• Applied Microscopy
• /
• 제25권4호
• /
• pp.115-123
• /
• 1995

This study was carried out to observe the functional ultrastructures of photoreceptor cells in frog(Rana catesbeiana) retina using transmission electron microscope. The photoreceptor cells are divided into two types-rod and cone cells-consist of outer and inner segment. The long outer segment of rod cell contains dense stacks of membrane and formed vertical and horizontal folds. The outer segment of cone cell is small, and vertical and horizontal folds are not exist. The electron dense cytoplasm of rod cell contains compact mitochondria, Golgi complexes, and endoplasmic reticula. The inner segment of cone cell shows low electron density and contains a large lipid droplet in the upper part of inner segment. In addition, cone cell contains many mitochondria, Golgi complexes. rough endoplasmic reticula, ribosomes and numerous glycogen particles. It is believed that these ultrastructural characteristics are closely associated with photoreceptive function of photoreceptor cells in frog retina.

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

• Applied Microscopy
• /
• 제47권4호
• /
• pp.238-241
• /
• 2017

A study on the visual cell and eyeball of the endemic Korean species Liobagrus mediadiposalis was investigated by light and electron microscopes. The retina of a small and 2 mm-diameter round eye was thin, $151.0{\pm}4.0{\mu}m$ and has two visual cells, a single cone and a rod cell. The single cone cells are short and thick, $18.0{\pm}0.9{\mu}m$ in length and $5.1{\pm}0.7{\mu}m$ (n=30) in diameter, while the rod cells are longer and thinner, $54.8{\pm}2.9{\mu}m$ in length and $3.3{\pm}0.6{\mu}m$ in diameter. The cone cells are seen an irregular and random mosaic pattern, and the rod cells are also randomly situated at between cone cells. As a rare phenomenon, such structure is one of characteristics reflecting the eye of a nocturnal and bottom-dwelling freshwater fish. The ultrastructure of visual cells was observed with scanning and transmission electron microscopy, both cone and rod cells are divided into an inner segment with numerous mitochondria and an outer segment with stacks of membrane discs.

• Journal of Photoscience
• /
• 제9권2호
• /
• pp.284-286
• /
• 2002

The inverted retina of the Onchidium dorsal eye (DE) is composed only of ciliary-type photoreceptor cells (CC's). The outer segment (OS) of the CC is a concentric lamellar structure consisting of many modified ciliary membranes and stains positively with anti-$\beta$-tubulin antibody. Near the base of the OS there are about 30 basal bodies each connecting individually to a cilium. The cilia are rod-shaped at the base, progressing upwards to a flattened sheet-like shape with increasing surface area. Three-dimensional analysis on serial sections demonstrates the ladle-shape of a modified cilium. Many modified cilia wrap around each other like the leaves of a cabbage. Nine pairs of microtubules (MT's) are located regularly in a ring at the base of the cilium, gradually losing their regular arrangement towards the periphery, where they separate into two subgroups that are contained within two swollen portions of a modified cilium. Within the CC of the Onchidium DE, MT's in the modified cilium exist as two poles extending longitudinally in a thin expanded ciliary membrane. This arrangement may support the photoreceptive OS and serve to maintain its structural integrity.

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

• Animal cells and systems
• /
• 제14권4호
• /
• pp.351-360
• /
• 2010

A new species of the Cletopsyllidae belonging to the genus Isocletopsyllus Huys and Lee, 1999 is described from the materials collected from subtidal sandy bottoms at Jeju Island and Ulleung Island, Korea. So far, only two species of the genus Isocletopsyllus, viz. I. tertius (Por, 1964) from Israel and I. quartus (Soyer, 1966) from Banyuls-sur-Mer (France) are recorded, both from the Mediterranean Ocean. The new species can be clearly distinguished from its congeners by the combination of the following characters: (1) female antennule with a large process on the outer margin of first segment, (2) caudal rami with a bulbous proximal inner expansion, and shorter than those of other species (about four times long as wide in the new species), (3) second segment of P1 exopod with a short rod-like inner seta, (4) sexual dimorphism presented in the second endopodal segment of male P2, not in exopod of P4, and (6) female P5 with a very long exopod with very short second outer seta. A table comparing the modifications of swimming legs in the family Cletopsyllidae Huys and Lee, 1999 is presented. This is the first record of this family from Korea.

• 한국어류학회지
• /
• 제27권4호
• /
• pp.257-262
• /
• 2015

한국고유종인 왕종개의 안구를 관찰하고 망막에 존재하는 시각세포의 구조를 광학현미경과 주사전자현미경을 이용하여 조사하였다. 왕종개의 안구는 $3.53{\pm}0.2mm$의 크기였으며 두장대 안경비율은 $14.08{\pm}0.7$이였다. 시각세포의 수직단면을 확인한 결과 망막은 여러 층으로 구성되어 있었으며 전체 망막의 두께는 $216.42({\pm}13.36){\mu}m$였으며, 시각세포의 핵이 존재하는 바깥핵층의 두께는 13.42 $({\pm}2.16){\mu}m$였다. 이형 이중 원추세포 중 긴 원추세포는 $26.42{\pm}1.7{\mu}m$의 길이였으며 직경은 $5.12{\pm}0.6{\mu}m$로 확인되었다. 짧은 원추세포는 $16.82{\pm}1.1{\mu}m$의 길이였으며 직경은 긴 원추세포와 유사한 $5.10{\pm}0.31{\mu}m$로 확인되었다. 간상세포는 길이 $40.13{\pm}2.4{\mu}m$였으며 직경 $3.95{\pm}0.4{\mu}m$로 확인되었다. 시각세포의 수평단면을 확인한 결과 이형 이중 원추세포가 규칙적인 배열로 인해 열 배열(row-type)의 모자이크 패턴으로 나타났다. 긴 원추세포와 짧은 원추세포가 하나의 쌍을 이루었으며 긴 원추세포는 내절이 절단되어 eosin에 염색되었으며 짧은 원추세포는 외절이 절단되어 hematoxylin에 염색되었다. 전자현미경을 통해 미세구조를 확인한 결과 내절과 외절로 구분되고 내절은 장타원형으로 확인되었다. 외절에는 디스크구조의 판상을 확인할 수 있었으며 내절과 외절을 연결해주는 배상극 (calyceal processes)들이 가장자리에 분포하고 있었다.

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

• Journal of Photoscience
• /
• 제9권2호
• /
• pp.427-429
• /
• 2002

We studied iron release from ferritin by irradiating the visible light, and then followed ferritin-mediated lipid peroxidation in the rod outer segment (ROS) fraction of the porcine retina. In the presence of several phosphorus compounds such as ADP and ATP, iron release from ferritin at pH 7.0 could be induced by irradiation of the visible light to the reaction mixtures. Furthermore, iron release from ferritin in the presence of ADP depended on the incubation time and the visible light irradiation. Moreover, we investigated lipid peroxidation level in the ROS fraction by two independent assay systems including the thiobarbituric acid (TBA) and ferrous oxidation/xylenol orange (FOX) methods. The visible light induced ferritin-mediated lipid peroxidation in the ROS fraction in time- and irradiance-dependent manners. In the dark condition, iron release and lipid peroxidation were not observed. Iron release from ferritin by irradiating the visible light may play an important role in the etiology of phototoxic injuries in vivo.

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