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At least 649 records · Page 36Linked to original sources
USGS2021

Sex- and developmental stage-related differences in the hepatic transcriptome of Japanese quail (Coturnix japonica) exposed to 17β-Trenbolone

Endocrine-disrupting chemicals can cause transcriptomic changes that may disrupt biological processes associated with reproductive function including metabolism, transport, and cell growth. We investigated effects from in ovo and dietary exposure to 17β-trenbolone (at 0, 1, and 10 ppm) on the Japanese quail ( Coturnix japonica ) hepatic transcriptome. Our objectives were to identify differentially expressed hepatic genes, assess perturbations of biological pathways, and examine sex- and developmental stage–related differences. The number of significantly differentially expressed genes was higher in embryos than in adults. Male embryos exhibited greater differential gene expression than female embryos, whereas in adults, males and females exhibited similar numbers of differentially expressed genes (>2-fold). Vitellogenin and apovitellenin-1 were up-regulated in male adults exposed to 10 ppm 17β-trenbolone, and these birds also exhibited indications of immunomodulation. Functional grouping of differentially expressed genes identified processes including metabolism and transport of biomolecules, enzyme activity, and extracellular matrix interactions. Pathway enrichment analyses identified as perturbed peroxisome proliferator–activated receptor pathway, cardiac muscle contraction, gluconeogenesis, growth factor signaling, focal adhesion, and bile acid biosynthesis. One of the primary uses of 17β-trenbolone is that of a growth promoter, and these results identify effects on mechanistic pathways related to steroidogenesis, cell proliferation, differentiation, growth, and metabolism of lipids and proteins.

Environmental Toxicology and Chemistry↗
USGS1986

Adaptation of Selenastrum capricornutum (Chlorophyceae) to copper

Selenastrum capricornutum Printz, growing in a chemically defined medium, was used as a model for studying adaptation of algae to a toxic metal (copper) ion. Cells exhibited lag‐phase adaptation to 0.8 μM total Cu (10 −12 M free ion concentration) after 20 generations of Cu exposure. Selenastrum adapted to the same concentration when Cu was gradually introduced over an 8‐h period using a specially designed apparatus that provided a transient increase in exposure concentration. Cu adaptation was not attributable to media conditioning by algal exudates. Duration of lag phase was a more sensitive index of copper toxicity to Selenastrum that was growth rate or stationary‐phase cell density under the experimental conditions used. Chemical speciation of the Cu dosing solution influenced the duration of lag phase even when media formulations were identical after dosing. Selenastrum initially exposed to Cu in a CuCl 2 injection solution exhibited a lag phase of 3.9 d, but this was reduced to 1.5 d when a CuEDTA solution was used to achieve the same total Cu and EDTA concentrations. Physical and chemical processes that accelerated the rate of increase in cupric ion concentration generally increased the duration of lag phase.

Environmental Toxicology and Chemistry↗
USGS2006

Flow cytometry, morphometry and histopathology as biomarkers of benzo[a]pyrene exposure in brown bullheads (ameiurus nebulosus)

Brown bullheads were given a single intraperitoneal dose of 0, 5, 25 or 125 mg kg −1 benzo[ a ]pyrene (BaP), a carcinogenic polycyclic aromatic hydrocarbon, and evaluated over 18 months. Flow cytometric analyses of hepatocyte DNA content indicated an increase in DNA synthesis in BaP-exposed fish prior to day 14 post-exposure. Thereafter, all flow cytometric variables returned to initial levels. Histopathological evaluation of livers from fish sampled at 18 months revealed significant differences among treatments in the amount of hepatic macrophage ceroid pigmentation and basophilic staining intensity. No neoplasms or changes in blood cell DNA content were detected. Significant morphometric variations existed among fish, but differences between sexes overshadowed differences attributable to dose. Flow cytometry yielded no evidence of long-term DNA alterations from a single exposure to BaP; however, the differences detected by DNA analysis shortly after the toxic event suggest that flow cytometric cell cycle analysis may be useful for documenting continuing exposures.

