Effect of soil conditions and landscape factors on macro-snail communities in newly created grasslands of restored landfill sites in the UK

Though restored landfill sites provide habitat for a number of taxa, their potential for land snail remains unexplored. In this study, large-sized land snails (> 5 mm) were surveyed using transect sampling on nine restored landfill sites and nine corresponding nature sites in the East Midlands region of the UK during 2008. The effect of restoration was investigated by examining land snail species composition, richness, and diversity (Shannon Weiner index) in relation to habitat and landscape structure. Thirteen macro-snail species were found in total and rarefied species richness and diversity on restored landfill sites was not found to be statistically different to that of reference sites. One third of the snail species, comprising 30% of total abundance, found in the restored landfill sites were non-native species introduced to the UK. Soil electrical conductivity was the strongest predictor for richness and diversity of land snails. Road density was found to have a positive influence on snail species diversity. Given the high percentage of introduced species detected further research is needed in terms of the management implications of restored landfill sites and the dynamics of native versus non-native species

The distribution of pond snail communities across a landscape: separating out the influence of spatial position from local habitat quality for ponds in south-east Northumberland, UK

Ponds support a rich biodiversity because the heterogeneity of individual ponds creates, at the landscape scale, a diversity of habitats for wildlife. The distribution of pond animals and plants will be influenced by both the local conditions within a pond and the spatial distribution of ponds across the landscape. Separating out the local from the spatial is difficult because the two are often linked. Pond snails are likely to be affected by both local conditions, e.g. water hardness, and spatial patterns, e.g. distance between ponds, but studies of snail communities struggle distinguishing between the two. In this study, communities of snails were recorded from 52 ponds in a biogeographically coherent landscape in north-east England. The distribution of snail communities was compared to local environments characterised by the macrophyte communities within each pond and to the spatial pattern of ponds throughout the landscape. Mantel tests were used to partial out the local versus the landscape respective influences. Snail communities became more similar in ponds that were closer together and in ponds with similar macrophyte communities as both the local and the landscape scale were important for this group of animals. Data were collected from several types of ponds, including those created on nature reserves specifically for wildlife, old field ponds (at least 150 years old) primarily created for watering livestock and subsidence ponds outside protected areas or amongst coastal dunes. No one pond type supported all the species. Larger, deeper ponds on nature reserves had the highest numbers of species within individual ponds but shallow, temporary sites on farm land supported a distinct temporary water fauna. The conservation of pond snails in this region requires a diversity of pond types rather than one idealised type and ponds scattered throughout the area at a variety of sites, not just concentrated on nature reserves

Electrochemical recovery of zinc from the spent pickling baths coming from the hot dip galvanizing industry. Potentiostatic operation

An electrochemical reactor was developed to recover zinc from the spent pickling solutions coming from the hot dip galvanizing industry. These solutions mainly contain ZnCl2 and FeCl2 in aqueous HCl media. The effect of the applied potential on the figures of merit (fractional conversion, current efficiency, space-time yield and specific energy consumption) of the electrochemical reactor was analysed. Voltammetric experiments were performed previously in order to select the optimum conditions to be applied in the electrolysis experiments. From the I-V curves it was inferred that bulk zinc deposition started from potential values more cathodic than -0.99 V. The hydrogen evolution reaction (HER) appeared from -0.45 V and masked the zinc cathodic peak C1, related to bulk zinc deposition, at high HCl concentrations. The presence of HCl inhibited iron deposition in synthetic samples. The additives present in the real baths, which diminish the massive hydrogen generation, allowed the observation of peak C1. The potential values to be applied in the electrolysis experiments were chosen from the voltammetric experiments and ranged between -1 V and -1.75 V. In the absence of iron in solution, as the electrode potential was shifted towards more negative values, the space-time yield of zinc and its fractional conversion increased because of the increase in the electrode roughness and the hydrogen turbulence-promoting action. Simultaneously, the specific energy consumption decreased initially due to the increase in the zinc conversion rate but decreased for the most cathodic potential value due to HER. The presence of iron in synthetic solutions led to a decrease in current efficiency associated with the reverse redox Fe 2+/Fe3+ system and to the enhancement of the HER, which also induced increments in the local pH and the subsequent zinc redissolution for the most cathodic potential values. On the contrary, the additives present in the real spent pickling baths avoided the adverse effects of iron, and zinc electrodeposition was possible even at high cathodic potential values. In fact, a potential value of -1.75 V was selected as the optimum since the conversion, the current efficiency and the space time yield obtained in the real baths were relatively high.Authors want to express their gratitude to the Universidad Politecnica de Valencia for the economical support in the project reference PAID-06-08, and to the Generalitat Valenciana for the financing of the project reference GV/2010/029.Carrillo Abad, J.; García Gabaldón, M.; Ortega Navarro, EM.; Pérez-Herranz, V. (2011). Electrochemical recovery of zinc from the spent pickling baths coming from the hot dip galvanizing industry. Potentiostatic operation. Separation and Purification Technology. 81(2):200-207. https://doi.org/10.1016/j.seppur.2011.07.029S20020781

