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Leela N, Prommana P, Kamchonwongpaisan S, Taechalertpaisarn T, Shaw PJ. Antimalarial target vulnerability of the putative Plasmodium falciparum methionine synthase. PeerJ 2024; 12:e16595. [PMID: 38239295 PMCID: PMC10795524 DOI: 10.7717/peerj.16595] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2023] [Accepted: 11/14/2023] [Indexed: 01/22/2024] Open
Abstract
Background Plasmodium falciparum possesses a cobalamin-dependent methionine synthase (MS). MS is putatively encoded by the PF3D7_1233700 gene, which is orthologous and syntenic in Plasmodium. However, its vulnerability as an antimalarial target has not been assessed. Methods We edited the PF3D7_1233700 and PF3D7_0417200 (dihydrofolate reductase-thymidylate synthase, DHFR-TS) genes and obtained transgenic P. falciparum parasites expressing epitope-tagged target proteins under the control of the glmS ribozyme. Conditional loss-of-function mutants were obtained by treating transgenic parasites with glucosamine. Results DHFR-TS, but not MS mutants showed a significant proliferation defect over 96 h, suggesting that P. falciparum MS is not a vulnerable antimalarial target.
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Affiliation(s)
- Nirut Leela
- Department of Microbiology, Faculty of Science, Mahidol University, Bangkok, Bangkok, Thailand
| | - Parichat Prommana
- National Center for Genetic Engineering and Biotechnology (BIOTEC), National Science and Technology Development Agency, Pathum Thani, Thailand
| | - Sumalee Kamchonwongpaisan
- National Center for Genetic Engineering and Biotechnology (BIOTEC), National Science and Technology Development Agency, Pathum Thani, Thailand
| | - Tana Taechalertpaisarn
- Department of Microbiology, Faculty of Science, Mahidol University, Bangkok, Bangkok, Thailand
| | - Philip J. Shaw
- National Center for Genetic Engineering and Biotechnology (BIOTEC), National Science and Technology Development Agency, Pathum Thani, Thailand
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Harris CT, Tong X, Campelo R, Marreiros IM, Vanheer LN, Nahiyaan N, Zuzarte-Luís VA, Deitsch KW, Mota MM, Rhee KY, Kafsack BFC. Sexual differentiation in human malaria parasites is regulated by competition between phospholipid metabolism and histone methylation. Nat Microbiol 2023; 8:1280-1292. [PMID: 37277533 PMCID: PMC11163918 DOI: 10.1038/s41564-023-01396-w] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2022] [Accepted: 04/25/2023] [Indexed: 06/07/2023]
Abstract
For Plasmodium falciparum, the most widespread and virulent malaria parasite that infects humans, persistence depends on continuous asexual replication in red blood cells, while transmission to their mosquito vector requires asexual blood-stage parasites to differentiate into non-replicating gametocytes. This decision is controlled by stochastic derepression of a heterochromatin-silenced locus encoding AP2-G, the master transcription factor of sexual differentiation. The frequency of ap2-g derepression was shown to be responsive to extracellular phospholipid precursors but the mechanism linking these metabolites to epigenetic regulation of ap2-g was unknown. Through a combination of molecular genetics, metabolomics and chromatin profiling, we show that this response is mediated by metabolic competition for the methyl donor S-adenosylmethionine between histone methyltransferases and phosphoethanolamine methyltransferase, a critical enzyme in the parasite's pathway for de novo phosphatidylcholine synthesis. When phosphatidylcholine precursors are scarce, increased consumption of SAM for de novo phosphatidylcholine synthesis impairs maintenance of the histone methylation responsible for silencing ap2-g, increasing the frequency of derepression and sexual differentiation. This provides a key mechanistic link that explains how LysoPC and choline availability can alter the chromatin status of the ap2-g locus controlling sexual differentiation.
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Affiliation(s)
- Chantal T Harris
- Department of Microbiology and Immunology, Weill Cornell Medicine, New York, NY, USA
- Immunology and Microbial Pathogenesis Graduate Program, Weill Cornell Medicine, New York, NY, USA
| | - Xinran Tong
- Department of Microbiology and Immunology, Weill Cornell Medicine, New York, NY, USA
- BCMB Allied Graduate Program, Weill Cornell Medicine, New York, NY, USA
| | - Riward Campelo
- Department of Microbiology and Immunology, Weill Cornell Medicine, New York, NY, USA
| | - Inês M Marreiros
- Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina Universidade de Lisboa, Lisbon, Portugal
- Instituto de Ciências Biomédicas Abel Salazar (ICBAS), Universidade do Porto, Porto, Portugal
| | - Leen N Vanheer
- Department of Microbiology and Immunology, Weill Cornell Medicine, New York, NY, USA
| | - Navid Nahiyaan
- Division of Infectious Diseases, Weill Department of Medicine, Weill Cornell Medicine, New York, NY, USA
| | - Vanessa A Zuzarte-Luís
- Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina Universidade de Lisboa, Lisbon, Portugal
| | - Kirk W Deitsch
- Department of Microbiology and Immunology, Weill Cornell Medicine, New York, NY, USA
| | - Maria M Mota
- Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina Universidade de Lisboa, Lisbon, Portugal
| | - Kyu Y Rhee
- Department of Microbiology and Immunology, Weill Cornell Medicine, New York, NY, USA
- Division of Infectious Diseases, Weill Department of Medicine, Weill Cornell Medicine, New York, NY, USA
| | - Björn F C Kafsack
- Department of Microbiology and Immunology, Weill Cornell Medicine, New York, NY, USA.
