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Button-Simons KA, Kumar S, Carmago N, Haile MT, Jett C, Checkley LA, Kennedy SY, Pinapati RS, Shoue DA, McDew-White M, Li X, Nosten FH, Kappe SH, Anderson TJC, Romero-Severson J, Ferdig MT, Emrich SJ, Vaughan AM, Cheeseman IH. The power and promise of genetic mapping from Plasmodium falciparum crosses utilizing human liver-chimeric mice. Commun Biol 2021; 4:734. [PMID: 34127785 PMCID: PMC8203791 DOI: 10.1038/s42003-021-02210-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2020] [Accepted: 04/30/2021] [Indexed: 12/30/2022] Open
Abstract
Genetic crosses are most powerful for linkage analysis when progeny numbers are high, parental alleles segregate evenly and numbers of inbred progeny are minimized. We previously developed a novel genetic crossing platform for the human malaria parasite Plasmodium falciparum, an obligately sexual, hermaphroditic protozoan, using mice carrying human hepatocytes (the human liver-chimeric FRG NOD huHep mouse) as the vertebrate host. We report on two genetic crosses-(1) an allopatric cross between a laboratory-adapted parasite (NF54) of African origin and a recently patient-derived Asian parasite, and (2) a sympatric cross between two recently patient-derived Asian parasites. We generated 144 unique recombinant clones from the two crosses, doubling the number of unique recombinant progeny generated in the previous 30 years. The allopatric African/Asian cross has minimal levels of inbreeding and extreme segregation distortion, while in the sympatric Asian cross, inbred progeny predominate and parental alleles segregate evenly. Using simulations, we demonstrate that these progeny provide the power to map small-effect mutations and epistatic interactions. The segregation distortion in the allopatric cross slightly erodes power to detect linkage in several genome regions. We greatly increase the power and the precision to map biomedically important traits with these new large progeny panels.
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Affiliation(s)
- Katrina A Button-Simons
- Eck Institute for Global Health, Department of Biological Sciences, University of Notre Dame, Notre Dame, IN, USA.
| | - Sudhir Kumar
- Center for Global Infectious Disease Research, Seattle Children's Research Institute, Seattle, WA, USA
| | - Nelly Carmago
- Center for Global Infectious Disease Research, Seattle Children's Research Institute, Seattle, WA, USA
| | - Meseret T Haile
- Center for Global Infectious Disease Research, Seattle Children's Research Institute, Seattle, WA, USA
| | - Catherine Jett
- Host Pathogen Interactions Program, Texas Biomedical Research Institute, San Antonio, TX, USA
| | - Lisa A Checkley
- Eck Institute for Global Health, Department of Biological Sciences, University of Notre Dame, Notre Dame, IN, USA
| | - Spencer Y Kennedy
- Center for Global Infectious Disease Research, Seattle Children's Research Institute, Seattle, WA, USA
| | | | - Douglas A Shoue
- Eck Institute for Global Health, Department of Biological Sciences, University of Notre Dame, Notre Dame, IN, USA
| | - Marina McDew-White
- Disease Intervention and Prevention Program, Texas Biomedical Research Institute, San Antonio, TX, USA
| | - Xue Li
- Disease Intervention and Prevention Program, Texas Biomedical Research Institute, San Antonio, TX, USA
| | - François H Nosten
- Shoklo Malaria Research Unit, Mahidol-Oxford Tropical Medicine Research Unit, Mahidol University, Mae Sot, Thailand
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine Research Building, University of Oxford Old Road Campus, Oxford, UK
| | - Stefan H Kappe
- Center for Global Infectious Disease Research, Seattle Children's Research Institute, Seattle, WA, USA
| | - Timothy J C Anderson
- Disease Intervention and Prevention Program, Texas Biomedical Research Institute, San Antonio, TX, USA
| | | | - Michael T Ferdig
- Eck Institute for Global Health, Department of Biological Sciences, University of Notre Dame, Notre Dame, IN, USA
| | | | - Ashley M Vaughan
- Center for Global Infectious Disease Research, Seattle Children's Research Institute, Seattle, WA, USA
| | - Ian H Cheeseman
- Host Pathogen Interactions Program, Texas Biomedical Research Institute, San Antonio, TX, USA.
