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To prepare calcium-binding peptides, the flesh residue of Mactra Veneriformis was subjected to enzymatic hydrolysis. By comparing the capability of combining calcium of the hydrolyzates, pepsin was confirmed to be the most suitable enzyme for hydrolyzing the flesh residue to release calcium-binding peptides among the seven tested proteases. The pepsin hydrolyzate (PHM) was divided into three fractions according to the molecule weight of its composition, which ranged from 0.5 to 15 kDa. The low-molecule-weight fraction named PHM-3 had the highest capability in combining calcium. The peptides existing in the PHM-3 fraction consisted of higher contents of Glu, Ala and Leu, and could produce one type of calcium-peptide complex by powerfully chelating calcium ions. PHM-3 products could effectively increase calcium absorption and retention while they decreased the calcium excretion in animal tests. Additionally, symptoms caused by low calcium bioavailability in ovariectomized rats, such as bone mineral density reduction and mechanical strength loss could be significantly ameliorated by the hydrolytic products addition in diet. 相似文献
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文蛤、青蛤和四角蛤蜊的随机扩增多态性DNA(RAPD)的比较分析 总被引：10，自引：0，他引：10
利用随机扩增多态性DNA(RAPD)技术，对吕四海区的三种重要的水产贝类：文蛤、青蛤和四角蛤蜊的遗传多样性进行了分析和比较。用60个随机引物对三种贝类共24个样品进行随机扩增，从中选取了45个扩增效果比较稳定的引物用于群体分析，共得到了250个位点。根据Nei氏公式计算出3种贝类种间和种内的遗传相似性指数和相对遗传距离，并进行聚类分析。通过比较分析，3种贝类之间的遗传距离差异不大。相对与青蛤和四角蛤蜊，文蛤种内的遗传距离要小。 相似文献
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A laboratory-based microcosm experiment was carried out to examine both the behavioral and antioxidant response of the clam Gomphina veneriformis under the conditions of 3 types of burial material(sand,silt,silt-sand mixture) with 3 burial depths(5 cm,15 cm,30 cm).The concentration of dissolved oxygen decreased significantly after 3 d of burial in all experimental groups.In silt and sand-silt mixture groups,the interstitial water quality became worsened with lower pH,and higher NH_4~+-N concentration,where clam mortality occurred simultaneously.However,clam samples in all sand groups and 5 cm,15 cm sand-silt mixture groups survived well for 8 d.Obviously fewer individuals left in the bottom sand in the 15 cm,30 cm silt groups and 30 cm sand-silt mixture groups than in the 5 cm groups.Therefore,it suggests that adding silt and increasing burial depth could stimulate the vertical movement of organisms and cause lethal effects.It was found that the burial depth was the key factor that influenced the activities of antioxidant enzymes,such as superoxide dismutase(SOD) and catalase(CAT).The SOD and CAT activities in the gills and hepatopancreases of organisms both showed significant upregulation in 30 cm burial depth after buried for 8 d.Higher enzyme activities were found in gills than in hepatopancreases,which indicated that the gills of the bivalve G.veneriformis were more susceptible to burial effects than hepatopancreases.Overall,this study shows that sediment burial could cause effects on the biological behavior and antioxidant enzyme activities. 相似文献
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１９９１年８月在大家洼老河口滩面上，长竹蛏、四角蛤蜊大批死亡，中潮区以上死亡率达１００％，最大感染强度一个病贝寄生３６４个胞囊。通过调查发现这二种贝的资源受到极大破坏，死因是由于一种刺缘吸虫的囊蚴寄生所致，寄生部位主要是鳃、外套膜和斧足。民囊直径平均为３８７ｕｍ，囊蚴头领发达，头棘２３枚，排成一列，背部中央无间断，腹吸盘发达，位于身体中前腹部，平均体长７８０μｍ，宽２９０μｍ。 相似文献
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采用毒理学实验方法,比较研究了Cd~(2+)和Hg~(2+)对四角蛤蜊(Mactra veneriformis Reeve)急性毒性效应的差异,以期为进一步评价重金属离子对四角蛤蜊的毒性效应和作用机理等提供理论依据.死亡概率单位和实验液浓度对数的线性回归分析表明,Cd~(2+)对四角蛤蜊在24、48和96 h的半致死浓度(LC_(50))分别为15.961、5.149和2.383 mg/L,Hg~(2+)的LC_(50)分别为3.714、0.607和0.207 mg/L;Cd~(2+) 和Hg~(2+) 对四角蛤蜊的安全质量浓度分别为0.023 8 mg/L和0.002 1 mg/L,分别是我国渔业水质标准(GB11607-89)限定量的4.76倍和4.02倍. 相似文献
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