The antigen 43 structure reveals a molecular velcro-like mechanism of autotransporter-mediated bacterial clumping

Aggregation and biofilm formation are critical mechanisms for bacterial resistance to host immune factors and antibiotics. Autotransporter (AT) proteins, which represent the largest group of outer-membrane and secreted proteins in Gram-negative bacteria, contribute significantly to these phenotypes. Despite their abundance and role in bacterial pathogenesis, most AT proteins have not been structurally characterized, and there is a paucity of detailed information with regard to their mode of action. Here we report the structure–function relationships of Antigen 43 (Ag43a), a prototypic self-associating AT protein from uropathogenic Escherichia coli. The functional domain of Ag43a displays a twisted L-shaped β-helical structure firmly stabilized by a 3D hydrogen-bonded scaffold. Notably, the distinctive Ag43a L shape facilitates self-association and cell aggregation. Combining all our data, we define a molecular “Velcro-like” mechanism of AT-mediated bacterial clumping, which can be tailored to fit different bacterial lifestyles such as the formation of biofilms.

Structure and function of DsbA, a key bacterial oxidative folding catalyst

Since its discovery in 1991, the bacterial periplasmic oxidative folding catalyst DsbA has been the focus of intense research. Early studies addressed why it is so oxidizing and how it is maintained in its less stable oxidized state. The crystal structure of Escherichia coli DsbA (EcDsbA) revealed that the oxidizing periplasmic enzyme is a distant evolutionary cousin of the reducing cytoplasmic enzyme thioredoxin. Recent significant developments have deepened our understanding of DsbA function, mechanism, and interactions: the structure of the partner membrane protein EcDsbB, including its complex with EcDsbA, proved a landmark in the field. Studies of DsbA machineries from bacteria other than E. coli K-12 have highlighted dramatic differences from the model organism, including a striking divergence in redox parameters and surface features. Several DsbA structures have provided the first clues to its interaction with substrates, and finally, evidence for a central role of DsbA in bacterial virulence has been demonstrated in a range of organisms. Here, we review current knowledge on DsbA, a bacterial periplasmic protein that introduces disulfide bonds into diverse substrate proteins and which may one day be the target of a new class of anti-virulence drugs to treat bacterial infection. Antioxid. Redox Signal. 14, 1729–1760.

Chinese EFL students' response to an assessment policy change

In light of its documented potential for enhancing learning, formative assessment has been adopted across a range of educational contexts to improve the quality of education. The assessment innovation that the Chinese Ministry of Education (CMoE) proposed to College English in 2007 via the College English Curriculum Requirements (CECR) (CMoE, 2007), is an initiative of this kind. Considering the acknowledged influence of assessment on students’ learning, it is instructive to explore the ways in which Chinese university students respond to an assessment policy change of this magnitude, particularly as it positions them as more active learners, having the potential for increased agency and engagement in their English language learning and assessment practices. In order to explore the response of students to this assessment initiative, a case study was conducted in the context of a College English classroom. Data included an interview with a College English teacher and four students from her classes, and classroom observations and a survey of her two classes of 100 students. Analysis of the data reveals that Chinese students’ responses to the assessment policy change are influenced by a variety of sociocultural factors, including their previous English language learning and assessment experience and the extent to which they are willing to play the ‘assessment game’. These findings have implications for policy and practice.

Disturbed microtubule function and induction of micronuclei by chelate complexes of mercury(II)

Interactions of mercury(II) with the microtubule network of cells may lead to genotoxicity. Complexation of mercury(II) with EDTA is currently being discussed for its employment in detoxification processes of polluted sites. This prompted us to re-evaluate the effects of such complexing agents on certain aspects of mercury toxicity, by examining the influences of mercury(II) complexes on tubulin assembly and kinesin-driven motility of microtubules. The genotoxic effects were studied using the micronucleus assay in V79 Chinese hamster fibroblasts. Mercury(II) complexes with EDTA and related chelators interfered dose-dependently with tubulin assembly and microtubule motility in vitro. The no-effect-concentration for assembly inhibition was 1 μM of complexed Hg(II), and for inhibition of motility it was 0.05 μM, respectively. These findings are supported on the genotoxicity level by the results of the micronucleus assay, with micronuclei being induced dose-dependently starting at concentrations of about 0.05 μM of complexed Hg(II). Generally, the no-effect-concentrations for complexed mercury(II) found in the cell-free systems and in cellular assays (including the micronucleus test) were identical with or similar to results for mercury tested in the absence of chelators. This indicates that mercury(II) has a much higher affinity to sulfhydryls of cytoskeletal proteins than to this type of complexing agents. Therefore, the suitability of EDTA and related compounds for remediation of environmental mercury contamination or for other detoxification purposes involving mercury has to be questioned.

