Degradation of 1,2,3,4-Tetrachlorobenzene by Pseudomonas chlororaphis RW71

Pseudomonas chlororaphis RW71 mineralized 1,2,3,4-tetrachlorobenzene, a highly recalcitrant pollutant hitherto not known to be degraded by pure cultures, as a sole source of carbon and energy, thereby releasing stoichiometric amounts of chloride. The transient excretion of tetrachlorocatechol in the early growth phase suggests an initial attack by a dioxygenase to form the corresponding dihydrodiol which rearomatizes to the catechol. The activity of chlorocatechol 1,2-dioxygenase in crude cell extracts was found to be extraordinarily high towards 3-chlorocatechol (ratio of 2.6 compared to catechol) and other chlorocatechols, including tetrachlorocatechol, which was transformed at a low but significant rate. Further identification of tetrachloromuconic acid, 2,3,5-trichlorodienelactone, 2,3,5-trichloromaleyl acetic acid, and 2,4-dichloro-3-oxoadipic acid as their methyl esters, together with high specific enzyme activities for chlorinated substrates, implicated a functioning chlorocatechol pathway to be induced during growth.     

The prion protein and neuronal zinc homeostasis

Although the prion protein (PrP) is known to be the causative agent of the neurodegenerative transmissible spongiform encephalopathies, its normal cellular function remains elusive. Octapeptide repeats in the N terminus of PrP bind metal ions and are required for the endocytosis of PrP upon exposure of cells to copper or zinc. As the concentration of zinc in the extracellular spaces of the brain is higher than that for copper, we put forward the hypothesis that PrP is involved in neuronal zinc homeostasis; PrP might be involved in transport of zinc into the cell or might act as a zinc sensor. In prion disease, when the protein undergoes a conformational change to the infectious form, this function of PrP in zinc homeostasis might be compromised.     

Global mapping of infectious disease

The primary aim of this review was to evaluate the state of knowledge of the geographical distribution of all infectious diseases of clinical significance to humans. A systematic review was conducted to enumerate cartographic progress, with respect to the data available for mapping and the methods currently applied. The results helped define the minimum information requirements for mapping infectious disease occurrence, and a quantitative framework for assessing the mapping opportunities for all infectious diseases. This revealed that of 355 infectious diseases identified, 174 (49%) have a strong rationale for mapping and of these only 7 (4%) had been comprehensively mapped. A variety of ambitions, such as the quantification of the global burden of infectious disease, international biosurveillance, assessing the likelihood of infectious disease outbreaks and exploring the propensity for infectious disease evolution and emergence, are limited by these omissions. An overview of the factors hindering progress in disease cartography is provided. It is argued that rapid improvement in the landscape of infectious diseases mapping can be made by embracing non-conventional data sources, automation of geo-positioning and mapping procedures enabled by machine learning and information technology, respectively, in addition to harnessing labour of the volunteer ‘cognitive surplus’ through crowdsourcing.     

Re-establishment of Calluna vulgaris (L.) Hull in an eight-year grazing experiment on upland acid grassland

Upland heathland is an internationally important habitat but a large area in the UK has been degraded to acid grassland by intensive livestock grazing. Re-establishment of dwarf shrubs, particularly Calluna vulgaris (L.) Hull, is a key objective for restoring heathland on these sites. A replicated plot-scale experiment was set up to examine effects of disturbance and seed addition on C. vulgaris establishment in a Nardus stricta L. grassland under three grazing regimes: sheep only (1.5 ewes ha^?1 for 10 months per year); cattle only (0.5 heifers ha^?1 in summer only); and, the cattle regime combined with sheep (1.0 ewes ha^?1 for 10 months per year). Early results of the experiment have been reported previously but it was not known if these results were an indication of the longer-term restoration success. Here we evaluate the success of the restoration methods (disturbance, seeding treatments and grazing regime) eight years after the treatments began. In seeded plots, young C. vulgaris plants had greatest above-ground height, dry weight and shoot length if grazing was excluded or the cattle-only regime was applied. C. vulgaris cover was greatest, and increased most, in plots that had been disturbed, seeded and ungrazed or subjected to the cattle-only regime. The vegetation in these plots also became more similar to reference sites with 50% or more cover of C. vulgaris. The invasive Juncus effusus L. was more frequent in disturbed and grazed plots but less frequent in plots with C. vulgaris established from added seed. Previous results that showed the benefits of disturbance and seeding treatments were still valid but changes in the vegetation composition were still occurring and longer-term studies will be needed to determine when grazing regimes including sheep might be reintroduced.     

Optical quantal analysis reveals a presynaptic component of LTP at hippocampal Schaffer-associational synapses

The mechanisms by which long-term potentiation (LTP) is expressed are controversial, with evidence for both presynaptic and postsynaptic involvement. We have used confocal microscopy and Ca(2+)-sensitive dyes to study LTP at individual visualized synapses. Synaptically evoked Ca(2+) transients were imaged in distal dendritic spines of pyramidal cells in cultured hippocampal slices, before and after the induction of LTP. At most synapses, from as early as 10 min to at least 60 min after induction, LTP was associated with an increase in the probability of a single stimulus evoking a postsynaptic Ca(2+) response. These observations provide compelling evidence of a presynaptic component to the expression of early LTP at Schaffer-associational synapses. In most cases, the store-dependent evoked Ca(2+) transient in the spine was also increased after induction, a novel postsynaptic aspect of LTP.     

