Pyrethroid resistance/susceptibility and differential urban/rural distribution of Anopheles arabiensis and An. gambiae s.s. malaria vectors in Nigeria and Ghana

Resistance to pyrethroid insecticides and DDT caused by the kdr gene in the malaria vector Anopheles gambiae Giles s.s. (Diptera: Culicidae) has been reported in several West African countries. To test for pyrethroid resistance in two more countries, we sampled populations of the An. gambiae complex from south-western Ghana and from urban and rural localities in Ogun State, south-west Nigeria. Adult mosquitoes, reared from field-collected larvae, were exposed to the WHO-recommended discriminating dosage of exposure for 1 h to DDT 4%, deltamethrin 0.05% or permethrin 0.75% and mortality was recorded 24 h post-exposure. Susceptibility of An. gambiae s.l. to DDT was 94-100% in Ghana and 72-100% in Nigeria, indicating low levels of DDT resistance. Deltamethrin gave the highest mortality rates: 97-100% in Ghana, 95-100% in Nigeria. Ghanaian samples of An. gambiae s.l. were fully susceptible to permethrin, whereas some resistance to permethrin was detected at 4/5 Nigerian localities (percentage mortalities 75, 82, 88, 90 and 100%), with survivors including both An. arabiensis Patton and An. gambiae s.s. identified by PCR assay. Even so, the mean knockdown time was not significantly different from a susceptible reference strain, indicating absence or low frequency of kdr-type resistance. Such low levels of pyrethroid resistance are unlikely to impair the effectiveness of pyrethroid-impregnated bednets against malaria transmission. Among Nigerian samples of An. gambiae s.l., the majority from two urban localities were identified as An. arabiensis, whereas the majority from rural localities were An. gambiae s.s. These findings are consistent with those of M. Coluzzi et al. (1979). Differences of ecological distribution between molecular forms of An. gambiae s.s. were also found, with rural samples almost exclusively of the S-form, whereas the M-form predominated in urban samples. It is suggested that 'urban island' populations of An. arabiensis and of An. gambiae s.s. M-form in the rainforest belt of West Africa might be appropriate targets for elimination of these malaria vectors by the sterile insect technique

Gambling harm: a global problem requiring global solutions

No abstract available

Quantitative proteomic analysis of the effect of 24(S),25-epoxycholesterol on SN4741 neuron cells.

Oxysterols are oxygenated derivatives of cholesterol or its precursors. One oxysterol, 24(S),25-epoxycholesterol (24(S),25-EC), which results from a shunt in the cholesterol synthesis pathway has been found at higher than expected levels in embryonic murine brain. Interestingly, the receptor that 24(5),25-EC is a ligand for, Liver X Receptor (LXR), has been implicated in neurogenesis in the ventral mid brain region of embryonic brain; an area with a high density of dopaminergic neurons. The mechanism by which LXR induces this effect is unclear. Therefore, proteomic and phosphoproteomic studies were performed using a stable isotope labelled in amino acid in cell culture (SILAC) approach in order to quantify changes in the proteome between different treatment groups in a mouse substantia nigra dopaminergic cell line (SN4741) SN4741 cells were cultured in SILAC media containing differentially isotope labelled arginine and lysine. For protein expression studies SN4741 cells were treated in serum free media with vehicle, 10muM 24(S),25-EC, or 1muM GW3965, a synthetic ligand of LXR, for 24 hours. For analysis of changes in the phosphoproteome SN4741 cells were treated in serum free media with vehicle, 10muM 24(5),25-EC, or 30muM 25- hydroxycholesterol for 6 hours. Cells were lysed and protein combined in a 1:1 ratio before trypsin digestion and peptide separation via strong cation exchange chromatography. Phosphopeptides were enriched using immobilised metal affinity chromatography (IMAC). Resulting fractions were analysed, using a data dependent LC-MS/MS method. Data was quantified using MaxQuant software in conjunction with Mascot using an IPl mouse database. In protein expression analysis known oxysterol regulated genes, via SREBP or LXR, were differentially expressed. Oxysterol treatment induced global changes in proteins involved in lipid (cholesterol, fatty acid, phospholipid, triglyceride) synthesis. LXR? protein expression increased after GW3965 and 24(5),25-EC treatment, though no change was seen on LXRp mRNA, implying that ligand binding protects LXR? from degradation. 24(S),25-EC induced changes in expression and localisation of the membrane protein caveolin-1. Also, phosphoethanolamine cytidylyltransferase and collagen type IV alpha-3-binding protein, 2 proteins involved in phospholipid synthesis, had an altered expression after 24(S),25-EC treatment suggesting a role for oxysterols in membrane homeostasis. A cytokine, macrophage colony stimulating factor, which is required for normal neuronal development and macrophage differentiation had an LXR independent increased expression after 24(S),25-EC treatment. Quantitative RT-PCR data demonstrated that proteomic changes were due to both transcriptional and post-transcriptional effects of oxysterol. In addition, studies examining changes in the mouse phosphoproteome identified a number of novel phosphorylation sites

