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Articles 1 - 30 of 61
Full-Text Articles in Life Sciences
Using A Machine Learning Model To Predict Plant Inflorescences Based Upon Its Soil Microbiome, Luke Denoncourt
Using A Machine Learning Model To Predict Plant Inflorescences Based Upon Its Soil Microbiome, Luke Denoncourt
Undergraduate Honors Theses
The UN estimates that the global population could reach 9.7 billion by 2050 (United Nations). As a result, the amount of food required to feed humanity is thought to double by 2050 (Ray et al., 2012). Humanity must find a way to increase crop production without increasing fertilizer usage and eutrophication, which can be done using the soil microbiome. Using potted plants with soils inoculated with Pseudomonas alcaligenes, Pseudomonas denitrificans, Bacillus polymyxa, and Mycobacterium phlei, both the shoot and root growth of pea and cotton plants was significantly increased (Egamberdieva & Höflich, 2004). In this study, utilizing a random forest …
Analysis Of Edna To Assess Effects Of Water Quality On Freshwater Fungal Diversity In A Virginia Coastal Watershed, Lauren French
Analysis Of Edna To Assess Effects Of Water Quality On Freshwater Fungal Diversity In A Virginia Coastal Watershed, Lauren French
Undergraduate Honors Theses
Freshwater fungi comprise a phylogenetically and functionally diverse group which contributes to wide-ranging ecosystem processes in aquatic systems. Saprotrophic fungi convert detritus into nutrient-rich food sources for fish and invertebrates, whereas pathogenic and parasitic fungi can cause disease and population declines of other aquatic organisms. With their diverse and important roles, changes in freshwater fungal community structure may have far-reaching impacts on ecosystems. To understand how natural and anthropogenic stressors to freshwater systems impact fungal-mediated ecosystem processes, a greater understanding of the taxonomic and functional composition of freshwater fungal communities is needed. We assessed relationships among freshwater habitat types, water …
A Mollicutes Metagenome-Assembled Genome From The Gut Of The Pteropod Limacina Rangii, Zachary T. Pimentel, Patrica S. Thibodeau, Bongkeum Song, Ying Zhang
A Mollicutes Metagenome-Assembled Genome From The Gut Of The Pteropod Limacina Rangii, Zachary T. Pimentel, Patrica S. Thibodeau, Bongkeum Song, Ying Zhang
VIMS Articles
A nearly complete genome of an uncultured Mollicutes sp. was obtained from the metagenome of the gut of Limacina rangii (open-ocean snail), an important grazer and prey for higher trophic animals along the rapidly warming region of the western Antarctic Peninsula.
Mysteries And Uncertainties In Tracing Cryptic Viral Infections, Melaina Jacoby
Mysteries And Uncertainties In Tracing Cryptic Viral Infections, Melaina Jacoby
Undergraduate Honors Theses
Viruses are the most abundant biological entities on Earth. Viral impacts are evident from the level of individual cells and population all the way up to ecosystems and global elemental cycles. Since bacteriophages (viruses that infect bacteria) were first identified in the early twentieth century, the study of these fascinating entities has shown how viral dynamics within ecosystems can influence microbially-mediated processes at a large scale. Viral infections can impact hosts and host-mediated processes in in multiple ways, one of which is through cryptic infections. This state, in which a bacterium may harbor a cryptic phage infection, is known as …
Trace Metal Availability Affects Greenhouse Gas Emissions And Microbial Functional Group Abundance In Freshwater Wetland Sediments, George Giannopoulos, Katherine R. Hartop, Bonnie L. Brown, Bongkeun Song, Lars Elsgaard, Rima B. Franklin
Trace Metal Availability Affects Greenhouse Gas Emissions And Microbial Functional Group Abundance In Freshwater Wetland Sediments, George Giannopoulos, Katherine R. Hartop, Bonnie L. Brown, Bongkeun Song, Lars Elsgaard, Rima B. Franklin
VIMS Articles
