The Experts below are selected from a list of 6861 Experts worldwide ranked by ideXlab platform
Maiko Kagami - One of the best experts on this subject based on the ideXlab platform.
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intercomparison of two fluorescent dyes to visualize Parasitic Fungi chytridiomycota on phytoplankton
Microbial Ecology, 2021Co-Authors: Isabell Klawonn, Maiko Kagami, Hanspeter Grossart, Susanne Dunker, Silke Van Den WyngaertAbstract:Fungal microparasites (here chytrids) are widely distributed and yet, they are often overlooked in aquatic environments. To facilitate the detection of microparasites, we revisited the applicability of two fungal cell wall markers, Calcofluor White (CFW) and wheat germ agglutinin (WGA), for the direct visualization of chytrid infections on phytoplankton in laboratory-maintained isolates and field-sampled communities. Using a comprehensive set of chytrid-phytoplankton model pathosystems, we verified the staining pattern on diverse morphological structures of chytrids via fluorescence microscopy. Empty sporangia were stained most effectively, followed by encysted zoospores and im-/mature sporangia, while the staining success was more variable for rhizoids, stalks, and resting spores. In a few instances, the staining was unsuccessful (mostly with WGA), presumably due to insufficient cell fixation, gelatinous cell coatings, and multilayered cell walls. CFW and WGA staining could be done in Utermohl chambers or on polycarbonate filters, but CFW staining on filters seemed less advisable due to high background fluorescence. To visualize chytrids, 1 µg dye mL-1 was sufficient (but 5 µg mL-1 are recommended). Using a dual CFW-WGA staining protocol, we detected multiple, mostly undescribed chytrids in two natural systems (freshwater and coastal), while falsely positive or negative stained cells were well detectable. As a proof-of-concept, we moreover conducted imaging flow cytometry, as a potential high-throughput technology for quantifying chytrid infections. Our guidelines and recommendations are expected to facilitate the detection of chytrid epidemics and to unveil their ecological and economical imprint in natural and engineered aquatic systems.
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temporal variation in community structure of zoosporic Fungi in lake biwa japan
Aquatic Microbial Ecology, 2021Co-Authors: Peixue Song, Maiko Kagami, Shoko Tanabe, Naoshige Goto, Kensuke Seto, Syuhei BanAbstract:Zoosporic Fungi play an important role in aquatic environments, but their diversity, especially that of Parasitic Fungi of phytoplankton, has still not been fully revealed. We conducted monthly analyses of the community structure of zoosporic Fungi at a pelagic site in Lake Biwa, Japan, from May to December 2016. Metabarcoding analysis, targeted to a large subunit region of ribosomal DNA in the nano-size fraction of particles (2-20 µm), was carried out on the samples. We also counted large phytoplankton and chytrid sporangia attached to the hosts. We detected 3 zoosporic fungal phyla (Blastocladiomycota, Chytridiomycota and Cryptomycota) within 107 operational taxonomic units (OTUs), in which Chytridiomycota was the most diverse and abundant phylum. Few fungal OTUs overlapped between months, and specific communities were detected in each month. These results showed that diverse zoosporic Fungi with high temporal variability inhabited the lake. Five large phytoplankton species were found to be infected by chytrids: Staurastrum dorsidentiferum, S. rotula, Closterium aciculare, Asterionella formosa and Aulacoseira granulata. Some chytrids were detected by metabarcoding analysis: Zygophlyctis asterionellae infecting A. formosa, Staurastromyces oculus infecting S. dorsidentiferum and Pendulichytrium sphaericum infecting A. granulata. One OTU detected in association with infected C. aciculare by microscopic counting might have been an obligate Parasitic chytrid of C. aciculare. The results indicated that a combination of metabarcoding and microscopic analysis revealed more information on zoosporic Fungi, including those that are Parasitic.
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roles of Parasitic Fungi in aquatic food webs a theoretical approach
Freshwater Biology, 2011Co-Authors: Takeshi Miki, Gaku Takimoto, Maiko KagamiAbstract:Summary 1. Parasites are ubiquitous in ecosystems, but their roles in material transfer are poorly understood. Fungal parasites in freshwater ecosystems are of major importance to small heterotrophic eukaryotes and consume large phytoplankton that are resistant to zooplankton grazing. 2. To evaluate their ecosystem-level effects, we developed a simple food web model that incorporates competition between small and large phytoplankton for nutrients, zooplankton grazing on small phytoplankton, fungal parasitism on large phytoplankton and includes a newly discovered trophic link from fungal zoospores to zooplankton (F-Z link). 3. Our model demonstrates the likely occurrence of an indirect mutualism between Fungi and zooplankton, in which fungal parasitism increases zooplankton production by reducing the biomass of inedible large phytoplankton. Contradicting the expectation from a previous short-term experiment that the F-Z link may benefit zooplankton, the presence of the F-Z link can reduce material transfer from phytoplankton to zooplankton because of the negative effect of the indirect mutualism. The model indicates that high growth efficiency of Fungi on host tissue and their high nutrient status for zooplankton are crucial for the F-Z link to increase zooplankton production. 4. The model also indicates that the contribution of material transfer via F-Z link to zooplankton increases with nutrient availability. Our results suggest that Parasitic Fungi may be a key player in material transfer, especially in eutrophic ecosystems.
