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1999

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Articles 1 - 14 of 14

Full-Text Articles in Life Sciences

New Developments In A Hazard Identification Algorithm For Hormone Receptor Ligands, Steven P. Bradbury, Ovanes Mekenyan, Nina Nikolova, Stoyan Karabunarliev, Gerald T. Ankley, Bjorn Hansen Jun 1999

New Developments In A Hazard Identification Algorithm For Hormone Receptor Ligands, Steven P. Bradbury, Ovanes Mekenyan, Nina Nikolova, Stoyan Karabunarliev, Gerald T. Ankley, Bjorn Hansen

Steven P. Bradbury

Recently we described the Common REactivity PAttern (COREPA) technique to screen data sets of diverse structures for their ability to serve as ligands for steroid hormone receptors [1]. The approach identi®es and quanti®es similar global and local stereoelectronic characteristics associated with active ligands through a comparison of energeticallyreasonable conformer distributions for selected descriptors. For each stereoelectronic descriptor selected, discrete conformer distributions from a training set of ligands are evaluated and parameter ranges common for conformers from all the chemicals in the training set are identi®ed. The use of discrete partitions of parameter ranges to de®ne common ...


Recovery And Viability Of Edwardsiella Ictaluri From Great Blue Herons Ardea Herodias Fed E. Ictaluri-Infected Channel Catfish Lctalurus Punctatus Fingerlings, Paul R. Waterstrat, Brian S. Dorr, James F. Glahn, Mark E. Tobin Mar 1999

Recovery And Viability Of Edwardsiella Ictaluri From Great Blue Herons Ardea Herodias Fed E. Ictaluri-Infected Channel Catfish Lctalurus Punctatus Fingerlings, Paul R. Waterstrat, Brian S. Dorr, James F. Glahn, Mark E. Tobin

Brian S Dorr

No abstract provided.


Biotransformation Of 4-Methoxyphenol In Rainbow Trout (Oncorhynchus Mykiss) Hepatic Microsomes, Steven P. Bradbury, R. Kolanczyk, P. Schmieder, T. Spizzo Mar 1999

Biotransformation Of 4-Methoxyphenol In Rainbow Trout (Oncorhynchus Mykiss) Hepatic Microsomes, Steven P. Bradbury, R. Kolanczyk, P. Schmieder, T. Spizzo

Steven P. Bradbury

Rainbow trout liver microsomes were used to study the O-demethylation and ring hydroxylation of 4-methoxyphenol (4-MP) (4-hydroxyanisole) at 11 and 25°C by directly measuring the production of the primary metabolite hydroquinone (HQ), 4-methoxycatechol (4-MCAT), and additional metabolites. An HPLC method with integrated ultraviolet (UV) and electrochemical detection (ECD) was developed for metabolite identification and quantification at low concentrations. Sample handling with appropriate buffers, solvents, low temperature and light prevented loss of extremely labile metabolites. Saturation kinetics for the production of HQ via O-demethylation of 4-MP (0.66–40 mM) was never achieved, with substrate solubility being the limiting factor ...


Revegetating Desert Plant Communities, David A. Bainbridge Jan 1999

Revegetating Desert Plant Communities, David A. Bainbridge

David A Bainbridge

Desert revegetation is possible but not easy. Careful attention to plant production (root:shoot), site prep, planting, irrigation and aftercare can lead to good survival even under extreme desert conditions. Cost per survivor is a critical consideration.


Soil Pitting For Revegetation, David A. Bainbridge Jan 1999

Soil Pitting For Revegetation, David A. Bainbridge

David A Bainbridge

Soil pitting provides many benefits in ecological restoration of degraded lands. The pits capture rainwater, trap seeds and soil symbionts and protect seedlings from windblast.


Soil Treatment For Restoration Projects, David A. Bainbridge Jan 1999

Soil Treatment For Restoration Projects, David A. Bainbridge

David A Bainbridge

Soil treatment is a critical step in restoration projects. When soil problems are ignored restoration projects fail. Erosion, compaction, limited infiltration and other problems can make a site very different from its historic function and structure. Treatment can be done with equipment or by hand and will greatly improve chances for success.


