bluuebunny/crossref_metadata_2025 huggingface dataset:
Wildfire Effects on Soil Nutrients and Leaching in a Tahoe Basin Watershed
Authors: Murphy J. D. , Johnson D. W. , Miller W. W. , Walker R. F. , Carroll E. F. , Blank R. R.
Published: February 2006

A wildfire burned through a previously sampled research site, allowing pre‐ and post‐burn measurements of the forest floor, soils, and soil leaching near Lake Tahoe, Nevada. Fire and post‐fire erosion caused large and statistically significant (P ≤ 0.05) losses of C, N, P, S, Ca, and Mg from the forest floor. There were no statistically significant effects on mineral soils aside from a decrease in total N in the surface (A11) horizon, an increase in pH in the A11 horizon, and increases in water‐extractable SO42− in the A11 and A12 horizons. Burning caused consistent but nonsignificant increases in exchangeable Ca2+ in most horizons, but no consistent or statistically significant effects on exchangeable K+ or Mg2+, or on Bray‐, bicarbonate‐, or water‐extractable P concentrations. Before the burn, there were no significant differences in leaching, but during the first winter after the fire, soil solution concentrations of NH4+, NO3−, ortho‐P, and (especially) SO42− were elevated in the burned area, and resin lysimeters showed significant increases in the leaching of NH4+ and mineral N. The leaching losses of mineral N were much smaller than the losses from the forest floor and A11 horizons, however. We conclude that the major short‐term effects of wildfire were on leaching whereas the major long‐term effect was the loss of N from the forest floor and soil during the fire.
Bedding and Within‐Pen Location Effects on Feedlot Pen Runoff Quality Using a Rainfall Simulator
Authors: Miller Jim J. , Olson Edith C. S. , Chanasyk David S. , Beasley Bruce W. , Yanke L. Jay , Larney Francis J. , McAllister Tim A. , Olson Barry M. , Selinger L. Brent
Published: February 2006

Soluble salts, nutrients, and pathogenic bacteria in feedlot‐pen runoff have the potential to cause pollution of the environment. A 2‐yr study (1998–1999) was conducted at a beef cattle (Bos taurus) feedlot in southern Alberta, Canada, to determine the effect of bedding material [barley (Hordeum vulgare L.) straw versus wood chips] and within‐pen location on the chemical and bacterial properties of pen‐floor runoff. Runoff was generated with a portable rainfall simulator and analyzed for chemical content (nitrogen [N], phosphorus [P], soluble salts, electrical conductivity [EC], sodium adsorption ratio [SAR], dissolved oxygen [DO], and pH) and populations of three groups of bacteria (Escherichia coli, total coliforms, total aerobic heterotrophs at 27°C) in 1998 and 1999. Bedding had a significant (P ≤ 0.05) effect on NH4–N concentration and load in 1999, SO4 load in 1998, SO4 concentration and load in 1999, and total coliforms in both years; where these three variables were higher in wood than straw pens. Location had a significant effect on EC and concentrations of total Kjeldahl nitrogen (TKN), Na, K, SO4, and Cl in 1998, and total coliforms in both years. These seven variables were higher at the bedding pack than pen floor location, indicating that bedding packs were major reservoirs of TKN, soluble salts, and total coliforms. Significantly higher dissolved reactive phosphorus (DRP), total P, and NH4–N concentrations and loads at the bedding pack location in wood pens in 1998, and a similar trend for TKN concentration in 1999, indicated that this bedding–location treatment was a greater source of nutrients to runoff than the other three bedding–location treatments. Bedding, location, and their interaction may therefore be a potential tool to manage nutrients, soluble salts, and bacteria in feedlot runoff.
Spontaneous Hybridization between Bread Wheat (Triticum aestivum L.) and Its Wild Relatives in Europe
Authors: Zaharieva M. , Monneveux P.
Published: February 2006

In Europe, wild wheat relatives of the Triticum–Aegilops complex grow in sympatry with cultivated bread wheat (Triticum aestivum L.) and spontaneous hybridization is known to occur. With the development of transgenic wheat, an understanding of the likelihood and occurrence of hybridization and introgression between wheat and its relatives is needed for use in risk assessment. To assess the probability of wheat to wild relative gene introgression, the distribution and biology of wheat wild relatives and their genome affinity and crossability with bread wheat were reviewed. Twelve of the 22 known Aegilops species, as well as one wild Triticum species, T. monococcum L. subsp. aegilopoides (Link) Thell., are known to occur in Europe near or within wheat cultivation. Five tetraploid species, Ae. cylindrica Host., Ae. triuncialis L., Ae. geniculata Roth., Ae. neglecta Req. ex Berthol., and Ae. biuncialis Vis., have wide distribution in most European countries. Bread wheat, wild Aegilops species, and Triticum species are predominantly autogamous (except Ae. speltoides Tausch, typically allogamous), but outcrossing among species is possible depending on species sympatry, concurrent flowering, and sexual compatibility. Spontaneous hybridization with wheat was reported for most of the tetraploid Aegilops species. The probability of gene transfer and gene retention in hybrid progenies is, however, higher when a gene is located on a shared genome, particularly on the D genome shared with Ae. cylindrica and Ae. ventricosa Tausch. Case‐by‐case and region‐by‐region assessments are needed to evaluate the risk associated with production and competitiveness of hybrids and their progeny.
Chromosomal Location of the Russian Wheat Aphid Resistance Gene, Dn5
Authors: Heyns Ian , Groenewald Ewald , Marais Francois , du Toit Francois , Tolmay Vicky
Published: February 2006

