The Experts below are selected from a list of 318 Experts worldwide ranked by ideXlab platform
Chad A Rappleye - One of the best experts on this subject based on the ideXlab platform.
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eng1 and exg8 are the major β glucanases secreted by the fungal pathogen histoplasma capsulatum
Journal of Biological Chemistry, 2017Co-Authors: Andrew L Garfoot, Kacey L Dearing, Andrew D Vanschoiack, Vicki H Wysocki, Chad A RappleyeAbstract:Abstract Fungal cell walls contain β-glucan polysaccharides which stimulate immune responses when recognized by host immune cells. The fungal pathogen Histoplasma capsulatum minimizes detection of β-glucan by host cells through at least two mechanisms: concealment of β-Glucans beneath α-Glucans and enzymatic removal of any exposed β-glucan polysaccharides by the secreted glucanase Eng1. Histoplasma yeasts also secrete the putative glucanase Exg8, which may serve a similar role as Eng1 in removing exposed β-Glucans from the yeast cell surface. Here, we characterize the enzymatic specificity of the Eng1 and Exg8 proteins and show that Exg8 is an exo-β1,3-Glucanse and Eng1 is an endo-β1,3-glucanase. Together, Eng1 and Exg8 account for nearly all of the total secreted glucanase activity of Histoplasma yeasts. Both Eng1 and Exg8 proteins are secreted through a conventional secretion signal and modified post-translationally by O-linked glycosylation. Both glucanases have near maximal activity at temperature and pH conditions experienced during infection of host cells, supporting roles in Histoplasma pathogenesis. Exg8 has a higher specific activity than Eng1 for β1,3-Glucans, yet despite this, Exg8 does not reduce detection of yeasts by the host β-glucan receptor Dectin-1. Exg8 is largely dispensable for virulence in vivo, in contrast to Eng1. These results show that Histoplasma yeasts secrete two β1,3-glucanases and that Eng1 endoglucanase activity is the predominant factor responsible for removal of exposed cell wall β-Glucans to minimize host detection of Histoplasma yeasts.
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eng1 and exg8 are the major β glucanases secreted by the fungal pathogen histoplasma capsulatum
Journal of Biological Chemistry, 2017Co-Authors: Andrew L Garfoot, Kacey L Dearing, Andrew D Vanschoiack, Vicki H Wysocki, Chad A RappleyeAbstract:Fungal cell walls contain β-glucan polysaccharides that stimulate immune responses when recognized by host immune cells. The fungal pathogen Histoplasma capsulatum minimizes detection of β-glucan by host cells through at least two mechanisms: concealment of β-Glucans beneath α-Glucans and enzymatic removal of any exposed β-glucan polysaccharides by the secreted glucanase Eng1. Histoplasma yeasts also secrete the putative glucanase Exg8, which may serve a similar role as Eng1 in removing exposed β-Glucans from the yeast cell surface. Here, we characterize the enzymatic specificity of the Eng1 and Exg8 proteins and show that Exg8 is an exo-β1,3-glucanase and Eng1 is an endo-β1,3-glucanase. Together, Eng1 and Exg8 account for nearly all of the total secreted glucanase activity of Histoplasma yeasts. Both Eng1 and Exg8 proteins are secreted through a conventional secretion signal and are modified post-translationally by O-linked glycosylation. Both glucanases have near maximal activity at temperature and pH conditions experienced during infection of host cells, supporting roles in Histoplasma pathogenesis. Exg8 has a higher specific activity than Eng1 for β1,3-Glucans; yet despite this, Exg8 does not reduce detection of yeasts by the host β-glucan receptor Dectin-1. Exg8 is largely dispensable for virulence in vivo, in contrast to Eng1. These results show that Histoplasma yeasts secrete two β1,3-glucanases and that Eng1 endoglucanase activity is the predominant factor responsible for removal of exposed cell wall β-Glucans to minimize host detection of Histoplasma yeasts.
