Androgens Increase lws Opsin Expression and Red Sensitivity in Male Three-Spined Sticklebacks

Abstract

Optomotor studies have shown that three-spined sticklebacks (Gasterosteus aculeatus) are more sensitive to red during summer than winter, which may be related to the need to detect the red breeding colour of males. This study aimed to determine whether this change of red light sensitivity is specifically related to reproductive physiology. The mRNA levels of opsin genes were examined in the retinae of sexually mature and immature fish, as well as in sham-operated males, castrated control males, or castrated males implanted with androgen 11-ketoandrostenedione (11 KA), maintained under stimulatory (L16:D8) or inhibitory (L8:D16) photoperiods. In both sexes, red-sensitive opsin gene (lws) mRNA levels were higher in sexually mature than in immature fish. Under L16:D8, lws mRNA levels were higher in intact than in castrated males, and were up-regulated by 11 KA treatment in castrated males. Moreover, electroretinogram data confirmed that sexual maturation resulted in higher relative red spectral sensitivity. Mature males under L16:D8 were more sensitive to red light than males under L8:D16. Red light sensitivity under L16:D8 was diminished by castration, but increased by 11 KA treatment. Thus, in sexually mature male sticklebacks, androgen is a key factor in enhancing sensitivity to red light via regulation of opsin gene expression. This is the first study to demonstrate that sex hormones can regulate spectral vision sensitivity.

Differentiation of visual spectra and nuptial colorations of two Paratanakia himantegus subspecies (Cyprinoidea: Acheilognathidae) in response to the distinct photic conditions of their habitats

“…Matsumoto et al (2014) suggested that speciation by sensory drive most likely occurs when the sensory trait is determined by a small number of loci. Indeed, the visual spectral sensitivity is related to the opsin genes, e.g., long-wavelength-sensitive opsin gene (lws) in cichlids, zebrafish (Danio rerio), and three-spined stickleback (Seehausen et al 2008;Shao et al 2014), or shortwavelength-sensitive opsin gene 2a (sws2a) in cichlids (Seehausen et al 2008). Moreover, body coloration is also likely to be determined by a limited number of genes.…”

“…Electroretinogram (ERG) recordings were mainly modified from Shao et al (2014). Fish were anesthetized with 0.025 % buffered MS-222 (ethyl 3-aminobenzoate, methanesulfonic acid salt), and then immobilized through an injection of gallamine triethiodide (Flaxedil; Sigma, St. Louis, MO, USA.…”

“…Immobilized fish were kept under dark conditions for at least 1.5 h for dark adaptation before the ERG recording. ERG tests were performed as described previously (Morita et al 1997;Seeliger et al 2002;Shao et al 2014). A 100-W halogen lamp (Osram 64637 100 W/12 V) in a lamp housing device (Nikon C-FI 115, Japan) was used as the light source for tests of visible spectra (400-670 nm).…”

South American Weakly Electric Fish (Gymnotiformes) Are Long-Wavelength-Sensitive Cone Monochromats

“…The second scan was executed in the same region to confirm that the visual pigment was bleached. All data were analyzed by a statistical program to obtain the λ max of the photoreceptor [Loew, 1994], which is an approach that was successfully used in our previous work [Wang et al, 2008[Wang et al, , 2009[Wang et al, , 2011Chang et al, 2009Chang et al, , 2015Shao et al, 2014]. Briefly, the absorbance curve was first normalized and then transformed from wavelength to frequency [MacNichol, 1986].…”

“…To remove variations between tests, values were normalized to a 0-100% scale, where 100% indicated the maximum sensitivity spectrum. This ERG method was applied in our earlier work on fish vision in the three-spined stickleback [Shao et al, 2014] and bitterlings . …”