An expanded and largely complete upper Paleocene to upper Eocene section was recovered from the p... more An expanded and largely complete upper Paleocene to upper Eocene section was recovered from the pelagic cap overlying Allison Guyot, Mid-Pacific Mountains at Ocean Drilling Program (ODP) Site 865 (18°26'N, 179°33'W; paleodepth 1300-1500 m). Reconstructions show that the site was within a few degrees of the equator during the Paleogene. Because no other Paleogene sections have been recovered in the Pacific Ocean at such a low latitude, Site 865 provides a unique record of equatorial Pacific paleoceanography. Detailed stable isotopic investigations were conducted on three planktonic foraminiferal taxa (species of Acarinina, Morozovella, and Subbotina). We studied benthic foraminiferal isotopes at much lower resolution on species of Cibicidoides and Lenticulina, Nuttallides truempyi and Gavelinella beccariiformis, because of their exceptional rarity. The d18O and d13C stratigraphies from Site 865 are generally similar to those derived from other Paleocene and Eocene sections. The planktonic foraminiferal records at Site 865, however, include significantly less short-term, single-sample variability than those from higher-latitude sites, indicating that this tropical, oligotrophic location had a comparatively stable water column structure with a deep mixed layer and less seasonal variability. Low-amplitude (0.1-0.8 per mil) oscillations on timescales of 250,000 to 300,000 years correlate between the d13C records of all planktonic taxa and may represent fluctuations in the mixing intensity of surface waters. Peak sea surface temperatures of 24°-25°C occurred in the earliest Eocene, followed by a rapid cooling of 3-6°C in the late early Eocene. Temperatures remained cool and stable through the middle Eocene. In the late Eocene, surface water temperatures decreased further. Vertical temperature gradients decreased dramatically in the late Paleocene and were relatively constant through much of the Eocene but increased markedly in the late Eocene. Intermediate waters warmed through the late Paleocene, reaching a maximum te [...]
ABSTRACT Variability has been reported in the toxicity potential of Pfiesteria piscicida that is ... more ABSTRACT Variability has been reported in the toxicity potential of Pfiesteria piscicida that is partly a function of the history of exposure to live fish. Grazing properties of P. piscicida and its susceptibility to ciliate predation were compared in three functional types or toxicity states of this species: actively toxic cultures, cultures with temporary loss of demonstrable toxicity, and cultures with no demonstrable toxicity. Pronounced differences in predator–prey interactions were found between actively toxic cultures and cultures with reduced toxicity. When grown with Rhodomonas sp. (Cryptophyceae) prey, specific growth rates were relatively low in actively toxic cultures under both relatively high and low irradiances. In the cultures with reduced toxicity, prey chloroplast material was apparent in nearly 100% of dinoflagellate cells 3 h after feeding, while chloroplast inclusions were found in <40% of actively toxic cells for ≤16 h (high light) and ≤23 h (low light). These results suggest a relatively high reliance on phagotrophic carbon assimilation and more rapid response to algal prey availability in Pfiesteria cells with lower toxicity. Grazing by two euplotid benthic ciliates (Euplotes vannus and E. woodruffi) on P. piscicida also varied among functional types. Grazing on actively toxic P. piscicida cells did not occur, whereas net positive ingestion rates were calculated for the other prey cultures. These results support concurrent experimental findings that a natural assemblage of microzooplankton displayed lower grazing potential on actively toxic P. piscicida than on cultures with reduced toxicity. In summary, pronounced differences in trophic interactions were found between actively toxic cultures and those with reduced or undetectable toxicity, providing additional evidence of the importance of cellular toxicity in the trophic ecology of Pfiesteria.
... Production of alkaline phosphatases generally is repressed by high extracellular or intracell... more ... Production of alkaline phosphatases generally is repressed by high extracellular or intracellular phosphate concentrations, while most acid phosphatases are constitutively synthesized by cells ( [Kuenzler and Perras, 1965] , [Wynne, 1977] , [Cembella et al., 1984] and [Jansson ...
