• 대한의용생체공학회:의공학회지
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• 제30권4호
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• pp.347-354
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• 2009

For the reliable transmission of meaningful visual information using prosthetic electrical stimulation, it is required to develop an effective stimulation strategy for the generation of electrical pulse trains based on input visual information. The characteristics of neuronal activities of retinal ganglion cells (RGCs) evoked by electrical stimulation should be understood for this purpose. In this study, for the development of an optimal stimulation strategy for visual prosthesis, we analyzed the neuronal responses of RGCs in rd1 mouse, photoreceptor-degenerated retina of animal model of retinal diseases (retinitis pigmentosa). Based on the in-vitro model of epiretinal prosthesis which consists of planar multielectrode array (MEA) and retinal patch, we recorded and analyzed multiunit RGC activities evoked by amplitude-modulated electrical pulse trains. Two modes of responses were observed. Short-latency responses occurring at 3 ms after the stimulation were estimated to be from direct stimulation of RGCs. Long-latency responses were also observed mainly at 2 - 100 ms after stimulation and showed rhythmic firing with same frequency as the oscillatory background field potential. The long-latency responses could be modulated by pulse amplitude and duration. From the results, we expect that optimal stimulation conditions such as pulse amplitude and pulse duration can be determined for the successful transmission of visual information by electrical stimulation.

• 한국안광학회지
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• 제12권4호
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• pp.133-139
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• 2007

Calretinin의 생리적 역할은 아직 확립되지 않았지만, 칼슘 buffer로서의 작용과 칼슘 중재의 신호 변환에 적극적으로 작용하고 있다. Calretinin은 인간의 망막에서 성체 광수용체 세포와 이극세포, 수평세포에서 칼슘의 수송과 칼슘의 생리적 buffering으로서의 역할을 하고 있다. 본 연구에서 한국관 박쥐의 망막의 내핵층과 신경절세포층에서 calretinin의 면역세포화학반응 신경세포들과 그 분포 양상을 조사하여 우리는 박쥐 망막에서 calretinin에 면역세포화학반응을 일으키는 AII 무축삭세포를 내핵층에서 그리고 신경절세포층에서는 신경절세포들을 확인할 수 있었다. 이번의 관찰연구는 우리의 이전 연구와 더불어 박쥐 시력의 풀리지 않는 문제와 박쥐비행의 기동성의 독특한 행동적인 측면들을 더욱 많이 이해하는데 필요하다고 생각한다.

• Applied Microscopy
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• 제25권4호
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• pp.9-16
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• 1995

Ultrastructure of stemmata(larval eye) of 5th-instar larval in cabbage butterfly, Pieris rapae L, was morphologically investigated with light microscope, scanning electron microscope and transmission electron microscope Six stemmata are on each side of the head. Stemmata V and VI have a Y-shaped sulcus on the surface of their corneal lenses, the others have a columnar shaped process and smooth globular surface. The visual type of stemmata is resembled a single ommatidium of compound eye. The dioptric apparatus are a biconvex shaped cornea and crystalline cone. As a photoreceptor, each stemmata consists of 7 retinular cells arranged into 2 tiers. The first ceil tier of 3 distal retinular cells has formed a V-shaped cup rhabdome and the second cell tier of 4 basal retinular cells has formed a H-shaped fused rhabdome. Each retinular cell filled with pigment granules and contained multivesiclular bodies, coated vesicle and common organelles. The peripheral parts of retinular cells are enveloped by neuroglia cells and retinular cells are surrounded by 3 corneagenous cells. The distal portions of the 3 corneagenous cells contact each other, but the Y-shaped stemmata is separated from each other immediately under the cornea. The 7 axons from each stemma congregate into a bundle and each 7-axon group joins to form a stemmatal nerve, consisting of 42 retinular axons.

