Open Access. Powered by Scholars. Published by Universities.®

Environmental Microbiology and Microbial Ecology Commons™

Open Access. Powered by Scholars. Published by Universities.®

Discipline
Institution
Keyword
Publication Year
Publication
Publication Type
File Type

Articles 1081 - 1110 of 1330

Full-Text Articles in Environmental Microbiology and Microbial Ecology

Dissecting Biological “Dark Matter” With Single-Cell Genetic Analysis Of Rare And Uncultivated Tm7 Microbes From The Human Mouth, Yann Marcy, Cleber C. Ouverney, Elisabeth M. Bik, Tina Lösekann, Natalia Ivanova, Hector Garcia Martin, Ernest Szeto, Darren Platt, Philip Hugenholtz, David A. Relman, Stephen R. Quake Jul 2007

Dissecting Biological “Dark Matter” With Single-Cell Genetic Analysis Of Rare And Uncultivated Tm7 Microbes From The Human Mouth, Yann Marcy, Cleber C. Ouverney, Elisabeth M. Bik, Tina Lösekann, Natalia Ivanova, Hector Garcia Martin, Ernest Szeto, Darren Platt, Philip Hugenholtz, David A. Relman, Stephen R. Quake

Faculty Publications, Biological Sciences

We have developed a microfluidic device that allows the isolation and genome amplification of individual microbial cells, thereby enabling organism-level genomic analysis of complex microbial ecosystems without the need for culture. This device was used to perform a directed survey of the human subgingival crevice and to isolate bacteria having rod-like morphology. Several isolated microbes had a 16S rRNA sequence that placed them in candidate phylum TM7, which has no cultivated or sequenced members. Genome amplification from individual TM7 cells allowed us to sequence and assemble >1,000 genes, providing insight into the physiology of members of this phylum. This approach …

Go to article

Microbial Observatories: Kilauea Volcano Observatory For Carbon Monoxide-Oxidizing Bacteria, Gary M. King Jul 2007

Microbial Observatories: Kilauea Volcano Observatory For Carbon Monoxide-Oxidizing Bacteria, Gary M. King

University of Maine Office of Research Administration: Grant Reports

Volcanic activity regularly creates new landforms from deposits of tephra, ash and lava. These initially sterile, pristine deposits undergo a range of physical, chemical and biological transformations that lead in some cases to diverse, complex ecosystems such as Hawaiian rainforests. Recent activity by the Kilauea volcano has created unique opportunities to understand the timing and controls of complex ecosystem development, and to analyze the roles of microbes as pioneering colonists that contribute to plant development and succession. The newly established Kilauea Volcano Microbial Observatory will compare the diversity and activity of carbon monoxide-oxidizing bacteria colonizing two different deposits currently 45 …

Go to article

Mammalian Cell Cytotoxicity Analysis Of Soybean Rust Fungicides, Steven L. Daniel, G. L. Hartman, E. D. Wagner, M. J. Plewa Jul 2007

Mammalian Cell Cytotoxicity Analysis Of Soybean Rust Fungicides, Steven L. Daniel, G. L. Hartman, E. D. Wagner, M. J. Plewa

Steven L. Daniel

No abstract provided.

Go to article

Mammalian Cell Cytotoxicity Analysis Of Soybean Rust Fungicides, Steven Daniel, G. Hartman, E. Wagner, M. Plewa Jul 2007

Mammalian Cell Cytotoxicity Analysis Of Soybean Rust Fungicides, Steven Daniel, G. Hartman, E. Wagner, M. Plewa

Faculty Research & Creative Activity

No abstract provided.

Go to article

Mammalian Cell Cytotoxicity Analysis Of Soybean Rust Fungicides, Steven L. Daniel, G. L. Hartman, E. D. Wagner, M. J. Plewa Jul 2007

Mammalian Cell Cytotoxicity Analysis Of Soybean Rust Fungicides, Steven L. Daniel, G. L. Hartman, E. D. Wagner, M. J. Plewa

Faculty Research & Creative Activity

No abstract provided.