We describe the two species of the toxic Pfiesteria complex to date (Pfiesteria piscicida and Pfi... more We describe the two species of the toxic Pfiesteria complex to date (Pfiesteria piscicida and Pfiesteria shumwayae), their complex life cycles, and the characteristics required for inclusion within this complex. These species resemble P. piscicida Steidinger & Burkholder and also have a) strong attraction to fresh fish tissues and excreta, b) toxic activity stimulated by live fish, and c) production of toxin that can cause fish death and disease. Amoeboid stages were verified in 1992–1997 by our laboratory (various stages from toxic cultures) and that of K. Steidinger and co-workers (filose amoebae in nontoxic cultures), and in 2000 by H. Marshall and co-workers (various stages from toxic cultures), from clonal Pfiesteria spp. cultures, using species-specific polymerase chain reaction-based molecular probes with cross-confirmation by an independent specialist. Data were provided from tests of the hypothesis that Pfiesteria strains differ in response to fresh fish mucus and excreta, ...
Intensive stable isotopic investigations were conducted on the upper Paleocene to upper Eocene pe... more Intensive stable isotopic investigations were conducted on the upper Paleocene to upper Eocene pelagic cap sequence recovered at Site 865, Allison Guyot, Mid-Pacific Mountains. The sequence consists of calcareous ooze with an unusually high content of well-preserved planktonic foraminifers. Benthic foraminifers, although exceptionally rare, are also nearly unaltered. Isotopic analyses were performed on three separate planktonic (species of Acarinina, Morozovella, and Subbotina) and four benthic taxa (species of Cibicidoides and Lenticulina, Gavelinella beccariiformis, and Nuttallides truempyi). We present results of detailed stable isotopic investigations (δ 18 θ and δ13C) of the uppermost Paleocene and lowermost Eocene intervals in two holes (865B and 865C) and of the entire upper Paleocene to upper Eocene in Hole 865B.
Keywords: Pfiesteria, meiosis, flow cytometry, dinoflagellate, heterotrophy, sexual reproduction,... more Keywords: Pfiesteria, meiosis, flow cytometry, dinoflagellate, heterotrophy, sexual reproduction, asexual reproduction. Thesis (Ph. D.)--North Carolina State University. Includes bibliographical references. Includes vita.
Lignin and complex polysaccharides limit the efficiency of chemical and enzymatic conversion of l... more Lignin and complex polysaccharides limit the efficiency of chemical and enzymatic conversion of lignocellulosic biomass into ethanol. Processing technologies that address these problems are needed to advance lignocellulosic biofuel production. In the current research, whole-organism wood decay fungi were utilized as a pretreatment process for improved lignocellulosic bioconversion. Corn stover, Miscanthus, switchgrass, kenaf, and tulip poplar were selectively decayed with white rot (Ceriporiopsis subvermispora) and/or brown rot (Postia placenta) fungal treatments. Both white-rot and brown-rot fungi were successfully grown alone or in succession on all biomass types tested. Significant lignin removal and minimal polysaccharide loss were observed in some treatments, resulting in biomass with significantly improved chemical and mechanical properties for downstream conversion into ethanol. Glucose analysis determined that select fungal pretreatments effectively depolymerized lignin and ...
Dinoflagellates are a group of unicellular protists that can be identified using the light micros... more Dinoflagellates are a group of unicellular protists that can be identified using the light microscope, and are (usually) recognized by their golden-brown plastids, assimilative cell with indented waist, distinctive swimming pattern, and relatively large nucleus that contains visible chromosomes. Shared characteristics of the group include: two dissimilar flagella in motile cells; an unusual genome consisting of liquid, crystal-like chromosomes; and a haplontic life cycle that often contains a non-motile, dormant cyst stage. Freshwater dinoflagellates are diverse and may be phototrophic, predatory, or both (mixotrophic). They can be found in most aquatic habitats throughout the seasons; although flagship taxa, such as Ceratium, Peridinium, and Gymnodinium, are typically found as phytoplankton in calm, lentic waters during warmer months. This chapter updates taxonomy (extensive splitting of the genera Peridinium, Peridiniopsis, and Woloszynskia), identification of genera via microscopy, and adds molecular information on taxa and group systematics where available.
