Using Factor Analysis to Characterise Historical Trends of Trace Metal Contamination in a Sediment Core from the Tagus Prodelta,Portugal

Water, Air, & Soil Pollution - It is well established that the livestock sector is a major contributor to greenhouse gases (GHG) and ammonia (NH3) emissions. In this paper, the evolution of...     

Vertical distribution of the plant-parasitic nematode, Meloidogyne chitwoodi, under field crops

The root-knot nematode Meloidogyne chitwoodi is a severe pest on sandy soils in Belgium and causes quality damage to economically important crops such as carrot, potato and black salsify. Pre-planting soil sampling to detect infestations has proven useful to farmers when taking decisions on the crop rotation. To develop an adequate sampling strategy, the vertical distribution of M. chitwoodi was examined under summer barley, carrot, fodder beet, bean, marigold and black fallow on two fields with a sandy soil. Soil samples were collected at monthly intervals from April 2004 to April 2006. Cores were taken to a depth of 70 cm and split into 10 cm segments. Nematodes were extracted by zonal centrifugation. Fodder beet increased the population of M. chitwoodi immensely; carrot was also a good host. Barley was a moderate host and under bean and marigolds the population decreased. The relative distribution of M. chitwoodi over the different soil layers during two successive years was consistent in each field. The different successions with good, moderate and poor hosts did not influence this distribution significantly. A logistic model was fitted to the mean cumulative percentages of nematodes at increasing soil depth. Farmers are advised to take soil samples for detection of M. chitwoodi immediately after harvest, especially after crops with a long field period. Adapting the depth of the cores taken to the vertical distribution of the population can increase the chances of detection. Our results suggest that this distribution is persistent in crop rotations and depends on field characteristics.     

The impact of atmospheric deposition and climate on forest growth in European monitoring plots: An individual tree growth model

In the climate change discussion, the possibility of carbon sequestration of forests plays an important role. Therefore, research on the effects of environmental changes on net primary productivity is interesting. In this study we investigated the influence of changing temperature, precipitation and deposition of sulphur and nitrogen compounds on forest growth. The database consisted of 654 plots of the European intensive monitoring program (Level II plots) with 5-year growth data for the period 1994–1999. Among these 654 plots only 382 plots in 18 European countries met the requirements necessary to be used in our analysis. Our analysis was done for common beech (Fagus sylvatica), oak (Quercus petraea and Q. robur), Scots pine (Pinus sylvestris) and Norway spruce (Picea abies). We developed an individual tree growth model with measured basal area increment of each individual tree as responding growth factor and tree size (diameter at breast height), tree competition (basal area of larger trees and stand density index), site factors (soil C/N ratio, temperature), and environmental factors (temperature change compared to long-term average, nitrogen and sulphur deposition) as influencing parameters. Using a mixed model approach, all models for the tree species show a high goodness of fit with Pseudo-R² between 0.33 and 0.44. Diameter at breast height and basal area of larger trees were highly influential variables in all models. Increasing temperature shows a positive effect on growth for all species except Norway spruce. Nitrogen deposition shows a positive impact on growth for all four species. This influence was significant with p < 0.05 for all species except common beech. For beech the effect was nearly significant (p = 0.077). An increase of 1 kg N ha⁻¹ yr⁻¹ corresponds to an increase in basal area increment between 1.20% and 1.49% depending on species. Considering an average total carbon uptake for European forests near 1730 kg per hectare and year, this implies an estimated sequestration of approximately 21–26 kg carbon per kg nitrogen deposition.     

Fate of the insecticide lambda-cyhalothrin in ditch enclosures differing in vegetation density

