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"Thompson, Rebecca"
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Human identity and identification
\"Few things are as interesting to us as our own bodies and, by extension, our own identities. In recent years, there has been a growing interest in the relationship between the body, environment and society. Reflecting upon these developments, this book examines the role of the body in human identification, in the forging of identities, and the ways in which it embodies our social worlds. The approach is integrative, taking a uniquely biological perspective and reflecting on current discourse in the social sciences. With particular reference to bioarchaeology and forensic science, the authors focus on the construction and categorisation of the body within scientific and popular discourse, examining its many tissues, from the outermost to the innermost, from the skin to DNA. Synthesising two, traditionally disparate, strands of research, this is a valuable contribution to research on human identification and the embodiment of identity.\"-- Provided by publisher.
Book
Distress and rumor exposure on social media during a campus lockdown
During crisis events, people often seek out event-related information to stay informed of what is happening. However, when information from official channels is lacking or disseminated irregularly, people may be at risk for exposure to rumors that fill the information void. We studied information-seeking during a university lockdown following an active-shooter event. In study 1, students in the lockdown (n = 3,890) completed anonymous surveys 1 week later. Those who indicated receiving conflicting information about the lockdown reported greater acute stress [standardized regression coefficient (b) = 0.07; SE = 0.01; 95% confidence interval (CI), 0.04, 0.10]. Additionally, those who reported direct contact with close others via text message (or phone) and used Twitter for critical updates during the lockdown were exposed to more conflicting information. Higher acute stress was reported by heavy social media users who trusted social media for critical updates (b = 0.06, SE = 0.01; 95% CI, 0.03, 0.10). In study 2, we employed a big data approach to explore the time course of rumor transmission across 5 hours surrounding the lockdown within a subset of the university’s Twitter followers. We also examined the patterning of distress in the hours during the lockdown as rumors about what was happening (e.g., presence of multiple shooters) spread among Twitter users. During periods without updates from official channels, rumors and distress increased. Results highlight the importance of releasing substantive updates at regular intervals during a crisis event and monitoring social media for rumors to mitigate rumor exposure and distress.
Journal Article
Collection, pre-processing and on-the-fly analysis of data for high-resolution, single-particle cryo-electron microscopy
The dramatic growth in the use of cryo-electron microscopy (cryo-EM) to generate high-resolution structures of macromolecular complexes has changed the landscape of structural biology. The majority of structures deposited in the Electron Microscopy Data Bank (EMDB) at higher than 4-Å resolution were collected on Titan Krios microscopes. Although the pipeline for single-particle data collection is becoming routine, there is much variation in how sessions are set up. Furthermore, when collection is under way, there are a range of approaches for efficiently moving and pre-processing these data. Here, we present a standard operating procedure for single-particle data collection with Thermo Fisher Scientific EPU software, using the two most common direct electron detectors (the Thermo Fisher Scientific Falcon 3 (F3EC) and the Gatan K2), as well as a strategy for structuring these data to enable efficient pre-processing and on-the-fly monitoring of data collection. This protocol takes 3–6 h to set up a typical automated data collection session.
