Spatial variability of 2,4-dichlorophenoxyacetic acid (2,4-D) mineralisation potential at a millimetre scale in soil

We analysed the ability of soil units of millimetre size to mineralise a herbicide, 2,4-D, using incubations of individual aggregates (2-7 mm diameter) and 6×6×6 mm³ cubes dissected from soil cores, under standard conditions. Mineralisation of ¹⁴C-ring labelled 2,4-D was measured using a barite paper trap and a Phosphorimager to record the evolved ¹⁴C-CO₂ from these very small soil samples. We found a large variability of 2,4-D mineralisation potential between aggregate size classes, between individual aggregates of the same size and between the different dissected cubes from a given core. We explained this variability by an uneven distribution of the degrading microorganisms at this scale, and to a lesser extent, an uneven distribution of C, necessary for co-metabolism. Furthermore, we found that in a soil core, the dissected cubes with a large mineralisation potential were not randomly distributed, but rather organised into centimetre sized hot spots.     

Defective telomere lagging strand synthesis in cells lacking WRN helicase activity

Cells from Werner syndrome patients are characterized by slow growth rates, premature senescence, accelerated telomere shortening rates, and genome instability. The syndrome is caused by the loss of the RecQ helicase WRN, but the underlying molecular mechanism is unclear. Here we report that cells lacking WRN exhibit deletion of telomeres from single sister chromatids. Only telomeres replicated by lagging strand synthesis were affected, and prevention of loss of individual telomeres was dependent on the helicase activity of WRN. Telomere loss could be counteracted by telomerase activity. We propose that WRN is necessary for efficient replication of G-rich telomeric DNA, preventing telomere dysfunction and consequent genomic instability.     

Legumes symbioses: absence of Nod genes in photosynthetic bradyrhizobia

Leguminous plants (such as peas and soybeans) and rhizobial soil bacteria are symbiotic partners that communicate through molecular signaling pathways, resulting in the formation of nodules on legume roots and occasionally stems that house nitrogen-fixing bacteria. Nodule formation has been assumed to be exclusively initiated by the binding of bacterial, host-specific lipochito-oligosaccharidic Nod factors, encoded by the nodABC genes, to kinase-like receptors of the plant. Here we show by complete genome sequencing of two symbiotic, photosynthetic, Bradyrhizobium strains, BTAi1 and ORS278, that canonical nodABC genes and typical lipochito-oligosaccharidic Nod factors are not required for symbiosis in some legumes. Mutational analyses indicated that these unique rhizobia use an alternative pathway to initiate symbioses, where a purine derivative may play a key role in triggering nodule formation.     

Educated consumers don’t believe artiifcial meat is the solution to the problems with the meat industry

The production of in vitro meat by cel culture has been suggested by some scientists as one solution to address the major chal enges facing our society. Firstly, consumers would like the meat industry ...     

Aggregation and availability of phosphorus in a Technosol constructed from urban wastes

Purpose

To preserve natural soil resources and in order to create fertile constructed Technosols for plant cultivation, wastes and by-product mixtures were studied in relation to their pedogenic properties and especially soil organic matter contents. We assessed interactions between aggregation and nutrient availability, focusing on phosphorus (P) transfer in the soil-water-plant system.

Materials and methods

Four typical urban wastes, dried and sieved to pass 2 mm, were mixed selectively to mimic a fertile topsoil material: excavated subsoil AE, compost from sludge and green wastes CO, green wastes GW, and bricks BR. After characterization of the wastes for physico-chemical and toxicological parameters, we focused on four mixtures: AE/CO, AE/GW, BR/CO, and BR/GW. The mixtures were tested in a 55-day long pot experiment under controlled conditions in a climate chamber. Pots were bare and planted with Lolium perenne (ryegrass) and Brassica napus (rape). The two plant species were selected for contrasting root activities and architectures and phosphorus (P) acquisition strategies. The aggregate formation was tested using the mean weight diameter method at the end of the experiment.

Results and discussion

We have measured intense aggregation in mixture AE/GW, low aggregation in AE/CO, and no aggregation in BR/CO and BR/GW. After 55 days, neither Technosol aggregation nor aggregate stability was significantly affected by plant development. Available phosphorus (P_Olsen) content was sufficient for plant development in all the mixtures (from 0.28 to 0.58 g kg^?1). The P_Olsen/P_total ratio was higher in mixtures with GW, even if the mixtures with compost (AE/CO and BR/CO) induced the highest biomass production for ryegrass and rape.

Conclusions

The nutrient availability in constructed Technosols and the transfer of P to plant were highly dependent on organic matter type, with high or low delivery of P_Olsen linked to the mineralization potential and the size and distribution of aggregates. Therefore, pedological engineering processes can be improved by the selection of adapted constitutive wastes and by-products to create a fertile substrate allowing high biomass production.

