Adherence of Actinobacillus pleuropneumoniae serotype 1 to swine buccal epithelial cells involves fibronectin

The swine pathogen Actinobacillus pleuropneumoniae serotype 1 was investigated for its ability to adhere to swine, rat, and human buccal epithelial cells (BEC). The highest number of bacteria adhered was to swine BEC. This binding ability was affected by heating, extreme pH, treatment with sodium dodecyl sulfate, ethylenediamine tetraacetate, or periodate, and proteolysis, suggesting that cell-surface glycoproteins participate in adherence and that adherence is based mostly on ionic interactions. Mannose and swine fibronectin may play a direct role in this interaction. Convalescent-phase serum from naturally infected pigs inhibited the adhesion. There was a correlation between bacterial pathogenicity as well as host specificity and the capacity for adherence to swine BEC. Adhesion to swine BEC provides a convenient method to study in vitro the adherence of A. pleuropneumoniae and other pathogens of the pig respiratory tract.     

Uncertainty in Paleoecological Studies of Mercury in Sediment Cores

Increased recognition of the ecological damage of mercury (Hg) has focused attention on quantifying spatial and temporal patterns of Hg deposition. Studies are commonly based on core chronologies and use a combination of techniques to measure parameters such as bulk density, percent solids, Hg concentration, and radionuclide activity. Little attention is generally devoted to the propagated error associated with these measurements. We identified the impact of sources of uncertainty on stratigraphic Hg determinations for Florida Everglades and Lake Erie cores. Large errors may be introduced by converting wet sample Hg content to dry-weight concentrations. Drying of sediments at 55 °C caused Hg losses of 18%. Samples, air-dried at room temperature, retained considerable moisture and required corrections for remaining water content. Frozen sediments did not lose Hg during a 72-day storage. Random error in radionuclide analysis of cores resulted in dating uncertainty of ±1.2 yr in 10 yr old deposits. This error increased to ±20 yr in 100 yr old sediments. Propagation of small errors in each step of the analysis (while adhering to strict QA/QC criteria) produced compounded uncertainties of ±11 and ±29% in Hg concentrations under different analytical rigor, and errors of up to ±73% in Hg accumulation rates in older sediments. Enrichment factors, comparing uncertain recent and historic Hg accumulation rates, differed by as much as ±48%. Uncertainty in paleoecological studies of mercury needs to be documented in order to correctly evaluate trends and remediation efforts.     

Irrigation restriction effects on water use efficiency and osmotic adjustment in Aloe Vera plants (Aloe barbadensis Miller)

Aloe barbadensis Miller, known as Aloe Vera, requires limited irrigation depending on the capacity of the soil to retain humidity, since it is a CAM species and thus naturally adapted to conditions of dryness and high temperatures. Therefore, we postulated that plants of Aloe Vera plants under conditions of water deficit should improve their water use efficiency (WUE) by performing osmotic adjustment (OA) with a temporal correlation between WUE and OA. The objective of the investigation was to determine the effect of water restriction on the WUE and OA of A. barbadensis under different water treatments. 18-month old Aloe Vera plants were cultivated in pots with a soil substrate that was a mixture of equal parts of sand and organic matter with 18% of FC and 9% of permanent wilting point. To determine the effects of the soil humidity on plant WUE and OA, four treatments were arranged in a complete random design with four repetitions; these were 100%, 75%, 50% and 25% of FC, which correspond to an evatranspiration of 11.4, 9.6, 4.0 and 1.7 L per plant, respectively. The water treatments were maintained by frequent irrigation. The following variables were determined: dry matter, leaf water potential, relative water content (RWC), amount of gel produced, sap flow, proline content, soluble and total sugars and oligo and polyfructans. Aloe Vera increased WUE with increasing water deficit; the sap flow rate decreased with water restrictions, and the plants performed osmotic adjustment by increasing the synthesis of proline, soluble and total sugars as well as the amounts of oligo and polyfructans, mainly polymers of β-(2 → 6) kestotriose, changing from the inulin type to the neofructan type. The plants most and less irrigated (100% and 25% of FC) were the groups with lowest WUE. The plants irrigated with 75% of FC presented the best WUE in terms of dry mass and amount of gel produced by a litre of supplied water.     

Organic priority pollutants in groundwater and surface water at three landfills in north central Florida

The occurence of organic priority pollutants in groundwater and surface water impacted by municipal landfill leachate was studied at the Orange County Landfill in Orange County, Florida. The results of the investigation were compared to existing data from two municipal landfills in Alachua County, Florida. The investigation in Orange County evaluated existing wells and surface water stations through sampling of groundwater, surface water, sediment, and aquatic biota. Very few organic priority pollutants were detected. The constituents most frequently found were volatile organic compounds, particularly aromatic organic constituents. Volatile organic compounds were detected in groundwater at total concentrations of less than 100 Μg L^?1. Few base/neutral and acid extractable organic priority pollutants were detected. Data from the Alachua County landfills indicated the presence of volatile organic compounds in groundwater at both landfill sites but few organic priority pollutants in the base/neutral and acid extractable group were fouund. Any organic priority pollutants that were present in the solid waste as deposited were likely metabolized by microorganisms or otherwise degraded, sorbed on particulate matter, or diluted to such an extent as to be non-detected.     