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Schneider V, Visone J, Harris C, Florini F, Hadjimichael E, Zhang X, Gross M, Rhee K, Ben Mamoun C, Kafsack B, Deitsch K. The human malaria parasite Plasmodium falciparum can sense environmental changes and respond by antigenic switching. Proc Natl Acad Sci U S A 2023; 120:e2302152120. [PMID: 37068249 PMCID: PMC10151525 DOI: 10.1073/pnas.2302152120] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2023] [Accepted: 03/20/2023] [Indexed: 04/19/2023] Open
Abstract
The primary antigenic and virulence determinant of the human malaria parasite Plasmodium falciparum is a variant surface protein called PfEMP1. Different forms of PfEMP1 are encoded by a multicopy gene family called var, and switching between active genes enables the parasites to evade the antibody response of their human hosts. var gene switching is key for the maintenance of chronic infections; however, what controls switching is unknown, although it has been suggested to occur at a constant frequency with little or no environmental influence. var gene transcription is controlled epigenetically through the activity of histone methyltransferases (HMTs). Studies in model systems have shown that metabolism and epigenetic control of gene expression are linked through the availability of intracellular S-adenosylmethionine (SAM), the principal methyl donor in biological methylation modifications, which can fluctuate based on nutrient availability. To determine whether environmental conditions and changes in metabolism can influence var gene expression, P. falciparum was cultured in media with altered concentrations of nutrients involved in SAM metabolism. We found that conditions that influence lipid metabolism induce var gene switching, indicating that parasites can respond to changes in their environment by altering var gene expression patterns. Genetic modifications that directly modified expression of the enzymes that control SAM levels similarly led to profound changes in var gene expression, confirming that changes in SAM availability modulate var gene switching. These observations directly challenge the paradigm that antigenic variation in P. falciparum follows an intrinsic, programed switching rate, which operates independently of any external stimuli.
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Affiliation(s)
- Victoria M. Schneider
- Department of Microbiology and Immunology, Weill Cornell Medicine, Cornell University, Ithaca, NY14853
- Laboratory of Chemical Biology and Microbial Pathogenesis, Rockefeller University, New York, NY 10065
| | - Joseph E. Visone
- Department of Microbiology and Immunology, Weill Cornell Medicine, Cornell University, Ithaca, NY14853
| | - Chantal T. Harris
- Department of Microbiology and Immunology, Weill Cornell Medicine, Cornell University, Ithaca, NY14853
| | - Francesca Florini
- Department of Microbiology and Immunology, Weill Cornell Medicine, Cornell University, Ithaca, NY14853
| | - Evi Hadjimichael
- Department of Microbiology and Immunology, Weill Cornell Medicine, Cornell University, Ithaca, NY14853
| | - Xu Zhang
- Department of Microbiology and Immunology, Weill Cornell Medicine, Cornell University, Ithaca, NY14853
| | - Mackensie R. Gross
- Department of Microbiology and Immunology, Weill Cornell Medicine, Cornell University, Ithaca, NY14853
| | - Kyu Y. Rhee
- Department of Microbiology and Immunology, Weill Cornell Medicine, Cornell University, Ithaca, NY14853
- Division of Infectious Diseases, Department of Medicine, Weill Cornell Medicine, Cornell University, Ithaca, NY14853
| | - Choukri Ben Mamoun
- Section of Infectious Disease, Department of Microbial Pathogenesis, Yale School of Medicine, Yale University New Haven, CT 06510
| | - Björn F. C. Kafsack
- Department of Microbiology and Immunology, Weill Cornell Medicine, Cornell University, Ithaca, NY14853
| | - Kirk W. Deitsch
- Department of Microbiology and Immunology, Weill Cornell Medicine, Cornell University, Ithaca, NY14853
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Li H, Ji S, Galon EM, Zafar I, Ma Z, Do T, Amer MM, Ma Y, Yamagishi J, Liu M, Xuan X. Identification of three members of the multidomain adhesion CCp family in Babesia gibsoni. Acta Trop 2023; 241:106890. [PMID: 36907290 DOI: 10.1016/j.actatropica.2023.106890] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2023] [Revised: 03/05/2023] [Accepted: 03/07/2023] [Indexed: 03/14/2023]
Abstract
Babesia gibsoni is an intraerythrocytic apicomplexan parasite transmitted by Haemaphysalis longicornis and causes canine babesiosis. Within the tick, the Babesia parasite undergoes sexual conjugation and the sporogony process of its life cycle. To control B. gibsoni infection, prompt and effective treatment of acute infections and curing chronic carriers are urgently needed. Gene disruption of Plasmodium CCps resulted in blocking the transition of sporozoites from the mosquito midgut to the salivary glands, showing that these proteins are potential targets for the development of a transmission-blocking vaccine. In this study, we described the identification and characterization of three members of the CCp family in B. gibsoni, named CCp1, CCp2, and CCp3. The B. gibsoni sexual stages were induced in vitro by exposing parasites to xanthurenic acid (XA), dithiothreitol (DTT), and tris (2-carboxyethyl) phosphine (TCEP) at serial concentrations. Among them, 100 µM XA-exposed and cultured at 27 °C without CO2B. gibsoni presented diverse morphologies, including parasites with long projections, gradually increased free merozoites, and aggregated and round forms, indicative of sexual stage induction. Then, the expression of CCp proteins of induced parasites was confirmed by real-time reverse transcription PCR, immunofluorescence, and western blot. The results showed that BgCCp genes were highly significantly increased at 24 h post-sexual stage induction (p < 0.01). The induced parasites were recognized by anti-CCp mouse antisera and anti-CCp 1, 2, and 3 antibodies weakly reacted with sexual stage proteins of expected molecular weights of 179.4, 169.8, and 140.0 KDa, respectively. Our observations on morphological changes and confirmation of sexual stage protein expression will advance elemental biological research and lay the foundation for the development of transmission-blocking vaccines against canine babesiosis.
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Affiliation(s)
- Hang Li
- National Research Center for Protozoan Diseases, Obihiro University of Agriculture Veterinary Medicine, Inada-cho, Obihiro, Hokkaido 080-8555, Japan
| | - Shengwei Ji
- National Research Center for Protozoan Diseases, Obihiro University of Agriculture Veterinary Medicine, Inada-cho, Obihiro, Hokkaido 080-8555, Japan
| | - Eloiza May Galon
- National Research Center for Protozoan Diseases, Obihiro University of Agriculture Veterinary Medicine, Inada-cho, Obihiro, Hokkaido 080-8555, Japan
| | - Iqra Zafar
- National Research Center for Protozoan Diseases, Obihiro University of Agriculture Veterinary Medicine, Inada-cho, Obihiro, Hokkaido 080-8555, Japan
| | - Zhuowei Ma
- National Research Center for Protozoan Diseases, Obihiro University of Agriculture Veterinary Medicine, Inada-cho, Obihiro, Hokkaido 080-8555, Japan
| | - Thom Do
- National Research Center for Protozoan Diseases, Obihiro University of Agriculture Veterinary Medicine, Inada-cho, Obihiro, Hokkaido 080-8555, Japan
| | - Moaz M Amer
- National Research Center for Protozoan Diseases, Obihiro University of Agriculture Veterinary Medicine, Inada-cho, Obihiro, Hokkaido 080-8555, Japan
| | - Yihong Ma
- National Research Center for Protozoan Diseases, Obihiro University of Agriculture Veterinary Medicine, Inada-cho, Obihiro, Hokkaido 080-8555, Japan
| | - Junya Yamagishi
- Division of Collaboration and Education, International Institute for Zoonosis Control, Hokkaido University, Sapporo 001-0020, Japan
| | - Mingming Liu
- School of Basic Medicine, Hubei University of Arts and Science, Xiangyang 441053, China.
| | - Xuenan Xuan
- National Research Center for Protozoan Diseases, Obihiro University of Agriculture Veterinary Medicine, Inada-cho, Obihiro, Hokkaido 080-8555, Japan.