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Histoplasma capsulatum α-(1,3)-glucan blocks innate immune recognition by the β-glucan receptor
Proceedings of the National Academy of Sciences of the United States of America, 2007Co-Authors: Chad A Rappleye, Linda Eissenberg, William E. GoldmanAbstract:Successful infection by fungal pathogens depends on subversion of host immune mechanisms that detect conserved cell wall components such as β-Glucans. A less common polysaccharide, α-(1,3)-glucan, is a cell wall constituent of most fungal respiratory pathogens and has been correlated with pathogenicity or linked directly to virulence. However, the precise mechanism by which α-(1,3)-glucan promotes fungal virulence is unknown. Here, we show that α-(1,3)-glucan is present in the outermost layer of the Histoplasma capsulatum yeast cell wall and contributes to pathogenesis by concealing immunostimulatory β-Glucans from detection by host phagocytic cells. Production of proinflammatory TNFα by phagocytes was suppressed either by the presence of the α-(1,3)-glucan layer on yeast cells or by RNA interference based depletion of the host β-glucan receptor dectin-1. Thus, we have functionally defined key molecular components influencing the initial host–pathogen interaction in histoplasmosis and have revealed an important mechanism by which H. capsulatum thwarts the host immune system. Furthermore, we propose that the degree of this evasion contributes to the difference in pathogenic potential between dimorphic fungal pathogens and opportunistic fungi.
David L Williams - One of the best experts on this subject based on the ideXlab platform.
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Recognition of fungal Glucans by pattern recognition receptors.
2003Co-Authors: David L Williams, R. Rice, Jurgen Herre, Janet A. Willment, Philip R. Taylor, P. R. Gordon, Gordon D BrownAbstract:Glucans are (1→3)-β-D linked polymers of glucose that are major constituents of fungal cells walls. Glucans are known to stimulate innate immunity and they are thought to be fungal pathogen associated molecular patterns. Several recent discoveries have dramatically increased our knowledge of the cellular and molecular biology of Glucans. Among the most significant advances has been the identification and characterization of glucan specific pattern recognition receptors. This review examines the recent data on the identity, cellular distribution and binding interactions of receptors that recognize fungal Glucans. Specific emphasis is placed on the role of Dectin-1 and scavenger receptors as glucan binding sites. The definitive identification and characterization of glucan specific receptors is an essential prerequisite for deciphering the cellular and molecular interactions of fungal Glucans with the innate immune system
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human monocyte scavenger receptors are pattern recognition receptors for 1 3 β d Glucans
Journal of Leukocyte Biology, 2002Co-Authors: Peter J Rice, John Kalbfleisch, David L Williams, Harry E Ensley, Grigorij Kogan, Jim Kelley, William I BrowderAbstract:Glucans are cell wall constituents of fungi and bacteria that bind to pattern recognition receptors and modulate innate immunity, in part, by macrophage activation. We used surface plas- mon resonance to examine the binding of Glucans, differing in fine structure and charge density, to scavenger receptors on membranes isolated from human monocyte U937 cells. Experiments were performed at 25°C using a biosensor surface with immobilized acetylated low density lipoprotein (AcLDL). Inhibition of the binding by polyinosinic acid, but not polycytidylic acid, confirmed the in- teraction of scavenger receptors. Competition studies showed that there are at least two AcLDL binding sites on human U937 cells. Glucan phos- phate interacts with all sites, and the CM-Glucans and laminarin interact with a subset of sites. Poly- mer charge has a dramatic effect on the affinity of Glucans with macrophage scavenger receptors. However, it is also clear that human monocyte scavenger receptors recognize the basic glucan structure independent of charge. J. Leukoc. Biol. 72: 140-146; 2002.
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the influence of glucan polymer structure and solution conformation on binding to 1 3 β d glucan receptors in a human monocyte like cell line
Glycobiology, 2000Co-Authors: Antje Mueller, John Raptis, Robert D Stout, William Browder, Peter J Rice, John Kalbfleisch, Harry E Ensley, David L WilliamsAbstract:: Glucans are (1-3)-beta-D-linked polymers of glucose that are produced as fungal cell wall constituents and are also released into the extracellular milieu. Glucans modulate immune function via macrophage participation. The first step in macrophage activation by (1-3)-beta-D-Glucans is thought to be the binding of the polymer to specific macrophage receptors. We examined the binding/uptake of a variety of water soluble (1-3)-beta-D-Glucans and control polymers with different physicochemical properties to investigate the relationship between polymer structure and receptor binding in the CR3- human promonocytic cell line, U937. We observed that the U937 receptors were specific for (1-->3)-beta-D-glucan binding, since mannan, dextran, or barley glucan did not bind. Scleroglucan exhibited the highest binding affinity with an IC(50)of 23 nM, three orders of magnitude greater than the other (1-->3)-beta-D-glucan polymers examined. The rank order competitive binding affinities for the glucan polymers were scleroglucan>>>schizophyllan > laminarin > glucan phosphate > glucan sulfate. Scleroglucan also exhibited a triple helical solution structure (nu = 1.82, beta = 0.8). There were two different binding/uptake sites on U937 cells. Glucan phosphate and schizophyllan interacted nonselectively with the two sites. Scleroglucan and glucan sulfate interacted preferentially with one site, while laminarin interacted preferentially with the other site. These data indicate that U937 cells have at least two non-CR3 receptor(s) which specifically interact with (1-->3)-beta-D-Glucans and that the triple helical solution conformation, molecular weight and charge of the glucan polymer may be important determinants in receptor ligand interaction.