We investigated the effects of trace metal additions on microbial nitrogen (N) and carbon (C) cycling using freshwater wetland sediment microcosms amended with micromolar concentrations of copper (Cu), molybdenum (Mo), iron (Fe), and all combinations thereof. In addition to monitoring inorganic N transformations (NO3–, NO2–, N2O, NH4+) and carbon mineralization (CO2, CH4), we tracked changes in functional gene abundance associated with denitrification (nirS, nirK, nosZ), dissimilatory nitrate reduction to ammonium (DNRA; nrfA), and methanogenesis (mcrA). With regards to …
Preliminary Assessment Of Microbial Community Structure Of Wind-Tidal Flats In The Laguna Madre, Texas, Usa, I-Shuo Huang, Lee J. Pinnell, Jeffrey W. Turner, Et Al
Preliminary Assessment Of Microbial Community Structure Of Wind-Tidal Flats In The Laguna Madre, Texas, Usa, I-Shuo Huang, Lee J. Pinnell, Jeffrey W. Turner, Et Al
VIMS Articles
Aside from two samples collected nearly 50 years ago, little is known about the microbial composition of wind tidal flats in the hypersaline Laguna Madre, Texas. These mats account for ~42% of the lagoon’s area. These microbial communities were sampled at four locations that historically had mats in the Laguna Madre, including Laguna Madre Field Station (LMFS), Nighthawk Bay (NH), and two locations in Kenedy Ranch (KRN and KRS). Amplicon sequencing of 16S genes determined the presence of 51 prokaryotic phyla dominated by Bacteroidota, Chloroflexi, Cyanobacteria, Desulfobacteria, Firmicutes, Halobacteria, and Proteobacteria. The microbial community structure of NH and KR is …
Composition And Bioavailability Of Effluent Dissolved Organic Nitrogen, Quinn Nicole Roberts
Composition And Bioavailability Of Effluent Dissolved Organic Nitrogen, Quinn Nicole Roberts
Dissertations, Theses, and Masters Projects
Cultural eutrophication, the overproduction of phytoplankton biomass in response to increased nutrient inputs directly associated with human activities, is a major threat to the health of Chesapeake Bay. Strict regulations, which require a reduction in nutrient loading from all sources, have been a key component to restoration efforts. Water reclamation facilities (WRFs), which discharge effluent containing nitrogen (N) and other nutrients into receiving waters, have implemented upgrades in an effort to comply with regulations. These improvements have decreased the concentration of highly labile dissolved inorganic N (DIN), leaving behind significant concentrations of dissolved organic N (DON) whose bioavailability, and therefore …
Vertical Stratification Of Sediment Microbial Communities Along Geochemical Gradients Of A Subterranean Estuary Located At The Gloucester Beach Of Virginia, United States, Yiguo Hong, Jiapeng Wu, Stephanie Wilson, Bk Song
Vertical Stratification Of Sediment Microbial Communities Along Geochemical Gradients Of A Subterranean Estuary Located At The Gloucester Beach Of Virginia, United States, Yiguo Hong, Jiapeng Wu, Stephanie Wilson, Bk Song
VIMS Articles
Subterranean estuaries (STEs) have been recognized as important ecosystems for the exchange of materials between the land and sea, but the microbial players of biogeochemical processes have not been well examined. In this study, we investigated the bacterial and archaeal communities within 10 cm depth intervals of a permeable sediment core (100 cm in length) collected from a STE located at Gloucester Point (GP-STE), VA, United States. High throughput sequencing of 16S rRNA genes and subsequent bioinformatics analyses were conducted to examine the composition, diversity, and potential functions of the sediment communities. The community composition varied significantly from the surface …
Discerning Autotrophy, Mixotrophy And Heterotrophyin Marine Tack Archaea From The North Atlantic, L M. Seyler, L. R. Mcguinness, J. A. Gilbert, J. F. Biddle, Donglai Gong, L. J. Kerkhof
Discerning Autotrophy, Mixotrophy And Heterotrophyin Marine Tack Archaea From The North Atlantic, L M. Seyler, L. R. Mcguinness, J. A. Gilbert, J. F. Biddle, Donglai Gong, L. J. Kerkhof
VIMS Articles
