Identification and quantification of spinochromes in body compartments of Echinometra mathaei ’s coloured types

Abstract

Sea urchin pigmentation is mainly due to polyhydroxy-1,4-naphthoquinones called spinochromes. If their molecular structures are well known in test and spines of many species, their abundance and distribution in other body compartments remain unstudied. The aim of this study is to analyse the pigment composition in four body compartments (test/spines, digestive system, gonads and coelomic fluid) of four coloured types of the sea urchin Echinometra mathaei. Qualitative and quantitative measurements by mass spectrometry highlight the existence of 13 different pigments; among which are five isomers of known spinochromes as well as three potentially new ones. The composition comparison shows the largest spinochrome diversity in ‘test/spines’ body compartments. The spinochrome concentrations vary from 48 to 1279 mg kg−1 of dried body compartment. It is the highest in the digestive system, although it is also important in the organic fraction of the ‘test/spines’ body compartment. This observation may be explained by higher exposures of some body compartments to external environments and by the protective role fulfilled by spinochromes against microorganisms, ultraviolet radiation and reactive oxygen species. The ‘black’ type—the most common coloured type in coral reefs—has the highest concentration of spinochromes indicating their importance in Echinoids' fitness by acting as a protective agent.

Genetic manipulation of the pigment pathway in a sea urchin reveals distinct lineage commitment prior to metamorphosis in the bilateral to radial body plan transition

“…Of note is a recent study of pigment in Echinometra mathaei, a species with at least four distinct colored spines. Brasseur et al 26 , characterize the composition of pigments in each color variant, and identified the pigment ratios, the palate of pigments responsible for each color in this animal. Importantly, the ratios of each pigment in the purple variant were similar to those of the purple color of the FMO3-null H. pulcherrimus animals, compared to the green or brown variants.…”

“…pigment chemistry. Pigment in control and FMO3-animals was analyzed as reported 26 by LC-MS with modifications. Briefly, spines were collected from adult animals, dried, crushed, macerated and then suspended in 1.0 ml of aqueous HCl 6 M for 1 h. The sample was then spun 1 minute at high speed in a microfuge and the supernatant was moved to a new tube.…”

Mapping of Spinochromes in the Body of Three Tropical Shallow Water Sea Urchins

“…Their identification was based on their accurate mass, as well as predicted formula (ppm < 10) and compared with the results available in the literature. All of them were already known, but Spinochrome 252 and Spinochrome 282 were first identified by our team in a previous study [31]. Echinamine (8) identification was not clear because of the similarity of structure and mass of Echinamine A and Echinamine B.…”

“…Except in one of our recent works on Echinometra mathaei [31] until now, the complete identification of spinochromes has only been realized from extractions of the external parts of sea urchins, i.e. on the whole organism (including the organic fraction with epidermis, dermis and mesothelium) and spines [16,32].…”

“…The spinochromes inside sea urchins are presently not known. Also, the quantification of spinochromes has only been realized on E. mathaei involving a dried extract weighing method [33] and a mass spectrometry-based quantification method [31]. The present work aims at identifying and quantifying spinochromes in three common sea urchins observed in coral reefs of the Indo-Pacific: Diadema savignyi (Audouin.…”