Teaching the substitutive conception of the equals sign

A cumulative body of research has shown that children typically shift from an operational to a relational conception of the equals sign as they move through schooling. Jones (2008) argued that a truly relational conception of the equals sign comprises a substitutive component and a sameness component. Here we present two studies that build on this argument. The first investigated how the equals sign is typically presented to primary children in England, and we report that in the main an operational conception seems to be promoted. The second study measured the impact of a specially designed intervention on early secondary children's conceptions of the equals sign. Pre- and post-test data revealed that the intervention promoted substitutive and sameness components of symbolic equivalence. We consider the theoretical and pedagogical implications of the results

Measuring conceptual understanding: the case of fractions

Developing measures of the quality of understanding of a given mathematical concept has traditionally been a difficult and resource-intensive process. We tested an alternative approach, called Comparative Judgement (CJ), that is based not on psychometric instruments or clinical interviews but collective expertise. Eight mathematics education experts used CJ to assess 25 student responses to a test designed to probe conceptual understanding of fractions. Analysis revealed the CJ assessment process yielded high internal consistency, inter-rater reliability and validity. We discuss the implications of the results for using CJ to measure mathematical understanding in a variety of domains and contexts

Substitution and sameness: two components of a relational conception of the equals sign

A sophisticated and flexible understanding of the equals sign is important for arithmetic competence and for learning further mathematics, particularly algebra. Research has identified two common conceptions held by children: the equals sign as an operator, and the equals sign as signalling the same value on both sides of the equation. We argue here that as well as these two conceptions, the notion of substitution is also an important part of a sophisticated understanding of mathematical equivalence. We provide evidence from a cross-cultural study in which English and Chinese children were asked to rate the “cleverness” of operational, sameness and substitutive definitions of the equals sign. A Principle Components Analysis revealed the substitutive items were distinct from the sameness items. Furthermore, Chinese children rated the substitutive items as ‘very clever’, whereas the English children rated them as ‘not so clever’, suggesting that the notion of substitution develops differently across the two countries. Implications for developmental models of children’s understanding of equivalence are discussed

Measuring conceptual understanding using comparative judgement

The importance of improving students’ understanding of core concepts in mathematics is well established. However, assessing the impact of different teaching interventions designed to improve students’ conceptual understanding requires the validation of adequate measures. Here we propose a novel method of measuring conceptual understanding based on comparative judgement (CJ). Contrary to traditional instruments, the CJ approach allows test questions for any topic to be developed rapidly. In addition, CJ does not require a detailed rubric to represent conceptual understanding of a topic, as it is instead based on the collective knowledge of experts. In the current studies, we compared CJ to already established instruments to measure three topics in mathematics: understanding the use of p-­‐values in statistics, understanding derivatives in calculus, and understanding the use of letters in algebra. The results showed that CJ was valid as compared to established instruments, and achieved high reliability. We conclude that CJ is a quick and efficient alternative method of measuring conceptual understanding in mathematics and could therefore be particularly useful in intervention studies

Dengue Virus Hijacks a Noncanonical Oxidoreductase Function of a Cellular Oligosaccharyltransferase Complex

Dengue virus (DENV) is the most common arboviral infection globally, infecting an estimated 390 million people each year. We employed a genome-wide clustered regularly interspaced short palindromic repeat (CRISPR) screen to identify host dependency factors required for DENV propagation and identified the oligosaccharyltransferase (OST) complex as an essential host factor for DENV infection. Mammalian cells express two OSTs containing either STT3A or STT3B. We found that the canonical catalytic function of the OSTs as oligosaccharyltransferases is not necessary for DENV infection, as cells expressing catalytically inactive STT3A or STT3B are able to support DENV propagation. However, the OST subunit MAGT1, which associates with STT3B, is also required for DENV propagation. MAGT1 expression requires STT3B, and a catalytically inactive STT3B also rescues MAGT1 expression, supporting the hypothesis that STT3B serves to stabilize MAGT1 in the context of DENV infection. We found that the oxidoreductase CXXC active site motif of MAGT1 was necessary for DENV propagation, as cells expressing an AXXA MAGT1 mutant were unable to support DENV infection. Interestingly, cells expressing single-cysteine CXXA or AXXC mutants of MAGT1 were able to support DENV propagation. Utilizing the engineered peroxidase APEX2, we demonstrate the close proximity between MAGT1 and NS1 or NS4B during DENV infection. These results reveal that the oxidoreductase activity of the STT3B-containing OST is necessary for DENV infection, which may guide the development of antiviral agents targeting DENV. IMPORTANCE The host oligosaccharyltransferase (OST) complexes have been identified as essential host factors for dengue virus (DENV) replication; however, their functions during DENV infection are unclear. A previous study showed that the canonical OST activity was dispensable for DENV replication, suggesting that the OST complexes serve as scaffolds for DENV replication. However, our work demonstrates that one function of the OST complex during DENV infection is to provide oxidoreductase activity via the OST subunit MAGT1. We also show that MAGT1 associates with DENV NS1 and NS4B during viral infection, suggesting that these nonstructural proteins may be targets of MAGT1 oxidoreductase activity. These results provide insight into the cell biology of DENV infection, which may guide the development of antivirals against DENV