• Journal of Photoscience
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• 제6권2호
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• pp.77-83
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• 1999

Calcium has a variety of functions in neuron and muscle cells and blood clotting, especially in the visual system where dark adapted rods cotransport with Na$\^$+/ into the cell. An influx of Ca$\^$++/ flows out of the cell through the Na$\^$+/-Ca$\^$++/ exchanger. By using a modified Using chamber in order to bring in vivo environment close, we have known that Ca$\^$++/ blocks the activity of guanylate cyclase, in consequence, having an effect on the amplitude of electroretinogram (ERG). We have measured the Ca$\^$++/, K$\^$+/, and Na$\^$+/ concentration in dark and light adapted bullfrog＇s (Rana catesbeiana) vitreous humor. The calcium concentration of the light adapted bullfrog＇s vitreous humor was higher than that of the dark adapted bullfrog＇s vitreous humor This means that ion activity between the photoreceptor and vitreous humor side is light dependent and we have found that a Ca$\^$++/ channel and Ca$\^$++/K$\^$+/ exchanger exist in the vitreous humor side. Taken together permeability of Ca$\^$++/, K$\^$+/ and K$\^$+/ ion internal limiting membrane faced in the vitreous humor side has light-dependent activity during the illumination.

• 센서학회지
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• 제13권3호
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• pp.188-194
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• 2004

With a remarkable advance in CMOS (complimentary metal-oxide-semiconductor) process technology, a variety of vision sensors with signal processing circuits for complicated functions are actively being developed. Especially, as the principles of signal processing in human retina have been revealed, a series of vision chips imitating human retina have been reported. Human retina is able to detect the edge and motion of an object effectively. The edge detection among the several functions of the retina is accomplished by the cells called photoreceptor, horizontal cell and bipolar cell. We designed a CMOS vision chip by modeling cells of the retina as hardwares involved in edge and motion detection. The designed vision chip was fabricated using $0.6{\mu}m$ CMOS process and the characteristics were measured. Having reliable output characteristics, this chip can be used at the input stage for many applications, like targe tracking system, fingerprint recognition system, human-friendly robot system and etc.

• Animal cells and systems
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• 제3권3호
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• pp.259-267
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• 1999

The expression of the neural cell adhesion molecule-180 (NCAM-180), which accumulates at contact sites between cells and may be responsible for the stabilization of cell contacts, was studied in the olfactory system and retina of developing and adult rats. From embryonic day 12 onwards, which was the earliest stage examined, the NCAM-180 pathway directing to the presumptive olfactory bulb was observed. In later stages, olfactory neurons and fasciculating axons in the olfactory epithelium and nerve fiber layer and glomeruli of the olfactory bulb expressed NCAM-180. From postnatal day 0, immunolabelling pattern of the olfactory epithelium and olfactory bulb were the same as that during later stages. NCAM-180 immunoreactivity was present on differentiating retinal cells and persisted on those cells throughout adulthood. However, contrary to the olfactory nerve which remained detectable in the adult, the optic nerve was only transiently expressed with NCAM-180 and was no longer detectable in the adult. The presence of NCAM-180 in olfactory tissues suggests their possible role in pathfinding, differentiation, fasciculation and synaptic plasticity. The continued presence of NCAM-180 in the olfactory system examined may underlie its continuous cell turnover and regenerative capacity. The continuous expression of NCAM-180 in ganglion cells, bipolar cells and photoreceptor cells, also suggests potential regenerating capability and some plastic functions for these cells in the adult. Since the expression of NCAM-180 by the optic nerve was restricted to the period of special histogenetic events, for example, during axonal growth and synaptogenesis, it is possible that the lack of NCAM-180 in the adult optic nerve might cause a nonpermissive environment for the regeneration and result in regenerative failure of this system.

• Asian-Australasian Journal of Animal Sciences
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• 제23권8호
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• pp.1000-1006
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• 2010

Phosducin (PDC) is a photoreceptor cell-specific protein that is phosphorylated by cyclic nucleotide-dependent protein kinase. PDC and PDC-like proteins (PDCL, PDCL2, and PDCL3) are members of a conserved family of small thioredoxin-like proteins that modulate the ${\beta}$- and ${\gamma}$-subunits of G-proteins. In mammals, Pdc, Pdcl, and Pdcl3 genes show ubiquitous expression; however, Pdcl2 gene expression is limited to the testis and ovary. The aim of the present study was to examine the expression patterns of chicken Pdcl2 (cPdcl2) during testicular and ovarian development. Protein sequence comparisons performed using the CLUSTAL X program revealed that the amino acid sequences and potential phosphorylation sites of cPDCL2 and mammalian PDCL2 proteins were highly conserved. Quantitative real-time PCR analysis revealed that cPdcl2 was differentially expressed in the testis and ovary. Specifically, cPdcl2 expression was detected at low levels in the ovary at all time points. In the testis, cPdcl2 expression was detected at low levels until 5 weeks of age. At 8 weeks of age, however, cPdcl2 showed increased expression levels in the testis. Using in situ hybridization, we detected high levels of cPdcl2 expression in the testis, particularly in the spermatocytes and round spermatids. In summary, our data describe expression patterns of germ cell-specific Pdcl2 during testicular and ovarian development in chickens.

