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J P Dubey - One of the best experts on this subject based on the ideXlab platform.
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endogenous developmental cycle of the human coccidian cyclospora cayetanensis
Journal of Parasitology, 2020Co-Authors: J P Dubey, S Almeria, Joseph Mowery, J FortesAbstract:Cyclospora cayetanensis is a coccidian parasite of humans of known and growing importance. However, we are surprisingly naive as to our understanding of how to diagnose it and how it develops inside the human Body. Here we provide details of the developmental stages of C. cayetanensis in the gallbladder of a 33-yr-old male with human immunodeficiency virus. The gallbladder was removed surgically in 2001 because of severe abdominal pain. For the present study, the archived paraffin block of gallbladder was processed for light microscopy and transmission electron microscopy (TEM). Histological sections were examined after staining with hematoxylin and eosin (HE) or using the periodic acid Schiff (PAS) reaction. Immature and mature asexual stages, gamonts, and oocysts were seen in epithelial cells, both in the superficial epithelium and in glands. The merozoites were present singly, in pairs, and 3 or more in a single parasitophorous vacuole in the host cytoplasm. Up to 6 nuclei were seen in immature schizonts without evidence of merozoite formation. Mature schizonts were 7.6 × 5.1 µm and contained up to 10, 3–4 µm long merozoites. Merozoites were 0.6 to 2.0 µm wide, and their shape varied from pear-shaped to slender. Merozoites were generally PAS-positive; however, some were intensely positive, some had only minute granules, while others were PAS-negative. The microgamonts (male) were 6.6 × 5.2 µm and contained fewer than 20 microgametes around a Residual Body. The microgametes were up to 2 µm long and were flagellated. Macrogamonts (female) contained distinctive eosinophilic wall-forming bodies that varied in size and were less than 1 µm in HE-stained sections. Macrogamonts were 5.8–6.5 × 5.3–6.5 µm. Oocysts in sections were unsporulated and had a diameter of 5.7–7.5 µm. The TEM examination confirmed the histologic findings. The DNA extracted from paraffin sections was confirmed as C. cayetanensis with real-time PCR. The detailed description of the life cycle stages of C. cayetanensis reported here in an immunosuppressed patient could facilitate histopathologic diagnosis of this parasite. We have shown that the parasite's development more closely resembles that of Cystoisospora than Eimeria and that the parasite has multiple nuclei per immature meront indicating schizogony, and we have undermined evidence for a Type II meront.
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hepatic sarcocystosis in a striped dolphin stenella coeruleoalba from the spanish mediterranean coast
Journal of Parasitology, 2002Co-Authors: A R Resendes, Carles Juansalles, S Almeria, M Domingo, Natàlia Majó, J P DubeyAbstract:Fatal hepatic sarcocystosis was diagnosed in a striped dolphin (Stenella coeruleoalba) from the northeastern Spanish Mediterranean coast based on pathologic findings and the microscopic and ultrastructural characteristics of the intralesional parasite. Main gross lesions were icterus, subcutaneous hemorrhages, and hepatic congestion. The most prominent microscopic lesions consisted of severe acute multifocal to coalescing necrotizing hepatitis with cholestasis and intralesional protozoa. There was severe chronic pancreatitis with generalized distension of pancreatic ducts by hyaline plugs and adult trematodes. Only asexual stages of the protozoa were found. The parasite in the liver divided by endopolygeny. Schizonts varied in shape and size. Mature schizonts had merozoites randomly arranged or budding peripherally around a central Residual Body. Schizonts were up to 22 μm long, and merozoites were up to 6 μm long. Ultrastructurally, merozoites lacked rhoptries. This parasite failed to react by immunohist...
