• 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.

• BMB Reports
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• 제29권4호
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• pp.372-379
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• 1996

Components I and II (CI&II) are major phosphoproteins in the frog rod outer segments (ROS) of retina, whose phosphorylation is light- and cyclic nucleotide-dependent. Although it was reported that CI & II could be chemically cross-linked to ${\beta}{\gamma}-subunit$ of transducin (${\beta}{\gamma}_t$), it was not clear whether CI&II physically interact with ${\beta}{\gamma}_t$, under native conditions. CI&II extracted by hypotonic washing fo ROS membranes showed an overlapped migration with ${\beta}{\gamma}_t$, in sucrose density gradient centrifugation. The elution profile of CI&II in the peripheral membrane fractions from gel filtration chromatography also overlapped that of ${\beta}{\gamma}_t$. These hydrodynamic parameters indicate that the native molecular state of CI&II in the peripheral membrane fraction appears to be within a complex, most likely with ${\beta}{\gamma}_t$. CI&II coeluted with ${\beta}{\gamma}_t$, showed no phosphorylation by endogenous kinase which phosphorylates a serine of CI&II in other fractions. The purified CI&II were not able to inhibit trypsin-activated cGMP-phosphodiesterase, and CI&II were not recognized by a monoclonal antibody against the ${\gamma}-subunit$ of transducin, indicating that CI&II are not y-subunit of PDE or transducin. Thus, it is likely that native CI&II, which undergo a light-dependent phosphorylation/dephosphorylation cycle, can associate with ${\beta}{\gamma}$, in frog photoreceptor membranes, and the complex formation has an inhibitory effect on the endogenous phosphorylation of CI&II.

• 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.

• Journal of Photoscience
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• 제9권2호
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• pp.430-432
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• 2002

The changes in expression of copper-zinc superoxide dismutase (CuZn-SOD), manganese superoxide dismutase (Mn-SOD) and glutathione peroxidase (GPX) in light-damaged rat retinas were examined. Sprague-Dawley rats (male, 6-weeks-old) were maintained on a cyclic photoperiod (12 hours light and 12 hours darkness) for 2 weeks. The illumination intensity during the light period was 80 lux. To induce light damage to the retina, a high-intensity illumination (3000-lux) was applied to the animals for 24 hours. After light exposure, the animals were returned to cyclic lighting. Eyes were enucleated 12 and 24 hours after light exposure started or 1,3, and 7 days after light exposure ended. Eyes were fixed and embedded in paraffin wax. Tissues were cut into 4${\mu}{\textrm}{m}$-thick sections. Sections were immunostained using antibody against CuZn-SOD, Mn-SOD, GPX and 8-hydroxy-deoxyguanocine (8-OHdG) as oxidative stress marker. 8-OHdG was observed in the outer nuclear layer (ONL) and retinal pigment epithelium (RPE) during light exposure. In light-damaged retinas CuZn-SOD labeling was up regulated in the ONL and RPE. Mn-SOD labeling was up regulated in rod inner segments (RIS) during light exposure and that in the RPE was up regulated after exposure. GPX labeling was observed in rod outer segments (ROS) during light exposure. GPX labeling was also observed in the RPE during and after light exposure. All three enzymes were observed in the outer retina, which suffered light damage, but occurred in defferent layers except within the RPE, in which case all three were expressed. These enzymes may play complementary roles as protective factors in light-damaged retinas.

• Nuclear Engineering and Technology
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• 제30권6호
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• pp.541-554
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• 1998

A computer code COSMOS has been developed based on the CARO-D5 for the thermal analysis of LWR UO$_2$ and MOX fuel rod under steady-state and transient operating conditions. The main purpose of the COSMOS, which considers high turnup characteristics such as thermal conductivity degradation with turnup and rim formation at the outer part of fuel pellet, is to calculate temperature profile across fuel pellet and fission gas release up to high burnup. A new mechanistic fission gas release model developed based on physical processes has been incorporated into the code. In addition, the features of MOX fuel such as change in themo-mechanical properties and the effect of microscopic heterogeneity on fission gas release have been also taken into account so that it can be applied to MOX fuel. Another important feature of the COSMOS is that it can analyze fuel segment refabricated from base irradiated fuel rods in commercial reactors. This feature makes it possible to analyze database obtained from international projects such as the MALDEN and RISO, many of which were collected from refabricated fuel segments. The capacity of the COSMOS has been tested with some number of experimental results obtained from the HALDEN, RISO and FIGARO programs. Comparison with the measured data indicates that, although the COSMOS gives reasonable agreement, the current models need to be improved. This work is being performed using database available from the OECD/NEA.

• BMB Reports
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• 제37권2호
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• pp.260-267
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• 2004

Transducin (T), the heterotrimeric guanine nucleotide binding protein in rod outer segments, serves as an intermediary between the receptor protein, rhodopsin, and the effector protein, cGMP phosphodiesterase. Labeling of T with dansyl chloride (DnsCl) inhibited its light-dependent guanine nucleotide binding activity. Conversely, DnsCl had no effect on the functionality of rhodopsin. Approximately 2-3 mol of DnsCl were incorporated per mole of T. Since fluoroaluminate was capable of activating DnsCl-modified T, this lysine-specific labeling compound did not affect the guanine nucleotide-binding pocket of T. However, the labeling of T with DnsCl hindered its binding to photoexcited rhodopsin, as shown by sedimentation experiments. Additionally, rhodopsin completely protected against the DnsCl inactivation of T. These results demonstrated the existence of functional lysines on T that are located in the proximity of the interaction site with the photoreceptor protein.