Journal of Applied Toxicology↗
USGS2013

Hydrodynamics of spur and groove formations on a coral reef

Spur and groove (SAG) formations are found on the fore reefs of many coral reefs worldwide. Although these formations are primarily present in wave‐dominated environments, their effect on wave‐driven hydrodynamics is not well understood. A two‐dimensional, depth‐averaged, phase‐resolving nonlinear Boussinesq model ( funwaveC ) was used to model hydrodynamics on a simplified SAG system. The modeling results show that the SAG formations together with shoaling waves induce a nearshore Lagrangian circulation pattern of counter‐rotating circulation cells. The mechanism driving the modeled flow is an alongshore imbalance between the pressure gradient (PG) and nonlinear wave (NLW) terms in the momentum balance. Variations in model parameters suggest the strongest factors affecting circulation include spur‐normal waves, increased wave height, weak alongshore currents, increased spur height, and decreased bottom drag. The modeled circulation is consistent with a simple scaling analysis based on the dynamical balance of NLW, PG, and bottom stress terms. Model results indicate that the SAG formations efficiently drive circulation cells when the alongshore SAG wavelength allows for the effects of diffraction to create alongshore differences in wave height without changing the mean wave angle.

Journal of Geophysical Research C: Oceans↗
USGS2006

Use of the gamma distribution to represent monthly rainfall in Africa for drought monitoring applications

Evaluating a range of scenarios that accurately reflect precipitation variability is critical for water resource applications. Inputs to these applications can be provided using location- and interval-specific probability distributions. These distributions make it possible to estimate the likelihood of rainfall being within a specified range. In this paper, we demonstrate the feasibility of fitting cell-by-cell probability distributions to grids of monthly interpolated, continent-wide data. Future work will then detail applications of these grids to improved satellite-remote sensing of drought and interpretations of probabilistic climate outlook forum forecasts. The gamma distribution is well suited to these applications because it is fairly familiar to African scientists, and capable of representing a variety of distribution shapes. This study tests the goodness-of-fit using the Kolmogorov–Smirnov (KS) test, and compares these results against another distribution commonly used in rainfall events, the Weibull. The gamma distribution is suitable for roughly 98% of the locations over all months. The techniques and results presented in this study provide a foundation for use of the gamma distribution to generate drivers for various rain-related models. These models are used as decision support tools for the management of water and agricultural resources as well as food reserves by providing decision makers with ways to evaluate the likelihood of various rainfall accumulations and assess different scenarios in Africa.

International Journal of Climatology↗
USGS2008

Physiographically sensitive mapping of climatological temperature and precipitation across the conterminous United States

Spatial climate data sets of 1971–2000 mean monthly precipitation and minimum and maximum temperature were developed for the conterminous United States. These 30‐arcsec (∼800‐m) grids are the official spatial climate data sets of the U.S. Department of Agriculture. The PRISM (Parameter‐elevation Relationships on Independent Slopes Model) interpolation method was used to develop data sets that reflected, as closely as possible, the current state of knowledge of spatial climate patterns in the United States. PRISM calculates a climate–elevation regression for each digital elevation model (DEM) grid cell, and stations entering the regression are assigned weights based primarily on the physiographic similarity of the station to the grid cell. Factors considered are location, elevation, coastal proximity, topographic facet orientation, vertical atmospheric layer, topographic position, and orographic effectiveness of the terrain. Surface stations used in the analysis numbered nearly 13 000 for precipitation and 10 000 for temperature. Station data were spatially quality controlled, and short‐period‐of‐record averages adjusted to better reflect the 1971–2000 period. PRISM interpolation uncertainties were estimated with cross‐validation (C‐V) mean absolute error (MAE) and the 70% prediction interval of the climate–elevation regression function. The two measures were not well correlated at the point level, but were similar when averaged over large regions. The PRISM data set was compared with the WorldClim and Daymet spatial climate data sets. The comparison demonstrated that using a relatively dense station data set and the physiographically sensitive PRISM interpolation process resulted in substantially improved climate grids over those of WorldClim and Daymet. The improvement varied, however, depending on the complexity of the region. Mountainous and coastal areas of the western United States, characterized by sparse data coverage, large elevation gradients, rain shadows, inversions, cold air drainage, and coastal effects, showed the greatest improvement. The PRISM data set benefited from a peer review procedure that incorporated local knowledge and data into the development process.

