ABSTRACT The results obtained in spatial analysis of pheromone trap catches of oriental fruit mot... more ABSTRACT The results obtained in spatial analysis of pheromone trap catches of oriental fruit moth, Grapholita molesta (Busck) and Peach twig borer, Anarsia lineatella (Zeller), are reported. The studies were performed in the Molise region, central Italy, during 2002 and 2003. Local distributions of oriental fruit moth and peach twig borer males were considered in a heterogeneous landscape. The aim of the study was to determine the temporal and spatial variation in distribution and abundance of the insect pests inside small plots of fruit orchards (apple, kiwi, peach, pear and plum fruits) and outside (in field crops, irrigation channels, hedgerows and a river), and to evaluate the importance of the host plants in relation to the adult distributions. Results showed that the main ‘hot spot’ for both lepidopterous pests was in a stone fruit orchard in the northern zone of the study area; other infested areas were in stone orchards and, in the case of A. lineatella, also in plum orchards. The river seems to act as a barrier rather than an ecological corridor. The observed spatio-temporal distributions of G. molesta and A. lineatella differed and were determined mainly by the location of the most important host plants and by the tendency of males to move in the environment, i.e. inside and outside the breeding and mating sites. Adequate knowledge of these spatial processes should be considered as an essential prerequisite for integrated pest management programmes in a precision farming approach.
Soil organic matter can modify the interaction of clay minerals with water, limiting the rate of ... more Soil organic matter can modify the interaction of clay minerals with water, limiting the rate of water intake of swelling clays and stabilising soil aggregates. Soil structural stability and organic C content usually decrease with cultivation. Faster wetting increases stresses on aggregates and decreases stability. Aggregate wettabilities of prairie soils under 3 different management systems (grassland, no-till, and conventional-till) were compared in the Northern Great Plains of the USA. Six Ustolls and 2 Usterts were selected as replications along the Missouri River. Wettability was measured as water drop penetration time (WDPT) and as rate of water intake under 30 and 300 mm tension. At low tension, aggregates from both cultivated fields and uncultivated grasslands showed similar wettability. Water intake in grass aggregates was attributed to a greater amount of stable pores relative to cultivated aggregates. In cultivated aggregates, slaking created planes of failure that allowe...
Communications in Soil Science and Plant Analysis, 1997
Understanding the factors that influence soil and plant nitrogen (N) spatial variability may impr... more Understanding the factors that influence soil and plant nitrogen (N) spatial variability may improve our ability to develop management systems that maximize productivity and minimize environmental hazards. The objective of this study was to determine the field (65 ha) scale spatial variability of N and δ 15 N in soil and corn (Zea mays). Soil, grain, and stover samples were collected from grids that ranged in size from 30 by 30 m to 60 by 60 m. Plant samples, collected following physiological maturity in 1995, were analyzed for total N and δ 15 N. Soil samples, collected prior to planting in the spring of 1995 and 1996, were analyzed for inorganic-N, total N, and δ 15 N. All parameters showed strong spatial relationships. In an undrained portion of the field containing somewhat poorly and poorly drained soils there was a net loss of 95 kg N ha -1 , while in an adjacent area that was tile drained there was a net gain of 98 kg N ha -1 . Denitrification and N mineralization most likely were responsible for losses and gains, respectively. Differences between the N balances of these areas (193 kg N ha -1 ) provide a relative measure of the impact of tile drainage on plant N availability and greenhouse gas production in a wet year.
structure of air-dry soils, pedality refers to dry aggregates. Dry aggregation is an important ph... more structure of air-dry soils, pedality refers to dry aggregates. Dry aggregation is an important phase of structure Soil structural stability often decreases as the intensity of cultivation genesis in arid and semiarid soils, where it is transient, increases. The effect of three different management systems (grass, no-till, and till) on soil aggregate stability and sizes were studied in formed only periodically at the surface. Dry aggregation six Ustolls and two Usterts on central South Dakota farms. Soil struc-determines the resistance of the soil to wind erosion ture was morphologically described throughout the profile. Stability since aggregates and particles Ͼ1 mm are less susceptiof dry and wet aggregates in the topsoil was tested by dry and wet ble to wind transport. Dry stability measures the strength sieving. Most structural changes were observed in the top 0 to 0.20 m. of aggregates subjected to fracture and abrasion. Slight Granular structure was dominant under grass, whereas plates, blocks, differences in structural stability can be detected by dry and compacted layers were most common in conventionally tilled sieving (repeated if necessary). Dry sieving has shown and no-till soils. The largest mean weight diameters (MWD) of dry decreased macroaggregate stability after tillage (Chepil, aggregates were found in no-till soils (10 mm vs. 7 in till and 6 in 1962; Degens et al., 1996). On the other hand, measurements of stability to water tivated soils (70%). After about 10 yr of no-till management, no-till soil aggregates were significantly more stable (5% for wet and 32% are generally used to estimate structural changes due to for dry aggregates) than till aggregates only in the top 0 to 0.05 m. The structural stability of cultivated soils was greater in Usterts than breakdown in agricultural soils. At the macroaggregate in Ustolls. scale, wet sieving traditionally provides a measure of size and stability of aggregates produced by the scouring action of water. Results of wet sieving tests may or may
... Jiyul Chang a ,; David E. Clay * a ,; Charles G. Carlson a ,; Sharon A. Clay a ,; Douglas D. ... more ... Jiyul Chang a ,; David E. Clay * a ,; Charles G. Carlson a ,; Sharon A. Clay a ,; Douglas D. Malo a ,; Robert Berg b ,; Jon Kleinjan a and; William Wiebold c. a Plant Science Dep., South Dakota State Univ., Brookings, SD 57007 b Southeast Research Farm, South Dakota Agric. Exp ...