Peter J Rice - One of the best experts on this subject based on the ideXlab platform.
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differential high affinity interaction of dectin 1 with natural or synthetic Glucans is dependent upon primary structure and is influenced by polymer chain length and side chain branching
Journal of Pharmacology and Experimental Therapeutics, 2008Co-Authors: Elizabeth L Adams, Peter J Rice, Harry E Ensley, Bridget M Graves, Gordon D Brown, Siamon Gordon, Mario A Monteiro, Erzsebet Pappszabo, Douglas W Lowman, Trevor D PowerAbstract:Glucans are structurally diverse fungal biopolymers that stimulate innate immunity and are fungal pathogen-associated molecular patterns. Dectin-1 is a C-type lectin-like pattern recognition receptor that binds Glucans and induces innate immune responses to fungal pathogens. We examined the effect of glucan structure on recognition and binding by murine recombinant Dectin-1 with a library of natural product and synthetic (1-->3)-beta/(1-->6)-beta-Glucans as well as nonglucan polymers. Dectin-1 is highly specific for Glucans with a pure (1-->3)-beta-linked backbone structure. Although Dectin-1 is highly specific for (1-->3)-beta-d-Glucans, it does not recognize all Glucans equally. Dectin-1 differentially interacted with (1-->3)-beta-d-Glucans over a very wide range of binding affinities (2.6 mM-2.2 pM). One of the most striking observations that emerged from this study was the remarkable high-affinity interaction of Dectin-1 with certain Glucans (2.2 pM). These data also demonstrated that synthetic glucan ligands interact with Dectin-1 and that binding affinity increased in synthetic Glucans containing a single glucose side-chain branch. We also observed differential recognition of Glucans derived from saprophytes and pathogens. We found that glucan derived from a saprophytic yeast was recognized with higher affinity than glucan derived from the pathogen Candida albicans. Structural analysis demonstrated that glucan backbone chain length and (1-->6)-beta side-chain branching strongly influenced Dectin-1 binding affinity. These data demonstrate: 1) the specificity of Dectin-1 for Glucans; 2) that Dectin-1 differentiates between glucan ligands based on structural determinants; and 3) that Dectin-1 can recognize and interact with both natural product and synthetic glucan ligands.
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oral delivery and gastrointestinal absorption of soluble Glucans stimulate increased resistance to infectious challenge
Journal of Pharmacology and Experimental Therapeutics, 2005Co-Authors: Peter J Rice, Elizabeth L Adams, Tammy Ozmentskelton, Andres J Gonzalez, Matthew P Goldman, Brent E Lockhart, Luke A Barker, Kevin F Breuel, Warren K Deponti, John KalbfleischAbstract:Glucans are immunomodulatory carbohydrates found in the cell walls of fungi and certain bacteria. We examined the pharmacokinetics of three water-soluble Glucans (glucan phosphate, laminarin, and scleroglucan) after oral administration of 1 mg/kg doses in rats. Maximum plasma concentrations for glucan phosphate occurred at 4 h. In contrast, laminarin and scleroglucan showed two plasma peaks between 0.5 and 12 h. At 24 h, 27 +/- 3% of the glucan phosphate and 20 +/- 7% of the laminarin remained in the serum. Scleroglucan was rapidly absorbed and eliminated. The liver did not significantly contribute to the clearance of plasma glucan. Biological effects were further studied in mice. Following oral administration of 1 mg, Glucans were bound and internalized by intestinal epithelial cells and gut-associated lymphoid tissue (GALT) cells. Internalization of glucan by intestinal epithelial cells was not Dectin-dependent. GALT expression of Dectin-1 and toll-like receptor (TLR) 2, but not TLR4, increased following oral administration of glucan. Oral glucan increased systemic levels of interleukin (IL)-12 (151 +/- 15%) in mice. Oral glucan administration also increased survival in mice challenged with Staphylococcus aureus or Candida albicans. These data demonstrate that orally administered water-soluble Glucans translocate from the gastrointestinal (GI) tract into the systemic circulation. The Glucans are bound by GI epithelial and GALT cells, and they modulate the expression of pattern recognition receptors in the GALT, increase IL-12 expression, and induce protection against infectious challenge.