Recent reports suggested that the Russian wheat aphid (Diuraphis noxia Mordvilko, RWA) resistance gene Dn5 is located on wheat (Triticum aestivum L.) chromosome arm 7DS rather than on 7DL. A further attempt was therefore made to physically map the gene employing the same source material previously used to describe, name, and map it. It was possible to derive monotelosomic 7DL plants carrying Dn5 on the telosome. Such plants could not be developed for the short arm. The identities of the 7DS and 7DL telosomes were confirmed using mapped microsatellite a‐nd endopeptidase markers and showed unequivocally that Dn5 occurs on 7DL. It appears that use of the wrong Dn5 source material could explain some of the inconsistencies in earlier genetic studies involving this gene. In an attempt to also genetically map Dn5, a doubled haploid (DH) mapping population was derived from the cross PI 294994 × ‘Chinese Spring’ (CS). A single RWA resistance gene, believed to be Dn5, segregated in the population and was mapped together with 12 microsatellite loci and the Ep‐D1 locus. The Dn gene mapped near the centromere on 7DS. However, closer inspection of the data suggested that segregation distortion with opposite effect occurred within two areas of the region that was being mapped. The combined distortion effect rendered the data unreliable and it was not possible to unambiguously determine the chromosome arm on which the Dn gene resides. It appeared that the chromosome 7D proximal regions may be problematic in terms of genetic analysis based on segregation data.
Use of aroA‐M1 as a Selectable Marker for Brassica napus Transformation
Authors: Wang J. X. , Zhao F. Y. , Xu P.
Published: February 2006

The aroA‐M1 mutant consisting of an N‐terminal portion of Escherichia coli 5‐enolpyruvylshkimate‐3‐phosphate synthase (EPSPS) and a C‐terminal portion of Salmonella typhimurium EPSPS confers high resistance to glyphosate because of a decrease in the Km(PEP) and an increase in the Ki(glyphosate). In this paper, we constructed a binary vector carrying the aroA‐M1 mutant gene under the control of the CaMV 35S promoter for Agrobacterium‐mediated gene transfer to Brassica napus L. Transgenic Brassica plants with increased resistance to glyphosate were obtained by cocultivation of hypocotyl explants with Agrobacterium tumefaciens and direct selection on media containing glyphosate. Southern blot and western blot analyses confirmed gene integration and expression in T0 transgenic Brassica plants. Transgenic plants exhibited increased resistance to glyphosate compared with untransformed plants. Our results also indicated the aroA‐M1 mutant gene may be a useful selectable marker for the transformation of plants and for the production of herbicide‐resistant plants.
Sunflower Seed Weight and Oil Concentration under Different Post‐Flowering Source‐Sink Ratios
Authors: Ruiz Ricardo Adolfo , Maddonni Gustavo Angel
Published: February 2006

Sunflower (Helianthus annuus L.) seed weight and oil concentration are commonly related to post‐flowering source of assimilates (e.g., leaf area index duration, LAD). A predictive variable including both the source of assimilates and the sinks (i.e., seed number) would better account for seed weight and seed oil concentration variability of crops with contrasting seed number and canopy size. We established quantitative relationships between oil weight per seed components and post‐flowering source–sink ratio. Field experiments were conducted in Argentina from 1998 to 2001. Four hybrids were cultivated under contrasting plant populations and nutrient supplies. A wide range of LAD (913–3130 m2°Cd m−2), seed number (4270–8880 seeds m−2), and seed weight (41–62 mg) was recorded. In contrast, seed oil concentration was not modified (about 530 mg g−1). Post‐flowering source–sink ratio (LAD per seed) better accounted (r2 = 0.69) for seed‐weight prediction than LAD (r2 = 0.42). Maximum seed weight (60 mg) was attained with source–sink ratios ≥0.33 m2°Cd seed−1 Results from our data set pooled together with others of different agro‐ecological regions reveal that sunflower crops are normally growing under limiting post‐flowering source–sink ratios and a 47% reduction of seed weight occurs when post‐flowering source–sink ratio is dramatically (100%) reduced. Seed weight is only 23% increased at saturated source–sink ratios. In contrast, for the wide range of post‐flowering source–sink ratios analyzed, seed oil concentration did not vary.
Spectral Reflectance Methodology in Comparison to Traditional Soil Analysis
Authors: Nanni Marcos Rafael , Demattê José Alexandre M.
Published: February 2006

Traditional soil analyses are expensive, time‐consuming, and may also result in environmental pollutants. The objective of this study was to develop and evaluate a methodology to measure soil attributes using spectral reflectance (SR) as an alternative to traditional methods. Tropical Brazilian soils were sampled over a 196‐ha area divided into grids. Samples (n = 184) were obtained from the 0‐ to 20‐ and 80‐ to 100‐cm depths and georeferenced. The laboratory SR data were obtained using a Spectroradiometer (400–2 500 nm). Satellite reflectance values were sampled from corrected Landsat Thematic Mapper (TM) images. Particle‐size distribution and chemical analysis (organic matter [OM], cation‐exchange capacity [CEC], total SiO2, Fe2O3, TiO2, sum of cations, cation, and Al saturation) were performed in the laboratory. Statistical analysis and multiple regression equations for soil attribute predictions using radiometric data were developed. Laboratory data used 22 bands and 13 “Reflectance Inflexion Differences, RID” from different wavelength intervals of the optical spectrum. However, the satellite data used only the reflectance of the 1, 2, 3, 4, 5, and 7 TM‐Landsat bands. Multiple regression equations were derived from surface and subsurface soil layers. Estimations of some tropical soil attributes were possible using laboratory spectral analysis. Laboratory SR yielded high correlations with traditional laboratory analyses (R2 > 0.79) for the soil attributes such as clay, sand, TiO2, and Fe2O3 Satellite spectral data correlated well with most of the soil attributes such as clay, Fe2O3, and TiO2 (reaching R2 = 0.72). The use of soil analysis methodology by satellite and/or ground remote sensing constitutes an alternative to traditional routine laboratory analysis.
Arboreal Histosols in Old‐Growth Redwood Forest Canopies, Northern California
Authors: Enloe Heather A. , Graham Robert C. , Sillett Stephen C.
Published: February 2006

