Vision adaptation in the laughing dove (Streptopelia senegalensis, Linnaeus, 1766) inferred from structural, ultrastructural, and genetic characterization

• Published in: Journal of comparative neurology (1911) Vol. 529; no. 8; pp. 1830 - 1848
• Main Authors: Sultan, Aya E., Ghoneim, Ahmed M., El‐Gammal, Hekmat L., El‐Bakary, Neveen E. R.
• Format: Journal Article
• Language: English
• Published: Hoboken, USA John Wiley & Sons, Inc 01.06.2021; Wiley Subscription Services, Inc
• Subjects: Acclimation; Acuity; Adaptation; Adaptation, Physiological - physiology; Anatomy; Animals; Color vision; Columbidae - anatomy & histology; Columbidae - physiology; Epithelium; Female; laughing dove (Streptopelia senegalensis); Long-wavelength opsin; Male; Melanosomes; Mueller cells; Myelination; Neuronal Plasticity - physiology; Oligodendrocytes; Opsins; Photons; photoreceptors; Phylogeny; Regeneration; Retina; Retina - physiology; Retina - ultrastructure; Retinal pigment epithelium; shortwave‐sensitive opsin 1 (SWS1); Streptopelia senegalensis; vision; Visual Perception - physiology; photoreceptors; vision; phylogeny; shortwave-sensitive opsin 1 (SWS1); laughing dove (Streptopelia senegalensis); retina
• ISSN: 0021-9967; 1096-9861
• DOI: 10.1002/cne.25059

Neuroanatomy of the retina reflects adaptation and acclimation for dark and light conditions. Retinal cells and genes must be functionally adjusted to various environmental luminosities. Opsins are brilliant molecules to assess the adaptations at the genetic and phenotypic levels. Photic adaptations may reveal new mechanisms that enhance vision abilities. Through the investigation of histological, ultrastructural constituents of the whole retinal layers, and the sequencing of shortwave length sensitive opsin 1 (SWS1) of the laughing dove (Streptopelia senegalensis), the current study confirms the plasticity of the retina in response to the natural photic conditions. Retinal pigmented epithelium has plentiful melanosomes, signifying a highly adapted eye for maximum light perception and protection. Variously colored oil droplets signify high color vision ability. Stratified outer nuclear layer with many Müller cells suggests high sensitivity to dim conditions and high retinal regeneration. The penetration of outer limiting membrane by photoreceptor nuclei and Müller cell microvilli could minimize the light reflection. Oligodendrocytes establish thick myelination demanded for a keen visual acuity. A functional violet sensitive SWS1 with crucial Ser90 is presumed. Molecular phylogeny showed a secondary loss as color vision was shifted back from ultraviolet (UV) sensitivity to the ancestral avian violet sensitivity, thus improving visual resolution. However, SWS1 has some UV sensitive residues. These findings implicate not only spectral adaptations with high color vision ability and acuity but also photoinduced structural reorganizations. Further studies are needed to assess the secrets between photons and the structural genes. We characterized the under‐explored retina of the laughing dove, Streptopelia senegalensis. In addition to light and electron microscopy, we sequenced the short wavelength sensitive opsin SWS1. Using phylogeny and multiple sequence alignment, we found that the SWS1 is a violet sensitive opsin. Our results showed the presence of retinal pigmented epithelium that has plentiful melanosomes. There were various oil droplets, cones, horizontal, amacrine, bipolar, and Müller cells. Oligodendrocytes myelinated the nerve fiber layer. Overall, our data suggest a link between the structural variation and the photic adaptation.