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Parasitic chytrids: their effects on phytoplankton communities and food-web dynamics
Hydrobiologia, 2007Co-Authors: Maiko Kagami, Bastiaan Willem Ibelings, Arnout De Bruin, Ellen DonkAbstract:Many phytoplankton species are susceptible to fungal parasitism. Parasitic Fungi of phytoplankton mainly belong to the Chytridiomycetes (chytrids). Here, we discuss the progression made in the study of chytrids that parasitize phytoplankton species. Specific fluorescent stains aid in the identification of chytrids in the field. The established culturing methods and the advances in molecular science offer good potential to gain a better insight into the mechanisms of epidemic development of chytrids and coevolution between chytrids and their algal hosts. Chytrids are often considered to be highly host-specific parasites, but the extent of host specificity has not been fully investigated. Chytrids may prefer larger host cells, since they would gain more resources, but whether hosts are really selected on the basis of size is not clear. The dynamics of chytrids epidemics in a number of studies were partly explained by environmental factors such as light, temperature, nutrients, pH, turbulence and zooplankton grazing. No generalization was made about the epidemic conditions; some state unfavorable conditions for the host growth support epidemic development, while others report epidemics even under optimal growth conditions for the host. Phytoplankton is not defenseless, and several mechanisms have been suggested, such as a hypersensitivity response, chemical defense, maintaining a high genetic diversity and multitrophic indirect defenses. Chytrids may also play an important role in food webs, because zoospores of chytrids have been found to be a good food source for zooplankton.
Télesphore Sime-ngando - One of the best experts on this subject based on the ideXlab platform.
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Parasitic Fungi of phytoplankton: Ecological roles and implications for microbial food webs
Aquatic Microbial Ecology, 2010Co-Authors: Serena Rasconi, Marlène Jobard, Télesphore Sime-ngandoAbstract:Microbial parasites typically are characterized by their small size, short generation time, and high rates of reproduction, with a simple life cycle occurring generally within a single host. They are diverse and ubiquitous in aquatic ecosystems, comprising viruses, prokaryotes and eukaryotes. Recently, environmental 18S-rDNA surveys of microbial eukaryotes have unveiled major infecting agents in pelagic systems, consisting primarily of chytrids (Chytridiomycota). Chytrids are external eucarpic parasites that infect diverse prokaryotic and eukaryotic algae, primarily diatoms and filamentous species. They produce specialized rhizoidal system within host cells, i.e. the nutrient conveying system for the formation of fruit bodies (sporangia) from which propagules (motile uniflagellated zoospores) are released in the environment. In this review, we summarize the ecological potentials of phytoplankton parasites, and infer the implications for food web dynamics. We focus on chytrids, together with other Parasitic eukaryotes, with special emphasis on (i) the role of microparasites in driving the structure of phytoplankton communities, (ii) the role of chytrid zoospores in matter and energy transfer, and (iii) the potential consequences of infections for food web dynamics. We raise the question of genetic potentials from host-parasite interactions, and also of how environmental factors might affect the host-parasite relationships in the pelagic realm.
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Unveiling fungal zooflagellates as members of freshwater picoeukaryotes: evidence from a molecular diversity study in a deep meromictic lake
Environmental Microbiology, 2007Co-Authors: Emilie Lefèvre, Corinne Bardot, Christophe Noël, Jean-françois Carrias, Eric Viscogliosi, Christian Amblard, Télesphore Sime-ngandoAbstract:This study presents an original 18S rRNA PCR survey of the freshwater picoeukaryote community, and was designed to detect unidentified heterotrophic picoflagellates (size range 0.6-5 microm) which are prevalent throughout the year within the heterotrophic flagellate assemblage in Lake Pavin. Four clone libraries were constructed from samples collected in two contrasting zones in the lake. Computerized statistic tools have suggested that sequence retrieval was representative of the in situ picoplankton diversity. The two sampling zones exhibited similar diversity patterns but shared only about 5% of the operational taxonomic units (OTUs). Phylogenetic analysis clustered our sequences into three taxonomic groups: Alveolates (30% of OTUs), Fungi (23%) and Cercozoa (19%). Fungi thus substantially contributed to the detected diversity, as was additionally supported by direct microscopic observations of fungal zoospores and sporangia. A large fraction of the sequences belonged to parasites, including Alveolate sequences affiliated to the genus Perkinsus known as zooparasites, and chytrids that include host-specific Parasitic Fungi of various freshwater phytoplankton species, primarily diatoms. Phylogenetic analysis revealed five novel clades that probably include typical freshwater environmental sequences. Overall, from the unsuspected fungal diversity unveiled, we think that fungal zooflagellates have been misidentified as phagotrophic nanoflagellates in previous studies. This is in agreement with a recent experimental demonstration that zoospore-producing Fungi and Parasitic activity may play an important role in aquatic food webs.
