Comparative biochemical composition in gonad and adductor muscle of triploid and diploid catarina scallop (Argopecten ventricosus Sowerby II, 1842)

Comparative Analysis of the Biochemical Composition, Amino Acid, and Fatty Acid Contents of Diploid, Triploid, and Tetraploid Crassostrea gigas

Tetraploid oysters are artificially produced oysters that do not exist in nature. The successful breeding of 100% triploid oysters resolved the difficulties of traditional drug-induced triploids, such as the presence of drug residues and a low triploid induction rate. However, little is known concerning the biochemical composition and nutrient contents of such tetraploids. Therefore, we investigated compositional differences among diploid, triploid, and tetraploid Crassostrea gigas as well as between males and females of diploids and tetraploids. The findings indicated that glycogen, EPA, ∑PUFA, and omega-3 contents were significantly higher in triploid oysters than in diploids or tetraploids; tetraploid oysters had a significantly higher protein content, C14:0, essential amino acid, and flavor-presenting amino acid contents than diploids or triploids. For both diploid and tetraploids, females had significantly higher levels of glutamate, methionine, and phenylalanine than males but lower levels of glycine and alanine. In addition, female oysters had significantly more EPA, DHA, omega-3, and total fatty acids, a result that may be due to the fact that gonadal development in male oysters requires more energy to sustain growth, consumes greater amounts of nutrients, and accumulates more proteins. With these results, important information is provided on the production of C. gigas, as well as on the basis and backing for the genetic breeding of oysters.

Expression characteristics and functional analysis of Krüppel-like factor 4 in adductor muscle and mantle of Zhikong scallop Chlamys farreri

Krüppel-like factor 4 (KLF4) is an important transcription factor involving in formation and maintenance of muscles in mammals. However, no data are available on KLF4 function in shellfish muscles which play vital roles in the movement, stress response, and physiology in shellfish. In the present study, we revealed that the Klf4 mRNA of Zhikong scallop Chlamys farreri was expressed in most tissues, which has high level in adductor muscle, mantle, kidney, and testis. Positive signals of the Klf4 mRNA and protein were visible in all skeletal muscle fibers of adductor muscle, and all the cells of C. farreri mantle. Furthermore, the knockdown of Klf4 mRNA in adductor muscle and mantle by means of in vivo RNA interference led to some different phenotypes, including disordered arrangement of muscle fibers in adductor muscle and mantle, abnormal structures of skeletal muscles, and reduced muscle fibers under endepidermis of mantle. Our findings demonstrated that Klf4 plays important roles in maintenance of muscle functions in C. farreri adductor muscle and mantle, and suggested that its regulatory way in skeletal muscle may be different from the smooth muscle in shellfish.

Influence of ploidy and metal-metal interactions on the accumulation of Ag, Cd, and Cu in oysters Crassostrea gigas thunberg

The present study was designed to compare the response to contaminants in diploid with triploid specimens of the oyster Crassostrea gigas. The reproduction investment in bivalve molluscs has priority on somatic growth. Thus, genetic sterilization by triploidy induction enables the energy flux to be directed toward somatic growth and glucide storage. Bioaccumulation was examined for Ag (10 microg/L), Cd (10 microg/L), and Cu (30 microg/L) to determine if the response to metals follows similar patterns in diploid (2n) and triploid (3n) groups. The effect of ploidy was also evaluated as a function of dry weight of soft tissue and condition index. Moreover, the reciprocal influence of these metals on their incorporation was studied. The results showed that the major factor governing the degree of metal bioaccumulation by oysters is the nature of the metal introduced in the experimental medium. Thus, the uptake of Cd is proportionally more important than in the case of Ag and even more in Cu. For Cu-treated samples, the influence of ploidy on weight and metal body burden (and Cu concentration) was not significant, whereas for Ag and Cd, significant differences according to genetic type were evidenced by higher tissue weight and lower concentrations in triploid than diploid specimens. Metal-metal interactions study especially showed a reciprocal antagonism between Ag and Cu.