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Beri D, Singh M, Rodriguez M, Goyal N, Rasquinha G, Liu Y, An X, Yazdanbakhsh K, Lobo CA. Global Metabolomic Profiling of Host Red Blood Cells Infected with Babesia divergens Reveals Novel Antiparasitic Target Pathways. Microbiol Spectr 2023; 11:e0468822. [PMID: 36786651 PMCID: PMC10100774 DOI: 10.1128/spectrum.04688-22] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2022] [Accepted: 01/27/2023] [Indexed: 02/15/2023] Open
Abstract
Babesia divergens is an apicomplexan parasite that infects human red blood cells (RBCs), initiating cycles of invasion, replication, and egress, resulting in extensive metabolic modification of the host cells. Babesia is an auxotroph for most of the nutrients required to sustain these cycles. There are currently limited studies on the biochemical pathways that support these critical processes, necessitating the high-resolution global metabolomics approach described here to uncover the metabolic interactions between parasite and host RBC. Our results reveal an extensive parasite-mediated modulation of RBC metabolite levels of all classes, including lipids, amino acids, carbohydrates, and nucleotides, with numerous metabolic species varying in proportion to the level of infection. Many of these molecules are scavenged from the host RBCs. This is in accord with the needs of a rapidly proliferating parasite with limited biosynthetic capabilities. Probing these pathways in depth, we used growth inhibition assays to quantitate parasite susceptibility to drugs targeting these pathways and stimulated emission depletion (STED) microscopy to obtain high-resolution images of drug-treated parasites to correlate changes in morphology with specific metabolic blocks in order to validate the data generated by the untargeted metabolomics platform. Thus, interruption of cholesterol scavenging from the host cell led to premature parasite egress, while chemical targeting of the hydrolysis of acyl glycerides led to the buildup of malformed parasites that could not successfully egress. This is the first report detailing the global metabolomic profile of the B. divergens-infected RBC. Besides deciphering diverse aspects of the host-parasite relationship, our results can be exploited by others to uncover further drug targets in the host-parasite biochemical network. IMPORTANCE Human babesiosis is caused by apicomplexan parasites of the Babesia genus and is associated with transfusion-transmitted illness and relapsing disease in immunosuppressed populations. Through its continuous cycles of invasion, proliferation, and egress, B. divergens radically changes the metabolic environment of the host red blood cell, allowing us opportunities to study potential chemical vulnerabilities that can be targeted by drugs. This is the first global metabolomic profiling of Babesia-infected human red blood cells, and our analysis revealed perturbation in all biomolecular classes at levels proportional to the level of infection. In particular, lipids and energy flux pathways in the host cell were altered by infection. We validated the changes in key metabolic pathways by performing inhibition assays accompanied by high-resolution microscopy. Overall, this global metabolomics analysis of Babesia-infected red blood cells has helped to uncover novel aspects of parasite biology and identified potential biochemical pathways that can be targeted for chemotherapeutic intervention.
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Affiliation(s)
- Divya Beri
- Department of Blood-Borne Parasites, Lindsley F. Kimball Research Institute, New York Blood Center, New York, New York, USA
| | - Manpreet Singh
- Department of Blood-Borne Parasites, Lindsley F. Kimball Research Institute, New York Blood Center, New York, New York, USA
| | - Marilis Rodriguez
- Department of Blood-Borne Parasites, Lindsley F. Kimball Research Institute, New York Blood Center, New York, New York, USA
| | - Naman Goyal
- Department of Blood-Borne Parasites, Lindsley F. Kimball Research Institute, New York Blood Center, New York, New York, USA
| | | | - Yunfeng Liu
- Department of Complement Biology, Lindsley F. Kimball Research Institute, New York Blood Center, New York, New York, USA
| | - Xiuli An
- Department of Membrane Biology, Lindsley F. Kimball Research Institute, New York Blood Center, New York, New York, USA
| | - Karina Yazdanbakhsh
- Department of Complement Biology, Lindsley F. Kimball Research Institute, New York Blood Center, New York, New York, USA
| | - Cheryl A. Lobo
- Department of Blood-Borne Parasites, Lindsley F. Kimball Research Institute, New York Blood Center, New York, New York, USA
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Cruz Camacho A, Kiper E, Oren S, Zaharoni N, Nir N, Soffer N, Noy Y, Ben David B, Rivkin A, Rotkopf R, Michael D, Carvalho TG, Regev-Rudzki N. High-throughput analysis of the transcriptional patterns of sexual genes in malaria. Parasit Vectors 2023; 16:14. [PMID: 36639683 PMCID: PMC9838061 DOI: 10.1186/s13071-022-05624-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2022] [Accepted: 12/17/2022] [Indexed: 01/15/2023] Open
Abstract
BACKGROUND Plasmodium falciparum (Pf) is the leading protozoan causing malaria, the most devastating parasitic disease. To ensure transmission, a small subset of Pf parasites differentiate into the sexual forms (gametocytes). Since the abundance of these essential parasitic forms is extremely low within the human host, little is currently known about the molecular regulation of their sexual differentiation, highlighting the need to develop tools to investigate Pf gene expression during this fundamental mechanism. METHODS We developed a high-throughput quantitative Reverse-Transcription PCR (RT-qPCR) platform to robustly monitor Pf transcriptional patterns, in particular, systematically profiling the transcriptional pattern of a large panel of gametocyte-related genes (GRG). Initially, we evaluated the technical performance of the systematic RT-qPCR platform to ensure it complies with the accepted quality standards for: (i) RNA extraction, (ii) cDNA synthesis and (iii) evaluation of gene expression through RT-qPCR. We then used this approach to monitor alterations in gene expression of a panel of GRG upon treatment with gametocytogenesis regulators. RESULTS We thoroughly elucidated GRG expression profiles under treatment with the antimalarial drug dihydroartemisinin (DHA) or the metabolite choline over the course of a Pf blood cycle (48 h). We demonstrate that both significantly alter the expression pattern of PfAP2-G, the gametocytogenesis master regulator. However, they also markedly modify the developmental rate of the parasites and thus might bias the mRNA expression. Additionally, we screened the effect of the metabolites lactate and kynurenic acid, abundant in severe malaria, as potential regulators of gametocytogenesis. CONCLUSIONS Our data demonstrate that the high-throughput RT-qPCR method enables studying the immediate transcriptional response initiating gametocytogenesis of the parasites from a very low volume of malaria-infected RBC samples. The obtained data expand the current knowledge of the initial alterations in mRNA profiles of GRG upon treatment with reported regulators. In addition, using this method emphasizes that asexual parasite stage composition is a crucial element that must be considered when interpreting changes in GRG expression by RT-qPCR, specifically when screening for novel compounds that could regulate Pf sexual differentiation.