International Journal of Climatology↗
USGS2018

Looking beyond wildlife: Using remote cameras to evaluate accuracy of gridded snow data

The use of remote cameras is widespread in wildlife ecology, yet few examples exist of their utility for collecting environmental data. We used a novel camera trap method to evaluate the accuracy of gridded snow data in a mountainous region of the northeastern US. We were specifically interested in assessing (1) how snow depth observations from remote cameras compare with gridded climate data, (2) the sources of error associated with the gridded data and (3) the influence of spatial sampling on bias. We compared daily observations recorded by remote cameras with Snow Data Assimilation System (SNODAS ) gridded predictions using data from three winters (2014–2016). Snow depth observations were correlated with SNODAS predictions for sites ( R 2 = 0.20) and regions ( R 2 = 0.16), yet we detected factors associated with SNODAS bias at both scales. Specifically, SNODAS underpredicted depths at high elevations, at sites with higher solar radiation, and within conifer‐dominated forest. Depths were most underpredicted at highest elevations, up to 44 and 26 cm on average at the site and region scales, respectively. Bias was greatest when predictions were lowest, occasionally predicting snow absence when depths were >100 cm at camera sites. We also detected breakdowns in accuracy when certain environmental conditions varied within the 1 km 2 SNODAS grid cells. For example, underprediction was greatest when the solar radiation values of camera stations increased relative to the mean of the SNODAS grid cells. This relationship was most prominent in mountainous regions, suggesting that factors which influence solar radiation (e.g. topographic complexity) contribute to SNODAS inaccuracy. We caution using gridded snow data for ecological studies when bias is unknown. We suggest increased sampling to adjust for errors associated with gridded data products that arise from factors, such as forest cover and topographic variability. Increasing resolution and accuracy of climate data will improve predictions of species’ responses to climate change.

New Hampshire, Vermont↗
USGS1989

Preliminary characterization of a virus causing infectious anemia among stocks of salmonid fish in the western United States

Since 1982, anemias occurring in stocks of yearling coho ( Oncorhynchus kisutch ) and chinook salmon (Oncorhynchus tshawytscha ) have been associated with serious losses at hatcheries in the Pacific Northwest, USA. The anemia is often accompanied by infections with external fungus (e.g. Saprolegnia) or the bacterial pathogens Cytophaga psychrophila or Renibacterium salmoninarum (Holt and Rohovec 1984, Leek 1987). The losses associated with the anemia are thought to be caused by these secondary infections. Blood smears that were made from anemic fish and stained with Giemsa or pinacyanol chloride showed erythrocytic inclusions ranging in size from 1 to 8 um and varying in number per cell. Thin sections of infected red blood cells (RBC) examined by electron microscopy revealed virus particles approximately 70 nm in diameter. The virions were scattered in the cytoplasm of the RBC or contained within membrane bound organelles. These virus particles were morphologically distinct from the iridovirus, erythrocytic necrosis virus (ENV), which is also associated with anemia (Holt and Rohovec 1984, Leek 1987). Evidence suggests that the etiological agent of this new anemic disease, termed erythrocytic inclusion body syndrome (EIBS) by Leek (1987), is a previously undescribed virus infecting salmon. The purpose of this study was to experimentally transmit the disease to healthy fish, to determine the blood parameters associated with infection, and to investigate the nature of the virus associated with EIBS.

