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Díez J, Moreno G, Del Peral L, Adams JH, Rodríguez Frías MD, Manjón JL. Fuligo septica Spores Onboard a Stratospheric NASA Balloon and Its Complete In Vitro Life Cycle. Astrobiology 2020; 20:394-404. [PMID: 32027169 DOI: 10.1089/ast.2019.2097] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The aim of this study was to demonstrate for the first time Fuligo septica spore viability in the stratosphere through spore germination and its complete life cycle. These protozoan spores were flown by the National Aeronautics and Space Administration (NASA) Columbia Scientific Balloon Facility (CSBF) flight 667NT, launched from its base in Fort Sumner, New Mexico. F. septica spores were exposed to stratospheric conditions on board the NASA/CSBF 667 balloon flight for 9 h. The spores obtained after the flight and those from the control box that stayed at ground maintained the same size and morphology, as will be shown in this work. The spores retained viability, and all life cycle stages were obtained by in vitro culture. Moreover, some life cycle events were observed for the first time in F. septica.
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Affiliation(s)
- Jaime Díez
- Dpto. de Ciencias de la Vida, Facultad de Ciencias, Universidad de Alcalá, 28805 Alcalá de Henares, Spain
| | - Gabriel Moreno
- Dpto. de Ciencias de la Vida, Facultad de Ciencias, Universidad de Alcalá, 28805 Alcalá de Henares, Spain
| | - Luis Del Peral
- Dpto. de Física y Matemáticas, Space and Astroparticle Group, Facultad de Ciencias, Universidad de Alcalá, 28805 Alcalá de Henares, Spain
| | - James H Adams
- Center for Space Plasma and Aeronomic Research (CSPAR), University of Alabama in Huntsville, Huntsville, Alabama, United States
| | - María D Rodríguez Frías
- Dpto. de Física y Matemáticas, Space and Astroparticle Group, Facultad de Ciencias, Universidad de Alcalá, 28805 Alcalá de Henares, Spain
| | - José L Manjón
- Dpto. de Ciencias de la Vida, Facultad de Ciencias, Universidad de Alcalá, 28805 Alcalá de Henares, Spain
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Harding MW, Hill TB, Yang Y, Daniels GC, Hwang SF, Strelkov SE, Howard RJ, Feng J. An Improved Evans Blue Staining Method for Consistent, Accurate Assessment of Plasmodiophora brassicae Resting Spore Viability. Plant Dis 2019; 103:2330-2336. [PMID: 31298992 DOI: 10.1094/pdis-05-18-0855-re] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Clubroot caused by Plasmodiophora brassicae is an important disease of brassica crops. The use of vital stains to determine the viability of P. brassicae resting spores can provide useful information regarding spore longevity, inoculum potential, or the efficacy of antimicrobial treatments. Evans blue is one example of a vital stain that has been reported to differentially stain viable and nonviable resting spores. Some previously published protocols using Evans blue to stain P. brassicae resting spores have not provided accurate or consistent results. In this study, we modified the Evans blue method by increasing the staining time to 8 h or more and evaluated P. brassicae resting spores after heat treatment at various combinations of temperature and time. Extending staining times significantly increased the numbers of stained resting spores up to 7 h, after which the numbers of stained spores did not change significantly (R2 = 96.88; P ≤ 0.001). The accuracy of the modified method to discriminate viable and nonviable spores was evaluated in repeated experiments and by comparing the staining data with those derived from inoculation assays and propidium monoazide quantitative PCR (qPCR). The results demonstrated that the modified Evans blue staining method improved the accuracy and consistency of measurement of P. brassicae resting spore viability. Additionally, it was equivalent to the qPCR method for differentiating viable and nonviable spores (R2 = 99.84; P ≤ 0.001) and confirmed in canola infection bioassays.
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Affiliation(s)
- M W Harding
- Crop Diversification Centre South, Alberta Agriculture and Forestry, Brooks, AB T1R 1E6, Canada
| | - T B Hill
- Crop Diversification Centre South, Alberta Agriculture and Forestry, Brooks, AB T1R 1E6, Canada
| | - Y Yang
- Crop Diversification Centre North, Alberta Agriculture and Forestry, Edmonton, AB T5Y 6H3, Canada
| | - G C Daniels
- Crop Diversification Centre South, Alberta Agriculture and Forestry, Brooks, AB T1R 1E6, Canada
| | - S F Hwang
- Crop Diversification Centre North, Alberta Agriculture and Forestry, Edmonton, AB T5Y 6H3, Canada
| | - S E Strelkov
- Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, AB T6G 2P5, Canada
| | - R J Howard
- RJH Ag Research Solutions Ltd., Brooks, AB T1R 1C3, Canada
| | - J Feng
- Crop Diversification Centre North, Alberta Agriculture and Forestry, Edmonton, AB T5Y 6H3, Canada
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Kondo AP, Narita TB, Murata C, Ogura T, Mikagi A, Usuki T, Saito T. 4-Methyl-5-Pentylbenzene-1,3-Diol Regulates Chemotactic Cell Aggregation and Spore Maturation Via Different Mechanisms in Dictyostelium discoideum. Curr Microbiol 2019; 76:376-381. [PMID: 30710153 DOI: 10.1007/s00284-019-01639-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2018] [Accepted: 01/21/2019] [Indexed: 11/25/2022]
Abstract
4-Methyl-5-pentylbenzene-1,3-diol (MPBD), a product of the polyketide synthase SteelyA, is a signaling molecule that regulates Dictyostelium discoideum development. During early development, MPBD controls chemotactic cell aggregation by regulating the expression of genes in the cAMP signaling pathway; however, during culmination at late development, it induces spore maturation. In the present study, we analyzed the effects of MPBD, its derivatives, and a putative MPBD-derived metabolite on developmental defects in the MPBD-less stlA null mutant. Using structure-activity relationship studies, it was observed that in MPBD, the functional groups that were essential for induction of spore maturation were different from those essential for induction of cell aggregation. Dictyoquinone, a putative MPBD metabolite rescued the aggregation defect in stlA null mutant in early development, but not the spore maturation defect at the later stage. Our data suggest that MPBD regulates chemotactic cell aggregation and spore maturation via different mechanisms.
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Affiliation(s)
- Anna P Kondo
- Graduate School of Science and Technology, Sophia University, Tokyo, 102-8554, Japan
| | - Takaaki B Narita
- Graduate School of Science and Technology, Sophia University, Tokyo, 102-8554, Japan
- Faculty of Science and Technology, Sophia University, Tokyo, 102-8554, Japan
| | - Chihiro Murata
- Graduate School of Science and Technology, Sophia University, Tokyo, 102-8554, Japan
| | - Tetsuhiro Ogura
- Graduate School of Science and Technology, Sophia University, Tokyo, 102-8554, Japan
| | - Ayame Mikagi
- Graduate School of Science and Technology, Sophia University, Tokyo, 102-8554, Japan
| | - Toyonobu Usuki
- Faculty of Science and Technology, Sophia University, Tokyo, 102-8554, Japan
| | - Tamao Saito
- Faculty of Science and Technology, Sophia University, Tokyo, 102-8554, Japan.
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Tooley PW, Browning M. Sporangia Production Over Time by Phytophthora ramorum on Rhododendron 'Cunningham's White' After Placement at Different Relative Humidities. Phytopathology 2018; 108:721-729. [PMID: 29671704 DOI: 10.1094/phyto-10-17-0338-r] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
We examined the impact of relative humidity (RH) on Phytophthora ramorum sporangia production on Rhododendron 'Cunningham's White'. When diseased plants were maintained under continuous moisture in a mist tent, sporangia were collected from some plants for 22 weeks. More than 3,000 sporangia/leaf/week were collected over the first 3 weeks but levels declined to <100 sporangia/leaf/week after 7 weeks. We also examined the impact of drying on P. ramorum sporangia production. Diseased, detached leaves were maintained in humidity chambers (100, 96.2, 84.5, 74.9, and 56.2% RH) for up to 9 weeks and removed weekly to assess sporulation. For comparison, diseased leaves were harvested from plants maintained with dry foliage or subjected to 10 h of simulated dew nightly. All leaves supported sporulation following 5 weeks at 100% RH, 3 weeks at 96.2% RH, and 1 week at 84.5% RH. All leaves collected from plants subjected to nightly dew supported sporulation for 3 weeks; however, only 66.7% of leaves collected from plants with dry foliage supported sporulation after 1 week. Knowledge of the effects of RH levels on P. ramorum sporulation capacity will prove useful in terms of disease management recommendations and for development of predictive models and pest risk assessments.
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Affiliation(s)
- Paul W Tooley
- United States Department of Agriculture-Agricultural Research Service, Foreign Disease-Weed Science Research Unit, 1301 Ditto Ave., Ft. Detrick, MD 21702
| | - Marsha Browning
- United States Department of Agriculture-Agricultural Research Service, Foreign Disease-Weed Science Research Unit, 1301 Ditto Ave., Ft. Detrick, MD 21702
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Satterfield DA, Altizer S, Williams MK, Hall RJ. Environmental Persistence Influences Infection Dynamics for a Butterfly Pathogen. PLoS One 2017; 12:e0169982. [PMID: 28099501 PMCID: PMC5242512 DOI: 10.1371/journal.pone.0169982] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2016] [Accepted: 12/27/2016] [Indexed: 11/19/2022] Open
Abstract
Many pathogens, including those infecting insects, are transmitted via dormant stages shed into the environment, where they must persist until encountering a susceptible host. Understanding how abiotic conditions influence environmental persistence and how these factors influence pathogen spread are crucial for predicting patterns of infection risk. Here, we explored the consequences of environmental transmission for infection dynamics of a debilitating protozoan parasite (Ophryocystis elektroscirrha) that infects monarch butterflies (Danaus plexippus). We first conducted an experiment to observe the persistence of protozoan spores exposed to natural conditions. Experimental results showed that, contrary to our expectations, pathogen doses maintained high infectivity even after 16 days in the environment, although pathogens did yield infections with lower parasite loads after environmental exposure. Because pathogen longevity exceeded the time span of our experiment, we developed a mechanistic model to better explore environmental persistence for this host-pathogen system. Model analysis showed that, in general, longer spore persistence led to higher infection prevalence and slightly smaller monarch population sizes. The model indicated that typical parasite doses shed onto milkweed plants must remain viable for a minimum of 3 weeks for prevalence to increase during the summer-breeding season, and for 11 weeks or longer to match levels of infection commonly reported from the wild, assuming moderate values for parasite shedding rate. Our findings showed that transmission stages of this butterfly pathogen are long-lived and indicated that this is a necessary condition for the protozoan to persist in local monarch populations. This study provides a modeling framework for future work examining the dynamics of an ecologically important pathogen in an iconic insect.