DNA stable isotope probing (SIP) was used to track the uptake of organic and inorganic carbon sources for TACK archaea(Thaumarchaeota/Aigarchaeota/Crenarchaeota/Korarchaeota) on a cruise of opportunity in the North Atlantic. Due to water limitations, duplicate samples from the deep photic (60–115 m), the mesopelagic zones (local oxygen minimum; 215–835 m)and the bathypelagic zone (2085–2835 m) were amended with various combinations of12C- or13C-acetate/urea/bicarbonate to assess cellular carbon acquisition. The SIP results indicated the majority of TACK archaeal operational taxonomic units(OTUs) incorporated13C from acetate and/or urea into newly synthesized DNA within 48 h. A small fraction (16%) of the OTUs, often representing the …
Microbes As Engines Of Ecosystem Function: When Does Community Structure Enhance Predictions Of Ecosystem Processes?, Emily B. Graham, Joeseph E. Knelman, Et Al, Bk Song
Microbes As Engines Of Ecosystem Function: When Does Community Structure Enhance Predictions Of Ecosystem Processes?, Emily B. Graham, Joeseph E. Knelman, Et Al, Bk Song
VIMS Articles
Microorganisms are vital in mediating the earth’s biogeochemical cycles; yet, despite our rapidly increasing ability to explore complex environmental microbial communities, the relationship between microbial community structure and ecosystem processes remains poorly understood. Here, we address a fundamental and unanswered question in microbial ecology: ‘When do we need to understand microbial community structure to accurately predict function?’ We present a statistical analysis investigating the value of environmental data and microbial community structure independently and in combination for explaining rates of carbon and nitrogen cycling processes within 82 global datasets. Environmental variables were the strongest predictors of process rates but left …
Structure And Function Of Zooplankton-Associated Bacterial Communities In A Temperate Estuary Change More With Time Than With Zooplankton Species, Samatha L. Bickel, Kam W. Tang, Hans-Peter Grossart
Structure And Function Of Zooplankton-Associated Bacterial Communities In A Temperate Estuary Change More With Time Than With Zooplankton Species, Samatha L. Bickel, Kam W. Tang, Hans-Peter Grossart
VIMS Articles
Zooplankton support distinct bacterial communities in high concentrations relative to the surrounding water, but little is known about how the compositions and functionalities of these bacterial communities change through time in relation to environmental conditions. We conducted a year-long field study of bacterial communities associated with common zooplankton groups as well as free-living bacterial communities in the York River, a tributary of Chesapeake Bay. Bacterial community genetic fingerprints and their carbon substrate usage were examined by denaturing gradient gel electrophoresis (DGGE) of amplified 16S rDNA and by Biolog EcoPlates, respectively. Zooplankton-associated communities were genetically distinct from free-living bacterial communities but …
Impacts Of Freshwater Flushing On Anammox Community Structure And Activities In The New River Estuary, Usa, Ja Lisa, B Song, Cr Tobias, Ka Duernberger
Impacts Of Freshwater Flushing On Anammox Community Structure And Activities In The New River Estuary, Usa, Ja Lisa, B Song, Cr Tobias, Ka Duernberger
VIMS Articles
Anaerobic ammonium oxidation (anammox) and denitrification are 2 microbial nitrogen removal processes that may play an important role in controlling the intensity and duration of estuarine and coastal eutrophication. Sediment communities in the New River Estuary, North Carolina were investigated to determine the dynamics of anammox activity and community structure in conjunction with environmental conditions. N-15 tracer incubation experiments with sediment slurries were used to measure anammox and denitrification rates and estimate anammox contribution to total N-2 production. Molecular analyses targeting the hydrazine oxidoreductase (hzo) gene were conducted to examine the structure of anammox communities and quantify the abundance of …