Diagnostic tools for assessing the cause of soybean [Glycine max (L.) Merr.] yield variability in... more Diagnostic tools for assessing the cause of soybean [Glycine max (L.) Merr.] yield variability in whole fields are needed. The objective of this study was to determine if 13 C discrimination (Δ) can be used to assess the factors responsible for soybean yield variability. Research ...
To determine temporal changes in soil nutrient status, reproducible results must be obtained at e... more To determine temporal changes in soil nutrient status, reproducible results must be obtained at each time step. The objective of this paper was to determine the impact of grid distance on the reproducibility of spatial variability measurements. Soil samples from the 0 to 15 cm depth were Ž. collected from a 30 by 30 m grid in May 1995 in a 65 ha notill corn Zea mays L. field. Each bulk sample contained 15 individual cores, collected at sample points located every 11.4 cm along a transect Ž. that transversed 3 corn rows 57 cm. At each sampling point latitude, longitude, elevation, landscape position, and soil series were determined. The 30 m grid was used to develop 4 and 9 independent data sets having a 60 and 90 m grids, respectively. Semivariograms, nugget to sill ratios, and mean squared Ž. errors were calculated for each data set. At 60 m: i the total N, total C, and pH semivariograms, of Ž. different start points, were similar, while semivariograms for Olsen P, K, and Zn were different; ii the spatial dependence ratings, based on the nugget to sill ratio, for total N, total C, and pH semivariograms Ž. were consistent and suggested moderate spatial dependence; iii the spatial dependence rating for Olsen P, K, and Zn for the 4 semivariograms were not consistent and ranged from weak to moderate spatial dependence. At 90 m, all soil nutrients had different semivariograms for each start point, while the spatial dependence rating for each total N, total C, and pH start point were consistent and showed moderate spatial dependence. The total C, P, K, Zn, and pH MSE values at 60 m, were 30, 30, 41, 28, and 72% lower than the variance, respectively. This study showed that semivariogram, semivariance, MSE, and nugget to sill ratios reproducibility were dependent on soil nutrient and grid distance.
Soil carbon (C) losses and soil translocation from tillage operations have been identified as cau... more Soil carbon (C) losses and soil translocation from tillage operations have been identified as causes of soil degradation and soil erosion. The objective of this work was to quantify the variability in tillage-induced carbon dioxide (CO 2 ) loss by moldboard (MP) and chisel (CP) plowing across an eroded landscape and relate the C loss to soil properties. The study site was a 4 ha wheat (Triticum aestivum L. cv. Marshall) field with rolling topography and five soil types in the Svea-Barnes complex in west central Minnesota (N. Latitude = 45841 0 W, Longitude = 95843 0 ). Soil properties were measured at several depths at a 10 m spacing along north-south (N-S) and west-east (W-E) transects through severely eroded, moderately eroded and non-eroded sites. Conventional MP (25 cm deep) and CP (15 cm deep) equipment were used along the pre-marked transects. Gas exchange measurements were obtained with a large, portable chamber within 2 m of each sample site following tillage. The measured CO 2 fluxes were largest with the MP > CP > not tilled (before tillage). The variation in 24 h cumulative CO 2 flux from MP was nearly 3-fold on the N-S transect and 4-fold on the W-E transect. The surface soil organic C on the transects was lowest on the eroded knolls at 5.1 g C kg À1 and increased to 19.6 g C kg À1 in the depositional areas. The lowest CO 2 fluxes were measured from severely eroded sites which indicated that the variation in CO 2 loss was partially reflected by the degradation of soil properties caused by historic tillage-induced soil translocation with some wind and water erosion.