Book chapter↗
USGS1994

Physiology of seawater acclimation in the striped bass, Morone saxatilis (Walbaum)

Several experiments were performed to investigate the physiology of seawater acclimation in the striped bass, Morone saxatilis . Transfer of fish from fresh water (FW) to seawater (SW; 31–32 ppt) induced only a minimal disturbance of osmotic homeostasis. Ambient salinity did not affect plasma thyroxine, but plasma cortisol remained elevated for 24h after SW transfer. Gill and opercular membrane chloride cell density and Na + ,K + -ATPase activity were relatively high and unaffected by salinity. Average chloride cell size, however, was slightly increased (16%) in SW-acclimated fish. Gill succinate dehydrogenase activity was higher in SW-acclimated fish than in FW fish. Kidney Na + , K + -ATPase activity was slightly lower (16%) in SW fish than in FW fish. Posterior intestinal Na + ,K + -ATPase activity and water transport capacity (J v ) did not change upon SW transfer, whereas middle intestinal Na + ,K + -ATPase activity increased 35% after transfer and was correlated with an increase in J v (110%). As salinity induced only minor changes in the osmoregulatory organs examined, it is proposed that the intrinsic euryhalinity of the striped bass may be related to a high degree of “preparedness” for hypoosmoregulation that is uncommon among teleosts studied to data.

Fish Physiology and Biochemistry↗
USGS1985

Isolation of anaerobic oxalate-degrading bacteria from freshwater lake sediments

Enrichment cultures that anaerobically degraded oxalate were obtained from lake sediment inocula. From these, 5 pure cultures of anaerobic oxalate-degrading bacteria were isolated and partially characterized. The isolates were Gram-negative, non-sporeforming, non-motile, obligate anaerobes. Oxalate was required for growth and was stoichiometrically converted to formate; 14 CO 2 was also recovered when 14 C-oxalate was added. Maximal growth occurred when the oxalate concentration was 50 mM. Acetate stimulated growth in the presence of oxalate, however, 14 C-experiments indicated that acetate was only utilized for cell carbon. The isolates were either spiral-shaped or rod-shaped organisms. The first morphotype grew much more slowly than the second and exhibited 13-fold lower cell yields. These isolates represent a new strain of oxalate-degrading bacteria. The second morphotype was similar to the anaerobic oxalate-degrading bacteria previously found in rumen. This report extends the known habitats in which anaerobic oxalate-degrading organisms have been found to include aquatic sediments.

Archives of Microbiology↗
USGS2013

Determination of water retention in stratified porous materials

Predicted and measured water-retention values, θ ( ψ ), were compared for repacked, stratified core samples consisting of either a sand with a stone-bearing layer or a sand with a clay loam layer in various spatial orientations. Stratified core samples were packed in submersible pressure outflow cells, then water-retention measurements were performed between matric potentials, ψ , of 0 to -100 kPa. Predictions of θ ( ψ ) were based on a simple volume-averaging model using estimates of the relative fraction and θ ( ψ ) values of each textural component within a stratified sample. In general, predicted θ ( ψ ) curves resembled measured curves well, except at higher saturations in a sample consisting of a clay loam layer over a sand layer. In this case, the model averaged the air-entry of both materials, while the air-entry of the sample was controlled by the clay loam in contact with the cell's air-pressure inlet. In situ, avenues for air-entry generally exist around clay layers, so that the model should adequately predict air-entry for stratified formations regardless of spatial orientation of fine versus coarse layers. Agreement between measured and predicted volumetric water contents, θ , was variable though encouraging, with mean differences between measured and predicted θ values in the range of 10%. Differences in θ of this magnitude are expected due to variability in pore structure between samples, and do not indicate inherent problems with the volume averaging model. This suggets that explicit modeling of stratified formations through detailed characterization of the stratigraphy has the potential of yielding accurate θ ( ψ ) values. However, hydraulic-equilibration times were distinctly different for each variation in spatial orientation of textural layering, indicating that transient behavior during drainage in stratified formations is highly sensitive to the stratigraphic sequence of textural components, as well as the volume fraction of each textural component in a formation. This indicates that prolonged residence times of water, nutrients, and pollutants are likely within finer-textured layers, when ψ conditions have resulted in drainage of underlying coarser-textured strata.

Transport in Porous Media↗
USGS1972

Fish rhabdoviruses: Morphology and ultrastructure of North American salmonid isolates

The morphology and ultrastructure of three North American salmonid pathogens, Oregon sockeye salmon, chinook salmon and infectious hematopoietic necrosis viruses, were examined by thin sectioning and negative staining after growth in fathead minnow cells at 10 ° C. The viruses matured at the plasma membrane of these cells. They were approximately 170 nm in length, 70 nm in width and had internal striations with a periodicity of 5.5nm. They were rounded on one end and planar on the other ( i.e. , bullet shaped). By morphological criteria, these viruses are rhabdoviruses with dimensions and ultrastructural features similar to vesicular stomatitis virus.