International Biodeterioration & Biodegradation, 2015
ABSTRACT In order to examine the potential efficacy of simultaneous dual-species fungal treatment... more ABSTRACT In order to examine the potential efficacy of simultaneous dual-species fungal treatment of wood for lignocellulosic ethanol production, whole organism fungal biopulping methods utilizing white rot (Ceriporiopsis subvermispora) and brown rot (Postia placenta) fungi alone or in co-culture were compared for effect on wood microstructure, chemical composition, and enzymatic sugar solubilization. Liriodendron tulipifera wood chips exposed for 30 days to C. subvermispora and/or P. placenta fungi alone or in co-culture exhibited qualitative differences in wood microstructure, but did not significantly differ in final percent composition of holocellulose, α-cellulose, or lignin content compared to controls. All fungal treatments increased the soluble reducing sugar yield of enzymatic hydrolysis by ca. 28–30% over sterile controls. The co-culture fungal treatment did not significantly differ in reducing sugar yield compared to monoculture treatments, suggesting an unexpected lack of additive or other synergistic species effects on wood degradation using these fungi in co-culture. Paired interaction agar plate assays demonstrated that C. subvermispora and P. placenta exhibited mutual distance-mediated growth inhibition that was independent of substrate type or availability, suggesting an explanation for the observed lack of degradative synergy between these taxa. This study is the first to report the effects of simultaneous co-treatment with white and brown rot fungi, highlights the need for further optimization of methods to account for specialized fungal degradative mechanisms, and examines the potential influence of competitive interactions in whole-organism biopulping treatments utilizing different taxa.
An expanded and largely complete upper Paleocene to upper Eocene section was recovered from the p... more An expanded and largely complete upper Paleocene to upper Eocene section was recovered from the pelagic cap overlying Allison Guyot, Mid-Pacific Mountains at Ocean Drilling Program (ODP) Site 865 (18°26'N, 179°33'W; paleodepth 1300-1500 m). Reconstructions show that the site was within a few degrees of the equator during the Paleogene. Because no other Paleogene sections have been recovered in the Pacific Ocean at such a low latitude, Site 865 provides a unique record of equatorial Pacific paleoceanography. Detailed stable isotopic investigations were conducted on three planktonic foraminiferal taxa (species of Acarinina, Morozovella, and Subbotina). We studied benthic foraminiferal isotopes at much lower resolution on species of Cibicidoides and Lenticulina, Nuttallides truempyi and Gavelinella beccariiformis, because of their exceptional rarity. The d18O and d13C stratigraphies from Site 865 are generally similar to those derived from other Paleocene and Eocene sections. The planktonic foraminiferal records at Site 865, however, include significantly less short-term, single-sample variability than those from higher-latitude sites, indicating that this tropical, oligotrophic location had a comparatively stable water column structure with a deep mixed layer and less seasonal variability. Low-amplitude (0.1-0.8 per mil) oscillations on timescales of 250,000 to 300,000 years correlate between the d13C records of all planktonic taxa and may represent fluctuations in the mixing intensity of surface waters. Peak sea surface temperatures of 24°-25°C occurred in the earliest Eocene, followed by a rapid cooling of 3-6°C in the late early Eocene. Temperatures remained cool and stable through the middle Eocene. In the late Eocene, surface water temperatures decreased further. Vertical temperature gradients decreased dramatically in the late Paleocene and were relatively constant through much of the Eocene but increased markedly in the late Eocene. Intermediate waters warmed through the late Paleocene, reaching a maximum te [...]