Genetic and immunological analysis of host-pathogen interactions can reveal fundamental mechanism... more Genetic and immunological analysis of host-pathogen interactions can reveal fundamental mechanisms of susceptibility and resistance to infection. Modeling human infectious diseases among inbred mouse strains is a proven approach but is limited by naturally occurring genetic diversity. Using N-ethyl-N-nitrosourea mutagenesis, we created a recessive loss-of-function point mutation in Unc93b1 (unc-93 homolog B1 (C. elegans)), a chaperone for endosomal Toll-like receptors (TLR)3, TLR7 and TLR9, which we termed Letr for 'loss of endosomal TLR response'. We used Unc93b1(Letr/Letr) mice to study the role of Unc93b1 in the immune response to influenza A/PR/8/34 (H1N1), an important global respiratory pathogen. During the early phase of infection, Unc93b1(Letr/Letr) mice had fewer activated exudate macrophages and decreased expression of CXCL10, interferon (IFN)-γ and type I IFN. Mutation of Unc93b1 also led to reduced expression of the CD69 activation marker and a concomitant increa...
Soil organic matter can modify the interaction of clay minerals with water, limiting the rate of ... more Soil organic matter can modify the interaction of clay minerals with water, limiting the rate of water intake of swelling clays and stabilising soil aggregates. Soil structural stability and organic C content usually decrease with cultivation. Faster wetting increases stresses on aggregates and decreases stability. Aggregate wettabilities of prairie soils under 3 different management systems (grassland, no-till, and conventional-till) were compared in the Northern Great Plains of the USA. Six Ustolls and 2 Usterts were selected as replications along the Missouri River. Wettability was measured as water drop penetration time (WDPT) and as rate of water intake under 30 and 300 mm tension. At low tension, aggregates from both cultivated fields and uncultivated grasslands showed similar wettability. Water intake in grass aggregates was attributed to a greater amount of stable pores relative to cultivated aggregates. In cultivated aggregates, slaking created planes of failure that allowed rapid water entry. Differences of wettability between management systems at 300 mm tension (in Ustolls, grasslands had greater wettability than cultivated soils, 0.24 v. 0.17 g water/h.g dry soil) and between soil orders (Usterts had longer WDPT than Ustolls, 2.9 v. 1.7 s) were explained by both clay and organic C contents. Simple measurements of aggregate wettability may be effectively used for soil quality characterisation. Aggregate wettability is a desirable property for agricultural soils when it is related to stable porosity, as may be found in high organic matter soils (e.g. grasslands). Wettability is excessive when fast aggregate wetting results in aggregate destruction as observed in low organic matter cultivated soils. S R 0 3 0 2 9 A . E y n a r d e t a l .W e t t a b i l i t y o f Us t o l l s a n d Us t e r t s Additional keywords: management systems, organic C.
Long-term cultivation impacts soil properties. During the early 1920s a study comparing non-culti... more Long-term cultivation impacts soil properties. During the early 1920s a study comparing non-cultivated and cultivated soils was done in eastern SD (Beadle, McCook, Minnehaha, and Union Counties), USA. The objectives of the current study were to: (1) determine the long-term (>80 years) impact of cultivation on selected soil properties; and (2) establish baseline soil data that can be used for
Soil movement by tillage redistributes soil within the profile and throughout the landscape, resu... more Soil movement by tillage redistributes soil within the profile and throughout the landscape, resulting in soil removal from convex slope positions and soil accumulation in concave slope positions. Previous investigations of the spatial variability in surface soil properties and crop yield in a glacial till landscape in west central Minnesota indicated that wheat (Triticum aestivum) yields were decreased in upper hillslope positions affected by high soil erosion loss. In the present study, soil cores were collected and characterized to indicate the effects of long-term intensive tillage on soil properties as a function of depth and tillage erosion. This study provides quantitative measures of the chemical and physical properties of soil profiles in a landscape subject to prolonged tillage erosion, and compares the properties of soil profiles in areas of differing rates of tillage erosion and an uncultivated hillslope. These comparisons emphasize the influence of soil translocation within the landscape by tillage on soil profile characteristics. Soil profiles in areas subject to soil loss by tillage erosion >20 Mg ha À1 year À1 were characterized by truncated profiles, a shallow depth to the C horizon (mean upper boundary 75 cm from the soil surface), a calcic subsoil and a tilled layer containing $19 g kg À1 of inorganic carbon. In contrast, profiles in areas of soil accumulation by tillage >10 Mg ha À1 year À1 exhibited thick sola with low inorganic carbon content (mean 3 g kg À1 ) and a large depth to the C horizon (usually >1.5 m below the soil surface). When compared to areas of soil accumulation, organic carbon, total nitrogen and Olsen-extractable phosphorus contents measured lower, whereas inorganic carbon content, pH and soil strength measured higher throughout the profile in eroded landscape positions because of the reduced soil organic matter content and the influence of calcic subsoil material. The mean surface soil organic carbon and total nitrogen contents in cultivated areas (regardless of erosion status) were less than half that measured in an uncultivated area, indicating that intensive tillage and cropping has significantly depleted the surface soil organic matter in this landscape. Prolonged intensive tillage and cropping at this site has effectively removed at least 20 cm of soil from the upper hillslope positions. #
The chicken natural resistance-associated macrophage protein 1 (NRAMP1) gene has been mapped by l... more The chicken natural resistance-associated macrophage protein 1 (NRAMP1) gene has been mapped by linkage analysis by use of a reference panel to develop the chicken molecular genetic linkage map and by fluorescence in situ hybridization. The chicken homolog of the murine Nrampl gene was mapped to a linkage group located on Chromosome (Chr) 7q13, which includes three genes (CD28, NDUSF1, and EF1B) that have previously been mapped either to mouse Chr 1 or to human Chr 2q. Physical mapping by pulsed-field gel electrophoresis revealed that NRAMP1 is tightly linked to the villin gene and that the genomic organization (gene order and presence of CpG islands) of the chromosomal region carrying NRAMP1 is well conserved between the chicken and mammalian genomes. The regions on mouse Chr 1, human Chr 2q, and chicken Chr 7q that encompass NRAMP1 represent large conserved chromosomal segments between the mammalian and avian genomes. The chromosome mapping of the chicken NRAMP1 gene is a first step in determining its possible role in differential susceptibility to salmonellosis in this species.
