Identification of Melanin in the Mantle of the Pacific Oyster Crassostrea gigas

Abstract

The Pacific oyster, Crassostrea gigas, is widely distributed and is substantially important to shellfish cultivation. Oysters with melanin-colored shells and soft parts are increasingly popular and are of high economic value. However, the distribution and synthesis of melanin in C. gigas remains unclear and there have been only few relevant studies on it. In this study, transmission electron microscopy (TEM) was used to observe melanin in the epidermis of dark mantle tissue. Melanocytes containing melanosomes were observed below the epidermis, suggesting the possibility of a gradual transfer of melanin from the mantle tissue to the epithelium. The frozen section technique and three melanin staining methods were used to confirm the presence of melanin. The results suggest that enzyme identification (DOPA) is a suitable method of melanin staining in the mantle tissues of C. gigas. This study preliminarily identified the existence of melanin in the mantle tissues of C. gigas and is a foundation for the study of melanin synthesis. Furthermore, it provides new insights into the mechanism of shell color formation.

Interactive Effects of Lanthanum and Calcium on Cadmium Accumulation in Wheat with Special Reference to TaNramp5 Expression Regulated by Calmodulin

“…A significant La–Ca interaction and La–Ca–Cd interplay on the accumulation of Cd were found in wheat (Table ). La shares physical similarity with Ca and Cd. , A previous study indicated that La can bind with CaM . CaM alters its conformation and dynamics upon binding with La 3+ .…”

“…Likewise, similar results were observed in the present work (Figure ), and there was a significant La–Cd interaction on Cd accumulation in wheat (Table ). For the phenomenon, a possible reason is the competition between La and Cd for adsorption and absorption sites because of their similar ionic radius. , Likely, another reason underlying a significant La–Cd interaction on Cd accumulation in wheat could be related to La decreasing Cd uptake and upward translocation through the downregulation of TaNramp5 and TaHMA2 …”

“…This might be explained by the La−Cd antagonism as a result of their similar ionic radius. 15,16 Interestingly, our results indicated that 7.2 μM La supply under Ca deficiency more obviously induced wheat growth compared to that under a normal Ca level, and a significant La−Ca interaction on wheat plant growth was also observed (Table 1). The similar findings have been reported by Weng et al, 18 who found that La mitigates the symptoms of Ca deficiency in cucumber (Cucumis sativus L.) and cabbage (Brassica campestris L.).…”

“…13,14 La has special physical and chemical properties because of its similar ionic radius (1.06 Å) to those of Ca 2+ (0.99 Å) and Cd 2+ (0.97 Å). 15,16 La can occupy the Ca position and also substitute bound Ca. 17 The Ca deficiency symptoms of plants can be mitigated by La addition.…”

“…REs often have stronger binding affinity to proteins than Ca because of their greater electropositivity . Lanthanum (La), as one of the most important REs, can promote plant growth and crop yield. , La has special physical and chemical properties because of its similar ionic radius (1.06 Å) to those of Ca 2+ (0.99 Å) and Cd 2+ (0.97 Å). , La can occupy the Ca position and also substitute bound Ca . The Ca deficiency symptoms of plants can be mitigated by La addition .…”