The influence of hydrological conditions on dissolved and suspended constituents in the Missouri River

Physical and chemical constituents of the Missouri River near Brownville, Neb. U.S.A. were studied during the period May, 1970 through December, 1972. Considerable variation in river discharge was observed. The changing hydrological conditions affected the concentrations of both the dissolved and suspended constituents in the river. Rain and snowmelt runoff increased the river discharge and also contributed to increased turbidity and total suspended solids. A number of parameters including total phosphorus, total organic nitrogen, oxygen demand and certain metals correlated with increased suspended solids. However, most of the major anions and cations measured showed decreased concentrations as a result of increased river discharge.     

Effects of cold environment and intake level on the energetic efficiency of feedlot steers.

The effects of cold climatic conditions on energy partitioning were investigated with 49 Hereford-type steers fed an all-concentrate, barley-based diet in a 2 x 3 factorial comparative slaughter trial. Steers (seven per treatment) were kept either indoors or outdoors (n = 2) and fed at 50, 65, or 80 g of DM/kg of BW.75 (n = 3) for up to 106 d. Mean temperatures were 16.9 +/- 2.7 degrees C and -7.6 +/- 6.8 degrees C in indoor and outdoor locations, respectively. Steers housed indoors grew 49% faster (P less than .001) and had 51% better gain: feed ratios (P less than .05) than those kept outdoors. Outdoor steers retained 65% less (P less than .001) energy. Estimated fasting heat production in the outdoor steers was 18% higher (P less than .01) and efficiency of ME use for maintenance 14% lower (P less than .01) than in the indoor steers, which resulted in an estimated increase of 41% in the ME requirements for maintenance in the outdoor steers. The NEg content of the diet was decreased from 1.29 Mcal/kg in the indoor steers to .76 Mcal/kg in the outdoor steers. Outdoor steers deposited 21% of their energy as protein, whereas indoor steers deposited only 14% of their energy as protein, which could explain the low NEg value of the diet in the cold environment. It was concluded that the main factors contributing to reduced energetic efficiency in the cold were an increased maintenance requirement and a greater proportion of the dietary energy retained as protein.     

Mercury accumulation trends in Florida Everglades and Savannas Marsh flooded soils

Global and regional increases in atmospheric mercury (Hg) concentrations have previously been identified as the cause of increased mercury accumulation rates in north temperate lakes in Sweden, Wisconsin, and Minnesota. Atmospheric deposition can often account for elevated Hg concentrations in fish from these systems. Mercury levels in sportfish collected from some areas of the Florida Everglades and Savannas Marsh exceed limits that are acceptable for human consumption. Forty five soil cores and soil grab samples were retrieved from the Everglades and Savannas Marsh wetlands. Eighteen sediment cores were dated radiochemically with²¹⁰Pb and¹³⁷Cs using γ-ray spectroscopy to determine modern and historic mercury accumulation rates for these subtropical wetland systems. Recent (“post-1985”) Hg accumulation rates averaged 53 μg m^?2 y^?1 (23 to 141, n=18) corresponding to an average rate increase of 4.9 times (1.6 to 19.1) over those observed around the turn of the century. This accumulation seems to result more from either global or regional atmospheric deposition rather than from lateral transport via overlying surface water. The trends for mercury accumulation match those reported for lakes in Sweden and the northern United States, even though these systems are distinctly different in their climate, vegetational composition, and location. We provide the first data on accumulation of mercury in subtropical wetland systems, and demonstrate the feasibility of radiochemical dating of wetland sediment.     

Genetic evaluation of length of productive life in the Spanish Holstein-Friesian population. Model validation and genetic parameters estimation

Functional longevity (FL), measured as length of productive life (LPL) adjusted by production level, has been regarded as an important trait to measure the global functional aptitude of a cow, particularly when direct measures of the functional traits (health and reproductive performance) are not available. The objective of this study was to analyze the trait FL making use of survival analysis techniques in order to propose a model for the genetic evaluation of this trait in the Spanish Holstein Friesian population. The data set consisted of 133,629 registered cows of three regions; Andalusia, Basque Country and Catalonia. The hazard function was described as the product of a baseline hazard function and the time-independent effects of age at first calving, lactation number-stage of lactation, annual change in herd size, milk, fat and protein yield. Sire and maternal grandsire and herd-year-season of calving were considered as random effects. Percentage of right-censored data ranged from 41.9% to 52.7% for the analysed data sets. All the effects analyzed were significant (P < 0.0001) and had a great influence on the risk of culling of a cow, except for the age at first calving which showed a relatively small effect. Higher risk for factors such as age at first calving, change in herd size and relative level of milk production was associated with the more extreme classes. The consistency of the results among regional samples which represent diverse production systems in the population indicated that the proposed model could be applied at the national level. The relatively low heritability (0.048 to 0.074) suggests that genetic improvement of LPL could be effective if the direct evaluation is combined with indirect measures of LPL.