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- Aquatic toxicology (7)
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Articles 1 - 30 of 84
Full-Text Articles in Physical Sciences and Mathematics
Advancing Computational Toxicology In A Regulatory Setting: A Selected Review Of The Accomplishments Of Gilman D. Veith (1944–2013), Steven P. Bradbury, Christine L. Russom, Patricia K. Schmieder, Terry W. Schultz, Robert Diderich, Charles M. Auer
Advancing Computational Toxicology In A Regulatory Setting: A Selected Review Of The Accomplishments Of Gilman D. Veith (1944–2013), Steven P. Bradbury, Christine L. Russom, Patricia K. Schmieder, Terry W. Schultz, Robert Diderich, Charles M. Auer
Steven P. Bradbury
With the passing of Dr. Gilman D. Veith on August 18, 2013, the research community lost one of its true visionaries in the development and implementation of alternative in silico and in vitro toxicology models in human health and ecological risk assessment. His career spanned more than four decades, during which he repeatedly demonstrated vision and leadership to advance alternative testing and assessment research and to guide the adoption of research accomplishments into U.S. and international chemical regulatory programs. His ability to advance toxicological and environmental exposure research, and associated quantitative structure– activity relationships (QSARs), for application in environmental regulatory …
Evaluation Of Trophic Niche Overlap Between Native Fishes And Young-Of-The-Year Common Carp, Michael J. Weber, Jessica M. Howell, Michael L. Rown
Evaluation Of Trophic Niche Overlap Between Native Fishes And Young-Of-The-Year Common Carp, Michael J. Weber, Jessica M. Howell, Michael L. Rown
Michael J Weber Dr
Common carp Cyprinus carpio is a ubiquitous invasive species that commonly imposes negative effects on aquatic ecosystems. However, research evaluating the effects of carp on native fishes is limited. Carp are highly fecund and larvae and juveniles can be abundant. If age-0 carp use similar prey resources as native fishes, they may compete if food becomes limited. We used traditional diet analysis for samples during Jul. and Aug. 2008 in Brant Lake. Stable sotopes were used for samples collected during Aug. and Sep. 2009 in Brant Lake and Lake Sinai to examine prey resource use by age-0 carp and four …
Continuous, Pulsed And Disrupted Nutrient Subsidy Effects On Ecosystem Productivity, Stability, And Energy Flow, Michael J. Weber, Michael L. Brown
Continuous, Pulsed And Disrupted Nutrient Subsidy Effects On Ecosystem Productivity, Stability, And Energy Flow, Michael J. Weber, Michael L. Brown
Michael J Weber Dr
Resource pulses and subsidies can supply ecosystems with an important source of nutrients that supports additional productivity at multiple trophic levels. Common carp Cyprinus carpio provide ecosystems with a continuous nutrient subsidy through bioturbation and excretion but may also initiate a nutrient pulse through carcass decomposition. We examined how continuous (common carp foraging and excretion), pulsed (carcass decomposition) and disrupted (carp introduced and then removed) nutrient subsidies differed in their ability to alter nutrient availability, ecosystem productivity and stability and energy flow. Nitrogen and phosphorus availability and primary production were highest in pulsed, intermediate in continuous and lowest for disrupted …
Predicting Modes Of Toxic Action From Chemical Structure, Steven P. Bradbury, Christine L. Russom, Steven J. Broderius, Dean J. Hammermeister, Robert A. Drummond, Gilman D. Veith
Predicting Modes Of Toxic Action From Chemical Structure, Steven P. Bradbury, Christine L. Russom, Steven J. Broderius, Dean J. Hammermeister, Robert A. Drummond, Gilman D. Veith
Steven P. Bradbury
Like many of the papers in the Environmental Toxicology and Chemistry “Top 100” list, the development of the fathead minnow database [1] and the assignment of modes of action to the 617 chemicals therein resulted from a comprehensive research effort by a multidisciplinary team of researchers with expertise in quantitative structure–activity relationship (QSAR) modeling, chemistry, toxicokinetics, joint toxicity of chemical mixtures, and behavioral and aquatic toxicology. The fathead minnow database was the culmination of the US Environmental Protection Agency’s (USEPA) QSAR research program, which spanned nearly 20 yr, a rare program because many research planning efforts typically run within a …