Analyses Of Kings Creek Water And Watershed Runoff Samples For Bacteroidales Using Qpcr To Detect Human Fecal Contamination, Howard Kator, Kimberly S. Reece
Analyses Of Kings Creek Water And Watershed Runoff Samples For Bacteroidales Using Qpcr To Detect Human Fecal Contamination, Howard Kator, Kimberly S. Reece
Reports
The purpose of this work was to evaluate and analyze water samples collected from the Kings Creek watershed using a qPCR-based method to detect both total Bacteroidales and Bacteroidales reported to be associated with human fecal contamination. Quantitative real-time PCR assays were used to significantly reduce processing times and at the same time yield estimates of target concentrations. Initial efforts focused on evaluation of various Bacteroidales primer sets reported in the literature tested against human and animal fecal samples collected from the Kings Creek watershed. Most samples, both animal and human, were positive with the universal (i.e. general or total) …
Oceanic Heterotrophic Bacterial Nutrition By Semilabile Dom As Revealed By Data Assimilative Modeling, Yw Luo, M. A.M. Friedrichs, Sc Doney, Mj Church, Hw Ducklow
Oceanic Heterotrophic Bacterial Nutrition By Semilabile Dom As Revealed By Data Assimilative Modeling, Yw Luo, M. A.M. Friedrichs, Sc Doney, Mj Church, Hw Ducklow
VIMS Articles
Previous studies have focused on the role of labile dissolved organic matter (DOM) (defined as turnover time of similar to 1 d) in supporting heterotrophic bacterial production, but have mostly neglected semilabile DOM (defined as turnover time of similar to 100 to 1000 d) as a potential substrate for heterotrophic bacterial growth. To test the hypothesis that semilabile DOM supports substantial amounts of heterotrophic bacterial production in the open ocean, we constructed a 1-dimensional epipelagic ecosystem model and applied it to 3 open ocean sites: the Arabian Sea, Equatorial Pacific and Station ALOHA in the North Pacific Subtropical Gyre. The …
Comparison Of Cell-Specific Activity Between Free-Living And Attached Bacteria Using Isolates And Natural Assemblages, Hp Gropssar, Kw Tang, T Kiorboe, H Ploug
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 …
Microbial Abundance, Composition And Enzymatic Activity During Decomposition Of Copepod Carcasses, Kw Tang, Kml Hutalle, Et Al
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 …
Molecular Assays For Detecting Aphanomyces Invadans In Ulcerative Mycotic Fish Lesions, Mw Vandersea, Rw Litaker, B Yonnish,, Et Al, H Kator, Et Al
Molecular Assays For Detecting Aphanomyces Invadans In Ulcerative Mycotic Fish Lesions, Mw Vandersea, Rw Litaker, B Yonnish,, Et Al, H Kator, Et Al
VIMS Articles
The pathogenic oomycete Aphanomyces invadans is the primary etiological agent in ulcerative mycosis, an ulcerative skin disease caused by a fungus-like agent of wild and cultured fish. We developed sensitive PCR and fluorescent peptide nucleic acid in situ hybridization (FISH) assays to detect A. invadans. Laboratory-challenged killifish (Fundulus heteroclitus) were first tested to optimize and validate the assays. Skin ulcers of Atlantic menhaden (Brevoortia tyrannus) from populations found in the Pamlico and Neuse River estuaries in North Carolina were then surveyed. Results from both assays indicated that all of the lesioned menhaden (n = 50) collected in September 2004 were …
Interactions Between Marine Snow And Heterotrophic Bacteria: Aggregate Formation And Microbial Dynamics, Hp Grossart, T Kiorboe, Kw Tang, Et Al
Interactions Between Marine Snow And Heterotrophic Bacteria: Aggregate Formation And Microbial Dynamics, Hp Grossart, T Kiorboe, Kw Tang, Et Al
VIMS Articles
Macroscopic aggregates (marine snow) contribute to new production and nutrient dynamics in the upper ocean and vertical fluxes of organic matter to the deep ocean. To test whether microorganisms play a significant role in phytoplankton aggregate formation we studied particle abundance and size as well as abundance, colonization behaviour, and community composition of bacteria during the growth of 2 marine diatoms (Thalassiosira weissflogii and Navicula sp.) under axenic and non-axenic conditions. Community composition of free-living and attached bacteria during phytoplankton growth and aggregation was studied by amplification of 16S rRNA gene fragments and denaturing gradient gel electrophoresis (DGGE). Our results …