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human monocyte scavenger receptors are pattern recognition receptors for 1 3 β d Glucans
Journal of Leukocyte Biology, 2002Co-Authors: Peter J Rice, John Kalbfleisch, David L Williams, Harry E Ensley, Grigorij Kogan, Jim Kelley, William I BrowderAbstract:Glucans are cell wall constituents of fungi and bacteria that bind to pattern recognition receptors and modulate innate immunity, in part, by macrophage activation. We used surface plas- mon resonance to examine the binding of Glucans, differing in fine structure and charge density, to scavenger receptors on membranes isolated from human monocyte U937 cells. Experiments were performed at 25°C using a biosensor surface with immobilized acetylated low density lipoprotein (AcLDL). Inhibition of the binding by polyinosinic acid, but not polycytidylic acid, confirmed the in- teraction of scavenger receptors. Competition studies showed that there are at least two AcLDL binding sites on human U937 cells. Glucan phos- phate interacts with all sites, and the CM-Glucans and laminarin interact with a subset of sites. Poly- mer charge has a dramatic effect on the affinity of Glucans with macrophage scavenger receptors. However, it is also clear that human monocyte scavenger receptors recognize the basic glucan structure independent of charge. J. Leukoc. Biol. 72: 140-146; 2002.
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the influence of glucan polymer structure and solution conformation on binding to 1 3 β d glucan receptors in a human monocyte like cell line
Glycobiology, 2000Co-Authors: Antje Mueller, John Raptis, Robert D Stout, William Browder, Peter J Rice, John Kalbfleisch, Harry E Ensley, David L WilliamsAbstract:: Glucans are (1-3)-beta-D-linked polymers of glucose that are produced as fungal cell wall constituents and are also released into the extracellular milieu. Glucans modulate immune function via macrophage participation. The first step in macrophage activation by (1-3)-beta-D-Glucans is thought to be the binding of the polymer to specific macrophage receptors. We examined the binding/uptake of a variety of water soluble (1-3)-beta-D-Glucans and control polymers with different physicochemical properties to investigate the relationship between polymer structure and receptor binding in the CR3- human promonocytic cell line, U937. We observed that the U937 receptors were specific for (1-->3)-beta-D-glucan binding, since mannan, dextran, or barley glucan did not bind. Scleroglucan exhibited the highest binding affinity with an IC(50)of 23 nM, three orders of magnitude greater than the other (1-->3)-beta-D-glucan polymers examined. The rank order competitive binding affinities for the glucan polymers were scleroglucan>>>schizophyllan > laminarin > glucan phosphate > glucan sulfate. Scleroglucan also exhibited a triple helical solution structure (nu = 1.82, beta = 0.8). There were two different binding/uptake sites on U937 cells. Glucan phosphate and schizophyllan interacted nonselectively with the two sites. Scleroglucan and glucan sulfate interacted preferentially with one site, while laminarin interacted preferentially with the other site. These data indicate that U937 cells have at least two non-CR3 receptor(s) which specifically interact with (1-->3)-beta-D-Glucans and that the triple helical solution conformation, molecular weight and charge of the glucan polymer may be important determinants in receptor ligand interaction.
Gordon D Brown - One of the best experts on this subject based on the ideXlab platform.
