The expression of three opsin genes from the compound eye of Helicoverpa armigera (Lepidoptera: Noctuidae) is regulated by a circadian clock, light conditions and nutritional status.

Shuo Yan,Xiaoxia Liu,Qingwen Zhang,Weilong Zhu,Xinfang Zhang,Jialin Zhu,Zhen Li,Nicholas S Foulkes

doi:10.1371/journal.pone.0111683

Shuo Yan, Xiaoxia Liu + Show 6 more

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https://doi.org/10.1371/journal.pone.0111683

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Abstract

Visual genes may become inactive in species that inhabit poor light environments, and the function and regulation of opsin components in nocturnal moths are interesting topics. In this study, we cloned the ultraviolet (UV), blue (BL) and long-wavelength-sensitive (LW) opsin genes from the compound eye of the cotton bollworm and then measured their mRNA levels using quantitative real-time PCR. The mRNA levels fluctuated over a daily cycle, which might be an adaptation of a nocturnal lifestyle, and were dependent on a circadian clock. Cycling of opsin mRNA levels was disturbed by constant light or constant darkness, and the UV opsin gene was up-regulated after light exposure. Furthermore, the opsin genes tended to be down-regulated upon starvation. Thus, this study illustrates that opsin gene expression is determined by multiple endogenous and exogenous factors and is adapted to the need for nocturnal vision, suggesting that color vision may play an important role in the sensory ecology of nocturnal moths.

Highlights

Vision is one of the most familiar forms of stimulus discrimination and plays numerous key roles in the performance of insect behaviors, such as searching for food and potential mates, avoiding predators and unsafe environments, and other specific behaviors [1,2,3,4,5]
We focused on selected genes encoding opsins in Helicoverpa armigera (Hubner) and investigated the determinants of opsin mRNA levels in a specific tissue, which was beneficial for improved understanding of the evolution and function of opsins in nocturnal moths
We presented a characterization of visual opsins in a nocturnal moth, the cotton bollworm H. armigera, which belongs to a markedly early branch within insect lineage

Summary

Introduction

Vision is one of the most familiar forms of stimulus discrimination and plays numerous key roles in the performance of insect behaviors, such as searching for food and potential mates, avoiding predators and unsafe environments, and other specific behaviors [1,2,3,4,5]. Compound eyes are usually composed of several thousand ommatidia to detect and convert light into visual images, and each ommatidium contains nine photoreceptor cells [6,7,8,9,10]. The visual pigments in photoreceptors include a vitamin A-derived chromophore, usually 11-cisretinal, and a transmembrane protein, opsin [11,12]. The amino acid sequences of both the opsin and the chromophore affect their ability to absorb visual pigment [12,13,14]. There are three types of opsins with peak absorbance at either the ultraviolet wavelengths (UV, 300–400 nm), blue wavelengths (BL, 400– 500 nm) or long wavelengths (LW, 500–600 nm) [8,10,12]

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