986 research outputs found
Descriptions of four Nearctic Procladius Skuse pupal exuviae
Associated Procladius Skuse (Holotanypus Roback) material from the Sublette collection was found to have specimens with undescribed immature stages. Pupal exuviae of two species are described for the first time: P. barbatulus Sublette and P. clavus Roback. Adult and larval features are included for P. barbatulus. In addition, specimens of Nearctic P. denticulatus Sublette are compared to Palearctic P. signatus (Zetterstedt) to determine if exuviae can separate these species or suggest that P. signatus is a senior synonym. Finally, associated pupal and larval traits of P. prolongatus Roback are compared to the original description, corroborating the theory that features are unique enough to warrant subgeneric status
Regulation of peptidoglycan synthesis during cell division in Escherichia coli
PhD ThesisBacteria surround their cytoplasmic membrane with an essential, stress-bearing macromolecule, the peptidoglycan (PG) layer. During growth and division cells extend this layer through the action of membrane-anchored peptidoglycan synthases. Presumably, sacculus growth is facilitated by dynamic multiprotein complexes which are guided by cytoskeletal elements. These complexes contain all the necessary peptidoglycan synthases and hydrolases for the enlargement of the sacculus, along with their regulators. Biochemical and genetic data gathered in recent years provides evidence for the existence of these complexes, but the molecular mechanisms they employ, and how cell wall synthesis is coordinated with the synthesis of other cell envelope layers, remain largely unknown.
In this work we have elucidated key biochemical features of a regulator of PG synthesis, LpoB. Its high resolution structure was solved by NMR spectroscopy and the interaction interface of LpoB with the major peptidoglycan synthase active during cell division in Escherichia coli, PBP1B, was determined. We show that LpoB interacts with the non-catalytic UB2H domain of PBP1B, situated between the glycosyltransferase and transpeptidase domains.
Several other proteins have previously been implicated in the regulation of PBP1B. Here we optimised an in vitro glycosyltransferase assay and investigated the effect of interacting proteins on peptidoglycan synthesis. We have shown the first evidence that multiple interaction partners, LpoB and FtsN, exert a simultaneous synergistic regulatory effect on PBP1B GTase. We also identified novel, functional interactions of PBP1B. YbgF and TolA are both members of the Tol-Pal complex which is required for outer membrane stability and its proper invagination during cell division. TolA was shown to interact with PBP1B via its transmembrane region (domain I) and moderately stimulates the GTase activity of the synthase. YbgF also interacts with PBP1B and is the first example of a negative modulator of PG synthetic activity, inhibiting the regulation of PBP1B TPase by Lpo, which is relieved by TolA. We propose that YbgF and TolA function to fine tune the regulation of PBP1B during division which allows for a proper coordination between cell wall synthesis and constriction of the OM during division in E. coli.
In summary, this work significantly enhances our understanding of the regulation of the bi-functional PG synthase active during cell division, PBP1B.The Centre for Bacterial Cell Biology, The Institute for Cell and Molecular Biosciences, Newcastle University:
The BBSRC
Paranoid thinking, cognitive bias and dangerous neighbourhoods: implications for perception of threat and expectation of victimisation
Background: Paranoid thinking is prevalent in the non-clinical population and cognitive mechanisms of heuristic reasoning and jumping to conclusions bias contributes to its formation and maintenance.
Aims: This study investigated the degree to which paranoia, perceived environmental risk, heuristic reasoning and jumping to conclusions bias (measured with the beads task) contribute to misinterpretation of neutral stimuli, and whether this informed judgements regarding vulnerability to threat and crime. It is also investigated whether impulsiveness is a confounding factor on the beads task.
Methods: Two hundred participants were recruited using a snowball-sampling method for a quantitative cross-sectional study. Participants reported demographic information, three psychometric questionnaires and two experimental tasks via an online paradigm hosted by the Bristol Online Survey tool.
Results: Participants with high paranoia scores perceived their environment to be more dangerous than those with low scores. Participants with high paranoia scores also overestimated threat in neutral stimuli and had high expectations of future victimisation. Jumping to conclusions on the beads task did not predict fear of crime outcomes, but was predicted by impulsivity.