Go to article

Molecular Genetics And Genomic Analysis Of Scytonemin Biosynthesis In Nostoc Punctiforme Atcc 29133, Tanya Soule, Valerie Stout, Wesley Swingley, J C. Meeks, Ferran Garcia-Pichel May 2007

Molecular Genetics And Genomic Analysis Of Scytonemin Biosynthesis In Nostoc Punctiforme Atcc 29133, Tanya Soule, Valerie Stout, Wesley Swingley, J C. Meeks, Ferran Garcia-Pichel

Tanya Soule

The indole-alkaloid scytonemin is the most common and widespread sunscreen among cyanobacteria. Previous research has focused on its nature, distribution, ecology, physiology, and biochemistry, but its molecular genetics have not been explored. In this study, a scytonemin-deficient mutant of the cyanobacterium Nostoc punctiforme ATCC 29133 was obtained by random transposon insertion into open reading frame NpR1273. The absence of scytonemin under conditions of induction by UV irradiation was the single phenotypic difference detected in a comparative analysis of the wild type and the mutant. A cause-effect relationship between the phenotype and the mutation in NpR1273 was demonstrated by constructing a …

Go to article

Parasites Alter Community Structure, Chelsea L. Wood, James E. Byers, Kathryn L. Cottingham, Irit Altman May 2007

Parasites Alter Community Structure, Chelsea L. Wood, James E. Byers, Kathryn L. Cottingham, Irit Altman

Dartmouth Scholarship

Parasites often play an important role in modifying the physiology and behavior of their hosts and may, consequently, mediate the influence hosts have on other components of an ecological community. Along the northern Atlantic coast of North America, the dominant herbivorous snail Littorina littorea structures rocky intertidal communities through strong grazing pressure and is frequently parasitized by the digenean trematode Cryptocotyle lingua. We hypothesized that the effects of parasitism on host physiology would induce behavioral changes in L. littorea, which in turn would modulate L. littorea's influence on intertidal community composition. Specifically, we hypothesized that C. lingua …

Go to article

Apres Le Deluge: Microbial Landscape Of New Orleans After The Hurricanes, Fred C. Dobbs May 2007

Apres Le Deluge: Microbial Landscape Of New Orleans After The Hurricanes, Fred C. Dobbs

OES Faculty Publications

No abstract provided.

Go to article

Biogeography And Genetic Diversity Of Toxin Producing Cyanobacteria In A Laurentian Great Lake, Johanna Maaria Rinta-Kanto May 2007

Biogeography And Genetic Diversity Of Toxin Producing Cyanobacteria In A Laurentian Great Lake, Johanna Maaria Rinta-Kanto

Doctoral Dissertations

The North American Great Lakes are a vital source on a global scale, as they hold ~18 % of the potable water resources on our planet. Cyanobacteria of the genus Microcystis are commonly found in fresh water environments around the world, and since the mid-1990s also in Lake Erie. The reasons for the success for these potentially toxic cyanobacteria in Lake Erie are not completely understood. In this study we have applied modern molecular tools to analyze field samples to provide an insight into the genotypic composition and diversity of the Microcystis community in the past and present day Lake …

Go to article

Soil Microbial Community Response To Hexavalent Chromium In Planted And Unplanted Soil, Ioannis Ipsilantis, Mark S. Coyne May 2007

Soil Microbial Community Response To Hexavalent Chromium In Planted And Unplanted Soil, Ioannis Ipsilantis, Mark S. Coyne

Plant and Soil Sciences Faculty Publications

Theories suggest that rapid microbial growth rates lead to quicker development of metal resistance. We tested these theories by adding hexavalent chromium [Cr(VI)] to soil, sowing Indian mustard (Brassica juncea), and comparing rhizosphere and bulk soil microbial community responses. Four weeks after the initial Cr(VI) application we measured Cr concentration, microbial biomass by fumigation extraction and soil extract ATP, tolerance to Cr and growth rates with tritiated thymidine incorporation, and performed community substrate use analysis with BIOLOG GN plates. Exchangeable Cr(VI) levels were very low, and therefore we assumed the Cr(VI) impact was transient. Microbial biomass was reduced …