Recovery of zinc from spent pickling solutions using an electrochemical reactor in presence and absence of an anion-exchange membrane: Galvanostatic operation

The performance of a one- and two-compartment electrochemical reactor under galvanostatic control for zinc recovery present in the spent pickling solutions is studied in this paper. These solutions, which mainly contain ZnCl 2 and FeCl 2 in aqueous HCl media, come from the hot dip galvanizing industry. The effect of the anion-exchange membrane (AEM) on the figures of merit of the electrochemical reactor is analyzed. In the absence of iron in solution, as the current value was shifted towards more negative values, the zinc fractional conversion increased because of the increase in the zinc reduction rate. However, the increase in current values made current efficiency decrease due to the hydrogen-reduction side reaction, which caused an increment in the specific energy consumption. The presence of iron in synthetic solutions led to a decrease in current efficiency associated with the reverse redox Fe 2+/Fe 3+ system and to the enhancement of the HER, which also induced increments in the local pH and the subsequent zinc redissolution. These adverse effects related to the presence of iron could be minimized by the interposition of an AEM. In this case, the zinc redissolution was eliminated which enabled zinc conversion values close to 100% together with higher current efficiencies as the consumption of current by the system Fe 2+/Fe 3+ was diminished. © 2012 Elsevier B.V. All rights reserved.Authors want to express their gratitude to the Universidad Politecnica de Valencia for the economic support in the Project Reference PAID-06-08, and to the Generalitat Valenciana for the financing of the Project Reference GV/2010/029.Carrillo Abad, J.; García Gabaldón, M.; Ortega Navarro, EM.; Pérez-Herranz, V. (2012). Recovery of zinc from spent pickling solutions using an electrochemical reactor in presence and absence of an anion-exchange membrane: Galvanostatic operation. Separation and Purification Technology. 98:366-374. https://doi.org/10.1016/j.seppur.2012.08.006S3663749

Treatment of spent pickling baths coming from hot dip galvanizing by means of an electrochemical membrane reactor

The performance of a one (OCR) and a two-compartment electrochemical reactor in the presence of a cation-exchange membrane (CEM) for the zinc recovery present in the spent pickling baths is analyzed in this paper under galvanostatic control. These solutions, which mainly contain ZnCl2 and FeCl2 in aqueous HCl media, come from the hot dip galvanizing industry. The effect of the applied current, the dilution factor of the baths and the presence or absence of initial cathodic zinc is also studied. For the 1:50 diluted spent bath, OCR experiments initially present higher values of the figures of merit than those obtained in the presence of the CEM since zinc is close to the cathode from the first electrolysis instants. However, at long electrolysis times, OCR presents zinc redissolution for all the current values tested due to the chlorine and iron presence close to the zinc deposits. In addition, the iron codeposition phenomenon is also observed in the OCR experiments when pH values are close to 2. On the other hand, CEM experiments become very similar to the OCR experiments at long time values since the CEM under these experimental conditions prevents zinc redissolution phenomenon and also iron codeposition. When the 1:50 diluted bath is concentred to 1:10, OCR experiments present the same tendency as that observed for the 1:50 dilution factor but the effect of zinc redissolution is increased due to the greater amount of chlorine generated in the anode. Under these experimental conditions, iron deposition has also been observed in the presence of the cation-exchange membrane as the rate of zinc deposition is greater than that of zinc transport through the membrane, and the zinc/iron ratio in the cathodic compartment is not high enough to prevent iron codeposition. In both cases, the pH values when iron codeposits with zinc are close to 2 and the zinc/iron ratio is below 0.6. The presence of initial zinc in the cathodic compartment of the electrochemical reactor enhances the reactor performance since it allows the zinc–iron separation in one single step and avoids the zinc redissolution phenomenon.The authors want to express their gratitude to the Generalitat Valenciana for a postgraduate grant (GV/2010/029) and to the Ministerio de Economia y Competitividad for financing the project number CTQ2012-37450-C02-01/PPQ.Carrillo Abad, J.; García Gabaldón, M.; Pérez Herranz, V. (2014). Treatment of spent pickling baths coming from hot dip galvanizing by means of an electrochemical membrane reactor. Desalination. 343:38-47. https://doi.org/10.1016/j.desal.2013.11.040S384734