Behaviour v structure : Tribunal’s AGL Energy merger authorisation

Section 95AT of the Competition and Consumer Act 2010 (Cth) (CCA) provides that the Tribunal may grant an authorisation to acquire shares or assets that would otherwise contravene s 50. Section 95AT was inserted by the Trade Practices Legislation Amendment Act 2006 (Cth) and commenced on 1 January 2007. In Application for Authorisation of Macquarie Generation by AGL Energy Limited, (AGL Energy) the Tribunal has for the first time granted AGL Energy Limited (AGL) a conditional authorisation to acquire the assets of Macquarie Generation from the NSW Government.

Self-efficacy moderation and mediation roles on BPSD and social support influences on subjective caregiver burden in Chinese spouse caregivers of dementia patients

Background: This study aims to explore moderation and mediation roles of caregiver self-efficacy between subjective caregiver burden and (a) behavioral and psychological symptoms (BPSD) of dementia; and (b) social support. Methods: A cross-sectional study with 137 spouse caregivers of dementia patients was conducted in Shanghai. We collected demographic information for the caregiver–patient dyads, as well as information associated with dementia-related impairments, caregiver social support, caregiver self-efficacy, and SF-36. Results: Multiple regression analysis showed that caregiver self-efficacy was a moderator both between BPSD and subjective caregiver burden, and social support and subjective caregiver burden. Results also showed a partial mediation effect of caregiver self-efficacy on the impact of BPSD on subjective caregiver burden, and a mediation effect of social support on subjective caregiver burden. Caregiver self-efficacy and subjective burden significantly influenced BPSD and social support. Conclusion: Caregiver self-efficacy played an important role in the paths by which the two factors influenced subjective burden. Enhancing caregiver self-efficacy for symptom management (particularly BPSD) can be an essential strategy for determining interventions to support dementia caregivers in China, and possibly in other countries.

Vibrational spectroscopy of the borate mineral priceite : implications for the molecular structure

Priceite is a calcium borate mineral and occurs as white crystals in the monoclinic pyramidal crystal system. We have used a combination of Raman spectroscopy with complimentary infrared spectroscopy and scanning electron microscopy with Energy-dispersive X-ray Spectroscopy (EDS) to study the mineral priceite. Chemical analysis shows a pure phase consisting of B and Ca only. Raman bands at 956, 974, 991, and 1019 cm−1 are assigned to the BO stretching vibration of the B10O19 units. Raman bands at 1071, 1100, 1127, 1169, and 1211 cm−1 are attributed to the BOH in-plane bending modes. The intense infrared band at 805 cm−1 is assigned to the trigonal borate stretching modes. The Raman band at 674 cm−1 together with bands at 689, 697, 736, and 602 cm−1 are assigned to the trigonal and tetrahedral borate bending modes. Raman spectroscopy in the hydroxyl stretching region shows a series of bands with intense Raman band at 3555 cm−1 with a distinct shoulder at 3568 cm−1. Other bands in this spectral region are found at 3221, 3385, 3404, 3496, and 3510 cm−1. All of these bands are assigned to water stretching vibrations. The observation of multiple bands supports the concept of water being in different molecular environments in the structure of priceite. The molecular structure of a natural priceite has been assessed using vibrational spectroscopy.

Chinese TEFL teachers’ perceptions about research and influences on their research endeavours

English has always occupied a key position in China’s education. The quality of English education depends largely on the quality of the English teaching force. Improving the overall quality of Teaching English as a Foreign Language (TEFL) teachers entails advancing both their teaching and research competence. This study, with its focus on Chinese TEFL teachers working in a higher education institution, was set up in a context where Chinese higher education colleges are being transformed into universities and research is becoming a crucial aspect of all teachers’ work. This small-scale case study investigated a group of Chinese TEFL teachers’ perceptions about research and their individual and workplace characteristics that influenced their research endeavours. The findings revealed that Chinese TEFL teachers recognised the significance of research for teaching, professional growth and career advancement. However, lack of individual characteristics such as research and disciplinary knowledge, confidence in research and intrinsic motivation impeded their research efforts. Their institution and departments seemed to encourage research; yet, more specific financial and academic support to start and sustain their research endeavours is required. This study’s findings provide implications for both individual teachers and their institutions to engage TEFL teachers more actively in research.

Withholding and withdrawing life-sustaining treatment in a patient's best interests : Australian judicial deliberations

•Intractable disputes about withholding and withdrawing life-sustaining treatment from adults who lack capacity are rare but challenging. Judicial resolution may be needed in some of these cases. •A central concept for judicial (and clinical) decision making in this area is a patient's “best interests”. Yet what this term means is contested. •There is an emerging Supreme Court jurisprudence that sheds light on when life-sustaining treatment will, or will not, be judged to be in a patient's best interests. •Treatment that is either futile or overly burdensome is not in a patient's best interests. Although courts will consider patient and family wishes, they have generally deferred to the views of medical practitioners about treatment decisions.

Chinese resort of epic proportions

A travel article about Haikou, southern China. Publication title: "Mission Hills Resort in Hainan, China" A giant spa, 10 golf courses and amazing hazards in the swimming pool – what more do you need at a resort, asks Kari Gislason If I kept to this line, I could make it through the passage between the iceberg and the castle, however narrow...