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Plasmodium falciparum gametocyte development 1 (Pfgdv1) and gametocytogenesis early gene identification and commitment to sexual development.

Eksi S, Morahan BJ, Haile Y, Furuya T, Jiang H, Ali O, Xu H, Kiattibutr K, Suri A, Czesny B, Adeyemo A, Myers TG, Sattabongkot J, Su XZ, Williamson KC - PLoS Pathog. (2012)

Bottom Line: Malaria transmission requires the production of male and female gametocytes in the human host followed by fertilization and sporogonic development in the mosquito midgut.Using a gametocyte-defective parasite line and genetic complementation, we show that Plasmodium falciparumgametocyte development 1 gene (Pfgdv1), encoding a peri-nuclear protein, is critical for early sexual differentiation.The expression profile of one of the early gametocyte specific genes, Pfge1, correlated significantly with asexual parasitemia, which is consistent with the ongoing induction of gametocytogenesis during asexual growth observed in vitro and reinforces the need for sustained transmission-blocking strategies to eliminate malaria.

View Article: PubMed Central - PubMed

Affiliation: Department of Biology, Loyola University Chicago, Chicago, Illinois, USA.

ABSTRACT
Malaria transmission requires the production of male and female gametocytes in the human host followed by fertilization and sporogonic development in the mosquito midgut. Although essential for the spread of malaria through the population, little is known about the initiation of gametocytogenesis in vitro or in vivo. Using a gametocyte-defective parasite line and genetic complementation, we show that Plasmodium falciparumgametocyte development 1 gene (Pfgdv1), encoding a peri-nuclear protein, is critical for early sexual differentiation. Transcriptional analysis of Pfgdv1 negative and positive parasite lines identified a set of gametocytogenesis early genes (Pfge) that were significantly down-regulated (>10 fold) in the absence of Pfgdv1 and expression was restored after Pfgdv1 complementation. Progressive accumulation of Pfge transcripts during successive rounds of asexual replication in synchronized cultures suggests that gametocytes are induced continuously during asexual growth. Comparison of Pfge gene transcriptional profiles in patient samples divided the genes into two groups differing in their expression in mature circulating gametocytes and providing candidates to evaluate gametocyte induction and maturation separately in vivo. The expression profile of one of the early gametocyte specific genes, Pfge1, correlated significantly with asexual parasitemia, which is consistent with the ongoing induction of gametocytogenesis during asexual growth observed in vitro and reinforces the need for sustained transmission-blocking strategies to eliminate malaria.

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Expression analysis of the 3D7.G+ and 3D7.Gdef clones identifies P. falciparumgametocytogenesis early genes (Pfge).Mean ratios of microarray signals (mean±SEM) obtained from the 3D7.G+ and 3D7.Gdef clones at 1.4/0.9% parasitemia (dark gray bar) and at 5.2/5.5% parasitemia (light gray bar), respectively, for the 11 Pfge genes with a ratio of 3D7.G+/3D7.Gdef>10 are plotted in descending order. Pfgdv1 (PFI1710w) had the fourth highest ratio and is indicated by an o. Previously described Pfge genes [17], [20]–[22], [82], are denoted with an asterisk (*) and a vertical line indicates a gene represented by two oligonucleotides. Pfge number, PlasmoDB ID, and common name are listed on the right. The central panel is a summary of the characteristics of the Pfgdv1-dependent genes. The first row (L) indicates whether the gene is subtelomeric (<150 kb from the telomere) (gray square) or within a region of the chromosome that has synteny with other species (black square) [83]. The panel on the left indicates whether the gene encodes a secretory signal sequence (S, black square), PEXEL/HTS export domain (E, black square) or transmembrane domain (T, black square).
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ppat-1002964-g001: Expression analysis of the 3D7.G+ and 3D7.Gdef clones identifies P. falciparumgametocytogenesis early genes (Pfge).Mean ratios of microarray signals (mean±SEM) obtained from the 3D7.G+ and 3D7.Gdef clones at 1.4/0.9% parasitemia (dark gray bar) and at 5.2/5.5% parasitemia (light gray bar), respectively, for the 11 Pfge genes with a ratio of 3D7.G+/3D7.Gdef>10 are plotted in descending order. Pfgdv1 (PFI1710w) had the fourth highest ratio and is indicated by an o. Previously described Pfge genes [17], [20]–[22], [82], are denoted with an asterisk (*) and a vertical line indicates a gene represented by two oligonucleotides. Pfge number, PlasmoDB ID, and common name are listed on the right. The central panel is a summary of the characteristics of the Pfgdv1-dependent genes. The first row (L) indicates whether the gene is subtelomeric (<150 kb from the telomere) (gray square) or within a region of the chromosome that has synteny with other species (black square) [83]. The panel on the left indicates whether the gene encodes a secretory signal sequence (S, black square), PEXEL/HTS export domain (E, black square) or transmembrane domain (T, black square).