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2
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Plasmodium Genomics and Genetics: New Insights into Malaria Pathogenesis, Drug Resistance, Epidemiology, and Evolution. Clin Microbiol Rev 2019; 32:32/4/e00019-19. [PMID: 31366610 DOI: 10.1128/cmr.00019-19] [Citation(s) in RCA: 64] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Protozoan Plasmodium parasites are the causative agents of malaria, a deadly disease that continues to afflict hundreds of millions of people every year. Infections with malaria parasites can be asymptomatic, with mild or severe symptoms, or fatal, depending on many factors such as parasite virulence and host immune status. Malaria can be treated with various drugs, with artemisinin-based combination therapies (ACTs) being the first-line choice. Recent advances in genetics and genomics of malaria parasites have contributed greatly to our understanding of parasite population dynamics, transmission, drug responses, and pathogenesis. However, knowledge gaps in parasite biology and host-parasite interactions still remain. Parasites resistant to multiple antimalarial drugs have emerged, while advanced clinical trials have shown partial efficacy for one available vaccine. Here we discuss genetic and genomic studies of Plasmodium biology, host-parasite interactions, population structures, mosquito infectivity, antigenic variation, and targets for treatment and immunization. Knowledge from these studies will advance our understanding of malaria pathogenesis, epidemiology, and evolution and will support work to discover and develop new medicines and vaccines.
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3
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Goodman CD, Siregar JE, Mollard V, Vega-Rodríguez J, Syafruddin D, Matsuoka H, Matsuzaki M, Toyama T, Sturm A, Cozijnsen A, Jacobs-Lorena M, Kita K, Marzuki S, McFadden GI. Parasites resistant to the antimalarial atovaquone fail to transmit by mosquitoes. Science 2016; 352:349-53. [PMID: 27081071 DOI: 10.1126/science.aad9279] [Citation(s) in RCA: 97] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2015] [Accepted: 03/10/2016] [Indexed: 12/16/2022]
Abstract
Drug resistance compromises control of malaria. Here, we show that resistance to a commonly used antimalarial medication, atovaquone, is apparently unable to spread. Atovaquone pressure selects parasites with mutations in cytochrome b, a respiratory protein with low but essential activity in the mammalian blood phase of the parasite life cycle. Resistance mutations rescue parasites from the drug but later prove lethal in the mosquito phase, where parasites require full respiration. Unable to respire efficiently, resistant parasites fail to complete mosquito development, arresting their life cycle. Because cytochrome b is encoded by the maternally inherited parasite mitochondrion, even outcrossing with wild-type strains cannot facilitate spread of resistance. Lack of transmission suggests that resistance will be unable to spread in the field, greatly enhancing the utility of atovaquone in malaria control.
