Contamination of Urban Soils in an Area of Northern France Polluted by Dust Emissions of Two Smelters

The contamination of 27 urban topsoils has been assessed around two lead and zinc smelters (Metaleurop Nord and Umicore) in the North of France. Eighteen trace elements have been analysed (Ag, As, Bi, Cd, Co, Cr, Cu, Hg, In, Ni, Pb, Sb, Se, Sn, Tl, Th, U and Zn). The investigation included the study of the vertical distribution of Cd, Pb and Zn as indicators of pollution. It was shown that Cd, In, Pb, Sb and Zn were major pollutants followed in lesser quantities by Ag, Bi, Cu and Hg. In addition, As, Ni, Se, Sn and Tl were present at levels slightly higher than regional agricultural values. The other elements (Co, Cr, Th and U) were at endogenous levels. The observations have highlighted the strong heterogeneity of the physico-chemical parameters of urban soils and the existence of heavy contamination of the under layers by Cd, Pb and Zn. A potential transfer of metals from the topsoil to the deeper layers and especially Cd and Zn, is not excluded. Indeed the soil rework is not the only factor explaining contamination level of the deeper layers of the studied soils. The comparison of the studied element concentrations in urban soils with nearby local agricultural values shows that the dust emission originating from the Metaleurop and Umicore smelters were not the only source of contamination. Thus a large contamination of the studied urban soils by Sb and In could be explained by domestic combustion of coal for heating.     

磷改良剂对中度和高度含碳酸盐的菜园土壤中Cd和Pb环境有效性和植物有效性的影响

The behaviour of metals mainly depends on soil p H, carbonate contents and contamination level, which should be considered for the management of contaminated soils. In this study, kitchen garden topsoils(0–25 cm) were sampled from the area around three smelters in France, with different Cd and Pb contamination levels. Effect of a phosphate amendment(a mixture of diammonium phosphate and hydroxyapatite) on the environmental availability and phytoavailability of Cd and Pb was evaluated by different chemical extractions and cultivating lettuce(Lactuca sativa L.), respectively. Changes in the distribution of Cd and Pb were found in most contaminated soils after phosphate amendment. An increase of Cd and Pb in the residual phase was highlighted in almost all carbonated contaminated soils, whereas a decrease of Pb in the exchangeable, water and acid-soluble phase was observed in most contaminated soils with the lowest carbonate contents. The concentrations of extractable Cd and Pb using calcium chloride and acetic and citric acids generally decreased after the soil amendment. Lettuces grown on amended soils were acceptable for human consumption as regard to Pb concentration. In contrast, some lettuces were unacceptable for human consumption, since the concentrations of Cd in the leaves were higher than the European legislation limit. Surprisingly, in carbonated soils with very low concentration of Cd, the Cd concentrations in lettuce reached up to the European legislation limit, making the lettuce unacceptable for human consumption.Our study highlighted the fact that the total metal concentration in soils does not always allow to predict the metal accumulation in the edible parts of vegetables in order to make a judgement about their acceptability or unacceptability for human consumption.     

Mass Transfer of Carbaryl from Pure Water to Salt Aqueous Solution: Result Comparison Between Sea and Lab-Made Water

It is well known that mass transfer of a solid compound into a liquid phase is characterized by mutual properties of both sides. Solubilization capacity of the liquid phase is primary affected by its composition in inorganic species inducing salting in/out effect evaluated by Setschenow constant, generally defined at 298.15 K. On the other hand, the equilibrium process is highly influenced by polar compatibility issue. Therefore, the study of such transfer is essential in order to set the role of each party participating in the solid–liquid equilibrium. Thus, a comparison of transfer magnitude and feasibility of carbaryl from pure water, to seawater, and lab-made seawater was held. To do so, solubility of the compound was experimented at different temperature in multiple media. Solubility determination is based on the saturation of a specific heated fluid passing through a saturation cell. The solute transported is subsequently trapped in a specific extraction column. Back flashing method is then applied to dissolve the compound. After validation, aqueous solubility of carbaryl was studied as function of temperature ranging from (273.15 to 318.15 K) at atmospheric pressure. In addition, solubility was determined in pure, seawater, and corresponding lab-made water, thus solubility values ranged from 3.57E-06 to 3.49E-05 in pure water, from 3.04E-06 to 2.53E-05 in seawater and from 6.51E-06 to 3.61E-05 in lab-made water. As a result, thermophysical properties of transfer and usage of lab-made water on the mass transfer properties divergence was spotted. The Salting out phenomenon observed for carbaryl was interpreted by the internal pressure theory that suggests the reduction of internal cavities in the presence of salt, making solubilization process more difficult to achieve. Thus, showing an overall endogenic process with a positive Gibbs free energy of transfer that is highly affected by the magnitude of salting out effect and the temperature. The molar entropy of transfer increases versus temperature caused by the disorder of solvent molecules due to the dissolution process.     