Journal Article
Cryo-EM structure of the spinach cytochrome b6 f complex at 3.6 Å resolution
The cytochrome
b
6
f
(cyt
b
6
f
) complex has a central role in oxygenic photosynthesis, linking electron transfer between photosystems I and II and converting solar energy into a transmembrane proton gradient for ATP synthesis
1
–
3
. Electron transfer within cyt
b
6
f
occurs via the quinol (Q) cycle, which catalyses the oxidation of plastoquinol (PQH
2
) and the reduction of both plastocyanin (PC) and plastoquinone (PQ) at two separate sites via electron bifurcation
2
. In higher plants, cyt
b
6
f
also acts as a redox-sensing hub, pivotal to the regulation of light harvesting and cyclic electron transfer that protect against metabolic and environmental stresses
3
. Here we present a 3.6 Å resolution cryo-electron microscopy (cryo-EM) structure of the dimeric cyt
b
6
f
complex from spinach, which reveals the structural basis for operation of the Q cycle and its redox-sensing function. The complex contains up to three natively bound PQ molecules. The first, PQ1, is located in one cyt
b
6
f
monomer near the PQ oxidation site (Q
p
) adjacent to haem
b
p
and chlorophyll
a
. Two conformations of the chlorophyll
a
phytyl tail were resolved, one that prevents access to the Q
p
site and another that permits it, supporting a gating function for the chlorophyll
a
involved in redox sensing. PQ2 straddles the intermonomer cavity, partially obstructing the PQ reduction site (Q
n
) on the PQ1 side and committing the electron transfer network to turnover at the occupied Q
n
site in the neighbouring monomer. A conformational switch involving the haem
c
n
propionate promotes two-electron, two-proton reduction at the Q
n
site and avoids formation of the reactive intermediate semiquinone. The location of a tentatively assigned third PQ molecule is consistent with a transition between the Q
p
and Q
n
sites in opposite monomers during the Q cycle. The spinach cyt
b
6
f
structure therefore provides new insights into how the complex fulfils its catalytic and regulatory roles in photosynthesis.
A 3.6 Å resolution cryo-electron microscopy structure of the dimeric cytochrome
b
6
f
complex from spinach reveals the structural basis for operation of the quinol cycle and its redox-sensing function.
Journal Article
Cryo-EM structure of the spinach cytochrome b 6 f complex at 3.6 Å resolution
The cytochrome b
f (cytb
f ) complex has a central role in oxygenic photosynthesis, linking electron transfer between photosystems I and II and converting solar energy into a transmembrane proton gradient for ATP synthesis
. Electron transfer within cytb
f occurs via the quinol (Q) cycle, which catalyses the oxidation of plastoquinol (PQH
) and the reduction of both plastocyanin (PC) and plastoquinone (PQ) at two separate sites via electron bifurcation
. In higher plants, cytb
f also acts as a redox-sensing hub, pivotal to the regulation of light harvesting and cyclic electron transfer that protect against metabolic and environmental stresses
. Here we present a 3.6 Å resolution cryo-electron microscopy (cryo-EM) structure of the dimeric cytb
f complex from spinach, which reveals the structural basis for operation of the Q cycle and its redox-sensing function. The complex contains up to three natively bound PQ molecules. The first, PQ1, is located in one cytb
f monomer near the PQ oxidation site (Q
) adjacent to haem b
and chlorophyll a. Two conformations of the chlorophyll a phytyl tail were resolved, one that prevents access to the Q
site and another that permits it, supporting a gating function for the chlorophyll a involved in redox sensing. PQ2 straddles the intermonomer cavity, partially obstructing the PQ reduction site (Q
) on the PQ1 side and committing the electron transfer network to turnover at the occupied Q
site in the neighbouring monomer. A conformational switch involving the haem c
propionate promotes two-electron, two-proton reduction at the Q
site and avoids formation of the reactive intermediate semiquinone. The location of a tentatively assigned third PQ molecule is consistent with a transition between the Q
and Q
sites in opposite monomers during the Q cycle. The spinach cytb
f structure therefore provides new insights into how the complex fulfils its catalytic and regulatory roles in photosynthesis.
Journal Article
Cryo-EM structures of an insecticidal Bt toxin reveal its mechanism of action on the membrane
Insect pests are a major cause of crop losses worldwide, with an estimated economic cost of $470 billion annually. Biotechnological tools have been introduced to control such insects without the need for chemical pesticides; for instance, the development of transgenic plants harbouring genes encoding insecticidal proteins. The Vip3 (vegetative insecticidal protein 3) family proteins from
Bacillus thuringiensis
convey toxicity to species within the Lepidoptera, and have wide potential applications in commercial agriculture. Vip3 proteins are proposed to exert their insecticidal activity through pore formation, though to date there is no mechanistic description of how this occurs on the membrane. Here we present cryo-EM structures of a Vip3 family toxin in both inactive and activated forms in conjunction with structural and functional data on toxin–membrane interactions. Together these data demonstrate that activated Vip3Bc1 complex is able to insert into membranes in a highly efficient manner, indicating that receptor binding is the likely driver of Vip3 specificity.
