The relationship between lens transmission and opsin gene expression in cichlids from Lake Malawi

Department of Biology, University of Maryland, College Park, MD 20742, United States.
Vision research (Impact Factor: 1.82). 12/2009; 50(3):357-63. DOI: 10.1016/j.visres.2009.12.004
Source: PubMed


The lens plays an important role in regulating the wavelengths of light that reach the retina. However, the evolutionary relationship between lens transmission and retinal sensitivity remains cloudy at best. We examined the relationship between lens transmission and opsin gene expression in a group of rapidly radiating cichlids from East Africa. Lens transmission was bimodal, either cutting off around 360 or 400 nm, and appeared to be quite labile evolutionarily. We found a strong correlation between lens transmission and SWS1 (UV) opsin gene expression, suggesting that UV transmitting lenses are adaptive in cichlids. Species which expressed high levels of SWS2B (violet) opsin varied in their lens transmission while most species that expressed high levels of SWS2A (blue) opsin had UV blocking lenses. In no instance did lens transmission appear to limit retinal sensitivity. Finally, the strong correlation that we observe between SWS1 expression and lens transmission suggests that these two traits might be coupled genetically.

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Available from: Karen Carleton, Oct 08, 2015
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    • "To correct the absorbance spectra of cone pigments for a non-UVtransmissive lens (T 50 =400nm), we used the lens transmission of another Lake Malawi cichlid, Melanochromis auratus (Hofmann et al., 2010). These T 50 values are commonly found in many freshwater and marine fishes (Siebeck and Marshall, 2007; Hofmann et al., 2010). For all analyses presented, unless specified differently, the visible spectrum and spectra of cone photoreceptors in fish were calculated while accounting for a UV-transmissive lens and photoreceptors of A 1 chromophore (case i), which are commonly found in many freshwater and marine fishes (Siebeck and Marshall, 2007; Toyama et al., 2008). "
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    • "Many fish species are able to sense wavelengths invisible for humans. Ultraviolet (UV) sensitivity was shown both in freshwater (Bowmaker, 1995) and marine fish (McFarland and Loew, 1994; Siebeck et al., 2010) of different orders such as Cypriniformes (Schiemenz, 1924; Muntz and Northmore, 1970; Hawryshyn and Beauchamp, 1985; Hawryshyn and Harosi, 1991; Risner et al., 2006), Salmoniformes (Bowmaker and Kunz, 1987; Anderson et al., 2010) and Perciformes (Carleton et al., 2000; Hofmann et al., 2010). UV sensitivity may be important for foraging behaviour as an adaptation to planktivory (Bowmaker and Kunz, 1987; McFarland and Loew, 1994; Bowmaker and Loew, 2008; Cronin, 2008), as well as for species discrimination and communication (Partridge and Cuthill, 2010; Siebeck et al., 2010). "
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