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sarcocystis lindsayi n sp protozoa sarcocystidae from the south american opossum didelphis albiventris from brazil
Journal of Eukaryotic Microbiology, 2001Co-Authors: J P Dubey, Benjamin M Rosenthal, C. A. SpeerAbstract:Abstract A new species, Sarcocystis lindsayi n. sp., is proposed for a parasite resembling Sarcocystis falcatula. It was obtained from the lungs and muscles of budgerigars (Melopsittacus undulatus) fed sporocysts from a naturally-infected South American opossum, Didelphis albiventris, from Jaboticabal, Brazil. Sarcocysts of S. lindsayi n. sp. in budgerigars are microscopic, up to 600 μm long and up to 50 μm wide. The cyst wall is up to 2 μm thick. Ultrastructurally, the sarcocyst wall consists of numerous slender villar protrusions (up to 2.0 μm long and up to 0.3 μm wide), each with a stylet at its tip. Schizonts in cell culture divide by endopolygeny leaving a Residual Body. Sporocysts are ∼ 12 × 7 μm. The parasite is genetically distinct from other organisms that also cycle between opossums and avian species and resemble S. falcatula. Diagnostic genetic variation has been observed in the nuclear large subunit ribosomal RNA gene, the internal transcribed spacer (ITS-1), and each of two other genetic loc...
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characterization of an unidentified sarcocystis falcatula like parasite from the south american opossum didelphis albiventris from brazil
Journal of Eukaryotic Microbiology, 2000Co-Authors: J P Dubey, David S Lindsay, P C B Rezende, A J CostaAbstract:An unidentified isolate of a Sarcocystis falcatula-like parasite was obtained from the lungs of budgerigars (Melopsittacus undulatus) fed sporocysts from a naturally-infected South American opossum, Didelphis albiventris from Brazil. Four captive budgerigars fed sporocysts from the opossum intestine died of acute sarcocystosis 8, 10, and 12 days after oral inoculation (DAI); one budgerigar was killed 12 DAI when it was lethargic. Schizonts and merozoites found in the lungs of the budgerigars reacted mildly with polyclonal S. falcatula antiBody. The parasite was isolated in equine kidney cell cultures inoculated with lung tissue from a budgerigar that was killed 12 DAI. Two budgerigars inoculated subcutaneously with 100,000 culture-derived S. falcatula merozoites developed acute sarcocystosis and S. falcatula-like schizonts were found in their lungs 15 and 16 DAI. Four budgerigars kept as unfed controls in the same environment remained free of Sarcocystis infection. The parasite underwent schizogony in African green monkey kidney cells and bovine turbinate cells. Merozoites divided by endopolygeny, often leaving a Residual Body. Polymerase chain reaction studies using primers JNB33/JNB54 and Hinf I and Dra I digestion indicated that the isolate was not S. falcatula. Results of this study indicated that the South American opossum, D. albiventris, is a definitive host for yet another S. falcatula-like parasite.
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development of sarcocystis falcatula in cell cultures demonstrates that it is different from sarcocystis neurona
Parasitology, 1999Co-Authors: David S Lindsay, J P Dubey, K M Horton, Dwight D BowmanAbstract:The development of Sarcocystis falcatula merozoites in bovine turbinate (BT) cell cultures is described and compared with development of Sarcocystis neurona merozoites. Merozoites of S. falcatula entered BT cell cultures and increased in size until 3 days post-inoculation when the nucleus of some merozoites developed lobes. Developing schizonts present at 4 days contained a lobed nucleus or appeared multinucleate. A single mature schizont was observed 4 days p.i. Schizonts were numerous 5 and 6 days p.i. Merozoites were produced from blastophores on the schizont. S. neurona merozoites developed to mature schizonts by 3 days p.i. in BT cells and a Residual Body was often present. Transmission electron microscopy revealed that S. falcatula merozoites possessed more micronemes than did S. neurona merozoites. Our study demonstrates that S. falcatula and S. neurona are not the same parasite.
Jordan D Ward - One of the best experts on this subject based on the ideXlab platform.
