This study aimed to evaluate the potential impacts of an introduced clam Mercenaria mercenaria on estuarine ecosystem, and implications for the niche competition with a native clam Meretrix meretrix. The biodeposition...This study aimed to evaluate the potential impacts of an introduced clam Mercenaria mercenaria on estuarine ecosystem, and implications for the niche competition with a native clam Meretrix meretrix. The biodeposition, respiration, and excretion rates of 34. mercenaria were determined seasonally using a sediment trap and a closed respirator in field. The biodeposition rates ofM. mercenaria were 0.06-0.37 g/ （ind.·d）, and the respiration rates were 0.31-14.66 mg/（ind.·d）. The ammonia and phosphate excretion rates were 0.18-36.70 and 1.44-14.87 μg/（ind.·d）, respectively. The hard clam M. mercenaria may discharge dry deposits up to 2.1 × 10^5 t, contribute 18.3 t ammonia and 9.0 t phosphate to culture ponds, and consume 7.9×10^3 t O2 from ponds annually. It suggested that the hard clam M. mercenaria might play an important role in pelagic-benthic coupling in pond ecosystem through biodeposition and excretion. A comparison of the key physiological parameters of the introduced clam M. mercenaria and the native clam Meretrix meretrix suggested that M. mercenaria had a niche similar to that of Meretrix meretrix in Shuangtaizi estuary and might have a potential competition with Meretrix meretrix for habitat and food ifM. mercenaria species escaped from the culture pond or artificially released in estuarine ecosystem.展开更多
Serotonin (5-HT) has been found to stimulate meiotic maturation of oocytes in many molluscs. During maturation, several signaling pathways are involved, especially the phosphatidylinositol and cAMP pathways. In order ...Serotonin (5-HT) has been found to stimulate meiotic maturation of oocytes in many molluscs. During maturation, several signaling pathways are involved, especially the phosphatidylinositol and cAMP pathways. In order to examine the possible role of the phosphatidylinositol signaling pathway in regulating oocyte maturation in Mercenaria mercenaria, the effects of the activator/inhibitor of phospholipase (PLC) and protein kinase C (PKC) on serotonin-induced maturation were studied. Results show that high-concentrations of neomycin (inhibitor of PLC) blocked oocyte maturation, while 9, 10-dimethyl-1, 2-benzanthracene (DMBA, activator of PLC) promoted oocyte maturation in the presence of serotonin. It was also found that in the presence of serotonin, phorbol 12-myristate 13-acetate (PMA, activator of PKC) inhibited oocyte maturation, while sphingosine (inhibitor of PKC) stimulated oocyte maturation. These results indicate that serotonin-induced oocyte maturation requires the activation of the phosphatidylinositol pathway. Decrease of PLC inhibited serotonin-induced oocyte maturation, whereas a decrease of PKC stimulated the maturation. Thus, our study indicates that serotonin promotes maturation of M. mercenaria oocytes through PLC stimulated increase in calcium ion concentration via inositol-1, 4, 5-trisphosphate (IP3) but not PKC.展开更多
Hard clams Mercenaria mercenaria were introduced from America to China in 2000. In this paper, the contents of 18 common acids,protein, fat as well as vitamines and mineral ions in edible part of hard calm were analyz...Hard clams Mercenaria mercenaria were introduced from America to China in 2000. In this paper, the contents of 18 common acids,protein, fat as well as vitamines and mineral ions in edible part of hard calm were analyzed. The results showed that the contents of 18 common acids and the essential amino acid were 52.42% and 40.88% respectively and the average score of essential amino acid was 96.4±11.3 according to the FAO/WHO suggested level (1973), and in which the smelled amino acid takes about 48.30%. The content of protein in edible part of hard clam was higher(60.69%) and the content of fat was much lower(5.60%) than that of some bivalves. The results also indicated that the edible part of hard clam was also rich in amino acids, vitamins(A, B1,B2,B5,B6), and mineral ions such as Ca,Zn,Fe,Mn, etc. Hard clam was suggested to be with higher nutritional value which was good for human health.展开更多