Within the canopy of old‐growth redwood (Sequoia sempervirens[D. Don] Endl.) forests, accumulations of plant debris in crotches and on massive limbs serve as parent materials for “arboreal soils” up to 1 m thick and over 50 m above the forest floor. These soils are important habitats and water sources for desiccation‐sensitive organisms in the forest canopy ecosystem. We investigated two of these arboreal soils to better understand how they form and function. The primary vascular epiphyte growing in these soils is leather‐leaf fern (Polypodium scouleri). Fern biomass and redwood leaves and bark are the main parent materials of the soils, which are entirely organic. The soils have distinct horizons and soil structure, and have been changed from their initial parent materials as a result of additions, losses, and transformations of organic matter. They are classified as Typic Udifolists. The soils become more decomposed with depth as fibrous components transition to sapric materials. They have low bulk densities (0.07–0.16 g cm−3) and lose most of their water at relatively high matric potentials. Field water contents and potentials of the arboreal soil materials taken near the end of the dry season indicate that water remains available for uptake by ferns. High base saturation values (>55%) suggest that nutrients are available for plant uptake. The soils are extremely acidic, with pH values around 3.0 in 0.01MCaCl2Decomposition may be hindered by the low soil pH and by relatively low soil moisture contents in surface horizons during the dry season.
Use of Spectral Analysis to Detect Changes in Spatial Variability of Forest Floor Properties
Authors: Périé Catherine , Munson Alison D. , Caron Jean
Published: February 2006

Understanding how silvicultural interventions affect soil spatial variability will improve our ability to predict forest ecosystem function in response to different degrees of management intensity. We demonstrate the use of spectral analysis, a geostatistical technique, to understand how management interventions affect soil spatial variability. The technique was applied to determine whether an intensive vegetation control treatment modifies the spatial patterns of soil microclimate and soil quality indicators: microbial biomass C (SMB‐C) and N (SMB‐N) as well as net N mineralization rate. A secondary objective was to investigate the contribution of soil microclimate factors to the explanation of spatial patterns of microbial biomass (C and N). Measurements were performed on transects laid out in two plots: a plot that was undisturbed since clearcut and replanted 11‐yr earlier with white pine (Pinus strobusL.) and another plot which was subject to annual herbicide application during 4 yr following reforestation with white pine. Forest floor temperature (TEMP) and water content (WC), net N mineralization rate and SMB‐C and SMB‐N concentrations were measured every 25 cm along each transect. Spatial patterns were assessed using spectral analysis. In the two plots, microclimatic variables and SMB‐N presented complex spatial patterns with several scales of spatial dependency, whereas SMB‐C and net N mineralization did not demonstrate a spatial pattern at this scale of observation. In the herbicide‐treated plot, the spatial pattern of SMB‐N was influenced by the plantation grid. Herbicide applications markedly decreased spatial variability of forest floor properties. In some frequencies, SMB‐N was markedly positively correlated with forest floor layer WC but not with forest floor TEMP.
Soil Nitrogen Cycling following Montane Forest Conversion in Central Sulawesi, Indonesia
Authors: Corre Marife D. , Dechert Georg , Veldkamp Edzo
Published: February 2006

The lower montane forest zone of Indonesia is undergoing rapid conversion of indigenous forests to agriculture. In this tropical region, however, the effects of forest conversion on soil N processes have not been investigated. Corn (Zea mays L.) and cacao (Theobroma cacao L.)–coffee (Coffea canephora Pierre ex Froehner) agroforestry are the main land use types in cleared lower montane forests in Central Sulawesi, Indonesia. Our main objective was to compare the soil N dynamics under agroforest systems and corn cultivation with indigenous forest. We measured the gross rates of N transformation processes using 15N pool dilution. The agroforest systems and indigenous forests had higher gross N mineralization rates and faster turnover rates of NH4+ and microbial N pools than the long‐term cultivated corn sites. Faster soil N turnover rates in agroforest systems suggest a more dynamic soil N cycling. Leguminous shade trees, which are important components of these agroforest systems, may have influenced the fast microbial N cycling through release of N‐rich root exudates and plant residues. Our results show that compared with corn, agroforestry is a better option in terms of sustainability in the N‐supplying capacity of the soil. In addition, we measured higher 15NH4+ recoveries than 15NO3− recoveries after 15 min of 15N addition in all our sites. Our measured rates of gross nitrification were very low to negligible, due to rapid disappearance of added 15NO3− Such fast reaction of NO3− warrants further investigation, especially in tropical areas where 15N studies are very few.
Denitrification in Marsh‐Pond‐Marsh Constructed Wetlands Treating Swine Wastewater at Different Loading Rates
Authors: Hunt P. G. , Poach M. E. , Matheny T. A. , Reddy G. B. , Stone K. C.
Published: February 2006

