High quantitative and no molecular differentiation of a freshwater snail (Galba truncatula) between temporary and permanent water habitats.

We investigate the variation in quantitative and molecular traits in the freshwater snail Galba truncatula, from permanent and temporary water habitats. Using a common garden experiment, we measured 20 quantitative traits and molecular variation using seven microsatellites in 17 populations belonging to these two habitats. We estimated trait means in each habitat. We also estimated the distributions of overall genetic quantitative variation (QST), and of molecular variation (FST), within and between habitats. Overall, we observed a lack of association between molecular and quantitative variance. Among habitats, we found QST>FST, an indication of selection for different optima. Individuals from temporary water habitat matured older, at a larger size and were less fecund than individuals from permanent water habitat. We discuss these findings in the light of several theories for life-history traits evolution.

A new green fluorescent protein-based bacterial biosensor for analysing phenanthrene fluxes.

The polycyclic aromatic hydrocarbon (PAH)-degrading strain Burkholderia sp. RP007 served as host strain for the design of a bacterial biosensor for the detection of phenanthrene. RP007 was transformed with a reporter plasmid containing a transcriptional fusion between the phnS putative promoter/operator region and the gene encoding the enhanced green fluorescent protein (GFP). The resulting bacterial biosensor--Burkholderia sp. strain RP037--produced significant amounts of GFP after batch incubation in the presence of phenanthrene crystals. Co-incubation with acetate did not disturb the phenanthrene-specific response but resulted in a homogenously responding population of cells. Active metabolism was required for induction with phenanthrene. The magnitude of GFP induction was influenced by physical parameters affecting the phenanthrene flux to the cells, such as the contact surface area between solid phenanthrene and the aqueous phase, addition of surfactant, and slow phenanthrene release from Model Polymer Release System beads or from a water-immiscible oil. These results strongly suggest that the bacterial biosensor can sense different phenanthrene fluxes while maintaining phenanthrene metabolism, thus acting as a genuine sensor for phenanthrene bioavailability. A relationship between GFP production and phenanthrene mass transfer is proposed.

First detection of Waddlia chondrophila in Africa using SYBR Green real-time PCR on veterinary samples.

Waddlia chondrophila is a strict intracellular microorganism belonging to the order Chlamydiales that has been isolated twice from aborted bovine fetuses, once in USA and once in Germany. This bacterium is now considered as an abortigenic agent in cattle. However, no information is available regarding the presence of this bacterium in Africa. Given the low sensitivity of cell culture to recover such an obligate intracellular bacterium, molecular-based diagnostic approaches are warranted. This report describes the development of a quantitative SYBR Green real-time PCR assay targeting the recA gene of W. chondrophila. Analytical sensitivity was 10 copies of control plasmid DNA per reaction. No cross-amplification was observed when testing pathogens that can cause abortion in cattle. The PCR exhibited a good intra-run and inter-run reproducibility. This real-time PCR was then applied to 150 vaginal swabs taken from Tunisian cows that have aborted. Twelve samples revealed to be Waddlia positive, suggesting a possible role of this bacterium in this setting. This new real-time PCR assay represents a diagnostic tool that may be used to further study the prevalence of Waddlia infection.

Ultrastructural changes of the internal limiting membrane removed during indocyanine green assisted peeling versus conventional surgery for an idiopathic epimacular membrane

Purpose:To evaluate the histological features of cellular retinal fragments on the internal limiting membrane (ILM) removed during epiretinal membrane peeling surgery with and without the aid of ICG diluted in 5% glucose Methods:ILM specimens removed from 88 eyes undergoing vitrectomy and membrane peeling surgery for idiopathic epiretinal membrane between 1995 and 2003 were reviewed retrospectively. Surgery was performed in all cases by the same surgeon using the same technique. ICG was diluted with 5% glucose. Histological analysis focused on the presence and characteristics of retinal structures on the retinal surface of the ILM. Statistical analysis compared the results between group I (conventional surgery without ICG) and group II (ICG-assisted peeling) Results:Seventy-one eyes underwent EMM surgery without the aid of ICG (group I) and seventeen underwent EMM ICG-assisted surgery assisted using ICG (group II). The amount of Muller cell debris on the retinal surface of the ILM was more significant in the group I (no ICG) than in the group II (ICG) (40.8 versus 11.8; p = 0.024). Large fragments of Muller cells were more frequently observed in the group I (no ICG) than in the group II (ICG) (63.4% versus 23.5%; p= 0.003).The presence of larger retinal elements such as neural axons and vessels were observed attached to retinal face of the ILM in 5 (7%) cases of the no-ICG group. No such retinal elements were detected in any of the histological ILM specimens of the ICG-assisted group Conclusions:The use of ICG diluted with 5% glucose in the aid of ILM removal during epiretinal membrane surgery was associated with less retinal debris attached to retinal face of the ILM compared to surgery in which ICG was not used. Our findings contradict previous reports in the literature, in which use of ICG diluted with balanced salt solution (BSS) was associated with more retinal fragments attached to the retinal face of the ILM. According to our results, we hypothesize that diluting ICG with 5% glucose may decrease the adhesion of the ILM to the underlying retinal layers such that less retinal debris is removed with peeling of the ILM.

Green manure incorporation timing for organically grown broccoli

The objective of this work was to determine the effect of incorporation timing of the velvet bean (Stizolobium cinereum) (GM) on both organic broccoli yield and N status. Mineral N content in the soil, biologically fixed N recovery by broccoli, GM biomass decomposition and N release kinetics were also determined. Plots were fertilized with 12 Mg ha-1 of organic compost and received GM either at 0, 15, 30 or 45 days after transplant. Other treatments were compost (12 or 25 Mg ha-1), GM, mineral fertilizers and control (no fertilizer). The data were collected in four completely randomized blocks. GM decomposition increased mineral N content in soil as rapidly as mineral fertilizer or the supply of 25 Mg ha-1 of compost. The N half-life in GM (24 days) is smaller than the mass half-life (35 days) and the biological fixation contributed with 23.6% of N present in the aboveground biomass of broccoli. The result suggests a higher synchrony between the crop relative growth rate and N release from the GM when incorporated at crop early growth stage. The incorporation of GM until 15 days after transplanting replaces 50% of the highest compost dose, without yield loss.

