The evolution of early vertebrate photoreceptors

Abstract

Meeting the challenge of sampling an ancient aquatic landscape by the early vertebrates was crucial to their survival and would establish a retinal bauplan to be used by all subsequent vertebrate descendents. Image-forming eyes were under tremendous selection pressure and the ability to identify suitable prey and detect potential predators was thought to be one of the major drivers of speciation in the Early Cambrian. Based on the fossil record, we know that hagfishes, lampreys, holocephalans, elasmobranchs and lungfishes occupy critical stages in vertebrate evolution, having remained relatively unchanged over hundreds of millions of years. Now using extant representatives of these 'living fossils', we are able to piece together the evolution of vertebrate photoreception. While photoreception in hagfishes appears to be based on light detection and controlling circadian rhythms, rather than image formation, the photoreceptors of lampreys fall into five distinct classes and represent a critical stage in the dichotomy of rods and cones. At least four types of retinal cones sample the visual environment in lampreys mediating photopic (and potentially colour) vision, a sampling strategy retained by lungfishes, some modern teleosts, reptiles and birds. Trichromacy is retained in cartilaginous fishes (at least in batoids and holocephalans), where it is predicted that true scotopic (dim light) vision evolved in the common ancestor of all living gnathostomes. The capacity to discriminate colour and balance the tradeoff between resolution and sensitivity in the early vertebrates was an important driver of eye evolution, where many of the ocular features evolved were retained as vertebrates progressed on to land.

Photoreception and vision in the ultraviolet

“…2C) (Shi and Yokoyama, 2003;Henze and Oakley, 2015). Among vertebrates, SWS1 opsin is present in all major extant groups except elasmobranchs, including early-branching lampreys, where it forms a UV visual pigment (Collin et al, 2003(Collin et al, , 2009. In teleosts and lungfish, SWS1 seems to form only UV visual pigments (Bailes et al, 2007;Hart et al, 2008); the single known exception is the deepsea scabbardfish, in which the position 86 tuning site is deleted, resulting in a violet visual pigment (Tada et al, 2009) (Fig.…”

RNA-Seq Transcriptome Analysis of the Cutlass Fish Reveals Photoreceptors Gene Expression in Peripheral Tissues

“…또한 조 류에서는 뇌에 존재하는 pinopsin, VA-opsin (Soni and Foster 1997)과 어류에서는 제브라피쉬, D. rerio에서 송과 체에 존재하는 exo-rodopsin이 체색변화나 번식생리에 직 접적으로 영향을 미친다는 연구결과들이 보고되었다 (Collin et al 2009 갈치 광수용체 아미노산 구조 갈치 광수용체의 아미노산 염기서열과 다른 척추동물들 과의 상동성은 RRH(어류 72−90%, 조류 77%, 그리고 포 유류 62−68%), Opn4(어류 33−80% 그리고 조류 36%), Rh1(어류 83−89%, 조류 76% 그리고 포유류 72%), Rh2 (어류 78−87%, 조류 68% 그리고 포유류 36−41%), VAopsin(어류 72−90%, 조류 63%), Opn3(어류 77−90%, 조 류 64%, 포유류 56−59%) 아미노산 염기서열 모두 어류 와 비교적 높은 상동성을 보였다 (Fig. 1, Table 3).…”

“…2). 이러한 결과는 다른 어류나 포유 류에서 보고된 광수용체 유전자 및 아미노산 서열과 유사 하며 구조적으로도 일치한다고 사료된다 (Terakita 2005;Collin et al 2009). …”

Wildlife Deterrence from Hazards Using High Brightness Ultraviolet Light

“…It is believed that specie *Corresponding author: Donald J. Ronning, B. S. chemistry, B. S. photographic science, research field: avian vision and behavior. evolution and adaptation has driven gene-sequence variation within each of the photo pigments families which can be tuned to absorb preferentially across a restricted range of the spectrum [2]. Two variants of ultraviolet color vision have been identified in birds with a pronounced difference in the wavelength of peak absorbance of the SWS1 cone.…”