Conclusion: Participants who demonstrated paranoid thinking were more likely to reside in perceived dangerous neighbourhoods and overestimate threat. While this could indicate a paranoid heuristic, it is a potentially rational response to prior experiences of crime and victimisation. Implications and suggestions for future research are discussed
Towards Stratified Medicine in Plasma Cell Myeloma
Plasma cell myeloma is a clinically heterogeneous malignancy accounting for approximately one to 2% of newly diagnosed cases of cancer worldwide. Treatment options, in addition to long-established cytotoxic drugs, include autologous stem cell transplant, immune modulators, proteasome inhibitors and monoclonal antibodies, plus further targeted therapies currently in clinical trials. Whilst treatment decisions are mostly based on a patientās age, fitness, including the presence of co-morbidities, and tumour burden, significant scope exists for better risk stratification, sub-classification of disease, and predictors of response to specific therapies. Clinical staging, recurring acquired cytogenetic aberrations, and serum biomarkers such as Ī²-2 microglobulin, and free light chains are in widespread use but often fail to predict the disease progression or inform treatment decision making. Recent scientific advances have provided considerable insight into the biology of myeloma. For example, gene expression profiling is already making a contribution to enhanced understanding of the biology of the disease whilst Next Generation Sequencing has revealed great genomic complexity and heterogeneity. Pathways involved in the oncogenesis, proliferation of the tumour and its resistance to apoptosis are being unravelled. Furthermore, knowledge of the tumour cell surface and its interactions with bystander cells and the bone marrow stroma enhance this understanding and provide novel targets for cell and antibody-based therapies. This review will discuss the development in understanding of the biology of the tumour cell and its environment in the bone marrow, the implementation of new therapeutic options contributing to significantly improved outcomes, and the progression towards more personalised medicine in this disorder
The fourth flight of CHESS: spectral resolution enhancements for high-resolution FUV spectroscopy
In this proceeding, we describe the scientific motivation and technical development of the Colorado Highresolution Echelle Stellar Spectrograph (CHESS), focusing on the hardware advancements and testing of components for the fourth and final launch of the payload (CHESS-4). CHESS is a far ultraviolet rocket-borne instrument designed to study the atomic-to-molecular transitions within translucent cloud regions in the interstellar medium. CHESS is an objective echelle spectrograph, which uses a mechanically-ruled echelle and a powered (f/12.4) cross-dispersing grating; it is designed to achieve a resolving power R > 100,000 over the band pass Ī»Ī» 1000ā1600 Ć
. CHESS-4 utilizes a 40 mm-diameter cross-strip anode readout microchannel plate detector, fabricated by Sensor Sciences LLC, to achieve high spatial resolution with high global count rate capabilities (ā¼ MHz). An error in the fabrication of the cross disperser limited the achievable resolution on previous launches of the payload to R ā¼ 4000. To remedy this for CHESS-4, we physically stress the echelle grating, introducing a shallow toroidal curvature to the surface of the optic. Preliminary laboratory measurements of the resulting spectrum show a factor of 4ā5 improvement to the resolving power. Results from final efficiency and reflectivity measurements for the optical components of CHESS-4 are presented, along with the pre-flight laboratory spectra and calibration results. CHESS-4 launched on 17 April 2018 aboard NASA/University of Colorado Boulder sounding rocket mission 36.333 UG. We present flight results for the observation of the Ī³ Ara sightline
Defining Meyer's loop-temporal lobe resections, visual field deficits and diffusion tensor tractography
Anterior temporal lobe resection is often complicated by superior quadrantic visual field deficits (VFDs). In some cases this can be severe enough to prohibit driving, even if a patient is free of seizures. These deficits are caused by damage to Meyer's loop of the optic radiation, which shows considerable heterogeneity in its anterior extent. This structure cannot be distinguished using clinical magnetic resonance imaging sequences. Diffusion tensor tractography is an advanced magnetic resonance imaging technique that enables the parcellation of white matter. Using seed voxels antero-lateral to the lateral geniculate nucleus, we applied this technique to 20 control subjects, and 21 postoperative patients. All patients had visual fields assessed with Goldmann perimetry at least three months after surgery. We measured the distance from the tip of Meyer's loop to the temporal