Mentions: To identify genes that play an important role in the initial induction of gametocytogenesis, we compared the transcriptional profile of a set of clonal gametocyte-over producing (3D7.G+, average peak gametocytemia ± SEM, 6.97±2.72%) and gametocyte-deficient (3D7.Gdef, average peak gametocytemia ± SEM, 0.009±0.009%) parasite lines. Both lines, 3D7.G+ and 3D7.Gdef, were cloned from P. falciparum strain 3D7 following targeted disruption of Pfs230 (PFB0405w) [14], [15]. RNA was isolated from tightly synchronized cultures on day 4 of gametocyte induction (at parasitemias of 1.4% for 3D7.G+ and 0.9% for 3D7.Gdef) and then again 2 days later at parasitemias of 5.2% and 5.5%, respectively, and was hybridized to a 70-mer oligonucleotide array representing 5,092 P. falciparum genes [16]. Both time points were early in gametocytogenesis, prior to detection of stage II gametocytes in Giemsa-stained culture smears, which in previous studies was the first gametocyte-specific time point for the identification of gametocyte-specific transcripts [17]. Using a 10 fold signal difference as a threshold, 11 genes were differentially regulated at both time points (Fig. 1) and an additional 9 genes had a≥5 fold signal difference (p<0.05) (Table S1). They include seven known gametocyte specific genes Pfg27, Pfs16, Pfg14.744, Pfg14.748, Pfs47, Pfmdv1, and Pfgeco[18]–[23]. These seven genes, as well as PF11_0038, PF14_0290, PF14_0588, PF14_0708 and PF14_0735 have also been identified by proteomic analysis of stage I/II gametocytes; while the remaining genes have not been associated with gametocytogenesis [24]. The differential expression patterns of the 11 genes were confirmed using reverse transcriptase-quantitative polymerase chain reaction (RT-qPCR) or northern blots and were designated as P. falciparumgametocytogenesis early (Pfge) 1 to 11 according to their 3D7.G+/3D7.Gdef signal ratio at the first time point (Fig. 1 and Table S1). This name will be used for those genes without a common name; for example, PF14_0744 had the highest signal ratio and was named Pfge1. Pfge genes 1–8 are located in subtelomeric regions (<150 kB from the telomere) and, except for Pfge4, only have close orthologs (Blast E score≤10−35) in P. reichenowi. Nine of the Pfge genes were predicted to have signals for secretion and/or export to the erythrocyte, which was consistent with gametocyte-specific modifications of the external environment being an early step in sexual differentiation.


Plasmodium falciparum gametocyte development 1 (Pfgdv1) and gametocytogenesis early gene identification and commitment to sexual development.

Eksi S, Morahan BJ, Haile Y, Furuya T, Jiang H, Ali O, Xu H, Kiattibutr K, Suri A, Czesny B, Adeyemo A, Myers TG, Sattabongkot J, Su XZ, Williamson KC - PLoS Pathog. (2012)

Expression analysis of the 3D7.G+ and 3D7.Gdef clones identifies P. falciparumgametocytogenesis early genes (Pfge).Mean ratios of microarray signals (mean±SEM) obtained from the 3D7.G+ and 3D7.Gdef clones at 1.4/0.9% parasitemia (dark gray bar) and at 5.2/5.5% parasitemia (light gray bar), respectively, for the 11 Pfge genes with a ratio of 3D7.G+/3D7.Gdef>10 are plotted in descending order. Pfgdv1 (PFI1710w) had the fourth highest ratio and is indicated by an o. Previously described Pfge genes [17], [20]–[22], [82], are denoted with an asterisk (*) and a vertical line indicates a gene represented by two oligonucleotides. Pfge number, PlasmoDB ID, and common name are listed on the right. The central panel is a summary of the characteristics of the Pfgdv1-dependent genes. The first row (L) indicates whether the gene is subtelomeric (<150 kb from the telomere) (gray square) or within a region of the chromosome that has synteny with other species (black square) [83]. The panel on the left indicates whether the gene encodes a secretory signal sequence (S, black square), PEXEL/HTS export domain (E, black square) or transmembrane domain (T, black square).
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3475683&req=5

