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PMID:8126090

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Citation

de Jesus, AR, Cooper, R, Espinosa, M, Gomes, JE, Garcia, ES, Paul, S and Cross, GA (1993) Gene deletion suggests a role for Trypanosoma cruzi surface glycoprotein GP72 in the insect and mammalian stages of the life cycle. J. Cell. Sci. 106 ( Pt 4):1023-33

Abstract

We have explored the biological function of a surface glycoprotein (GP72) of Trypanosoma cruzi by studying a null mutant parasite, generated by targeted gene deletion. GP72 deletion affected parasite morphology in several stages of the life cycle. Insect midgut (epimastigote) forms had a detached flagellum (apomastigote) in the null mutant. The abnormal flagellar phenotype persisted during development of the infective (metacyclic) forms but there was no impairment in the acquisition of complement resistance, sialidase expression or cell infectivity. The GP72 null mutant could efficiently infect and proliferate in mouse macrophages and non-phagocytic L6E9 cells. The mammalian stages of the life cycle also showed major morphological abnormalities. During early subcultures in L6E9 cells, few extracellular fully flagellated forms, expressing markers characteristic of trypomastigotes, were seen. The extracellular population consisted almost exclusively of rounded forms with short flagella (micromastigote), which expressed an amastigote-specific surface marker and no sialidase. The propagation of the parasite was not affected, despite the apparent lack of the trypomastigote forms, which are thought to be primarily responsible for cell invasion. After some subcultures, the extracellular population changed to about equal numbers of micromastigotes and a range of flagellated forms that still did not include true trypomastigotes. Instead, the kinetoplast remained close to the nucleus and the flagellum emerged from the middle of the cell (mesomastigote). Half of the flagellum adhered to the cell body and the remainder was free at the anterior end. In Triatoma infestans, the survival of the mutant was dramatically reduced, suggesting that either GP72 itself, or the altered properties of the flagellum, were critical for establishment in the insect vector.

Links

PubMed

Keywords

Animals; Fluorescent Antibody Technique; Gene Deletion; Genes, Protozoan/genetics; Insect Vectors/parasitology; Macrophages/parasitology; Mice/parasitology; Microscopy, Electron, Scanning; Morphogenesis/genetics; Neuraminidase/analysis; Phosphoproteins/genetics; Protozoan Proteins/genetics; Rats; Triatoma/parasitology; Trypanosoma cruzi/cytology; Trypanosoma cruzi/genetics; Trypanosoma cruzi/growth & development; Trypanosoma cruzi/ultrastructure

Significance

Annotations

Gene product Qualifier GO Term Evidence Code with/from Aspect Extension Notes Status

TRYCR:Q03876

GO:0050839: cell adhesion molecule binding

ECO:0000315:

F

Figure 4A shows the wildtype flagellum completely attached to the cell body, while Figure 4B shows the Gp72 null mutant with a partially detached flagellum. These figures show that the protein Gp72 is necessary for complete flagellum attachment to the cell body of Trypanosoma cruzi.

complete
CACAO 9934

See also

References

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