Lipopolysaccharide (LPS), an abundant glycolipid of the outer membrane of gram-negative bacteria,... more Lipopolysaccharide (LPS), an abundant glycolipid of the outer membrane of gram-negative bacteria, is able to provoke a generalized proinflammatory response in the infected host. Genetic regulation of this trait has been localized to the Lps locus on mouse chromosome 4. Several inbred mouse strains, including C3H/HeJ, C57BL/10ScNCr and C57BL/10ScCr, bear mutations at the Lps locus (Lps(d)) that confer hyporesponsiveness to the immunostimulatory properties of LPS and susceptibility to overwhelming gram-negative bacterial infection. The phenotypic expression of Lps(d) is pleiotropic, affecting several cell types crucial to host defense, including the macrophage. By positional cloning, Toll-like receptor 4 (Tlr4), a transmembrane protein with a cytoplasmic domain that bears homology to the Interleukin-1 receptor, has been identified as the gene encoded by Lps. Tlr4 is a member of a novel gene family that participates in host defense against microbial infection in plants, invertebrates and mammals. Discovery of the molecular basis of the Lps mutation represents a significant advance in defining the fundamental mechanisms of cellular activation by LPS.
The mouse response to Salmonella Typhimurium infection is partly controlled through detection of ... more The mouse response to Salmonella Typhimurium infection is partly controlled through detection of the bacterium lipopolysaccharide by the host pattern recognition receptor, Toll-like receptor 4 (Tlr4). Mice deficient in Tlr4 signaling are extremely susceptible to Salmonella infection with a 1,000-fold reduction in LD(50). In a previous study, we showed, using transgenic mice carrying one, three, six and >30 copies of Tlr4, that the level of expression of this gene influences the outcome of Salmonella infection, with a plateau effect starting at three copies. In the present study, we further investigate the impact of Tlr4 during Salmonella infection in mice expressing Tlr4 at slightly sub-normal, normal and slightly supra-normal levels by comparing host responses in mice carrying one, two and three copies of Tlr4 on the same genetic background. We describe in detail the in vivo host response to pathogenic Salmonella and show for the first time, in this narrow range of Tlr4 expression, an incremental protective effect against Salmonella due to improved control of bacterial growth in target organs and increased expression of important immune response genes in the spleen.
In humans, Salmonella infection causes two major clinical diseases, typhoid fever and a self-limi... more In humans, Salmonella infection causes two major clinical diseases, typhoid fever and a self-limiting gastro-enteritidis. Salmonella transmission occurs by the fecal-oral route and the interactions between the bacteria and the digestive tract epithelium are central to the outcome of the infection. Using a mouse model of typhoid fever, we previously identified a mutation in USP18 affecting type I interferon (IFN) signaling resulting in increased susceptibility to systemic Salmonella infection. In this study, we demonstrate the effects of this mutation during the early response to Salmonella using a model of typhlitis. Mutant Usp18 mice showed a minimal inflammatory response early after Salmonella Typhimurium infection that was associated with low pathologic scores and low IFN-g production. This resulted in an increased interaction of Salmonella with the cecal epithelium and earlier systemic dissemination of the bacteria. The global transcriptional signature in the cecum of mouse during Salmonella infection showed normal expression of tissue specific genes and upregulation of type I IFN pathway in mutant mice. In control mice, there was a significant over-representation of genes involved in cellular recruitment and antibacterial activity paralleling the histopathological features. These results show the impact of USP18 in the development of Salmonella-induced typhlitis.
