A Preliminary Study on the Pattern, the Physiological Bases and the Molecular Mechanism of the Adductor Muscle Scar Pigmentation in Pacific Oyster Crassostrea gigas

Abstract

The melanin pigmentation of the adductor muscle scar and the outer surface of the shell are among attractive features and their pigmentation patterns and mechanism still remains unknown in the Pacific oyster Crassostrea gigas. To study these pigmentation patterns, the colors of the adductor muscle scar vs. the outer surface of the shell on the same side were compared. No relevance was found between the colors of the adductor muscle scars and the corresponding outer surface of the shells, suggesting that their pigmentation processes were independent. Interestingly, a relationship between the color of the adductor muscle scars and the dried soft-body weight of Pacific oysters was found, which could be explained by the high hydroxyl free radical scavenging capacity of the muscle attached to the black adductor muscle scar. After the transcriptomes of pigmented and unpigmented adductor muscles and mantles were studied by RNAseq and compared, it was found that the retinol metabolism pathway were likely to be involved in melanin deposition on the adductor muscle scar and the outer surface of the shell, and that the different members of the tyrosinase or Cytochrome P450 gene families could play a role in the independent pigmentation of different organs.

Transcriptomic and proteomic analyses of genetic factors influencing adductor muscle coloration in QN Orange scallops

“…As discussed earlier, CYP450 may affect orange coloration through the accumulation of different pigments in QN Orange scallops. In the Pacific oyster, CYP450 has been found to be differentially expressed in oysters with black tissues, suggesting that the CYP450 gene may be involved in melanogenesis [33]. Thus the possibility that CYP450 affects orange coloration through the accumulation of melanin in QN Orange scallops can not be excluded.…”

Genome-wide association and transcriptome studies reveal the segregation mechanism of mantle markings in three-way cross hybrid abalone

“…Similar studies have shown strong positive genetic correlations (correlation coefficient range of 0.59-0.70) between growth related traits and body color in banana shrimp (Fenneropenaeus merguiensis) (Nguyen et al, 2014). In the Pacific oyster, the adductor muscle scar color was correlated with the soft-body dry weight, so the black adductor muscle scar may be a potential breeding character that could be used to obtain a larger soft-body dry weight (Yu et al, 2017). In some species of Drosophila, the melanin in the body is associated with heat resistance and has wound healing and immune functions (Rajpurohit et al, 2008).…”

“…For example, the boring giant clam (Tridacna crocea) is polymorphic for mantle color, and the survival rate of the blue strain was significantly lower than the yellow-green strain (Zhou et al, 2021). In the black and white shell varieties of the Pacific oyster (Crassostrea gigas), the relationship between the color of the adductor muscle scars and the dried soft-body weight can be explained by the high hydroxyl free radical scavenging capacity of the muscle attached to the black adductor muscle scar (Yu et al, 2017). Genetic introgression caused by interspecific hybridization can lead to the segregation of pigment traits in progeny.…”

Regulation of adductor muscle growth by the IGF-1/AKT pathway in the triploid Pacific oyster, Crassostrea gigas

“…Therefore, the formation and development of AM has a very important effect on the growth and diet of oysters. On the other hand, AM produces large amounts of melanin, and it is reported that the more melanin in the shell, the higher the dry weight of oysters (Yu et al 2017;Hao et al 2015;Xiao yan et al 2003). Melanin removes free radicals and reduces damage to AM, which allows AM to open larger shells and filter out more algae to speed up growth.…”