Identification and Characterization of Highly Fluorescent Pigment Cells in Embryos of the Arabian Killifish (Aphanius Dispar).

Atyaf Hamied,Christian Hacker,Qusay Alnedawy,Hisashi Hashimoto,Tetsuhiro Kudoh,Mark Ramsdale,Ana Correia

doi:10.1016/j.isci.2020.101674

Abstract

SummaryThe Arabian killifish, Aphanius dispar, is a small tropical teleost fish living in wide range of habitats in sea water and fresh water in the Middle East. Here, we report extraordinary fluorescent pigment cells in the Arabian killifish embryo. These cells appear brown in transmitted light, yellowish white in reflected light, and as strong fluorescence in GFP and RFP filters. TEM and confocal microscopy analyses show the fluorescence emanates from leucosome-like pigment organelles. The cells express the gene encoding GTP cyclohydrolase (gch), a marker for leucophores and xanthophore. Gene knockdown and knockout of gch using morpholino or CRISPR-Cas9 induced loss of fluorescence in these embryos, indicating a crucial role of the enzyme and the associated pterine biosynthesis pathway in the generation of the fluorescence. We concluded that these cells are a highly fluorescent subtype of leucophores and have named them as fluoroleucophores.

Highlights

There are a variety of pigment cells in fish that create specific color patterns in each species and protect the body from strong light (Armstrong et al, 2000; Kapp et al, 2018)
SUMMARY The Arabian killifish, Aphanius dispar, is a small tropical teleost fish living in wide range of habitats in sea water and fresh water in the Middle East
Gene knockdown and knockout of gch using morpholino or CRISPR-Cas9 induced loss of fluorescence in these embryos, indicating a crucial role of the enzyme and the associated pterine biosynthesis pathway in the generation of the fluorescence. We concluded that these cells are a highly fluorescent subtype of leucophores and have named them as fluoroleucophores

Summary

Introduction

There are a variety of pigment cells in fish that create specific color patterns in each species and protect the body from strong light (Armstrong et al, 2000; Kapp et al, 2018). The difference is not always obvious, leucophores are generally considered to reflect light of all wavelengths producing a white color, whereas iridophores commonly create a broad wave length reflectors appearing silvery (Frohnhofer et al, 2013; Fujii, 1993) The differences between these pigment cells can be distinguished by examination of pigment organelles by TEM: Melanophores possess dark pigment granules with circular or oval shapes (Fujii, 1993). Xanthophores contain pterinosomes, which are circular granules with relatively pale contrast (Fujii, 1993)

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