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β Glucans and dectin 1
Annals of the New York Academy of Sciences, 2008Co-Authors: Vicky S Tsoni, Gordon D BrownAbstract:beta-Glucans are naturally occurring carbohydrates that possess immune-modulating activities, but their mechanisms of action are largely unknown. Recent discoveries, however, including identification of beta-glucan receptors, such as dectin-1, have started to shed some light on the mechanisms underlying the properties of these carbohydrates. The characterization of dectin-1, in particular, has revealed some of the processes involved in beta-glucan sensing, intracellular signaling, and induction of cellular responses and has provided new insights into the role of beta-Glucans in immunity and disease. Here we review both beta-Glucans and their receptor, dectin-1.
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differential high affinity interaction of dectin 1 with natural or synthetic Glucans is dependent upon primary structure and is influenced by polymer chain length and side chain branching
Journal of Pharmacology and Experimental Therapeutics, 2008Co-Authors: Elizabeth L Adams, Peter J Rice, Harry E Ensley, Bridget M Graves, Gordon D Brown, Siamon Gordon, Mario A Monteiro, Erzsebet Pappszabo, Douglas W Lowman, Trevor D PowerAbstract:Glucans are structurally diverse fungal biopolymers that stimulate innate immunity and are fungal pathogen-associated molecular patterns. Dectin-1 is a C-type lectin-like pattern recognition receptor that binds Glucans and induces innate immune responses to fungal pathogens. We examined the effect of glucan structure on recognition and binding by murine recombinant Dectin-1 with a library of natural product and synthetic (1-->3)-beta/(1-->6)-beta-Glucans as well as nonglucan polymers. Dectin-1 is highly specific for Glucans with a pure (1-->3)-beta-linked backbone structure. Although Dectin-1 is highly specific for (1-->3)-beta-d-Glucans, it does not recognize all Glucans equally. Dectin-1 differentially interacted with (1-->3)-beta-d-Glucans over a very wide range of binding affinities (2.6 mM-2.2 pM). One of the most striking observations that emerged from this study was the remarkable high-affinity interaction of Dectin-1 with certain Glucans (2.2 pM). These data also demonstrated that synthetic glucan ligands interact with Dectin-1 and that binding affinity increased in synthetic Glucans containing a single glucose side-chain branch. We also observed differential recognition of Glucans derived from saprophytes and pathogens. We found that glucan derived from a saprophytic yeast was recognized with higher affinity than glucan derived from the pathogen Candida albicans. Structural analysis demonstrated that glucan backbone chain length and (1-->6)-beta side-chain branching strongly influenced Dectin-1 binding affinity. These data demonstrate: 1) the specificity of Dectin-1 for Glucans; 2) that Dectin-1 differentiates between glucan ligands based on structural determinants; and 3) that Dectin-1 can recognize and interact with both natural product and synthetic glucan ligands.
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β‐Glucans and Dectin‐1
Annals of the New York Academy of Sciences, 2008Co-Authors: S. Vicky Tsoni, Gordon D BrownAbstract:beta-Glucans are naturally occurring carbohydrates that possess immune-modulating activities, but their mechanisms of action are largely unknown. Recent discoveries, however, including identification of beta-glucan receptors, such as dectin-1, have started to shed some light on the mechanisms underlying the properties of these carbohydrates. The characterization of dectin-1, in particular, has revealed some of the processes involved in beta-glucan sensing, intracellular signaling, and induction of cellular responses and has provided new insights into the role of beta-Glucans in immunity and disease. Here we review both beta-Glucans and their receptor, dectin-1.
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Recognition of fungal Glucans by pattern recognition receptors.
2003Co-Authors: David L Williams, R. Rice, Jurgen Herre, Janet A. Willment, Philip R. Taylor, P. R. Gordon, Gordon D BrownAbstract:Glucans are (1→3)-β-D linked polymers of glucose that are major constituents of fungal cells walls. Glucans are known to stimulate innate immunity and they are thought to be fungal pathogen associated molecular patterns. Several recent discoveries have dramatically increased our knowledge of the cellular and molecular biology of Glucans. Among the most significant advances has been the identification and characterization of glucan specific pattern recognition receptors. This review examines the recent data on the identity, cellular distribution and binding interactions of receptors that recognize fungal Glucans. Specific emphasis is placed on the role of Dectin-1 and scavenger receptors as glucan binding sites. The definitive identification and characterization of glucan specific receptors is an essential prerequisite for deciphering the cellular and molecular interactions of fungal Glucans with the innate immune system
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immune recognition a new receptor for beta Glucans
Nature, 2001Co-Authors: Gordon D Brown, Siamon GordonAbstract:The carbohydrate polymers known as β-1,3-d-Glucans exert potent effects on the immune system — stimulating antitumour and antimicrobial activity, for example — by binding to receptors on macrophages and other white blood cells and activating them. Although β-Glucans are known to bind to receptors, such as complement receptor 3 (ref. 1), there is evidence that another β-glucan receptor is present on macrophages. Here we identify this unknown receptor as dectin-1 (ref. 2), a finding that provides new insights into the innate immune recognition of β-Glucans.