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Affiliation(s)
- Abel Cruz Camacho
- grid.13992.300000 0004 0604 7563Faculty of Biochemistry, Department of Biomolecular Sciences, Weizmann Institute of Science, 7610001 Rehovot, Israel
| | - Edo Kiper
- grid.13992.300000 0004 0604 7563Faculty of Biochemistry, Department of Biomolecular Sciences, Weizmann Institute of Science, 7610001 Rehovot, Israel
| | - Sonia Oren
- grid.13992.300000 0004 0604 7563Faculty of Biochemistry, Department of Biomolecular Sciences, Weizmann Institute of Science, 7610001 Rehovot, Israel
| | - Nir Zaharoni
- grid.13992.300000 0004 0604 7563Faculty of Biochemistry, Department of Biomolecular Sciences, Weizmann Institute of Science, 7610001 Rehovot, Israel
| | - Netta Nir
- grid.13992.300000 0004 0604 7563Faculty of Biochemistry, Department of Biomolecular Sciences, Weizmann Institute of Science, 7610001 Rehovot, Israel
| | - Noam Soffer
- grid.13992.300000 0004 0604 7563Faculty of Biochemistry, Department of Biomolecular Sciences, Weizmann Institute of Science, 7610001 Rehovot, Israel
| | - Yael Noy
- grid.13992.300000 0004 0604 7563Faculty of Biochemistry, Department of Biomolecular Sciences, Weizmann Institute of Science, 7610001 Rehovot, Israel
| | - Bar Ben David
- grid.13992.300000 0004 0604 7563Faculty of Biochemistry, Department of Biomolecular Sciences, Weizmann Institute of Science, 7610001 Rehovot, Israel
| | - Anna Rivkin
- grid.13992.300000 0004 0604 7563Faculty of Biochemistry, Department of Biomolecular Sciences, Weizmann Institute of Science, 7610001 Rehovot, Israel
| | - Ron Rotkopf
- grid.13992.300000 0004 0604 7563Department of Life Sciences Core Facilities, Weizmann Institute of Science, 7610001 Rehovot, Israel
| | - Dan Michael
- grid.13992.300000 0004 0604 7563Feinberg Graduate School, Weizmann Institute of Science, 7610001 Rehovot, Israel
| | - Teresa G. Carvalho
- grid.1018.80000 0001 2342 0938Department of Microbiology, Anatomy, Physiology and Pharmacology, La Trobe University, Melbourne, VIC 3086 Australia
| | - Neta Regev-Rudzki
- grid.13992.300000 0004 0604 7563Faculty of Biochemistry, Department of Biomolecular Sciences, Weizmann Institute of Science, 7610001 Rehovot, Israel
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Stewart LB, Freville A, Voss TS, Baker DA, Awandare GA, Conway DJ. Plasmodium falciparum Sexual Commitment Rate Variation among Clinical Isolates and Diverse Laboratory-Adapted Lines. Microbiol Spectr 2022; 10:e0223422. [PMID: 36409095 PMCID: PMC9769538 DOI: 10.1128/spectrum.02234-22] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2022] [Accepted: 10/20/2022] [Indexed: 11/23/2022] Open
Abstract
Asexual blood-stage malaria parasites must produce sexual progeny to infect mosquitoes. It is important to understand the scope and causes of intraspecific variation in sexual commitment rates, particularly for the major human parasite P. falciparum. First, two alternative assay methods of measuring sexual commitment were compared to test a genetically modified P. falciparum line with elevated commitment rates inducible by overexpression of GDV1. The methods yielded correlated measurements with higher sensitivity and precision being achieved by one employing detection of the early gametocyte differentiation marker Pfs16. Thus, this was used to survey a diverse range of parasite lines and test each in multiple biological replicate assays in a serum-free medium supplemented with Albumax. There were differences among six recent clinical isolates from Ghana in their mean rates of sexual commitment per cycle, ranging from 3.3% to 12.2%. Among 13 diverse long-term laboratory-adapted lines, mean sexual commitment rates for most ranged from 4.7% to 13.4%, a few had lower rates with means from 0.3 to 1.6%, and one with a nonfunctional ap2-g gene always showed zero commitment. Among a subset of lines tested for the effects of exogenous choline to suppress commitment, there were significant differences. As expected, there was no effect in a line that had lost the gdv1 gene and that had generally low commitment, whereas the others showed quantitatively variable but significant responses to choline, suggesting potential trait variation. The results indicated the value of performing multiple replicate assays for understanding the variation of this key reproductive trait that likely affects transmission. IMPORTANCE Only sexual-stage malaria parasites are transmitted from human blood to mosquitoes. Thus, it is vital to understand variations in sexual commitment rates because these may be modifiable or susceptible to blocking. Two different methods of commitment rate measurement were first compared, demonstrating higher sensitivity and precision by the detection of an early differentiation marker, which was subsequently used to survey diverse lines. Clinical isolates from Ghana showed significant variation in mean per-cycle commitment rates and variation among biological replicates. Laboratory-adapted lines of diverse origins had a wider range with most being within the range observed for the clinical isolates, while a minority consistently had lower or zero rates. There was quantitative variation in the effects when adding choline to suppress commitment, indicating differing responsiveness of parasites to this environmental modification. Performing multiple assay replicates and comparisons of diverse isolates was important to understand this trait and its potential effects on transmission.