Denitrification in constructed wetlands can be very important in the treatment of swine lagoon effluent when land application areas are limited. The objectives of this investigation were to determine (i) the denitrification enzyme activity (DEA) in the marsh sediments of marsh‐pond‐marsh (MPM) constructed wetlands, (ii) changes in DEA with additions of carbon and nitrate, and (iii) the response of DEA to different wastewater N loading rates. Swine wastewater was applied to six MPM wetlands located at North Carolina A&T State University, Greensboro, NC, at rates of 4 to 35 kg N ha−1d−1Soil samples were obtained from the top 25 mm of the marsh sections on four dates for determination of DEA via the acetylene blockage method (blocked at N2O). Headspace N2O was measured via gas chromatography. In the control treatment, they ranged from 0.06 to 1.13 and 0.16 to 0.79 mg N2O‐N kg−1soil hr−1in the first and second marshes, respectively. In both marshes, the DEA rate was significantly increased with the addition of nitrate but not by glucose, indicating that nitrate was a clear limiting factor for denitrification. The DEA in both the control and the amended treatments increased dramatically with increased wastewater N loading, and the increases were generally more pronounced in the first marsh. The DEA values produced in the absence of acetylene blockage did not increase with wastewater N loading rate. Denitrification enzyme activity levels in the marsh sections of the MPM were generally consistent with a highly denitrifying environment.
Mutual Interactions of Sulfate, Oxalate, Citrate, and Phosphate on Synthetic and Natural Allophanes
Authors: Jara Alejandra A. , Violante Antonio , Pigna Massimo , de la Luz Mora María
Published: February 2006

In soil environments, particularly at the soil–plant interface, organic and inorganic ligands may compete with each other for sorption sites onto soil components. The interaction between two or more ligands has a great importance for understanding the adsorption/desorption processes of a given ligand in soil. We studied the mutual interaction of sulfate (SO4), oxalate (OX), citrate (CIT), and phosphate (PO4) in binary and ternary systems on synthetic and natural allophanic samples at different pH values (4.0–7.0). The adsorption capacity of SO4, CIT, and OX (in the order listed) was much lower than that of PO4, but CIT decreased the zero point charge (ZPC) more than OX, meanwhile PO4 increased the ZPC, whereas SO4 did not change the ZPC of the sorbents. The adsorption of SO4 was strongly inhibited in the presence of equimolar amounts of OX, CIT, or PO4 even at low surface coverage of all the ligands. The lower the final pH of the binary systems, the greater the inhibition of SO4 adsorption. The capacity of CIT to prevent SO4 adsorption (ranging from 22–63%) was similar or slightly greater than that of PO4 (ranging from 25–48%) but clearly higher than OX (ranging from 20–42%). On the contrary, SO4 very poorly prevented the adsorption of the other ligands (usually lower than 10%). The effectiveness of the other ligands in retarding or inhibiting SO4 adsorption on an Andisol sample containing 40% allophane decreased with increases in the reaction time. However, even after 15 d of reaction CIT (38%) prevented SO4 adsorption more than PO4 (27%) or OX (12%) did. Our results seem to demonstrate that changes in the electric potential of the surfaces after the addition of anions, as well as competition for adsorption sites, affected the reduction in adsorption of SO4 and the other ligands. However, competition in adsorption with SO4 for common adsorption sites was greater for the organic ligands than for PO4, because the surface coverage of PO4 was particularly low with respect to that of SO4, CIT, and OX.
Soil Organic Carbon Changes in Diversified Rotations of the Western Corn Belt
Authors: Varvel G. E.
Published: February 2006

Sequestration and storage of carbon (C) by agricultural soils has been cited as one potential part of the solution to soil degradation and global climate change. However, C sequestration in soils is a slow and dynamic process. The objective of this study was to evaluate the effects of crop rotation and N fertilizer management on soil organic C (SOC) levels at several points in time during 18 yr of a long‐term study in the Western Corn Belt. Seven cropping systems (three monoculture, two 2‐yr, and two 4‐yr rotations) with three levels of N fertilizer were compared. Soil samples were taken in the spring in 1984, 1992, 1998, and 2002 to a depth of 30 cm in 0‐ to 7.5‐, 7.5‐ to 15‐, and 15‐ to 30‐cm increments. No differences were obtained in SOC levels in 1984 at the beginning of the study. After 8 yr, rotation significantly increased SOC 449 kg ha−1 across all cropping systems. From 1992 to 2002, SOC levels in the 0‐ to 7.5‐cm depth decreased by 516 kg ha−1 across all cropping systems. Soil organic C levels in the 7.5‐ to 15‐cm depths in 1992 and 2002 demonstrated similar rotation effects to those in the surface 0‐ to 7.5‐cm, being not significantly affected from 1984 to 1992 but being significantly decreased from 1992 to 2002 (568 kg SOC ha−1 across all cropping systems). Many of the SOC gains in the surface 30 cm measured during the first 8 yr of the study were lost during the next 10 yr in all but the 4‐yr cropping systems after 18 yr. The loss of SOC in this latter period occurred when depth of tillage was increased by using a tandem disk with larger‐diameter disks. These results demonstrate that more than one point‐in‐time measurement from long‐term experiments is necessary to monitor SOC changes when several management variables, such as cropping system and N fertilizer, are being used. They also indicate that apparent small changes in cultural practices, such as in depth of tillage in this experiment, can significantly change SOC dynamics in the soil. Subtle changes in cultural practices (e.g., tillage depth) can have significant long‐term results, but long‐term experiments are required to quantify their impact under variable climatic conditions.
Soil Organic Nitrogen Enrichment Following Soybean in an Iowa Corn–Soybean Rotation
Authors: Martens Dean A. , Jaynes Dan B. , Colvin Thomas S. , Kaspar Thomas C. , Karlen Douglas L.
Published: February 2006