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Affiliation(s)
- Dara A. Satterfield
- Odum School of Ecology, University of Georgia, Athens, Georgia, United States of America
- * E-mail:
| | - Sonia Altizer
- Odum School of Ecology, University of Georgia, Athens, Georgia, United States of America
| | - Mary-Kate Williams
- Biological Sciences, University of Arkansas at Little Rock, Little Rock, Arkansas, United States of America
| | - Richard J. Hall
- Odum School of Ecology, University of Georgia, Athens, Georgia, United States of America
- Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, Georgia, United States of America
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Balendres MA, Nichols DS, Tegg RS, Wilson CR. Metabolomes of Potato Root Exudates: Compounds That Stimulate Resting Spore Germination of the Soil-Borne Pathogen Spongospora subterranea. J Agric Food Chem 2016; 64:7466-7474. [PMID: 27640528 DOI: 10.1021/acs.jafc.6b03904] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Root exudation has importance in soil chemical ecology influencing rhizosphere microbiota. Prior studies reported root exudates from host and nonhost plants stimulated resting spore germination of Spongospora subterranea, the powdery scab pathogen of potato, but the identities of stimulatory compounds were unknown. This study showed that potato root exudates stimulated S. subterranea resting spore germination, releasing more zoospores at an earlier time than the control. We detected 24 low molecular weight organic compounds within potato root exudates and identified specific amino acids, sugars, organic acids, and other compounds that were stimulatory to S. subterranea resting spore germination. Given that several stimulatory compounds are commonly found in exudates of diverse plant species, we support observations of nonhost-specific stimulation. We provide knowledge of S. subterranea resting spore biology and chemical ecology that may be useful in formulating new disease management strategies.
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Affiliation(s)
- Mark A Balendres
- New Town Research Laboratories, Tasmanian Institute of Agriculture, University of Tasmania , 13 St. Johns Avenue, New Town, Tasmania 7008, Australia
| | - David S Nichols
- Central Science Laboratory, University of Tasmania , Private Bag 74, Hobart, Tasmania 7001, Australia
| | - Robert S Tegg
- New Town Research Laboratories, Tasmanian Institute of Agriculture, University of Tasmania , 13 St. Johns Avenue, New Town, Tasmania 7008, Australia
| | - Calum R Wilson
- New Town Research Laboratories, Tasmanian Institute of Agriculture, University of Tasmania , 13 St. Johns Avenue, New Town, Tasmania 7008, Australia
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Altizer S, Hobson KA, Davis AK, De Roode JC, Wassenaar LI. Do Healthy Monarchs Migrate Farther? Tracking Natal Origins of Parasitized vs. Uninfected Monarch Butterflies Overwintering in Mexico. PLoS One 2015; 10:e0141371. [PMID: 26606389 PMCID: PMC4659535 DOI: 10.1371/journal.pone.0141371] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2015] [Accepted: 10/06/2015] [Indexed: 11/19/2022] Open
Abstract
Long-distance migration can lower parasite prevalence if strenuous journeys remove infected animals from wild populations. We examined wild monarch butterflies (Danaus plexippus) to investigate the potential costs of the protozoan Ophryocystis elektroscirrha on migratory success. We collected monarchs from two wintering sites in central Mexico to compare infection status with hydrogen isotope (δ2H) measurements as an indicator of latitude of origin at the start of fall migration. On average, uninfected monarchs had lower δ2H values than parasitized butterflies, indicating that uninfected butterflies originated from more northerly latitudes and travelled farther distances to reach Mexico. Within the infected class, monarchs with higher quantitative spore loads originated from more southerly latitudes, indicating that heavily infected monarchs originating from farther north are less likely to reach Mexico. We ruled out the alternative explanation that lower latitudes give rise to more infected monarchs prior to the onset of migration using citizen science data to examine regional differences in parasite prevalence during the summer breeding season. We also found a positive association between monarch wing area and estimated distance flown. Collectively, these results emphasize that seasonal migrations can help lower infection levels in wild animal populations. Our findings, combined with recent declines in the numbers of migratory monarchs wintering in Mexico and observations of sedentary (winter breeding) monarch populations in the southern U.S., suggest that shifts from migratory to sedentary behavior will likely lead to greater infection prevalence for North American monarchs.
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Affiliation(s)
- Sonia Altizer
- Odum School of Ecology, University of Georgia, Athens, Georgia, United States of America
- * E-mail:
| | - Keith A. Hobson
- Environment Canada, 11 Innovation Blvd., Saskatoon, Saskatchewan, Canada
- Department of Biology, University of Western Ontario, London, Ontario, Canada
| | - Andrew K. Davis
- Odum School of Ecology, University of Georgia, Athens, Georgia, United States of America
| | - Jacobus C. De Roode
- Department of Biology, Emory University, Atlanta, Georgia, United States of America
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Szczepaniak KO, Tomczuk K, Lojszczyk-Szczepaniak A, Lopuszynski W. Reclassification of Eimeria pogonae Walden (2009) as Choleoeimeria pogonae comb. nov. (Apicomplexa: Eimeriidae). Parasitol Res 2015; 115:681-5. [PMID: 26468146 PMCID: PMC4722055 DOI: 10.1007/s00436-015-4787-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2015] [Accepted: 10/06/2015] [Indexed: 11/27/2022]
Abstract
The presented paper provides a reclassification of Eimeria pogonae from Pogona vitticeps into the correct genus Choleoeimeria. A description of exogenous and endogenous stages of biliary coccidium is given. Sporulation of the oocysts was endogenous. The mature oocysts contained four sporocysts each with two sporozoites. Oocysts were ellipsoidal in shape, with average length/width ratio 1.7 and measured 28.4 (SD1.5) × 16.8 (SD 1.5). The micropyle, residuum, and polar granules were absent from the sporulated oocysts. Ovoidal in shape, sporosysts without Steida bodies contained residuum and two elongated and boat-shaped sporozoites. The endogenous stages of the coccidia were located mainly in the epithelium of bile ducts; however, single-epithelium cells of the gallbladder were also infected.
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Affiliation(s)
| | - Krzysztof Tomczuk
- Faculty of Veterinary Medicine, University of Life Sciences in Lublin, Akademicka 13, Lublin, 20-950 Lubelskie Poland
| | - Anna Lojszczyk-Szczepaniak
- Faculty of Veterinary Medicine, University of Life Sciences in Lublin, Akademicka 13, Lublin, 20-950 Lubelskie Poland
| | - Wojciech Lopuszynski
- Faculty of Veterinary Medicine, University of Life Sciences in Lublin, Akademicka 13, Lublin, 20-950 Lubelskie Poland
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Voronin VN, Dudin AS. [THE DESCRIPTION OF MYXOBOLUS PELECICOLA SP. NOV. (MYXOZOA: MYXOBOLIDAE) FROM PELECUS CULTRATUS (CYPRINIFORMES, CYPRINIDAE)]. Parazitologiia 2015; 49:257-263. [PMID: 26827485] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Morphological study of myxosporean parasites Myxobolus pelecicola sp. n. from Pele- cus cultratus (L., 1758), is presented. Presporogenic stage not observed. Polysporous, el- lipsoidal. plasmodia up to 1.2 mm in length and 0.1 to 0.4 mm in width develop in the ske- letal musculature. Mature spores elongate oval or oval form in frontal view, lens-shaped in sutural view. Length of spores 16.5 ± 0.83 (14.9-18.0), width 12.1 ± 0.63 (11.6-13.3) (n = 50), thickness 7.8 ± 0.3 (7.4-8.3) µm (n = 10). Polar capsules pyriform, unequal, length of large 8.0 ± 0.44 (7.5-8.8), small 7.6 ± 0.26 (7.2-7.8), width of large 4.5 ± 0.22 (4.2-4.7), small 4.0 ± 0.21 (3.8-4.3) µm. Five to 6 distinct filament coils oriented obli- quely to capsule length, found in polar capsule. The length of extruded (in water) filament up to 130 µm. Large, but indistinct triangular intercapsular appendix present in spores. Single rodlet inclusion is very often observed in the posterior part of spore. Mucous enve- lope is absent. The type host of Myxobolus pelecicola sp. n. is sabrefish Pelecus cultratus (L., 1758). Type locality: Finnish Bay (60°05' N 29°55' E) and Ladoga lake (60°07' N 32°19' E), Russia.
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Abstract
BACKGROUND The genus Phytophthora includes a group of agriculturally important pathogens and they are commonly regarded as water molds. They produce motile zoospores that can move via water currents and on their own locomotion in aquatic environments. However, zoosporic response to dissolved oxygen, an important water quality parameter, is not known. Like other water quality parameters, dissolved oxygen concentration in irrigation reservoirs fluctuates dramatically over time. The aim of this study was to determine whether and how zoospore survival may be affected by elevated and low concentrations of dissolved oxygen in water to better understand the aquatic biology of these pathogens in irrigation reservoirs. RESULTS Zoospores of P. megasperma, P. nicotianae, P. pini and P. tropicalis were assessed for survival in 10% Hoagland's solution at a range of dissolved concentrations from 0.9 to 20.1 mg L(-1) for up to seven exposure times from 0 to 72 h. Zoospore survival was measured by resultant colony counts per ml. Zoospores of these species survived the best in control Hoagland's solution at dissolved oxygen concentrations of 5.3 to 5.6 mg L(-1). Zoospore survival rates decreased with increasing and decreasing concentration of dissolved oxygen, depending upon Phytophthora species and exposure time. Overall, P. megasperma and P. pini are less sensitive than P. nicotianae and P. tropicalis to hyperoxia and hypoxia conditions. CONCLUSION Zoospores in the control solution declined over time and this natural decline process was enhanced under hyperoxia and hypoxia conditions. These findings suggest that dramatic fluctuations of dissolved oxygen in irrigation reservoirs contribute to the population decline of Phytophthora species along the water path in the same reservoirs. These findings advanced our understanding of the aquatic ecology of these pathogens in irrigation reservoirs. They also provided a basis for pathogen risk mitigation by prolonging the turnover time of runoff water in recycling irrigation systems via better system designs.