Xinyuan Shi - One of the best experts on this subject based on the ideXlab platform.
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Illumina MiSeq sequencing investigation of Chanhua (Cordyceps cicadae Shing) fungal community structures in different regions
Journal of Traditional Chinese Medical Sciences, 2018Co-Authors: Tengfei Liu, Hongmei Zhang, Xiaosa Shi, Yancong Zhang, Ziyao Liu, Ying Huang, Xinyuan ShiAbstract:Abstract Objective This study was carried out to elucidate the fungal diversity of Chanhua (Cordyceps cicadae Shing), which is an entomogenous fungal parasite that grows on wingless cicada nymphs. Methods Samples were collected from 10 different geographical regions including Yibing in Sichuan Province, Jiangsu Province, Jiangxi Province, Anhui Province, Guangdong Province, and Guangxi Autonomous Region. The Illumina MiSeq-based method was used to investigate the Chanhua fungal community structures. Results The results showed high fungal diversity, with 22 families found in the different samples, Eurotiomycetes was the dominant fungal family associated with Chanhua (composing 36.69% of the sample from Sichuan Mianyang), whereas Cordycipitaceae only composed 0.51% (Sichuan Yibing) to 0.33% (Guangdong) of these samples. Surprisingly, the proportion of Capnodiales was 5.27% in Sichuan Mianyang, whereas the percentage in other regions ranged from 4.35% (Sichuan Yibing) to 2.55% (Zhejiang), and the remaining proportion (more than 80%) was made up of unidentified fungus. Conclusions These findings contribute to a better understanding of Chanhua from different regions and revealed an unexpectedly and high amount of unidentified diversity of these fungal communities. These results indicate that Chanhua Parasitic Fungi need to be further analyzed and identified for finding new medical Fungi resources.
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Illumina MiSeq sequencing investigation of Chanhua (Cordyceps cicadae Shing) fungal community structures in different regions
Elsevier, 2018Co-Authors: Tengfei Liu, Hongmei Zhang, Xiaosa Shi, Yancong Zhang, Ziyao Liu, Ying Huang, Xinyuan ShiAbstract:Objective: This study was carried out to elucidate the fungal diversity of Chanhua (Cordyceps cicadae Shing), which is an entomogenous fungal parasite that grows on wingless cicada nymphs. Methods: Samples were collected from 10 different geographical regions including Yibing in Sichuan Province, Jiangsu Province, Jiangxi Province, Anhui Province, Guangdong Province, and Guangxi Autonomous Region. The Illumina MiSeq-based method was used to investigate the Chanhua fungal community structures. Results: The results showed high fungal diversity, with 22 families found in the different samples, Eurotiomycetes was the dominant fungal family associated with Chanhua (composing 36.69% of the sample from Sichuan Mianyang), whereas Cordycipitaceae only composed 0.51% (Sichuan Yibing) to 0.33% (Guangdong) of these samples. Surprisingly, the proportion of Capnodiales was 5.27% in Sichuan Mianyang, whereas the percentage in other regions ranged from 4.35% (Sichuan Yibing) to 2.55% (Zhejiang), and the remaining proportion (more than 80%) was made up of unidentified fungus. Conclusions: These findings contribute to a better understanding of Chanhua from different regions and revealed an unexpectedly and high amount of unidentified diversity of these fungal communities. These results indicate that Chanhua Parasitic Fungi need to be further analyzed and identified for finding new medical Fungi resources. Keywords: Different habitats, Fungal diversity, Chanhu
Tengfei Liu - One of the best experts on this subject based on the ideXlab platform.