ppat-1002964-g001: Expression analysis of the 3D7.G+ and 3D7.Gdef clones identifies P. falciparumgametocytogenesis early genes (Pfge).Mean ratios of microarray signals (mean±SEM) obtained from the 3D7.G+ and 3D7.Gdef clones at 1.4/0.9% parasitemia (dark gray bar) and at 5.2/5.5% parasitemia (light gray bar), respectively, for the 11 Pfge genes with a ratio of 3D7.G+/3D7.Gdef>10 are plotted in descending order. Pfgdv1 (PFI1710w) had the fourth highest ratio and is indicated by an o. Previously described Pfge genes [17], [20]–[22], [82], are denoted with an asterisk (*) and a vertical line indicates a gene represented by two oligonucleotides. Pfge number, PlasmoDB ID, and common name are listed on the right. The central panel is a summary of the characteristics of the Pfgdv1-dependent genes. The first row (L) indicates whether the gene is subtelomeric (<150 kb from the telomere) (gray square) or within a region of the chromosome that has synteny with other species (black square) [83]. The panel on the left indicates whether the gene encodes a secretory signal sequence (S, black square), PEXEL/HTS export domain (E, black square) or transmembrane domain (T, black square).
Mentions: To identify genes that play an important role in the initial induction of gametocytogenesis, we compared the transcriptional profile of a set of clonal gametocyte-over producing (3D7.G+, average peak gametocytemia ± SEM, 6.97±2.72%) and gametocyte-deficient (3D7.Gdef, average peak gametocytemia ± SEM, 0.009±0.009%) parasite lines. Both lines, 3D7.G+ and 3D7.Gdef, were cloned from P. falciparum strain 3D7 following targeted disruption of Pfs230 (PFB0405w) [14], [15]. RNA was isolated from tightly synchronized cultures on day 4 of gametocyte induction (at parasitemias of 1.4% for 3D7.G+ and 0.9% for 3D7.Gdef) and then again 2 days later at parasitemias of 5.2% and 5.5%, respectively, and was hybridized to a 70-mer oligonucleotide array representing 5,092 P. falciparum genes [16]. Both time points were early in gametocytogenesis, prior to detection of stage II gametocytes in Giemsa-stained culture smears, which in previous studies was the first gametocyte-specific time point for the identification of gametocyte-specific transcripts [17]. Using a 10 fold signal difference as a threshold, 11 genes were differentially regulated at both time points (Fig. 1) and an additional 9 genes had a≥5 fold signal difference (p<0.05) (Table S1). They include seven known gametocyte specific genes Pfg27, Pfs16, Pfg14.744, Pfg14.748, Pfs47, Pfmdv1, and Pfgeco[18]–[23]. These seven genes, as well as PF11_0038, PF14_0290, PF14_0588, PF14_0708 and PF14_0735 have also been identified by proteomic analysis of stage I/II gametocytes; while the remaining genes have not been associated with gametocytogenesis [24]. The differential expression patterns of the 11 genes were confirmed using reverse transcriptase-quantitative polymerase chain reaction (RT-qPCR) or northern blots and were designated as P. falciparumgametocytogenesis early (Pfge) 1 to 11 according to their 3D7.G+/3D7.Gdef signal ratio at the first time point (Fig. 1 and Table S1). This name will be used for those genes without a common name; for example, PF14_0744 had the highest signal ratio and was named Pfge1. Pfge genes 1–8 are located in subtelomeric regions (<150 kB from the telomere) and, except for Pfge4, only have close orthologs (Blast E score≤10−35) in P. reichenowi. Nine of the Pfge genes were predicted to have signals for secretion and/or export to the erythrocyte, which was consistent with gametocyte-specific modifications of the external environment being an early step in sexual differentiation.

Bottom Line: Malaria transmission requires the production of male and female gametocytes in the human host followed by fertilization and sporogonic development in the mosquito midgut.Using a gametocyte-defective parasite line and genetic complementation, we show that Plasmodium falciparumgametocyte development 1 gene (Pfgdv1), encoding a peri-nuclear protein, is critical for early sexual differentiation.The expression profile of one of the early gametocyte specific genes, Pfge1, correlated significantly with asexual parasitemia, which is consistent with the ongoing induction of gametocytogenesis during asexual growth observed in vitro and reinforces the need for sustained transmission-blocking strategies to eliminate malaria.

View Article: PubMed Central - PubMed

Affiliation: Department of Biology, Loyola University Chicago, Chicago, Illinois, USA.

ABSTRACT
Malaria transmission requires the production of male and female gametocytes in the human host followed by fertilization and sporogonic development in the mosquito midgut. Although essential for the spread of malaria through the population, little is known about the initiation of gametocytogenesis in vitro or in vivo. Using a gametocyte-defective parasite line and genetic complementation, we show that Plasmodium falciparumgametocyte development 1 gene (Pfgdv1), encoding a peri-nuclear protein, is critical for early sexual differentiation. Transcriptional analysis of Pfgdv1 negative and positive parasite lines identified a set of gametocytogenesis early genes (Pfge) that were significantly down-regulated (>10 fold) in the absence of Pfgdv1 and expression was restored after Pfgdv1 complementation. Progressive accumulation of Pfge transcripts during successive rounds of asexual replication in synchronized cultures suggests that gametocytes are induced continuously during asexual growth. Comparison of Pfge gene transcriptional profiles in patient samples divided the genes into two groups differing in their expression in mature circulating gametocytes and providing candidates to evaluate gametocyte induction and maturation separately in vivo. The expression profile of one of the early gametocyte specific genes, Pfge1, correlated significantly with asexual parasitemia, which is consistent with the ongoing induction of gametocytogenesis during asexual growth observed in vitro and reinforces the need for sustained transmission-blocking strategies to eliminate malaria.

Show MeSH
Related in: MedlinePlus