Sexual dimorphic photoreceptor organization of the retina of Eastern Clouded Yellow butterfly, Colias erate
-
1
Sokendai-Hayama, Department of Evolutionary Studies of Biosystems, Japan
-
2
University of Groningen, Department of Neurobiophysics, Netherlands
The compound eye of Colias erate is composed of about 6,500 ommatidia. Each ommatidium contains nine photoreceptors (R1-9) forming a tiered rhabdom. Four reddish pigment clusters surround the rhabdom. The ommatidia are divided into three types (I-III) according to the arrangement of pigment and the expression pattern of four mRNAs encoding opsins of the visual pigments: CeUV, CeV1, CeV2 and CeL. By in situ hybridization we discovered in R1/2 of type II ommatidia in the ventral region of the eye another mRNA encoding the opsin of a blue-absorbing visual pigment, CeB. Because it is found always together with CeV1 and CeV2, these receptors express three opsins.
To elucidate how the multiple opsins function in single cells, we measured the spectral sensitivity of all photoreceptor classes of the ventral retina of C. erate by electrophysiological recordings, and we developed an optical model that reproduced the photoreceptor spectra. We identified 4 classes of spectral receptors (UV, B, G, R). The B receptor class, which is made up of R1 and/or R2 receptors of type I and II ommatidia, is sexually dimorphic. Based on the shape of the sensitivity spectra, we sub-divided the spectral classes into shouldered-blue (sB), violet (V), broad-blue (bB) and narrow-blue (nB). In type I, males have sB (peaking at 440 with a low sensitivity at 420nm), while females have V receptors expressing CeV1 and CeV2. In type II, males have bB (sensitive in the range of 420-480 nm), while females have nB (peaking at 460 nm with a low sensitivity at 400 nm) expressing CeV1, CeV2 and CeB. The sensitivity spectrum of the bB cells was well modeled by postulating that three visual pigments contributed: peaking at 430 nm (CeV1, CeV2) and 460 nm (CeB), respectively. The sexual dimorphism (bB vs nB) was attributable to the sex-specific localization of fluorescing pigment, which acts as a violet-absorbing spectral filter in type I in males and type II in females.
Sexual dimorphism was also encountered in R receptors localized in the proximal tier of the retina (R5-8). Those in type II peak at 620 nm in females and at 660 nm in males. The R receptors share a visual pigment (CeL) with green receptors whose sensitivity peaks at 565 nm. The red-shift of the spectral sensitivity of the R5-8 is due to the perirhabdormal pigments, which act as optical long-pass filters. The male retina has only red pigments, but the female has also an orange pigment, in type II ommatidia. The sexual dimorphism was found only in the ventral retina. This implies that any visual function related to sexual behaviors is restricted to the ventral eye region.
Keywords:
Color Vision,
Opsin,
photoreceptor,
sexual dimorphism
Conference:
Tenth International Congress of Neuroethology, College Park. Maryland USA, United States, 5 Aug - 10 Aug, 2012.
Presentation Type:
Poster (but consider for student poster award)
Topic:
Sensory: Vision
Citation:
Ogawa
Y,
Awata
H,
Kinoshita
M,
Stavenga
DG and
Arikawa
K
(2012). Sexual dimorphic photoreceptor organization of the retina of Eastern Clouded Yellow butterfly, Colias erate.
Conference Abstract:
Tenth International Congress of Neuroethology.
doi: 10.3389/conf.fnbeh.2012.27.00102
Copyright:
The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers.
They are made available through the Frontiers publishing platform as a service to conference organizers and presenters.
The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated.
Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed.
For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions.
Received:
24 Apr 2012;
Published Online:
07 Jul 2012.
*
Correspondence:
Ms. Yuri Ogawa, Sokendai-Hayama, Department of Evolutionary Studies of Biosystems, Hayama, 240-0193, Japan, yuriogawa.kato@mq.edu.au