Stimulation of giant freshwater prawn (Macrobrachium rosenbergii ) to generate the antimicrobial substances - analysis of the cecroin - like peptide

• Main Authors: Chia-Zong Lin, 林佳蓉
• Other Authors: Huei-Jen Tsai; Yen-Ling Song
• Format: Others
• Language: zh-TW
• Published: 1994
• Online Access: http://ndltd.ncl.edu.tw/handle/40549448621971771034

碩士 === 國立臺灣大學 === 漁業學系 === 82 === Cecropin A, cecropin P1 and lysozyme susceptibilities of the common aquatic pathogens were tested with an inhibition zone assay. Results showed that cecropins could inhibit growth of the 16 stains of bacteria, including Aeromonas hydrophila, A. salmo- nicida, Escherichia coli, Vibrio alginolyticus, V. anguillarum, V. carchariae, V. damsela, V. fluvialis, V. harveyi, V. ordalii , V, parahemolytics, V. tubiashii and V. vulnificus. Cecropins also inhibited growth of 2 pathogenic yeast stains, Debaryomyces hansenii. However, antibacterial activities of cecropins could not reach to Edwardsiella tarda, as well as, V. vulnificus strains isolated from a diseased eel. Microbicidal activity pro- vided by the lysozyme only acted on D. hansenii. We used the inhibition zone assay to detecte the presence of antimicrobial substances produced by giant freshwater prawn (Ma- crobrachium rosenbergii). When prawn were injected into the peri- cardial cavity with E. coli cells, hemolymph were collected at 1,2,3,4,5,6,12,18,24,48,72 hours post-injection. Assay of the partially purified and concentrated plasma on E. coli agarose plate showed an induced bacterial substance(s). The antibacterial activity appeared in 31% of tested prawn plasma 6 hrs post- injection. Same activity was shown in 79% of tested plasma 24 hrs post-injection. However, it was not detected in all tested plasma 72 hrs post-injection. It suggests that most of the prawn will synthesize antibacterial substance(s) once stimulated. However, this activity was short-term and concentration was estimated no more than 0.21uM in prawn plasma. Western blot analysis of plasma with an antibacterial acti- vity showed an induced 35kd substance when it was stained with a rabbit-anti-cecropin A serum. These results indicated that the antibacterial substance induced in giant freshwater prawn may be a cecropin- like.