Use of the insecticide lambda-cyhalothrin in agriculture may result in the contamination of water bodies, for example by spray drift. Therefore, the possible exposure of aquatic organisms to this insecticide needs to be evaluated. The exposure of the organisms may be reduced by the strong sorption of the insecticide to organic materials and its susceptibility to hydrolysis at the high pH values in the natural range. In experiments done in May and August, formulated lambda-cyhalothrin was mixed with the water body of enclosures in experimental ditches containing a bottom layer and macrophytes (at different densities) or phytoplankton. Concentrations of lambda-cyhalothrin in the water body and in the sediment layer, and contents in the plant compartment, were measured by gas-liquid chromatography at various times up to 1 week after application. Various water quality parameters were also measured. Concentrations of lambda-cyhalothrin decreased rapidly in the water column: 1 day after application, 24-40% of the dose remained in the water, and by 3 days it had declined to 1.8-6.5%. At the highest plant density, lambda-cyhalothrin residue in the plant compartment reached a maximum of 50% of the dose after 1 day; at intermediate and low plant densities, this maximum was only 3-11% of the dose (after 1-2 days). The percentage of the insecticide in the ditch sediment was 12% or less of the dose and tended to be lower at higher plant densities. Alkaline hydrolysis in the water near the surface of macrophytes and phytoplankton is considered to be the main dissipation process for lambda-cyhalothrin.     

Oral immunisation of pigs with fimbrial antigens of enterotoxigenic E. coli: an interesting model to study mucosal immune mechanisms

The intestinal mucosal immune system can discriminate actively between harmful pathogenic agents and harmless food antigens resulting in different immune responses namely IgA production and oral tolerance, respectively. Recently, a pig model has been developed for studying intestinal mucosal immune responses in which F4 fimbrial antigens of enterotoxigenic Escherichia coli (F4 ETEC) are used as oral antigens. A unique feature of this model is that soluble F4 antigens can be administered to pigs which have a receptor for this fimbriae (F4R(+)) on their small intestinal villous enterocytes and pigs which do not have this receptor (F4R(-)). Oral administration of F4 to the F4R(+) pigs results in an intestinal mucosal immune response that completely protects the pigs against a challenge infection. In F4R(-) pigs such an intestinal mucosal immune response does not occur. However, a priming of the systemic immune system can be seen similar to the priming in pigs fed with the same dose of a food antigen, suggesting that F4 in F4R(-) pigs behaves as a food antigen. The fact that different mucosal immune responses can be induced with soluble F4, makes it an interesting model to study mucosal immune mechanisms in the pig.     

Histologic and micro-computed tomographic evaluation of the osseointegration of a nonresorbable bone substitute in alveoli of ponies after tooth extraction

OBJECTIVE: To evaluate the biological behavior of a nonresorbable bone substitute (NRBS) in the alveoli of ponies, compared with tissue quality in naturally healing alveoli, after cheek tooth extraction. ANIMALS: 5 clinically normal ponies. PROCEDURES: In each pony, both maxillary fourth premolars (Triadan 108/208) were repulsed bilaterally during anesthesia. One randomly chosen alveolus was filled with NRBS and isolated from the oral cavity by use of dental impression material and a spring-wire retention device. The other alveolus was occluded in its occlusal third portion with dental impression material. One year after surgery, cylindrical lateromedial biopsy specimens were collected from the apical, middle, and occlusal level of each alveolus. Biopsy samples were evaluated for bone mineral density and bone volume via micro-computed tomography; qualitative histologic characteristics were evaluated via light microscopy. RESULTS: Bone mineral density and bone volume were greater in control alveoli, compared with NRBS-treated alveoli. Control alveoli were characterized by the presence of few mature bone trabeculae and wide spaces containing fat tissue and mesenchymal stroma. In treated alveoli, biocompatibility and osteoconductive properties of the NRBS were excellent; continuous bone formation and bone remodeling were also evident. CONCLUSIONS AND CLINICAL RELEVANCE: Results indicated that the NRBS was integrated well in calcified alveolar tissues in ponies 1 year after maxillary cheek tooth extraction. Further research is necessary to establish the benefits of this NRBS in the development of a dental implant surgical technique in equids.     

Transcytosis of F4 fimbriae by villous and dome epithelia in F4-receptor positive pigs supports importance of receptor-dependent endocytosis in oral immunization strategies