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Affiliation(s)
- Lindsay B. Stewart
- Department of Infection Biology, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Aline Freville
- Department of Infection Biology, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Till S. Voss
- Department of Medical Parasitology and Infection Biology, Swiss Tropical and Public Health Institute, University of Basel, Basal, Switzerland
| | - David A. Baker
- Department of Infection Biology, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Gordon A. Awandare
- West African Centre for Cell Biology of Infectious Pathogens (WACCBIP), Department of Biochemistry, Cell and Molecular Biology, University of Ghana, Accra, Ghana
| | - David J. Conway
- Department of Infection Biology, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, United Kingdom
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Haag M, Kehrer J, Sanchez CP, Deponte M, Lanzer M. Physiological jump in erythrocyte redox potential during Plasmodium falciparum development occurs independent of the sickle cell trait. Redox Biol 2022; 58:102536. [DOI: 10.1016/j.redox.2022.102536] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2022] [Revised: 10/26/2022] [Accepted: 11/08/2022] [Indexed: 11/11/2022] Open
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9
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Beri D, Rodriguez M, Singh M, Liu Y, Rasquinha G, An X, Yazdanbakhsh K, Lobo CA. Identification and characterization of extracellular vesicles from red cells infected with Babesia divergens and Babesia microti. Front Cell Infect Microbiol 2022; 12:962944. [PMID: 36275032 PMCID: PMC9585353 DOI: 10.3389/fcimb.2022.962944] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2022] [Accepted: 09/05/2022] [Indexed: 11/21/2022] Open
Abstract
Babesiosis is a zoonosis and an important blood-borne human parasitic infection that has gained attention because of its growing infection rate in humans by transfer from animal reservoirs. Babesia represents a potential threat to the blood supply because asymptomatic infections in man are common, and blood from such donors can cause severe disease in certain recipients. Extracellular vesicles (EVs) are vesicles released by cells that contain a complex mixture of proteins, lipids, glycans, and genetic information that have been shown to play important roles in disease pathogenesis and susceptibility, as well as cell–cell communication and immune responses. In this article, we report on the identification and characterization of EVs released from red blood cells (RBCs) infected by two major human Babesia species—Babesia divergens from in vitro culture and those from an in vivo B. microti mouse infection. Using nanoparticle tracking analysis, we show that there is a range of vesicle sizes from 30 to 1,000 nm, emanating from the Babesia-infected RBC. The study of these EVs in the context of hemoparasite infection is complicated by the fact that both the parasite and the host RBC make and release vesicles into the extracellular environment. However, the EV frequency is 2- to 10-fold higher in Babesia-infected RBCs than uninfected RBCs, depending on levels of parasitemia. Using parasite-specific markers, we were able to show that ~50%–60% of all EVs contained parasite-specific markers on their surface and thus may represent the specific proportion of EVs released by infected RBCs within the EV population. Western blot analysis on purified EVs from both in vivo and in vitro infections revealed several parasite proteins that were targets of the host immune response. In addition, microRNA analysis showed that infected RBC EVs have different microRNA signature from uninfected RBC EVs, indicating a potential role as disease biomarkers. Finally, EVs were internalized by other RBCs in culture, implicating a potential role for these vesicles in cellular communication. Overall, our study points to the multiple functional implications of EVs in Babesia–host interactions and support the potential that EVs have as agents in disease pathogenesis.
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Affiliation(s)
- Divya Beri
- Department of Blood-Borne Parasites, Lindsley F. Kimball Research Institute, New York Blood Center, New York, NY, United States
| | - Marilis Rodriguez
- Department of Blood-Borne Parasites, Lindsley F. Kimball Research Institute, New York Blood Center, New York, NY, United States
| | - Manpreet Singh
- Department of Blood-Borne Parasites, Lindsley F. Kimball Research Institute, New York Blood Center, New York, NY, United States
| | - Yunfeng Liu
- Department of Complement Biology, Lindsley F. Kimball Research Institute, New York Blood Center, New York, NY, United States
| | - Giselle Rasquinha
- Department of Biology, Georgetown University, Washington, DC, United States
| | - Xiuli An
- Department of Membrane Biology, Lindsley F. Kimball Research Institute, New York Blood Center, New York, NY, United States
| | - Karina Yazdanbakhsh
- Department of Complement Biology, Lindsley F. Kimball Research Institute, New York Blood Center, New York, NY, United States
| | - Cheryl A. Lobo
- Department of Blood-Borne Parasites, Lindsley F. Kimball Research Institute, New York Blood Center, New York, NY, United States
- *Correspondence: Cheryl A. Lobo,
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10
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Recent metabolomic developments for antimalarial drug discovery. Parasitol Res 2022; 121:3351-3380. [PMID: 36194273 DOI: 10.1007/s00436-022-07673-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2022] [Accepted: 09/14/2022] [Indexed: 10/10/2022]
Abstract
Malaria is a parasitic disease that remains a global health issue, responsible for a significant death and morbidity toll. Various factors have impacted the use and delayed the development of antimalarial therapies, such as the associated financial cost and parasitic resistance. In order to discover new drugs and validate parasitic targets, a powerful omics tool, metabolomics, emerged as a reliable approach. However, as a fairly recent method in malaria, new findings are timely and original practices emerge frequently. This review aims to discuss recent research towards the development of new metabolomic methods in the context of uncovering antiplasmodial mechanisms of action in vitro and to point out innovative metabolic pathways that can revitalize the antimalarial pipeline.