Understanding soil organic N (ON) pool enrichment may help explain why rates of N fertilization required to attain maximum corn (Zea maysL.) yields are usually lower for corn following soybean [Glycine max(L.) Merr.] than for corn following corn. Our objectives were to quantify the ON pools within a 16‐ha Iowa field and to correlate those results with corn yield. Spring and fall measurements of ON content (0–15 cm soil) as amino acids (AAs), amino sugars (ASs), and NH4+were made using samples collected between 1997 and 1999 from 10 soil map units. The chemical extraction method determined an average 87% of the total N content (n= 10 soils) as identified ON but gave reduced ON recovery from depression soils that experienced periods of water ponding. The total AA concentrations measured in May were positively correlated (r2= 0.84,P< 0.01) with corn yield during a dry year (1997) and 7 out of 10 soils provided near maximum yields. A wetter 1999 boosted overall corn yields 6.6% but resulted in a poorer relationship between May AA concentrations and corn yield. Microbial N compounds measured (May 1997) as glucosamine, galactosamine, and ornithine were also positively correlated with corn yield (r2= 0.84, ρ < 0.01;r2= 0.94,P< 0.001;r2= 0.93,P< 0.001, respectively). The ON concentration decreased during corn production from May to September 1997 an average of 367 kg N ha−1but increased following soybean growth in 1998 by 320 kg N ha−1The chemical extraction methodology identified soils that may not require the full amount of N fertilizer currently being applied, thus decreasing the potential for N loss to surface and ground water resources without decreasing opportunities to achieve optimum yield.
Use of the Nonparametric Nearest Neighbor Approach to Estimate Soil Hydraulic Properties
Authors: Nemes Attila , Rawls Walter J. , Pachepsky Yakov A.
Published: February 2006

Nonparametric approaches are being used in various fields to address classification type problems, as well as to estimate continuous variables. One type of the nonparametric lazy learning algorithms, a k‐nearest neighbor (k‐NN) algorithm has been applied to estimate water retention at −33‐ and −1500‐kPa matric potentials. Performance of the algorithm has subsequently been tested against estimations made by a neural network (NNet) model, developed using the same data and input soil attributes. We used a hierarchical set of inputs using soil texture, bulk density (Db), and organic matter (OM) content to avoid possible bias toward one set of inputs, and varied the size of the data set used to develop the NNet models and to run the k‐NN estimation algorithms. Different ‘design‐parameter’ settings, analogous to model parameters have been optimized. The k‐NN technique showed little sensitivity to potential suboptimal settings in terms of how many nearest soils were selected and how those were weighed while formulating the output of the algorithm, as long as extremes were avoided. The optimal settings were, however, dependent on the size of the development/reference data set. The nonparametric k‐NN technique performed mostly equally well with the NNet models, in terms of root‐mean‐squared residuals (RMSRs) and mean residuals (MRs). Gradual reduction of the data set size from 1600 to 100 resulted in only a slight loss of accuracy for both the k‐NN and NNet approaches. The k‐NN technique is a competitive alternative to other techniques to develop pedotransfer functions (PTFs), especially since redevelopment of PTFs is not necessarily needed as new data become available.
Automated Robotic Assay of Phosphomonoesterase Activity in Soils
Authors: Sadowsky M. J. , Koskinen W. C. , Seebinger J. , Barber B. L. , Kandeler E.
Published: February 2006

Phosphorus cycling in most ecosystems is dependent on plant and microbiologically derived phosphatase enzymes, and available P limits both microbial and plant growth. Measurements of enzymes in soil systems are often time‐consuming and labor intensive. In this study, we examined phosphomonoesterase activity in soils using a Zymark XP laboratory robotic system for soil handling, solvent addition and exchange, filtration, incubation, reagent addition, and final sample preparation. Phosphomonoesterase activity was measured using phenyl phosphate as substrate, and samples were analyzed using a 96‐well microplate reader. Results indicated that our robotic system was capable of effectively measuring phosphomonoesterase activity in soils differing in physical and chemical characteristics. The results obtained using manual and robotic procedures were comparable in accuracy and precision. The robotic system decreased labor associated with this assay by about a factor of 4.5 relative to the manual system, with considerable savings on reagent costs and labor.
A Buffer that Mimics the SMP Buffer for Determining Lime Requirement of Soil
Authors: Sikora F. J.
Published: February 2006

The Shoemaker‐McLean‐Pratt (SMP) buffer used for determining lime requirement of soil contains chromium and p‐nitrophenol, which classifies the solution as a hazardous waste. A buffer without hazardous chemicals producing the same pH as SMP buffer would eliminate hazardous waste and have no effect on agronomic interpretation. Chemicals chosen to replace chromium and p‐nitrophenol were 2‐(N‐morpholino)ethanesulfonic acid monohydrate (MES) and imidazole. Acid titrations of SMP buffer and various mixtures of a new buffer were performed to duplicate the acid‐base characteristics of the SMP buffer. The new buffer is adjusted to pH 7.70 and contains 69.6, 13.7, 31.4, 89.3, and 2000 mMof triethanolamine, imidazole, MES monohydrate, acetic acid, and KCl, respectively. Coefficients of determination (r2) for linear regressions of soil‐buffer pH with the new buffer versus SMP buffer on 255 Kentucky and 87 North American Proficiency Testing (NAPT) soils were 0.974 and 0.967, respectively. The linear regression equation for new buffer versus SMP buffer lime recommendations in Mg ha−1wasy= 0.226 + 0.994xwith anr2of 0.935 for 158 Kentucky soils requiring lime andy= 1.42 + 0.876xwith anr2of 0.876 for 27 NAPT soils requiring lime. Repeated soil‐buffer pH measurements were made using 10 Kentucky soils and 11 NAPT soils over 150 d. Only one of the soil samples showed a significant drift in soil‐buffer pH with time using the new buffer, and the drift was also observed using SMP buffer. With 88 measurements of soil‐buffer pH using the new buffer on 11 NAPT soils, 2 measurements fell outside NAPT warning limits for SMP soil‐buffer pH. The new buffer without hazardous chemicals mimicked the soil‐buffer pH obtained with SMP buffer, provided lime recommendations similar to that with SMP buffer, and had a laboratory shelf life of at least 150 d.
Trans‐Disciplinary Soil Physics Research Critical to Synthesis and Modeling of Agricultural Systems
Authors: Ahuja Lajpat R. , Ma Liwang , Timlin Dennis J.
Published: February 2006