Archiv Fur Die Gesamte Virusforschung↗
USGS2010

Seismic hazard and risk assessments for Beijing-Tianjin-Tangshan, China, area

Seismic hazard and risk in the Beijing–Tianjin–Tangshan, China, area were estimated from 500-year intensity observations. First, we digitized the intensity observations (maps) using ArcGIS with a cell size of 0.1 × 0.1°. Second, we performed a statistical analysis on the digitized intensity data, determined an average b value (0.39), and derived the intensity–frequency relationship (hazard curve) for each cell. Finally, based on a Poisson model for earthquake occurrence, we calculated seismic risk in terms of a probability of I ≥ 7, 8, or 9 in 50 years. We also calculated the corresponding 10 percent probability of exceedance of these intensities in 50 years. The advantages of assessing seismic hazard and risk from intensity records are that (1) fewer assumptions (i.e., earthquake source and ground motion attenuation) are made, and (2) site-effect is included. Our study shows that the area has high seismic hazard and risk. Our study also suggests that current design peak ground acceleration or intensity for the area may not be adequate.

North China Plain↗
USGS2016

Zinc and lead poisoning in wild birds in the Tri-State Mining District (Oklahoma, Kansas, Missouri)

contaminated with Pb, Cd, and Zn from mining, milling and smelting. Metals have been dispersed heterogeneously throughout the District in the form of milled mine waste ('chat'), as flotation tailings and from smelters as aerial deposition or slag. This study was conducted to determine if the habitat has been contaminated to the extent that the assessment populations of wild birds are exposed to toxic concentrations of metals. American robins (Turdus migratorius), northern cardinals (Cardinalis cardinalis), and waterfowl had increased Pb tissue concentrations (p < 0.05) compared with Pb tissue concentrations from reference birds, and the exposure of songbirds to Pb was comparable with that of birds observed at other sites severely contaminated with Pb. Mean activities of the Pb-sensitive enzyme delta-aminolevulinic acid dehydratase (ALAD) were decreased by >50% in red blood cells in these birds (p < 0.05). Several birds had tissue concentrations of Pb that have been associated with impaired biological functions and external signs of poisoning. Cadmium was increased in kidneys of songbirds (p < 0.05), but no proximal tubule cell necrosis associated with Cd poisoning was observed. Zinc concentrations in liver and kidney of waterfowl were significantly higher (p < 0.05) than reference values. The increased environmental concentrations of Zn associated with mining in the District accounted for the pancreatitis previously observed in five waterfowl from the District. The District is the first site at which free-flying wild birds have been found to be suffering severe effects of Zn poisoning.

Kansas, Missouri, Oklahoma↗
USGS2007

Effect of in ovo exposure to an organochlorine mixture extracted from double crested cormorant eggs (Phalacrocorax auritus) and PCB 126 on immune function of juvenile chickens

Organochlorine (OC) contaminants including polychlorinated biphenyls (PCBs) and p, p'-dichlorodiphenyldichloroethylene (DDE) have been associated with immune modulation in wild fish-eating birds from the Great Lakes. The objective of this study was to evaluate the immune function of juvenile chickens after in ovo exposure to PCB 126 or an environmentally relevant OC mixture extracted from eggs of double crested cormorants (Phalacrocorax auritus) from Green Bay, Lake Michigan, USA. Fertile white leghorn chicken (Gallus domesticus) eggs were injected before incubation with 0.55-1.79 ng TCDD equivalents (TEQ)/egg PCB 126 and 1.2-4.9 ng TEQs/egg of cormorant egg extract into the air cell in two separate experiments. After hatching, the immune function was tested using in vivo phytohemagglutinin (PHA) skin response in 11-day-old chicks, antibody titers to immunization with sheep red blood cells (SRBC) in 28-day-old chicks, and, at necropsy, thymus and bursal mass and cellularity. PCB 126 decreased antibody titers at all doses and decreased the thymus and bursa index but not cellularity at 1.79 ng TEQ/egg. The cormorant egg extract caused no significant alterations in immune function even though it has been demonstrated as immunotoxic in chicken embryos. However, twofold to threefold increases in total anti-SRBC titers in 28-day-old chicks exposed to 1.2 or 2.4 ng TEQ/egg of cormorant extract were similar to elevations in anti-SRBC titer observed in Caspian tern (Sterna caspia) chicks from a highly OC-contaminated site in Saginaw Bay, Lake Huron. Posthatch exposure to OC through fish consumption in addition to in ovo OC exposure might be associated with the immune modulation reported in wild birds. Chicks in this study might have begun to compensate for embryonic immunotoxicity by the ages at which we studied them. ?? 2007 Springer Science+Business Media, LLC.