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11
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Teng PY, Choi J, Yadav S, Tompkins YH, Kim WK. Effects of low-crude protein diets supplemented with arginine, glutamine, threonine, and methionine on regulating nutrient absorption, intestinal health, and growth performance of Eimeria-infected chickens. Poult Sci 2021; 100:101427. [PMID: 34551373 PMCID: PMC8463775 DOI: 10.1016/j.psj.2021.101427] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2021] [Revised: 07/16/2021] [Accepted: 07/21/2021] [Indexed: 11/29/2022] Open
Abstract
The study was conducted to evaluate the effects of low crude protein diets supplemented with arginine, glutamine, methionine, and/or threonine on apparent ileal digestibility of amino acids, intestinal morphology, intestinal permeability, gene expression of nutrient transporters, and tight junction proteins of broiler chickens challenged with mixed Eimeria spp. A total of five hundred seventy-six, 12-day-old male broiler chickens were allocated into 8 treatments, and 6 replicate cages of 12 chickens per cage. This experiment included a nonchallenged control (NC) fed regular corn-soybean meal-based diet (Regular diet, 19% crude protein), an Eimeria-challenged control (CC) fed Regular diet, an Eimeria challenge group fed low-crude protein diet (LCP, 16% crude protein), 4 Eimeria challenge groups fed low-crude protein diet supplemented with 0.75% arginine, glutamine, methionine, and threonine, respectively (ARG, GLN, MET, and THR), and an Eimeria challenge group fed low-crude protein diet with 0.75% supplemented arginine, glutamine, methionine, and threonine collectively as a combination group (COMB). On d 14, birds in the challenge groups were gavaged with a mixed Eimeria spp. solution containing 12,500 oocysts of E. maxima, 12,500 oocysts of E. tenella, and 62,500 oocysts of E. acervulina. The results showed that the Eimeria challenge reduced overall growth performance, but the LCP had no adverse impacts on intestinal health and growth of Eimeria-infected birds compared to the CC. Additionally, supplementation of crystalline arginine, glutamine, methionine, and threonine improved the apparent ileal digestibility of these specific amino acids on 6 dpi. Moreover, the THR treatment increased villus height in the duodenum. The ARG treatment decreased intestinal permeability and gene expression of amino acid transporters, whereas the GLN and THR treatments both reversed adverse effects of coccidiosis on gene expression of tight junction protein (claudin 1). However, the MET and COMB treatments exacerbated infection severity of coccidiosis. In summary, adding 0.75% of arginine, glutamine, or threonine in a low crude protein diet can improve the intestinal health of birds challenged with a mild coccidia infection.
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Affiliation(s)
- Po-Yun Teng
- Department of Poultry Science, University of Georgia, Athens, GA, USA
| | - Janghan Choi
- Department of Poultry Science, University of Georgia, Athens, GA, USA
| | - Sudhir Yadav
- Department of Poultry Science, University of Georgia, Athens, GA, USA
| | - Y H Tompkins
- Department of Poultry Science, University of Georgia, Athens, GA, USA
| | - Woo Kyun Kim
- Department of Poultry Science, University of Georgia, Athens, GA, USA.
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12
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Neveu G, Beri D, Kafsack BF. Metabolic regulation of sexual commitment in Plasmodium falciparum. Curr Opin Microbiol 2020; 58:93-98. [PMID: 33053503 DOI: 10.1016/j.mib.2020.09.004] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2020] [Accepted: 09/08/2020] [Indexed: 11/29/2022]
Abstract
For malaria parasites regulating sexual commitment, the frequency with which asexual bloodstream forms differentiate into non-replicative male and female gametocytes, is critical because asexual replication is required to maintain a persistent infection of the human host while gametocytes are essential for infection of the mosquito vector and transmission. Here, we describe recent advances in understanding of the regulatory mechanisms controlling this key developmental decision. These include new insights into the mechanistic roles of the transcriptional master switch AP2-G and the epigenetic modulator GDV1, as well as the identification of defined metabolic signals that modulate their activity. Many of these metabolites are linked to parasite phospholipid biogenesis and we propose a model linking this pathway to the epigenetic regulation underlying sexual commitment in P. falciparum.
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Affiliation(s)
- Gaelle Neveu
- Department of Microbiology and Immunology, Weill Cornell Medicine, New York, NY, 10065 USA
| | - Divya Beri
- Department of Microbiology and Immunology, Weill Cornell Medicine, New York, NY, 10065 USA
| | - Björn Fc Kafsack
- Department of Microbiology and Immunology, Weill Cornell Medicine, New York, NY, 10065 USA.
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13
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Joice Cordy R. Mining the Human Host Metabolome Toward an Improved Understanding of Malaria Transmission. Front Microbiol 2020; 11:164. [PMID: 32117175 PMCID: PMC7033509 DOI: 10.3389/fmicb.2020.00164] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2019] [Accepted: 01/23/2020] [Indexed: 12/27/2022] Open
Abstract
The big data movement has led to major advances in our ability to assess vast and complex datasets related to the host and parasite during malaria infection. While host and parasite genomics and transcriptomics are often the focus of many computational efforts in malaria research, metabolomics represents another big data type that has great promise for aiding our understanding of complex host-parasite interactions that lead to the transmission of malaria. Recent analyses of the complement of metabolites present in human blood, skin and breath suggest that host metabolites play a critical role in the transmission cycle of malaria. Volatile compounds released through breath and skin serve as attractants to mosquitoes, with malaria-infected hosts appearing to have unique profiles that further increase host attractiveness. Inside the host, fluctuations in the levels of certain metabolites in blood may trigger increased production of transmission-competent sexual stages (gametocytes), setting the stage for enhanced transmission of malaria from human to mosquito. Together, these recent discoveries suggest that metabolites of human blood, skin and breath play critical roles in malaria transmission. This review discusses recent advances in this area, with a focus on metabolites that have been identified to play a role in malaria transmission and methods that may lead to an improved understanding of malaria transmission.
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Affiliation(s)
- Regina Joice Cordy
- Department of Biology, Wake Forest University, Winston-Salem, NC, United States.,Department of Microbiology and Immunology, Wake Forest School of Medicine, Winston-Salem, NC, United States
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14
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ApiAP2 Transcription Factors in Apicomplexan Parasites. Pathogens 2019; 8:pathogens8020047. [PMID: 30959972 PMCID: PMC6631176 DOI: 10.3390/pathogens8020047] [Citation(s) in RCA: 57] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2019] [Revised: 03/26/2019] [Accepted: 03/28/2019] [Indexed: 12/26/2022] Open
Abstract
Apicomplexan parasites are protozoan organisms that are characterised by complex life cycles and they include medically important species, such as the malaria parasite Plasmodium and the causative agents of toxoplasmosis (Toxoplasma gondii) and cryptosporidiosis (Cryptosporidium spp.). Apicomplexan parasites can infect one or more hosts, in which they differentiate into several morphologically and metabolically distinct life cycle stages. These developmental transitions rely on changes in gene expression. In the last few years, the important roles of different members of the ApiAP2 transcription factor family in regulating life cycle transitions and other aspects of parasite biology have become apparent. Here, we review recent progress in our understanding of the different members of the ApiAP2 transcription factor family in apicomplexan parasites.