Genetic Analysis Of The Federally Endangered Winged Mapleleaf Mussel To Aid Proposed Re-Introduction Efforts, Kevin J. Roe
Genetic Analysis Of The Federally Endangered Winged Mapleleaf Mussel To Aid Proposed Re-Introduction Efforts, Kevin J. Roe
Kevin J. Roe
The winged mapleleaf, Quadrula fragosa, historically occurred in the Mississippi, Tennessee, Ohio, and Cumberland river drainages, but has suffered severe population and range reductions. At the time that the species was federally listed as endangered, its range was thought to have been reduced to a stretch of the St. Croix River between northwestern Wisconsin and east-central Minnesota. Recently, morphologically “Q. fragosa-like” specimens were discovered at sites in Arkansas (Ouachita River and Saline River), Missouri (Bourbeuse River), and Oklahoma (Little River). Subsequently, a plan was proposed to re-introduce Q. fragosa into portions of its historic range where its been extirpated from …
Application Of The Tissue Residue Approach In Ecological Risk Assessment, Steven P. Bradbury, Keith G. Sappington, Todd S. Bridges, Russell J. Erickson, A. Jan Hendriks, Roman P. Lanno, James P. Meador, David R. Mount, Mike H. Salazar, Doug J. Spry
Application Of The Tissue Residue Approach In Ecological Risk Assessment, Steven P. Bradbury, Keith G. Sappington, Todd S. Bridges, Russell J. Erickson, A. Jan Hendriks, Roman P. Lanno, James P. Meador, David R. Mount, Mike H. Salazar, Doug J. Spry
Steven P. Bradbury
The objective of this work is to present a critical review of the application of the tissue residue approach (TRA) in ecological risk and/or impact assessment (ERA) of chemical stressors and environmental criteria development. A secondary goal is to develop a framework for integrating the TRA into ecological assessments along with traditional, exposure concentration-based assessment approaches. Although widely recognized for its toxicological appeal, the utility of the TRA in specific applications will depend on numerous factors, such as chemical properties, exposure characteristics, assessment type, availability of tissue residue-response data, and ability to quantify chemical exposure. Therefore, the decision to use …
Meeting The Common Needs Of A More Effective And Efficient Testing And Assessment Paradigm For Chemical Risk Management, Steven P. Bradbury, Vicki Dellarco, Tala Henry, Phil Sayre, Jennifer Seed
Meeting The Common Needs Of A More Effective And Efficient Testing And Assessment Paradigm For Chemical Risk Management, Steven P. Bradbury, Vicki Dellarco, Tala Henry, Phil Sayre, Jennifer Seed
Steven P. Bradbury
Significant advances have been made in human health and ecological risk assessment over the last decade. Substantial challenges, however, remain in providing credible scientific information in a timely and efficient manner to support chemical risk assessment and management decisions. A major challenge confronting risk managers is the need for critical information to address risk uncertainties in large chemical inventories such as high- and medium-production-volume industrial chemicals or pesticide inert ingredients. From a strategic and tactical viewpoint, an integrated approach that relies on all existing knowledge and uses a range of methods, including those from emerging and novel technologies, is needed …
Application Of Genomics To Regulatory Ecological Risk Assessments For Pesticides, Steven P. Bradbury, Sigmund J. Degitz, Robert A. Hoke, Richard Brennan, Lee Ferguson, Rebecca Klaper, Laszlo Orban, David Spurgeon, Susan Tilton
Application Of Genomics To Regulatory Ecological Risk Assessments For Pesticides, Steven P. Bradbury, Sigmund J. Degitz, Robert A. Hoke, Richard Brennan, Lee Ferguson, Rebecca Klaper, Laszlo Orban, David Spurgeon, Susan Tilton
Steven P. Bradbury