Synthesis and quantification of disciplinary knowledge at the whole system level, via the process models of agricultural systems, are critical to achieving improved and dynamic management and production systems that address the environmental concerns and global issues of the 21st century. Soil physicists have made significant contributions in this area in the past, and are uniquely capable of making the much‐needed and exciting new contributions. Most of the exciting new research opportunities are trans‐disciplinary, that is, lie on the interfacial boundaries of soil physics and other disciplines, especially in quantifying interactions among soil physical processes, plant and atmospheric processes, and agricultural management practices. Some important knowledge‐gap and cutting‐edge areas of such research are: (1) quantification and modeling the effects of various management practices (e.g., tillage, no‐tillage, crop residues, and rooting patterns) on soil properties and soil–plant–atmosphere processes; (2) the dynamics of soil structure, especially soil cracks and biochannels, and their effects on surface runoff of water and mass, and preferential water and chemical transport to subsurface waters; (3) biophysics of changes in properties and processes at the soil–plant and plant–atmosphere interfaces; (4) modeling contributions of agricultural soils to climate change and effects of climate change on soil environment and agriculture; and (5) physical (cause‐effect) quantification of spatial variability of soil properties and their outcomes, new methods of parameterizing a variable field for field‐scale modeling, and new innovative methods of aggregating output results from plots to fields to larger scales. The current status of the various aspects of these research areas is reviewed briefly. The future challenges are identified that will require both experimental research and development of new concepts, theories, and models.
Matrix metalloproteinase-9 activity in the cerebrospinal fluid and serum of dogs with acute spinal cord trauma from intervertebral disk disease
Authors: Levine Jonathan M. , Ruaux Craig G. , Bergman Robert L. , Coates Joan R. , Steiner Jörg M. , Williams David A.
Published: February 2006

Objective—To detect matrix metalloproteinase (MMP)-9 in serum and CSF and determine relationships between MMP activity and severity of disease, duration of clinical signs, and duration of hospitalization in dogs with acute intervertebral disk disease (IVDD).

Animals—35 dogs with acute IVDD and 8 clinically normal control dogs.

Procedure—CSF and serum were collected from affected and control dogs. Zymography was used to detect MMP-9.

Results—Activity of MMP-9 in CSF was detected in 6 of 35 dogs with IVDD; activity was significantly more common in dogs with duration of signs < 24 hours. Paraplegic dogs were more likely to have MMP-9 activity in the CSF than non-paraplegic dogs. No significant difference in hospitalization time was detected in dogs with IVDD between those with and without activity of MMP-9 in the CSF. Serum MMP-9 was detected more frequently in dogs with IVDD than in control dogs.

Conclusions and Clinical Relevance—Data were consistent with results of experimental rodent spinal cord injury studies that indicate that MMP-9 is expressed early during secondary injury.
Evaluation of concentration of voriconazole in aqueous humor after topical and oral administration in horses
Authors: Clode Alison B. , Davis Jennifer L. , Salmon Jacklyn , Michau Tammy Miller , Gilger Brian C.
Published: February 2006

Objective—To determine penetration of topically and orally administered voriconazole into ocular tissues and evaluate concentrations of the drug in blood and signs of toxicosis after topical application in horses.

Animals—11 healthy adult horses.

Procedure—Each eye in 6 horses was treated with a single concentration (0.5%, 1.0%, or 3.0%) of a topically administered voriconazole solution every 4 hours for 7 doses. Anterior chamber paracentesis was performed and plasma samples were collected after application of the final dose. Voriconazole concentrations in aqueous humor (AH) and plasma were measured via high-performance liquid chromatography. Five horses received a single orally administered dose of voriconazole (4 mg/kg); anterior chamber paracentesis was performed, and voriconazole concentrations in AH were measured.

Results—Mean ± SD voriconazole concentrations in AH after topical administration of 0.5%, 1.0%, and 3.0% solutions (n = 4 eyes for each concentration) were 1.43 ± 0.37 μg/mL, 2.35 ± 0.78 μg/mL, and 2.40 ± 0.29 μg/mL, respectively. The 1.0% and 3.0% solutions resulted in significantly higher AH concentrations than the 0.5% solution, and only the 3.0% solution induced signs of ocular toxicosis. Voriconazole was detected in the plasma for 1 hour after the final topically administered dose of all solutions. Mean ± SD voriconazole concentration in AH after a single orally administered dose was 0.86 ± 0.22 μg/mL.