Recovery of a persistent Canine distemper virus expressing the enhanced green fluorescent protein from cloned cDNA.

Wild-type A75/17-Canine distemper virus (CDV) is a highly virulent strain, which induces a persistent infection in the central nervous system (CNS) with demyelinating disease. Wild-type A75/17-CDV, which is unable to replicate in cell lines to detectable levels, was adapted to grow in Vero cells and was designated A75/17-V. Sequence comparison between the two genomes revealed seven nucleotide differences located in the phosphoprotein (P), the matrix (M) and the large (L) genes. The P gene is polycistronic and encodes two auxiliary proteins, V and C, besides the P protein. The mutations resulted in amino acid changes in the P and V, but not in the C protein, as well as in the M and L proteins. Here, a rescue system was developed for the A75/17-V strain, which was shown to be attenuated in vivo, but retains a persistent infection phenotype in Vero cells. In order to track the recombinant virus, an additional transcription unit coding for the enhanced green fluorescent protein (eGFP) was inserted at the 3' proximal position in the A75/17-V cDNA clone. Reverse genetics technology will allow us to characterize the genetic determinants of A75/17-V CDV persistent infection in cell culture.

Phosphorus utilization by corn as affected by green manure, nitrogen and phosphorus fertilizers

The objective of this work was to evaluate the utilization by corn plants of P from triple superphosphate fertilizer labeled with 32P (32P‑TSP), and of P from soil as affected by N rates and by the green manures (GM) sunn hemp (Crotalaria juncea) and millet (Pennisetum glaucum). The experiment was carried out using pots filled with 5 kg Oxisol (Rhodic Hapludox). A completely randomized design was used, in a 4x4x2 factorial arrangement, with four replicates. The treatments were: four P rates as TSP (0, 0.175, 0.350, and 0.700 g P per pot); four N rates as urea (0, 0.75, 1.50, and 2.25 g N per pot); and sunn hemp or millet as green manure. The additions of N and P by the GM were taken into account. After grain physiologic maturation, corn dry matter, P contents, accumulated P, and P recovery in the different treatments were measured. 32P‑TSP recovery by corn increased with N increasing rates, and decreased with increasing rates of 32P‑TSP. The mineral fertilizer provides most of the accumulated P by corn plants. The recovery of 32P‑TSP by corn was 13.12% in average. The green manure species influence the assimilation of 32P‑TSP by the plants.

Desempenho per se e parâmetros genéticos de linhagens de trigo com expressão do caráter "stay‑green"

O objetivo deste trabalho foi determinar o desempenho per se e os parâmetros genéticos de caracteres de interesse, em linhagens de trigo que expressam ou não o caráter "stay‑green". O experimento foi conduzido em 2003, 2004 e 2005, em delineamento experimental de blocos ao acaso, com três repetições. Foram avaliadas 32 linhagens irmãs de trigo, 15 com e 17 sem o caráter "stay‑green". As linhagens portadoras desse caráter apresentaram maior produtividade de grãos, maior número de grãos por espiga e menor massa de mil grãos. Além disso, as herdabilidades da produtividade e da massa de grãos foram maiores nessas linhagens, o que revelou menor influência de variações ambientais sobre a expressão desses caracteres. O caráter "stay‑green" contribui para o aumento da produtividade e da estabilidade produtiva do trigo.

Toxicity of triclosan, penconazole and metalaxyl on Caulobacter crescentus and a freshwater microbial community as assessed by flow cytometry.

Biocides are widely used for domestic hygiene, agricultural and industrial applications. Their widespread use has resulted in their introduction into the environment and raised concerns about potential deleterious effects on aquatic ecosystems. In this study, the toxicity of the biocides triclosan, penconazole and metalaxyl were evaluated with the freshwater bacterium Caulobacter crescentus and with a freshwater microbial community using a combination of single- and double-stain flow cytometric assays. Growth of C.  crescentus and the freshwater community were repressed by triclosan but not by penconazole or metalaxyl at concentrations up to 250 μM. The repressive effect of triclosan was dependent on culture conditions. Caulobacter crescentus was more sensitive to triclosan when grown with high glucose at high cell density than when grown directly in sterilized lake water at low cell density. This suggests that the use of conventional growth conditions may overestimate biocide toxicity. Additional experiments showed that the freshwater community was more sensitive to triclosan than C.  crescentus, with 10 nM of triclosan being sufficient to repress growth and change the phylogenetic composition of the community. These results demonstrate that isolate-based assays may underestimate biocide toxicity and highlight the importance of assessing toxicity directly on natural microbial communities. Because 10 nM of triclosan is within the range of concentrations observed in freshwater systems, these results also raise concerns about the risk of introducing triclosan into the environment.

Chemical composition and fatty acid contents in farmed freshwater prawns

The objective of this work was to evaluate the chemical composition and fatty acid contents of Amazonian and giant river prawns. After four-month farming, with the same diet for both species, palmitic and stearic acids were the main saturated fatty acids. Oleic acid was the main monounsatured fatty acid, and the eicosapentaenoic and docosahexaenoic acids were the most abundant polyunsaturated acids. Amazonian prawn has higher levels of protein and polyunsaturated fatty acids than those of the giant river prawn, which shows its potential for aquaculture.