Mycobacterium Pseudoshottsii Sp Nov., A Slowly Growing Chromogenic Species Isolated From Chesapeake Bay Striped Bass (Morone Saxatilis), Mw Rhodes, H Kator, Et Al, I Kaattari, Kimberly S. Reece, Wolfgang K. Vogelbein, Ca Ottinger
Mycobacterium Pseudoshottsii Sp Nov., A Slowly Growing Chromogenic Species Isolated From Chesapeake Bay Striped Bass (Morone Saxatilis), Mw Rhodes, H Kator, Et Al, I Kaattari, Kimberly S. Reece, Wolfgang K. Vogelbein, Ca Ottinger
VIMS Articles
A group of slowly growing photochromogenic mycobacteria was isolated from Chesapeake Bay striped bass (Morone saxatilis) during an epizootic of mycobacteriosis. Growth characteristics, acid-fastness and 16S rRNA gene sequencing results were consistent with those of the genus Mycobacterium, Biochemical reactions, growth characteristics and mycolic acid profiles (HPLC) resembled those of Mycobacterium shottsii, a non-pigmented mycobacterium also isolated during the same epizootic. Sequencing of the 16S rRNA genes, the gene encoding the exported repeated protein (erp) and the gene encoding the 65 kDa heat-shock protein (hsp65) and restriction enzyme analysis of the hsp65 gene demonstrated that this group of isolates is …
Copepods As Microbial Hotspots In The Ocean: Effects Of Host Feeding Activities On Attached Bacteria, Kw Tang
Copepods As Microbial Hotspots In The Ocean: Effects Of Host Feeding Activities On Attached Bacteria, Kw Tang
VIMS Articles
Through ingestion a copepod introduces rich organic substrates into its guts and fecal pellets, where dense bacteria may exploit them and show fast growth. Thus, a copepod and its fecal pellets may be regarded as microbial hotspots in the ocean. This study investigated the effects of copepods' feeding activities on the associated bacteria, using the Most Probable Number (MPN) method. Starved Acartia tonsa (calanoid copepod) carried a background bacteria population of 103 to 10(4) copepod(-1). When fed axenic cultures of algae Rhodomonas salina or Dunaliella tertiolecta, the bacterial abundance increased curvilinearly with the copepods' ingestion rates. When fed axenic cultures …
Real-Time Pcr For Detection And Quantification Of The Protistan Parasite Perkinsus Marinus In Environmental Waters, Corinne Audemard, Kimberly S. Reece, Em Burreson
Real-Time Pcr For Detection And Quantification Of The Protistan Parasite Perkinsus Marinus In Environmental Waters, Corinne Audemard, Kimberly S. Reece, Em Burreson
VIMS Articles
The protistan parasite Perkinsus marinus is a severe pathogen of the oyster Crassostrea virginica along the east coast of the United States. Very few data have been collected, however, on the abundance of the parasite in environmental waters, limiting our understanding of P. marinus transmission dynamics. Real-time PCR assays with SybrGreen I as a label for detection were developed in this study for quantification of P. marinus in environmental waters with P. marinus species-specific primers and of Perkinsus spp. with Perkinsus genus-specific primers. Detection of DNA concentrations as low as the equivalent of 3.3 x 10(-2) cell per 10-mul reaction …
Dinitrogen Fixation And Release Of Ammonium And Dissolved Organic Nitrogen By Trichodesmium Ims101, Mr Mulholland, Da Bronk, Dg Capone
Dinitrogen Fixation And Release Of Ammonium And Dissolved Organic Nitrogen By Trichodesmium Ims101, Mr Mulholland, Da Bronk, Dg Capone
VIMS Articles
Two methods used to measure dinitrogen (N-2) fixation (acetylene reduction and N-15(2) uptake) often result in different N-2 fixation rates. Part of the discrepancy may arise from the observation that Trichodesmium can release a fraction of their recently fixed N-2 as dissolved organic nitrogen (DON) and/or ammonium (NH4+). To resolve outstanding issues regarding N-2 fixation and the production of dissolved combined nitrogen (N) by Trichodesmium, we conducted a comprehensive analysis of N-2 fixation and the production of DON and NH4+ in cultures of Trichodesmium IMS101. We performed N-15(2) uptake experiments in parallel with acetylene (C2H2) reduction assays, and measured production …