Andrew L Garfoot - One of the best experts on this subject based on the ideXlab platform.
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eng1 and exg8 are the major β glucanases secreted by the fungal pathogen histoplasma capsulatum
Journal of Biological Chemistry, 2017Co-Authors: Andrew L Garfoot, Kacey L Dearing, Andrew D Vanschoiack, Vicki H Wysocki, Chad A RappleyeAbstract:Abstract Fungal cell walls contain β-glucan polysaccharides which stimulate immune responses when recognized by host immune cells. The fungal pathogen Histoplasma capsulatum minimizes detection of β-glucan by host cells through at least two mechanisms: concealment of β-Glucans beneath α-Glucans and enzymatic removal of any exposed β-glucan polysaccharides by the secreted glucanase Eng1. Histoplasma yeasts also secrete the putative glucanase Exg8, which may serve a similar role as Eng1 in removing exposed β-Glucans from the yeast cell surface. Here, we characterize the enzymatic specificity of the Eng1 and Exg8 proteins and show that Exg8 is an exo-β1,3-Glucanse and Eng1 is an endo-β1,3-glucanase. Together, Eng1 and Exg8 account for nearly all of the total secreted glucanase activity of Histoplasma yeasts. Both Eng1 and Exg8 proteins are secreted through a conventional secretion signal and modified post-translationally by O-linked glycosylation. Both glucanases have near maximal activity at temperature and pH conditions experienced during infection of host cells, supporting roles in Histoplasma pathogenesis. Exg8 has a higher specific activity than Eng1 for β1,3-Glucans, yet despite this, Exg8 does not reduce detection of yeasts by the host β-glucan receptor Dectin-1. Exg8 is largely dispensable for virulence in vivo, in contrast to Eng1. These results show that Histoplasma yeasts secrete two β1,3-glucanases and that Eng1 endoglucanase activity is the predominant factor responsible for removal of exposed cell wall β-Glucans to minimize host detection of Histoplasma yeasts.
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eng1 and exg8 are the major β glucanases secreted by the fungal pathogen histoplasma capsulatum
Journal of Biological Chemistry, 2017Co-Authors: Andrew L Garfoot, Kacey L Dearing, Andrew D Vanschoiack, Vicki H Wysocki, Chad A RappleyeAbstract:Fungal cell walls contain β-glucan polysaccharides that stimulate immune responses when recognized by host immune cells. The fungal pathogen Histoplasma capsulatum minimizes detection of β-glucan by host cells through at least two mechanisms: concealment of β-Glucans beneath α-Glucans and enzymatic removal of any exposed β-glucan polysaccharides by the secreted glucanase Eng1. Histoplasma yeasts also secrete the putative glucanase Exg8, which may serve a similar role as Eng1 in removing exposed β-Glucans from the yeast cell surface. Here, we characterize the enzymatic specificity of the Eng1 and Exg8 proteins and show that Exg8 is an exo-β1,3-glucanase and Eng1 is an endo-β1,3-glucanase. Together, Eng1 and Exg8 account for nearly all of the total secreted glucanase activity of Histoplasma yeasts. Both Eng1 and Exg8 proteins are secreted through a conventional secretion signal and are modified post-translationally by O-linked glycosylation. Both glucanases have near maximal activity at temperature and pH conditions experienced during infection of host cells, supporting roles in Histoplasma pathogenesis. Exg8 has a higher specific activity than Eng1 for β1,3-Glucans; yet despite this, Exg8 does not reduce detection of yeasts by the host β-glucan receptor Dectin-1. Exg8 is largely dispensable for virulence in vivo, in contrast to Eng1. These results show that Histoplasma yeasts secrete two β1,3-glucanases and that Eng1 endoglucanase activity is the predominant factor responsible for removal of exposed cell wall β-Glucans to minimize host detection of Histoplasma yeasts.