Very few antigens have been described that induce an intestinal immunity when given orally. Our laboratory demonstrated that oral administration of isolated F4 (K88) fimbriae of Escherichia coli to F4-receptor positive (F4R(+)) pigs induces protective mucosal immunity against challenge infection. However, presence of F4-receptors (F4R) on villous enterocytes is a prerequisite for inducing the immune response, as no F4-specific antibody-secreting cells (ASC) can be induced in F4R(-) pigs. In this study, the in vivo binding of isolated F4 fimbriae (F4) to the gut epithelium was examined in F4R(+) and F4R(-) pigs. It was further investigated whether binding of F4 to the F4R results in endocytosis in and translocation across the gut epithelium using microscopy. F4 did not adhere to the intestinal epithelium of F4R(-) pigs, whereas it strongly adhered to the villous epithelium and the follicle-associated epithelium (FAE) of the jejunum and ileum of F4R(+) pigs. Following binding to F4R, F4 was endocytosed by villous enterocytes, follicle-associated enterocytes and M cells. Transcytosis of F4 across the epithelium resulted in the appearance of F4 in the lamina propria and dome region of the jejunal and ileal PP. This is the first study showing transcytosis of fimbriae across the gut epithelium. This receptor-dependent transcytosis can explain the success of F4 fimbriae as oral immunogen for inducing protective immunity in F4R(+) pigs strengthening the importance of receptor-dependent endocytosis and translocation in oral vaccine strategies. Further identification of the receptor responsible for this transport is in progress.     

Cartilage canals in the medial coronoid process of young Golden Retrievers

The aim of the study was to establish the location of cartilage canals in the medial coronoid process (MCP) of the ulna of young Golden Retrievers, a breed that is predisposed to fractures of the medial coronoid process (FMCP). To determine whether the presence of cartilage canals could be associated with the predilection site of FMCP, the right elbows of nine young Golden Retrievers (aged 4, 6, 8, 10, 13, 16, 18, 22 and 24 weeks) were dissected and, with no prior decalcification, the formaldehyde-fixed MCPs were embedded in methylmethacrylate. The entire MCPs were serially sectioned in the frontal plane from cranial to caudal and the sections (5 microm) were routinely stained. Between the ages of 5 and 10 weeks, three main cartilage canals were visible--medial, central and lateral. All originated from the periosteum of the distal parts of the MCP and ended proximally under the articular cartilage. Branches of the main canals were seen more cranially and caudally. At the age of 13 weeks, the central canal was absent, and the remaining canals showed a smaller diameter. From 16 weeks onwards, no cartilage canals were seen. No direct relationship could be established between the predilection site of FMCP (lateral part of the MCP) and the presence/absence of cartilage canals, since both medial and lateral canals disappeared at the same age. Further research is needed to elucidate the pathogenesis of FMCP.     

Multiple Uses of Water in Irrigated Areas

Although irrigation systems have long been evaluated andmanaged as though they existed only to produce irrigatedcrops, in fact many irrigation systems also provide water forother uses, especially in much of Asia. The quantities ofwater used in these activities may be small, but these useshave high value in terms of household income, nutrition, andhealth. Recognizing the multiple uses of water in irrigationsystems is critical for better water allocation policy. First,the value of water in irrigation systems has been undervaluedbecause of a failure to recognize the many uses. A moreaccurate assessment that includes all uses will better informdecisions about allocating water (and financial resources)between irrigation and other uses. Second, even withinirrigation systems, taking all uses into account can lead tomore productive and environmentally sustainable use of water.Third, recognizing the rights of all users of water can leadto more equitable and socially sustainable outcomes ofmanagement, rehabilitation, and any proposed reallocation ofwater resources. Recognizing all uses of water makes watermanagement and economic and institutional analyses morecomplex. Because many of the interactions between uses areaffected by water quality at least as much as quantity, italso brings environmental and health issues to the fore. Thisarticle reviews these issues, drawing upon the case studyarticles from Sri Lanka and India, which are presented in thisspecial issue.     

Comparison of the in vitro pathogenicity of two Salmonella Typhimurium phage types

The in vitro pathogenicity of Salmonella enterica serovar Typhimurium phage type (pt) 90 and pt 506 (also known as DT 104) isolates from human and porcine origin was studied in adhesion and invasion assays to the human cell line Caco-2 and the porcine cell line IPI-2. Interleukin-8 (IL-8) production by these two cell lines in response to stimulation by the two Salmonella phage types was also measured. Generally, Salmonella Typhimurium pt 506 and pt 90 adhered to and invaded Caco-2 cells and IPI-2 cells equally well. The release of IL-8 by Caco-2 cells or by IPI-2 cells was similar, independent of the Salmonella phage type used for stimulation of the cells. These data suggest that Salmonella Typhimurium pt 90 has a similar ability to cause Salmonella infections as Salmonella Typhimurium DT 104.