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Title: Rapid light-induced shifts in opsin expression: finding new opsins, discerning mechanisms of change, and implications for visual sensitivity: RAPID LIGHT-INDUCED SHIFTS IN OPSIN EXPRESSION
Award ID(s):
Publication Date:
Journal Name:
Molecular Ecology
Page Range or eLocation-ID:
3321 to 3335
Sponsoring Org:
National Science Foundation
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  1. Stomatopod crustaceans possess some of the most complex animal visual systems, including at least 16 spectrally distinct types of photoreceptive units (e.g., assemblages of photoreceptor cells). Here we fully characterize the set of opsin genes expressed in retinal tissues and determine expression patterns of each in the stomatopodNeogonodactylus oerstedii. Using a combination of transcriptome and RACE sequencing, we identified 33 opsin transcripts expressed in eachN. oerstediieye, which are predicted to form 20 long-wavelength–sensitive, 10 middle-wavelength–sensitive, and three UV-sensitive visual pigments. Observed expression patterns of these 33 transcripts were highly unusual in five respects: 1) All long-wavelength and short/middle-wavelength photoreceptive unitsmore »expressed multiple opsins, while UV photoreceptor cells expressed single opsins; 2) most of the long-wavelength photoreceptive units expressed at least one middle-wavelength–sensitive opsin transcript; 3) the photoreceptors involved in spatial, motion, and polarization vision expressed more transcripts than those involved in color vision; 4) there is a unique opsin transcript that is expressed in all eight of the photoreceptive units devoted to color vision; and 5) expression patterns in the peripheral hemispheres of the eyes suggest visual specializations not previously recognized in stomatopods. Elucidating the expression patterns of all opsin transcripts expressed in theN. oerstediiretina reveals the potential for previously undocumented functional diversity in the already complex stomatopod eye and is a first step toward understanding the functional significance of the unusual abundance of opsins found in many arthropod species’ visual systems.

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  2. Synopsis

    Animals use visual communication to convey crucial information about their identity, reproductive status, and sex. Plasticity in the auditory and olfactory systems has been well-documented, however, fewer studies have tested for plasticity in the visual system, a surprising detail since courtship and mate choice are largely dependent on visual signals across taxa. We previously found reproductive state-dependent plasticity in the eye of the highly social cichlid fish Astatotilapia burtoni. Male A. burtoni increase their courtship, including multicomponent visual displays, when around ovulated females, and ovulated females are more responsive to male visual courtship displays than non-ovulated females. Based onmore »this, we hypothesized that ovulation status impacts visual capabilities in A. burtoni females. Using electroretinograms, we found that ovulated females had greater visual sensitivity at wavelengths corresponding to male courtship coloration compared with non-reproductively-receptive females. In addition, ovulated females had higher neural activation in the retina and higher mRNA expression levels of neuromodulatory receptors (e.g., sex-steroids; gonadotropins) in the eye than non-ovulated females. Here, we add to this body of work by testing the hypothesis that cone opsin expression changes with female reproductive state. Ovulated females had higher expression of short wavelength sensitive opsins (sws1, sws2a, sws2b) compared with mouthbrooding females. Further, expression of sws2a, the most abundant opsin in the A. burtoni eye, positively correlated with levels of circulating 11-ketotestosterone and estradiol and estrogen, androgen, and gonadotropin system receptor expression in the eye in females. These data indicate that reproductive state-dependent plasticity also occurs at the level of photoreceptors, not just through modulation of visual signals at downstream retinal layers. Collectively, these data provide crucial evidence linking endocrine modulation of visual plasticity to mate choice behaviors in females.

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