ABSTRACT The results obtained in spatial analysis of pheromone trap catches of oriental fruit mot... more ABSTRACT The results obtained in spatial analysis of pheromone trap catches of oriental fruit moth, Grapholita molesta (Busck) and Peach twig borer, Anarsia lineatella (Zeller), are reported. The studies were performed in the Molise region, central Italy, during 2002 and 2003. Local distributions of oriental fruit moth and peach twig borer males were considered in a heterogeneous landscape. The aim of the study was to determine the temporal and spatial variation in distribution and abundance of the insect pests inside small plots of fruit orchards (apple, kiwi, peach, pear and plum fruits) and outside (in field crops, irrigation channels, hedgerows and a river), and to evaluate the importance of the host plants in relation to the adult distributions. Results showed that the main ‘hot spot’ for both lepidopterous pests was in a stone fruit orchard in the northern zone of the study area; other infested areas were in stone orchards and, in the case of A. lineatella, also in plum orchards. The river seems to act as a barrier rather than an ecological corridor. The observed spatio-temporal distributions of G. molesta and A. lineatella differed and were determined mainly by the location of the most important host plants and by the tendency of males to move in the environment, i.e. inside and outside the breeding and mating sites. Adequate knowledge of these spatial processes should be considered as an essential prerequisite for integrated pest management programmes in a precision farming approach.
Soil organic matter can modify the interaction of clay minerals with water, limiting the rate of ... more Soil organic matter can modify the interaction of clay minerals with water, limiting the rate of water intake of swelling clays and stabilising soil aggregates. Soil structural stability and organic C content usually decrease with cultivation. Faster wetting increases stresses on aggregates and decreases stability. Aggregate wettabilities of prairie soils under 3 different management systems (grassland, no-till, and conventional-till) were compared in the Northern Great Plains of the USA. Six Ustolls and 2 Usterts were selected as replications along the Missouri River. Wettability was measured as water drop penetration time (WDPT) and as rate of water intake under 30 and 300 mm tension. At low tension, aggregates from both cultivated fields and uncultivated grasslands showed similar wettability. Water intake in grass aggregates was attributed to a greater amount of stable pores relative to cultivated aggregates. In cultivated aggregates, slaking created planes of failure that allowe...
Communications in Soil Science and Plant Analysis, 1997
Understanding the factors that influence soil and plant nitrogen (N) spatial variability may impr... more Understanding the factors that influence soil and plant nitrogen (N) spatial variability may improve our ability to develop management systems that maximize productivity and minimize environmental hazards. The objective of this study was to determine the field (65 ha) scale spatial variability of N and δ 15 N in soil and corn (Zea mays). Soil, grain, and stover samples were collected from grids that ranged in size from 30 by 30 m to 60 by 60 m. Plant samples, collected following physiological maturity in 1995, were analyzed for total N and δ 15 N. Soil samples, collected prior to planting in the spring of 1995 and 1996, were analyzed for inorganic-N, total N, and δ 15 N. All parameters showed strong spatial relationships. In an undrained portion of the field containing somewhat poorly and poorly drained soils there was a net loss of 95 kg N ha -1 , while in an adjacent area that was tile drained there was a net gain of 98 kg N ha -1 . Denitrification and N mineralization most likely were responsible for losses and gains, respectively. Differences between the N balances of these areas (193 kg N ha -1 ) provide a relative measure of the impact of tile drainage on plant N availability and greenhouse gas production in a wet year.
structure of air-dry soils, pedality refers to dry aggregates. Dry aggregation is an important ph... more structure of air-dry soils, pedality refers to dry aggregates. Dry aggregation is an important phase of structure Soil structural stability often decreases as the intensity of cultivation genesis in arid and semiarid soils, where it is transient, increases. The effect of three different management systems (grass, no-till, and till) on soil aggregate stability and sizes were studied in formed only periodically at the surface. Dry aggregation six Ustolls and two Usterts on central South Dakota farms. Soil struc-determines the resistance of the soil to wind erosion ture was morphologically described throughout the profile. Stability since aggregates and particles Ͼ1 mm are less susceptiof dry and wet aggregates in the topsoil was tested by dry and wet ble to wind transport. Dry stability measures the strength sieving. Most structural changes were observed in the top 0 to 0.20 m. of aggregates subjected to fracture and abrasion. Slight Granular structure was dominant under grass, whereas plates, blocks, differences in structural stability can be detected by dry and compacted layers were most common in conventionally tilled sieving (repeated if necessary). Dry sieving has shown and no-till soils. The largest mean weight diameters (MWD) of dry decreased macroaggregate stability after tillage (Chepil, aggregates were found in no-till soils (10 mm vs. 7 in till and 6 in 1962; Degens et al., 1996). On the other hand, measurements of stability to water tivated soils (70%). After about 10 yr of no-till management, no-till soil aggregates were significantly more stable (5% for wet and 32% are generally used to estimate structural changes due to for dry aggregates) than till aggregates only in the top 0 to 0.05 m. The structural stability of cultivated soils was greater in Usterts than breakdown in agricultural soils. At the macroaggregate in Ustolls. scale, wet sieving traditionally provides a measure of size and stability of aggregates produced by the scouring action of water. Results of wet sieving tests may or may
... Jiyul Chang a ,; David E. Clay * a ,; Charles G. Carlson a ,; Sharon A. Clay a ,; Douglas D. ... more ... Jiyul Chang a ,; David E. Clay * a ,; Charles G. Carlson a ,; Sharon A. Clay a ,; Douglas D. Malo a ,; Robert Berg b ,; Jon Kleinjan a and; William Wiebold c. a Plant Science Dep., South Dakota State Univ., Brookings, SD 57007 b Southeast Research Farm, South Dakota Agric. Exp ...
