| Summary: | 碩士 === 國立海洋大學 === 生物科技研究所 === 91 === Abstract：
Antimicrobial peptides（AMPs）are small cationic molecules that play an important role in innate host defense mechanism of living organisms including plants, vertebrates and invertebrates against invading microorganisms such as bacteria, fungi, parasites and virus.
Monodoncin is a member of AMPs isolated from the haemocyte of black tiger shrimp, Penaeus monodon, a mature peptide with 55 residues and 5.8-kDa MW. It contains with a proline-rich amino-terminal domain and a carboxyl-domain containing six cysteines. It has an inhibitory effect on gram negative bacteria. In the present study the genomic DNA contains 1338 bp including two exon and one intron with 676 bp. Monodoncin has inhibitory effect on Gram+ Aeroccus viridan and fungi Fusarium pisi、Fusarium oxysporum. The electron microscopic study demonstrates the interaction and disruption of the cell membrane causing the killing of the pathogens. Monodoncin gene is expressed during early larval stages, starting from Nauplius III and continues throughout the development. It is mainly expressed in haemocytes and highly detected on carapace by immunohistochemistry . Twelve hours after Gram-negative. bacteria Vibrio alginolyticus and Gram-positive bacteria Aeroccus viridan challenge, the Monodoncin gene expression of RNA level reaches to the highest in haemocytes, intestine and gill, coincident with the residue bacteria count decreasing to the lowest level at 24 hours post-challenge in the treated shrimp. In addition, there is a change in the expression of a 4-KDa peptide suggested to be a processing form of Monodoncin. Furthermore, injection of synthesized Monodocin and Cecropin B（Hyalophora cecropia）to white spot virus infected-tiger shrimp delay the death progression due to transport stress and virus infection.
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