Plasmodium trophozoite

Shenai BR, Sijwali PS, Singh A et al (2000) Characterization of native and recombinant falcipain-2, a principal trophozoite cysteine protease and essential hemoglobinase of Plasmodium falciparum. J Biol Chem 275 29000-29010... 

Anti-malarial activity of desferrioxamine has been demonstrated in a range of Plasmodium species under in vitro conditions and more importantly under in vivo conditions in rat [87] and man [88], Desferrioxamine causes reversible effects during early ring stage and late schizont stages of the life cycle. In contrast, irreversible cytocidal effects occur when cultures at the late trophozoite/early schizont stage are exposed to the chelator [89,90]. Primary lesions are associated with the nucleus which is consistent with a perinuclear localization for ribonucleotide reductase [88]. 

The malarial parasite, Plasmodium falciparum, was grown in red blood cells to the late trophozoite stage. Cells isolated by centrifugation were lysed with saponin, and the intact parasites were resuspended in 10 mM Hepes-KOH buffer (pH 8.0) at a dilution of 1 3. 

Survival of parasites is partly due to their high rate of reproduction, which may be either sexual or asexual some organisms such as Plasmodium exhibit both forms of reproduction in their life cycle. Simple fission is characteristic of many amoeba, but some species also undergo nuclear division in the cystic state (cysts are forms required for survival outside the host) with each nucleus giving rise to new trophozoites (the growing, motile and pathogenic form). 

Later as a result of the investigation of Archibold and Ross [33a] and others, it has been shown that dapsone (and its repository forms) could clear the blood from trophozoites of different plasmodium spp. The sensitivity of the different species of parasites varied P. falciparum is very sensitive, while P. vivax is less so. Their action, as with sulphonamides, is mainly against the blood stages with marginal activity against primary (pre-erythrocytic) tissue forms and no activity against sexual and latent tissue forms. It has also been shown that dapsone potentiated the action of pyrimethamine, and a combination of the two markedly delayed the development of... 

Although PS accounts for less than 5% of Plasmodium lipids, it is a key intermediate in the synthesis of PE, which serves as a precursor to PC (see above). PS is synthesized by a condensation of serine with CDP-DAG catalyzed by PS synthase (PSS). Initially, PSS was characterized biochemically in P. knowlesi and later P. falciparum (Elabbadi and Vial, personal communication). Two putative genes that possibly encode PSS have been identified in the P. falciparum genome base and a recombinant protein has been made. In P. falciparum, the putative PSS gene is transcribed during the ring and trophozoite stages. PS decarboxylation via PS decarboxylase (PSD) was first demonstrated in P. knowlesi-miected red cells where it was found that radiolabeled serine was incorporated into Etn (Elabbadi et ah, 1997). 

In most cells, the ratio between GSH and its oxidized form, GSSG, is usually between 10 1 and 100 1 and is mainly achieved by the action of GR (Becker et al., 2003b). In the host cell compartment containing trophozoites of P. falciparum, the GSH/GSSG ratio was decreased to approximately 28 whereas in the normal red cell and the Plasmodium the value is around 300, indicating a redox burden on the host cell compartment. In addition, this oxidative burden is reflected by a... 

Cooper, R. A., Papakrivos, J., Lane, K. D., Fujioka, H., Lingelbach, K., and Wellems, T. E. (2005). PfCG2, a Plasmodium falciparum protein peripherally associated with the parasi-tophorous vacuolar membrane, is expressed in the period of maximum hemoglobin uptake and digestion by trophozoites. Mol. Biochem. Parasitol. 144,167-176. 

Huff, C. G., and Coulston, F. (1944). The development of Plasmodium gallinaceum from sporozoite to erythrocytic trophozoite. J. Infect. Dis. 75, 231-249. 

Miller, L. H. (1969). Distribution of mature trophozoites and schizonts of Plasmodium falciparum in the organs of Aotus trivirgaius, the night monkey. Am. J. Trop. Med. Hyg. 18, 860-865. 

Wood, B. R., Langford, S. J., Cooke, B. M., Glenister, F. K., Lim, J., and McNaughton, D. (2003). Raman imaging of hemozoin within the food vacuole of Plasmodium falciparum trophozoites. FEBS Lett. 554,247-252. 

Depletion of polyamines by the bis(benzyl)polyamines and ODC inhibitors prevents transformation of trophozoites to schizonts (25, 27-29). Similarly, inhibition of growth with bis(benzyl)polyamines has been observed for Leishmania (30). These observations strongly suggest that enzyme product interactions have a role in regulation of polyamine biosynthesis in Plasmodium spp. and Leishmania spp. However, L. donovani ODC, unlike the mammalian enzyme, is not negatively regulated by polyamines (16). 

Bozdech, Z., Zhu, J., Joachimiak, M. P., Cohen, F. E., Pulliam, B., and DeRisi, J. L., 2003, Expression profiling of the schizont and trophozoite stages of Plasmodium falciparum with a long-oligonucleotide microarray. Genome Biol 4 R9. 

Trophozoite Vegetative form of a protozoan such as Plasmodium. 

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