Preliminary Study On Cause Of Carotenoids Enriched In Orange Adductor Individuals In The Noble Scallops Chlamys Nobilis Neeve

The noble scallop Chlamys nobilis Neeve is famious for its vivid shell color including orange, purple, brown, orange-purple etc. It is naturally distributed in Japan, Indonesia, and the southern sea of China. It has also been one of most important cultured shellfish in the southern sea of China since late 1980s because of its quick growth, short culturing period, high profit and good taste and nutrition. The most important edible part of the noble scallop is adductor, which usually display white. However, very few of the noble scallops have orange adductor. Comparing with white adductors, the orange adductors are more inviting to customer due to their noble appearance and abundance.Carotenoids are usually defined as C40 hydrocarbon(carotene) and their oxidative derivatives (xanthophyll), produced by plant, algae and microorganism, and widely distributed in the nature's kingdom. Carotenoids often display orange or red color and are commonly used as additive and functional foods because of their bioactivity and antioxidant activity. They also grant animal colorful appearance which affect consumers'preference and animals'market value. Most animals can not synthetize carotnoids themselves and must obtain from their diet. Hence, it is significant to clarify how the individuals with orange adductor accumulate carotenoids from point of heredity, physiology, and environment, which will provide guideline for breeding of the noble scallop.In the paper, the cause of orange individuals enriched carotenoids were studied using two kinds of different scallops with orange adductor (orange shell) and white adductor (brown shell) from heredity, physiology, and environment And the main results are as follow:1. Adductor color can be inherited steadily. Two kind of families were established, whose parents were either white adductor or orange adductor by mating one male to one female. The result showed that the adductor color could be inherited steadily, and orange may be dominant to white. The orange color in adductor is linkage with orange shell color for orange adductor only occurred in scallops with orange shell.2. The ability to enrich carotnoid in orange adductor scallop can be inherited steadily. The TCC in tissues of orange shell (orange adductor) and brown shell (white adductor) individuals were test and compared, finding that TCC in orange shell individuals was higher than that in brown ones, we speculate that the TCC was at least partly controlled by genes. In F₁ and F₂ generations, the TCC in orange shell scallops was still higher than brown shell scallops, from which we concluded that the ability to accumulate carotenoid in orange scallops could be inherited steadily.3. The TCC in orange individuals can be improved by artificial selection. The TCC in F₁ and F₂ was tested and compared with their own parents, finding that the TCC in white adductor families had no significant change, however, it got a remarkable improvement in orange adductor families; In F₁ of orange adductor families, TCC was improved 57% and 93% improvement for tissues adductor and mantle respectively. As for F₂, the TCC was close to F₁ in adductor and higher than F₁ in mantle(310.63μg/g).4. The TCC in orange individuals can be affected by physiology factors. Orange adductor families were used to study the influence of gonad development and age on the TCC.1) The TCC in adductor, mantle and gonad was remarkedly affected by gonad development. The TCC in gonad increased from 120.61μg/g to 303.07μg/g for immature male scallop and from 419.83μg/g to 591.00μg/g for immature female scallop respectively. The TCC in mantle only changed in immature female scallop decreasing from 327.18μg/g to 257.96μg/g. The TCC in adductor decreased from 124.34μg/g to 118.09μg/g for immature male scallop and from 130.10μg/g to 112.83μg/g for immature female scallop respectively. Analysis of variance demonstrated that gonad developmental level, scallop gender, and maturing time all made significant impact on the TCC in gonad, and their interactions were also significant.2) The TCC in adductor and mantle was affected by age. The TCC of tested tissues in 16-month old scallops had same level with that in 4-month old scallops with exception of gonad, whose TCC was higher in 16-month old scallops than 4-month old ones. The TCC in 28-month scallops was subjected to great decrease for all tested tissues and significantly lower than the young scallops.5. The TCC in orange individuals can be affected by environmental factors. Orange adductor families were used to study the influence of diet (Isochrysis zhanjiangensis, Platymonas subcordiformis, Nitzschia closterium f. minutissima, I. Zhanjiangensis+P. subcordiformis, I. Zhanjiangensis+N. closterium f. minutissima), temperature, salinity, seasonal change on the TCC in orange adductor family.1) The TCC is related to algae. At beginning, the TCC was 521.98μg/g and 101.13μg/g in gonad and adductor respectively, increased to 567.99μg/g and 63.36μg/g for Isochrysis zhanjiangensis + P. subcordiformis, 581.90μg/g and 81.82μg/g for P. subcordiformis, 599.87μg/g and 78.30μg/g for Isochrysis zhanjiangensis + N. closterium f. minutissima, 614.56μg/g and 73.54μg/g for N. closterium f. minutissima; 552.61μg/g and 72.37μg/g for Isochrysis zhanjiangensis after four weeks culturing.2) TCC in tested tissues was significantly affected by temperature. After three weeks experiment, TCC in gonad and adductor increased to 556.79μg/g and 108.31μg/g under 19℃, 509.29μg/g and 82.18μg/g under 24℃, 599.99μg/g and 55.53μg/g under 29℃.3) TCC in tested tissues was significantly affected by salinity. After three weeks experiment, TCC in adductor and gonad decreased to 498.33μg/g and 81.94μg/g at 26‰, to 519.459μg/g and 118.37μg/g at 21‰respectively. Most scallops at 21‰were died after two weeks experiment.4) TCC varied at different seasons. TCC in all tested tissues achieved to their highest in spring, decreased in summer and autumn, began to increase in winter. The highest TCC of female and male scallop could reach to 122.26μg/g and 138.86μg/g in adductor, 256.57μg/g and 312.98μg/g in mantle, 729.30μg/g and 394.66μg/g in gonad. The change of TCC in different seasons might be affected by temperature and gonad development, the micro algae might have less impact on the TCC, since little change occurred to abundance and kinds of micro algae in different seasons.It is for the first time to prove that: 1) the adductor color in marine mollusk could be inherited steadily; 2) TCC enriched in bivalve can be inherited and improved by means of artificial selection.