Substantial advances in human health and ecological risk assessment have been achieved by the risk assessment community; however, challenges remain, such as providing credible scientific information on a timely, efficient basis to support decisions for industrial chemicals and pesticides. Current risk assessment data generation requirements-including animal welfare concerns and the volume, appropriateness, and cost of required data-and the large number of chemicals requiring evaluation are a challenge confronting the chemical industry, national and international regulatory agencies, and associated stakeholders (Bradbury et al. 2004). The lack of hazard data for many chemicals and the need to improve the efficiency and quality …
Toxic Responses Of The Fish Nervous System, Steven P. Bradbury, Richard W. Carlson, Tala R. Henry, Stephanie Padilla, John Cowden
Toxic Responses Of The Fish Nervous System, Steven P. Bradbury, Richard W. Carlson, Tala R. Henry, Stephanie Padilla, John Cowden
Steven P. Bradbury
Few of the approximately 70,000 chemicals on the Toxic Substances Control Act inventory or the 1000 to 1600 new chemicals introduced each year in the United States have been tested for neurotoxicity to support risk assessments (NRC, 1992), even though it is estimated that 5 to 10% of them are likely to be neurotoxic. Neurotoxicity has been defined as adverse effects of physical, biological, or chemical agents on the structure or function of the nervous system in developing or adult organisms (Philbert et al., 2000). From a human health risk assessment perspective, the potential for neurotoxic effects associated with synthetic …
Farming Systems Research On Crop Diversification, Tillage, And Management Effects On Yield, Pests, And Environmental Quality In A Semi-Arid Environment, Andrew W. Lenssen, U. Sainju, T. Caesar-Tonthat, B. Allen, R. Lartey
Farming Systems Research On Crop Diversification, Tillage, And Management Effects On Yield, Pests, And Environmental Quality In A Semi-Arid Environment, Andrew W. Lenssen, U. Sainju, T. Caesar-Tonthat, B. Allen, R. Lartey
Andrew W. Lenssen
Available water, depleted soil quality, and weed competition are important constraints to crop production in the northern Great Plains. The traditional rotation in the region has been spring wheat with summer fallow, which is used to accrue additional soil moisture for the subsequent wheat crop. Tillage during fallow periods controls weeds, which otherwise would use substantial amounts of water and inorganic nitrogen, decreasing the efficiency of fallow and increasing soil erosion. Chemical fallow and zero tillage systems improve soil water status for subsequent crops (Lenssen et al., 2007a), allowing for increased cropping intensity and improved nutrient cycling (Lenssen et al., …
Incorporating Targeted Grazing Into Farming Systems, Andrew W. Lenssen, Patrick Hatfield, Hayes Goosey, Sue Blodgett
Incorporating Targeted Grazing Into Farming Systems, Andrew W. Lenssen, Patrick Hatfield, Hayes Goosey, Sue Blodgett
Andrew W. Lenssen
When incorporating targeted grazing into farming systems, livestock producers and farm operators need assurance that the benefits from their activities are worth their investments. This chapter will focus on how integrating grazing, particularly with sheep and goats, into farming systems can offer those benefits. The concepts are not new. Cropping systems were once integrated with livestock production: Livestock gained forage value from crop aftermath, crops were grown to sustain livestock, and livestock were used as implements to produce crops. Today, few cropping systems include livestock. Sheep and goats are traditionally produced on rangelands or pasture forages and supplemented during winter …
The Ivory-Billed Woodpecker In Mississippi?, Stephen J. Dinsmore
The Ivory-Billed Woodpecker In Mississippi?, Stephen J. Dinsmore
Stephen J Dinsmore
In April the environmental community received a real surprise--the Ivory-billed Woodpecker, long thought to be extinct, had apparently been rediscovered in Arkansas! As the news unfolded, the world learned that a team of researchers had been tracking at least one woodpecker, a lone male, for more than a year in the Cache River region of east-central Arkansas. The rediscovery of a bird presumed extinct for more than 60 years subsequently galvanized the environmental community and garnered much-needed support for the preservation of the Southeast's remaining old growth bottomland forests and endangered species recovery.