ABSTRACT Variability has been reported in the toxicity potential of Pfiesteria piscicida that is ... more ABSTRACT Variability has been reported in the toxicity potential of Pfiesteria piscicida that is partly a function of the history of exposure to live fish. Grazing properties of P. piscicida and its susceptibility to ciliate predation were compared in three functional types or toxicity states of this species: actively toxic cultures, cultures with temporary loss of demonstrable toxicity, and cultures with no demonstrable toxicity. Pronounced differences in predator–prey interactions were found between actively toxic cultures and cultures with reduced toxicity. When grown with Rhodomonas sp. (Cryptophyceae) prey, specific growth rates were relatively low in actively toxic cultures under both relatively high and low irradiances. In the cultures with reduced toxicity, prey chloroplast material was apparent in nearly 100% of dinoflagellate cells 3 h after feeding, while chloroplast inclusions were found in <40% of actively toxic cells for ≤16 h (high light) and ≤23 h (low light). These results suggest a relatively high reliance on phagotrophic carbon assimilation and more rapid response to algal prey availability in Pfiesteria cells with lower toxicity. Grazing by two euplotid benthic ciliates (Euplotes vannus and E. woodruffi) on P. piscicida also varied among functional types. Grazing on actively toxic P. piscicida cells did not occur, whereas net positive ingestion rates were calculated for the other prey cultures. These results support concurrent experimental findings that a natural assemblage of microzooplankton displayed lower grazing potential on actively toxic P. piscicida than on cultures with reduced toxicity. In summary, pronounced differences in trophic interactions were found between actively toxic cultures and those with reduced or undetectable toxicity, providing additional evidence of the importance of cellular toxicity in the trophic ecology of Pfiesteria.
... Production of alkaline phosphatases generally is repressed by high extracellular or intracell... more ... Production of alkaline phosphatases generally is repressed by high extracellular or intracellular phosphate concentrations, while most acid phosphatases are constitutively synthesized by cells ( [Kuenzler and Perras, 1965] , [Wynne, 1977] , [Cembella et al., 1984] and [Jansson ...
We describe the two species of the toxic Pfiesteria complex to date (Pfiesteria piscicida and Pfi... more We describe the two species of the toxic Pfiesteria complex to date (Pfiesteria piscicida and Pfiesteria shumwayae), their complex life cycles, and the characteristics required for inclusion within this complex. These species resemble P. piscicida Steidinger & Burkholder and also have a) strong attraction to fresh fish tissues and excreta, b) toxic activity stimulated by live fish, and c) production of toxin that can cause fish death and disease. Amoeboid stages were verified in 1992–1997 by our laboratory (various stages from toxic cultures) and that of K. Steidinger and co-workers (filose amoebae in nontoxic cultures), and in 2000 by H. Marshall and co-workers (various stages from toxic cultures), from clonal Pfiesteria spp. cultures, using species-specific polymerase chain reaction-based molecular probes with cross-confirmation by an independent specialist. Data were provided from tests of the hypothesis that Pfiesteria strains differ in response to fresh fish mucus and excreta, ...
Intensive stable isotopic investigations were conducted on the upper Paleocene to upper Eocene pe... more Intensive stable isotopic investigations were conducted on the upper Paleocene to upper Eocene pelagic cap sequence recovered at Site 865, Allison Guyot, Mid-Pacific Mountains. The sequence consists of calcareous ooze with an unusually high content of well-preserved planktonic foraminifers. Benthic foraminifers, although exceptionally rare, are also nearly unaltered. Isotopic analyses were performed on three separate planktonic (species of Acarinina, Morozovella, and Subbotina) and four benthic taxa (species of Cibicidoides and Lenticulina, Gavelinella beccariiformis, and Nuttallides truempyi). We present results of detailed stable isotopic investigations (δ 18 θ and δ13C) of the uppermost Paleocene and lowermost Eocene intervals in two holes (865B and 865C) and of the entire upper Paleocene to upper Eocene in Hole 865B.
