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Protocol for Plasmodium falciparum Infections in Mosquitoes and Infection Phenotype Determination
Published on: July 4, 2007
Microtubule number and length determine cellular shape and function in Plasmodium
Benjamin Spreng1, Hannah Fleckenstein1, Patrick Kübler1
1Integrative Parasitology, Center for Infectious Diseases, Heidelberg University Medical School, Heidelberg, Germany.
Abstract:
Microtubules are cytoskeletal filaments essential for many cellular processes, including establishment and maintenance of polarity, intracellular transport, division and migration. In most metazoan cells, the number and length of microtubules are highly variable, while they can be precisely defined in some protozoan organisms. However, in either case the significance of these two key parameters for cells is not known. Here, we quantitatively studied the impact of modulating microtubule number and length in Plasmodium, the protozoan parasite causing malaria. Using a gene deletion and replacement strategy targeting one out of two α-tubulin genes, we show that chromosome segregation proceeds in the oocysts even in the absence of microtubules. However, fewer and shorter microtubules severely impaired the formation, motility and infectivity of Plasmodium sporozoites, the forms transmitted by the mosquito, which usually contain 16 microtubules. We found that α-tubulin expression levels directly determined the number of microtubules, suggesting a high nucleation barrier as supported by a mathematical model. Infectious sporozoites were only formed in parasite lines featuring at least 10 microtubules, while parasites with 9 or fewer microtubules failed to transmit.
Insights
Malaria parasite (Plasmodium) sporozoite infectivity depends on microtubule number and length. Fewer than 10 microtubules prevent the formation of infectious sporozoites, impacting disease transmission.
Area of Science:
- Cell Biology
- Parasitology
- Biophysics
Background:
- Microtubules are crucial cytoskeletal components involved in diverse cellular functions.
- The precise role of microtubule number and length in cellular processes remains largely unknown.
- Plasmodium, the malaria parasite, offers a unique model for studying microtubule regulation.
Purpose of the Study:
- To quantitatively investigate the impact of microtubule number and length on Plasmodium development and infectivity.
- To understand the relationship between alpha-tubulin expression and microtubule dynamics.
- To determine the minimum microtubule requirements for the formation of infectious Plasmodium sporozoites.
Main Methods:
- Gene deletion and replacement strategies targeting alpha-tubulin genes in Plasmodium.
- Quantitative analysis of microtubule parameters (number and length) in different parasite lines.
- Assessment of sporozoite formation, motility, and infectivity.
- Mathematical modeling to explore microtubule nucleation barriers.
Main Results:
- Chromosome segregation in oocysts can occur independently of microtubules.
- Reduced microtubule number and length significantly impair sporozoite formation, motility, and infectivity.
- Alpha-tubulin expression levels directly correlate with microtubule number, suggesting a high nucleation barrier.
- A minimum of 10 microtubules is required for the generation of infectious sporozoites; fewer result in non-infectious forms.
Conclusions:
- Microtubule number is a critical determinant of Plasmodium sporozoite infectivity.
- The study elucidates the quantitative relationship between microtubule parameters and parasite transmission.
- Findings highlight the importance of precise microtubule regulation for parasite survival and disease transmission.
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