Waterfowl Abundance And Distribution In The Mississippi Delta, Stephen J. Dinsmore, Aaron T. Pearse, Richard M. Kaminski, Kenneth J. Reinecke
Waterfowl Abundance And Distribution In The Mississippi Delta, Stephen J. Dinsmore, Aaron T. Pearse, Richard M. Kaminski, Kenneth J. Reinecke
Stephen J Dinsmore
During mornings of empty skies, a duck hunter has plenty of time to ponder the question, "Where are all the ducks?" Invariable, the distraught hunter arrives at an unhappy conclusion: the ducks are not going to show up, so they must be elsewhere. The typical progression of an unsuccessful morning of hunting leads to multiple explanations as to why there weren't any ducks, such as mild winter temperatures in and north of Mississippi, not enough rain to attract ducks, too much rain and the ducks are scattered, the region doesn't have enough food to attract and hold ducks, the ducks …
Hamiota, A New Genus Of Freshwater Mussel (Bivalvia: Unionidae) From The Gulf Of Mexico Drainages Of The Southeastern United States, Kevin J. Roe, Paul D. Hartfield
Hamiota, A New Genus Of Freshwater Mussel (Bivalvia: Unionidae) From The Gulf Of Mexico Drainages Of The Southeastern United States, Kevin J. Roe, Paul D. Hartfield
Kevin J. Roe
Hamiota, a new genus of freshwater mussel containing four species formerly assigned to the genus Lampsilis Rafinesque, 1820, is described. In addition to the genus Lampsilis, members of Hamiota had previously been placed in the genera Villosa Frierson, 1927, and Ligumia Swainson, 1840. Several characters including the packaging of their larvae in a superconglutinate lure to attract host fishes, placement and shape of the marsupia, and release of glochidia through the excurrent siphon, support the recognition of these species as a distinct genus.
Meeting The Scientific Needs Of Ecological Risk Assessment In A Regulatory Context, Steven P. Bradbury, Tom C. Feitel, Cornelis J. Van Leeuwen
Meeting The Scientific Needs Of Ecological Risk Assessment In A Regulatory Context, Steven P. Bradbury, Tom C. Feitel, Cornelis J. Van Leeuwen
Steven P. Bradbury
During the past decade, the field of ecological risk assessment has progressed considerably. Advances have come from such international bodies as the Organisation for Economic Co-operation and Development (OECD), the World Health Organisation (WHO), the European and Mediterranean Plant Protection Organisation (EPPO), and the European Centre for Ecotoxicology and Toxicology of Chemicals (ECETOC) (1–8). Risk assessments have played a critical role in the development of various regulations within the European Commission (EC) as well as in other parts of the world, including the United States, Canada, and Japan (9–17). But scientists and regulators are faced with three significant challenges: streamlining …
A Correlation Study Of Wind Speeds At Norski Runs And Valders Hall Of Science, Paul D. B. Skrade, Dale M. Nimrod
A Correlation Study Of Wind Speeds At Norski Runs And Valders Hall Of Science, Paul D. B. Skrade, Dale M. Nimrod
Paul D. B. Skrade
1976 and 1977 wind speeds were recorded from the roof of Valders Hall of Science, Luther College, Decorah, Iowa in a correlation study of wind-sun energy. Summer 2004 wind speeds and directions were recorded with the hopes of correlating the speeds at Valders Hall of Science and at Norski Runs, Chattahoochie County Park, Decorah, Iowa, a site for a potential Luther College wind farm. Motivation behind the study was to determine if topology of Upper Iowa River Valley affected wind speeds.
Linear And Nonlinear Effects Of Habitat Structure On Composition And Abundance In The Macroinvertebrate Community Of A Large River, Timothy W. Stewart, Tammy L. Shumaker, Thomas A. Radzio
Linear And Nonlinear Effects Of Habitat Structure On Composition And Abundance In The Macroinvertebrate Community Of A Large River, Timothy W. Stewart, Tammy L. Shumaker, Thomas A. Radzio
Timothy W. Stewart
We used an experiment and regression analyses to quantify effects of spatial variation in habitat structure abundance on a riverine macroinvertebrate community under winter conditions. Concrete slabs (0.21 m2; n 5 24) with different numbers of stones (mean individual stone surface area 5 6.44 cm2) attached to upper faces were placed in the James River and retrieved after 28 d. Macroinvertebrate abundance and taxonomic richness on slabs were significantly positively related to stone abundance. Total macroinvertebrate abundance and abundance of oligochaetes (Nais spp.), Asiatic clams (Corbicula fluminea), caddisflies (Leptoceridae), riffle beetles (Elmidae) and stoneflies (Strophopteryx sp.) were linearly related to …
Seventy Years Of Forest Change In The Northern Great Lakes Region, Usa, Lisa A. Schulte-Moore, Thomas R. Crow, Dave Cleland
Seventy Years Of Forest Change In The Northern Great Lakes Region, Usa, Lisa A. Schulte-Moore, Thomas R. Crow, Dave Cleland
Lisa A. Schulte Moore
The rates and magnitudes of forest change have important social and economic implications. We address facets of change associated with 20th century recovery of the U.S. Lake States (Michigan, Wisconsin, and Minnesota) forests from the Great Cutover, and discuss ecological and socioeconomic implications for future forest resources.