Conclusions and Clinical Relevance—Results indicated that voriconazole effectively penetrated the cornea in clinically normal eyes and reached detectable concentrations in the AH after topical administration. The drug also penetrated noninflamed equine eyes after oral administration. Low plasma concentrations of voriconazole were detected after topical administration.
Assessment of glutamate loss from the ganglion cell layer of young DBA/2J mice with glaucoma
Authors: Low Heather C. , Gionfriddo Juliet R. , Madl James E.
Published: February 2006

Objective—To determine whether glutamate contents are decreased in the ganglion cell layer (GCL) of retinas of DBA/2J mice with glaucoma, compared with unaffected control mice.

Sample Population—20 eyes from DBA/2J mice (9-week-old mice [n = 8] and 4- [4], 6- [4], and 12-month-old [4] mice) and 17 eyes from control CD-1 (7) and C57/BL6 (10) mice of similar age.

Procedure—After euthanasia, the eyes were rapidly dissected and fixed. Serial 0.5-μm sections were prepared from eyecups and stained with toluidine blue (to identify damaged cells) or immunogold (to localize glutamate). Microscopic images were captured digitally for comparison; immunostaining densities were assessed via special software.

Results—In the GCL of control mice, few cells appeared damaged; large amounts of glutamate were detected in 83 ± 8.3% of cells. In DBA/2J mice ≥ 9 weeks of age, damaged neurons were observed in retinal sections; the level of glutamate immunoreactivity was high in a few cells near areas of damage (13 ± 3.2%) and in many cells in less-damaged regions of the same sections (82 ± 4.2%). Many neurons with low amounts of glutamate in damaged regions did not appear damaged histologically.

Conclusions and Clinical Relevance—In retinas of young DBA/2J mice, damaged and undamaged GCL cells had decreased levels of immunostaining for glutamate, compared with less-damaged adjacent regions or retinas from control mice. The loss of neuronal glutamate in damaged retinal regions suggests that glutamate is contributing to early retinal damage prior to changes in intraocular pressure.
Blood lipid concentrations and lipoprotein patterns in captive and wild American black bears (Ursus americanus)
Authors: Frank Nicholas , Elliott Sarah B. , Allin Shawn B. , Ramsay Edward C.
Published: February 2006

Objective—To compare blood lipid concentrations and lipoprotein patterns for captive and wild American black bears (Ursus americanus).

Animals—7 captive and 9 wild adult (≥ 4 years old) black bears.

Procedure—Blood was collected from 2 groups of captive black bears (groups A and B) and 1 group of wild black bears (group C). Blood triglyceride (TG) and cholesterol concentrations were compared among groups. Plasma lipoproteins were isolated by use of a self-generating gradient of iodixanol, and lipoprotein patterns were compared between groups A and B.

Results—Captive bears (mean ± SD, 187.8 ± 44.4 kg) weighed significantly more than wild bears (mean, 104.8 ± 41.4 kg), but mean body weight did not differ between groups A and B. Mean blood TG concentrations for groups B (216.8 ± 16.0 mg/dL) and C (190.7 ± 34.0 mg/dL) were significantly higher than that of group A (103.9 ± 25.3 mg/dL). Mean blood cholesterol concentration was also significantly higher for group B (227.8 ± 8.2 mg/dL) than for groups A (171.7 ± 35.5 mg/dL) or C (190.8 ± 26.8 mg/dL). Mean very-low-density lipoprotein TG and low-density lipoprotein cholesterol concentrations were 2- and 3-fold higher, respectively, for group B, compared with concentrations for group A.

Conclusions and Clinical Relevance—Blood lipid concentrations vary significantly among populations of black bears. Plasma lipoprotein patterns of captive bears differed significantly between colonies and may have reflected differences in diet or management practices.
Immunohistochemical determination of the expression of endothelin receptors in bronchial smooth muscle and epithelium of healthy horses and horses affected by summer pasture-associated obstructive pulmonary disease
Authors: Polikepahad Sumanth , Paulsen Daniel B. , Moore Rustin M. , Costa Lais R. R. , Venugopal Changaram S.
Published: February 2006

Objective—To immunohistochemically determine the expression of endothelin (ET) receptors in bronchial smooth muscle and epithelium of healthy horses and horses affected by summer pasture-associated obstructive pulmonary disease (SPAOPD).

Sample Population—Tissue specimens obtained from 8 healthy and 8 SPAOPD-affected horses.

Procedure—Horses were examined and assigned to healthy and SPAOPD groups. Horses were then euthanatized, and tissue specimens containing bronchi of approximately 4 to 8 mm in diameter were immediately collected from all lung lobes, fixed in zinc-formalin solution for 12 hours, and embedded in paraffin. Polyclonal primary antibodies against ET-A or ET-B receptors at a dilution of 1:200 and biotinylated IgG secondary antibodies were applied to tissue sections, followed by the addition of an avidin-biotin immunoperoxidase complex. Photographs of the stained slides were digitally recorded and analyzed by use of image analysis software to determine the intensity of staining. Two-way ANOVA was used for statistical analysis.

Results—The left diaphragmatic lung lobe of SPAOPD-affected horses had a significantly greater area of bronchial smooth muscle that immunostained for ET-A, compared with that for healthy horses. All lung lobes of SPAOPD-affected horses, except for the right diaphragmatic lobe, had significantly greater staining for ET-B receptors in bronchial smooth muscle, compared with results for healthy horses.

Conclusions and Clinical Relevance—This study revealed overexpression of ET-A and, in particular, ETB receptors in the bronchial smooth muscle of SPAOPD-affected horses, which suggested upregulation of these receptors. These findings improve our understanding of the role of ET-1 in the pathogenesis of SPAOPD.
Evaluation of Coomassie blue staining of the acrosome of equine and canine spermatozoa
Authors: Brum Andrea M. , Thomas Alysia D. , Sabeur Khalida , Ball Barry A.
Published: February 2006

Objective—To evaluate Coomassie blue staining of the acrosome of equine and canine spermatozoa.

