Thermophilic vs. mesophilic bioleaching process performance

Abstract: Mesophilic and thermophilic mineral oxidising microbial cultures were compared for their capacity to leach both a complex pyritic and an arsenopyritic ore, aiming at copper and gold recovery, respectively. The mesophilic cultures are primarily based on the activity of Thiobacillus -type microorganisms, while the thermophile characteristics place them in the sulphur metabolizers branch df Archaebacteria. Study of key process variables and determination of their optimum values were carried out to provide a basis for significant physiological and technical comparison. Each microbial culture finds a preferential process application, depending on the choice of the reactor and ore.     

Chemical and microbial community analysis during aerobic biostimulation assays of non-sulfonated alkyl-benzene-contaminated groundwater

A chemical and microbial characterization of lab-scale biostimulation assays with groundwater samples taken from an industrial site in which the aquifer had been contaminated by linear non-sulfonate alkyl benzenes (LABs) was carried out for further field-scale bioremediation purposes. Two lab-scale biodegradability assays were performed, one with a previously obtained gas-oil-degrading consortium and another with the native groundwater flora. Results for the characterization of the groundwater microbial population of the site revealed the presence of an important LAB-degrading microbial population with a strong degrading capacity. Among the microorganisms identified at the site, the detection of Parvibaculum lavamentivorans, which have been described in other studies as alkyl benzene sulfonates degraders, is worth mentioning. Incubation of P. lavamentivorans DSMZ13023 with LABs as reported in this study shows for the first time the metabolic capacity of this strain to degrade such compounds. Results from the biodegradation assays in this study showed that the indigenous microbial population had a higher degrading capacity than the gas-oil-degrading consortium, indicating the strong ability of the native community to adapt to the presence of LABs. The addition of inorganic nutrients significantly improved the aerobic biodegradation rate, achieving levels of biodegradation close to 90%. The results of this study show the potential effectiveness of oxygen and nutrients as in situ biostimulation agents as well as the existence of a complex microbial community that encompasses well-known hydrocarbon- and LAS-degrading microbial populations in the aquifer studied.     

Genetic studies define MAGUK proteins as regulators of epithelial cell polarity

Polarized epithelial cells play critical roles during early embryonic development and organogenesis. Multi-domain scaffolding proteins belonging to the membrane associated guanylate kinase (MAGUK) family are commonly found at the plasma membrane of polarized epithelial cells. Genetic studies in Drosophila melanogaster and Caenorhabditis elegans have revealed that MAGUK proteins regulate various aspects of the polarized epithelial phenotype, including cell junction assembly, targeting of proteins to the plasma membrane and the organisation of polarized signalling complexes. This review will focus on the genetic studies that have contributed to our understanding of the MAGUK family members, Dlg and Lin-2/CASK, in controlling these processes. In addition, our recent genetic analysis of mouse Dlg, in combination with genetic and biochemical studies of Lin-2/CASK by others suggests a model placing Dlg and Lin-2/CASK within the same developmental pathway.     

The N-Terminal Extension of UBE2E Ubiquitin-Conjugating Enzymes Limits Chain Assembly

Protein ubiquitylation depends upon the concerted action of ubiquitin-conjugating enzymes (E2s) and ubiquitin ligases (E3s). All E2s have a conserved ubiquitin-conjugating (UBC) domain but many have variable extensions N- and C-terminal to the UBC domain. For many E2s, the function of the extension is not well understood. Here, we show that the N-terminal extension of the UBE2E proteins regulates formation of polyubiquitin chains by the processive UBC domain. Target proteins are therefore monoubiquitylated by full-length UBE2E, whereas the UBC domain alone polyubiquitylates proteins. Although the N-terminal extension of UBE2E1 is largely disordered in solution, these residues have a critical role in limiting chain building, and when fused to the highly processive E2, UBE2D2, ubiquitylation is limited. For some E2s, interaction of ubiquitin with the ‘backside’ of the UBC domain promotes polyubiquitylation. However, interaction of ubiquitin with the backside of the UBC domain of UBE2E1 does not appear to be important for processivity. This study underscores the importance of studying full-length E2 proteins and not just the highly conserved core domain.     

Nitrogen Deposition Reduces Plant Diversity and Alters Ecosystem Functioning: Field-Scale Evidence from a Nationwide Survey of UK Heathlands

Findings from nitrogen (N) manipulation studies have provided strong evidence of the detrimental impacts of elevated N deposition on the structure and functioning of heathland ecosystems. Few studies, however, have sought to establish whether experimentally observed responses are also apparent under natural, field conditions. This paper presents the findings of a nationwide field-scale evaluation of British heathlands, across broad geographical, climatic and pollution gradients. Fifty two heathlands were selected across an N deposition gradient of 5.9 to 32.4 kg ha⁻¹ yr⁻¹. The diversity and abundance of higher and lower plants and a suite of biogeochemical measures were evaluated in relation to climate and N deposition indices. Plant species richness declined with increasing temperature and N deposition, and the abundance of nitrophilous species increased with increasing N. Relationships were broadly similar between upland and lowland sites, with the biggest reductions in species number associated with increasing N inputs at the low end of the deposition range. Both oxidised and reduced forms of N were associated with species declines, although reduced N appears to be a stronger driver of species loss at the functional group level. Plant and soil biochemical indices were related to temperature, rainfall and N deposition. Litter C:N ratios and enzyme (phenol-oxidase and phosphomonoesterase) activities had the strongest relationships with site N inputs and appear to represent reliable field indicators of N deposition. This study provides strong, field-scale evidence of links between N deposition - in both oxidised and reduced forms - and widespread changes in the composition, diversity and functioning of British heathlands. The similarity of relationships between upland and lowland environments, across broad spatial and climatic gradients, highlights the ubiquity of relationships with N, and suggests that N deposition is contributing to biodiversity loss and changes in ecosystem functioning across European heathlands.     