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Affiliation(s)
| | - Josephine E Siregar
- School of BioSciences, University of Melbourne, Melbourne, VIC 3010, Australia. Eijkman Institute for Molecular Biology, JI Diponegoro no. 69, Jakarta, 10430, Indonesia. Department of Biomedical Chemistry, Graduate School of Medicine, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Vanessa Mollard
- School of BioSciences, University of Melbourne, Melbourne, VIC 3010, Australia
| | - Joel Vega-Rodríguez
- Johns Hopkins University Bloomberg School of Public Health, Department of Molecular Microbiology and Immunology, Malaria Research Institute, Baltimore, MD 21205, USA
| | - Din Syafruddin
- Eijkman Institute for Molecular Biology, JI Diponegoro no. 69, Jakarta, 10430, Indonesia. Department of Parasitology, Faculty of Medicine, Hasanuddin University, Jalan Perintis Kemerdekaan Km10, Makassar 90245, Indonesia
| | - Hiroyuki Matsuoka
- Division of Medical Zoology, Jichi Medical University, 3311-1 Yakushiji, Shimotsuke, Tochigi 329-0498, Japan
| | - Motomichi Matsuzaki
- Department of Biomedical Chemistry, Graduate School of Medicine, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Tomoko Toyama
- School of BioSciences, University of Melbourne, Melbourne, VIC 3010, Australia
| | - Angelika Sturm
- School of BioSciences, University of Melbourne, Melbourne, VIC 3010, Australia
| | - Anton Cozijnsen
- School of BioSciences, University of Melbourne, Melbourne, VIC 3010, Australia
| | - Marcelo Jacobs-Lorena
- Johns Hopkins University Bloomberg School of Public Health, Department of Molecular Microbiology and Immunology, Malaria Research Institute, Baltimore, MD 21205, USA
| | - Kiyoshi Kita
- Department of Biomedical Chemistry, Graduate School of Medicine, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan. School of Tropical Medicine and Global Health, Nagasaki University, Sakamoto, Nagasaki 852-8523, Japan
| | - Sangkot Marzuki
- Eijkman Institute for Molecular Biology, JI Diponegoro no. 69, Jakarta, 10430, Indonesia
| | - Geoffrey I McFadden
- School of BioSciences, University of Melbourne, Melbourne, VIC 3010, Australia.
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4
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Talman AM, Prieto JH, Marques S, Ubaida-Mohien C, Lawniczak M, Wass MN, Xu T, Frank R, Ecker A, Stanway RS, Krishna S, Sternberg MJE, Christophides GK, Graham DR, Dinglasan RR, Yates JR, Sinden RE. Proteomic analysis of the Plasmodium male gamete reveals the key role for glycolysis in flagellar motility. Malar J 2014; 13:315. [PMID: 25124718 PMCID: PMC4150949 DOI: 10.1186/1475-2875-13-315] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2014] [Accepted: 07/28/2014] [Indexed: 12/22/2022] Open
Abstract
Background Gametogenesis and fertilization play crucial roles in malaria transmission. While male gametes are thought to be amongst the simplest eukaryotic cells and are proven targets of transmission blocking immunity, little is known about their molecular organization. For example, the pathway of energy metabolism that power motility, a feature that facilitates gamete encounter and fertilization, is unknown. Methods Plasmodium berghei microgametes were purified and analysed by whole-cell proteomic analysis for the first time. Data are available via ProteomeXchange with identifier PXD001163. Results 615 proteins were recovered, they included all male gamete proteins described thus far. Amongst them were the 11 enzymes of the glycolytic pathway. The hexose transporter was localized to the gamete plasma membrane and it was shown that microgamete motility can be suppressed effectively by inhibitors of this transporter and of the glycolytic pathway. Conclusions This study describes the first whole-cell proteomic analysis of the malaria male gamete. It identifies glycolysis as the likely exclusive source of energy for flagellar beat, and provides new insights in original features of Plasmodium flagellar organization. Electronic supplementary material The online version of this article (doi:10.1186/1475-2875-13-315) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Arthur M Talman
- Division of Cell and Molecular Biology, Imperial College, London, UK.
