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Antibacterial Earthworms E-mail
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Sunday, 25 February 2007

Antibacterial Earthworms




By Edwin L. Cooper, Xichun Zhang, Zhang Yi

Faculty of bioengineering,Jimei University,Xiamen 361021, Fujian Province, P.R. of China

In recent years, antimicrobial peptides have become recognized as important contributors to nonspecific host defense for both vertebrates and invertebrates. The value of antimicrobial peptides lies in their ease and speed of synthesis, their broad specificity against prokaryotic cells and their general lack of toxicity for eukaryotic hosts. Thus, they serve as a first-line defense against microbial invasion, supplementing the humoral and cellular immune system. Many different kinds of antimicrobial peptides, which possess antimicrobial activity against bacteria, fungi and enveloped viruses with little or no cytolytic activity, have been isolated from diverse sources [1,2]. In the 700 million years of existence, earthworms have evolved in the environment replete with microorganisms, some of which threatening their existence. To survive in such an environment, they have developed efficient defense mechanisms against invading microorganisms. Such defenses are present in the coelomic fluid of earthworms. The antimicrobial activity in the coelomic fluid is partly attributed to some proteins, such as lysozyme and fetidins. Antibacterial peptides must provide function in earthworm innate immunity, which has been reported [8,9,10]. Those research focus on the identification of antibacterial peptides, mechanism of expression and the molecular character and activity. Though progresses have got in the studying of antibacterial peptides from earthworm, more detail biological role in vivo, the structure-function relationship, extention, activity and toxicity to human or other mammals are unknown. More research needs attention. Firstly, it is essential to obtain enough sample peptides for detailed analysis. Because of the difficulties to purify natural peptides from earthworm directly, for example, the total amount of purified Lumbricus I recovered was 0.1?g per g earthworm, expression of the antibacterial peptides in E. coli or yeast by efficient methods. Secondly, the detail biological role, also the toxicity should be considered, for example, the antitumour activity has been found in several antibacterial peptides. On earthworm, the antitumour activity of F-1 and F-2 were probed with MTT assay and by scanning electron microscopy. F-1 and F-2 played antitumour activity to MGC803 cells (p< 0.05) and morphological changes are observed. Analysis of toxicity is necessary before molecular and clinical investigations. Finally, the molecular design and protein engineering will be the important research interests after analysis of structure-function relationships. Earthworm, as a natural resource, is easy to obtain and a convenient animal model. It will provide clinical therapy and a source of antibacterial peptides in the future and a theoretical contribution to understanding innate immunity.


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