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Analysis of the opsin repertoire in the tardigrade Hypsibius dujardini provides insights into the evolution of opsin genes in panarthropoda.

Hering L, Mayer G - Genome Biol Evol (2014)

Bottom Line: Our opsin phylogeny further suggests that two r-opsins, including an "arthropsin," were present in the last common ancestor of Panarthropoda.Although both r-opsin lineages were retained in Onychophora and Arthropoda, the arthropsin was lost in Tardigrada.The single (most likely visual) r-opsin found in H. dujardini supports the hypothesis of monochromatic vision in the panarthropod ancestor, whereas two duplications of the ancestral panarthropod c-opsin have led to three c-opsins in tardigrades.

View Article: PubMed Central - PubMed

Affiliation: Animal Evolution and Development, Institute of Biology, University of Leipzig, Germany lars.hering@uni-leipzig.de.

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Visual organs in representatives of Panarthropoda. Although most onychophorans and tardigrades have a pair of simple, ocellus-like eyes (arrows in A and B), arthropods usually show two types of visual organs: The compound eyes (arrowheads in C) and the median ocelli (arrow in C). (A) Scanning electron micrograph of the head of the onychophoran Principapillatus hitoyensis in dorsal view. Scale bar: 1 mm. (B) Light micrograph of the head of the tardigrade Hypsibius dujardini in dorsal view. Scale bar: 10 µm. (C) Stereomicrograph of the head of the hymenopteran Ectemnius cavifrons in dorsal view. Scale bar: 1 mm.
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evu193-F1: Visual organs in representatives of Panarthropoda. Although most onychophorans and tardigrades have a pair of simple, ocellus-like eyes (arrows in A and B), arthropods usually show two types of visual organs: The compound eyes (arrowheads in C) and the median ocelli (arrow in C). (A) Scanning electron micrograph of the head of the onychophoran Principapillatus hitoyensis in dorsal view. Scale bar: 1 mm. (B) Light micrograph of the head of the tardigrade Hypsibius dujardini in dorsal view. Scale bar: 10 µm. (C) Stereomicrograph of the head of the hymenopteran Ectemnius cavifrons in dorsal view. Scale bar: 1 mm.

Mentions: Tardigrades typically possess a pair of simple, ocellus-like eyes (Kristensen 1983; Dewel et al. 1993; Greven 2007)—a situation which is similar to that in onychophorans but different from that in arthropods, which show two types of visual organs: The median ocelli and the compound eyes (fig. 1A–C). Although the onychophoran eyes have been homologized with the median ocelli of arthropods (Mayer 2006), the homology of the tardigrade eyes remains obscure (Greven 2007). Experimental data revealed that tardigrades clearly respond to light (Marcus 1929; Baumann 1961; Ramazzotti and Maucci 1983; Beasley 2001), but beyond this nothing is known about the photoreceptive system in these animals.Fig. 1.—


Analysis of the opsin repertoire in the tardigrade Hypsibius dujardini provides insights into the evolution of opsin genes in panarthropoda.

Hering L, Mayer G - Genome Biol Evol (2014)

Visual organs in representatives of Panarthropoda. Although most onychophorans and tardigrades have a pair of simple, ocellus-like eyes (arrows in A and B), arthropods usually show two types of visual organs: The compound eyes (arrowheads in C) and the median ocelli (arrow in C). (A) Scanning electron micrograph of the head of the onychophoran Principapillatus hitoyensis in dorsal view. Scale bar: 1 mm. (B) Light micrograph of the head of the tardigrade Hypsibius dujardini in dorsal view. Scale bar: 10 µm. (C) Stereomicrograph of the head of the hymenopteran Ectemnius cavifrons in dorsal view. Scale bar: 1 mm.
© Copyright Policy - creative-commons
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC4202329&req=5

evu193-F1: Visual organs in representatives of Panarthropoda. Although most onychophorans and tardigrades have a pair of simple, ocellus-like eyes (arrows in A and B), arthropods usually show two types of visual organs: The compound eyes (arrowheads in C) and the median ocelli (arrow in C). (A) Scanning electron micrograph of the head of the onychophoran Principapillatus hitoyensis in dorsal view. Scale bar: 1 mm. (B) Light micrograph of the head of the tardigrade Hypsibius dujardini in dorsal view. Scale bar: 10 µm. (C) Stereomicrograph of the head of the hymenopteran Ectemnius cavifrons in dorsal view. Scale bar: 1 mm.
Mentions: Tardigrades typically possess a pair of simple, ocellus-like eyes (Kristensen 1983; Dewel et al. 1993; Greven 2007)—a situation which is similar to that in onychophorans but different from that in arthropods, which show two types of visual organs: The median ocelli and the compound eyes (fig. 1A–C). Although the onychophoran eyes have been homologized with the median ocelli of arthropods (Mayer 2006), the homology of the tardigrade eyes remains obscure (Greven 2007). Experimental data revealed that tardigrades clearly respond to light (Marcus 1929; Baumann 1961; Ramazzotti and Maucci 1983; Beasley 2001), but beyond this nothing is known about the photoreceptive system in these animals.Fig. 1.—

Bottom Line: Our opsin phylogeny further suggests that two r-opsins, including an "arthropsin," were present in the last common ancestor of Panarthropoda.Although both r-opsin lineages were retained in Onychophora and Arthropoda, the arthropsin was lost in Tardigrada.The single (most likely visual) r-opsin found in H. dujardini supports the hypothesis of monochromatic vision in the panarthropod ancestor, whereas two duplications of the ancestral panarthropod c-opsin have led to three c-opsins in tardigrades.

View Article: PubMed Central - PubMed

Affiliation: Animal Evolution and Development, Institute of Biology, University of Leipzig, Germany lars.hering@uni-leipzig.de.

Show MeSH
Related in: MedlinePlus