked-rhodopsin and its retinal oxime had its maximum at 495 nm (P-495). Irradiation of P-495 at -196 degrees C with either blue light or orange light caused no spectral change, supporting the cis-trans isomerization hypothesis for formation of bathorhodopsin. Upon irradiation of P-495 at 0 degree C with orange light, however, its absorption spectrum shifted to a shorter wavelength owing to formation of a hypsochromic product. The difference absorption spectrum between this product (P-466) and its retinal oxime showed its maximum at 466 nm. Analysis of retinal isomers by high-performance liquid chromatography showed that this spectral shift was not accompanied by photoisomerization of the chromophore. P-466 could almost completely be photoconverted to the original pigment (P-495) by irradiation at 0 degree C with blue light with little formation of the other isomeric form of its chromophore. The alpha-band of the circular dichroism spectrum of P-495 was very small in comparison with that of rhodopsin, while that of P-466 was comparable to it. These facts suggest that P-495 has a planar conformation in the side chain of the chromophore and that P-466 has a twisted one, probably at the C8-C9 single bond. Cyclic-GMP phosphodiesterase in frog rod outer segment was activated by neither P-495 nor P-466. This result suggests that the isomerization of the retinylidene chromophore of rhodopsin is indispensable in the phototransduction process.

3',5'-Cyclic-GMP Phosphodiesterases↗
PubMed1984

Formation of hypsorhodopsin at room temperature by picosecond green pulse.

Excitation of squid rhodopsin with a single laser pulse (532 nm, 25 ps) at 18 degrees C yielded photorhodopsin, a precursor of bathorhodopsin. In the linear region, no relation between amount of photorhodopsin and excitation-energy hypsorhodopsin was detected, while in a photon saturation region this was observed. The time constant of hypsorhodopsin to bathorhodopsin decay was about 125 ps. Dependencies of formation of photorhodopsin and hypsorhodopsin on the excitation energy suggest that hypsorhodopsins of squid and octopus are formed by a two-photon reaction. No cattle hypsorhodopsin was detected in our experimental conditions.

Animals↗
PubMed1984

Primary intermediates of rhodopsin studied by low temperature spectrophotometry and laser photolysis. Bathorhodopsin, hypsorhodopsin and photorhodopsin.

The primary photochemical processes of rhodopsin studied by low temperature spectrophotometry and picosecond laser spectroscopy in our group was summarized. Low temperature spectroscopic experiments demonstrated that the retinylidene chromophores of hypso- and bathorhodopsins are in a twisted all-trans forms. Excitation of rhodopsin with 532 nm laser pulse (width: 25 psec) yielded a new bathochromic photoproduct "photorhodopsin"; its spectrum was located at longer wavelengths than that of bathorhodopsin. Photorhodopsin decays to bathorhodopsin with time constants of about 200 psec in squid and 40 psec in cattle. Squid and octopus hypsorhodopsins were produced within 25 psec by high energy pulse, but not by low energy pulse. Thus hypsorhodopsin is produced by two photon reactions (sequential two photochemical reactions) and decayed to bathorhodopsin with time constant of 125 psec.

Animals↗