Diagnostic tools for assessing the cause of soybean [Glycine max (L.) Merr.] yield variability in... more Diagnostic tools for assessing the cause of soybean [Glycine max (L.) Merr.] yield variability in whole fields are needed. The objective of this study was to determine if 13 C discrimination (Δ) can be used to assess the factors responsible for soybean yield variability. Research ...
To determine temporal changes in soil nutrient status, reproducible results must be obtained at e... more To determine temporal changes in soil nutrient status, reproducible results must be obtained at each time step. The objective of this paper was to determine the impact of grid distance on the reproducibility of spatial variability measurements. Soil samples from the 0 to 15 cm depth were Ž. collected from a 30 by 30 m grid in May 1995 in a 65 ha notill corn Zea mays L. field. Each bulk sample contained 15 individual cores, collected at sample points located every 11.4 cm along a transect Ž. that transversed 3 corn rows 57 cm. At each sampling point latitude, longitude, elevation, landscape position, and soil series were determined. The 30 m grid was used to develop 4 and 9 independent data sets having a 60 and 90 m grids, respectively. Semivariograms, nugget to sill ratios, and mean squared Ž. errors were calculated for each data set. At 60 m: i the total N, total C, and pH semivariograms, of Ž. different start points, were similar, while semivariograms for Olsen P, K, and Zn were different; ii the spatial dependence ratings, based on the nugget to sill ratio, for total N, total C, and pH semivariograms Ž. were consistent and suggested moderate spatial dependence; iii the spatial dependence rating for Olsen P, K, and Zn for the 4 semivariograms were not consistent and ranged from weak to moderate spatial dependence. At 90 m, all soil nutrients had different semivariograms for each start point, while the spatial dependence rating for each total N, total C, and pH start point were consistent and showed moderate spatial dependence. The total C, P, K, Zn, and pH MSE values at 60 m, were 30, 30, 41, 28, and 72% lower than the variance, respectively. This study showed that semivariogram, semivariance, MSE, and nugget to sill ratios reproducibility were dependent on soil nutrient and grid distance.
Soil carbon (C) losses and soil translocation from tillage operations have been identified as cau... more Soil carbon (C) losses and soil translocation from tillage operations have been identified as causes of soil degradation and soil erosion. The objective of this work was to quantify the variability in tillage-induced carbon dioxide (CO 2 ) loss by moldboard (MP) and chisel (CP) plowing across an eroded landscape and relate the C loss to soil properties. The study site was a 4 ha wheat (Triticum aestivum L. cv. Marshall) field with rolling topography and five soil types in the Svea-Barnes complex in west central Minnesota (N. Latitude = 45841 0 W, Longitude = 95843 0 ). Soil properties were measured at several depths at a 10 m spacing along north-south (N-S) and west-east (W-E) transects through severely eroded, moderately eroded and non-eroded sites. Conventional MP (25 cm deep) and CP (15 cm deep) equipment were used along the pre-marked transects. Gas exchange measurements were obtained with a large, portable chamber within 2 m of each sample site following tillage. The measured CO 2 fluxes were largest with the MP > CP > not tilled (before tillage). The variation in 24 h cumulative CO 2 flux from MP was nearly 3-fold on the N-S transect and 4-fold on the W-E transect. The surface soil organic C on the transects was lowest on the eroded knolls at 5.1 g C kg À1 and increased to 19.6 g C kg À1 in the depositional areas. The lowest CO 2 fluxes were measured from severely eroded sites which indicated that the variation in CO 2 loss was partially reflected by the degradation of soil properties caused by historic tillage-induced soil translocation with some wind and water erosion.