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the conserved molting circadian rhythm regulator nhr 23 nr1f1 serves as an essential co regulator of c elegans spermatogenesis
Development, 2020Co-Authors: James Matthew Ragle, Abigail L Aita, Kayleigh N Morrison, Raquel Martinezmendez, Hannah N Saeger, Guinevere Ashley, Londen C Johnson, Katherine Schubert, Diane C Shakes, Jordan D WardAbstract:In sexually reproducing metazoans, spermatogenesis is the process by which uncommitted germ cells give rise to haploid sperm. Work in model systems has revealed mechanisms controlling commitment to the sperm fate, but how this fate is subsequently executed remains less clear. While studying the well-established role of the conserved nuclear hormone receptor transcription factor, NHR-23/NR1F1, in regulating C. elegans molting, we discovered that NHR-23/NR1F1 is also constitutively expressed in developing primary spermatocytes and is a critical regulator of spermatogenesis. In this novel role, NHR-23/NR1F1 functions downstream of the canonical sex-determination pathway. Degron-mediated depletion of NHR-23/NR1F1 within hermaphrodite or male germlines causes sterility due to an absence of functional sperm, as depleted animals produce arrested primary spermatocytes rather than haploid sperm. These spermatocytes arrest in prometaphase I and fail to either progress to anaphase or attempt spermatid-Residual Body partitioning. They make sperm-specific membranous organelles but fail to assemble their major sperm protein into fibrous bodies. NHR-23/NR1F1 appears to function independently of the known SPE-44 gene regulatory network, revealing the existence of an NHR-23/NR1F1-mediated module that regulates the spermatogenesis program.
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the conserved molting circadian rhythm regulator nhr 23 nr1f1 serves as an essential co regulator of c elegans spermatogenesis
bioRxiv, 2020Co-Authors: James Matthew Ragle, Abigail L Aita, Kayleigh N Morrison, Raquel Martinezmendez, Hannah N Saeger, Guinevere Ashley, Londen C Johnson, Katherine Schubert, Diane C Shakes, Jordan D WardAbstract:Abstract In sexually reproducing metazoans, spermatogenesis is the process by which uncommitted germ cells give rise to haploid sperm. Work in model systems has revealed mechanisms controlling commitment to the sperm fate, but how this fate is subsequently executed remains less clear. While studying the well-established role of the conserved nuclear hormone receptor transcription factor, NHR-23/NR1F1, in regulation of C. elegans molting, we discovered NHR-23/NR1F1 is also constitutively expressed in developing 1° spermatocytes and is a critical regulator of spermatogenesis. In this novel role, NHR-23/NR1F1 functions downstream of the canonical sex determination pathway. Degron-mediated depletion of NHR-23/NR1F1 within hermaphrodite or male germlines causes sterility due to an absence of functional sperm as depleted animals produce arrested primary spermatocytes rather than haploid sperm. These spermatocytes arrest in prometaphase I and fail to either progress to anaphase or attempt spermatid-Residual Body partitioning. They make sperm-specific membranous organelles (MOs) but fail to assemble their major sperm protein into fibrous bodies. NHR-23/NR1F1 appears to function independently of the known SPE-44 gene regulatory network, revealing the existence of an NHR-23/NR1F1-mediated module that regulates the spermatogenesis program. Summary Statement A well-characterized regulator of C. elegans molting also unexpectedly controls the spermatogenesis program; our work provides insights into the gene regulatory networks controlling spermatogenesis.
James Matthew Ragle - One of the best experts on this subject based on the ideXlab platform.