Pathogens at the livestock-wildlife interface in Western Alberta: does transmission route matter?

In southwestern Alberta, interactions between beef cattle and free-ranging elk (Cervus elaphus) may provide opportunities for pathogen transmission. To assess the importance of the transmission route on the potential for interspecies transmission, we conducted a cross-sectional study on four endemic livestock pathogens with three different transmission routes: Bovine Viral Diarrhea Virus and Bovine Herpesvirus 1 (predominantly direct transmission), Mycobacterium avium subsp. paratuberculosis (MAP) (indirect fecal-oral transmission), Neospora caninum (indirect transmission with definitive host). We assessed the occurrence of these pathogens in 28 cow-calf operations exposed or non-exposed to elk, and in 10 elk herds exposed or not to cattle. We characterized the effect of species commingling as a risk factor of pathogen exposure and documented the perceived risk of pathogen transmission at this wildlife-livestock interface in the rural community. Herpesviruses found in elk were elk-specific gamma-herpesviruses unrelated to cattle viruses. Pestivirus exposure in elk could not be ascertained to be of livestock origin. Evidence of MAP circulation was found in both elk and cattle, but there was no statistical effect of the species commingling. Finally, N. caninum was more frequently detected in elk exposed to cattle and this association was still significant after adjustment for herd and sampling year clustering, and individual elk age and sex. Only indirectly transmitted pathogens co-occurred in cattle and elk, indicating the potential importance of the transmission route in assessing the risk of pathogen transmission in multi-species grazing systems.     

Diversity of avipoxviruses in captive-bred Houbara bustard

Implementation of conservation breeding programs is a key step to ensuring the sustainability of many endangered species. Infectious diseases can be serious threats for the success of such initiatives especially since knowledge on pathogens affecting those species is usually scarce. Houbara bustard species (Chlamydotis undulata and Chlamydotis macqueenii), whose populations have declined over the last decades, have been captive-bred for conservation purposes for more than 15 years. Avipoxviruses are of the highest concern for these species in captivity. Pox lesions were collected from breeding projects in North Africa, the Middle East and Central Asia for 6 years in order to study the diversity of avipoxviruses responsible for clinical infections in Houbara bustard. Molecular and phylogenetic analyses of 113 and 75 DNA sequences for P4b and fpv140 loci respectively, revealed an unexpected wide diversity of viruses affecting Houbara bustard even at a project scale: 17 genotypes equally distributed between fowlpox virus-like and canarypox virus-like have been identified in the present study. This suggests multiple and repeated introductions of virus and questions host specificity and control strategy of avipoxviruses. We also show that the observed high virus burden and co-evolution of diverse avipoxvirus strains at endemic levels may be responsible for the emergence of novel recombinant strains.     

Characterization of commercial carrageenans by Fourier transform infrared spectroscopy using single-reflection attenuated total reflection

The purity and composition of commercial carrageenans vary widely and, therefore, have to be checked prior to their use in the food industry. Infrared spectroscopy is an alternative method to the expensive and time-consuming wet chemical and NMR methods to characterize carrageenan samples. The use of an attenuated total reflection accessory coupled to a Fourier transform infrared spectrophotometer allows a direct analysis of the sample without any preparation step, which is an additional benefit for the rapid identification check of raw material at reception in an industrial environment. Using a set of calibration samples, three multivariate calibrations were developed to predict the total carrageenan content as well as the molar ratio of kappa- and iota-carrageenans. A validation with an independent set of samples confirmed the robustness of the calibrations and the accuracy of the predictions. The accuracies of the calibrations given by their respective standard errors of prediction are 5.6 g/100 g, and 6.1 mol %, and 6.6 mol %, respectively, for the total carrageenan content and the molar ratios of kappa- and iota-carrageenans. The total preparation and analysis time is <5 min per sample.     

Effect of passage of a Potato virus Y isolate on a line of tobacco containing the recessive resistance gene va2 on the development of isolates capable of overcoming alleles 0 and 2

Control strategies developed for plant viral diseases through breeding programs can be impaired by adaptive response of pathogens. A few years after the deployment in France of improved tobacco genotypes introgressed with alleles of the Potato virus Y (PVY) recessive resistance gene va, necrotic symptoms associated with PVY infection have been reported on these cultivars. Due to the lack of efficient alternative methods to control PVY, the va resistance sources have to be managed according to viral parameters, such as the dynamic of emergence of virulent variants. The effects of va alleles on the evolution of PVY was tested in experimental conditions using a PVY infectious clone and two couples of resistant tobacco near isogenic lines BVA/Bva ⁰ and FVA/Fva ² both allelic for the va gene. Infection efficiencies data showed that a single passage on Fva ² line led to the selection of virulent viral populations able to overcome both va ⁰ and va ² alleles. Sequence analyses of va ² derived PVY variants revealed that the acquisition of the capacity to overcome va ² resistance is associated with single point mutations at two different nucleotide positions in the central part of the VPg. The described PVY adaptation process to overcome resistance mediated by different va alleles should be considered for the future development of durable and integrated strategies of management of PVY infections in tobacco crops.     

