Chytrids and Algae: I. Host–substrate Range, and Morphological Variation of Species of Rhizophydium

Barr, D. J. S.; Hickman, C. J.

doi:10.1139/b67-042

Cited by 26 publications

(13 citation statements)

References 5 publications

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“…This method is useful not only to obtain fungal zoospores for experiments, but also to prevent the possible development of a resistant host strain (only zoospore suspensions are transferred to new host cultures, instead of using an infected host culture for inoculation of new host cultures, where the risk of transferring resistant hosts is increased). Culturing chytrids without host algae is also possible in artificial media (Barr & Hickman, 1967b) or on agar plates (Barr, 1987). Both methods with or without host algae, however, need special attention that bacteria should not outgrow the chytrids.…”

Section: Culturing Chytridsmentioning

confidence: 99%

Parasitic chytrids: their effects on phytoplankton communities and food-web dynamics

et al. 2007

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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

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Section: Culturing Chytridsmentioning

confidence: 99%

Parasitic chytrids: their effects on phytoplankton communities and food-web dynamics

et al. 2007

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“…are both favoured by temperatures >15°C at optimum pH of about 7.3 (Sen 1988). Laboratory cultures and the maintenance of host -parasite systems growing under controlled conditions (Bruning & Ringelberg 1987, Bruning 1991 have suggested that the optimum temperature for fungal growth is highly variable and can be speciesspecific, generally ranging from 3°C (Van Donk & Ringelberg 1983) to 30°C (Barr & Hickman 1967). In freshwater environments, chytrids, especially those that infect diatoms, have a high affinity for low water temperatures (Ibelings et al 2003).…”

Section: Factors That Influence the Development Of Fungal Epidemicsmentioning

confidence: 99%

Parasitic fungi of phytoplankton: ecological roles and implications for microbial food webs

Rasconi¹,

Jobard²,

Sime-Ngando³

2011

Aquat. Microb. Ecol.

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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 systems within host cells, i.e. the nutrient conveying system for the formation of fruit bodies (sporangia) from which propagules (motile uniflagellated zoospores) are released into the environment. In this review, we summarize the ecological potential of parasites of phytoplankton and infer the implications for food web dynamics. We focus on chytrids, together with other parasitic eukaryotes, with special emphasis on (1) the role of microparasites in driving the structure of phytoplankton communities, (2) the role of chytrid zoospores in matter and energy transfer, and (3) the potential consequences of infections for food web dynamics. We raise the question of genetic potential from host -parasite interactions and also of how environmental factors might affect the host -parasite relationships in the pelagic realm.

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“…Amoebophrya species are mainly known as marine endoparasites in red-tide dinoflagellate blooms (Coats et al, 1996), and were intensively studied in oceans where they display a worldwide distribution (Park et al, 2004). In freshwater ecosystems, saprotrophs and parasites also include zoosporic fungi and some of them are host-specific to various phytoplankton species (Barr & Hickman, 1967;Gutman et al, 2009;Rasconi et al, 2009). …”

Section: Hidden Putative Ecological Potentials From Hfmentioning

confidence: 99%

“…More recent studies have indicated that the natural phytoplankton hosts indeed include both diverse populations of eukaryotic phytoplankton (Rasconi et al, 2009), and colonial and filamentous cyanobacteria in productive waters as well (Rasconi et al, 2009). Parasitic zoosporic fungi are often host specific, highly infective and extremely virulent in phytoplankton (Canter & Lund, 1951;Barr & Hickman, 1967;Holfeld, 1998;Gutman et al, 2009). They are considered relevant for the evolution of their hosts but also for the population dynamics and successions of phytoplankton communities (Van Donk & Ringelberg, 1983;De Bruin, 2006), with a prevalence of infection than can exceed 20% within a given population (Rasconi et al, 2009).…”

Section: Hidden Putative Ecological Potentials From Hfmentioning

confidence: 99%

Hidden diversity among aquatic heterotrophic flagellates: ecological potentials of zoosporic fungi

2010

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International audienceSince the emergence of the ‘microbial loop' concept, heterotrophic flagellates have received particular attention as grazers in aquatic ecosystems. These microbes have historically been regarded incorrectly as a homogeneous group of bacterivorous protists in aquatic systems. More recently, environmental rDNA surveys of small heterotrophic flagellates in the pelagic zone of freshwater ecosystems have provided new insights. (i) The dominant phyla found by molecular studies differed significantly from those known from morphological studies with the light microscope, (ii) the retrieved phylotypes generally belong to well-established eukaryotic clades, but there is a very large diversity within these clades and (iii) a substantial part of the retrieved sequences cannot be assigned to bacterivorous but can be assigned instead to parasitic and saprophytic organisms, such as zoosporic true fungi (chytrids), fungus-like organisms (stramenopiles), or virulent alveolate parasites (Perkinsozoa and Amoebophrya sp.). All these microorganisms are able to produce small zoospores to assure dispersal in water during their life-cycles. Based on the existing literature on true fungi and fungus-like organisms, and on the more recently published eukaryotic rDNA environmental studies and morphological observations, we conclude that previously overlooked microbial diversity and related ecological potentials require intensive investigation (i) for an improved understanding of the roles of heterotrophic flagellates in pelagic ecosystems and (ii) to properly integrate the concept of ‘the microbial loop' into modern pelagic microbial ecology

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Chytrids and Algae: I. Host–substrate Range, and Morphological Variation of Species of Rhizophydium

Cited by 26 publications

References 5 publications

Parasitic chytrids: their effects on phytoplankton communities and food-web dynamics

Parasitic chytrids: their effects on phytoplankton communities and food-web dynamics

Parasitic fungi of phytoplankton: ecological roles and implications for microbial food webs

Hidden diversity among aquatic heterotrophic flagellates: ecological potentials of zoosporic fungi

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