Successful modification | The parasite was generated by the genetic modification |
The mutant contains the following genetic modification(s) |
Gene disruption,
Gene disruption,
Introduction of a transgene,
Introduction of a transgene
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Reference (PubMed-PMID number) |
Reference 1 (PMID number) : 21098480 |
MR4 number |
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Parent parasite used to introduce the genetic modification |
Rodent Malaria Parasite | P. berghei |
Parent strain/line | P. berghei ANKA |
Name parent line/clone |
P. berghei ANKA 2.34
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Other information parent line | P. berghei ANKA 2.34 is a cloned, gametocyte producer line of the ANKA strain (PubMed: PMID: 15137943). |
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The mutant parasite was generated by |
Name PI/Researcher | A.Z. Tremp; J.T. Dessens |
Name Group/Department | Department of Pathogen Molecular Biology, Faculty of Infectious and Tropical Diseases |
Name Institute | London School of Hygiene & Tropical Medicine |
City | London |
Country | UK |
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Name of the mutant parasite |
RMgm number | RMgm-602 |
Principal name | IMC1h/b-dKO |
Alternative name | |
Standardized name | |
Is the mutant parasite cloned after genetic modification | Yes |
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Phenotype |
Asexual blood stage | Not different from wild type |
Gametocyte/Gamete | Not different from wild type |
Fertilization and ookinete | Normal numbers of ookinetes are produced. Mature ookinetes showed abnormal morphology. Ookinetes were wider, shorter and possessed a bulging area typically in the central part of the cell. Gliding motility of ookinetes was reduced. Infectivity of ookinetes was reduced (ookinetes produced ~98-fold less oocysts in A. stephensi). |
Oocyst | Infectivity of ookinetes was reduced (ookinetes produced ~98-fold less oocysts in A. stephensi). Oocysts appeared to develop normally, forming large numbers of sporozoites. However, all sporozoites were of abnormal shape, typically possessing a bulging area near the middle of the sporozoite. No sporozoites were detected in salivary glands. |
Sporozoite | Infectivity of ookinetes was reduced (ookinetes produced ~98-fold less oocysts in A. stephensi). Oocysts appeared to develop normally, forming large numbers of sporozoites. However, all sporozoites were of abnormal shape, typically possessing a bulging area near the middle of the sporozoite. No sporozoites were detected in salivary glands. |
Liver stage | Not tested |
Additional remarks phenotype | Mutant/mutation
The mutant lacks expression of Inner membrane complex protein 1h (IMC1h) and inner membrane complex protein 1b (IMC1b). This 'double knock-out' mutant has been obtained by genetic crossing the single imc1h knock-out mutant (RMgm-601) with the single imc1b knock-out mutant (RMgm-147).
Protein (function)
The imcb1h and imcb1b genes belongs to small 'family' of conserved genes that express putative membrane skeleton proteins which contain domains that share sequence homology to domains of articulins, proteins of membrane skeleton of free-living protists and show homology to the inner membrane complex protein 1 (TgIMC1) of the subpellicular network of Toxoplasma gondii tachyzoites (Khater, E.I., et al. 2004, J. Cell. Biol. 167, 425-32) . In Plasmodium eight conserved IMC1 protein family members have been identified, named IMC1a-IMC1h. Two of these, IMC1a and IMC1b, were shown to be differentially expressed in sporozoites and ookinetes, respectively, and to form part of their pellicle structures in P. berghei. IMC1a and IMC1b are structurally and functionally homologous and involved in parasite morphology, mechanical strength, gliding motility and infectivity, in accordance with their roles as membrane skeleton proteins (see also mutanst RMgm-147 and RMgm-148 lacking expression of IMC1b and IMC1a). IMC1h, is found in the pellicle of both ookinetes and sporozoites (see mutant RMgm-600) and acts in a very similar way to IMC1b and IMC1a. It plays a role in in morphology/shape of ookinetes and sporozoites and in motility of both stages. See mutant RMgm-601 which lacks expression of IMC1h and see below
Phenotype
Phenotype analyses of a mutant lacking IMC1h (RMgm-601, IMC1h-sKO) indicate a role of this protein in morphology/shape of ookinetes and sporozoites and in motility of both stages.
Phenotype analyses of a mutant lacking IMC1b (RMgm-147) indicate a role of this protein in morphology/shape and motility of ookinetes.
Analysis of a mutant lacking expression of both IMC1h and IMC1b (IMC1h/b-dKO) provides evidence that for a direct involvement of IMC1 proteins in gliding motility uncoupled from cell shape. The shape IMC1h/b-dKO ookinetes was not significantly different to that of IMC1h-sKO ookinetes (RMgm-601). Thus, IMC1h-KO ookinete cell shape appears not to be further affected by the additional imc1b gene disruption. Both gliding motility and infectivity of IMC1b/h-dKO were more strongly reduced compared to IMC1h-sKO ookinetes. The morphology of IMC1b/h-dKO sporozoites was similar to that of IMC1h-sKO sporozoites. These phenotype analyses of a mutant lacking expression of both IMC1h and IMC1b provides evidence that for a direct involvement of IMC1 proteins in gliding motility uncoupled from cell shape.
Additional information
Cell death in response to osmotic shock was increased in the IMC1b/h-dKO ookinetes compared to the IMC1h-sKO. These results indicate that IMC1h, like IMC1b, is involved in the mechanical stability of ookinetes, which is consistent with it being an ookinete membrane skeleton component. It also indicates that there is a cumulative effect of multiple ookinete-specific imc1 gene disruptions on the ookinetes’ mechanical strength. Both gliding motility and infectivity of IMC1b/h-dKO were more strongly reduced compared to IMC1h-sKO ookinetes.
Other mutants
RMgm-147: A mutant lacking expression of IMC1b
RMgm-148: A mutant lacking expression of IMC1a
RMgm-163: A mutant expressing a GFP-tagged form of IMC1b
RMgm-600: A mutant expressing a GFP-tagged form of IMC1h
RMgm-601: A mutant lacking expression of both IMC1h
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