Structural, Functional And Biochemical Responses Of Datura Innoxia Mill. To Coal-Smoke Pollution, Azamal Husen, Muhammad Iqbal Jan 1999

Structural, Functional And Biochemical Responses Of Datura Innoxia Mill. To Coal-Smoke Pollution, Azamal Husen, Muhammad Iqbal

Dr. Azamal Husen

Effect of coal-smoke pollution on Datura innoxia Mill. was investigated. D. innoxia has shown that leaf length, single leaf area, total leaf area and leaves per plant decreased but leaf biomass increased under pollution stress. Epidermal features of upper and lower leaf surface responded to pollution stress differently. Rate of photosynthesis and stomatal conductance were low, internal CO2 concentration was high and levels of chlorophyll a and b, total chlorophyll and carotenoids were reduced in polluted condition. Levels of proteins, reducing sugar in roots and sulphur contents in leaves, stem, roots and seeds showed significant increase under the polluted condition ...


A Comparison Of Three Methods For Determining Root-Knot Nematode Infection Of Cotton Roots, Robert G. Mcbride, Robert Mikkelsen Jan 1999

A Comparison Of Three Methods For Determining Root-Knot Nematode Infection Of Cotton Roots, Robert G. Mcbride, Robert Mikkelsen

Robert Mikkelsen

Three methods for determining the extent of infection of cotton roots (Gossypium hirsutum L.) by root-knot nematode, Meloidogyne incognita (Kofoid and White) Chitwood, were compared. Root-knot nematode eggs were added to pots containing either sterilized soil or soil amended with rye, and cotton seedlings were planted. Cotton root systems were then assessed for infection/damage after 14 and 28 days of exposure. At the 14-day sampling, the roots were stained, using the lactophenol acid fuchsin method and the juvenile nematodes counted. At the 28-day samplings, the cotton roots were given a visual rating for nematode-induced root galling (0-100), and the ...


Soil Amino Acid Utilization Among Species Of The Cyperaceae: Plant And Soil Processes, Ted K. Raab, David A. Lipson, Steven K. Scmidt, Russ K. Monson Jan 1999

Soil Amino Acid Utilization Among Species Of The Cyperaceae: Plant And Soil Processes, Ted K. Raab, David A. Lipson, Steven K. Scmidt, Russ K. Monson

Ted K. Raab

Amino acids are released during the decomposition of soil organic matter and have been shown to be utilized as a nitrogen source by some non-mycorrhizal species in the family Cyperaceae (the sedge family). Twelve out of 13 Cyperaceae species examined in the current study were capable of absorbing soil amino acids in the non-mycorrhizal state. With two exceptions (two species in the genus Kobresia), species from subalpine or alpine habitats exhibited lower rates of total nitrogen uptake compared to species from more temperate habitats, which is possibly explained by lower growth rates in the alpine and subalpine species and a ...


Variation In Competitive Abilities Of Plants And Microbes For Specific Amino Acids, David A. Lipson, Ted K. Raab, Steven K. Schmidt, Russ K. Monson Jan 1999

Variation In Competitive Abilities Of Plants And Microbes For Specific Amino Acids, David A. Lipson, Ted K. Raab, Steven K. Schmidt, Russ K. Monson

Ted K. Raab

Microbes are assumed to possess strong competitive advantages over plants for uptake of nutrients from the soil. The finding that non-mycorrhizal plants can obtain a significant fraction of their N requirement from soil amino acids contradicts this assumption. The amino acid glycine (Gly) has been used as a model amino acid in many recent studies. Our preliminary studies showed that Gly was a poor substrate for microbial growth compared to other amino acids. We tested the hypothesis that the alpine sedge Kobresia myosuroides competes better for Gly than for other amino acids because of decreased microbial demand for this compound ...


