| dc.description.abstract | Amoebiasis, is a parasitic disease caused by Entamoeba histolytica, causing a wide range of clinical manifestations, from asymptomatic infection to amoebic dysentery and liver abscess, and encystation is a key process enabling this parasite to cause disease. Because encystation of E. histolytica has not been successfully reproduced under laboratory conditions, it is often conducted in surrogate model species. The cyst wall of E. invadens, a model for E. histolytica, is mainly composed of chitin fibrils, two chitin-binding lectins, Jacob that cross-link chitin fibrils and Jessie that self-aggregates on the cyst wall and an enzyme, chitinase, which remodels chitin. Current research aims to identify new biological drugs that can target the cyst formation process but that does not affect human cells. In this study I aimed to study the membrane dynamics of E. invadens during encystation using Langmuir trough apparatus and cell fluctuation analysis. The effect of cyst wall components; chitin and its deacetylated form chitosan on E. invadens plasma membrane lipids (PML) and red blood cells (RBCs) membrane have been studied. I demonstrated that the addition of chitin and chitosan to E. invadens PML has increased the stiffness of plasma membrane lipids and increased the rigidity of RBCs membrane. Furthermore, I aimed to study the effect of Jacob and Jessie lectin on PML and RBCs membrane. Jacob and Jessie were successfully amplified and cloned into an expression vector, however, several experiments to purify these proteins were unsuccessful. This may be due to the protein being unstable and/or toxic to E. coli host, or caused by inefficient transcription, translation and/or posttranslational modifications. In order to resolve these issues, it may be necessary to use different host cells such as mammalian or insect cells. Together, the data presented in this thesis provides evidence that chitin and chitosan contribute to increased rigidity of the lipid monolayer/bilayer. This knowledge in the future may contribute to research aimed at the development of treatments to combat amoebiasis. | en_GB |