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the conserved molting circadian rhythm regulator nhr 23 nr1f1 serves as an essential co regulator of c elegans spermatogenesis
Development, 2020Co-Authors: James Matthew Ragle, Abigail L Aita, Kayleigh N Morrison, Raquel Martinezmendez, Hannah N Saeger, Guinevere Ashley, Londen C Johnson, Katherine Schubert, Diane C Shakes, Jordan D WardAbstract:In sexually reproducing metazoans, spermatogenesis is the process by which uncommitted germ cells give rise to haploid sperm. Work in model systems has revealed mechanisms controlling commitment to the sperm fate, but how this fate is subsequently executed remains less clear. While studying the well-established role of the conserved nuclear hormone receptor transcription factor, NHR-23/NR1F1, in regulating C. elegans molting, we discovered that NHR-23/NR1F1 is also constitutively expressed in developing primary spermatocytes and is a critical regulator of spermatogenesis. In this novel role, NHR-23/NR1F1 functions downstream of the canonical sex-determination pathway. Degron-mediated depletion of NHR-23/NR1F1 within hermaphrodite or male germlines causes sterility due to an absence of functional sperm, as depleted animals produce arrested primary spermatocytes rather than haploid sperm. These spermatocytes arrest in prometaphase I and fail to either progress to anaphase or attempt spermatid-Residual Body partitioning. They make sperm-specific membranous organelles but fail to assemble their major sperm protein into fibrous bodies. NHR-23/NR1F1 appears to function independently of the known SPE-44 gene regulatory network, revealing the existence of an NHR-23/NR1F1-mediated module that regulates the spermatogenesis program.
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the conserved molting circadian rhythm regulator nhr 23 nr1f1 serves as an essential co regulator of c elegans spermatogenesis
bioRxiv, 2020Co-Authors: James Matthew Ragle, Abigail L Aita, Kayleigh N Morrison, Raquel Martinezmendez, Hannah N Saeger, Guinevere Ashley, Londen C Johnson, Katherine Schubert, Diane C Shakes, Jordan D WardAbstract:Abstract In sexually reproducing metazoans, spermatogenesis is the process by which uncommitted germ cells give rise to haploid sperm. Work in model systems has revealed mechanisms controlling commitment to the sperm fate, but how this fate is subsequently executed remains less clear. While studying the well-established role of the conserved nuclear hormone receptor transcription factor, NHR-23/NR1F1, in regulation of C. elegans molting, we discovered NHR-23/NR1F1 is also constitutively expressed in developing 1° spermatocytes and is a critical regulator of spermatogenesis. In this novel role, NHR-23/NR1F1 functions downstream of the canonical sex determination pathway. Degron-mediated depletion of NHR-23/NR1F1 within hermaphrodite or male germlines causes sterility due to an absence of functional sperm as depleted animals produce arrested primary spermatocytes rather than haploid sperm. These spermatocytes arrest in prometaphase I and fail to either progress to anaphase or attempt spermatid-Residual Body partitioning. They make sperm-specific membranous organelles (MOs) but fail to assemble their major sperm protein into fibrous bodies. NHR-23/NR1F1 appears to function independently of the known SPE-44 gene regulatory network, revealing the existence of an NHR-23/NR1F1-mediated module that regulates the spermatogenesis program. Summary Statement A well-characterized regulator of C. elegans molting also unexpectedly controls the spermatogenesis program; our work provides insights into the gene regulatory networks controlling spermatogenesis.
John E Hyde - One of the best experts on this subject based on the ideXlab platform.
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dynamic subcellular localization of isoforms of the folate pathway enzyme serine hydroxymethyltransferase shmt through the erythrocytic cycle of plasmodium falciparum
Malaria Journal, 2010Co-Authors: Martin Read, Ingrid B Muller, Sarah L Mitchell, Paul F G Sims, John E HydeAbstract:The folate pathway enzyme serine hydroxymethyltransferase (SHMT) converts serine to glycine and 5,10-methylenetetrahydrofolate and is essential for the acquisition of one-carbon units for subsequent transfer reactions. 