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Samarakoon U, Gonzales JM, Patel JJ, Tan A, Checkley L, Ferdig MT. The landscape of inherited and de novo copy number variants in a Plasmodium falciparum genetic cross. BMC Genomics 2011; 12:457. [PMID: 21936954 PMCID: PMC3191341 DOI: 10.1186/1471-2164-12-457] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2011] [Accepted: 09/22/2011] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Copy number is a major source of genome variation with important evolutionary implications. Consequently, it is essential to determine copy number variant (CNV) behavior, distributions and frequencies across genomes to understand their origins in both evolutionary and generational time frames. We use comparative genomic hybridization (CGH) microarray and the resolution provided by a segregating population of cloned progeny lines of the malaria parasite, Plasmodium falciparum, to identify and analyze the inheritance of 170 genome-wide CNVs. RESULTS We describe CNVs in progeny clones derived from both Mendelian (i.e. inherited) and non-Mendelian mechanisms. Forty-five CNVs were present in the parent lines and segregated in the progeny population. Furthermore, extensive variation that did not conform to strict Mendelian inheritance patterns was observed. 124 CNVs were called in one or more progeny but in neither parent: we observed CNVs in more than one progeny clone that were not identified in either parent, located more frequently in the telomeric-subtelomeric regions of chromosomes and singleton de novo CNVs distributed evenly throughout the genome. Linkage analysis of CNVs revealed dynamic copy number fluctuations and suggested mechanisms that could have generated them. Five of 12 previously identified expression quantitative trait loci (eQTL) hotspots coincide with CNVs, demonstrating the potential for broad influence of CNV on the transcriptional program and phenotypic variation. CONCLUSIONS CNVs are a significant source of segregating and de novo genome variation involving hundreds of genes. Examination of progeny genome segments provides a framework to assess the extent and possible origins of CNVs. This segregating genetic system reveals the breadth, distribution and dynamics of CNVs in a surprisingly plastic parasite genome, providing a new perspective on the sources of diversity in parasite populations.
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Affiliation(s)
- Upeka Samarakoon
- Department of Biological Sciences, Eck Institute for Global Health, University of Notre Dame, Notre Dame, IN 46556, USA
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6
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Rayner JC, Liu W, Peeters M, Sharp PM, Hahn BH. A plethora of Plasmodium species in wild apes: a source of human infection? Trends Parasitol 2011; 27:222-9. [PMID: 21354860 PMCID: PMC3087880 DOI: 10.1016/j.pt.2011.01.006] [Citation(s) in RCA: 84] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2010] [Revised: 01/26/2011] [Accepted: 01/27/2011] [Indexed: 01/03/2023]
Abstract
Recent studies of captive and wild-living apes in Africa have uncovered evidence of numerous new Plasmodium species, one of which was identified as the immediate precursor of human Plasmodium falciparum. These findings raise the question whether wild apes could be a recurrent source of Plasmodium infections in humans. This question is not new, but was the subject of intense investigation by researchers in the first half of the last century. Re-examination of their work in the context of recent molecular findings provides a new framework to understand the diversity of Plasmodium species and to assess the risk of future cross-species transmissions to humans in the context of proposed malaria eradication programs.
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Affiliation(s)
- Julian C Rayner
- Malaria Programme, Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge, CB10 1SA, UK.
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7
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Malaria gametocytogenesis. Mol Biochem Parasitol 2010; 172:57-65. [PMID: 20381542 PMCID: PMC2880792 DOI: 10.1016/j.molbiopara.2010.03.019] [Citation(s) in RCA: 159] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2010] [Revised: 03/29/2010] [Accepted: 03/30/2010] [Indexed: 02/07/2023]
Abstract
Male and female gametocytes are the components of the malaria parasite life cycle which are taken up from an infected host bloodstream by mosquitoes and thus mediate disease transmission. These gamete precursors are morphologically and functionally quite distinct from their asexual blood stage counterparts and this is reflected in their distinct patterns of gene expression, cellular development and metabolism. Recent transcriptome, proteome and reverse genetic studies have added valuable information to that obtained from traditional studies. However, we still have no answer to the fundamental question regarding sexual development: 'what triggers gametocytogenesis'? In the current climate of eradication/elimination, tackling transmission by killing gametocytes has an important place on the agenda because most antimalarial drugs, whilst killing asexual blood stage parasites, have no effect on the transmissible stages.
