Plant cysteine proteinases (CPs) from papaya, pineapple, and some fig species are capable of killing parasitic nematode worms in vitro and also possess anthelmintic effects in vivo by a mechanism different to all commercially available synthetic anthelmintics. There exists, nonetheless, a vast repository of as yet untested plant resources with potential for development into novel anthelmintics. For screening purposes, parasitic nematodes are not an ideal animal model mainly because of the need to maintain complex life-cycles in the laboratory, involving passage through infected animals as well as ensuing costs and ethical considerations. A cheap and effective rapid Caenorhabditis elegans-based assay for screening plant CP extracts for nematicidal activity has been developed based on neutral red retention colorimetric assay. More sensitive ways of identifying nematicidal activity of plant products were explored using wild type and different mutant and transgenic strains. These methods involved assessments of behavioural end points (e.g. motility), lethality and cuticular damage. The effect of CPs on wild type (Bristol N2) and cystatin null mutant (cpi-l-t- and cpi-2-t-) C. e/egans was concentration-, temperature- and time-dependent. (Ps were able to induce elevated cpi-l and cpi- 2 cystatin expression thereby suggesting that c. elegans deploy cystatins CPI-l and CPI-2 to resist CP attack. When taken together, the results of lethality, motility assays and cuticle damage in wild type, bacterially unswollen (bus) strains and cpi-null mutants point towards a cheap and effective rapid through-put C. e/lgans-based assay for screening the nematicidal activities of plant-derived CPs.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:662196 |
| Date | January 2013 |
| Creators | Phiri, Andrew Malata |
| Publisher | University of Nottingham |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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