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Affiliation(s)
- Ping Kong
- Virginia Tech, Hampton Roads Agricultural Research and Extension Center, Virginia Beach, VA 23455, USA
| | - Chuanxue Hong
- Virginia Tech, Hampton Roads Agricultural Research and Extension Center, Virginia Beach, VA 23455, USA
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Stallforth P, Brock DA, Cantley AM, Tian X, Queller DC, Strassmann JE, Clardy J. A bacterial symbiont is converted from an inedible producer of beneficial molecules into food by a single mutation in the gacA gene. Proc Natl Acad Sci U S A 2013; 110:14528-33. [PMID: 23898207 PMCID: PMC3767522 DOI: 10.1073/pnas.1308199110] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Stable multipartite mutualistic associations require that all partners benefit. We show that a single mutational step is sufficient to turn a symbiotic bacterium from an inedible but host-beneficial secondary metabolite producer into a host food source. The bacteria's host is a "farmer" clone of the social amoeba Dictyostelium discoideum that carries and disperses bacteria during its spore stage. Associated with the farmer are two strains of Pseudomonas fluorescens, only one of which serves as a food source. The other strain produces diffusible small molecules: pyrrolnitrin, a known antifungal agent, and a chromene that potently enhances the farmer's spore production and depresses a nonfarmer's spore production. Genome sequence and phylogenetic analyses identify a derived point mutation in the food strain that generates a premature stop codon in a global activator (gacA), encoding the response regulator of a two-component regulatory system. Generation of a knockout mutant of this regulatory gene in the nonfood bacterial strain altered its secondary metabolite profile to match that of the food strain, and also, independently, converted it into a food source. These results suggest that a single mutation in an inedible ancestral strain that served a protective role converted it to a "domesticated" food source.
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Affiliation(s)
- Pierre Stallforth
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115; and
| | - Debra A. Brock
- Department of Biology, Washington University in St. Louis, St. Louis, MO 63130
| | - Alexandra M. Cantley
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115; and
| | - Xiangjun Tian
- Department of Biology, Washington University in St. Louis, St. Louis, MO 63130
| | - David C. Queller
- Department of Biology, Washington University in St. Louis, St. Louis, MO 63130
| | - Joan E. Strassmann
- Department of Biology, Washington University in St. Louis, St. Louis, MO 63130
| | - Jon Clardy
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115; and
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Abstract
Dictyostelium discoideum is a commonly used model organism for the study of biological processes such as chemotaxis, cell communication, and development. While these studies primarily focus on a single clone, recent work has revealed a host of questions that can only be answered from studies of multiple genetically distinct clones. Understanding intraspecific clone conflict, kin recognition, differential adhesion, and other kinds of interactions likely to occur in the natural soil habitat can only come from studies of multiple clones. Studies of populations of wild isolates are also important for understanding the factors contributing to associations such as species co-occurrences and to observed inter- and intraspecific interactions such as those found between bacteria and D. discoideum. Natural isolates of Dictyostelium are easily found in soil and leaf litter in nearly all habitats. Here we describe a simple and successful method for isolating new wild clones from soil, then isolating single clonal strains, and storing them for future use.
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Affiliation(s)
- Tracy E Douglas
- Department of Biology, Washington University, St. Louis, MO, USA
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Morris DJ. A new model for myxosporean (Myxozoa) development explains the endogenous budding phenomenon, the nature of cell within cell life stages and evolution of parasitism from a cnidarian ancestor. Int J Parasitol 2012; 42:829-40. [PMID: 22749958 DOI: 10.1016/j.ijpara.2012.06.001] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2012] [Revised: 06/05/2012] [Accepted: 06/06/2012] [Indexed: 11/17/2022]
Abstract
The phylum Myxozoa is composed of endoparasitic species that have predominately been recorded within aquatic vertebrates. The simple body form of a trophic cell containing other cells within it, as observed within these hosts, has provided few clues to relationships with other organisms. In addition, the placement of the group using molecular phylogenies has proved very difficult, although the majority of analyses now suggest that they are cnidarians. There have been relatively few studies of myxozoan stages within invertebrate hosts, even though these exhibit multicellular and sexual stages that may provide clues to myxozoan evolution. Therefore an ultrastructural examination of a myxozoan infection of a freshwater oligochaete was conducted, to reassess and formulate a model for myxozoan development in these hosts. This deemed that meiosis occurs within the oligochaete, but that fertilisation is not immediate. Rather, the resultant haploid germ cell (oocyte) is engulfed by a diploid sporogonic cell (nurse cell) to form a sporoplasm. It is this sporoplasm that infects the fish, resulting in the multicellular stages observed. Fertilisation occurs after the parasites leave the fish and enter the oligochaete host. The nurse cell/oocyte model explains previously conflicting evidence in the literature regarding myxosporean biology, and aligns phenomena considered distinctive to the Myxozoa, such as endogenous budding and cell within cell development, with processes recorded in cnidarians. Finally, the evolutionary origin of the Myxozoa as cnidarian parasites of ova is hypothesised.
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Affiliation(s)
- D J Morris
- Institute of Aquaculture, University of Stirling, Stirling, Scotland, UK.
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Abstract
Free-living cells of the social amoebae Dictyostelium discoideum can aggregate and develop into multicellular fruiting bodies in which many die altruistically as they become stalk cells that support the surviving spores. Dictyostelium cells exhibit kin discrimination--a potential defense against cheaters, which sporulate without contributing to the stalk. Kin discrimination depends on strain relatedness, and the polymorphic genes tgrB1 and tgrC1 are potential components of that mechanism. Here, we demonstrate a direct role for these genes in kin discrimination. We show that a matching pair of tgrB1 and tgrC1 alleles is necessary and sufficient for attractive self-recognition, which is mediated by differential cell-cell adhesion. We propose that TgrB1 and TgrC1 proteins mediate this adhesion through direct binding. This system is a genetically tractable ancient model of eukaryotic self-recognition.
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Affiliation(s)
- Shigenori Hirose
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030, USA
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15
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Myre MA, Lumsden AL, Thompson MN, Wasco W, MacDonald ME, Gusella JF. Deficiency of huntingtin has pleiotropic effects in the social amoeba Dictyostelium discoideum. PLoS Genet 2011; 7:e1002052. [PMID: 21552328 PMCID: PMC3084204 DOI: 10.1371/journal.pgen.1002052] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2010] [Accepted: 03/02/2011] [Indexed: 11/24/2022] Open
Abstract
Huntingtin is a large HEAT repeat protein first identified in humans, where a polyglutamine tract expansion near the amino terminus causes a gain-of-function mechanism that leads to selective neuronal loss in Huntington's disease (HD). Genetic evidence in humans and knock-in mouse models suggests that this gain-of-function involves an increase or deregulation of some aspect of huntingtin's normal function(s), which remains poorly understood. As huntingtin shows evolutionary conservation, a powerful approach to discovering its normal biochemical role(s) is to study the effects caused by its deficiency in a model organism with a short life-cycle that comprises both cellular and multicellular developmental stages. To facilitate studies aimed at detailed knowledge of huntingtin's normal function(s), we generated a null mutant of hd, the HD ortholog in Dictyostelium discoideum. Dictyostelium cells lacking endogenous huntingtin were viable but during development did not exhibit the typical polarized morphology of Dictyostelium cells, streamed poorly to form aggregates by accretion rather than chemotaxis, showed disorganized F-actin staining, exhibited extreme sensitivity to hypoosmotic stress, and failed to form EDTA-resistant cell–cell contacts. Surprisingly, chemotactic streaming could be rescued in the presence of the bivalent cations Ca2+ or Mg2+ but not pulses of cAMP. Although hd− cells completed development, it was delayed and proceeded asynchronously, producing small fruiting bodies with round, defective spores that germinated spontaneously within a glassy sorus. When developed as chimeras with wild-type cells, hd− cells failed to populate the pre-spore region of the slug. In Dictyostelium, huntingtin deficiency is compatible with survival of the organism but renders cells sensitive to low osmolarity, which produces pleiotropic cell autonomous defects that affect cAMP signaling and as a consequence development. Thus, Dictyostelium provides a novel haploid organism model for genetic, cell biological, and biochemical studies to delineate the functions of the HD protein. Genetic evidence in humans and mouse models of Huntington's disease suggests that the disease mutation confers a deleterious gain-of-function on huntingtin that acts through the deregulation of some aspect of the protein's normal function(s). While huntingtin's function is poorly understood, its evolutionary conservation makes investigation of its physiological role in lower organisms an attractive route that has yet to be fully exploited. Therefore, we have used Dictyostelium discoideum to study the consequences of huntingtin (hd) deficiency. Developing Dictyostelium cells chemotax to form a multicellular slug that forms a fruiting body, comprising dormant spores encased above dead stalk cells. We found that hd− cells were hypersensitive to hypoosmotic stress. When starved, hd− cells aggregate by accretion, showed disorganized F-actin, and failed to form EDTA-resistant cell–cell contacts. Surprisingly, chemotactic signaling was rescued with Ca2+ or Mg2+ but not pulses of cAMP. Development of hd− mutants produced small fruiting bodies with round, defective spores, and when mixed with wild-type cells they didn't differentiate into spores. Our results are consistent with mammalian studies that show huntingtin is a multifunctional protein involved in many biochemical processes; and, importantly, they establish Dictyostelium as a valuable experimental organism for exploring in biochemical detail huntingtin's normal function(s).
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Affiliation(s)
- Michael A. Myre
- Molecular Neurogenetics Unit, Center for Human Genetic Research, Massachusetts General Hospital, Boston, Massachusetts, United States of America
- * E-mail:
| | - Amanda L. Lumsden
- Molecular Neurogenetics Unit, Center for Human Genetic Research, Massachusetts General Hospital, Boston, Massachusetts, United States of America
| | - Morgan N. Thompson
- Molecular Neurogenetics Unit, Center for Human Genetic Research, Massachusetts General Hospital, Boston, Massachusetts, United States of America
| | - Wilma Wasco
- Genetics and Aging Research Unit, MassGeneral Institute for Neurodegenerative Disease, Massachusetts General Hospital, Charlestown, Massachusetts, United States of America
| | - Marcy E. MacDonald
- Molecular Neurogenetics Unit, Center for Human Genetic Research, Massachusetts General Hospital, Boston, Massachusetts, United States of America
| | - James F. Gusella
- Molecular Neurogenetics Unit, Center for Human Genetic Research, Massachusetts General Hospital, Boston, Massachusetts, United States of America
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16
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Szczepaniak K, Tomczuk K, Studzińska M. Cutaneus myxosporidiasis in the Australian green tree frog (Litoria caerulea). Parasitol Res 2010; 108:489-92. [PMID: 20922417 PMCID: PMC3024497 DOI: 10.1007/s00436-010-2093-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2010] [Accepted: 09/16/2010] [Indexed: 12/05/2022]
Abstract
This case is reported with the intention of highlighting the presentation of cutaneous myxosporidiasis in Australian tree frog (Litoria caerulea) caused by genus Myxobolus. The morphology and morphometric characteristic of the spores were determined using light microscopy and differential interference contrast microscopy. Spores were pyriform in shape in frontal view and oval in lateral view, and the average size was respectively 11.4 × 6.0 × 4.5 μm (12.1 − 9.5 × 6.3 − 5.4 × 5.0 − 4.1 μm). To the best of our knowledge, this is the second case of skin invasion caused by myxosporeans in amphibians.