     

DEVELOPING A TECHNIQUE FOR ULTRASOUND‐GUIDED INJECTION OF THE ADULT CANINE HIP

An accurate method for guiding injections into the canine hip would facilitate diagnostic localization of lameness and targeted treatments. Ultrasound‐guided hip injections are commonly used in humans and large animals. Aims of this prospective study were to describe ultrasound (US) anatomy of the adult canine hip and determine the feasibility and accuracy of intra‐articular placement of injectate using US‐guidance. Seven adult dogs were used to describe US anatomy, five dog cadavers were used to assess the feasibility of the injection technique and 11 dog cadavers were used to assess accuracy of injections. For the accuracy test, 22 joints were injected with iodinated contrast medium by three operators with different experience. With dogs in lateral recumbency, the hyperechoic femoral head surface was identified by following the femoral neck from the greater trochanter or the acetabular rim was localized by following caudally the ilium from the iliac wing.  An anechoic gap between the femoral head and acetabular surface represented the joint. The capsule was visible as a triangular echoic structure and the femoral head articular cartilage appeared as an anechoic band. The needle was inserted axial to the greater trochanter and directed in a dorsolateral–ventromedial direction toward the joint space and then pushed through the capsule. Based on postinjection radiography, accuracy was 81.8% at first attempt and 100% at second attempt. This study indicated that US‐guided injection is a feasible and accurate technique for injecting the adult canine hip. Future studies in live dogs are needed to assess safety and efficacy.     

Bacterial injectisomes: needle length does matter

Many pathogenic bacteria use a type III secretion nanomachine (an injectisome) to deliver virulence proteins into the cytosol of their eukaryotic host cells. Most injectisomes possess a stiff needlelike structure of a genetically defined length. We found that a minimal needle length was required for efficient functioning of the Yersinia enterocolitica injectisome. This minimal needle length correlated with the length of the major adhesin at the bacterial surface. The needle may be required for triggering type III secretion, and its length may have evolved to match specific structures at the bacterial and host cell surfaces.     

Plasma N-terminal pro-B-type natriuretic peptide concentration helps to predict survival in dogs with symptomatic degenerative mitral valve disease regardless of and in combination with the initial clinical status at admission

Objectives

Although mitral valve disease (MVD) is the most common canine heart disease, readily available prognostic markers of the disease are still lacking. The aim of this study was to evaluate the comparative ability of N-terminal pro-B-type natriuretic peptide plasma concentration (NT-proBNP) and various echocardiographic variables to predict outcome in dogs with MVD.

Animals, materials and methods

Seventy-four dogs with ISACHC classes 2 and 3 MVD (Groups A and B, respectively) were prospectively recruited. NT-proBNP and several echo-Doppler variables at inclusion were compared as predictors of outcome at 6 months in 54/74 dogs.

Results

NT-proBNP was significantly higher in Group B than in Group A (P < 0.0001), and was the only tested variable significantly different between survivor and non-survivor dogs in both groups (P < 0.05). In the whole canine population, a threshold of 1500 pmol/L could discriminate survivor from non-survivor dogs with a sensitivity and specificity of 80% and 73%, respectively. When combining ISACHC class with NT-proBNP levels, a cut-off of 1265 pmol/L was predictive of survival in Group A, whereas the cut-off was 2700 pmol/L for Group B.

Conclusions

NT-proBNP is correlated with MVD severity and could be used in combination with clinical status to predict cardiac outcome.     

Microalgal Dynamics in Batch Reactors for Municipal Wastewater Treatment Containing Dairy Sewage Water

This study investigates the microalgal community dynamics associated with changes in municipal wastewater quality and discharges from the dairy industry in central Veracruz, Mexico, using an experimental stabilization-reactors system. Thirty one species of microalgae were recorded and 15 physicochemical variables were measured daily over 25 days in pretreated water. The biomass of microalgal groups displayed significant negative correlations with biochemical oxygen demand (BOD), chemical oxygen demand (COD) and total suspend solids (TSS). Conversely, a significant positive correlation was found with dissolved oxygen, pH and nitrates. Using the Canonical Correspondence Analysis we identified an initial anaerobic phase (Phase I), characterized by high BOD, TSS and COD, ammonium and faecal coliforms. This was followed by a transition phase (Phase II), an initial aerobic phase (Phase III), when water quality improved considerably, and finally an aerobic phase (IV) with a high percent reduction in these parameters and almost complete organic load removal. The most abundant species associated with these phases were Arthrospira jenneri (Cyanophyceae) and Coccomonas sp. (Chlorophyceae) in Phase I; Polytomella sp. (Chlorophyceae) in Phase II; Polytoma tetraolare, Chlamydomonas caeca (Chlorophyceae) and some Cyanophyceae including Geitlerinema, Synechocystis, Cyanobium and Glaucospira in Phase III; Carteria sp. (Chlorophyceae), Lepocynclis ovum and Euglena clavata (Euglenophcyeae) in Phase IV. Maximum richness, diversity, and biomass levels occurred during the aerobic phase. Similar to other wastewater treatment systems the high succession rates decreased with reactor stabilization. These findings provide statistical evidence on the suitability of certain microalgae species as indicators of wastewater stabilization reactor status and effluent quality.