5,10-methylenetetrahydrofolate is used by thymidylate synthase to convert dUMP to dTMP for DNA synthesis. In Plasmodium falciparum an enzymatically functional SHMT (PfSHMTc) and a related, apparently inactive isoform (PfSHMTm) are found, encoded by different genes. Here, patterns of localization of the two isoforms during the parasite erythrocytic cycle are investigated. Polyclonal antibodies were raised to PfSHMTc and PfSHMTm, and, together with specific markers for the mitochondrion and apicoplast, were employed in quantitative confocal fluorescence microscopy of blood-stage parasites. As well as the expected cytoplasmic occupancy of PfSHMTc during all stages, localization into the mitochondrion and apicoplast occurred in a stage-specific manner. Although early trophozoites lacked visible organellar PfSHMTc, a significant percentage of parasites showed such fluorescence during the mid-to-late trophozoite and schizont stages. In the case of the mitochondrion, the majority of parasites in these stages at any given time showed no marked PfSHMTc fluorescence, suggesting that its occupancy of this organelle is of limited duration. PfSHMTm showed a distinctly more pronounced mitochondrial location through most of the erythrocytic cycle and GFP-tagging of its N-terminal region confirmed the predicted presence of a mitochondrial signal sequence. Within the apicoplast, a majority of mitotic schizonts showed a marked concentration of PfSHMTc, whose localization in this organelle was less restricted than for the mitochondrion and persisted from the late trophozoite to the post-mitotic stages. PfSHMTm showed a broadly similar distribution across the cycle, but with a distinctive punctate accumulation towards the ends of elongating apicoplasts. In very late post-mitotic schizonts, both PfSHMTc and PfSHMTm were concentrated in the central region of the parasite that becomes the Residual Body on erythrocyte lysis and merozoite release. Both PfSHMTc and PfSHMTm show dynamic, stage-dependent localization among the different compartments of the parasite and sequence analysis suggests they may also reversibly associate with each other, a factor that may be critical to folate cofactor function, given the apparent lack of enzymic activity of PfSHMTm.
Sarah L Mitchell - One of the best experts on this subject based on the ideXlab platform.
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dynamic subcellular localization of isoforms of the folate pathway enzyme serine hydroxymethyltransferase shmt through the erythrocytic cycle of plasmodium falciparum
Malaria Journal, 2010Co-Authors: Martin Read, Ingrid B Muller, Sarah L Mitchell, Paul F G Sims, John E HydeAbstract:The folate pathway enzyme serine hydroxymethyltransferase (SHMT) converts serine to glycine and 5,10-methylenetetrahydrofolate and is essential for the acquisition of one-carbon units for subsequent transfer reactions. 5,10-methylenetetrahydrofolate is used by thymidylate synthase to convert dUMP to dTMP for DNA synthesis. In Plasmodium falciparum an enzymatically functional SHMT (PfSHMTc) and a related, apparently inactive isoform (PfSHMTm) are found, encoded by different genes. Here, patterns of localization of the two isoforms during the parasite erythrocytic cycle are investigated. Polyclonal antibodies were raised to PfSHMTc and PfSHMTm, and, together with specific markers for the mitochondrion and apicoplast, were employed in quantitative confocal fluorescence microscopy of blood-stage parasites. As well as the expected cytoplasmic occupancy of PfSHMTc during all stages, localization into the mitochondrion and apicoplast occurred in a stage-specific manner. Although early trophozoites lacked visible organellar PfSHMTc, a significant percentage of parasites showed such fluorescence during the mid-to-late trophozoite and schizont stages. In the case of the mitochondrion, the majority of parasites in these stages at any given time showed no marked PfSHMTc fluorescence, suggesting that its occupancy of this organelle is of limited duration. PfSHMTm showed a distinctly more pronounced mitochondrial location through most of the erythrocytic cycle and GFP-tagging of its N-terminal region confirmed the predicted presence of a mitochondrial signal sequence. Within the apicoplast, a majority of mitotic schizonts showed a marked concentration of PfSHMTc, whose localization in this organelle was less restricted than for the mitochondrion and persisted from the late trophozoite to the post-mitotic stages. PfSHMTm showed a broadly similar distribution across the cycle, but with a distinctive punctate accumulation towards the ends of elongating apicoplasts. In very late post-mitotic schizonts, both PfSHMTc and PfSHMTm were concentrated in the central region of the parasite that becomes the Residual Body on erythrocyte lysis and merozoite release. Both PfSHMTc and PfSHMTm show dynamic, stage-dependent localization among the different compartments of the parasite and sequence analysis suggests they may also reversibly associate with each other, a factor that may be critical to folate cofactor function, given the apparent lack of enzymic activity of PfSHMTm.