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Illumina MiSeq sequencing investigation of Chanhua (Cordyceps cicadae Shing) fungal community structures in different regions
Journal of Traditional Chinese Medical Sciences, 2018Co-Authors: Tengfei Liu, Hongmei Zhang, Xiaosa Shi, Yancong Zhang, Ziyao Liu, Ying Huang, Xinyuan ShiAbstract:Abstract Objective This study was carried out to elucidate the fungal diversity of Chanhua (Cordyceps cicadae Shing), which is an entomogenous fungal parasite that grows on wingless cicada nymphs. Methods Samples were collected from 10 different geographical regions including Yibing in Sichuan Province, Jiangsu Province, Jiangxi Province, Anhui Province, Guangdong Province, and Guangxi Autonomous Region. The Illumina MiSeq-based method was used to investigate the Chanhua fungal community structures. Results The results showed high fungal diversity, with 22 families found in the different samples, Eurotiomycetes was the dominant fungal family associated with Chanhua (composing 36.69% of the sample from Sichuan Mianyang), whereas Cordycipitaceae only composed 0.51% (Sichuan Yibing) to 0.33% (Guangdong) of these samples. Surprisingly, the proportion of Capnodiales was 5.27% in Sichuan Mianyang, whereas the percentage in other regions ranged from 4.35% (Sichuan Yibing) to 2.55% (Zhejiang), and the remaining proportion (more than 80%) was made up of unidentified fungus. Conclusions These findings contribute to a better understanding of Chanhua from different regions and revealed an unexpectedly and high amount of unidentified diversity of these fungal communities. These results indicate that Chanhua Parasitic Fungi need to be further analyzed and identified for finding new medical Fungi resources.
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Illumina MiSeq sequencing investigation of Chanhua (Cordyceps cicadae Shing) fungal community structures in different regions
Elsevier, 2018Co-Authors: Tengfei Liu, Hongmei Zhang, Xiaosa Shi, Yancong Zhang, Ziyao Liu, Ying Huang, Xinyuan ShiAbstract:Objective: This study was carried out to elucidate the fungal diversity of Chanhua (Cordyceps cicadae Shing), which is an entomogenous fungal parasite that grows on wingless cicada nymphs. Methods: Samples were collected from 10 different geographical regions including Yibing in Sichuan Province, Jiangsu Province, Jiangxi Province, Anhui Province, Guangdong Province, and Guangxi Autonomous Region. The Illumina MiSeq-based method was used to investigate the Chanhua fungal community structures. Results: The results showed high fungal diversity, with 22 families found in the different samples, Eurotiomycetes was the dominant fungal family associated with Chanhua (composing 36.69% of the sample from Sichuan Mianyang), whereas Cordycipitaceae only composed 0.51% (Sichuan Yibing) to 0.33% (Guangdong) of these samples. Surprisingly, the proportion of Capnodiales was 5.27% in Sichuan Mianyang, whereas the percentage in other regions ranged from 4.35% (Sichuan Yibing) to 2.55% (Zhejiang), and the remaining proportion (more than 80%) was made up of unidentified fungus. Conclusions: These findings contribute to a better understanding of Chanhua from different regions and revealed an unexpectedly and high amount of unidentified diversity of these fungal communities. These results indicate that Chanhua Parasitic Fungi need to be further analyzed and identified for finding new medical Fungi resources. Keywords: Different habitats, Fungal diversity, Chanhu
Ellen Donk - One of the best experts on this subject based on the ideXlab platform.
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Parasitic chytrids: their effects on phytoplankton communities and food-web dynamics
Hydrobiologia, 2007Co-Authors: Maiko Kagami, Bastiaan Willem Ibelings, Arnout De Bruin, Ellen DonkAbstract:Many phytoplankton species are susceptible to fungal parasitism. Parasitic Fungi of phytoplankton mainly belong to the Chytridiomycetes (chytrids). Here, we discuss the progression made in the study of chytrids that parasitize phytoplankton species. Specific fluorescent stains aid in the identification of chytrids in the field. The established culturing methods and the advances in molecular science offer good potential to gain a better insight into the mechanisms of epidemic development of chytrids and coevolution between chytrids and their algal hosts. Chytrids are often considered to be highly host-specific parasites, but the extent of host specificity has not been fully investigated. Chytrids may prefer larger host cells, since they would gain more resources, but whether hosts are really selected on the basis of size is not clear. The dynamics of chytrids epidemics in a number of studies were partly explained by environmental factors such as light, temperature, nutrients, pH, turbulence and zooplankton grazing. No generalization was made about the epidemic conditions; some state unfavorable conditions for the host growth support epidemic development, while others report epidemics even under optimal growth conditions for the host. Phytoplankton is not defenseless, and several mechanisms have been suggested, such as a hypersensitivity response, chemical defense, maintaining a high genetic diversity and multitrophic indirect defenses. Chytrids may also play an important role in food webs, because zoospores of chytrids have been found to be a good food source for zooplankton.
