Leucophores are similar to xanthophores in their specification and differentiation processes in medaka

Abstract

Animal body color is generated primarily by neural crest-derived pigment cells in the skin. Mammals and birds have only melanocytes on the surface of their bodies; however, fish have a variety of pigment cell types or chromatophores, including melanophores, xanthophores, and iridophores. The medaka has a unique chromatophore type called the leucophore. The genetic basis of chromatophore diversity remains poorly understood. Here, we report that three loci in medaka, namely, leucophore free (lf), lf-2, and white leucophore (wl), which affect leucophore and xanthophore differentiation, encode solute carrier family 2, member 15b (slc2a15b), paired box gene 7a (pax7a), and solute carrier family 2 facilitated glucose transporter, member 11b (slc2a11b), respectively. Because lf-2, a loss-of-function mutant for pax7a, causes defects in the formation of xanthophore and leucophore precursor cells, pax7a is critical for the development of the chromatophores. This genetic evidence implies that leucophores are similar to xanthophores, although it was previously thought that leucophores were related to iridophores, as these chromatophores have purine-dependent light reflection. Our identification of slc2a15b and slc2a11b as genes critical for the differentiation of leucophores and xanthophores in medaka led to a further finding that the existence of these two genes in the genome coincides with the presence of xanthophores in nonmammalian vertebrates: birds have yellow-pigmented irises with xanthophore-like intracellular organelles. Our findings provide clues for revealing diverse evolutionary mechanisms of pigment cell formation in animals.

Occurrence of chromatophoroma or chromatophoromatosis inSardinella longiceps(Valenciennes, 1847) from Tamilnadu, southeast coast of India

“…Leucophoroma was not reported earlier in fish. But the leucophoroma lesions observed in this study were compatible with those described by Deravi et al (2014) and Kimura et al (2014), who confirmed that spindloid cells contain light reflectile golden-yellow colour pigment granules.…”

“…() and Kimura et al. (), who confirmed that spindloid cells contain light reflectile golden‐yellow colour pigment granules.…”

Molecular genetic response of Xiphophorus maculatus–X. couchianus interspecies hybrid skin to UVB exposure

“…These genes showed a pattern of up-regulation due to hybridization and also further up-regulation effected by UVB exposure. Among these 18 genes, 4 genes are related to melanin synthesis ( mitfa , tyr , tyrp1a , dct ), 3 genes are related to melanosome transport ( rab27 , rab38a , pmela ), 4 genes are related to pigmentation ( slc2a11b , slc24a5 , oca2, pax3b ), and 4 genes are melanoma/melanocyte marker ( tspan10 , slc45a2 , ptn , 2,8-sialyltranferase ) (Kobayashi et al, 1994; Kuroda et al, 2005; Kang et al, 2007; Zhang et al, 2013; Haltaufderhyde and Oancea 2014; Kimura et al, 2014; Liu et al, 2014; Morice-Picard et al, 2014; Choi et al, 2015; Eaton et al, 2015; Lindsay et al, 2015). The remaining two genes ( CA10 and kirrel3l ) are not well studied and their functions poorly charactrized.…”

Contrasted gene decay in subterranean vertebrates: insights from cavefishes and fossorial mammals

“…Both Lucifuga species had independently fixed LoF mutations in smtla which is known to increase the number of leucophores at the expense of a reduced number of xanthophores in medaka (Fukamachi, et al 2009). In L. dentata, slc2a11b is pseudogenized and this gene codes for a protein that promotes yellow pigmentation (Kimura, et al 2014; Parichy and Spiewak 2015). Two other genes, trpm1a and trpm1b are also pseudogenized in L. dentata .…”