Origin of adult‐type pigment cells forming the asymmetric pigment pattern, in Japanese flounder (Paralichthys olivaceus)

Abstract

The flatfish-specific asymmetric pigment pattern depends on the asymmetric appearance of adult-type pigment cells after the late metamorphic stages. To understand the mechanism enabling the formation of this asymmetric pattern, we investigated the behavior of pigment cell latent precursors in postembryonic Japanese flounder, Paralichthys olivaceus, by analysis of the expression patterns of pigment lineage markers (colony stimulating factor 1 receptor, dopachrome tautomerase, kit) and the DiI (DiO) labeling test for latent precursors. We found that, throughout the larval stages, pigment cell latent precursors were predominantly localized along the dorsal and ventral margins of the flank symmetrically and migrated continuously from these regions to the lateral sides symmetrically, and after late metamorphic stages these precursors differentiated into adult-type pigment cells on the lateral side asymmetrically. We conclude that adult-type pigment cells that form the asymmetric pigment pattern are continuously derived from the dorsal and ventral margins of the flank during larval development. Developmental Dynamics 239:3147-3162,

Morphological and Molecular Characterization of Dietary-Induced Pseudo-Albinism during Post-Embryonic Development of Solea senegalensis (Kaup, 1858)

“…As occurs with mitf, pax3 also promotes and inhibits melanogenesis through transcriptional regulation of cKit [30]. CKit plays a critical role in melanocyte physiology by influencing melanogenesis, migration and survival of these cells [32] and it is primarily expressed in the melanized melanophores [13]. In Senegalese sole developing larvae, the profile of cKit/pax3 and mitf / pax3 ratios reflected the pattern of melanophore ontogeny [15].…”

“…This could be an indication of new tissue devoid of chromatophores (or cells devoid of pigment) being produced basally and that the early leucophores located basally disappeared (Fig. 4F) [13].…”

“…While molecular signaling towards the differentiation of new populations of melanophores, xanthophores and iridophores occurs during pro-metamorphosis (11–19 dph), morphological changes occur later at post-metamorphosis [15]. Considering that the amount and proportions of these chromatophores were similar in pigmented and pseudo-albino specimens until 27 dph, and that their number remained invariable from that day onwards, it seemed that pigment cell precursors were likely influenced by the asymmetric signaling during pro-metamorphosis rather than in mature larval chromatophores [13]. The decrease in xanthophores from 33 to 35 dph observed in pseudo-albinos was likely the result of the degradation of already existent xanthophores.…”

“…Indeed, fish have been used as models for melanoma research because it has been shown tissues within fish share molecular signatures and histopathological features with human cancers [6]. The genetics of pigmentation have been explored in several model teleost fish including zebrafish [7], [8], medaka [9], fugu [10], goldfish [11], [12] and, recently, in flatfish [13], [14], [15]. Flatfish are particularly useful to analyze the origin of pigmentation disorders during the ontogeny because altered pigmentation can be induced under intensive rearing conditions [16], [17], [18], [19].…”

Metamorphosis in Teleosts

“…In flounder, pigment cell precursors migrate symmetrically to both lateral sides from the bases of fins at the dorsal and ventral margins of the flank, yet these cells differentiate as melanophores only on the ocular side (Watanabe et al, 2008; Yamada, Okauchi, & Araki, 2010). The genetic bases for this differential response of pigment cells remain unknown.…”