Sample Population—Spermatozoa of 5 mixed-breed male dogs and 3 Thoroughbred stallions.

Procedure—Various proportions of intact and acrosome-damaged spermatozoa were fixed in 2% phosphate-buffered formaldehyde or 4% paraformaldehyde, smeared onto glass slides, and stained with Coomassie blue stain. Acrosomal status (damaged vs intact) was also assessed by use of flow cytometry after staining with fluorescein isothiocyanate-conjugated Pisum sativum agglutinin (FITC-PSA) and propidium iodide. Comparisons were made between percentages of expected and observed acrosome-intact spermatozoa in different proportions of live and flash-frozen samples; the percentages of acrosome-intact spermatozoa as determined by use of Coomassie blue staining and flow cytometry were also compared.

Results—Strong correlations were found between the expected and observed distributions of acrosome-intact spermatozoa when fixed in 4% paraformaldehyde (r2 = 0.93 and 0.89 for canine and equine spermatozoa, respectively) as well as between Coomassie blue-stained cells and those stained with FITC-PSA and assessed by use of flow cytometry (r2 = 0.96 and 0.97 for canine and equine spermatozoa, respectively). However, in canine samples that were fixed in 2% phosphate-buffered formaldehyde, these correlations were weak.

Conclusions and Clinical Relevance—Staining with Coomassie blue stain was a simple and accurate method to evaluate the acrosome in equine and canine spermatozoa after fixation in 4% paraformaldehyde. This assay should be useful in routine evaluation of semen samples from these species.
Priorities for neuropsychiatric genetics at the National Institutes of Health
Authors: Pato Carlos N.
Published: February 2006

Over the last decade, molecular genetics has become one of the most important technologies in medical research. However, the application of these approaches to neuropsychiatric disorders has been met with both unreasonable expectations, and at times, unreasonable criticism. Molecular genetics has opened a new window into these disorders that has great promise, but is likely to reveal a complex reality. Clearly, the potential exists to actually define some of the disorders that make up the syndromes that we are studying. In doing so, we will not only begin to address the fundamental pathophysiology of these disorders, but also begin to design treatments based on this new understanding. In this report, a series of four papers on the genetics programs of the National Institutes of Health will be introduced. © 1994 Wiley‐Liss, Inc.
Schizophrenia and mental retardation associated in a pedigree with retinitis pigmentosa and sensorineural deafness
Authors: Sharp C. W. , Muir W. J. , Blackwood D. H. R. , Walker M. , Gosden C. , St. Clair D. M.
Published: February 2006

A family is presented with multiple cases of mild mental retardation, schizophrenia and other functional psychoses, progressive hearing loss, and retinitis pigmentosa (RP). It closely resembles a previously reported Finnish family. We suggest that the phenotypes are not associated in this family by chance, but define a novel syndrome which may be caused by a mutant allele at a single genetic locus. © 1994 Wiley‐Liss, Inc.
Neurobehavioral characteristics of CGG amplification status in fragile X females
Authors: Thompson Nora M. , Gulley Margaret L. , Rogeness Graham A. , Clayton Robert J. , Johnson Chris , Hazelton Bonnie , Cho Chong G. , Zellmer Vickie T.
Published: February 2006

Neurobehavioral correlates of CGG amplification were studied in 17 nonretarded adult female carriers of fragile X syndrome. The results revealed a significant relationship between IQ and the number of CGG repeats in the 5′ untranslated region of the FMR1 gene. Women with a full mutation (>200 CGG repeats) scored below average in IQ, visual‐spatial perception, visual‐spatial organization, and executive function. There were no differences in fine motor dexterity or memory as a function of CGG amplification status. A history of major depressive disorder was identified in 71% of the sample, but incidence of depression was not associated with the degree of CGG amplification. Schizotypal features were noted in 18%. No intellectual or neuropsychological deficit was found in women with a premutation (<200 CGG repeats). Decrements in IQ, visual‐spatial perception, and executive function appear to arise as a consequence of the CGG amplification.
Initial report of a genome search for the affective disorder predisposition gene in the old order Amish pedigrees: Chromosomes 1 and 11
Authors: Gerhard D. S. , Labuda M. C. , Bland S. D. , Allen C. , Egeland J. A. , Pauls D. L.
Published: February 2006

Family data have suggested that some forms of major affective disorder are genetic. Certain of the Old Order Amish pedigrees have a familial form of the disease. In this report we present the results of genetic analyses under autosomal dominant mode of transmission with reduced pentrance and three different disease hierarchies. The pedigrees were genotyped with 28 markers from chromosome 1 and 23 markers from chromosomes 11. None of the markers result in a significantly positive lod score. © 1994 Wiley‐Liss, Inc.
Recent history of European psychiatry–ideas, developments, and personalities: The annual Eliot Slater lecture
Authors: Strömgren Erik
Published: February 2006

Erik Strömgren had planned to revise and expand his Slater lecture to a more systematic and comprehensive paper for publication. Shortly before his death, he asked for the editorial opinion of one of us (IIG), but unfortunately he did not get the opportunity to complete his lecture manuscript. We find, however, that although kaleidoscopic and impressionistic, the manuscript, as it is, contains historic and autobiographical information of high value, which deserves a posthumous publication, for availability to a broader audience. His wife, Dr. Lizzie Sand Strömgren, has kindly released the manuscript, which here appears essentially as delivered at the Slater lecture in 1986, except for a few minor textual adaptions and the addition of a list of references (by A.B.). © 1994 Wiley‐Liss, Inc.