Go to article

Impact Of Nutritional Supplements And Monosaccharides On Growth, Oxalate Accumulation, And Culture Ph By Sclerotinia Sclerotiorum, Steven L. Daniel, Bryan J. Culbertson, Norbert C. Furumo May 2007

Impact Of Nutritional Supplements And Monosaccharides On Growth, Oxalate Accumulation, And Culture Ph By Sclerotinia Sclerotiorum, Steven L. Daniel, Bryan J. Culbertson, Norbert C. Furumo

Steven L. Daniel

Sclerotinia sclerotiorum D-E7 was studied to determine the impact of nutritional supplements and monosaccharides on growth, oxalate accumulation, and culture pH in broth media (initial pH c. 5). Cultures with 0.1% nutritional supplement (tryptone, yeast extract, or soytone) yielded minimal growth, 2–3 mM oxalate, and a final culture pH of 4.2–4.8. In contrast, cultures with 0.1% nutritional supplement and 25 mM glucose yielded significant growth, minimal oxalate (<1 mM), and a final culture pH of 2.8–3.7. Similar trends were observed when glucose in 0.1% soytone cultures was replaced with 25 mM d-mannose, l-arabinose, or d-xylose. With 1% soytone-25 mM glucose cultures, growth and oxalate accumulation (∼21 mM) occurred with little change in initial pH. This was not the case with 1% soytone-250 mM glucose cultures; increased glucose levels resulted in a decrease in oxalate accumulation (∼7 mM) and in final culture pH (3.4). Time-course studies with these cultures revealed that oxalate accumulation was suppressed during growth when the culture pH dropped to <4. Overall, these results indicate that (1) the decrease in external pH (i.e. acidification) was independent of oxalate accumulation and (2) acidification coupled to glucose-dependent growth regulated oxalate accumulation by Sclerotinia sclerotiorum.

Go to article

Impact Of Nutritional Supplements And Monosaccharides On Growth, Oxalate Accumulation, And Culture Ph By Sclerotinia Sclerotiorum, Steven Daniel, Bryan Culbertson, Norbert Furumo May 2007

Impact Of Nutritional Supplements And Monosaccharides On Growth, Oxalate Accumulation, And Culture Ph By Sclerotinia Sclerotiorum, Steven Daniel, Bryan Culbertson, Norbert Furumo

Faculty Research & Creative Activity

Sclerotinia sclerotiorum D-E7 was studied to determine the impact of nutritional supplements and monosaccharides on growth, oxalate accumulation, and culture pH in broth media (initial pH c. 5). Cultures with 0.1% nutritional supplement (tryptone, yeast extract, or soytone) yielded minimal growth, 2–3 mM oxalate, and a final culture pH of 4.2–4.8. In contrast, cultures with 0.1% nutritional supplement and 25 mM glucose yielded significant growth, minimal oxalate (<1 mM), and a final culture pH of 2.8–3.7. Similar trends were observed when glucose in 0.1% soytone cultures was replaced with 25 mM d-mannose, l-arabinose, or d-xylose. With 1% soytone-25 mM glucose cultures, growth and oxalate accumulation (∼21 mM) occurred with little change in initial pH. This was not the case with 1% soytone-250 mM glucose cultures; increased glucose levels resulted in a decrease in oxalate accumulation (∼7 mM) and in final culture pH (3.4). Time-course studies with these cultures revealed that oxalate accumulation was suppressed during growth when the culture pH dropped to <4. Overall, these results indicate that (1) the decrease in external pH (i.e. acidification) was independent of oxalate accumulation and (2) acidification coupled to glucose-dependent growth regulated oxalate accumulation by Sclerotinia sclerotiorum.