Overview Of Data And Conceptual Approaches For Derivation Of Quantitative Structure-Activity Relationships For Ecotoxicological Effects Of Organic Chemicals, Steven P. Bradbury, Christine L. Russom, Gerald T. Ankley, T. Wayne Schultz, John D. Walker
Overview Of Data And Conceptual Approaches For Derivation Of Quantitative Structure-Activity Relationships For Ecotoxicological Effects Of Organic Chemicals, Steven P. Bradbury, Christine L. Russom, Gerald T. Ankley, T. Wayne Schultz, John D. Walker
Steven P. Bradbury
The use of quantitative structure–activity relationships (QSARs) in assessing potential toxic effects of organic chemicals on aquatic organisms continues to evolve as computational efficiency and toxicological understanding advance. With the everincreasing production of new chemicals, and the need to optimize resources to assess thousands of existing chemicals in commerce, regulatory agencies have turned to QSARs as essential tools to help prioritize tiered risk assessments when empirical data are not available to evaluate toxicological effects. Progress in designing scientifically credible QSARs is intimately associated with the development of empirically derived databases of well-defined and quantified toxicity endpoints, which are based on …
Qsar Prioritization Of Chemical Inventories For Endocrine Disruptor Testing, Steven P. Bradbury, Patricia Schmeider, Ovanes Mekenyan, Gilman Veith
Qsar Prioritization Of Chemical Inventories For Endocrine Disruptor Testing, Steven P. Bradbury, Patricia Schmeider, Ovanes Mekenyan, Gilman Veith
Steven P. Bradbury
Binding affinity between chemicals and the estrogen receptor (ER) serves as an indicator of the potential to cause endocrine disruption through this receptor-mediated endocrine pathway. Estimating ER-binding affinity is, therefore, one strategic approach to reducing the costs of screening chemicals for potential risks of endocrine disruption. While measuring ER binding with in vitro assays may be the first choice in prioritizing chemicals for additional in vitro or in vivo estrogenicity testing, the time and costs associated with screening thousands of chemicals is prohibitive. Recent advances in 3D modeling of the reactivity of flexible structures make in silico methods for estimating …
An Overview Of The Use Of Quantitative Structure-Activity Relationships For Ranking And Prioritzing Large Chemical Inventories For Environmental Risk Assessments, Steven P. Bradbury, Christine L. Russom, Roger L. Breton, John D. Walker
An Overview Of The Use Of Quantitative Structure-Activity Relationships For Ranking And Prioritzing Large Chemical Inventories For Environmental Risk Assessments, Steven P. Bradbury, Christine L. Russom, Roger L. Breton, John D. Walker
Steven P. Bradbury
Ecological risk assessments for chemical stressors are used to establish linkages between likely exposure concentrations and adverse effects to ecological receptors. At times, it is useful to conduct screening risk assessments to assist in prioritizing or ranking chemicals on the basis of potential hazard and exposure assessment parameters. Ranking of large chemical inventories can provide evidence for focusing research and/or cleanup efforts on specific chemicals of concern. Because of financial and time constraints, data gaps exist, and the risk assessor is left with decisions on which models to use to estimate the parameter of concern. In this review, several methods …
Influence Of Suspended Solids On Acute Toxicity Of Carbofuran To Daphnia Magna: Ii. An Evaluation Of Potential Interactive Mechanisms, Steven P. Bradbury, Carl Herbrandson, Deborah L. Swackhamer
Influence Of Suspended Solids On Acute Toxicity Of Carbofuran To Daphnia Magna: Ii. An Evaluation Of Potential Interactive Mechanisms, Steven P. Bradbury, Carl Herbrandson, Deborah L. Swackhamer
Steven P. Bradbury
It has been demonstrated that simultaneous exposure of Daphnia magna to suspended solids and a carbamate pesticide potentiates the toxic response to the pesticide. The toxicodynamics between these stressors were investigated to determine possible mechanisms of interaction. Three experimental series were conducted with D. magna to determine: the effect of food availability on carbofuran toxicity; the effect of food availability on jointly administered carbofuran and suspended solids; and changes in the magnitude of effects which can occur with suspended solids of different composition. These experiments demonstrated that both carbofuran toxicity and the joint toxicity of carbofuran and suspended solids to …