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Affiliation(s)
- Klaudiusz Szczepaniak
- Sub-Department of Parasitology and Invasive Diseases, Institute of Biological Bases of Animal Diseases, Faculty of Veterinary Medicine, University of Life Sciences, Akademicka 12, 20-033, Lublin, Poland.
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17
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Oohata AA, Fukuzawa M, Hotta R, Nakagawa M, Niwa M, Takaya Y. Differentiation inducing factors in Dictyostelium discoideum: A novel low molecular factor functions at an early stage(s) of differentiation. Dev Growth Differ 2009; 51:743-52. [PMID: 19824899 DOI: 10.1111/j.1440-169x.2009.01133.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Akiko A Oohata
- Biological Laboratory, Kansai Medical University, 18-89 Uyamahigashimachi, Hirakata, Osaka, Japan.
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18
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Caffara M, Raimondi E, Florio D, Marcer F, Quaglio F, Fioravanti ML. The life cycle of Myxobolus lentisuturalis (Myxozoa: Myxobolidae), from goldfish (Carassius auratus auratus), involves a Raabeia-type actinospore. Folia Parasitol (Praha) 2009; 56:6-12. [PMID: 19391327 DOI: 10.14411/fp.2009.002] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Affiliation(s)
- Monica Caffara
- Department of Veterinary Public Health and Animal Pathology, Alma Mater Studiorum University of Bologna, via Tolara di Sopra 50, 40064 Ozzano Emila, Bologna, Italy.
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19
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West CM, Nguyen P, van der Wel H, Metcalf T, Sweeney KR, Blader IJ, Erdos GW. Dependence of stress resistance on a spore coat heteropolysaccharide in Dictyostelium. Eukaryot Cell 2009; 8:27-36. [PMID: 18996984 PMCID: PMC2620749 DOI: 10.1128/ec.00398-07] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2007] [Accepted: 09/01/2008] [Indexed: 11/20/2022]
Abstract
In Dictyostelium, sporulation occurs synchronously as prespore cells approach the apex of the aerial stalk during culmination. Each prespore cell becomes surrounded by its own coat comprised of a core of crystalline cellulose and a branched heteropolysaccharide sandwiched between heterogeneous cysteine-rich glycoproteins. The function of the heteropolysaccharide, which consists of galactose and N-acetylgalactosamine, is unknown. Two glycosyltransferase-like genes encoding multifunctional proteins, each with predicted features of a heteropolysaccharide synthase, were identified in the Dictyostelium discoideum genome. pgtB and pgtC transcripts were modestly upregulated during early development, and pgtB was further intensely upregulated at the time of heteropolysaccharide accumulation. Disruption of either gene reduced synthase-like activity and blocked heteropolysaccharide formation, based on loss of cytological labeling with a lectin and absence of component sugars after acid hydrolysis. Cell mixing experiments showed that heteropolysaccharide expression is spore cell autonomous, suggesting a physical association with other coat molecules during assembly. Mutant coats expressed reduced levels of crystalline cellulose based on chemical analysis after acid degradation, and cellulose was heterogeneously affected based on flow cytometry and electron microscopy. Mutant coats also contained elevated levels of selected coat proteins but not others and were sensitive to shear. Mutant spores were unusually susceptible to hypertonic collapse and damage by detergent or hypertonic stress. Thus, the heteropolysaccharide is essential for spore integrity, which can be explained by a role in the formation of crystalline cellulose and regulation of the protein content of the coat.
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Affiliation(s)
- Christopher M West
- Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA.
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20
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Atkinson SD, Bartholomew JL. Alternate spore stages of Myxobilatus gasterostei, a myxosporean parasite of three-spined sticklebacks (Gasterosteus aculeatus) and oligochaetes (Nais communis). Parasitol Res 2008; 104:1173-81. [PMID: 19107523 DOI: 10.1007/s00436-008-1308-6] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2008] [Accepted: 12/02/2008] [Indexed: 11/29/2022]
MESH Headings
- Animals
- Cluster Analysis
- DNA, Protozoan/chemistry
- DNA, Protozoan/genetics
- DNA, Ribosomal/chemistry
- DNA, Ribosomal/genetics
- Female
- Genes, rRNA
- Life Cycle Stages
- Male
- Molecular Sequence Data
- Myxozoa/cytology
- Myxozoa/isolation & purification
- Myxozoa/physiology
- Oligochaeta/parasitology
- Oregon
- Parasitic Diseases, Animal/parasitology
- Phylogeny
- RNA, Protozoan/genetics
- RNA, Ribosomal, 18S/genetics
- Sequence Analysis, DNA
- Smegmamorpha/parasitology
- Spores, Protozoan/cytology
- Spores, Protozoan/physiology
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21
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Jelínek J, Salát J, Sak B, Kopecký J. Effects of interferon gamma and specific polyclonal antibody on the infection of murine peritoneal macrophages and murine macrophage cell line PMJ2-R with Encephalitozoon cuniculi. Folia Parasitol (Praha) 2007; 54:172-176. [PMID: 19245188] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Experimental activation of peritoneal macrophages by interferon gamma (IFN-gamma) resulted in the inhibition of Encephalitozoon cuniculi replication. However, E. cuniculi could replicate either in a non-activated cell line of murine macrophages PMJ2-R or in IFN-gamma-activated PMJ2-R cells. Moreover, activation with IFN-gamma led to faster replication of E. cuniculi in these cells. Opsonisation of E. cuniculi spores with anti-E. cuniculi polyclonal antibody did not affect E. cuniculi replication in both, non-activated and activated murine macrophages. In contrast, opsonisation of E. cuniculi spores caused the most effective replication of E. cuniculi in activated PMJ2-R cells. However, production of nitric oxide by these cells was significantly more intensive than that in non-activated, infected cells, where the parasite replicated to a much lesser extent. Our results support the hypothesis that E. cuniculi uses phagocytosis for the infection of host cells. They also indicate that the mechanism by which spores of E. cuniculi are killed by macrophages is not dependent on nitric oxide and they reveal that PMJ2-R cells cannot substitute peritoneal murine macrophages in immunological studies on E. cuniculi.
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Affiliation(s)
- Jirí Jelínek
- Institute of Parasitology, Biology Centre, Academy of Sciences of the Czech Republic, Branisovská 31,370 05 Ceské Budĕjovice, Czech Republic.
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22
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Kinseth MA, Anjard C, Fuller D, Guizzunti G, Loomis WF, Malhotra V. The Golgi-Associated Protein GRASP Is Required for Unconventional Protein Secretion during Development. Cell 2007; 130:524-34. [PMID: 17655921 DOI: 10.1016/j.cell.2007.06.029] [Citation(s) in RCA: 187] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2007] [Revised: 05/17/2007] [Accepted: 06/15/2007] [Indexed: 10/23/2022]
Abstract
During Dictyostelium development, prespore cells secrete acyl-CoA binding protein (AcbA). Upon release, AcbA is processed to generate a peptide called spore differentiation factor-2 (SDF-2), which triggers terminal differentiation of spore cells. We have found that cells lacking Golgi reassembly stacking protein (GRASP), a protein attached peripherally to the cytoplasmic surface of Golgi membranes, fail to secrete AcbA and, thus, produce inviable spores. Surprisingly, AcbA lacks a signal sequence and is not secreted via the conventional secretory pathway (endoplasmic reticulum-Golgi-cell surface). GRASP is not required for conventional protein secretion, growth, and the viability of vegetative cells. Our findings reveal a physiological role of GRASP and provide a means to understand unconventional secretion and its role in development.
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Affiliation(s)
- Matthew A Kinseth
- Cell and Developmental Biology, Division of Biological Sciences, University of California, San Diego, La Jolla, CA 92093, USA
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23
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Zhang F, Lu X, Kumar VS, Zhu H, Chen H, Chen Z, Hong J. Effects of a novel anti-exospore monoclonal antibody on microsporidialNosema bombycisgermination and reproductionin vitro. Parasitology 2007; 134:1551-8. [PMID: 17577423 DOI: 10.1017/s0031182007002934] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
SUMMARYA monoclonal antibody (mAb) 3C2, against an exospore protein of the microsporidiumNosema bombycis(N. bombycis) was prepared, and its effects on microsporidial germination and reproductionin vitrowere studied. MAb 3C2 was effective in inhibiting the germination and subsequent infection ofBombyx moricells compared to the control mAb. The antigen was isolated by 2-dimensional gel electrophoresis. Immunoblotting revealed it to be an 84 kDa protein corresponding to pI (7·2) on the 2-D gel. The present results suggest that the antibodies can be used for diagnostic purposes and for developing new therapeutic strategies in controlling microsporidian diseases.
