A simple visual system without neurons in jellyfish larvae

Nordström, Karin; Wallén, Rita; Seymour, Jamie; Nilsson, Dan-Eric

doi:10.1098/rspb.2003.2504

Cited by 98 publications

(78 citation statements)

References 23 publications

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“…Our results also predict that rhabdomeric receptors should exist in Cnidaria. This has not yet been proven, but cells with a strong resemblance to the bilaterian rhabdomeric receptors, which could be cnidarian rhabdomeric receptors, have been observed in cnidarian larvae (9,24,33).…”

Section: Discussionmentioning

confidence: 99%

Metazoan opsin evolution reveals a simple route to animal vision

Feuda

Hamilton

McInerney

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

170

212

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The authors wish to note the following: "The contrast of our final projection map was inverted, so that we interpreted the background density rather than the actual protein density in terms of structural features of the potassium channel-Fv complex. In addition, we indexed the 2D crystals with unit cell parameters of a = b = 175 Å, while the correct indexing would be a = b = 124 Å. Given these analysis errors, the resulting density map and our interpretation of the structural features are not correct. Accordingly, we would like to retract this paper. We acknowledge Yoshinori Fujiyoshi, Rod MacKinnon, Kazutoshi Tani, and Tom Walz for identifying the errors and pointing them out to us."

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Section: Discussionmentioning

confidence: 99%

Metazoan opsin evolution reveals a simple route to animal vision

Feuda

Hamilton

McInerney

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

170

212

View full text Add to dashboard Cite

show abstract

“…It can be found, among others, in the green alga Chlamydomonas [26], the excavate Euglena, the cryptophyte alga Cryptomonas [25], or in the ciliated spores of the chytrid fungi Allomyces [34]. An analogous spiral swimming phototactic strategy is found in the multicellular green alga Volvox [35], and also in the ciliated larvae of animals including sponges [36,37], cnidarians [38,39], annelids [8] and molluscs [40]. Some animal larvae, such as sponges [36,37] and some cnidarians [38], perform phototaxis without a nervous system, while others, including some cnidarians [39] and many bilaterians [8,40], perform phototaxis with a nervous system.…”

Section: The Efficiency Of Sensory-to-motor Transformation With and Wmentioning

confidence: 99%

“…An analogous spiral swimming phototactic strategy is found in the multicellular green alga Volvox [35], and also in the ciliated larvae of animals including sponges [36,37], cnidarians [38,39], annelids [8] and molluscs [40]. Some animal larvae, such as sponges [36,37] and some cnidarians [38], perform phototaxis without a nervous system, while others, including some cnidarians [39] and many bilaterians [8,40], perform phototaxis with a nervous system. Phototaxis therefore provides a very useful paradigm to assess the benefits of nervous systems in a comparative framework, even if we are comparing independent evolutionary innovations [33].…”

Section: The Efficiency Of Sensory-to-motor Transformation With and Wmentioning

confidence: 99%

Origin and early evolution of neural circuits for the control of ciliary locomotion

Jékely

2010

Proc. R. Soc. B.

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Behaviour evolved before nervous systems. Various single-celled eukaryotes (protists) and the ciliated larvae of sponges devoid of neurons can display sophisticated behaviours, including phototaxis, gravitaxis or chemotaxis. In single-celled eukaryotes, sensory inputs directly influence the motor behaviour of the cell. In swimming sponge larvae, sensory cells influence the activity of cilia on the same cell, thereby steering the multicellular larva. In these organisms, the efficiency of sensory-to-motor transformation (defined as the ratio of sensory cells to total cell number) is low. With the advent of neurons, signal amplification and fast, long-range communication between sensory and motor cells became possible. This may have first occurred in a ciliated swimming stage of the first eumetazoans. The first axons may have had en passant synaptic contacts to several ciliated cells to improve the efficiency of sensory-to-motor transformation, thereby allowing a reduction in the number of sensory cells tuned for the same input. This could have allowed the diversification of sensory modalities and of the behavioural repertoire. I propose that the first nervous systems consisted of combined sensory-motor neurons, directly translating sensory input into motor output on locomotor ciliated cells and steering muscle cells. Neuronal circuitry with low levels of integration has been retained in cnidarians and in the ciliated larvae of some marine invertebrates. This parallel processing stage could have been the starting point for the evolution of more integrated circuits performing the first complex computations such as persistence or coincidence detection. The sensory-motor nervous systems of cnidarians and ciliated larvae of diverse phyla show that brains, like all biological structures, are not irreducibly complex.

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“…For example, certain butterflies have light detecting organs located such that darkness signals successful copulation (Arikawa et al, 1996). And recently Nilsson and colleagues (Nordström et al, 2003), described a visual system in the planula of a box jellyfish Tripedalia cystophora with eyecups directly connected to motor cilium. That is, no nervous system to process information because the eyes are a complete sensory-motor system unto themselves.…”

Section: Eye Varietymentioning

confidence: 99%

“…It would be unsurprising, for example, to find them in the recently described eye without a nervous system (Nordström et al, 2003). Then as different eye types evolved, there was probably repeated recruitment of particular gene groups, not unlike improvisational groups of actors, interacting to produce candidates for selection.…”

Section: How Did Eyes Evolve: Independently Recruited Genes?mentioning

confidence: 99%

Evolving eyes

Fernald¹

2004

Int. J. Dev. Biol.

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Despite the incredible diversity among extant eyes, laws of physics constrain how light can be collected resulting in only eight known optical systems in animal eyes. Surprisingly, all animal eyes share a common molecular strategy using opsin for catching photons, but there are a diverse collection of mechanisms with proteins unrelated to each other used to focus light for vision. However, opsin is expressed in either one of two types of photoreceptor that differ fundamentally in their structure and tissue of origin. Taken together, this collection of observations strongly suggests that eyes have had multiple origins with remarkable convergence due to physics and molecular conservation of the opsin protein. Yet recent work has shown that a family of conserved genes are involved in eye formation despite substantial differences in their structure and origin, leading to a controversy over whether eyes evolved once or repeatedly. A likely resolution of this discussion is that particular genes and genetic programs have become associated with specific features needed for eyes and such suites of genes have been recruited as new eyes evolve. Since specific genes and their products are used repeatedly, it is somewhat difficult to conceptualize their causal relationships relative to evolutionary processes. However, detailed comparison of developmental programs may offer clues about multiple origins.

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A simple visual system without neurons in jellyfish larvae

Cited by 98 publications

References 23 publications

Metazoan opsin evolution reveals a simple route to animal vision

Metazoan opsin evolution reveals a simple route to animal vision

Origin and early evolution of neural circuits for the control of ciliary locomotion

Evolving eyes

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