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8
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Ferguson DJP, Campbell SA, Henriquez FL, Phan L, Mui E, Richards TA, Muench SP, Allary M, Lu JZ, Prigge ST, Tomley F, Shirley MW, Rice DW, McLeod R, Roberts CW. Enzymes of type II fatty acid synthesis and apicoplast differentiation and division in Eimeria tenella. Int J Parasitol 2006; 37:33-51. [PMID: 17112527 PMCID: PMC2803676 DOI: 10.1016/j.ijpara.2006.10.003] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2006] [Revised: 09/26/2006] [Accepted: 10/03/2006] [Indexed: 11/16/2022]
Abstract
Apicomplexan parasites, Eimeria tenella, Plasmodium spp. and Toxoplasma gondii, possess a homologous plastid-like organelle termed the apicoplast, derived from the endosymbiotic enslavement of a photosynthetic alga. However, currently no eimerian nuclear encoded apicoplast targeted proteins have been identified, unlike in Plasmodium spp. and T. gondii. In this study, we demonstrate that nuclear encoded enoyl reductase of E. tenella (EtENR) has a predicted N-terminal bipartite transit sequence, typical of apicoplast-targeted proteins. Using a combination of immunocytochemistry and EM we demonstrate that this fatty acid biosynthesis protein is located in the apicoplast of E. tenella. Using the EtENR as a tool to mark apicoplast development during the Eimeria lifecycle, we demonstrate that nuclear and apicoplast division appear to be independent events, both organelles dividing prior to daughter cell formation, with each daughter cell possessing one to four apicoplasts. We believe this is the first report of multiple apicoplasts present in the infectious stage of an apicomplexan parasite. Furthermore, the microgametes lacked an identifiable apicoplast consistent with maternal inheritance via the macrogamete. It was found that the size of the organelle and the abundance of EtENR varied with developmental stage of the E. tenella lifecycle. The high levels of EtENR protein observed during asexual development and macrogametogony is potentially associated with the increased synthesis of fatty acids required for the rapid formation of numerous merozoites and for the extracellular development and survival of the oocyst. Taken together the data demonstrate that the E. tenella apicoplast participates in type II fatty acid biosynthesis with increased expression of ENR during parasite growth. Apicoplast division results in the simultaneous formation of multiple fragments. The division mechanism is unknown, but is independent of nuclear division and occurs prior to daughter formation.
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Affiliation(s)
- D J P Ferguson
- Nuffield Department of Pathology, University of Oxford, John Radcliffe Hospital, Oxford OX3 9DU, UK.
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9
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Furuya T, Mu J, Hayton K, Liu A, Duan J, Nkrumah L, Joy DA, Fidock DA, Fujioka H, Vaidya AB, Wellems TE, Su XZ. Disruption of a Plasmodium falciparum gene linked to male sexual development causes early arrest in gametocytogenesis. Proc Natl Acad Sci U S A 2005; 102:16813-8. [PMID: 16275909 PMCID: PMC1277966 DOI: 10.1073/pnas.0501858102] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
A male gametocyte defect in the Plasmodium falciparum Dd2 parasite was previously discovered through the observation that all progeny clones in a Dd2 x HB3 genetic cross were the result of fertilization events between Dd2 female and HB3 male gametes. A determinant linked to the defect in Dd2 was subsequently mapped to an 800-kb segment on chromosome 12. Here, we report further mapping of the determinant to an 82-kb region and the identification of a candidate gene, P. falciparum male development gene 1 (pfmdv-1), that is expressed at a lower level in Dd2 compared with the wild-type normal male gametocyte-producing ancestor W2. Pfmdv-1 protein is sexual-stage specific and is located on the gametocyte plasma membrane, parasitophorous vacuole membrane, and the membranes of cleft-like structures within the erythrocyte. Disruption of pfmdv-1 results in a dramatic reduction in mature gametocytes, especially functional male gametocytes, with the majority of sexually committed parasites developmentally arrested at stage I. The pfmdv-1-knockout parasites show disturbed membrane structures, particularly multimembrane vesicles/tubes that likely derive from deformed cleft-like structures. Mosquito infectivity of the knockout parasites was also greatly reduced but not completely lost. The results suggest that pfmdv-1 plays a key role in gametocyte membrane formation and integrity.