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MESH Headings
- Animals
- Antibodies, Monoclonal/immunology
- Antibodies, Monoclonal/pharmacology
- Antibodies, Protozoan/immunology
- Antibodies, Protozoan/pharmacology
- Antigens, Protozoan/chemistry
- Antigens, Protozoan/immunology
- Cells, Cultured
- Female
- Mice
- Mice, Inbred BALB C
- Nosema/drug effects
- Nosema/growth & development
- Nosema/physiology
- Reproduction/drug effects
- Reproduction/physiology
- Spores, Protozoan/drug effects
- Spores, Protozoan/immunology
- Spores, Protozoan/physiology
- Time Factors
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Affiliation(s)
- F Zhang
- Laboratory of Invertebrate Pathology, Zhejiang University, Hangzhou 310029, China
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24
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Abstract
A number of complex processes are involved in Eimeria spp. survival, including control of sporulation, intracellular invasion, evasion of host immune responses, successful reproduction, and nutrition. Proteases have been implicated in many of these processes, but the occurrence and functions of serine proteases have not been characterized. Bioinformatic analysis suggests that the Eimeria tenella genome contains several serine proteases that lack homology to trypsin. Using RT-PCR, a gene encoding a subtilisin-like and a rhomboid protease-like serine protease was shown to be developmentally regulated, both being poorly expressed in sporozoites (SZ) and merozoites (MZ). Casein substrate gel electrophoresis of oocyst extracts during sporulation demonstrated bands of proteolytic activity with relative molecular weights (Mr) of 18, 25, and 45 kDa that were eliminated by coincubation with serine protease inhibitors. A protease with Mr of 25 kDa was purified from extracts of unsporulated oocysts by a combination of affinity and anion exchange chromatography. Extracts of SZ contained only a single band of inhibitor-sensitive proteolytic activity at 25 kDa, while the pattern of proteases from extracts of MZ was similar to that of oocysts except for the occurrence of a 90 kDa protease, resistant to protease inhibitors. Excretory-secretory products (ESP) from MZ contained AEBSF (4-[2-Aminoethyl] benzenesulphonyl fluoride)-sensitive protease activity with a specific activity about 10 times greater than that observed in MZ extracts. No protease activity was observed in the ESP from SZ. Pretreatment of SZ with AEBSF significantly reduced SZ invasion and the release of the microneme protein, MIC2. The current results suggest that serine proteases are present in all the developmental stages examined.
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Affiliation(s)
- R H Fetterer
- Animal Parasitic Diseases Laboratory, Animal and Natural Resources institute, United States Department of Agriculture, Henry A. Wallace Beltsville Agricultural Research Center, Beltsville, Maryland 20705, USA.
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25
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Alvarez-Curto E, Saran S, Meima M, Zobel J, Scott C, Schaap P. cAMP production by adenylyl cyclase G induces prespore differentiation in Dictyostelium slugs. Development 2007; 134:959-66. [PMID: 17267449 PMCID: PMC2176081 DOI: 10.1242/dev.02775] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Encystation and sporulation are crucial developmental transitions for solitary and social amoebae, respectively. Whereas little is known of encystation, sporulation requires both extra- and intracellular cAMP. After aggregation of social amoebae, extracellular cAMP binding to surface receptors and intracellular cAMP binding to cAMP-dependent protein kinase (PKA) act together to induce prespore differentiation. Later, a second episode of PKA activation triggers spore maturation. Adenylyl cyclase B (ACB) produces cAMP for maturation, but the cAMP source for prespore induction is unknown. We show that adenylyl cyclase G (ACG) protein is upregulated in prespore tissue after aggregation. acg null mutants show reduced prespore differentiation, which becomes very severe when ACB is also deleted. ACB is normally expressed in prestalk cells, but is upregulated in the prespore region of acg null structures. These data show that ACG induces prespore differentiation in wild-type cells, with ACB capable of partially taking over this function in its absence.
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Affiliation(s)
| | | | | | | | | | - Pauline Schaap
- corresponding author, E-mail:, Phone: 44 1382 388078, Fax: 44 1382 345386
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26
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McGurk C, Morris DJ, Adams A. Sequential development of Buddenbrockia plumatellae (Myxozoa: Malacosporea) within Plumatella repens (Bryozoa: Phylactolaemata). Dis Aquat Organ 2006; 73:159-69. [PMID: 17260835 DOI: 10.3354/dao073159] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
Colonies of the freshwater bryozoan Plumatella repens collected from a river in the UK were found to be infected with the myxozoan parasite Buddenbrockia plumatellae following laboratory maintenance. Optimisation of the bryozoan diet allowed maintenance of infected colonies for 90 d, permitting observation by light and electron microscopy of the sequential parasitic developmental cycle. Parasite stages were associated with host peritoneum, identifying the primary developmental phase. The association of B. plumatellae cells with peritoneal basal lamina and morphological similarities between parasite and host suggested that the parasite remodelled host tissue. Progressive expansion and elongation of individual parasites led to the release of freely floating vermiform stages within the host coelomic cavities. Within these 'worms', intraluminal masses developed, resulting in the formation of spores. Upon maturation, the 'worms' ruptured, releasing many spores within the host that were subsequently discharged. Although parasitism led to increased bryozoan fragmentation and lowered statoblast production, some colonies did survive, resulting in repeated waves of infection. Long-term laboratory maintenance of infected bryozoan colonies could provide a means of maintaining B. plumatellae for study until the full life cycle is ascertained.
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Affiliation(s)
- Charles McGurk
- Institute of Aquaculture, University of Stirling, Stirling FK9 4LA, UK.
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27
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Holzer AS, Blasco-Costa I, Sarabeev VL, Ovcharenko MO, Balbuena JA. Kudoa trifolia sp. n. - molecular phylogeny suggests a new spore morphology and unusual tissue location for a well-known genus. J Fish Dis 2006; 29:743-55. [PMID: 17169107 DOI: 10.1111/j.1365-2761.2006.00770.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
A new species of myxozoan, Kudoa trifolia sp. n., was found in various organs of the golden grey mullet, Liza aurata (Risso), and the thinlip mullet, L. ramada (Risso), from the western Mediterranean. Spores developed in subspherical plasmodia of 0.28-1 mm diameter within connective tissue, predominantly in the spleen, the outer wall of the gall bladder and the gut, the mesenteries and occasionally also in the gills. The spores of K. trifolia differ from the commonly known shape of Kudoa by considerable enlargement of one of the four valve cells, thus forming a 'spore body', which contains the major part of the binucleate sporoplasm. Scanning electron microscopy of the spores revealed the presence of grape-like appendages, which occur in bundles terminally on the valve cells. Phylogenetic analysis based on the 18S rDNA sequence of K. trifolia showed that this species is deeply embedded in the genus Kudoa despite its aberrant morphology and host tissue location. This suggests important amendments to the morphological diagnosis of the genus Kudoa.
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Affiliation(s)
- A S Holzer
- Cavanilles Institute of Biodiversity and Evolutionary Biology, University of Valencia, Valencia, Spain.
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28
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Yokoyama H, Kim JH, Urawa S. Differences in host selection of actinospores of two myxosporeans, Myxobolus arcticus and Thelohanellus hovorkai. J Parasitol 2006; 92:725-9. [PMID: 16995388 DOI: 10.1645/ge-831r.1] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
We investigated the host selection mechanism of actinospore stages of 2 myxosporeans, Myxobolus arcticus and Thelohanellus hovorkai, infecting masu salmon (Oncorhynchus masou) and common carp (Cyprinus carpio), respectively. Discharge of the polar filaments and sporoplasm release by M. arcticus actinospores occurred within the first 5 min of exposure to skin mucus of masu salmon. The actinospores also reacted to the mucus of nonsusceptible fish, i.e., sockeye salmon (Oncorhynchus nerka) and goldfish (Carassius auratus), although the reactivity was comparatively lower. After exposure of masu, and sockeye and chum salmon (Oncorhynchus keta) to M. arcticus actinospores, the penetration of sporoplasms was observed in the fins and gills of masu and sockeye salmon to a similar extent and to a lesser extent in chum salmon. Thelohanellus hovorkai actinospores exhibited a slow response of sporoplasm release to common carp mucus as well as penetration into the gills of common carp. Neither chemoresponse to mucus of nonsusceptible fish (goldfish and sockeye salmon) nor sporoplasm invasion in goldfish was observed for T. hovorkai actinospores. These results indicate notable differences in the host selection at the time of entry between M. arcticus and T. hovorkai; the former responds quickly to fish mucus with low host specificity, whereas the latter was highly host specific in a dilatory reaction.
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Affiliation(s)
- Hiroshi Yokoyama
- Department of Aquatic Bioscience, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo, Tokyo 113-8657, Japan.
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29
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Browne RK, Li H, Vaughan M. Sexually mediated shedding of Myxobolus fallax spores during spermiation of Litoria fallax (anura). Dis Aquat Organ 2006; 72:71-5. [PMID: 17067075 DOI: 10.3354/dao072071] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Myxobolus fallax (Myxosporea) infects the testes of the dwarf green tree frog Litoria fallax without apparently affecting the host's health, behavior, or testicular sperm numbers or quality. We investigated the shedding M. fallax spores and the relationship between M. fallax infection and fertility in L. fallax. During natural spawning, comparisons were made between the prevalence and intensity of M. fallax infection, spore shedding, and fertilization rates. During the hormonal induction of spermiation, comparisons were made between the prevalence and intensity of M. fallax infection, and the number of sperm and spores shed. During natural spawning, the prevalence or intensity of infection or spore shedding did not affect fertility. Spermiation and spore shedding was induced in 10 males by the administration of human chorionic gonadotrophin, with 10 controls. Histology showed that all 10 males were infected by M. fallax. The controls shed no sperm or spores. Nine infected males shed sperm 3 h post-administration (PA), and 3 of these also shed spores. Only the 3 males that shed sperm and spores at 3 h PA also shed sperm at 6 h PA, at which time they also shed spores. In total, the 3 males that shed spores gave higher sperm numbers than the 6 males that did not shed spores. Overall, these results show that the shedding of M. fallax spores is sexually mediated through reproductive hormones without affecting fertility.
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Affiliation(s)
- Robert K Browne
- Department of Biological Sciences, University of Newcastle, University Drive, Callaghan, New South Wales, Australia.
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Bartholomew JL, Atkinson SD, Hallett SL. INVOLVEMENT OF MANAYUNKIA SPECIOSA (ANNELIDA: POLYCHAETA: SABELLIDAE) IN THE LIFE CYCLE OF PARVICAPSULA MINIBICORNIS, A MYXOZOAN PARASITE OF PACIFIC SALMON. J Parasitol 2006; 92:742-8. [PMID: 16995391 DOI: 10.1645/ge-781r.1] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
A coelomic myxozoan infection was detected in freshwater polychaetes, Manayunkia speciosa from the Klamath River, Oregon/California, a site enzootic for the myxozoan parasites Ceratomyxa shasta and Parvicapsula minibicornis. The tetractinomyxon type actinospores had a near-spherical spore body 7.9 x 7.1 microm, with 3 spherical, protruding polar capsules, no valve cell processes, and a binucleate sporoplasm. Parvicapsula minibicornis-specific primers Parvi1f and Parvi2r amplified DNA from infected polychaetes in a polymerase chain reaction (PCR) assay. The small subunit 18S rRNA gene of the spores was sequenced (GenBank DQ231038) and was a 99.7% match with the sequence for P. minibicornis myxospore stage in GenBank (AF201375). Chinook salmon (Oncorhynchus tshawytscha) exposed to a dose of 1,000 actinospores per fish tested PCR positive for P. minibicornis at 14 wk postinfection and presporogonic stages were detected in the kidney tubules by histology at 20 wk. This life cycle is 1 of only about 30 known from more than 1,350 myxozoan species, and only the second known from a freshwater polychaete.