Light Dependence Of [H-3]Leucine Incorporation In The Oligotrophic North Pacific Ocean, Mj Church, Hw Ducklow, Da Karl
Light Dependence Of [H-3]Leucine Incorporation In The Oligotrophic North Pacific Ocean, Mj Church, Hw Ducklow, Da Karl
VIMS Articles
The influence of irradiance on bacterial incorporation of [H-3] leucine was evaluated at Station ALOHA in the oligotrophic North Pacific subtropical gyre. Six experiments were conducted on three cruises to Station ALOHA to examine how [H-3]leucine incorporation varied as a function of irradiance. Two experiments were also conducted to assess the photoautotrophic response to irradiance (based on photosynthetic uptake of [C-14] bicarbonate) in both the upper and lower photic zones. Rates of [H-3]leucine incorporation responded to irradiance in a photosynthesis-like manner, increasing sharply at low light and then saturating and sometimes declining with increasing light intensity. The influence of irradiance …
Particle-Associated Flagellates: Swimming Patterns, Colonization Rates, And Grazing On Attached Bacteria, T Kiorboe, Hp Grossart, H Ploug, K Tang, B Auer
Particle-Associated Flagellates: Swimming Patterns, Colonization Rates, And Grazing On Attached Bacteria, T Kiorboe, Hp Grossart, H Ploug, K Tang, B Auer
VIMS Articles
Some pelagic flagellates colonize particles, such as marine snow, where they graze on bacteria and thus impact the dynamics of the attached microbial communities. Particle colonization is governed by motility. Swimming patterns of 2 particle-associated flagellates, Bodo designis and Spumella sp., are very different, the former swimming slowly in an erratic, random pattern, and the latter faster and along smooth helixes of variable amplitude and frequency. At spatial scales exceeding ca. 50 mum, the motility of B. designis can be described as a random walk and modeled as diffusion. Spumella sp. shows directional persistence of the helical axes up to …
Mycobacterium-Inducible Nramp In Striped Bass (Morone Saxatilis), Erin J. Burge, David T. Gauthier, Christopher A. Ottinger, Peter A. Van Veld
Mycobacterium-Inducible Nramp In Striped Bass (Morone Saxatilis), Erin J. Burge, David T. Gauthier, Christopher A. Ottinger, Peter A. Van Veld
VIMS Articles
In mammals, the natural resistance-associated macrophage protein 1 gene, Nramp1, plays a major role in resistance to mycobacterial infections. Chesapeake Bay striped bass (Morone saxatilis) is currently experiencing an epizootic of mycobacteriosis that threatens the health of this ecologically and economically important species. In the present study, we characterized an Nramp gene in this species and obtained evidence that there is induction following Mycobacterium exposure. The striped bass Nramp gene (MsNramp) and a 554-amino-acid sequence contain all the signal features of the Nramp family, including a topology of 12 transmembrane domains (TM), the transport protein-specific binding-protein-dependent transport system inner membrane …
Supplementation Of Perkinsus Marinus Cultures With Host Plasma Or Tissue Homogenate Enhances Their Infectivity, Cg Earnhart, M. A. Vogelbein, Gd Brown, Ks Reece, Sl Kaattari
Supplementation Of Perkinsus Marinus Cultures With Host Plasma Or Tissue Homogenate Enhances Their Infectivity, Cg Earnhart, M. A. Vogelbein, Gd Brown, Ks Reece, Sl Kaattari
VIMS Articles
The protozoan oyster parasite Perkinsus marinas can be cultured in vitro in a variety of media; however, this has been associated with a rapid attenuation of infectivity. Supplementation of defined media with products of P. marinus-susceptible (Crassostrea virginica) and -tolerant (Crassostrea gigas, Crassostrea ariakensis) oysters alters proliferation and protease expression profiles and induces differentiation into morphological forms typically seen in vivo. It was not known if attenuation could be reversed by host extract supplementation. To investigate correlations among these changes as well as their association with infectivity, the effects of medium supplementation with tissue homogenates from both susceptible and tolerant …