An orphan gene is necessary for preaxial digit formation during salamander limb development

Limb development in salamanders differs from other tetrapods in that the first digits to form are the two most anterior (preaxial dominance). This has been proposed as a salamander novelty and its mechanistic basis is unknown. Salamanders are the only adult tetrapods able to regenerate the limb, and the contribution of preaxial dominance to limb regeneration is unclear. Here we show that during early outgrowth of the limb bud, a small cohort of cells express the orphan gene Prod1 together with Bmp2, a critical player in digit condensation in amniotes. Disruption of Prod1 with a gene-editing nuclease abrogates these cells, and blocks formation of the radius and ulna, and outgrowth of the anterior digits. Preaxial dominance is a notable feature of limb regeneration in the larval newt, but this changes abruptly after metamorphosis so that the formation of anterior and posterior digits occurs together within the autopodium resembling an amniote-like pattern

Towards a Synthetic Chloroplast

The evolution of eukaryotic cells is widely agreed to have proceeded through a series of endosymbiotic events between larger cells and proteobacteria or cyanobacteria, leading to the formation of mitochondria or chloroplasts, respectively. Engineered endosymbiotic relationships between different species of cells are a valuable tool for synthetic biology, where engineered pathways based on two species could take advantage of the unique abilities of each mutualistic partner.We explored the possibility of using the photosynthetic bacterium Synechococcus elongatus PCC 7942 as a platform for studying evolutionary dynamics and for designing two-species synthetic biological systems. We observed that the cyanobacteria were relatively harmless to eukaryotic host cells compared to Escherichia coli when injected into the embryos of zebrafish, Danio rerio, or taken up by mammalian macrophages. In addition, when engineered with invasin from Yersinia pestis and listeriolysin O from Listeria monocytogenes, S. elongatus was able to invade cultured mammalian cells and divide inside macrophages.Our results show that it is possible to engineer photosynthetic bacteria to invade the cytoplasm of mammalian cells for further engineering and applications in synthetic biology. Engineered invasive but non-pathogenic or immunogenic photosynthetic bacteria have great potential as synthetic biological devices

Effect of cadmium on cytosine hydroxymethylation in gastropod hepatopancreas

5-Hydroxymethylcytosine (5hmC) is an important, yet poorly understood epigenetic DNA modification, especially in invertebrates. Aberrant genome-wide 5hmC levels have been associated with cadmium (Cd) exposure in humans, but such information is lacking for invertebrate bioindicators. Here, we aimed to determine whether this epigenetic mark is present in DNA of the hepatopancreas of the land snail Cantareus aspersus and is responsive to Cd exposure. Adult snails were reared under laboratory conditions and exposed to graded amounts of dietary cadmium for 14 days. Weight gain was used as a sublethal endpoint, whereas survival as a lethal endpoint. Our results are the first to provide evidence for the presence of 5hmC in DNA of terrestrial mollusks; 5hmC levels are generally low with the measured values falling below 0.03%. This is also the first study to investigate the interplay of Cd with DNA hydroxymethylation levels in a non-human animal study system. Cadmium retention in the hepatopancreas of C. aspersus increased from a dietary Cd dose of 1 milligram per kilogram dry weight (mg/kg d. wt). For the same treatment, we identified the only significant elevation in percentage of samples with detectable 5hmC levels despite the lack of significant mortalities and changes in weight gain among treatment groups. These findings indicate that 5hmC is an epigenetic mark that may be responsive to Cd exposure, thereby opening a new aspect to invertebrate environmental epigenetics