Quantitative Structure-Activity Relationship Models For Prediction Of Estrogen Receptor Binding Affinity Of Structurally Diverse Chemicals, Steven P. Bradbury, Patricia K. Schmeider, Gerald Ankley, Ovanes Mekenyan, John D. Walker
Quantitative Structure-Activity Relationship Models For Prediction Of Estrogen Receptor Binding Affinity Of Structurally Diverse Chemicals, Steven P. Bradbury, Patricia K. Schmeider, Gerald Ankley, Ovanes Mekenyan, John D. Walker
Steven P. Bradbury
The demonstrated ability of a variety of structurally diverse chemicals to bind to the estrogen receptor has raised the concern that chemicals in the environment may be causing adverse effects through interference with nuclear receptor pathways. Many structure–activity relationship models have been developed to predict chemical binding to the estrogen receptor as an indication of potential estrogenicity. Models based on either two-dimensional or three-dimensional molecular descriptions that have been used to predict potential for binding to the estrogen receptor are the subject of the current review. The utility of such approaches to predict binding potential of diverse chemical structures in …
Influence Of Suspended Solids On Acute Toxicity Of Carbofuran To Daphnia Magna: I. Interactive Effects, Steven P. Bradbury, Carl Herbrandson, Deborah L. Swackhamer
Influence Of Suspended Solids On Acute Toxicity Of Carbofuran To Daphnia Magna: I. Interactive Effects, Steven P. Bradbury, Carl Herbrandson, Deborah L. Swackhamer
Steven P. Bradbury
This study explored the effects on Daphnia magna from exposure to the pesticide carbofuran in combination with stress from suspended solids exposure. Our objective was to assess whether suspended solids affects the toxicodynamic response of D. magna to carbofuran. A series of laboratory experiments was performed where animals were exposed to carbofuran concentrations ranging from 0 to 160 mg/l in combination with suspended solids concentrations ranging from 0 to 10,000 mg/l. In the absence of suspended solids, effects of carbofuran were dose dependent and resulted in an EC(sub)50 of 92 mg/l. Exposure to suspended solids, up to extreme levels that …
Reactivity Profiles Of Ligands Of Mammalian Retinoic Acid Receptors: A Preliminary Corepa Analysis, Steven P. Bradbury, G. T. Ankley, O. G. Mekenyan, V. . Kamenska, P. K. Schmieder
Reactivity Profiles Of Ligands Of Mammalian Retinoic Acid Receptors: A Preliminary Corepa Analysis, Steven P. Bradbury, G. T. Ankley, O. G. Mekenyan, V. . Kamenska, P. K. Schmieder
Steven P. Bradbury
Retinoic acid and associated derivatives comprise a class of endogenous hormones that bind to and activate different families of retinoic acid receptors (RARs, RXRs), and control many aspects of vertebrate development. Identification of potential RAR and RXR ligands is of interest both from a pharmaceutical and toxicological perspective. The recently developed COREPA (COmmon REactivity PAttern) algorithm was used to establish reactivity profiles for a limited data set of retinoid receptor ligands in terms of activation of three RARs (a, b, g) and an RXR (a). Conformational analysis of a training set of retinoids and related analogues in terms of thermodynamic …
Narrowing Historical Uncertainty: Probabilistic Classification Of Ambiguously Identified Tree Species In Historical Forest Survey Data, David J. Mladenoff, Sally E. Dahir, Eric V. Nordheim, Lisa A. Schulte, Glenn G. Guntenspergen
Narrowing Historical Uncertainty: Probabilistic Classification Of Ambiguously Identified Tree Species In Historical Forest Survey Data, David J. Mladenoff, Sally E. Dahir, Eric V. Nordheim, Lisa A. Schulte, Glenn G. Guntenspergen
Lisa A. Schulte Moore
Historical data have increasingly become appreciated for insight into the past conditions of ecosystems. Uses of such data include assessing the extent of ecosystem change; deriving ecological baselines for management, restoration, and modeling; and assessing the importance of past conditions on the composition and function of current systems. One historical data set of this type is the Public Land Survey (PLS) of the United States General Land Office, which contains data on multiple tree species, sizes, and distances recorded at each survey point, located at half-mile (0.8-km) intervals on a 1-mi (1.6 km) grid. This survey method was begun in …