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Affiliation(s)
- Jerri L Bartholomew
- Center for Fish Disease Research, Department of Microbiology, Nash Hall 220, Oregon State University, Corvallis, Oregon 97331, USA.
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31
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Carnegie RB, Burreson EM, Hine PM, Stokes NA, Audemard C, Bishop MJ, Peterson CH. Bonamia perspora n. sp. (Haplosporidia), a Parasite of the Oyster Ostreola equestris, is the First Bonamia Species Known to Produce Spores. J Eukaryot Microbiol 2006; 53:232-45. [PMID: 16872291 DOI: 10.1111/j.1550-7408.2006.00100.x] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Examination of the oyster Ostreola equestris as a potential reservoir host for a species of Bonamia discovered in Crassostrea ariakensis in North Carolina (NC), USA, revealed a second novel Bonamia sp. Histopathology, electron microscopy, and molecular phylogenetic analysis support the designation of a new parasite species, Bonamia perspora n. sp., which is the first Bonamia species shown to produce a typical haplosporidian spore with an orifice and hinged operculum. Spores were confirmed to be from B. perspora by fluorescent in situ hybridization. Bonamia perspora was found at Morehead City and Wilmington, NC, with an overall prevalence of 1.4% (31/2,144). Uninucleate, plasmodial, and sporogonic stages occurred almost exclusively in connective tissues; uninucleate stages (2-6 microm) were rarely observed in hemocytes. Spores were 4.3-6.4 microm in length. Ultrastructurally, uninucleate, diplokaryotic, and plasmodial stages resembled those of other spore-forming haplosporidians, but few haplosporosomes were present, and plasmodia were small. Spore ornamentation consisted of spore wall-derived, thin, flat ribbons that emerged haphazardly around the spore, and which terminated in what appeared to be four-pronged caps. Number of ribbons per spore ranged from 15 to 30, and their length ranged from 1.0 to 3.4 microm. Parsimony analysis identified B. perspora as a sister species to Bonamia ostreae.
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Affiliation(s)
- Ryan B Carnegie
- Virginia Institute of Marine Science, College of William and Mary, Gloucester Point, Virginia 23062, USA.
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32
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Abstract
Myxozoans of the genus Kudoa are widespread parasites of marine fishes and primarily infect the body musculature of their hosts. Although Kudoa species are not usually associated with host mortality, some do form macroscopic cysts in the tissue and some are associated with post mortem tissue degradation. This is of concern to commercial fisheries as fillets may be unmarketable due to these infections. Because different species of Kudoa have different effects on their hosts, it is important to correctly identify species with epidemiological relevance, distinguishing those that are benign from those that are associated with these detrimental effects. Using morphological and molecular analyses, we identified K. alliaria infecting Argentinian hoki Macruronus magellanicus. Comparisons of the small subunit ribosomal DNA sequence revealed that K. alliaria is genetically very similar to K. rosenbuschi. Furthermore, there is significant overlap in myxospore dimensions between descriptions of these 2 Kudoa species as well as those of other Patagonian fishes. Thus, without careful examination of the myxospore dimensions, it may be difficult to identify these species on a routine basis. It is critical to accurately identify K. alliaria as, unlike K. rosenbuschi, it is not associated with tissue degradation. Ambiguities in some species descriptions highlight the need for thorough morphological analyses accompanied by molecular comparisons to clarify the species boundaries between Kudoa parasites of Patagonian fishes.
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Affiliation(s)
- Christopher M Whipps
- Center for Fish Disease Research, Department of Microbiology, Oregon State University, Corvallis 97331-3404, USA.
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33
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Abstract
Our previous investigation demonstrated the expression in Eimeria tenella sporulated oocysts of an aminopeptidase (AP) with strong homology to AP N. To further understand the role of proteases during development, we investigated the molecular and biochemical properties of E. tenella AP. Greater than 95% AP activity was present in a soluble extract during sporulation of oocysts with highest activity in fully sporulated oocysts. The AP activity was inhibited by the AP inhibitors bestatin and 1,6-phenanthroline, but not by serine protease inhibitors. The AP had specificity for synthetic endopeptidase substrates that contain arginine, alanine, or glycine at the N terminus. Partial purification of the enzyme yielded a major protein band with an Mr of about 106 kDa and an isoelectric point (Ip) of 5.1. Reverse transcription-polymerase chain reaction indicated that the gene for AP is expressed during sporulation, but expression is absent or greatly reduced in the sporozoites and merozoites. On the basis of the deduced gene structure, the predicted Mr is 110 kDa with a pI of 5.59. Database search indicates that the E. tenella AP shares significant homology with the AP from Apicomplexan taxa: Toxoplasma gondii, Cryptosporidium parvum, and Cryptosporidium hominis. Together, these results confirm the presence of a cytosolic AP related to AP N, which is expressed and active during sporulation of E. tenella oocysts.
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Affiliation(s)
- R H Fetterer
- Animal Parasitic Diseases Laboratory, Animal and Natural Resources Institute, United States Department of Agriculture, Henry A Wallace Beltsville Agricultural Research Center, Maryland 20705, USA.
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34
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Abstract
Anopheles culicifaciessensu lato comprises five sibling species. We report the isolation of an An. culicifacies species B strain which is completely refractory to Plasmodium vivax sporogonic development and partially refractory to P. falciparum. Parasite development in this strain is arrested by a melanotic encapsulation mechanism in the mid-gut. We compare the infectivity of this refractory strain and four other species B strains from different epidemiological zones of India with P. vivax in the laboratory.
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Affiliation(s)
- T Adak
- National Institute of Malaria Research, Delhi, India.
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35
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Sokolova YY, Lange CE, Fuxa JR. Development, ultrastructure, natural occurrence, and molecular characterization of Liebermannia patagonica n. g., n. sp., a microsporidian parasite of the grasshopper Tristira magellanica (Orthoptera: Tristiridae). J Invertebr Pathol 2006; 91:168-82. [PMID: 16524588 DOI: 10.1016/j.jip.2006.01.003] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2005] [Revised: 01/18/2006] [Accepted: 01/25/2006] [Indexed: 11/28/2022]
Abstract
A new microsporidium, Liebermannia patagonica n. gen., n. sp., is described from midgut and gastric caecum epithelial cells of Tristira magellanica, an apterous grasshopper species of southern Patagonia, Argentina. L.patagonica is diplokaryotic, apansporoblastic, homosporous, and polysporoblastic. Transitional (from merogony to sporogony) stages and sporonts of L. patagonica were surrounded by host rough endoplasmic reticulum. The ovocylindrical spores measured 2.9 +/- 0.09 x 1.2 +/- 0.04 microm (fresh, n = 50), and they had an isofilar polar filament of only three coils and a cluster of tubules instead of a classical posterior vacuole. Prevalence was high (up to 80.6%) at the type locality for the four years sampled . Maximum likelihood , neighbor joining, maximum parismony analyses of the small submit rDNA all placed L.patagonica(Accession No. DQ 239917) in one with Orthosomella operophterae.
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MESH Headings
- Animals
- DNA, Ribosomal
- Grasshoppers/parasitology
- Host-Parasite Interactions
- Microscopy, Electron, Transmission
- Microsporidia, Unclassified/classification
- Microsporidia, Unclassified/genetics
- Microsporidia, Unclassified/growth & development
- Microsporidia, Unclassified/isolation & purification
- Microsporidia, Unclassified/physiology
- Microsporidia, Unclassified/ultrastructure
- Molecular Sequence Data
- Phylogeny
- Spores, Protozoan/genetics
- Spores, Protozoan/physiology
- Spores, Protozoan/ultrastructure
- Tropism
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Affiliation(s)
- Yuliya Y Sokolova
- Institute of Cytology, Russian Academy of Sciences, 4 Tikhoretsky Ave., 194064 St. Petersburg, Russia.
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36
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Morris DJ, Adams A. Transmission of freshwater myxozoans during the asexual propagation of invertebrate hosts. Int J Parasitol 2006; 36:371-7. [PMID: 16373070 DOI: 10.1016/j.ijpara.2005.10.009] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2005] [Revised: 10/26/2005] [Accepted: 10/28/2005] [Indexed: 11/21/2022]
Abstract
The phylum Myxozoa contains over 1350 species almost all of which are considered to be obligate parasites of aquatic animals. The phylum is composed of two classes, the Myxosporea and the Malacosporea, species of which are important pathogens responsible for severe economic losses in cultured fisheries. The life cycles of freshwater Myxozoa are believed to involve horizontal, indirect transmission, involving an invertebrate (oligochaetes or bryozoans) and a vertebrate host (fish or amphibians). Here, we describe myxozoan propagation through the fragmentation of invertebrate hosts to form new infected individuals. The two hosts examined are an oligochaete Lumbriculus variegatus infected with an unidentified myxosporean (Triactinomyxon sp.) and the bryozoan Fredericella sultana infected with the malacosporean Tetracapsuloides bryosalmonae which causes proliferative kidney disease, a major constraint of the European rainbow trout industry. Such intra-clonal propagation is a novel form of vertical transmission that is likely to be widespread within the Myxozoa and could form an important method by which some of these parasites maintain and proliferate within the aquatic environment.
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Affiliation(s)
- D J Morris
- Institute of Aquaculture, University of Stirling, Stirling, FK9 4LA Scotland, UK.
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37
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Arai A, Goto Y, Hasegawa A, Hosaka K, Kikuchi H, Oshima Y, Tanaka S, Kubohara Y. Dictyopyrones, novel alpha-pyronoids isolated from Dictyostelium spp., promote stalk cell differentiation in Dictyostelium discoideum. Differentiation 2006; 73:377-84. [PMID: 16219041 DOI: 10.1111/j.1432-0436.2005.00039.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Dictyopyrones A and B (DpnA and B), whose function(s) is not known, were isolated from fruiting bodies of Dictyostelium discoideum. In the present study, to assess their function(s), we examined the effects of Dpns on in vitro cell differentiation in D. discoideum monolayer cultures with cAMP. Dpns at 1-20 microM promoted stalk cell formation to some extent in the wild-type strain V12M2. Although Dpns by themselves could hardly induce stalk cell formation in a differentiation-inducing factor (DIF)-deficient strain HM44, both of them dose-dependently promoted DIF-1-dependent stalk cell formation in the strain. In the sporogenous strain HM18, Dpns at 1-20 microM suppressed spore formation and promoted stalk cell formation in a dose-dependent manner. Analogs of Dpns were less effective in affecting cell differentiation in both HM44 and HM18 cells, indicating that the activity of Dpns should be chemical structure specific. It was also shown that DpnA at 2-20 microM dose-dependently suppressed spore formation induced with 8-bromo cAMP and promoted stalk cell formation in V12M2 cells. Interestingly, it was shown by the use of RT-PCR that DpnA at 10 microM slightly promoted both prespore- and prestalk-specific gene expressions in an early phase of V12M2 and HM18 in vitro differentiation. The present results suggest that Dpns may have functions (1) to promote both prespore and prestalk cell differentiation in an early stage of development and (2) to suppress spore formation and promote stalk cell formation in a later stage of development in D. discoideum.
