Studies on Body Color Expression of Cultured Black Tiger, Prawn

通过对养殖对虾（Penaeus monodon）外骨骼和肌肉上皮中类胡萝卜素和胡萝卜素蛋白含量的分析，建立改善其体色的策略。首先，测定了不同体色对虾外骨骼中类胡萝卜素的含量和组成。外骨骼中类胡萝卜素含量为2.3 ~ 33.1mg/100g，体色深度与类胡萝卜素含量基本一致。主要的类胡萝卜素虾青素以三种形式存在，即双酯、单酯和游离形式。其次，从外骨骼中纯化出120kDa的蓝色胡萝卜素蛋白。用胶原酶溶液从肌肉上皮中分离出另一个21.4kDa。最后，对深灰色对虾和蓝色对虾的类胡萝卜素进行了分析和比较。用胶原酶溶液提取，从肌肉上皮中释放出蓝色胡萝卜素蛋白，在组织中留下另一种类胡萝卜素。胡萝卜素蛋白部分的类胡萝卜素主要为游离虾青素，其含量在两组对虾间无显著差异。由于残留的类胡萝卜素主要由虾青素酯组成，在去除蓝色胡萝卜素蛋白后，肌肉上皮变红。深灰色组中剩余的红色类胡萝卜素的总含量是蓝色组的六倍。因此，养殖黑虎对虾体色的不同可能是由于肌肉上皮中蓝色胡萝卜素蛋白和红色类胡萝卜素组分的组成不同所致。

Carotenoids and carotenoproteins in the exoskeleton and the muscular epithleium of cultured black tiger prawn Penaeus monodon were analyzed to establish a strategy to improve their body color. First, carotenoid content and composition in the exoskeleton of the prawns exhibiting different body colors were determined. A consistency was observed between the depth of body color and the carotenoid content of 2.3-33.1mg/100g in the exoskeleton. The major carotenoid, astaxanthin, existed in three forms, namely diester, monoester, and free ones. Second, a blue carotenoprotein of 120kDa was purified from the exoskeleton. Another of 21.4kDa was also isolated from the muscular epithelium with a collagenase solution. Finally, carotenoids in both fractions were analyzed and compared between dark gray and blue prawns. A blue carotenoprotein fraction was liberated from the muscular epithelium by extraction with a collagenase solution, leaving another carotenoid fraction in the tissue. The main carotenoid in the carotenoprotein fraction was free astaxanthin, of which content showed no significant difference between the two prawn groups. The muscular epithelium after removal of blue carotenoprotein turned red owing to the remaining carotenoids which were composed largely of astaxanthin esters. The total content of the remaining red carotenoids was about six-fold higher in the dark gray than blue group. Thus the different body color of cultured black tiger prawns is suggested to be due to the varied composition of the blue carotenoprotein and red carotenoid fractions in the muscular epithelium.