Keywords: Pfiesteria, meiosis, flow cytometry, dinoflagellate, heterotrophy, sexual reproduction,... more Keywords: Pfiesteria, meiosis, flow cytometry, dinoflagellate, heterotrophy, sexual reproduction, asexual reproduction. Thesis (Ph. D.)--North Carolina State University. Includes bibliographical references. Includes vita.
Lignin and complex polysaccharides limit the efficiency of chemical and enzymatic conversion of l... more Lignin and complex polysaccharides limit the efficiency of chemical and enzymatic conversion of lignocellulosic biomass into ethanol. Processing technologies that address these problems are needed to advance lignocellulosic biofuel production. In the current research, whole-organism wood decay fungi were utilized as a pretreatment process for improved lignocellulosic bioconversion. Corn stover, Miscanthus, switchgrass, kenaf, and tulip poplar were selectively decayed with white rot (Ceriporiopsis subvermispora) and/or brown rot (Postia placenta) fungal treatments. Both white-rot and brown-rot fungi were successfully grown alone or in succession on all biomass types tested. Significant lignin removal and minimal polysaccharide loss were observed in some treatments, resulting in biomass with significantly improved chemical and mechanical properties for downstream conversion into ethanol. Glucose analysis determined that select fungal pretreatments effectively depolymerized lignin and ...
Dinoflagellates are a group of unicellular protists that can be identified using the light micros... more Dinoflagellates are a group of unicellular protists that can be identified using the light microscope, and are (usually) recognized by their golden-brown plastids, assimilative cell with indented waist, distinctive swimming pattern, and relatively large nucleus that contains visible chromosomes. Shared characteristics of the group include: two dissimilar flagella in motile cells; an unusual genome consisting of liquid, crystal-like chromosomes; and a haplontic life cycle that often contains a non-motile, dormant cyst stage. Freshwater dinoflagellates are diverse and may be phototrophic, predatory, or both (mixotrophic). They can be found in most aquatic habitats throughout the seasons; although flagship taxa, such as Ceratium, Peridinium, and Gymnodinium, are typically found as phytoplankton in calm, lentic waters during warmer months. This chapter updates taxonomy (extensive splitting of the genera Peridinium, Peridiniopsis, and Woloszynskia), identification of genera via microscopy, and adds molecular information on taxa and group systematics where available.
International Biodeterioration & Biodegradation, 2015
ABSTRACT In order to examine the potential efficacy of simultaneous dual-species fungal treatment... more ABSTRACT In order to examine the potential efficacy of simultaneous dual-species fungal treatment of wood for lignocellulosic ethanol production, whole organism fungal biopulping methods utilizing white rot (Ceriporiopsis subvermispora) and brown rot (Postia placenta) fungi alone or in co-culture were compared for effect on wood microstructure, chemical composition, and enzymatic sugar solubilization. Liriodendron tulipifera wood chips exposed for 30 days to C. subvermispora and/or P. placenta fungi alone or in co-culture exhibited qualitative differences in wood microstructure, but did not significantly differ in final percent composition of holocellulose, α-cellulose, or lignin content compared to controls. All fungal treatments increased the soluble reducing sugar yield of enzymatic hydrolysis by ca. 28–30% over sterile controls. The co-culture fungal treatment did not significantly differ in reducing sugar yield compared to monoculture treatments, suggesting an unexpected lack of additive or other synergistic species effects on wood degradation using these fungi in co-culture. Paired interaction agar plate assays demonstrated that C. subvermispora and P. placenta exhibited mutual distance-mediated growth inhibition that was independent of substrate type or availability, suggesting an explanation for the observed lack of degradative synergy between these taxa. This study is the first to report the effects of simultaneous co-treatment with white and brown rot fungi, highlights the need for further optimization of methods to account for specialized fungal degradative mechanisms, and examines the potential influence of competitive interactions in whole-organism biopulping treatments utilizing different taxa.
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