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Affiliation(s)
- Akiko Arai
- Department of Basic Sciences for Medicine, Gunma University School of Health Sciences, Maebashi 371-8514, Japan
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38
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Beauchamp KA, El-Matbouli M, Gay M, Georgiadis MP, Nehring RB, Hedrick RP. The effect of cohabitation of Tubifex tubifex (Oligochaeta: Tubificidae) populations on infections to Myxobolus cerebralis (Myxozoa: Myxobolidae). J Invertebr Pathol 2006; 91:1-8. [PMID: 16321396 DOI: 10.1016/j.jip.2005.08.006] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2005] [Revised: 07/29/2005] [Accepted: 08/08/2005] [Indexed: 11/16/2022]
Abstract
The competitive interactions between susceptible and resistant Tubifex tubifex (Oligochaeta: Tubificidae) exposed to Myxobolus cerebralis (Myxozoa: Myxobolidae) infections were investigated in two laboratory trials. Competition was assessed by the total parasite production over the course of the trials in mixed and pure cultures of M. cerebralis exposed worms, and by the genetic analyses of worms from the control and experimental groups at the beginning and end of the experiments. Mixed cultures of resistant and susceptible worms showed a 70% reduction in production of parasites released when compared with pure cultures of susceptible worms. In studies with laboratory and field-collected oligochaetes the mixed cultures at the end of the cohabitation experiments were dominated by resistant Tubifex from lineage V (HB strain) this strain of Tubifex has a competitive advantage over worms from other lineages. The results of this study suggest that certain species of Tubifex may be dead-end hosts to M. cerebralis by absorbing or inactivating the parasite and may also show greater survival compared to susceptible oligochaetes in certain whirling disease enzootic habitats.
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Affiliation(s)
- Katherine A Beauchamp
- Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California, Davis, CA 95616, USA.
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39
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Leitch GJ, Ward TL, Shaw AP, Newman G. Apical spore phagocytosis is not a significant route of infection of differentiated enterocytes by Encephalitozoon intestinalis. Infect Immun 2005; 73:7697-704. [PMID: 16239574 PMCID: PMC1273909 DOI: 10.1128/iai.73.11.7697-7704.2005] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Encephalitozoon intestinalis is a microsporidian species that infects the intestinal mucosal epithelium, primarily in immunodeficient individuals. The present study employed undifferentiated and differentiated human colonic carcinoma cell lines to determine if this parasite species infected polarized epithelial cells by spore phagocytosis or by impalement with the deployed spore polar tube. Apical surface spore attachment differed between cell lines such that SW480>HT-29>Caco-2>HCT-8, with attachment being greater to undifferentiated Caco-2 cells than differentiated cells and greater to partially differentiated HCT-8 cells than differentiated HCT-8 cells. Attachment was inhibited by chondroitin sulfate A, suggesting that it was mediated by host cell sulfated glycoaminoglycans. Infection rates 3 days postinfection paralleled spore attachment in the various cell lines. The undifferentiated cell line SW480 and undifferentiated Caco-2 and HCT-8 cells exhibited modest spore phagocytosis while the more differentiated cell line HT29 and differentiated Caco-2 and HCT-8 cells did not. All cell lines were impaled by the polar tubes of germinating spores. When normalized to the number of spores attached to the apical membrane, such impalement was greatest in the more differentiated Caco-2 and HCT-8 cells. The host cell apical surface influenced parasite spore germination, as in populations of large undifferentiated Caco-2 cells to which >3 spores had attached, the frequency distribution of the percentages of spores germinated per cell was bimodal, indicating that the surface of some cells favored germination, while others did not. This study suggests that phagocytosis is not a biologically significant mode of infection in differentiated intestinal epithelial cells.
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Affiliation(s)
- Gordon J Leitch
- Department of Physiology, Morehouse School of Medicine, 720 Westview Dr., Atlanta, GA 30310, USA.
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40
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Abstract
Dictyostelium discoideum is a eukaryotic amoeba, which, when starvation is imminent, aggregates to form fruiting bodies consisting of a stalk of reproductively dead cells that supports spores. Because different clones may be involved in such aggregations, cheater strategies may emerge that allocate a smaller fraction of cells to stalk formation, thus gaining a reproductive advantage. In this paper, we model the evolutionary dynamics of allocation strategies in Dictyostelium under the realistic assumption that the number of clones involved in aggregations follows a random distribution. By determining the full course of evolutionary dynamics, we show that evolutionary branching in allocation strategies may occur, resulting in dimorphic populations that produce stalkless and stalked fruiting bodies. We also demonstrate that such dimorphisms are more likely to emerge when the variation in the number of clones involved in aggregations is large.
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Affiliation(s)
- A Brännström
- Adaptive Dynamics Network, International Institute for Applied Systems Analysis, Schlossplatz 1, Laxenburg A - 2361, Austria.
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41
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Kim BJ, Choi CH, Lee CH, Jeong SY, Kim JS, Kim BY, Yim HS, Kang SO. Glutathione is required for growth and prespore cell differentiation in Dictyostelium. Dev Biol 2005; 284:387-98. [PMID: 15993406 DOI: 10.1016/j.ydbio.2005.05.034] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2004] [Revised: 03/30/2005] [Accepted: 05/25/2005] [Indexed: 01/10/2023]
Abstract
Glutathione (GSH) is the most abundant non-protein thiol in eukaryotic cells and acts as reducing equivalent in many cellular processes. We investigated the role of glutathione in Dictyostelium development by disruption of gamma-glutamylcysteine synthetase (GCS), an essential enzyme in glutathione biosynthesis. GCS-null strain showed glutathione auxotrophy and could not grow in medium containing other thiol compounds. The developmental progress of GCS-null strain was determined by GSH concentration contained in preincubated media before development. GCS-null strain preincubated with 0.2 mM GSH was arrested at mound stage or formed bent stalk-like structure during development. GCS-null strain preincubated with more than 0.5 mM GSH formed fruiting body with spores, but spore viability was significantly reduced. In GCS-null strain precultured with 0.2 mM GSH, prestalk-specific gene expression was delayed, while prespore-specific gene and spore-specific gene expressions were not detected. In addition, GCS-null strain precultured with 0.2 mM GSH showed prestalk tendency and extended G1 phase of cell cycle. Since G1 phase cells at starvation differentiate into prestalk cells, developmental defect of GCS-null strain precultured with 0.2 mM GSH may result from altered cell cycle. These results suggest that glutathione itself is essential for growth and differentiation to prespore in Dictyostelium.
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Affiliation(s)
- Beom-Jun Kim
- Laboratory of Biophysics, School of Biological Sciences, and Institute of Microbiology, Seoul National University, Seoul 151-742, Republic of Korea
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42
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Abstract
Cyclic AMP metabolism is essential for the survival of the social amoebae Dictyostelium discoideum. Three distinct adenylyl cyclases are expressed and required for the normal development of this simple eukaryote. The adenylyl cyclase expressed during aggregation, ACA, is related to the mammalian and Drosophila G protein-coupled enzymes and is responsible for the synthesis of cAMP that is required for cell-cell signaling in early development. ACB harbors histidine kinase and response-regulator domains and is required for terminal differentiation. Finally, the adenylyl cyclase expressed during germination, ACG, acts as an osmosensor and is involved in controlling spore germination. Together, these enzymes generate the various levels of cAMP that are required for D. discoideum to transition from uni- to multi-cellularity. This review will highlight the properties of these enzymes and describe the signaling cascades that lead to their activation.
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Affiliation(s)
- Paul W Kriebel
- Laboratory of Cellular and Molecular Biology, National Cancer Institutes of Health, 37 Convent Drive, Bethesda, MD 20892-4256, USA
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43
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Abstract
The differentiation-inducing signals (DIFs) currently known in Dictyostelium appear unable to account for the full diversity of cell types produced in development. To search for new signals, we analyzed the differentiation in monolayers of cells expressing prestalk (ecmAO, ecmA, ecmO, ecmB and cAR2) and prespore (psA) markers. Expression of each marker drops off as the cell density is reduced, suggesting that cell interaction is required. Expression of each marker is inhibited by cerulenin, an inhibitor of polyketide synthesis, and can be restored by conditioned medium. However, the known stalk-inducing polyketide, DIF-1, could not replace conditioned medium and induce the ecmA or cAR2 prestalk markers, suggesting that they require different polyketide inducers. Polyketide production by fungi is stimulated by cadmium ions, which also dramatically stimulates differentiation in Dictyostelium cell cultures and the accumulation of medium factors. Factors produced with cadmium present were extracted from conditioned medium and fractionated by HPLC. A new factor inducing prespore cell differentiation, called PSI-2, and two inducing stalk cell differentiation (DIFs 6 and 7) were resolved. All are distinct from currently identified factors. DIF-6, but not DIF-7 or PSI-2, appears to have an essential carbonyl group. Thus Dictyostelium may use extensive polyketide signaling in its development.
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44
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Vizoso DB, Lass S, Ebert D. Different mechanisms of transmission of the microsporidium Octosporea bayeri: a cocktail of solutions for the problem of parasite permanence. Parasitology 2005; 130:501-9. [PMID: 15991493 DOI: 10.1017/s0031182004006699] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Periods of low host density impose a constraint on parasites with direct transmission, challenging their permanence in the system. The microsporidium Octosporea bayeri faces such constraint in a metapopulation of its host, the cladoceran Daphnia magna, where ponds frequently lose their host population due to ponds drying out in summer and freezing in winter. We conducted experiments aimed to investigate the mechanisms of transmission of O. bayeri, and discuss how these mechanisms could contribute to the parasite's permanence in the system. Spores accumulate in the fat cells and the ovaries of the host, and vary in morphology, possibly corresponding to 3 different spore types. Horizontal transmission occurred through the release of spores from dead hosts, with the proportion of infected hosts depending on the spore dose. Further, spores are able to persist outside the host both in dry and wet conditions. Vertical transmission occurred to both parthenogenetic and sexual offspring. The former were invariably infected, while the sexually produced resting eggs (= ephippia) had a less efficient transmission. The parasite may be carried by the ephippia, and thus disperse to new ponds together with the host. Together, these mechanisms may allow the parasite to endure periods of harsh environmental conditions both outside and inside the host.