Trophic Uptake And Transfer Of Dmsp In Simple Planktonic Food Chains, Kw Tang, R Simo
Trophic Uptake And Transfer Of Dmsp In Simple Planktonic Food Chains, Kw Tang, R Simo
VIMS Articles
Recent field studies suggest that a large portion of phytoplankton-DMSP could be lost to grazing by protozoans, but the fate of the grazed DMSP remains uncertain. In the laboratory we studied trophic uptake and transfer of phytoplankton-DMSP through simple planktonic food chains using 2 experimental approaches: (1) A direct approach measured the ingestion and retention of phytoplankton-DMSP by the heterotrophic dinoflagellate Gyrodinium dominans. Overall, DMSP content of G. dominans estimated by the direct approach was highly variable, likely because of the low G. dominans biomass relative to phytoplankton in the samples. (2) An indirect approach, in which the omnivorous copepod …
Bacterioplankton Dynamics In The York River Estuary: Primary Influence Of Temperature And Freshwater Inputs, G. E. Schultz, E. D. White, H. W. Ducklow
Bacterioplankton Dynamics In The York River Estuary: Primary Influence Of Temperature And Freshwater Inputs, G. E. Schultz, E. D. White, H. W. Ducklow
VIMS Articles
Bacterial community dynamics were investigated over seasonal and basin scales within the York River estuary, Virginia. Variables describing bacterioplankton dynamics were measured at 6 stations spanning the entire salinity gradient (0 to ca. 20 psu over 60 km). Samples were collected monthly from June 1996 through May 1997 and every other month from June 1997 through May 1998. Bacterial abundance and production were high throughout the estuary. Bacterial abundance ranged from 4.4 x 10(8) to 1.3 x 10(10) cells l(-1). Incorporation of (3)H-thymidine ranged from 10 to 863 pmol(-1) h(-1) while (3)H-leucine incorporation rates ranged from 25 to 1963 pmol …
Widespread Distribution In Polar Oceans Of A 16s Rrna Gene Sequence With Affinity To Nitrosospira-Like Ammonia-Oxidizing Bacteria, Jt Hollibaugh, Hw Ducklow, N Bano
Widespread Distribution In Polar Oceans Of A 16s Rrna Gene Sequence With Affinity To Nitrosospira-Like Ammonia-Oxidizing Bacteria, Jt Hollibaugh, Hw Ducklow, N Bano
VIMS Articles
We analyzed the phylogenetic compositions of ammonia-oxidizing bacteria of the beta subclass of Proteobacteria from 42 Southern Ocean samples. We found a Nitrosospira-like 16S rRNA gene sequence in all 20 samples that yielded PCR products (8 of 30 samples from the Ross Sea and 12 of 12 samples from the Palmer Peninsula). We also found this sequence in Arctic Ocean samples, indicating a transpolar, if not global, distribution; however, slight differences between Arctic and Antarctic sequences may be evidence of polar endemism.
Photochemical Production Of Dissolved Inorganic Nitrogen And Primary Amines From Dissolved Organic Nitrogen In Waters Of Two Estuaries And Adjacent Surficial Groundwaters, Dj Koopmans, Da Bronk
Photochemical Production Of Dissolved Inorganic Nitrogen And Primary Amines From Dissolved Organic Nitrogen In Waters Of Two Estuaries And Adjacent Surficial Groundwaters, Dj Koopmans, Da Bronk
VIMS Articles
Recent studies have shown that in a number of humic-rich surface waters in North America, NH4+ is released when dissolved organic matter (DOM) is exposed to sunlight. However, photochemical NH4+ production has not been observed in all surface waters, and factors that contribute to it are not well understood. We hypothesized that the presence or absence of NH4+ photoproduction may be affected by the light exposure history of DOM, The present study was undertaken to determine whether DOM from surficial groundwaters, with minimal light exposure history, would produce labile nitrogen (N) photoproducts more consistently, In this study, estuarine surface waters …