LOSS OF BOTH SHORT WAVELENGTH CONE OPSIN GENES IN REPRESENTATIVES OF THE NOCTURNALLY-ACTIVE GYMNOTIFORM WEAKLY ELECTRIC FISHES AND THEIR SISTER GROUP, THE CATFISHES.
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1
The University of Texas, Section of Neurobiology, United States
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2
University of Wisconsin, Dept. of Biochemistry, United States
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3
Systemix Institute, United States
Teleosts typically possess genes for the rod photopigment rhodopsin, and at least four cone photopigments: a long wavelength-sensitive (LWS), a medium wavelength-sensitive (MWS), and two short wavelength-sensitive (SWS) opsins. We interrogated the newly sequenced (100x coverage) genome of the South American gymnotiform the electric eel (Electrophorus electricus) and observed rhodopsin, LWS, and MWS opsin genes but neither of the two SWS opsin genes. Because catfish are the sister group of gymnotiforms, we then interrogated EST databases from two catfishes (Ictalurus sp.) and observed the same pattern. Catfishes and gymnotiforms are both nocturnally-active groups. Our data suggest that SWS opsins were either lost in a common ancestor of both groups or, alternatively, lost independently in both groups. We are currently sampling opsins from the retinas of more species of catfishes and gymnotiforms to answer this question. Catfishes and gymnotiforms often live in muddy rivers and streams where the ambient light is strong in the long wavelengths. Thus, the loss of SWS pigments is likely adaptive as it allows a greater number of photoreceptors with photopigments in the most useful portions of the visual spectrum. We are also sampling retinal opsins in the other independently evolved group of weakly electric teleosts, the mormyriformes and their closest non-electric relatives to determine if SWS opsins are lost convergently in mormyriformes. The loss of SWS opsins has been reported in mammals that live in dim light conditions or utilize other specialized sensory systems to obtain information such as bats and cetaceans. The loss of SWS cone opsins in animals that inhabit low light environments is a recurring evolutionary theme.
Keywords:
catFISH,
Electric Fish,
Genes,
molecular evolution,
Opsins
Conference:
Tenth International Congress of Neuroethology, College Park. Maryland USA, United States, 5 Aug - 10 Aug, 2012.
Presentation Type:
Poster Presentation (see alternatives below as well)
Topic:
Evolution
Citation:
Zakon
H,
Sussman
M,
Traeger
L and
Samanta
M
(2012). LOSS OF BOTH SHORT WAVELENGTH CONE OPSIN GENES IN REPRESENTATIVES OF THE NOCTURNALLY-ACTIVE GYMNOTIFORM WEAKLY ELECTRIC FISHES AND THEIR SISTER GROUP, THE CATFISHES..
Conference Abstract:
Tenth International Congress of Neuroethology.
doi: 10.3389/conf.fnbeh.2012.27.00098
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Received:
24 Apr 2012;
Published Online:
07 Jul 2012.
*
Correspondence:
Dr. Harold Zakon, The University of Texas, Section of Neurobiology, Austin, Texas, 78712, United States, h.zakon@mail.utexas.edu