Can biodiversity hotspots protect more than tropical forest plants and vertebrates?

Conservation International's biodiversity hotspots are areas of high vascular plant endemism combined with high levels of habitat destruction and land use change. Although such hotspots have also been shown to be centres for terrestrial vertebrate endemism, much less is known about how well these areas function as hotspots for other less well‐studied groups, including the hyperdiverse arthropods, other invertebrates and fungi. Because there is a close evolutionary and ecological relationship between insects and plants, we suggest that the potential role of plants as umbrella species for herbivorous insects, potentially herbivorous fungi and nematodes, and parasitic insects should be explored. Finally, we reflect on the increasing social, economic, human conflict and governance issues and the impacts of increasing land use change and global climate change that threaten the biodiversity hotspot system.     

Internal virus polarization model for virus retention by the Ultipor® VF Grade DV20 membrane

Several recent studies have reported a decline in virus retention during virus challenge filtration experiments, although the mechanism(s) governing this phenomenon for different filters remains uncertain. Experiments were performed to evaluate the retention of PP7 and PR772 bacteriophage through Ultipor VF Grade DV20 virus filters during constant pressure filtration. While the larger PR772 phage was fully retained under all conditions, a 2‐log decline in retention of the small PP7 phage was observed at high throughputs, even under conditions where there was no decline in filtrate flux. In addition, prefouling the membrane with an immunoglobulin G solution had no effect on phage retention. An internal polarization model was developed to describe the decline in phage retention arising from the accumulation of phage in the upper (reservoir) layer within the filter which increases the challenge to the lower (rejection) layer. Independent support for this internal polarization phenomenon was provided by confocal microscopy of fluorescently labeled phage within the membrane. The model was in good agreement with phage retention data over a wide range of phage titers, confirming that virus retention is throughput dependent and supporting current recommendations for virus retention validation studies. These results provide important insights into the factors governing virus retention by membrane filters and their dependence on the underlying structure of the virus filter membrane. © 2014 American Institute of Chemical Engineers Biotechnol. Prog., 30:856–863, 2014     

Faunal response to benthic and hyporheic sedimentation varies with direction of vertical hydrological exchange

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Protein Kinase C and Extracellular Signal-Regulated Kinase Regulate Movement,Attachment, Pairing and Egg Release in Schistosoma mansoni

Protein kinases C (PKCs) and extracellular signal-regulated kinases (ERKs) are evolutionary conserved cell signalling enzymes that coordinate cell function. Here we have employed biochemical approaches using ‘smart’ antibodies and functional screening to unravel the importance of these enzymes to Schistosoma mansoni physiology. Various PKC and ERK isotypes were detected, and were differentially phosphorylated (activated) throughout the various S. mansoni life stages, suggesting isotype-specific roles and differences in signalling complexity during parasite development. Functional kinase mapping in adult worms revealed that activated PKC and ERK were particularly associated with the adult male tegument, musculature and oesophagus and occasionally with the oesophageal gland; other structures possessing detectable activated PKC and/or ERK included the Mehlis'' gland, ootype, lumen of the vitellaria, seminal receptacle and excretory ducts. Pharmacological modulation of PKC and ERK activity in adult worms using GF109203X, U0126, or PMA, resulted in significant physiological disturbance commensurate with these proteins occupying a central position in signalling pathways associated with schistosome muscular activity, neuromuscular coordination, reproductive function, attachment and pairing. Increased activation of ERK and PKC was also detected in worms following praziquantel treatment, with increased signalling associated with the tegument and excretory system and activated ERK localizing to previously unseen structures, including the cephalic ganglia. These findings support roles for PKC and ERK in S. mansoni homeostasis, and identify these kinase groups as potential targets for chemotherapeutic treatments against human schistosomiasis, a neglected tropical disease of enormous public health significance.     

Membrane raft actin deficiency and altered Ca2+-induced vesiculation in stomatin-deficient overhydrated hereditary stomatocytosis

In overhydrated hereditary stomatocytosis (OHSt), the membrane raft-associated stomatin is deficient from the erythrocyte membrane. We have investigated two aspects of raft structure and function in OHSt erythrocytes. First, we have studied the distribution of other membrane and cytoskeletal proteins in rafts by analysis of detergent-resistant membranes (DRMs). In normal erythrocytes, 29% of the actin was DRM-associated, whereas in two unrelated OHSt patients the DRM-associated actin was reduced to <10%. In addition, there was a reduction in the amount of the actin-associated protein tropomodulin in DRMs from these OHSt cells. When stomatin was expressed in Madin-Darby canine kidney cells, actin association with the membrane was increased. Second, we have studied Ca2+-dependent exovesiculation from the erythrocyte membrane. Using atomic force microscopy and proteomics analysis, exovesicles derived from OHSt cells were found to be increased in number and abnormal in size, and contained greatly increased amounts of the raft proteins flotillin-1 and -2 and the calcium binding proteins annexin VII, sorcin and copine 1, while the concentrations of stomatin and annexin V were diminished. Together these observations imply that the stomatin-actin association is important in maintaining the structure and in modulating the function of stomatin-containing membrane rafts in red cells.