Go to article

Impact Of Nutritional Supplements And Monosaccharides On Growth, Oxalate Accumulation, And Culture Ph By Sclerotinia Sclerotiorum, Steven L. Daniel, Bryan J. Culbertson, Norbert C. Furumo May 2007

Impact Of Nutritional Supplements And Monosaccharides On Growth, Oxalate Accumulation, And Culture Ph By Sclerotinia Sclerotiorum, Steven L. Daniel, Bryan J. Culbertson, Norbert C. Furumo

Faculty Research & Creative Activity

Sclerotinia sclerotiorum D-E7 was studied to determine the impact of nutritional supplements and monosaccharides on growth, oxalate accumulation, and culture pH in broth media (initial pH c. 5). Cultures with 0.1% nutritional supplement (tryptone, yeast extract, or soytone) yielded minimal growth, 2–3 mM oxalate, and a final culture pH of 4.2–4.8. In contrast, cultures with 0.1% nutritional supplement and 25 mM glucose yielded significant growth, minimal oxalate (<1 mM), and a final culture pH of 2.8–3.7. Similar trends were observed when glucose in 0.1% soytone cultures was replaced with 25 mM d-mannose, l-arabinose, or d-xylose. With 1% soytone-25 mM glucose cultures, growth and oxalate accumulation (∼21 mM) occurred with little change in initial pH. This was not the case with 1% soytone-250 mM glucose cultures; increased glucose levels resulted in a decrease in oxalate accumulation (∼7 mM) and in final culture pH (3.4). Time-course studies with these cultures revealed that oxalate accumulation was suppressed during growth when the culture pH dropped to <4. Overall, these results indicate that (1) the decrease in external pH (i.e. acidification) was independent of oxalate accumulation and (2) acidification coupled to glucose-dependent growth regulated oxalate accumulation by Sclerotinia sclerotiorum.

Go to article

Green Autofluorescence In Dinoflagellates, Diatoms, And Other Microalgae And Its Implications For Vital Staining And Morphological Studies, Ying Zhong Tang, Fred C. Dobbs Apr 2007

Green Autofluorescence In Dinoflagellates, Diatoms, And Other Microalgae And Its Implications For Vital Staining And Morphological Studies, Ying Zhong Tang, Fred C. Dobbs

OES Faculty Publications

Green autofluorescence (GAF) has been described in the short flagellum of golden and brown algae, the stigma of Euglenophyceae, and cytoplasm of different life stages of dinoflagellates and is considered by some researchers a valuable taxonomic feature for dinoflagellates. In addition, green fluorescence staining has been widely proposed or adopted to measure cell viability (or physiological state) in areas such as apoptosis of phytoplankton, pollutant stresses on algae, metabolic activity of algae, and testing treatment technologies for ships' ballast water. This paper reports our epifluorescence microscopic observations and quantitative spectrometric measurements of GAIT in a broad phylogenetic range of microalgae. …

Go to article

Genetic Diversity And Potential Function Of Microbial Symbionts Associated With Newly Discovered Species Of Osedax Polychaete Worms, Shana K. Goffredi, Shannon B. Johnson, Robert C. Vrijenhoek Mar 2007

Genetic Diversity And Potential Function Of Microbial Symbionts Associated With Newly Discovered Species Of Osedax Polychaete Worms, Shana K. Goffredi, Shannon B. Johnson, Robert C. Vrijenhoek

Shana Goffredi

We investigated the genetic diversity of symbiotic bacteria associated with two newly discovered species of Osedax from Monterey Canyon, CA, at 1,017-m (Osedax Monterey Bay sp. 3 “rosy” [Osedax sp. MB3]) and 381-m (Osedax Monterey Bay sp. 4 “yellow collar”) depths. Quantitative PCR and clone libraries of 16S rRNA gene sequences identified differences in the compositions and abundances of bacterial phylotypes associated with the newly discovered host species and permitted comparisons between adult Osedax frankpressi and juveniles that had recently colonized whalebones implanted at 2,891 m. The newly discovered Osedax species hosted Oceanospirillales symbionts that are related to Gammaproteobacteria associated …