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Affiliation(s)
- Tetsuya Furuya
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892-8132, USA
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10
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Talman AM, Domarle O, McKenzie FE, Ariey F, Robert V. Gametocytogenesis: the puberty of Plasmodium falciparum. Malar J 2004; 3:24. [PMID: 15253774 PMCID: PMC497046 DOI: 10.1186/1475-2875-3-24] [Citation(s) in RCA: 136] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2004] [Accepted: 07/14/2004] [Indexed: 11/16/2022] Open
Abstract
The protozoan Plasmodium falciparum has a complex life cycle in which asexual multiplication in the vertebrate host alternates with an obligate sexual reproduction in the anopheline mosquito. Apart from the apparent recombination advantages conferred by sex, P. falciparum has evolved a remarkable biology and adaptive phenotypes to insure its transmission despite the dangers of sex. This review mainly focuses on the current knowledge on commitment to sexual development, gametocytogenesis and the evolutionary significance of various aspects of gametocyte biology. It goes further than pure biology to look at the strategies used to improve successful transmission. Although gametocytes are inevitable stages for transmission and provide a potential target to fight malaria, they have received less attention than the pathogenic asexual stages. There is a need for research on gametocytes, which are a fascinating stage, responsible to a large extent for the success of P. falciparum.
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Affiliation(s)
- Arthur M Talman
- Groupe de Recherche sur le Paludisme, Institut Pasteur de Madagascar, B.P.1274 Antananarivo 101, Madagascar
- Department of Biological Sciences, Imperial College London, Exhibition Road, SW7 2AZ London, UK
| | - Olivier Domarle
- Groupe de Recherche sur le Paludisme, Institut Pasteur de Madagascar, B.P.1274 Antananarivo 101, Madagascar
| | - F Ellis McKenzie
- Fogarty International Centre, National Institutes of Health, Bethesda, MD 20892, USA
| | - Frédéric Ariey
- Groupe de Recherche sur le Paludisme, Institut Pasteur de Madagascar, B.P.1274 Antananarivo 101, Madagascar
| | - Vincent Robert
- Groupe de Recherche sur le Paludisme, Institut Pasteur de Madagascar, B.P.1274 Antananarivo 101, Madagascar
- UR 77 Paludisme Afro-tropical, Institut de Recherche pour le Développement, Madagascar
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11
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Li J, Collins WE, Wirtz RA, Rathore D, Lal A, McCutchan TF. Geographic subdivision of the range of the malaria parasite Plasmodium vivax. Emerg Infect Dis 2001; 7:35-42. [PMID: 11266292 PMCID: PMC2631686 DOI: 10.3201/eid0701.010105] [Citation(s) in RCA: 79] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
We examined geographically distinct isolates of Plasmodium vivax and categorized them according to developmental success in Anopheles albimanus. We found that parasites from Central America and Colombia form a group distinct from those of Asia. New World isolates have a distinct chromosomal translocation and an episomal variation in the open reading frame (ORF) 470 DNA sequence that distinguishes them from the other isolates tested. Old World types of P. vivax were introduced into the Americas, and a remnant of this lineage remains in P. simium. It is indistinguishable from Old World P. vivax to the extent determinable by using our encoded markers and the examination of its developmental pattern in mosquitoes. The cohesive characteristics that separate types of P. vivax are predictors of range and potential for transmission and hence require taxonomic distinction.