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Affiliation(s)
- D B Vizoso
- Département de Biologie, Unité d'Ecologie and Evolution, Université de Fribourg, Chemin du Musée 10, CH-1700 Fribourg, Switzerland.
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45
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Abstract
The microsporidium Octosporea bayeri can infect its host, the planktonic crustacean Daphnia magna, vertically and horizontally. The two routes differ greatly in the way the parasite leaves the harbouring host (transmission) and in the way it enters a new, susceptible host (infection). Infections resulting from each route may thus vary in the way they affect host and parasite life-histories and, subsequently, host and parasite fitness. We conducted a life-table experiment to compare D. magna infected with O. bayeri either horizontally or vertically, using three different parasite isolates. Both the infection route and the parasite isolate had significant effects on host life-history. Hosts matured at different ages depending on the parasite isolate, and at a size that varied with infection route. The frequency of host sterility and the host's life-time reproductive success were affected by both the infection route and the parasite isolate. The infection route also affected parasite life-history. The production of parasite spores was much higher in vertically than in horizontally infected hosts. We found a trade-off between the production of spores (the parasite's horizontal fitness component) and the production of infected host offspring (the parasite's vertical fitness component). This study shows that hosts and parasites can react plastically to different routes of infection, suggesting that ecological factors that may influence the relative importance of horizontal and vertical transmission can shape the evolution of host and parasite life histories, and, consequently, the evolution of virulence.
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Affiliation(s)
- D B Vizoso
- Département de Biologie, Unité d'Ecologie & Evolution, Université de Fribourg, Fribourg, Switzerland.
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46
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Abstract
Microsporidia are obligate intracellular opportunistic protists that infect a wide variety of animals, including humans, via environmentally resistant spores. Infection requires that spores be in close proximity to host cells so that the hollow polar tube can pierce the cell membrane and inject the spore contents into the cell cytoplasm. Like other eukaryotic microbes, microsporidia may use specific mechanisms for adherence in order to achieve target cell proximity and increase the likelihood of successful infection. Our data show that Encephalitozoon intestinalis exploits sulfated glycans such as the cell surface glycosaminoglycans (GAGs) in selection of and attachment to host cells. When exogenous sulfated glycans are used as inhibitors in spore adherence assays, E. intestinalis spore adherence is reduced by as much as 88%. However, there is no inhibition when nonsulfated glycans are used, suggesting that E. intestinalis spores utilize sulfated host cell glycans in adherence. These studies were confirmed by exposure of host cells to xylopyranoside, which limits host cell surface GAGs, and sodium chlorate, which decreases surface sulfation. Spore adherence studies with CHO mutant cell lines that are deficient in either surface GAGs or surface heparan sulfate also confirmed the necessity of sulfated glycans. Furthermore, when spore adherence is inhibited, host cell infection is reduced, indicating a direct association between spore adherence and infectivity. These data show that E. intestinalis specifically adheres to target cells by way of sulfated host cell surface GAGs and that this mechanism serves to enhance infectivity.
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Affiliation(s)
- J Russell Hayman
- Department of Microbiology, J.H. Quillen College of Medicine, East Tennessee State University, Box 70579, Johnson City, TN 37614, USA.
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47
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Xu Q, Ibarra M, Mahadeo D, Shaw C, Huang E, Kuspa A, Cotter D, Shaulsky G. Transcriptional transitions during Dictyostelium spore germination. Eukaryot Cell 2005; 3:1101-10. [PMID: 15470238 PMCID: PMC522591 DOI: 10.1128/ec.3.5.1101-1110.2004] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Many protozoa form spores in response to adversity; therefore, spore germination is a key process in their life cycle. Dictyostelium discoideum sporulates in response to starvation following a developmental program. Germination is characterized by two visible changes, spore swelling and the emergence of amoeba from the spore capsule. Several studies have indicated that an additional process termed spore activation is also required, but the physiological changes that characterize the three phases are largely uncharacterized. We used microarrays to monitor global transcriptional transitions as a surrogate measure of the physiological changes that occur during germination. Using two independent methods to induce germination, we identified changes in mRNA levels that characterized the germination process rather than changes that resulted from the induction method. We found that germination is characterized by three transitions. The first transition occurs during activation, while the spores appear dormant, the largest transition occurs when swelling begins, and the third transition occurs when emergence begins. These findings indicate that activation and swelling are not passive occurrences, such as dilution of inhibitors or spore rehydration, but are active processes that are accompanied by dramatic events in mRNA degradation and de novo transcription. These findings confirm and extend earlier reports that genes such as celA are regulated during spore germination. We also found by mutation analysis that the unconventional myosin gene myoI, which is induced during early germination, plays roles in the maintenance of dormancy and in spore swelling. This finding suggests that some of the observed transcriptional changes are required for spore germination.
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Affiliation(s)
- Qikai Xu
- Graduate Program in Structural and Computational Biology and Molecular Biophysics, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA
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Franzen C, Hartmann P, Salzberger B. Cytokine and nitric oxide responses of monocyte-derived human macrophages to microsporidian spores. Exp Parasitol 2005; 109:1-6. [PMID: 15639133 DOI: 10.1016/j.exppara.2004.10.001] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2004] [Revised: 07/30/2004] [Accepted: 10/14/2004] [Indexed: 11/24/2022]
Abstract
Microsporidia are obligate intracellular parasites that emerged as opportunistic pathogens since the onset of the AIDS pandemic. They are capable of disseminating through the body using macrophages as vehicles. We incubated human macrophages with spores of all three Encephalitozoon spp. as well as with Vittaforma corneae, and the number of intracellular spores per cell was determined by fluorescence microscopy. Cell culture supernatants were collected and the content of TNF-alpha, INF-gamma, IL-10, and of nitric oxide was determined. Microsporidian spores did not induce a nitric oxide response in macrophages and there was a negative correlation between the number of intracellular spores and the amount of nitric oxide. TNF-alpha, INF-gamma, and IL-10 increased after simulation of macrophages with microsporidian spores but for TNF-alpha and INF-gamma no clear correlation of cytokine levels with the number of intracellular spores could be observed. A modulation of the nitric oxide response by intracellular microsporidia may contribute to the survival of microsporidia within the macrophage by a mechanism yet unknown.
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Affiliation(s)
- C Franzen
- Department of Internal Medicine I, University of Regensburg, 93042 Regensburg, Germany.
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Zhang H, Gómez-García MR, Brown MRW, Kornberg A. Inorganic polyphosphate in Dictyostelium discoideum: influence on development, sporulation, and predation. Proc Natl Acad Sci U S A 2005; 102:2731-5. [PMID: 15701689 PMCID: PMC549442 DOI: 10.1073/pnas.0500023102] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Dictyostelium discoideum, a social slime mold that forms fruiting bodies with spores, depends on inorganic polyphosphate (poly P) for its cycles of development and for nutritional predation on bacteria. The synthesis of poly P, a polymer of tens or hundreds of phosphate residues linked by high energy, ATP-like bonds, is catalyzed in most bacteria by poly P kinase (PPK1). The eukaryote D. discoideum possesses a homolog of PPK1. We report here that mutants of D. discoideum PPK1 (DdPPK1) have reduced levels of poly P and are deficient in development. Fruiting bodies are smaller and produce fewer spores, which appear to germinate like the wild type (WT). The DdPPK1 mutant formed smaller plaques on bacterial lawns compared with those of the WT. Predation by D. discoideum, assessed by uptake and digestion of Klebsiella aerogenes, showed that fewer bacteria were taken up by the DdPPK1 mutant compared with the WT and were killed less rapidly, indicating a role of poly P and/or DdPPK1 in phagocytosis. On Pseudomonas aeruginosa lawns, cleared plaques were observed with the bacterial PPK1 mutant but not with the WT P. aeruginosa. Thus, poly P is important in predation both for the predator and prey.
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Affiliation(s)
- Haiyu Zhang
- Department of Biochemistry, Stanford University School of Medicine, Stanford, CA 94305-5307, USA
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Escalante R, Moreno N, Sastre L. Dictyostelium discoideum developmentally regulated genes whose expression is dependent on MADS box transcription factor SrfA. Eukaryot Cell 2004; 2:1327-35. [PMID: 14665466 PMCID: PMC326651 DOI: 10.1128/ec.2.6.1327-1335.2003] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The MADS box transcription factor SrfA is required for spore differentiation in Dictyostelium discoideum. srfA null strains form rounded spores that do not resist adverse environmental conditions. Five genes whose expression is dependent on SrfA have been isolated by differential hybridization. One of these genes, sigC, is identical to phg1b, previously characterized in mutants with altered adhesive properties and found to encode a nine-transmembrane-domain protein. This gene is transcribed into two mRNAs as the result of alternative splicing of two internal exons. The slower-migrating mRNA codes for a shorter protein that lacks the first transmembrane fragment and is not expressed in srfA null strains. The other four genes (sigA, sigB, sigD, and 45D) are expressed only during late developmental stages. In situ hybridization experiments showed that expression of sigA, sigB, and sigD is restricted to the sorus of developing structures. sigA codes for a homologue of malate dehydrogenase that converts pyruvate to malate to replenish the tricarboxylic acid cycle. sigB encodes a protein with significant similarity to the GP63 metalloproteinase of Leishmania, leishmanolysin. The sequence of SigD is highly similar to that of several spore coat proteins of D. discoideum, and it may play a role in that structure. The gene 45D codes for an RNA-binding protein homologue whose expression is also dependent on the GATA transcription factor stalky (StkA). The expression of sigB is also dependent on both SrfA and StkA. The expression of 45D, but not of sigA, sigB, sigC, and sigD, can be induced in srfA null cells by constitutive protein kinase A activation. Strains in which either sigA, sigB, or sigD is disrupted were isolated and found to form spores that are not detectably different from those of wild-type strains.
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Affiliation(s)
- Ricardo Escalante
- Instituto de Investigaciones Biomédicas, CSIC/UAM, 28029 Madrid, Spain
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