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15
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Beri D, Ramdani G, Balan B, Gadara D, Poojary M, Momeux L, Tatu U, Langsley G. Insights into physiological roles of unique metabolites released from Plasmodium-infected RBCs and their potential as clinical biomarkers for malaria. Sci Rep 2019; 9:2875. [PMID: 30814599 PMCID: PMC6393545 DOI: 10.1038/s41598-018-37816-9] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2018] [Accepted: 12/12/2018] [Indexed: 11/10/2022] Open
Abstract
Plasmodium sp. are obligate intracellular parasites that derive most of their nutrients from their host meaning the metabolic circuitry of both are intricately linked. We employed untargeted, global mass spectrometry to identify metabolites present in the culture supernatants of P. falciparum-infected red blood cells synchronized at ring, trophozoite and schizont developmental stages. This revealed a temporal regulation in release of a distinct set of metabolites compared with supernatants of non-infected red blood cells. Of the distinct metabolites we identified pipecolic acid to be abundantly present in parasite lysate, infected red blood cells and infected culture supernatant. Further, we performed targeted metabolomics to quantify pipecolic acid concentrations in both the supernatants of red blood cells infected with P. falciparum, as well as in the plasma and infected RBCs of P. berghei-infected mice. Measurable and significant hyperpipecolatemia suggest that pipecolic acid has the potential to be a diagnostic marker for malaria.
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Affiliation(s)
- Divya Beri
- Department of Biochemistry, Indian Institute of Science, Bangalore, 560012, India
| | - Ghania Ramdani
- Inserm U1016, Cnrs UMR8104, Cochin Institute, Paris, 75014, France.,Laboratoire de Biologie Cellulaire Comparative des Apicomplexes, Faculté de Médecine, Université Paris Descartes - Sorbonne Paris Cité, Paris, France
| | - Balu Balan
- Department of Biochemistry, Indian Institute of Science, Bangalore, 560012, India
| | - Darshak Gadara
- Department of Biochemistry, Indian Institute of Science, Bangalore, 560012, India
| | - Mukta Poojary
- Department of Biochemistry, Indian Institute of Science, Bangalore, 560012, India
| | - Laurence Momeux
- Inserm U1016, Cnrs UMR8104, Cochin Institute, Paris, 75014, France.,Laboratoire de Biologie Cellulaire Comparative des Apicomplexes, Faculté de Médecine, Université Paris Descartes - Sorbonne Paris Cité, Paris, France
| | - Utpal Tatu
- Department of Biochemistry, Indian Institute of Science, Bangalore, 560012, India.
| | - Gordon Langsley
- Inserm U1016, Cnrs UMR8104, Cochin Institute, Paris, 75014, France. .,Laboratoire de Biologie Cellulaire Comparative des Apicomplexes, Faculté de Médecine, Université Paris Descartes - Sorbonne Paris Cité, Paris, France.
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16
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Breuer M, Earnest TM, Merryman C, Wise KS, Sun L, Lynott MR, Hutchison CA, Smith HO, Lapek JD, Gonzalez DJ, de Crécy-Lagard V, Haas D, Hanson AD, Labhsetwar P, Glass JI, Luthey-Schulten Z. Essential metabolism for a minimal cell. eLife 2019; 8:36842. [PMID: 30657448 PMCID: PMC6609329 DOI: 10.7554/elife.36842] [Citation(s) in RCA: 78] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2018] [Accepted: 01/17/2019] [Indexed: 11/29/2022] Open
Abstract
JCVI-syn3A, a robust minimal cell with a 543 kbp genome and 493 genes, provides a versatile platform to study the basics of life. Using the vast amount of experimental information available on its precursor, Mycoplasma mycoides capri, we assembled a near-complete metabolic network with 98% of enzymatic reactions supported by annotation or experiment. The model agrees well with genome-scale in vivo transposon mutagenesis experiments, showing a Matthews correlation coefficient of 0.59. The genes in the reconstruction have a high in vivo essentiality or quasi-essentiality of 92% (68% essential), compared to 79% in silico essentiality. This coherent model of the minimal metabolism in JCVI-syn3A at the same time also points toward specific open questions regarding the minimal genome of JCVI-syn3A, which still contains many genes of generic or completely unclear function. In particular, the model, its comparison to in vivo essentiality and proteomics data yield specific hypotheses on gene functions and metabolic capabilities; and provide suggestions for several further gene removals. In this way, the model and its accompanying data guide future investigations of the minimal cell. Finally, the identification of 30 essential genes with unclear function will motivate the search for new biological mechanisms beyond metabolism. One way that researchers can test whether they understand a biological system is to see if they can accurately recreate it as a computer model. The more they learn about living things, the more the researchers can improve their models and the closer the models become to simulating the original. In this approach, it is best to start by trying to model a simple system. Biologists have previously succeeded in creating ‘minimal bacterial cells’. These synthetic cells contain fewer genes than almost all other living things and they are believed to be among the simplest possible forms of life that can grow on their own. The minimal cells can produce all the chemicals that they need to survive – in other words, they have a metabolism. Accurately recreating one of these cells in a computer is a key first step towards simulating a complete living system. Breuer et al. have developed a computer model to simulate the network of the biochemical reactions going on inside a minimal cell with just 493 genes. By altering the parameters of their model and comparing the results to experimental data, Breuer et al. explored the accuracy of their model. Overall, the model reproduces experimental results, but it is not yet perfect. The differences between the model and the experiments suggest new questions and tests that could advance our understanding of biology. In particular, Breuer et al. identified 30 genes that are essential for life in these cells but that currently have no known purpose. Continuing to develop and expand models like these to reproduce more complex living systems provides a tool to test current knowledge of biology. These models may become so advanced that they could predict how living things will respond to changing situations. This would allow scientists to test ideas sooner and make much faster progress in understanding life on Earth. Ultimately, these models could one day help to accelerate medical and industrial processes to save lives and enhance productivity.