• Applied Microscopy
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• 제29권2호
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• pp.231-239
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• 1999

초파리 단안의 발생단계에 따른 각막형성세포의 형태적인 변화를 관찰하고, 생산된 단백질의 이동방향을 조사하였다. 그 결과 우화 후 수일이 지나면서 각막형성세포는 그 기능이 급격하게 감소하는 것으로 보인다. 반면 우화 직후의 각막형성세포는 왕성한 분비활동을 하는 것으로 생각된다. 특히 자기방사섭의 결과에서는 각막형성세포에서 생산된 대부분의 단백질이 랜즈쪽으로 가는 것을 볼 때, 이 시기에서 이들 세포는 시세포에 기능하기보다는 렌즈형성에 주 기능을 할 것으로 사료된다. 번데기시기의 각막형성세포는 더욱 잘 발달되어 있었다. 렌즈가 형성되고 있는 시기의 각막형성세포에는 rER이 잘 발달되어 물질생산이 왕성하게 일어나고 있음을 보여주었다. 또한 분비과립과 미세소관이 많이 관찰되는데, 후자는 물질이 이동하는 통로를 제공하기 때문이다. 발생도중의 단안에서 새롭게 만들어진 렌즈의 가장 아래층의 저밀도의 불연속적 라멜라구조를 이루고 있고, 이 부분의 각막형성세포는 미세융모가 잘 발달되어 있어 물질을 분비하는 조직의 일반적인 특징을 보여준다. 결론적으로 각막형성세포는 렌즈가 왕성하게 형성되는 시기에는 잘 발달하고, 우화 후 완전히 형성된 추에는 그 기능이 급격하게 감소하면서 세포의 크기도 작아진 다는 것을 알 수 있었다.

• Journal of Photoscience
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• 제9권2호
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• pp.335-337
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• 2002

Blue light (BL) induces stomatal opening through activation of H$^{+}$ pump, which creates electrical gradient across the plasma membrane for $K^{+}$ uptake into guard cells. The pump is the plasma membrane H$^{+}$ -ATPase and is activated via phosphorylation of the C-terminus with concomitant binding of the 14-3-3 protein. The opening is initiated by the perception of BL through phototropin (phot), which are recently identified as BL receptors in stomatal guard cells. In this study, we provide the biochemical evidence for phots as BL receptors in stomatal guard cells. vfphot was phosphorylated reversibly by BL, and phosphorylation levels of vfphot increased earlier than those of the plasma membrane W-ATPase. BL-dependent phosphorylations of vfphot and H$^{+}$-ATPase showed similar fluence dependency. Staurosporin, an inhibitor of serine/threonine protein kinase, and diphenyleneiodonium chloride (DPI), an inhibitor of flavoprotein, inhibited BL-dependent phosphorylations of vfphot and H$^{+}$ -ATPase. These results indicate that vfphot acts as a BL-receptor mediating stomatal opening.l opening.

• Journal of Photoscience
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• 제7권3호
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• pp.123-128
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• 2000

Phosphorylation of cellular proteins is a key regulatory mehanism for signal transduction pathway in living cells. Phytochrome, a red/far-red light photoreceptor in plants, is known to employ protein phosphorylation for its light signaling, although its detauked mechanism is still ambiguous. This study is intended to identify the phosphoproteins and protein kinases that are regulated by phytochrome, by employing transgenic rice seedlings that overexpress Arabidopsis phytochrome A. Red light stimulated phsophorylation of a 70 kDa protein and far-red light negated the effect. The red light induced phosphotylation of the 70 kDa protein was strongly activated by heparin and inhibited by poly-L-lysine, suggesting that the 70 kDa protein phosphorylating kinase belongs to GSK-3/SHAGGY protein kinase that has functional roles in establishing cell fate and pattern formation in Drosophila. Taken together with the fact that phytochrome controls plant development, these results may suggest that a GSK-3/SHAGGY-related protein kinase in plant(ASK) is likely to be involved in phytochrome signal transduction.