Comparison of pigment composition and melanin content among white, light-green, dark-green, and purple morphs of sea cucumber, Apostichopus japonicus

• Published in: Acta Oceanologica Sinica
• Main Authors: Xing, Lili, Sun, Lina, Liu, Shilin, Li, Xiaoni, Miao, Ting, Zhang, Libin, Yang, Hongsheng
• Format: Report
• Language: English
• Published: SPRINGER 2017
• Subjects: Apostichopus japonicas; pigment composition; color morphs; melanin; pigment content; Oceanography; White Sea
• Online Access: http://ir.qdio.ac.cn/handle/337002/157379; http://ir.qdio.ac.cn/handle/337002/157380; https://doi.org/10.1007/s13131-017-1056-5

Sea cucumber, Apostichopus japonicus (Selenka), is a commercially important marine species in China. Among the differently colored varieties sold in China, white and purple sea cucumbers have the greatest appeal to consumers. Identification of the pigments that may contribute to the formation of different color morphs of sea cucumbers will provide a scientific basis for improving the cultivability of desirable color morphs. In this study, sea cucumbers were divided into four categories according to their body color: white, light green, dark green, and purple. The pigment composition and contents in the four groups were analyzed by high performance liquid chromatography (HPLC). The results show that the pigment contents differed significantly among the white, lightgreen, dark-green, and purple sea cucumbers, and there were fewer types of pigments in white sea cucumber than in the other color morphs. The only pigments detected in white sea cucumbers were guanine and pteroic acid. Guanine and pteroic acid are structural colors, and they were also detected in light-green, dark-green, and purple sea cucumbers. Every pigment detected, except for pteroic acid, was present at a higher concentration in purple morphs than in the other color morphs. The biological color pigments melanin, astaxanthin, beta-carotene, and lutein were detected in light-green, dark-green, and purple sea cucumbers. While progesterone and lycopene, which are also biological color pigments, were not detected in any of the color morphs. Melanin was the major pigment contributing to body color, and its concentration increased with deepening color of the sea cucumber body. Transmission electron microscopy analyses revealed that white sea cucumbers had the fewest epidermal melanocytes in the body wall, and their melanocytes contained fewer melanosomes as well as non-pigmented pre-melanosomes. Sea cucumbers with deeper body colors contained more melanin granules. In the body wall of dark-green and purple sea cucumbers, melanin granules were secreted ...