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Affiliation(s)
- Marian Breuer
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, United States
| | - Tyler M Earnest
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, United States
| | | | - Kim S Wise
- J Craig Venter Institute, La Jolla, United States
| | - Lijie Sun
- J Craig Venter Institute, La Jolla, United States
| | | | | | | | - John D Lapek
- Department of Pharmacology and School of Pharmacy, University of California at San Diego, La Jolla, United States
| | - David J Gonzalez
- Department of Pharmacology and School of Pharmacy, University of California at San Diego, La Jolla, United States
| | - Valérie de Crécy-Lagard
- Department of Microbiology and Cell Science, University of Florida, Gainesville, United States
| | - Drago Haas
- Department of Microbiology and Cell Science, University of Florida, Gainesville, United States
| | - Andrew D Hanson
- Horticultural Sciences Department, University of Florida, Gainesville, United States
| | - Piyush Labhsetwar
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, United States
| | - John I Glass
- J Craig Venter Institute, La Jolla, United States
| | - Zaida Luthey-Schulten
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, United States
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17
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Bohaliga GAR, Johnson WC, Taus NS, Hussein HE, Bastos RG, Suarez CE, O’Connor R, Ueti MW. Identification of a putative methyltransferase gene of Babesia bigemina as a novel molecular biomarker uniquely expressed in parasite tick stages. Parasit Vectors 2018; 11:480. [PMID: 30143025 PMCID: PMC6109354 DOI: 10.1186/s13071-018-3052-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2018] [Accepted: 08/06/2018] [Indexed: 01/24/2023] Open
Abstract
BACKGROUND Bovine babesiosis is caused by apicomplexan pathogens of the genus Babesia such as B. bigemina and B. bovis. These tick-borne pathogens have a complex life-cycle involving asexual multiplication in vertebrate hosts and sexual reproduction in invertebrate vectors. In the tick midgut, extracellular Babesia parasites transform into gametes that fuse to form zygotes. Understanding the mechanisms that underlie formation of extracellular Babesia tick stages is an important step towards developing control strategies for preventing tick infection and subsequent parasite transmission. RESULTS We induced B. bigemina sexual stages in vitro by exposing parasites to Tris 2-carboxyethyl phosphine (TCEP). Subsequently, we identified a novel putative methyltransferase gene (BBBOND_0204030) that is expressed uniquely in all B. bigemina tick stages but not in blood stages. In vitro TCEP-exposed B. bigemina presented diverse morphology including parasites with long projections, round forms and clusters of round forms indicative of sexual stage induction. We confirmed the development of sexual stages by detecting upregulation of previously defined B. bigemina sexual stage marker genes, ccp2 and 3, and their respective protein expression in TCEP-induced B. bigemina cultures. Next, transcription analysis of in vitro TCEP-induced B. bigemina culture based on an in silico derived list of homologs of Plasmodium falciparum gamete-specific genes demonstrated differential expression of the gene BBBOND_0204030 in induced cells. Further examination of ex vivo infected ticks demonstrated that BBBOND_0204030 is transcribed by multiple stages of B. bigemina during parasite development in tick midgut, ovary and hemolymph. Interestingly, ex vivo results confirmed our in vitro observation that blood stages of B. bigemina do not express BBBOND_0204030 and validated the in vitro system of inducing sexual stages. CONCLUSIONS Herein we describe the identification of a B. bigemina gene transcribed exclusively by parasites infecting ticks using a novel method of inducing B. bigemina sexual stages in vitro. We propose that this gene can be used as a marker for parasite development within the tick vector. Together, these tools will facilitate our understanding of parasite-tick interactions, the identification of novel vaccine targets and, consequently, the development of additional strategies to control bovine babesiosis.
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Affiliation(s)
- Gamila A. R. Bohaliga
- Program in Vector-borne Diseases, Department of Veterinary Microbiology and Pathology, Washington State University, Pullman, Washington, 99164 USA
| | - Wendell C. Johnson
- Animal Diseases Research Unit, USDA-ARS, Pullman, Washington, 99164-6630 USA
| | - Naomi S. Taus
- Program in Vector-borne Diseases, Department of Veterinary Microbiology and Pathology, Washington State University, Pullman, Washington, 99164 USA
- Animal Diseases Research Unit, USDA-ARS, Pullman, Washington, 99164-6630 USA
| | - Hala E. Hussein
- Program in Vector-borne Diseases, Department of Veterinary Microbiology and Pathology, Washington State University, Pullman, Washington, 99164 USA
- Department of Entomology, Faculty of Science, Cairo University, Giza, 12613 Egypt
| | - Reginaldo G. Bastos
- Program in Vector-borne Diseases, Department of Veterinary Microbiology and Pathology, Washington State University, Pullman, Washington, 99164 USA
| | - Carlos E. Suarez
- Animal Diseases Research Unit, USDA-ARS, Pullman, Washington, 99164-6630 USA
| | - Roberta O’Connor
- Program in Vector-borne Diseases, Department of Veterinary Microbiology and Pathology, Washington State University, Pullman, Washington, 99164 USA
| | - Massaro W. Ueti
- Program in Vector-borne Diseases, Department of Veterinary Microbiology and Pathology, Washington State University, Pullman, Washington, 99164 USA
- Animal Diseases Research Unit, USDA-ARS, Pullman, Washington, 99164-6630 USA
- The Paul G. Allen School for Global Animal Health, Washington State University, Pullman, Washington, 99164-70403 USA
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18
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Abstract
Malaria is the major cause of mortality and morbidity in tropical countries. The causative agent, Plasmodium sp., has a complex life cycle and is armed with various mechanisms which ensure its continuous transmission. Gametocytes represent the sexual stage of the parasite and are indispensable for the transmission of the parasite from the human host to the mosquito. Despite its vital role in the parasite's success, it is the least understood stage in the parasite's life cycle. The presence of gametocytes in asymptomatic populations and induction of gametocytogenesis by most antimalarial drugs warrants further investigation into its biology. With a renewed focus on malaria elimination and advent of modern technology available to biologists today, the field of gametocyte biology has developed swiftly, providing crucial insights into the molecular mechanisms driving sexual commitment. This review will summarise key current findings in the field of gametocyte biology and address the associated challenges faced in malaria detection, control and elimination.
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19
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Abstract
Eukaryotic pathogens must survive in different hosts, respond to changing environments, and exploit specialized niches to propagate. Plasmodium parasites cause human malaria during bloodstream infections, where they must persist long enough to be transmitted. Parasites have evolved diverse strategies of variant gene expression that control critical biological processes of blood-stage infections, including antigenic variation, erythrocyte invasion, innate immune evasion, and nutrient acquisition, as well as life-cycle transitions. Epigenetic mechanisms within the parasite are being elucidated, with discovery of epigenomic marks associated with gene silencing and activation, and the identification of epigenetic regulators and chromatin proteins that are required for the switching and maintenance of gene expression. Here, we review the key epigenetic processes that facilitate transition through the parasite life cycle and epigenetic regulatory mechanisms utilized by Plasmodium parasites to survive changing environments and consider epigenetic switching in the context of the outcome of human infections.
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Affiliation(s)
- Manoj T Duraisingh
- Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, Massachusetts 02115, USA; ,
| | - Kristen M Skillman
- Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, Massachusetts 02115, USA; ,
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