Genetic and immunological analysis of host-pathogen interactions can reveal fundamental mechanism... more Genetic and immunological analysis of host-pathogen interactions can reveal fundamental mechanisms of susceptibility and resistance to infection. Modeling human infectious diseases among inbred mouse strains is a proven approach but is limited by naturally occurring genetic diversity. Using N-ethyl-N-nitrosourea mutagenesis, we created a recessive loss-of-function point mutation in Unc93b1 (unc-93 homolog B1 (C. elegans)), a chaperone for endosomal Toll-like receptors (TLR)3, TLR7 and TLR9, which we termed Letr for 'loss of endosomal TLR response'. We used Unc93b1(Letr/Letr) mice to study the role of Unc93b1 in the immune response to influenza A/PR/8/34 (H1N1), an important global respiratory pathogen. During the early phase of infection, Unc93b1(Letr/Letr) mice had fewer activated exudate macrophages and decreased expression of CXCL10, interferon (IFN)-γ and type I IFN. Mutation of Unc93b1 also led to reduced expression of the CD69 activation marker and a concomitant increa...
Soil organic matter can modify the interaction of clay minerals with water, limiting the rate of ... more Soil organic matter can modify the interaction of clay minerals with water, limiting the rate of water intake of swelling clays and stabilising soil aggregates. Soil structural stability and organic C content usually decrease with cultivation. Faster wetting increases stresses on aggregates and decreases stability. Aggregate wettabilities of prairie soils under 3 different management systems (grassland, no-till, and conventional-till) were compared in the Northern Great Plains of the USA. Six Ustolls and 2 Usterts were selected as replications along the Missouri River. Wettability was measured as water drop penetration time (WDPT) and as rate of water intake under 30 and 300 mm tension. At low tension, aggregates from both cultivated fields and uncultivated grasslands showed similar wettability. Water intake in grass aggregates was attributed to a greater amount of stable pores relative to cultivated aggregates. In cultivated aggregates, slaking created planes of failure that allowed rapid water entry. Differences of wettability between management systems at 300 mm tension (in Ustolls, grasslands had greater wettability than cultivated soils, 0.24 v. 0.17 g water/h.g dry soil) and between soil orders (Usterts had longer WDPT than Ustolls, 2.9 v. 1.7 s) were explained by both clay and organic C contents. Simple measurements of aggregate wettability may be effectively used for soil quality characterisation. Aggregate wettability is a desirable property for agricultural soils when it is related to stable porosity, as may be found in high organic matter soils (e.g. grasslands). Wettability is excessive when fast aggregate wetting results in aggregate destruction as observed in low organic matter cultivated soils. S R 0 3 0 2 9 A . E y n a r d e t a l .W e t t a b i l i t y o f Us t o l l s a n d Us t e r t s Additional keywords: management systems, organic C.
Long-term cultivation impacts soil properties. During the early 1920s a study comparing non-culti... more Long-term cultivation impacts soil properties. During the early 1920s a study comparing non-cultivated and cultivated soils was done in eastern SD (Beadle, McCook, Minnehaha, and Union Counties), USA. The objectives of the current study were to: (1) determine the long-term (>80 years) impact of cultivation on selected soil properties; and (2) establish baseline soil data that can be used for
Soil movement by tillage redistributes soil within the profile and throughout the landscape, resu... more Soil movement by tillage redistributes soil within the profile and throughout the landscape, resulting in soil removal from convex slope positions and soil accumulation in concave slope positions. Previous investigations of the spatial variability in surface soil properties and crop yield in a glacial till landscape in west central Minnesota indicated that wheat (Triticum aestivum) yields were decreased in upper hillslope positions affected by high soil erosion loss. In the present study, soil cores were collected and characterized to indicate the effects of long-term intensive tillage on soil properties as a function of depth and tillage erosion. This study provides quantitative measures of the chemical and physical properties of soil profiles in a landscape subject to prolonged tillage erosion, and compares the properties of soil profiles in areas of differing rates of tillage erosion and an uncultivated hillslope. These comparisons emphasize the influence of soil translocation within the landscape by tillage on soil profile characteristics. Soil profiles in areas subject to soil loss by tillage erosion >20 Mg ha À1 year À1 were characterized by truncated profiles, a shallow depth to the C horizon (mean upper boundary 75 cm from the soil surface), a calcic subsoil and a tilled layer containing $19 g kg À1 of inorganic carbon. In contrast, profiles in areas of soil accumulation by tillage >10 Mg ha À1 year À1 exhibited thick sola with low inorganic carbon content (mean 3 g kg À1 ) and a large depth to the C horizon (usually >1.5 m below the soil surface). When compared to areas of soil accumulation, organic carbon, total nitrogen and Olsen-extractable phosphorus contents measured lower, whereas inorganic carbon content, pH and soil strength measured higher throughout the profile in eroded landscape positions because of the reduced soil organic matter content and the influence of calcic subsoil material. The mean surface soil organic carbon and total nitrogen contents in cultivated areas (regardless of erosion status) were less than half that measured in an uncultivated area, indicating that intensive tillage and cropping has significantly depleted the surface soil organic matter in this landscape. Prolonged intensive tillage and cropping at this site has effectively removed at least 20 cm of soil from the upper hillslope positions. #
The chicken natural resistance-associated macrophage protein 1 (NRAMP1) gene has been mapped by l... more The chicken natural resistance-associated macrophage protein 1 (NRAMP1) gene has been mapped by linkage analysis by use of a reference panel to develop the chicken molecular genetic linkage map and by fluorescence in situ hybridization. The chicken homolog of the murine Nrampl gene was mapped to a linkage group located on Chromosome (Chr) 7q13, which includes three genes (CD28, NDUSF1, and EF1B) that have previously been mapped either to mouse Chr 1 or to human Chr 2q. Physical mapping by pulsed-field gel electrophoresis revealed that NRAMP1 is tightly linked to the villin gene and that the genomic organization (gene order and presence of CpG islands) of the chromosomal region carrying NRAMP1 is well conserved between the chicken and mammalian genomes. The regions on mouse Chr 1, human Chr 2q, and chicken Chr 7q that encompass NRAMP1 represent large conserved chromosomal segments between the mammalian and avian genomes. The chromosome mapping of the chicken NRAMP1 gene is a first step in determining its possible role in differential susceptibility to salmonellosis in this species.
