• Journal of Photoscience
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• 제7권1호
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• pp.1-4
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• 2000

The photosensory ciliates Blepharisma japonicum and Stentor coeruleus use the hypericin-derived pigments blepharismin and stentorin, respectively, as photoreceptor chromophores. Fluorescence quenching studies have shown that the first excited singlet state of hypericin and the purified chromophores blepharismin and stentorin can be deactivated by electron transfer to an acceptor molecule with a suitable reducing potential [1,2]. This paper reports the result of a series of photobehavioral experiments performed with the aim to ascertain if the same electron accepters which quench the photoreceptor pigment fluorescence in vitro may also compete with the native acceptor molecule in its natural physiological environment. Individual cell trajectories were examined before and after light stimulation, in the presence and in the absence of potential "in vivo" electron accepters, with a microvideo-recording apparatus. Our data, on Blepharisma cells, showed that as the negative reduction potential of the electron acceptor increases, a pronounced decrease in cell photoresponsiveness was detected. A dramatic effect on cell photoresponsiveness was noticed in the presence of 1,4-benzoquinone that has the lowest negative reduction potential. Such an effect on the percentage of photoreacting cells was moderate in the case of 1,4-naphthoquinone, with a relatively higher negative reduction potential. In the presence of benzophenone, which has the highest negative reduction potential, no significant effect on photoreacting cells was noticed. Our results can support the hypothesis that in the pigment granules such a light-induced charge transfer from excited blepharismin to a suitable electron acceptor triggers sensory transduction processes in B. japonicum.

• Ocean and Polar Research
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• 제39권2호
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• pp.149-158
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• 2017

The opsin family of light sensitive proteins family makes up are the universal photoreceptor molecules of all visual systems in the vertebrates including teleosts. They can change their conformation from a resting state to a signaling state upon light absorption, which activates the G-protein coupled receptor, thereby resulting in a signaling cascade that produces physiological responses. However, this species is poorly characterized at molecular level due to little sequence information available in public databases. We have investigated the opsin family of nocturnal cutlass fish using the whole transcriptome sequencing method. The opsin genes were cloned and its expression in the tissues and organs were examined by qPCR. We cloned 6 opsin genes (RRH, Opn4, Rh1, Rh2, VA-opsin, and Opn3) in retina and brain tissue. It contained the seven presumed transmembrane domains that are characteristic of the G-protein-coupled receptor family. However, short wavelength sensitive pigment (SWS) and long wavelength sensitive pigment (LWS) were not detected in this study. The mRNA expression of the 6 photoreceptor genes were detected in retina and peripheral tissue. Our studies will lead to further investigation of the photic entrainment mechanism at molecular and cellular levels in cutlass fish and can be used in comparative studies of other fishes.

• 대한의용생체공학회:학술대회논문집
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• 대한의용생체공학회 1998년도 추계학술대회
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• pp.295-296
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• 1998

With xeroradiography appearance, DR (Digital Radiography) system have been studying for X-ray detection using photoreceptor. Also detection method for receptor charge change have been developing variably. We use photoreceptor material of a-Se(Amorphous Selenium) with high DQE, high SNR(Signal to Noise Ratio) and high transformation efficiency of X-ray signals into electrical signals. After a-Se receptor is uniformly charged by using Arc discharge, X-ray is exposed. Then a-Se receptor produce subtle charge variation and MOSFET detect charge variations. The detected signal pass A/D converter and signal processing by PC. As results, the initial voltage is 8V. It has wide dynamic range needed digital radiography system. In this study, we obtained data with changing kVp(tube potential voltage) and fixed 8mAs(tube current by exposure time) in X-ray system. However MOSFET detector for X-ray signal is not tested X-ray mAs variations. But if MOSFET detector is tested X-ray mAs variation and exactly calibrated multichannel is made and noise-reduction is done, suitable DR system readout method will be done.

• 한국재료학회지
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• 제3권5호
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• pp.505-513
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• 1993

본 연구는 가시부 전영역에 감광하는 전자사진용 감광체를 만들기 위하여 400nm부근에 흡수파장을 갖는 sunfast yellow와 700nm부근에 흡수파장을 갖는 $\alpha$,$\beta$-copperphthalocyanine의 색소를 산화아연(ZnO)에 흡착분산시켰다. 각종 결합제(Binder)의 감도와 , 산화아연과 결합제와의 조성비에 따르는 변화실험의 결과 5.5:1에서 가장 좋은 결과를 나타냈다. 전자사진 감광체의 적합성을 확인하기 위하여 정전특성과 분광감도를 측정해 본 결과 sunfast yellow와 $\beta$-copper phthalocyanine을 혼합사용한 것이 가장 좋은 감도를 나타냈으며, 이 때 측정된 전자시진감도는 $E_{1:2}$=1440 luxㆍsec이었다. 또한 분광감도 측정결과는 가시부전역에 걸쳐 감도를 감광체임을 확인하였다.