• Restorative Dentistry and Endodontics
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• 제30권4호
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• pp.344-351
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• 2005

본 연구는 법랑소주의 말단과 측면에 대한 3단계, 2단계 및 단일 단계 접착제의 미세전단 결합강도를 상호 비교하였다. 발거된 상$\cdot$하악 대구치를 근, 원심 방향으로 1mm 두께가 되도록 절단하였다. 시편 중 협면과 설면 중앙부의 최 외층을 법랑소주의 말단이 노출된 시편으로 이용하였고, 내측에서 얻어진 시편을 법랑소주의 측면이 노출된 시편으로 이용하였다. 사용된 접착제에 따라 4개의 군 (1군 All-Bond 2, 2군: Single Bond, 3군: Tyrian SPE/One-Step Plus, 4군: Adper Prompt L-Pop)으로 분류하였다. 각 군당 법랑소주의 말단과 측면이 노출된 시편을 각각 7개씩 선택하여 각각의 접착제와 Tygon tube를 이용하여 복합레진을 접착한 후, universal testing machine에서 분당 1 mm의 crosshead speed의 전단하중을 가하여 미세전단 결합강도를 측정하였다. 각 군의 미세전단 결합강도를 통계학적으로 분석하여 다음과 같은 결과를 얻었다. 1 법랑소주 말단에 대한 미세전단 결합강도는 2군과 4군이 1군과 3군보다 통계학적으로 높게 나타났다 (p<0.05) 2. 법랑소주 측면에 대한 미세전단 결합강도는 2군은 1군, 3군, 4군보다 그리고 4군은 1군보다 통계학적으로 높게 나타났다 (p<0.05). 3. 모든 군에서 법랑소주 말단에 대한 미세전단 결합강도는 법랑소주 측면에 대한 결합강도보다 통계학적으로 높게 나타났다 (p<0.05).

• 한국어류학회지
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• 제29권3호
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• pp.218-223
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• 2017

한국산 담수어류 버들붕어의 눈을 관찰하고 시각을 담당하는 망막의 시각세포 구조를 광학현미경과 주사전자현미경을 이용하여 조사하였다. 버들붕어는 구형의 수정체를 보유하고 있었으며, 각막은 노란색으로 확인하였다. 눈은 $3.5{\pm}0.2mm$의 크기였으며 두장/안경비는 $31.1{\pm}5.0$으로 비교적 큰 눈을 가지고 있었다. 버들붕어의 망막은 $158.2{\pm}10.6{\mu}m$의 두께였으며 시각세포층에는 간상세포 ($57.3{\pm}1.3$), 동형 이중원추세포($33.9{\pm}3.7$) 및 단일원추세포($27.8{\pm}1.6$)로 구성되어 있었으며 횡단면을 확인한 결과 정방형의 모자이크 모델을 보유하고 있었다. 모든 시각세포는 내절과 외절의 구분이 뚜렷하였으며 간상세포가 원추세포보다 더 길어 원추세포들의 외절과 외절사이에 간상세포의 내절이 존재하였다. 간상세포의 외절은 망막 색소상피층 아래까지 신장되어 있었다. 전자현미경을 통해 미세구조를 확인한 결과 원추세포와 간상세포 모두 내절과 외절을 연결하는 배상극이 관찰되었으며 간상세포 및 동형 이중원추세포의 형태가 뚜렷하게 구분되었다. 시각세포의 횡단면을 관찰한 결과 짧은 단일원추세포를 기준으로 상하좌우에 동형 이중원추세포가 정방형 배열을 하고 있었다.

• Journal of Photoscience
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• 제9권2호
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• pp.246-248
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• 2002

Light is a major environmental signal for entrainment of the circadian clock, but little is known about the phototransduction pathway triggered by light-activation of photoreceptive molecule(s) responsible for the phase shift of the clock in vertebrates. The chicken pineal gland and retina contain the autonomous circadian oscillators together with the photic entrainment pathway, and hence they provide useful experimental model for the clock system. We previously demonstrated the expression and light-dependent activation of rod-type transducin $\alpha$-subunit (Gtl$\alpha$) in the chicken pineal gland. It is unlikely, however, that the pineal Gt$_1$$\alpha$ plays a major role in the photic entrainment, because the light-induced phase shift is unaffected by bloking the signaling function of Gt$_1$$\alpha$. Here, we show the expression of G 11 $\alpha$, an $\alpha$-subunit of another heterotrimeric G-protein, in the chicken pineal gland and retina by cDNA cloning, Northern blot and Western blot analyses. GIl$\alpha$-immunoreactivity was colocalized with pinopsin in the chicken pineal cells and it was found predominantly at the outer segments of photoreceptor cells in the retinal sections, suggesting functional coupling of G11 $\alpha$ with opsins in the both the tissues. By coimmunoprecipitation experiments using the retina, we showed the light- and GTP-dependent interaction between rhodopsin and G11 $\alpha$. Upon ectopic expression of a Gq/ 11-coupled receptor in cultured pineal cells, pharmacological (non-photic) activation of endogenous G11 induced phase-dependent phase shifts of the melatonin rhythm in a manner very similar to the effect of light. These results suggested opsin-G11 pathway contributing to the photic entrainment of the circadian clock.