New Testing Apparatus For Assessing Interactive Effects Of Suspended Solids And Chemical Stressors On Plankton Invertebrates, Steven P. Bradbury, Carl Herbrandson, Deborah L. Swackhamer Jan 1999

New Testing Apparatus For Assessing Interactive Effects Of Suspended Solids And Chemical Stressors On Plankton Invertebrates, Steven P. Bradbury, Carl Herbrandson, Deborah L. Swackhamer

Steven P. Bradbury

To better predict and interpret the responses of aquatic organisms to environmentally relevant chemical exposures, it is necessary to investigate the combined effects of physical (e.g., suspended solids) and chemical stressors. One of the limitations in investigating suspended solids–chemical interactions has been the lack of an appropriate testing system. The specific objective of the current study was to develop and assess a suspended solids testing apparatus (SSTA) for studies on the combined effects of suspended solids and chemicals on aquatic invertebrates. The SSTA was designed to permit the assessment of varying suspended solids concentrations on Daphnia magna at ...


The Effect Of Water Level Management On The Soils And Vegetation Of Two Coastal Louisiana Marshes, Brian J. Wilsey, K. M. Flynn, I. A. Mendelssohn Jan 1999

The Effect Of Water Level Management On The Soils And Vegetation Of Two Coastal Louisiana Marshes, Brian J. Wilsey, K. M. Flynn, I. A. Mendelssohn

Brian J. Wilsey

Wetland degradation and loss is the result of a combination of natural causes and anthropogenic activities and is a serious problem in coastal Louisiana, where approximately 80% of the total US coastal wetland loss since the 1930’s has occurred. One method currently used to address this wetland loss problem is structural marsh management,which is the use of levees and water control structures to control hydroperiod. The effects of structural marsh management on two managed marshes in Southern Louisiana (Unit 4 of the Rockefeller Wildlife Refuge and the Fina LaTerre Mitigation Bank) were evaluated by comparing the soils and ...


Temporal Changes In Purity And Specific Activity Of Tritium-Labeled 2,3,7,8-Tetrachlorodibenzo-Ρ-Dioxin: Radiopurity Model For Toxicology, Steven P. Bradbury, Joseph D. Fernandez, Philip M. Cook, Brian C. Butterworth Jan 1999

Temporal Changes In Purity And Specific Activity Of Tritium-Labeled 2,3,7,8-Tetrachlorodibenzo-Ρ-Dioxin: Radiopurity Model For Toxicology, Steven P. Bradbury, Joseph D. Fernandez, Philip M. Cook, Brian C. Butterworth

Steven P. Bradbury

The specific activity (S) and radiopurity (R) of tritium labeled 2,3,7,8-tetrachlorodibenzo-p-dioxin, [3H]TCDD, were measured by gas chromatography/mass spectrometry (GC/ MS) while attempting to accurately characterize TCDD doses received by invertebrates, fish, and fish embryos during several toxicology studies conducted over a 3 year period. The [3H]TCDD sample was found to consist of six TCDD analogues involving hydrogen, deuterium, and tritium substitution at the 1,6-dibenzo-p-dioxin carbon positions and a complex mixture of impurities (with and without tritium labels). Planar aromatic impurities were identified as tolyl- TCDD adducts and appeared to result from the decay ...


Derivation Of Wildlife Values For Mercury, Steven P. Bradbury, John Nichols, Jeff Swartout Jan 1999

Derivation Of Wildlife Values For Mercury, Steven P. Bradbury, John Nichols, Jeff Swartout

Steven P. Bradbury

A procedure has been developed to estimate surface water concentrations of toxicants (“wildlife values”) that will protect the viability of wildlife populations associated with aquatic resources. This procedure was designed primarily to protect piscivorous birds and mammals from compounds that bioaccumulate in fish and was used in the Great Lakes Water Quality Initiative (GLI) to calculate wildlife values (WV) for mercury, DDT/DDE, total polychlorinated biphenyls (PCBs), and 2,3,7,8-tetrachlorodibenzodioxin (TCDD). Published in 1995, and expressed as total mercury in unfiltered water, the final wildlife value (WVf) for mercury derived in the GLI was 1300 pg Hg/L ...