• Clinical and Experimental Reproductive Medicine
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• 제37권3호
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• pp.199-206
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• 2010

망막 질환에서의 줄기세포 치료는 이전까지 치료가 불가능하다고 여겨졌던 환자들에서 시력을 향상시킬 수 있는 가능성 때문에 주목 받고 있다. 본문에서는 망막 전구세포의 분화를 위해 사용되는 태아 줄기세포, 배아줄기세포 및 성체줄기세포 등 다양한 세포 종류와, 내인적, 외인적 인자 및 이식 방법에 대해 논의하였다. 망막색소상피세포뿐만 아니라 시각세포 전구체로 성공적으로 분화시킨 실험적 연구가 보고되고 있다. 줄기세포기반치료는 아직 한계가 있지만 망막 질환 환자에서 시력을 회복하기 위한 보다 근본적인 치료 방법으로 기대되고 있다.

• Journal of Photoscience
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• 제9권2호
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• pp.275-277
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• 2002

We have recently found that a detergent-resistant raft like membrane (DRM) can be prepared from bovine rod outer segment membranes as a low-density buoyant fraction in sucrose density gradient ultracentrifugation. G protein (transducin) and its effector enzyme (phosphodiesterase: PDE) drastically change their affinities to DRM in the process of phototransduction. We report here that the recruitment of transducin and/or $^2$PDE to DRM has close relationship with their states in signal transduction. Active T$\alpha$/PDE-complex has a high affinity to DRM, whereas inactive transducin, or inactive PDE are excluded from DRM. Active T$\alpha$/PDE-complex seems to bind to a GTPase activating protein (GRS9) in multi- protein complexes localized on DRM. Physiological significance of the multi-protein complex on the raft-like membrane in vertebrate phototransduction would be discussed.

• Journal of Photoscience
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• 제9권2호
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• pp.17-20
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• 2002

We have cloned a cDNA for an opsin (Boceropsin) from the silkworm larval brain which was suggested to contain the photoperiodic receptor. Its deduced amino acid sequence was composed of 381 amino acids and included amino acid residues highly conserved in insect visual pigments. This opsin belonged to the long wavelength photoreceptor group of insect opsins, and are presumed to be photoperiodic receptor. RT-PCR analysis revealed that Boceropsin mRNA is expressed in the larval brain, but not in the subesophageal (Sg) and thoracic ganglion. Immunohistochemical analyses demonstrated that Boceropsin protein is present bilaterally in some defined cells localized in the brain of the Bombyx larva. Boceropsin was considered not to be involved in the circadian photoreception, because carotenoids are not indispensable for the photoreception and formation of circadian rhythms in the silkworm.

• Journal of Photoscience
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• 제9권2호
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• pp.47-50
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• 2002

Raft is a distinctive membrane domain enriched in a certain class of lipids, cholesterol, and proteins observed on the plasma membrane. Growing evidence has revealed that such membrane domains play key roles in signal transduction, fertilization, development, transmitter release, and so on. Recently, we have isolated raft-like detergent-resistant membrane (DRM) fraction from bovine photoreceptor rod outer segments. Transducin and its effecter, cGMP-phosphodiesterase, elicited stimulus-dependent translocation between detergent-soluble membrane and DRM. This suggested potential importance of such distinct membrane domains in vertebrate phototransduction. Here, we will discuss physiological meaning of the translocation of major components of cGMP cascade to raft-like membrane in phototransduction. We would like to propose a hypothesis that raft-like membrane domains on the disk membrane are the place where cGMP cascade system could be quenched.

• Rapid Communication in Photoscience
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• 제3권3호
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• pp.53-55
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• 2014

The shade avoidance syndrome is a morphological and physiological response when plants are exposed to shade. Recent work in Arabidopsis had begun to define the molecular components of the shade avoidance syndrome in dicotyledonous model plant. However, little is known about the shade avoidance response networks in agriculturally important monocotyledon crops such as rice. Here, we found that the degree of bending at the lamina joint is inversely proportional to the R:FR ratio. To elucidate which phytochrome is involved in this response, we did lamina joint inclination assay with the rice phytochrome-deficient mutants (osphyA, osphyB, and osphyC) and the wild type plants. Whereas the osphyA and osphyC knockout mutants bent at the lamina joint in the far-red rich condition as the wild type plants, the osphyB knockout mutants no longer bent at the lamina joint in the far-red rich condition. These results suggest that PHYB acts as a sole photoreceptor in the lamina joint inclination response in rice.

• BMB Reports
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• 제48권4호
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• pp.193-199
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• 2015

Degenerative retinal diseases affect millions of people worldwide, which can lead to the loss of vision. However, therapeutic approaches that can reverse this process are limited. Recent efforts have allowed the possibility of the stem cell-based regeneration of retinal cells and repair of injured retinal tissues. Although the direct differentiation of pluripotent stem cells into terminally differentiated photoreceptor cells comprises one approach, a series of studies revealed the intrinsic regenerative potential of the retina using endogenous retinal stem cells. Muller glial cells, ciliary pigment epithelial cells, and retinal pigment epithelial cells are candidates for such retinal stem cells that can differentiate into multiple types of retinal cells and be integrated into injured or developing retina. In this review, we explore our current understanding of the cellular identity of these candidate retinal stem cells and their therapeutic potential for cell therapy against degenerative retinal diseases. [BMB Reports 2015; 48(4): 193-199]