Light-/dark-induced changes in rhabdom structure in the retina of Octopus bimaculoides

Torres, Steven C.; Camacho, Jose L.; Matsumoto, Brian; Kuramoto, Richard T.; Robles, Laura J.

doi:10.1007/s004410050918

Cited by 10 publications

(18 citation statements)

References 44 publications

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“…The membrane of each rhabdomere microvillus contains rhodopsin and signal transduction proteins necessary to process the visual signal after light absorption by rhodopsin as well as a core of actin filaments and accessory proteins (Robles et al 1995, De Velasco et al 1999). As mentioned, the rhabdoms increase in size in the dark, by the addition and lengthening of the rhabdomere microvilli, and decrease in the light by the disassembly and shortening of the same microvilli (Torres et al 1997). …”

Section: Resultsmentioning

confidence: 97%

“…Rhabdom cross-sectional areas increase in size in the dark and diminish in the light (Torres et al 1997). This increase can be explained by either the addition of new microvilli or increase in size of microvilli already present.…”

Section: Discussionmentioning

confidence: 99%

“…In Octopus bimaculoides (Pickford and McConnaughey, 1949), distinct changes in photoreceptor shape occur in the light and dark and may be directly attributable to changes in the organization of the cytoskeleton. Torres et al (1997) compared the relative cross-sectional area of light- and dark-adapted rhabdoms, the light sensitive region of the cell, and outer segment core cytoplasm and found that the rhabdoms of light-adapted photoreceptors are reduced in cross-sectional area when compared to those maintained in the dark. Electron microscopy showed that the rhabdomeric microvilli in light-adapted rhabdoms partially disappeared, leaving behind an avillar membrane connecting the microvilli on opposite sides of the rhabdoms.…”

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confidence: 99%

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Rho Signaling Mediates Cytoskeletal Re-arrangements in Octopus Photoreceptors*

Gray¹,

Kelly²,

Robles³

2008

American Malacological Bulletin

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Light sensitive rhabdoms in the octopus retina increase in cross-sectional area in the dark and shrink in the light. Growth in the dark is due to the formation of microvilli in an avillar region of the photoreceptor cell membrane and lengthening of rhabdomere microvilli already present. Diminution in the light is the result of the disassembly and shortening of the same microvilli. Each microvillus contains an actin filament core that must be assembled or disassembled in the dark or light, respectively. To understand the regulation of the construction and breakdown of rhabdomere microvilli in the light and dark, we used centrifugation to separate the rhabdom membranes followed by Western blotting and Rho pull-down assays to investigate the role of Rho GTPases in this process. Western blotting showed a difference in the distribution of Rho in rhabdom membrane and supernatant fractions. In the light, Rho was mostly present in the supernatant but in the dark it was found in the fraction enriched with rhabdom membranes. Complementing these results, pull-down assays showed that Rho is activated in the dark but in the light, Rho is mostly inactive. We believe that in the dark, activated Rho binds to the rhabdom membrane and initiates signaling pathways, leading to growth of rhabdomere microvilli. In the light, Rho is present in the soluble fraction, is inactivated, and is likely bound to a Rho GDI. Receptors involved in the activation of Rho in the dark are undetermined and may involve rhodopsin or another membrane protein.

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Section: Resultsmentioning

confidence: 97%

Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

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Rho Signaling Mediates Cytoskeletal Re-arrangements in Octopus Photoreceptors*

Gray¹,

Kelly²,

Robles³

2008

American Malacological Bulletin

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“…Contraction and elongation of cone cells in fish eyes are regulated by actin and microtubles, respectively[16]. Rhabdom size of octopus[15] and some terrestrial isopods, fly, and crayfish are also controlled by actin filaments[13,14,27]. The morphological change of the ocelloid of Erythropsidinium in response to light resembles the alteration in size of rhabdomere cells of some cephalopods and arthropods.…”

