The Anopheles gambiae glutathione transferase supergene family: annotation, phylogeny and expression profiles

BACKGROUND: Twenty-eight genes putatively encoding cytosolic glutathione transferases have been identified in the Anopheles gambiae genome. We manually annotated these genes and then confirmed the annotation by sequencing of A. gambiae cDNAs. Phylogenetic analysis with the 37 putative GST genes from Drosophila and representative GSTs from other taxa was undertaken to develop a nomenclature for insect GSTs. The epsilon class of insect GSTs has previously been implicated in conferring insecticide resistance in several insect species. We compared the expression level of all members of this GST class in two strains of A. gambiae to determine whether epsilon GST expression is correlated with insecticide resistance status. RESULTS: Two A. gambiae GSTs are alternatively spliced resulting in a maximum number of 32 transcripts encoding cytosolic GSTs. We detected cDNAs for 31 of these in adult mosquitoes. There are at least six different classes of GSTs in insects but 20 of the A. gambiae GSTs belong to the two insect specific classes, delta and epsilon. Members of these two GST classes are clustered on chromosome arms 2L and 3R respectively. Two members of the GST supergene family are intronless. Amongst the remainder, there are 13 unique introns positions but within the epsilon and delta class, there is considerable conservation of intron positions. Five of the eight epsilon GSTs are overexpressed in a DDT resistant strain of A. gambiae. CONCLUSIONS: The GST supergene family in A. gambiae is extensive and regulation of transcription of these genes is complex. Expression profiling of the epsilon class supports earlier predictions that this class is important in conferring insecticide resistance

The role of CD8+ T cell clones in immune thrombocytopenia

Immune thrombocytopenia (ITP) is traditionally considered an antibody-mediated disease. However, a number of features suggest alternative mechanisms of platelet destruction. In this study, we use a multi-dimensional approach to explore the role of cytotoxic CD8+ T cells in ITP. We characterised patients with ITP and compared them to age-matched controls using immunophenotyping, next-generation sequencing of T cell receptor (TCR) genes, single-cell RNA sequencing, and functional T cell and platelet assays. We found that adults with chronic ITP have increased polyfunctional, terminally differentiated effector memory CD8+ T cells (CD45RA+CD62L-) expressing intracellular interferon-g, tumour necrosis factor-a, and Granzyme B defining them as TEMRA cells. These TEMRA cells expand when the platelet count falls and show no evidence of physiological exhaustion. Deep sequencing of the T cell receptor showed expanded T cell clones in patients with ITP. T cell clones persisted over many years, were more prominent in patients with refractory disease, and expanded when the platelet count was low. Combined single-cell RNA and TCR sequencing of CD8+ T cells confirmed that the expanded clones are TEMRA cells. Using in vitro model systems, we show that CD8+ T cells from patients with ITP form aggregates with autologous platelets, release interferon-g and trigger platelet activation and apoptosis through TCR-mediated release of cytotoxic granules. These findings of clonally expanded CD8+ T cells causing platelet activation and apoptosis provide an antibody-independent mechanism of platelet destruction, indicating that targeting specific T-cell clones could be a novel therapeutic approach for patients with refractory ITP

Low charge overpotential of lithium-oxygen batteries with metallic Co encapsulated in single-layer graphene shell as the catalyst

Rechargeable lithium-oxygen (Li-O-2) battery has triggered tremendous attention as a promising candidate power source for portable electronics and light vehicles. Until now, a critical scientific challenge facing Li-O-2 battery is the high charge overpotential due to the sluggish oxygen evolution reaction (OER) on the oxygen electrode, which results in low energy efficiency and poor cyclability. Here, we demonstrated that nitrogen-doped single layer graphene shell encapsulating non-precious metal Co can be used as a highly efficient catalyst for Li-O-2 batteries. The catalyst showed significantly enhanced OER catalytic activity, with a charge overpotential of 0.58 V, which was remarkably lower compared with the corresponding N-free graphene encapsulating metal, metal oxide and metal-free carbon materials. DFT calculations revealed that the nitrogen dopants and enclosed metal clusters can synergistically modulate the electronic properties of the graphene surface, resulting in a dramatic reduction of the overpotentials. This study provides the possibility of the rational non-precious metal electrocatalysts designing for Li-O-2 batteries. (C) 2016 Published by Elsevier Ltd

Anion Exchange Membrane Based on Interpenetrating Polymer Network with Ultrahigh Ion Conductivity and Excellent Stability for Alkaline Fuel Cell

A high-performance anion exchange membrane (AEM) is critical for the development of alkaline fuel cell. In this work, AEMs with an interpenetrating polymer network (IPN) are synthesized. An electron microscope clearly reveals a highly efficient “ion channel” network, which is constructed with a small amount of cation exchange groups. This specially designed ion channel leads to extraordinary hydroxide conductivity (e.g., 257.8 mS cm-1 at 80 °C) of IPN AEMs at moderate ion exchange capacity (IEC=1.75 mmol g−1), as well as excellent long-term alkaline stability at harsh condition which showed that 81% of original conductivity can be retained after a long time for 1248 hours. Moreover, a remarkable peak power density of 1.20 W cm-2 (0.1 MPa backpressure) with nonprecious metal (FeNx-CNTs) as oxygen reduction reaction (ORR) catalyst in a fuel cell test was achieved. This work offers a general strategy to prepare high-performance AEMs based on IPN structure design

Characterization of the promoters of Epsilon glutathione transferases in the mosquito Anopheles gambiae and their response to oxidative stress

Epsilon class GSTs (glutathione transferases) are expressed at higher levels in Anopheles gambiae mosquitoes that are resistant to DDT [1,1,1-trichloro-2,2-bis-(p-chlorophenyl)ethane] than in insecticide-susceptible individuals. At least one of the eight Epsilon GSTs in this species, GSTe2, efficiently metabolizes DDT to DDE [1,1-dichloro-2,2-bis-(p-chlorophenyl)ethane]. In the present study, we investigated the factors regulating expression of this class of GSTs. The activity of the promoter regions of GSTe2 and GSTe3 were compared between resistant and susceptible strains by transfecting recombinant reporter constructs into an A. gambiae cell line. The GSTe2 promoter from the resistant strain exhibited 2.8-fold higher activity than that of the susceptible strain. Six polymorphic sites were identified in the 352 bp sequence immediately upstream of GSTe2. Among these, a 2 bp adenosine indel (insertion/deletion) was found to have the greatest effect on determining promoter activity. The activity of the GSTe3 promoter was elevated to a lesser degree in the DDT-resistant strain (1.3-fold). The role of putative transcription-factor-binding sites in controlling promoter activity was investigated by sequentially deleting the promoter constructs. Several putative transcription-factor-binding sites that are responsive to oxidative stress were present within the core promoters of these GSTs, hence the effect of H(2)O(2) exposure on the transcription of the Epsilon GSTs was investigated. In the DDT-resistant strain, expression of GSTe1, GSTe2 and GSTe3 was significantly increased by a 1-h exposure to H(2)O(2), whereas, in the susceptible strain, only GSTe3 expression responded to this treatment