Go to article

Sulfur-Oxidizing Bacteria In Soap Lake (Washington State), A Meromictic, Haloalkaline Lake With An Unprecedented High Sulfide Content, Dimitry Y. Sorokin, Mirjam Foti, Holly C. Pinkart, Gerard Muyzer Jan 2007

Sulfur-Oxidizing Bacteria In Soap Lake (Washington State), A Meromictic, Haloalkaline Lake With An Unprecedented High Sulfide Content, Dimitry Y. Sorokin, Mirjam Foti, Holly C. Pinkart, Gerard Muyzer

All Faculty Scholarship for the College of the Sciences

Culture-dependent and -independent techniques were used to study the diversity of chemolithoautotrophic sulfur-oxidizing bacteria in Soap Lake (Washington State), a meromictic, haloalkaline lake containing an unprecedentedly high sulfide concentration in the anoxic monimolimnion. Both approaches revealed the dominance of bacteria belonging to the genus Thioalkalimicrobium, which are common inhabitants of soda lakes. A dense population of Thioalkalimicrobium (up to 107 cells/ml) was found at the chemocline, which is characterized by a steep oxygen-sulfide gradient. Twelve Thioalkalimicrobium strains exhibiting three different phenotypes were isolated in pure culture from various locations in Soap Lake. The isolates fell into two groups …

Go to article

Anaerobic Oxalate Consumption By Microorganisms In Forest Soils, Steven L. Daniel, Christine Pilsl, Harold L. Drake Jan 2007

Anaerobic Oxalate Consumption By Microorganisms In Forest Soils, Steven L. Daniel, Christine Pilsl, Harold L. Drake

Steven L. Daniel

The microbial consumption of oxalate was examined under anaerobic conditions in soil suspensions at 15-20 degree C. With soil (horizon Ah, pH 6.4) from a beech forest, microbial consumption of added oxalate (15 mM) began after 10 days, and oxalate was totally consumed by day 20. The presence of supplemental electron donors (acetate, glucose, vanillate, or hydrogen) or electron acceptors (nitrate or sulfate) did not significantly influence anaerobic oxalate consumption, whereas supplementation of soil suspensions with CO2/bicarbonate totally repressed oxalate consumption. Thus, CO2-, nitrate- or sulfate-respiring bacteria were apparently not active in the anaerobic consumption of oxalate in these soil …

Go to article

Enzymes As Feed Additive To Aid In Responses Against Eimeria Species In Coccidia-Vaccinated Broilers Fed Corn-Soybean Meal Diets With Different Protein Levels, J. Parker, E. O. Oviedo Rondon, Beatrice A. Clack, S. Clemente-Hernandez, J. Osborne, J. C. Remus, H. Kettunen, H. Makivuokko, E. M. Pierson Jan 2007

Enzymes As Feed Additive To Aid In Responses Against Eimeria Species In Coccidia-Vaccinated Broilers Fed Corn-Soybean Meal Diets With Different Protein Levels, J. Parker, E. O. Oviedo Rondon, Beatrice A. Clack, S. Clemente-Hernandez, J. Osborne, J. C. Remus, H. Kettunen, H. Makivuokko, E. M. Pierson

Faculty Publications

This research aimed to evaluate the effects of adding a combination of exogenous enzymes to starter diets varying in protein content and fed to broilers vaccinated at day of hatch with live oocysts and then challenged with mixed Eimeria spp. Five hundred four 1-d-old male Cobb-500 chickens were distributed in 72 cages. The design consisted of 12 treatments. Three anticoccidial control programs [ionophore (IO), coccidian vaccine (COV), and coccidia-vaccine + enzymes (COV + EC)] were evaluated under 3 CP levels (19, 21, and 23%), and 3 unmedicated-uninfected (UU) negative controls were included for each one of the protein levels. All …

Go to article

Responses Of Rhizobia To Desiccation In Relation To Osmotic Stress, Oxygen, And Temperature, Jan A.C. Vriezen Dr., Frans J. Debruijn Dr., Klaus R. Nusslein Dr. Jan 2007

Responses Of Rhizobia To Desiccation In Relation To Osmotic Stress, Oxygen, And Temperature, Jan A.C. Vriezen Dr., Frans J. Debruijn Dr., Klaus R. Nusslein Dr.

