LC–MS Metabolomic Profiling of Mantle Tissue Reveals Pigment-Linked Pathways in Pacific Oyster Shell Coloration

While shell color is a vital economic trait of the Pacific oyster (Crassostrea gigas), the metabolic regulation underlying the melanin deposition which influences it remains elusive. Analyses of black shell and white shell oyster strains frequently reflect systemic physiological differences (for example, growth variations) which can obscure localized pigmentary signals. To reduce these systemic confounders, researchers at the School of Fisheries at Ludong University (Yantai, China) characterized metabolic profiles of excised black and white mantle tissue regions (the dark outer ring of the oyster itself, where theoyster forms its shell) ⁽¹⁾within oysters to identify direct pigment-related metabolic signatures. Untargeted liquid chromatography-mass spectrometry (LC-MS) metabolomics was used to identify 527 differential metabolites. A paper based on this work was published in Comparative Biochemistry and Physiology Part B: Biochemistry and Molecular Biology. ⁽²⁾

An important species in the worldwide aquaculture industry, the Pacific oyster’s market value is heavily influenced by the coloration of shell coloration, with a rich array of distinct shell color strains, including golden, purple, black, and white, having been established through the process of long-term selective breeding. ^(3-6) The current data suggests that the color of the shell strains reveal variations in growth performance and nutritional characteristics, with black shell strains showing noteworthy possibility for additional selective improvement. ^(7,8) While it had been determined that shell pigmentation in mollusks is regulated by the mantle and is closely associated with melanin, ^(9,10) the exact metabolic regulation of these pigment variations remain in doubt, hence inspiring the Ludong University research. ⁽²⁾

The researchers report that their assessment showed that, in black mantle regions tyrosine metabolism was altered, and, while dopamine concentrations remained stable, catecholamine-related metabolites were downregulated. At the same time, elevated glutathione concentrations were identified in black mantle regions, which may create a reductive microenvironment which assists in the maintenance of redox homeostasis during melanogenesis. An increase in spermidine concentrations were also identified in black mantle regions, which may indirectly modulate melanogenesis. Additionally, citrate cycle intermediates and lipids in black mantle regions were downregulated, which suggests a metabolic shift to support high-intensity biosynthesis. ⁽²⁾

“These findings,” write the authors of the paper, ⁽¹⁾ “provide a novel biochemical perspective on mollusk coloration, highlighting that melanin pigmentation is a highly regulated metabolic process that balances substrate competition, redox regulation, and energy allocation.” They believe that their discoveries can provide new insights into the biochemical basis of shell coloration and may aid in the development of selective breeding strategies targeting pigmentation traits in bivalves. ⁽²⁾

Read More on Similar Topics

Chromatographic and LC–MS/MS Identification of Selenium-Enriched Oyster Peptides with Potent ACE Inhibitory and Antihypertensive Activity

References

1. Oyster Anatomy Laboratory, Internal Anatomy: Observation and Investigation. Maryland Sea Grant website. https://www.mdseagrant.org/interactive_lessons/oysters/labs/internal_anatomy_lab.html (accessed 2025-10-09)
2. Jia, X.; Zhang, X.; Zhang, H. et al. Region-Specific Metabolomics Reveals the Mechanisms Underlying Melanin Synthesis in Pacific Oyster (Crassostrea gigas) Mantle. Comp Biochem Physiol B Biochem Mol Biol. 2026, 111205. DOI: DOI: 10.1016/j.cbpb.2026.111205
3. B. Li, B.; K. Song, K.; J. Meng, J. et al. Integrated Application of Transcriptomics and Metabolomics Provides Insights into Glycogen Content Regulation in the Pacific Oyster Crassostrea gigas. BMC Genomics2017, 18, 713. DOI: 10.1186/s12864-017-4069-8
4. Xu, C.; Li, Q.; Yu, H. et al. Inheritance of Shell Pigmentation in Pacific Oyster Crassostrea gigas. Aquaculture2019, 512, 734249. DOI: 10.1016/j.aquaculture.2019.734249
5. Han, Z.; Li, Q. Relationship Between Shell Color and Growth and Survival Traits in the Pacific Oyster Crassostrea gigas. J. Ocean Univ. China2021, 20, 985-991. DOI: 10.1007/s11802-021-4676-5
6. Song, J.; Li, Q.; Kong, L.; Yu, H. Identification of Candidate AFLP Markers for Shell Color of the Pacific Oyster (Crassostrea gigas) Under Artificial Selection. Biochem. Syst. Ecol. 2016, 66, 209-215. DOI: 10.1016/j.bse.2016.04.012
7. L. Xu, L.; Q. Li, Q.; H. Yu, H. et al. Estimates of Heritability for Growth and Shell Color Traits and their Genetic Correlations in the Black Shell Strain of Pacific Oyster Crassostrea gigas. Marine Biotechnol. 2017, 19, 421-429. DOI: 10.1007/s10126-017-9772-6
8. Zhu, Y.; Li, Q.; Yu, H. et al. Biochemical Composition and Nutritional Value of Different Shell Color Strains of Pacific Oyster Crassostrea gigas. J. Ocean Univ. China2018, 17, 897-904. DOI: 10.1007/s11802-018-3550-6
9. Boettiger, A.; Ermentrout, B.; Oster, G. The Neural Origins of Shell Structure and Pattern in Aquatic Mollusks. Proc. Natl. Acad. Sci. U. S. A. 2009, 106, 6837-6842. DOI: 10.1073/pnas.0810311106
10. Hu, B.; Yu, H.; Xu, C. et al. Shell Colour Diversity in Marine Molluscs: From Current Knowledge to Future Aquaculture Applications. Rev. Aquac.2025, 17, e70038. DOI: 10.1111/raq.70038