pole and horn in all subjects. In addition, we measured the size of temporal lobe resection using postoperative T1-weighted images, and quantified VFDs. Nine patients suffered VFDs ranging from 22% to 87% of the contralateral superior quadrant. In patients, the range of distance from the tip of Meyer's loop to the temporal pole was 24ā43 mm (mean 34 mm), and the range of distance from the tip of Meyer's loop to the temporal horn was ā15 to +9 mm (mean 0 mm). In controls the range of distance from the tip of Meyer's loop to the temporal pole was 24ā47 mm (mean 35 mm), and the range of distance from the tip of Meyer's loop to the temporal horn was ā11 to +9 mm (mean 0 mm). Both quantitative and qualitative results were in accord with recent dissections of cadaveric brains, and analysis of postoperative VFDs and resection volumes. By applying a linear regression analysis we showed that both distance from the tip of Meyer's loop to the temporal pole and the size of resection were significant predictors of the postoperative VFDs. We conclude that there is considerable variation in the anterior extent of Meyer's loop. In view of this, diffusion tensor tractography of the optic radiation is a potentially useful method to assess an individual patient's risk of postoperative VFDs following anterior temporal lobe resection
Nonlinear surface waves in left-handed materials
We study both linear and nonlinear surface waves localized at the interface
separating a left-handed medium (i.e. the medium with both negative dielectric
permittivity and negative magnetic permeability) and a conventional (or
right-handed) dielectric medium. We demonstrate that the interface can support
both TE- and TM-polarized surface waves - surface polaritons, and we study
their properties. We describe the intensity-dependent properties of nonlinear
surface waves in three different cases, i.e. when both the LH and RH media are
nonlinear and when either of the media is nonlinear. In the case when both
media are nonlinear, we find two types of nonlinear surface waves, one with the
maximum amplitude at the interface, and the other one with two humps. In the
case when one medium is nonlinear, only one type of surface wave exists, which
has the maximum electric field at the interface, unlike waves in right-handed
materials where the surface-wave maximum is usually shifted into a
self-focussing nonlinear medium. We discus the possibility of tuning the wave
group velocity in both the linear and nonlinear cases, and show that
group-velocity dispersion, which leads to pulse broadening, can be balanced by
the nonlinearity of the media, so resulting in soliton propagation.Comment: 9 pages, 10 figure
Recommended from our members
Empathy at the heart of darkness: empathy deficits that bind the dark triad and those that mediate indirect relational aggression
The dark triad (DT) traitsāpsychopathy, narcissism and Machiavellianismāhave collectively been linked to reduced empathy and increased aggression; however, their association with distinct empathic subtypes remains unclear; and unique links to indirect relational aggression (IRA) have not been delineated. Moreover, whether dark traits should be conceptualized individually, as a dyad or as a triad with a dark core centered around the absence of empathy is debated. The current study examines (i) whether impaired empathy indeed represents a common ādark coreā binding Machiavellianism, narcissism, and psychopathy, and (ii) this core explains associations between the dark traits and IRA. Participants (N = 301, 262 F/39 M) completed measures of the DT traits, cognitive and affective empathy components and IRA (Social Exclusion, Malicious Humor and Guilt Induction). The individual traits model without links between narcissism and IRA showed the best fit, suggesting that, at least in the context of IRA, the DT traits are best viewed as three independent personality traits. Distinct cognitive and affective empathy deficits and capacities are seen in the DT. Peripheral responsivity was the only type of empathy deficit associated with all dark traits, but unrelated to IRA. Psychopathy was the strongest indicator of impaired empathy and all IRAs; however, only online simulation, an affect-related cognitive empathy facet, partially mediated the relationships of psychopathy and Machiavellianism with IRA. Whilst the unique pathways for the dark triad traits suggest stronger alignment of psychopathy and Machiavellianism in their empathic deficits and indirect aggression; the data do not support the notion that an unempathic dark core underpinning all three traits drives indirect aggression. This is the first paper delineating the specific empathic deficits involved using a facet approach and their link to indirect forms of aggression. Results therefore inform theoretical models of aggression in the DT and offer some clarity on the debates surrounding the unempathic dark core in the DT
- ā¦