Can the world afford to ignore biotechnology solutions that address food insecurity?

Genetically engineered (GE) crops can be used as part of a combined strategy to address food insecurity, which is defined as a lack of sustainable access to safe and nutritious food. In this article, we discuss the causes and consequences of food insecurity in the developing world, and the indirect economic impact on industrialized countries. We dissect the healthcare costs and lost productivity caused by food insecurity, and evaluate the relative merits of different intervention programs including supplementation, fortification and the deployment of GE crops with higher yields and enhanced nutritional properties. We provide clear evidence for the numerous potential benefits of GE crops, particularly for small-scale and subsistence farmers. GE crops with enhanced yields and nutritional properties constitute a vital component of any comprehensive strategy to tackle poverty, hunger and malnutrition in developing countries and thus reduce the global negative economic effects of food insecurity.     

Simultaneous occurrence of sarcomas in a husband and wife

The simultaneous occurrence of sarcomas in a husband and wife is documented. The wife first presented with an undifferentiated uterine sarcoma, and within six months of the onset of her disease her husband developed an anaplastic liposarcoma. This finding is considered in the light of recent evidence suggesting a possible viral etiology for human sarcomas.     

The TLR4 D299G and T399I SNPs Are Constitutively Active to Up-Regulate Expression of Trif-Dependent Genes

Dysregulated Toll-Like Receptor (TLR) signalling and genetic polymorphisms in these proteins are linked to many human diseases. We investigated TLR4 functional variants D299G and T399I to assess the impact on LPS-induced responsiveness in comparison to wild-type TLR4. The mechanism by which this occurs in unclear as these SNPs do not lie within the lipid A binding domain or dimerisation sites of the LPS-TLR4/MD2 receptor complexes. Transfection of TLR4D299G, TLR4T399I or TLR4D299G. T399I into HEK cells resulted in constitutive activation of an NF-κB reporter gene and a blunting of the LPS-induced reporter activation compared to WT-TLR4. Unstimulated human monocyte/macrophages, from patients with the D299G and T399I SNPs demonstrated a downregulation of many genes, particularly Tram/Trif signalling pathway constitutents compared to the TLR4 wild-type subjects supporting the concept of basal receptor activity. Monocyte/macrophages from carriers of the TLR4 D299G and T399I polymorphisms stimulated with LPS showed >6 fold lower levels of NF-κB and ∼12 fold higher IFN-β gene expression levels compared to wild-type subjects (P<0.05; MWU test) and dramatically altered resultant cytokine profiles. We conclude that these TLR4 SNPs affect constitutive receptor activity which impacts on the hosts ability to respond to LPS challenge leading to a dysregulated sub-optimal immune response to infection.     

Assessment of Cerebral Lateralization in Children using Functional Transcranial Doppler Ultrasound (fTCD)

There are many unanswered questions about cerebral lateralization. In particular, it remains unclear which aspects of language and nonverbal ability are lateralized, whether there are any disadvantages associated with atypical patterns of cerebral lateralization, and whether cerebral lateralization develops with age. In the past, researchers interested in these questions tended to use handedness as a proxy measure for cerebral lateralization, but this is unsatisfactory because handedness is only a weak and indirect indicator of laterality of cognitive functions¹. Other methods, such as fMRI, are expensive for large-scale studies, and not always feasible with children².Here we will describe the use of functional transcranial Doppler ultrasound (fTCD) as a cost-effective, non-invasive and reliable method for assessing cerebral lateralization. The procedure involves measuring blood flow in the middle cerebral artery via an ultrasound probe placed just in front of the ear. Our work builds on work by Rune Aaslid, who co-introduced TCD in 1982, and Stefan Knecht, Michael Deppe and their colleagues at the University of Münster, who pioneered the use of simultaneous measurements of left- and right middle cerebral artery blood flow, and devised a method of correcting for heart beat activity. This made it possible to see a clear increase in left-sided blood flow during language generation, with lateralization agreeing well with that obtained using other methods³.The middle cerebral artery has a very wide vascular territory (see Figure 1) and the method does not provide useful information about localization within a hemisphere. Our experience suggests it is particularly sensitive to tasks that involve explicit or implicit speech production. The ''gold standard'' task is a word generation task (e.g. think of as many words as you can that begin with the letter ''B'') ⁴, but this is not suitable for young children and others with limited literacy skills. Compared with other brain imaging methods, fTCD is relatively unaffected by movement artefacts from speaking, and so we are able to get a reliable result from tasks that involve describing pictures aloud^5,6. Accordingly, we have developed a child-friendly task that involves looking at video-clips that tell a story, and then describing what was seen.