Section: Discussionmentioning

confidence: 99%

Function and Evolutionary Origin of Unicellular Camera-Type Eye Structure

et al. 2015

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The ocelloid is an extraordinary eyespot organelle found only in the dinoflagellate family Warnowiaceae. It contains retina- and lens-like structures called the retinal body and the hyalosome. The ocelloid has been an evolutionary enigma because of its remarkable resemblance to the multicellular camera-type eye. To determine if the ocelloid is functionally photoreceptive, we investigated the warnowiid dinoflagellate Erythropsidinium. Here, we show that the morphology of the retinal body changed depending on different illumination conditions and the hyalosome manifests the refractile nature. Identifying a rhodopsin gene fragment in Erythropsidinium ESTs that is expressed in the retinal body by in situ hybridization, we also show that ocelloids are actually light sensitive photoreceptors. The rhodopsin gene identified is most closely related to bacterial rhodopsins. Taken together, we suggest that the ocelloid is an intracellular camera-type eye, which might be originated from endosymbiotic origin.

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“…This is surprising, as molluscan systems have shown potential for study of basic visual processes, physiology of vision, development of the visual system, and evolution. For example, past work (Robles et al 1995, Torres et al 1997 has shown that cytoskeletal organization of photoreceptor cells is regulated by the state of light-and dark-adaptation in cephalopod eyes. It is known that some disease states in the human retina, such as macular degeneration, affect cytoskeletal development and organization (Eckmiller 2004).…”

Section: Molluscs As "Non-traditional" Model Organisms For Studying Tmentioning

confidence: 99%

Toward Developing Models to Study the Disease, Ecology, and Evolution of the Eye in Mollusca*

Serb

2008

American Malacological Bulletin

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Several invertebrate systems have been developed to study various aspects of the eye and eye disease including Drosophila, Planaria, Platynereis, and most recently, the cubozoan jellyfish Tripedalia; however, molluscs, the second largest metazoan phylum, so far have been underrepresented in eye research. This is surprising as mollusc systems offer opportunities to study visual processes that may be altered by disease, vision physiology, development of the visual system, behavior, and evolution. Malacologists have labored for over a century as morphologists, systematists, physiologists, and ecologists in order to understand the structural and functional diversity in molluscs at all levels of biological organization. Yet, malacologists have had little opportunity to interact with researchers whose interests are restricted to the biology and development of eyes as model systems as they tend not to publish in the same journals or attend the same meetings. In an effort to highlight the advantages of molluscan eyes as a model system and encourage greater collaboration among researchers, I provide an overview of molluscan eye research from these two perspectives: eye researchers whose interests involve the development, physiology, and disease of the eye and malacologists who study the complete organism in its natural environment. I discuss the developmental and genetic information available for molluscan eyes and the need to place this work in an evolutionary perspective. Finally, I discuss how synergy between these two groups will advance eye research, broaden research in both fields, and aid in developing new molluscan models for eye research. Abstract: Several invertebrate systems have been developed to study various aspects of the eye and eye disease including Drosophila, Planaria, Platynereis, and most recently, the cubozoan jellyfish Tripedalia; however, molluscs, the second largest metazoan phylum, so far have been underrepresented in eye research. This is surprising as mollusc systems offer opportunities to study visual processes that may be altered by disease, vision physiology, development of the visual system, behavior, and evolution. Malacologists have labored for over a century as morphologists, systematists, physiologists, and ecologists in order to understand the structural and functional diversity in molluscs at all levels of biological organization. Yet, malacologists have had little opportunity to interact with researchers whose interests are restricted to the biology and development of eyes as model systems as they tend not to publish in the same journals or attend the same meetings. In an effort to highlight the advantages of molluscan eyes as a model system and encourage greater collaboration among researchers, I provide an overview of molluscan eye research from these two perspectives: eye researchers whose interests involve the development, physiology, and disease of the eye and malacologists who study the complete organism in its natural environment. I discuss the developmental and genet...

show abstract

Light-/dark-induced changes in rhabdom structure in the retina of Octopus bimaculoides

Cited by 10 publications

References 44 publications

Rho Signaling Mediates Cytoskeletal Re-arrangements in Octopus Photoreceptors*

Rho Signaling Mediates Cytoskeletal Re-arrangements in Octopus Photoreceptors*

Function and Evolutionary Origin of Unicellular Camera-Type Eye Structure

Toward Developing Models to Study the Disease, Ecology, and Evolution of the Eye in Mollusca*

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