TY - JOUR

T1 - Expression of Opsins of the Box Jellyfish Tripedalia cystophora Reveals the First Photopigment in Cnidarian Ocelli and Supports the Presence of Photoisomerases

AU - Garm, Anders

AU - Svaerke, Jens-Erik

AU - Pontieri, Daniela

AU - Oakley, Todd H.

N1 - Publisher Copyright: Copyright © 2022 Garm, Svaerke, Pontieri and Oakley.

PY - 2022

Y1 - 2022

N2 - Cubomedusae, or box jellyfish, have a complex visual system comprising 24 eyes of four types. Like other cnidarians, their photoreceptor cells are ciliary in morphology, and a range of different techniques together show that at least two of the eye types—the image-forming upper and lower lens eyes—express opsin as the photopigment. The photoreceptors of these two eye types express the same opsin (Tc LEO), which belongs to the cnidarian-specific clade cnidops. Interestingly, molecular work has found a high number of opsin genes in box jellyfish, especially in the Caribbean species Tripedalia cystophora, most of which are of unknown function. In the current study, we raised antibodies against three out of five opsins identified from transcriptomic data from T. cystophora and used them to map the expression patterns. These expression patterns suggest one opsin as the photopigment in the slit eyes and another as a putative photoisomerase found in photoreceptors of all four eyes types. The last antibody stained nerve-like cells in the tentacles, in connection with nematocytes, and the radial nerve, in connection with the gonads. This is the first time photopigment expression has been localized to the outer segments of the photoreceptors in a cnidarian ocellus (simple eye). The potential presence of a photoisomerase could be another interesting convergence between box jellyfish and vertebrate photoreceptors, but it awaits final experimental proof.

AB - Cubomedusae, or box jellyfish, have a complex visual system comprising 24 eyes of four types. Like other cnidarians, their photoreceptor cells are ciliary in morphology, and a range of different techniques together show that at least two of the eye types—the image-forming upper and lower lens eyes—express opsin as the photopigment. The photoreceptors of these two eye types express the same opsin (Tc LEO), which belongs to the cnidarian-specific clade cnidops. Interestingly, molecular work has found a high number of opsin genes in box jellyfish, especially in the Caribbean species Tripedalia cystophora, most of which are of unknown function. In the current study, we raised antibodies against three out of five opsins identified from transcriptomic data from T. cystophora and used them to map the expression patterns. These expression patterns suggest one opsin as the photopigment in the slit eyes and another as a putative photoisomerase found in photoreceptors of all four eyes types. The last antibody stained nerve-like cells in the tentacles, in connection with nematocytes, and the radial nerve, in connection with the gonads. This is the first time photopigment expression has been localized to the outer segments of the photoreceptors in a cnidarian ocellus (simple eye). The potential presence of a photoisomerase could be another interesting convergence between box jellyfish and vertebrate photoreceptors, but it awaits final experimental proof.

KW - box jellyfish

KW - cnidaria

KW - cubozoa

KW - opsin phylogeny

KW - photopigment

KW - phototransduction

KW - vision

U2 - 10.3389/fnana.2022.916510

DO - 10.3389/fnana.2022.916510

M3 - Journal article

C2 - 35991966

AN - SCOPUS:85136462942

VL - 16

JO - Frontiers in Neuroanatomy

JF - Frontiers in Neuroanatomy

SN - 1662-5129

M1 - 916510

ER -