Phylogeographic Analysis Of The Threatened And Endangered Superconglutinate-Producing Mussels Of The Genus Lampsilis (Bivalvia: Unionidae), Kevin J. Roe, Charles Lydeard, Paul D. Hartfield
Phylogeographic Analysis Of The Threatened And Endangered Superconglutinate-Producing Mussels Of The Genus Lampsilis (Bivalvia: Unionidae), Kevin J. Roe, Charles Lydeard, Paul D. Hartfield
Kevin J. Roe
Several species of freshwater unionid mussels in the genus Lampsilis exhibit a remarkable reproductive strategy. Female mussels of these species enclose their larvae in a minnow-like lure, called a ‘superconglutinate’, to attract piscivorous fishes. When a fish attempts to ingest the superconglutinate the lure ruptures and the larvae are released to parasitize the fish. Of the four species of mussel which exhibit this strategy and are endemic to the Gulf Coast drainages of the southeastern United States, three are protected under the Endangered Species Act, and one is recognized as imperilled. Phylogenetic analysis of nucleotide sequences of the mitochondrial 16S …
A Buried Spruce Forest Provides Evidence At The Stand And Landscape Scale For The Effects Of Environment On Vegetation At The Pleistocene/Holocene Boundary, Douglas D. Stokke
A Buried Spruce Forest Provides Evidence At The Stand And Landscape Scale For The Effects Of Environment On Vegetation At The Pleistocene/Holocene Boundary, Douglas D. Stokke
Douglas D. Stokke
Due to a unique set of circumstances, we were able to excavate an entire spruce (Picea) forest in Michigan's Upper Peninsula, USA, which was buried in the early Holocene (9928 ± 133 uncalibrated 14C years bp). Trees ranged from < 5 cm to > 50 cm in diameter, and dominants were approximately 9 m tall. The stand was multi-aged, with a maximum tree age of 145 years. Well-preserved stem cross-sections (n = 140) were recovered and the entire stand was mapped. Stand reconstruction combined with pollen and sediment analysis revealed a pure spruce forest in the sandy lowlands surrounded by hills dominated by pine, oak …
A Computationally Based Identification Algorithm For Estrogen Receptor Ligands: Part 2. Evaluation Of A Herα Binding Affinity Model, Steven P. Bradbury, O. G. Mekenyan, V. Kamenska, P. K. Schmieder, G. T. Ankley
A Computationally Based Identification Algorithm For Estrogen Receptor Ligands: Part 2. Evaluation Of A Herα Binding Affinity Model, Steven P. Bradbury, O. G. Mekenyan, V. Kamenska, P. K. Schmieder, G. T. Ankley
Steven P. Bradbury
The objective of this study was to evaluate the capability of an expert system described in the previous paper (S. Bradbury et al., Toxicol. Sci. 58, 253–269) to identify the potential for chemicals to act as ligands of mammalian estrogen receptors (ERs). The basis of the expert system was a structure activity relationship (SAR) model, based on relative binding affinity (RBA) values for steroidal and nonsteroidal chemicals derived from human ERa (hERa) competitive binding assays. The expert system enables categorization of chemicals into (RBA ranges of < 0.1, 0.1 to 1, 1 to 10, 10 to 100, and >150% relative to 17b-estradiol. In the current analysis, the algorithm was evaluated with respect …
A Computationally Based Identification Algorithm For Estrogen Receptor Ligands: Part 1. Predicting Herα Binding Affinity, Steven P. Bradbury, V. Kamenska, P. Schmieder, G. Ankley, O. Mekenyan
A Computationally Based Identification Algorithm For Estrogen Receptor Ligands: Part 1. Predicting Herα Binding Affinity, Steven P. Bradbury, V. Kamenska, P. Schmieder, G. Ankley, O. Mekenyan
Steven P. Bradbury
The common reactivity pattern (COREPA) approach is a 3-dimensional, quantitative structure activity relationship (3-D QSAR) technique that permits identification and quantification of specific global and local stereoelectronic characteristics associated with a chemical’s biological activity. It goes beyond conventional 3-D QSAR approaches by incorporating dynamic chemical conformational flexibility in ligand-receptor interactions. The approach provides flexibility in screening chemical data sets in that it helps establish criteria for identifying false positives and false negatives, and is not dependent upon a predetermined and specified toxicophore or an alignment of conformers to a lead compound. The algorithm was recently used to screen chemical data …