Lipopolysaccharide (LPS), an abundant glycolipid of the outer membrane of gram-negative bacteria,... more Lipopolysaccharide (LPS), an abundant glycolipid of the outer membrane of gram-negative bacteria, is able to provoke a generalized proinflammatory response in the infected host. Genetic regulation of this trait has been localized to the Lps locus on mouse chromosome 4. Several inbred mouse strains, including C3H/HeJ, C57BL/10ScNCr and C57BL/10ScCr, bear mutations at the Lps locus (Lps(d)) that confer hyporesponsiveness to the immunostimulatory properties of LPS and susceptibility to overwhelming gram-negative bacterial infection. The phenotypic expression of Lps(d) is pleiotropic, affecting several cell types crucial to host defense, including the macrophage. By positional cloning, Toll-like receptor 4 (Tlr4), a transmembrane protein with a cytoplasmic domain that bears homology to the Interleukin-1 receptor, has been identified as the gene encoded by Lps. Tlr4 is a member of a novel gene family that participates in host defense against microbial infection in plants, invertebrates and mammals. Discovery of the molecular basis of the Lps mutation represents a significant advance in defining the fundamental mechanisms of cellular activation by LPS.
The mouse response to Salmonella Typhimurium infection is partly controlled through detection of ... more The mouse response to Salmonella Typhimurium infection is partly controlled through detection of the bacterium lipopolysaccharide by the host pattern recognition receptor, Toll-like receptor 4 (Tlr4). Mice deficient in Tlr4 signaling are extremely susceptible to Salmonella infection with a 1,000-fold reduction in LD(50). In a previous study, we showed, using transgenic mice carrying one, three, six and >30 copies of Tlr4, that the level of expression of this gene influences the outcome of Salmonella infection, with a plateau effect starting at three copies. In the present study, we further investigate the impact of Tlr4 during Salmonella infection in mice expressing Tlr4 at slightly sub-normal, normal and slightly supra-normal levels by comparing host responses in mice carrying one, two and three copies of Tlr4 on the same genetic background. We describe in detail the in vivo host response to pathogenic Salmonella and show for the first time, in this narrow range of Tlr4 expression, an incremental protective effect against Salmonella due to improved control of bacterial growth in target organs and increased expression of important immune response genes in the spleen.
In humans, Salmonella infection causes two major clinical diseases, typhoid fever and a self-limi... more In humans, Salmonella infection causes two major clinical diseases, typhoid fever and a self-limiting gastro-enteritidis. Salmonella transmission occurs by the fecal-oral route and the interactions between the bacteria and the digestive tract epithelium are central to the outcome of the infection. Using a mouse model of typhoid fever, we previously identified a mutation in USP18 affecting type I interferon (IFN) signaling resulting in increased susceptibility to systemic Salmonella infection. In this study, we demonstrate the effects of this mutation during the early response to Salmonella using a model of typhlitis. Mutant Usp18 mice showed a minimal inflammatory response early after Salmonella Typhimurium infection that was associated with low pathologic scores and low IFN-g production. This resulted in an increased interaction of Salmonella with the cecal epithelium and earlier systemic dissemination of the bacteria. The global transcriptional signature in the cecum of mouse during Salmonella infection showed normal expression of tissue specific genes and upregulation of type I IFN pathway in mutant mice. In control mice, there was a significant over-representation of genes involved in cellular recruitment and antibacterial activity paralleling the histopathological features. These results show the impact of USP18 in the development of Salmonella-induced typhlitis.
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Papers by D. Malo