基金Supported by the National Special Research Fund for Non-Profit Marine Sector(No.201305043)the Key Laboratory for Ecological Environment in Coastal Areas,State Oceanic Administration(No.201311)+1 种基金the Collaborative Innovation Center for Zhejiang Marine High-Efficiency and Healthy Aquaculturethe K.C.Wong Magna Fund at Ningbo University
文摘This study aimed to evaluate the potential impacts of an introduced clam Mercenaria mercenaria on estuarine ecosystem, and implications for the niche competition with a native clam Meretrix meretrix. The biodeposition, respiration, and excretion rates of 34. mercenaria were determined seasonally using a sediment trap and a closed respirator in field. The biodeposition rates ofM. mercenaria were 0.06-0.37 g/ （ind.·d）, and the respiration rates were 0.31-14.66 mg/（ind.·d）. The ammonia and phosphate excretion rates were 0.18-36.70 and 1.44-14.87 μg/（ind.·d）, respectively. The hard clam M. mercenaria may discharge dry deposits up to 2.1 × 10^5 t, contribute 18.3 t ammonia and 9.0 t phosphate to culture ponds, and consume 7.9×10^3 t O2 from ponds annually. It suggested that the hard clam M. mercenaria might play an important role in pelagic-benthic coupling in pond ecosystem through biodeposition and excretion. A comparison of the key physiological parameters of the introduced clam M. mercenaria and the native clam Meretrix meretrix suggested that M. mercenaria had a niche similar to that of Meretrix meretrix in Shuangtaizi estuary and might have a potential competition with Meretrix meretrix for habitat and food ifM. mercenaria species escaped from the culture pond or artificially released in estuarine ecosystem.
基金Supported by the National High Tecnhology Research and Development Program of China (863 Program) (No. 2004AA603810)
文摘Serotonin (5-HT) has been found to stimulate meiotic maturation of oocytes in many molluscs. During maturation, several signaling pathways are involved, especially the phosphatidylinositol and cAMP pathways. In order to examine the possible role of the phosphatidylinositol signaling pathway in regulating oocyte maturation in Mercenaria mercenaria, the effects of the activator/inhibitor of phospholipase (PLC) and protein kinase C (PKC) on serotonin-induced maturation were studied. Results show that high-concentrations of neomycin (inhibitor of PLC) blocked oocyte maturation, while 9, 10-dimethyl-1, 2-benzanthracene (DMBA, activator of PLC) promoted oocyte maturation in the presence of serotonin. It was also found that in the presence of serotonin, phorbol 12-myristate 13-acetate (PMA, activator of PKC) inhibited oocyte maturation, while sphingosine (inhibitor of PKC) stimulated oocyte maturation. These results indicate that serotonin-induced oocyte maturation requires the activation of the phosphatidylinositol pathway. Decrease of PLC inhibited serotonin-induced oocyte maturation, whereas a decrease of PKC stimulated the maturation. Thus, our study indicates that serotonin promotes maturation of M. mercenaria oocytes through PLC stimulated increase in calcium ion concentration via inositol-1, 4, 5-trisphosphate (IP3) but not PKC.
文摘Hard clams Mercenaria mercenaria were introduced from America to China in 2000. In this paper, the contents of 18 common acids,protein, fat as well as vitamines and mineral ions in edible part of hard calm were analyzed. The results showed that the contents of 18 common acids and the essential amino acid were 52.42% and 40.88% respectively and the average score of essential amino acid was 96.4±11.3 according to the FAO/WHO suggested level (1973), and in which the smelled amino acid takes about 48.30%. The content of protein in edible part of hard clam was higher(60.69%) and the content of fat was much lower(5.60%) than that of some bivalves. The results also indicated that the edible part of hard clam was also rich in amino acids, vitamins(A, B1,B2,B5,B6), and mineral ions such as Ca,Zn,Fe,Mn, etc. Hard clam was suggested to be with higher nutritional value which was good for human health.