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Affiliation(s)
- J Li
- National Institutes of Health, Bethesda, Maryland, USA
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12
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Abstract
Malaria and related apicomplexan parasites have two highly conserved organellar genomes: one is of plastid (pl) origin, and the other is mitochondrial (mt). The organization of both organellar DNA molecules from the human malaria parasite Plasmodium falciparum has been determined, and they have been shown to be tightly packed with genes. The 35-kb circular DNA is the smallest known vestigial plastid genome and is presumed to be functional. All but two of its recognized genes are involved with genetic expression: one of the two encodes a member of the clp family of molecular chaperones, and the other encodes a conserved protein of unknown function found both in algal plastids and in eubacterial genomes. The possible evolutionary source and intracellular location of the plDNA are discussed. The 6-kb tandemly repeated mt genome is the smallest known and codes for only three proteins (cytochrome b and two subunits of cytochrome oxidase) as well as two bizarrely fragmented rRNAs. The organization of the mt genome differs somewhat among genera. The mtDNA sequence provides information not otherwise available about the structure of apicomplexan cytochrome b as well as the unusually fragmented rRNAs. The malarial mtDNA has a phage-like replication mechanism and undergoes extensive recombination like the mtDNA of some other lower eukaryotes.
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Affiliation(s)
- R J Wilson
- National Institute for Medical Research, London, United Kingdom.
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13
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Guinet F, Dvorak JA, Fujioka H, Keister DB, Muratova O, Kaslow DC, Aikawa M, Vaidya AB, Wellems TE. A developmental defect in Plasmodium falciparum male gametogenesis. J Biophys Biochem Cytol 1996; 135:269-78. [PMID: 8858179 PMCID: PMC2121010 DOI: 10.1083/jcb.135.1.269] [Citation(s) in RCA: 47] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Asexually replicating populations of Plasmodium parasites, including those from cloned lines, generate both male and female gametes to complete the malaria life cycle through the mosquito. The generation of these sexual forms begins with the induction of gametocytes from haploid asexual stage parasites in the blood of the vertebrate host. The molecular processes that govern the differentiation and development of the sexual forms are largely unknown. Here we describe a defect that affects the development of competent male gametocytes from a mutant clone of P. falciparum (Dd2). Comparison of the Dd2 clone to the predecessor clone from which it was derived (W2'82) shows that the defect is a mutation that arose during the long-term cultivation of asexual stages in vitro. Light and electron microscopic images, and indirect immunofluorescence assays with male-specific anti-alpha-tubulin II antibodies, indicate a global disruption of male development at the gametocyte level with at least a 70-90% reduction in the proportion of mature male gametocytes by the Dd2 clone relative to W2'82. A high prevalence of abnormal gametocyte forms, frequently containing multiple and unusually large vacuoles, is associated with the defect. The reduced production of mature male gametocytes may reflect a problem in processes that commit a gametocyte to male development or a progressive attrition of viable male gametocytes during maturation. The defect is genetically linked to an almost complete absence of male gamete production and of infectivity to mosquitoes. This is the first sex-specific developmental mutation identified and characterized in Plasmodium.
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Affiliation(s)
- F Guinet
- Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland 20892-0425, USA
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14
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Birky CW. Uniparental inheritance of mitochondrial and chloroplast genes: mechanisms and evolution. Proc Natl Acad Sci U S A 1995; 92:11331-8. [PMID: 8524780 PMCID: PMC40394 DOI: 10.1073/pnas.92.25.11331] [Citation(s) in RCA: 515] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
In nearly all eukaryotes, at least some individuals inherit mitochondrial and chloroplast genes from only one parent. There is no single mechanism of uniparental inheritance: organelle gene inheritance is blocked by a variety of mechanisms and at different stages of reproduction in different species. Frequent changes in the pattern of organelle gene inheritance during evolution suggest that it is subject to varying selective pressures. Organelle genes often fail to recombine even when inherited biparentally; consequently, their inheritance is asexual. Sexual reproduction is apparently less important for genes in organelles than for nuclear genes, probably because there are fewer of them. As a result organelle sex can be lost because of selection for special reproductive features such as oogamy or because uniparental inheritance reduces the spread of cytoplasmic parasites and selfish organelle DNA.
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Affiliation(s)
- C W Birky
- Department of Molecular Genetics, Ohio State University, Columbus 43210, USA
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