Jan A.C. Vriezen Dr.

No abstract provided.

Go to article

Anaerobic Oxalate Consumption By Microorganisms In Forest Soils, Steven Daniel, Christine Pilsl, Harold Drake Jan 2007

Anaerobic Oxalate Consumption By Microorganisms In Forest Soils, Steven Daniel, Christine Pilsl, Harold Drake

Faculty Research & Creative Activity

The microbial consumption of oxalate was examined under anaerobic conditions in soil suspensions at 15-20 degree C. With soil (horizon Ah, pH 6.4) from a beech forest, microbial consumption of added oxalate (15 mM) began after 10 days, and oxalate was totally consumed by day 20. The presence of supplemental electron donors (acetate, glucose, vanillate, or hydrogen) or electron acceptors (nitrate or sulfate) did not significantly influence anaerobic oxalate consumption, whereas supplementation of soil suspensions with CO2/bicarbonate totally repressed oxalate consumption. Thus, CO2-, nitrate- or sulfate-respiring bacteria were apparently not active in the anaerobic consumption of oxalate in these soil …

Go to article

Anaerobic Oxalate Consumption By Microorganisms In Forest Soils, Steven L. Daniel, Christine Pilsl, Harold L. Drake Jan 2007

Anaerobic Oxalate Consumption By Microorganisms In Forest Soils, Steven L. Daniel, Christine Pilsl, Harold L. Drake

Faculty Research & Creative Activity

The microbial consumption of oxalate was examined under anaerobic conditions in soil suspensions at 15-20 degree C. With soil (horizon Ah, pH 6.4) from a beech forest, microbial consumption of added oxalate (15 mM) began after 10 days, and oxalate was totally consumed by day 20. The presence of supplemental electron donors (acetate, glucose, vanillate, or hydrogen) or electron acceptors (nitrate or sulfate) did not significantly influence anaerobic oxalate consumption, whereas supplementation of soil suspensions with CO2/bicarbonate totally repressed oxalate consumption. Thus, CO2-, nitrate- or sulfate-respiring bacteria were apparently not active in the anaerobic consumption of oxalate in these soil …

Go to article

Comparison Of Cell-Specific Activity Between Free-Living And Attached Bacteria Using Isolates And Natural Assemblages, Hp Gropssar, Kw Tang, T Kiorboe, H Ploug Jan 2007

Comparison Of Cell-Specific Activity Between Free-Living And Attached Bacteria Using Isolates And Natural Assemblages, Hp Gropssar, Kw Tang, T Kiorboe, H Ploug

VIMS Articles

Marine snow aggregates are microbial hotspots that support high bacterial abundance and activities. We conducted laboratory experiments to compare cell-specific bacterial protein production (BPP) and protease activity between free-living and attached bacteria. Natural bacterial assemblages attached to model aggregates (agar spheres) had threefold higher BPP and two orders of magnitude higher protease activity than their free-living counterpart. These observations could be explained by preferential colonization of the agar spheres by bacteria with inherently higher metabolic activity and/or individual bacteria increasing their metabolism upon attachment to surfaces. In subsequent experiments, we used four strains of marine snow bacteria isolates to test …

Go to article

Comparison Study Of The Averaged Sediment Microbial Enzyme Activities In Four Fecally-Contaminated Streams In The Same Watershed In Northeast Tennessee To Biochemical Oxygen Demand, Nitrate Concentration, And Phosphate Concentration, Brian G. Evanshen, Kurt J. Maier, Phillip R. Scheuerman Jan 2007

Comparison Study Of The Averaged Sediment Microbial Enzyme Activities In Four Fecally-Contaminated Streams In The Same Watershed In Northeast Tennessee To Biochemical Oxygen Demand, Nitrate Concentration, And Phosphate Concentration, Brian G. Evanshen, Kurt J. Maier, Phillip R. Scheuerman