The Vip3 family proteins from
Bacillus thuringiensis
are thought to exert their insecticidal activity through pore formation. Here authors present cryo-EM structures of a Vip3 family toxin in both inactive and activated forms and show the activated Vip3Bc1 in its pore forming conformation on the membrane.
Journal Article
Hydroxyl-rich macromolecules enable the bio-inspired synthesis of single crystal nanocomposites
Acidic macromolecules are traditionally considered key to calcium carbonate biomineralisation and have long been first choice in the bio-inspired synthesis of crystalline materials. Here, we challenge this view and demonstrate that low-charge macromolecules can vastly outperform their acidic counterparts in the synthesis of nanocomposites. Using gold nanoparticles functionalised with low charge, hydroxyl-rich proteins and homopolymers as growth additives, we show that extremely high concentrations of nanoparticles can be incorporated within calcite single crystals, while maintaining the continuity of the lattice and the original rhombohedral morphologies of the crystals. The nanoparticles are perfectly dispersed within the host crystal and at high concentrations are so closely apposed that they exhibit plasmon coupling and induce an unexpected contraction of the crystal lattice. The versatility of this strategy is then demonstrated by extension to alternative host crystals. This simple and scalable occlusion approach opens the door to a novel class of single crystal nanocomposites.
Calcium carbonate biomineralisation has long been linked to acidic macromolecules. Here, the authors challenge this view and show that a huge number of gold nanoparticles coated with hydroxyl-rich proteins can be incorporated into a calcium carbonate crystal while maintaining single crystal character.
Journal Article
Structure of the protective nematode protease complex H-gal-GP and its conservation across roundworm parasites
Roundworm parasite infections are a major cause of human and livestock disease worldwide and a threat to global food security. Disease control currently relies on anthelmintic drugs to which roundworms are becoming increasingly resistant. An alternative approach is control by vaccination and 'hidden antigens', components of the worm gut not encountered by the infected host, have been exploited to produce Barbervax, the first commercial vaccine for a gut dwelling nematode of any host. Here we present the structure of H-gal-GP, a hidden antigen from Haemonchus contortus, the Barber's Pole worm, and a major component of Barbervax. We demonstrate its novel architecture, subunit composition and topology, flexibility and heterogeneity using cryo-electron microscopy, mass spectrometry, and modelling. Importantly, we demonstrate that complexes with the same architecture are present in other Strongylid roundworm parasites including human hookworm. This suggests a common ancestry and the potential for development of a unified hidden antigen vaccine.
Journal Article
Cryo-EM structure of SKP1-SKP2-CKS1 in complex with CDK2-cyclin A-p27KIP1
p27KIP1 (cyclin-dependent kinase inhibitor 1B, p27) is a member of the CIP/KIP family of CDK (cyclin dependent kinase) regulators that inhibit cell cycle CDKs. p27 phosphorylation by CDK1/2, signals its recruitment to the SCF
SKP2
(S-phase kinase associated protein 1 (SKP1)-cullin-SKP2) E3 ubiquitin ligase complex for proteasomal degradation. The nature of p27 binding to SKP2 and CKS1 was revealed by the SKP1-SKP2-CKS1-p27 phosphopeptide crystal structure. Subsequently, a model for the hexameric CDK2-cyclin A-CKS1-p27-SKP1-SKP2 complex was proposed by overlaying an independently determined CDK2-cyclin A-p27 structure. Here we describe the experimentally determined structure of the isolated CDK2-cyclin A-CKS1-p27-SKP1-SKP2 complex at 3.4 Å global resolution using cryogenic electron microscopy. This structure supports previous analysis in which p27 was found to be structurally dynamic, transitioning from disordered to nascent secondary structure on target binding. We employed 3D variability analysis to further explore the conformational space of the hexameric complex and uncovered a previously unidentified hinge motion centred on CKS1. This flexibility gives rise to open and closed conformations of the hexameric complex that we propose may contribute to p27 regulation by facilitating recognition with SCF
SKP2
. This 3D variability analysis further informed particle subtraction and local refinement approaches to enhance the local resolution of the complex.
Journal Article