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Krishna S, Woodrow CJ, Staines HM, Haynes RK, Mercereau-Puijalon O. Re-evaluation of how artemisinins work in light of emerging evidence of in vitro resistance. Trends Mol Med 2006; 12:200-5. [PMID: 16616639 PMCID: PMC2682190 DOI: 10.1016/j.molmed.2006.03.005] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2006] [Revised: 03/02/2006] [Accepted: 03/27/2006] [Indexed: 11/18/2022]
Abstract
There are more than half a billion cases of malaria every year. Combinations of an artemisinin with other antimalarial drugs are now recommended treatments for Plasmodium falciparum malaria in most endemic areas. These treatment regimens act rapidly to relieve symptoms and effect cure. There is considerable controversy on how artemisinins work and over emerging indications of resistance to this class of antimalarial drugs. Several individual molecules have been proposed as targets for artemisinins, in addition to the idea that artemisinins might have many targets at the same time. Our suggestion that artemisinins inhibit the parasite-encoded sarco–endoplasmic reticulum Ca2+-ATPase (SERCA) PfATP6 has gained support from recent observations that a polymorphism in the gene encoding PfATP6 is associated with in vitro resistance to artemether in field isolates of P. falciparum.
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Affiliation(s)
- Sanjeev Krishna
- Centre for Infection, Division of Cellular and Molecular Medicine, St. George's, University of London SW17 0RE, UK.
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152
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Chibana H, Mikami Y. [Structural and functional analyses of MRS (major repeated sequnece) in Candida albicans. Application for genotyping and the eternal way to the complete genome sequence]. NIHON ISHINKIN GAKKAI ZASSHI = JAPANESE JOURNAL OF MEDICAL MYCOLOGY 2006; 47:129-34. [PMID: 16940945 DOI: 10.3314/jjmm.47.129] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
There are several different types of repeated sequences in the genome of Candida albicans, including the MRS (Major repeated sequence). In 2004, the whole genome sequence of C. albicans was published. Assembly of the sequences to chromosomal length contigs was not achieved, mainly due to interruption of the sequences by MRS. However, MRS including Ca3, 27A and RPS have been playing important roles in a number of epidemiological studies and basic biological investigations into C. albicans chromosome loss events and associated phenotypic changes. Here we summarize structural analyses from subrepeat sequences to the chromosome level, and functional analyses of MRS.
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Affiliation(s)
- Hiroji Chibana
- Research Center for Pathogenic Fungi and Microbial Toxicoses, Chiba University, Japan.
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153
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Smyth DJ, Glanfield A, McManus DP, Hacker E, Blair D, Anderson GJ, Jones MK. Two isoforms of a divalent metal transporter (DMT1) in Schistosoma mansoni suggest a surface-associated pathway for iron absorption in schistosomes. J Biol Chem 2005; 281:2242-8. [PMID: 16267047 PMCID: PMC1459476 DOI: 10.1074/jbc.m511148200] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
We describe two homologues of the mammalian divalent metal transporter (DMT1) for Schistosoma mansoni, a pathogenic intravascular parasite of humans. Schistosomes have a high nutritional and metabolic demand for iron. Nucleotide sequences of the parasite homologues, designated SmDMT1A and -B, are identical in all but the 5'-regions. The predicted amino acid sequences share at least 60% identity with DMT1 (=Nramp2) of humans, mice, and rats, and at least 55% identity with Nramp1 from mice, humans and Caenorhabditis elegans. SmDMT1A is expressed in differentiating eggs, miracidia, cercariae, schistosomula, and adults, whereas SmDMT1B is expressed in all but the miracidium and occurs at lower levels than SmDMT1A in differentiating eggs and cercariae. An iron-responsive element, present at the 3'-untranslated region of many DMT1 molecules, is not present in schistosome mRNAs studied here. A Western blot analysis of adult worm preparations using a homologous rabbit serum raised against a schistosome DMT1 peptide and a heterologous serum raised against mammalian DMT1, revealed a band approximating 115 kDa. By immunofluorescence microscopy, the schistosome DMT1s localize primarily to the tegument. Iron uptake assays demonstrated that SmDMT1s were able to rescue yeast growth in ferrous iron-transport deficient yeast (fet3fet4). The results suggest that schistosomes express molecules for ferrous iron transport in their tegument, suggesting trans-tegumental transport as one means of iron acquisition for these parasites.
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Affiliation(s)
- Danielle J. Smyth
- Queensland Institute of Medical Research, 300 Herston Road, Herston, Brisbane, 4029, Queensland, Australia
| | - Amber Glanfield
- Queensland Institute of Medical Research, 300 Herston Road, Herston, Brisbane, 4029, Queensland, Australia
- Australian Centre for International and Tropical Health and Nutrition, School of Population Health, The University of Queensland, Queensland 4072 Australia
| | - Donald P. McManus
- Queensland Institute of Medical Research, 300 Herston Road, Herston, Brisbane, 4029, Queensland, Australia
| | - Elke Hacker
- Queensland Institute of Medical Research, 300 Herston Road, Herston, Brisbane, 4029, Queensland, Australia
| | - David Blair
- School of Tropical Biology, James Cook University, Townsville, Queensland 4811, Australia
| | - Greg J. Anderson
- Queensland Institute of Medical Research, 300 Herston Road, Herston, Brisbane, 4029, Queensland, Australia
| | - Malcolm K. Jones
- Queensland Institute of Medical Research, 300 Herston Road, Herston, Brisbane, 4029, Queensland, Australia
- School of Molecular and Microbial Sciences, The University of Queensland, Queensland 4072 Australia
- To whom correspondence should be addressed: Queensland Institute of Medical Research, PO Royal Brisbane Hospital, Herston, Brisbane, 4029, Queensland, Australia. Tel.: 617-33620406; Fax: 617-33620104; E-mail:
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