A conserved mutation in an ethylene biosynthesis enzyme leads to andromonoecy in melons

Andromonoecy is a widespread sexual system in angiosperms characterized by plants carrying both male and bisexual flowers. In melon, this sexual form is controlled by the identity of the alleles at the andromonoecious (a) locus. Cloning of the a gene reveals that andromonoecy results from a mutation in the active site of 1-aminocyclopropane-1-carboxylic acid synthase. Expression of the active enzyme inhibits the development of the male organs and is not required for carpel development. A causal single-nucleotide polymorphism associated with andromonoecy was identified, which suggests that the a allele has been under recent positive selection and may be linked to the evolution of this sexual system.     

An in planta, Agrobacterium-mediated transient gene expression method for inducing gene silencing in rice (Oryza sativa L.) leaves

Background

Although the genetic structure of rice germplasm has been characterized worldwide, few studies investigated germplasm from Thailand, the world’s largest exporter of rice. Thailand and the International Rice Research Institute (IRRI) have diverse collections of rice germplasm, which could be used to develop breeding lines with desirable traits. This study aimed to investigate the level of genetic diversity and structures of Thai and selected IRRI germplasm. Understanding the genetic structure and relationships among these germplasm will be useful for parent selection used in rice breeding programs.

Results

From the 98 InDel markers tested for single copy and polymorphism, 19 markers were used to evaluate 43 Thai and 57 IRRI germplasm, including improved cultivars, breeding lines, landraces, and 5 other Oryza species. The Thai accessions were selected from all rice ecologies such as irrigated, deep water, upland, and rainfed lowland ecosystems. The IRRI accessions were groups of germplasm having agronomic desirable traits, including temperature-sensitive genetic male sterility (TGMS), new plant type, early flowering, and biotic and abiotic stress resistances. Most of the InDel markers were genes with diverse functions. These markers produced the total of 127 alleles for all loci, with a mean of 6.68 alleles per locus, and a mean Polymorphic Information Content (PIC) of 0.440. Genetic diversity of Thai rice were 0.3665, 0.4479 and 0.3972 for improved cultivars, breeding lines, and landraces, respectively, while genetic diversity of IRRI improved and breeding lines were 0.3272 and 0.2970, respectively. Cluster, structure, and differentiation analyses showed six distinct groups: japonica, TGMS, deep-water, IRRI germplasm, Thai landraces and breeding lines, and other Oryza species.

Conclusions

Thai and IRRI germplasm were significantly different. Thus, they can be used to broaden the genetic base and trait improvements. Cluster, structure, and differentiation analyses showed concordant results having six distinct groups, in agreement with their development, and ecologies.     

The effect of the DNA preparation method on the sensitivity of PCR for the detection of Trypanosoma evansi in rodents and implications for epidemiological surveillance efforts

Trypanosoma evansi is responsible for the most largely distributed animal trypanosomosis, affecting a wide range of wild and domestic animals. Its surveillance requires the implementation of standardized and reliable diagnostic tools. Although the development of polymerase chain reaction (PCR) tools has greatly improved our diagnostic capacity, factors affecting their sensitivity need to be acknowledged and accounted for in the interpretation of results. The targeted gene and the primer design have already been shown to greatly affect the sensitivity of a PCR, and the best-performing sets of primers have been previously identified. However, the sensitivity of the PCR is also largely influenced by the DNA extraction or sample preparation method. In this paper, we selected 6 DNA extraction or blood sample preparation methods representative of what would be used in a budget-constrained setting: phenol–chloroform, Chelex^®, Flexigen (Qiagen^®) kit, Genekam^® kit and two original protocols using sodium hydroxide. We studied the effects of the preparation method on the detection limit of the subsequent PCR. Our results show that the extraction method strongly affects the PCR sensitivity. The classical phenol–chloroform extraction method allowed for the PCR with the lowest detection limit. Some combinations of extraction method and primer set had detection limits that were not compatible with their use as a reliable diagnostic test, and would severely reduce the performance of a surveillance program. Therefore, we encourage laboratories to carefully select their sample preparation and PCR protocols, depending on the aimed sensitivity, cost, safety, time requirement and objectives.