ETSU Faculty Works

Microbial enzyme activities (MEA’s) are measurements of microbial metabolism. These activities are dependent on the need for nutrients and respiration. This extended study evaluated four streams in the same watershed that had an approved fecal coliform Total Maximum Daily Load. Sediment and water samples were collected monthly for the first year of each specific stream study, and then quarterly to the end of 2006. Dehydrogenase, a measure of microbial respiration, along with acid phosphatase, alkaline phosphatase, galactosidase and glucosidase activities were measured using colorimetric assays. Biochemical oxygen demand (BOD) was determined using the standard 5-day test (BOD5). Nitrate …

Go to article

Environmental Controls On The Landscape-Scale Biogeography Of Stream Bacterial Communities, Noah Fierer, Jennifer L. Morse, Sean T. Berthrong, Emily S. Bernhardt, Robert B. Jackson Jan 2007

Environmental Controls On The Landscape-Scale Biogeography Of Stream Bacterial Communities, Noah Fierer, Jennifer L. Morse, Sean T. Berthrong, Emily S. Bernhardt, Robert B. Jackson

Scholarship and Professional Work - LAS

We determined the biogeographical distributions of stream bacteria and the biogeochemical factors that best explained heterogeneity for 23 locations within the Hubbard Brook watershed, a 3000-ha forested watershed in New Hampshire, USA. Our goal was to assess the factor, or set of factors, responsible for generating the biogeographical patterns exhibited by microorganisms at the landscape scale. We used DNA fingerprinting to characterize bacteria inhabiting fine benthic organic matter (FBOM) because of their important influence on stream nutrient dynamics. Across the watershed, streams of similar pH had similar FBOM bacterial communities. Streamwater pH was the single variable most strongly correlated with …

Go to article

Runx2 Is Essential For Larval Hyobranchial Cartilage Formation In Xenopus Laevis, Ryan Kerney, Joshua Gross, James Hanken Dec 2006

Runx2 Is Essential For Larval Hyobranchial Cartilage Formation In Xenopus Laevis, Ryan Kerney, Joshua Gross, James Hanken

Ryan Kerney

The vertebrate transcription factor protein Runx2 is regarded as a “master regulator” of bone formation due to the dramatic loss of the osseous skeleton in the mouse homozygous knockout. However, Runx2 mRNA also is expressed in the pre-hypertrophic cartilaginous skeleton of the mouse and chicken, where its developmental function is largely unknown. Several tiers of Runx2 regulation exist in the mouse, any of which may account for its seeming biological inactivity during early stages of skeletogenesis. Unlike mouse and chicken, zebrafish require Runx2 function in early cartilage differentiation. The present study reveals that the earlier functional role of Runx2 in …

Go to article

Cranial Ontogeny In Philautus Silus (Anura: Ranidae: Rhacophorinae) Reveals Few Similarities With Other Direct-Developing Anurans, Ryan Kerney, Madhava Meegaskumbura, Kelum Manamendra-Arachchi, James Hanken Dec 2006

Cranial Ontogeny In Philautus Silus (Anura: Ranidae: Rhacophorinae) Reveals Few Similarities With Other Direct-Developing Anurans, Ryan Kerney, Madhava Meegaskumbura, Kelum Manamendra-Arachchi, James Hanken

Ryan Kerney

Direct development has evolved in rhaco- phorine frogs independently from other anuran lineages, thereby offering an opportunity to assess features associ- ated with this derived life history. Using a developmen- tal series of the direct-developing Philautus silus (Ranidae: Rhacophorinae) from Sri Lanka, we examine features of cranial morphology that are part of a suite of adaptations that facilitate feeding in free-living tadpoles, but have been changed or lost in other direct-developing lineages. Larval-specific upper jaw cartilages, which are absent from many non-rhacophorine direct-developing species (such as Eleutherodactylus coqui), develop in embryos of P. silus. Similarly, lower jaw cartilages ini- tially …

Go to article

Vulnerability Of Pathogenic Biofilms To Micavibrio Aeruginosavorus, Daniel Kadouri, Nel C. Venzon, George A. O'Toole Nov 2006

