Scanning and transmission electron microscopy of Trypanosoma congolense epimastigotes attached to a plastic substratum shows them to elaborate a complex flagellum filament system and plaque with a highly organized structure. Non-ionic detergent extraction of these cells shows that the resulting cytoskeletons remain attached to the plaque. The subpellicular corset of microtubules can be removed by salt or Ca2+ treatment leaving the axoneme, paraflagellar rod, associated filaments and the plaque. Neither of these treatments therefore removed the plaque-associated material from the substratum. Analysis of these fractions by SDS-polyacrylamide gel electrophoresis reveals an abundant 70 kDa protein that is highly enriched in the salt extracted 'minimal plaque' structures and appears likely to be a major constituent of this structure. These studies reveal that the complex filament and microtubule systems of the cytoskeleton involved the attachment of trypanosomes to substrata and have established a method of biochemical fractionation of the structures and components involved.
This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
A small proportion of individuals infected with Plasmodium falciparum develop cerebral malaria. Why it affects some infected individuals but not others is poorly understood. Since tumor necrosis factor (TNF) has been implicated strongly in the pathogenesis of cerebral malaria, here we have compared different parasite isolates for their ability to induce TNF production by human mononuclear cells in vitro. Wild isolates were collected from 34 Gambian children with cerebral malaria and 66 children with uncomplicated malaria fever. Cerebral malaria isolates tended to stimulate more TNF production than mild malaria isolates, but there was considerable overlap between the two groups, and the present data provide only limited support for the hypothesis that cerebral malaria is caused by strains of P. falciparum inducing high levels of TNF. However, it is notable that the amounts of TNF induced by different wild isolates from a single locality differed by over 100-fold. The biological significance of this polymorphism deserves further scrutiny in view of the central role that TNF is believed to play in host defense and in the clinical symptomatology of human malaria.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.