Archives of Environmental Contamination and Toxico↗
USGS2008

Bacterial succession within an ephemeral hypereutrophic mojave desert playa lake

Ephemerally wet playas are conspicuous features of arid landscapes worldwide; however, they have not been well studied as habitats for microorganisms. We tracked the geochemistry and microbial community in Silver Lake playa, California, over one flooding/desiccation cycle following the unusually wet winter of 2004-2005. Over the course of the study, total dissolved solids increased by 10-fold and pH increased by nearly one unit. As the lake contracted and temperatures increased over the summer, a moderately dense planktonic population of 1 ?????106 cells ml-1 of culturable heterotrophs was replaced by a dense population of more than 1????????109 cells ml-1, which appears to be the highest concentration of culturable planktonic heterotrophs reported in any natural aquatic ecosystem. This correlated with a dramatic depletion of nitrate as well as changes in the microbial community, as assessed by small subunit ribosomal RNA gene sequencing of bacterial isolates and uncultivated clones. Isolates from the early-phase flooded playa were primarily Actinobacteria, Firmicutes, and Bacteroidetes, yet clone libraries were dominated by Betaproteobacteria and yet uncultivated Actinobacteria. Isolates from the late-flooded phase ecosystem were predominantly Proteobacteria, particularly alkalitolerant isolates of Rhodobaca, Porphyrobacter, Hydrogenophaga, Alishwenella, and relatives of Thauera; however, clone libraries were composed almost entirely of Synechococcus (Cyanobacteria). A sample taken after the playa surface was completely desiccated contained diverse culturable Actinobacteria typically isolated from soils. In total, 205 isolates and 166 clones represented 82 and 44 species-level groups, respectively, including a wide diversity of Proteobacteria, Bacteroidetes, Actinobacteria, Firmicutes, Gemmatimonadetes, Acidobacteria, and Cyanobacteria. ?? 2008 Springer Science+Business Media, LLC.

Microbial Ecology↗
USGS2005

Characterizing lesions in corals from American Samoa

The study of coral disease has suffered from an absence of systematic approaches that are commonly used to determine causes of diseases in animals. There is a critical need to develop a standardized and portable nomenclature for coral lesions in the field and to incorporate more commonly available biomedical tools in coral disease surveys to determine the potential causes of lesions in corals. We characterized lesions in corals from American Samoa based on gross and microscopic morphology and classified them as discoloration, growth anomalies, or tissue loss. The most common microscopic finding in corals manifesting discoloration was the depletion of zooxanthellae, followed by necrosis, sometimes associated with invasive algae or fungi. The most common microscopic lesion in corals manifesting tissue loss was cell necrosis often associated with algae, fungi, or protozoa. Corals with growth anomaly had microscopic evidence of hyperplasia of gastrovascular canals, followed by necrosis associated with algae or metazoa (polychaete worms). Several species of apparently normal corals also had microscopic changes, including the presence of bacterial aggregates or crustacea in tissues. A single type of gross lesion (e.g., discoloration) could have different microscopic manifestations. This phenomenon underlines the importance of using microscopy to provide a more systematic description of coral lesions and to detect potential pathogens associated with these lesions.

Coral Reefs↗