Vulnerability Of Pathogenic Biofilms To Micavibrio Aeruginosavorus, Daniel Kadouri, Nel C. Venzon, George A. O'Toole

Dartmouth Scholarship

The host specificity of the gram-negative exoparasitic predatory bacterium Micavibrio aeruginosavorus was examined. M. aeruginosavorus preyed on Pseudomonas aeruginosa, as previously reported, as well as Burkholderia cepacia, Klebsiella pneumoniae, and numerous clinical isolates of these species. In a static assay, a reduction in biofilm biomass was observed as early as 3 hours after exposure to M. aeruginosavorus, and an ∼100-fold reduction in biofilm cell viability was detected following a a 24-h exposure to the predator. We observed that an initial titer of Micavibrio as low as 10 PFU/well or a time of exposure to the predator as short as 30 …

Go to article

An Anaerobic Methane Oxidizing Community Of Anme-1b Archaea In Hypersaline Gulf Of Mexico Sediments, Karen Lloyd, Laura Lapham, Andreas Teske Nov 2006

An Anaerobic Methane Oxidizing Community Of Anme-1b Archaea In Hypersaline Gulf Of Mexico Sediments, Karen Lloyd, Laura Lapham, Andreas Teske

Microbiology Publications and Other Works

Sediments overlying a brine pool methane seep in the Gulf of Mexico (Green Canyon 205) were analyzed using molecular and geochemical approaches to identify geochemical controls on microbial community composition and stratification. 16S rRNA gene and rRNA clone libraries, as well as mcrA gene clone libraries, showed that the archaeal community consists predominantly of ANME-1b methane oxidizers; no archaea of other ANME subgroups were found with general and group-specific PCR primers. The ANME-1b community was found in the sulfate-methane interface, where undersaturated methane concentrations of ca. 100 to 250 _M coexist with sulfate concentrations around 10 mM. Clone libraries of …

Go to article

An Anaerobic Methane Oxidizing Community Of Anme-1b Archaea In Hypersaline Gulf Of Mexico Sediments, Karen Lloyd, Laura Lapham, Andreas Teske Nov 2006

An Anaerobic Methane Oxidizing Community Of Anme-1b Archaea In Hypersaline Gulf Of Mexico Sediments, Karen Lloyd, Laura Lapham, Andreas Teske

Karen Lloyd

Sediments overlying a brine pool methane seep in the Gulf of Mexico (Green Canyon 205) were analyzed using molecular and geochemical approaches to identify geochemical controls on microbial community composition and stratification. 16S rRNA gene and rRNA clone libraries, as well as mcrA gene clone libraries, showed that the archaeal community consists predominantly of ANME-1b methane oxidizers; no archaea of other ANME subgroups were found with general and group-specific PCR primers. The ANME-1b community was found in the sulfate-methane interface, where undersaturated methane concentrations of ca. 100 to 250 _M coexist with sulfate concentrations around 10 mM. Clone libraries of …

Go to article

Microbial Abundance, Composition And Enzymatic Activity During Decomposition Of Copepod Carcasses, Kw Tang, Kml Hutalle, Et Al Nov 2006

Microbial Abundance, Composition And Enzymatic Activity During Decomposition Of Copepod Carcasses, Kw Tang, Kml Hutalle, Et Al

VIMS Articles

Literature suggests that zooplankton carcasses are prevalent at times in both freshwater and marine environments, and could be important substrate sources for water column microbes (Dubovskaya et al. 2003, Hydrobiologia 504:223-227; Tang et al. 2006b, Estuar Coast Shelf Sci 68:499-508). We conducted laboratory experiments to investigate the decomposition of copepod carcasses by ambient microbes from Lake Dagow, Germany. Bacteria rapidly colonized and decomposed the carcasses, mainly from the inside. The ambient bacterial abundance increased 2-fold or more at the peak of decomposition, but decreased afterward, presumably due to protozoan grazing. Initial increase in ambient bacteria was faster at 20 degrees …

Go to article

First Prev Next Last