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We present a new set of index-based measurements of [$\alpha$/Fe] for a sample of 2093 galaxies in the SAMI Galaxy Survey. Following earlier work, we fit a global relation between [$\alpha$/Fe] and the galaxy velocity dispersion $\sigma$ for red sequence galaxies, [$\alpha$/Fe]=(0.378$\pm$0.009)log($\sigma$/100)+(0.155$\pm$0.003). We observe a correlation between the residuals and the local environmental surface density, whereas no such relation exists for blue cloud galaxies. In the full sample, we find that elliptical galaxies in high-density environments are $\alpha$-enhanced by up to 0.057$\pm$0.014 dex at velocity dispersions $\sigma$, Comment: 15 pages, 9 figures. Revised after comments from referee

Musical theater (MT) performers are required to sing in several different styles, requiring different registration (quality) and different use of vibrato. Many measures of vibrato in MT performers are made in laboratory settings, studying a limited set of pitches, intensities, and vowels, using amateur and not well-defined professional singers. It is unclear if these observations are observed in well-known professional MT singers, during live instrumentally accompanied legit and belt performances.Descriptive from a convenience sample.Five well-known MT performers' recordings of one legit and one belt performance were downloaded for analysis of vocal vibrato. The vocal part was extracted from the recording and each note demarcated with and without vibrato. The pitch track of each note was analyzed for average pitch, duration, the proportion of a note sung with vibrato, if present, and written to file. The pitch track (f0 and time stamps) was written to a separate file for further analysis. This analysis consisted of vibrato rate (Hz), vibrato extent (semitones), and cycle-to-cycle perturbation (jitter-local and shimmer-local).The most consistent finding was that the belt performances of the five singers had lesser proportion of notes sung with vibrato than their legit performances. The next consistent finding was that during belt performances, when vibrato was used, it was for a shorter duration within a note. There was a trend for the average rate of vibrato to be slower in the belt performances, but not to a substantial degree. There was no clear difference between legit and belt performances for vibrato extent or cycle-to-cycle perturbation.For these five performers, the strategy for the use of vibrato most often employed for differentiating the two singing styles was using less vibrato and when used to engage it for a shorter portion of a sung note. We believe this study offers reasonable ecological validity in how professional MT performers utilize vibrato to distinguish between belt and legit styles of singing. Vibrato rate and extent are subject to a number of factors which may not be in direct control of the singer. However, learning to sing with and without vibrato and the duration to which it is produced within a note may be a useful training strategy for students of MT.

This article explores the relationship between the FARC (the Revolutionary Armed Forces of Colombia) and football in Colombia. It argues that until the presidency of Juan Manuel Santos, the FARC ha...

We explore a sample of 1492 galaxies with measurements of the mean stellar population properties and the spin parameter proxy, $\lambda_{R_{\rm{e}}}$, drawn from the SAMI Galaxy Survey. We fit a global $\left[\alpha/\rm{Fe}\right]$-$\sigma$ relation, finding that $\left[\alpha/\rm{Fe}\right]=(0.395\pm0.010)\rm{log}_{10}\left(\sigma\right)-(0.627\pm0.002)$. We observe an anti-correlation between the residuals $\Delta\left[\alpha/\rm{Fe}\right]$ and the inclination-corrected $\lambda_{\,R_{\rm{e}}}^{\rm{\,eo}}$, which can be expressed as $\Delta\left[\alpha/\rm{Fe}\right]=(-0.057\pm0.008)\lambda_{\,R_{\rm{e}}}^{\rm{\,eo}}+(0.020\pm0.003)$. The anti-correlation appears to be driven by star-forming galaxies, with a gradient of $\Delta\left[\alpha/\rm{Fe}\right]\sim(-0.121\pm0.015)\lambda_{\,R_{\rm{e}}}^{\rm{\,eo}}$, although a weak relationship persists for the subsample of galaxies for which star formation has been quenched. We take this to be confirmation that disk-dominated galaxies have an extended duration of star formation. At a reference velocity dispersion of 200 km s$^{-1}$, we estimate an increase in half-mass formation time from $\sim$0.5 Gyr to $\sim$1.2 Gyr from low- to high-$\lambda_{\,R_{\rm{e}}}^{\rm{\,eo}}$ galaxies. Slow rotators do not appear to fit these trends. Their residual $\alpha$-enhancement is indistinguishable from other galaxies with $\lambda_{\,R_{\rm{e}}}^{\rm{\,eo}}\lessapprox0.4$, despite being both larger and more massive. This result shows that galaxies with $\lambda_{\,R_{\rm{e}}}^{\rm{\,eo}}\lessapprox0.4$ experience a similar range of star formation histories, despite their different physical structure and angular momentum., Comment: 12 pages, 9 figures

Autistic people report difficulties with the demands of a neurotypical world, but little research has assessed the impact of the environment on such difficulties. We investigated the effect of ambient sounds on decision-making and heart rate variability. Adults without intellectual disability were allocated to autistic ( n = 38) or neurotypical ( n = 37) groups matched on age, intellectual functioning and self-reported gender. Participants completed a shopping decision-making task in three randomly ordered sound conditions: no sound, non-social shopping sound (e.g. fridges humming) and social shopping sound (e.g. people talking). Decision-making latency, decision-making consistency, and heart rate variability were measured. Participants also provided qualitative reports of their experiences. Qualitative analyses indicated that autistic participants experienced (1) the non-social and social sound conditions more negatively than the no sound condition and (2) the social sound condition more negatively than neurotypical participants. However, there were no statistically significant differences in decision-making latency, decision-making consistency, or heart rate variability across sound conditions and participant groups. Further research should consider alternative quantitative measures to explore subjective experience to help understand further which aspects of the environment autistic people are sensitive to, in turn, enabling more evidence-based autism-friendly changes to be made. Lay abstract Many autistic people report difficulties making decisions during everyday tasks, such as shopping. To examine the effect of sounds on decision-making, we developed a supermarket task where people watched a film shown from the shopper’s perspective and were asked to make decisions between different products. The task was divided into three sections and participants completed each section in a different auditory environment: (1) no sounds, (2) non-social sounds (e.g. fridges humming) and (3) social sounds (e.g. people talking). Thirty-eight autistic and 37 neurotypical adults took part. We measured decision-making by examining how long it took to make a decision and how consistent people were with their decisions. We also measured heart rate variability because this biological response provides a measure of anxiety. After the supermarket shopping task, participants told us in their own words about their experiences. Autistic participants said that they found the non-social and social sound conditions more difficult than the no sound condition, and autistic participants found the social sound condition more negative than neurotypical participants. However, decision-making and heart rate variability were similar for autistic and neurotypical participants across the sound conditions, suggesting that these measures may not have been sensitive enough to reflect the experiences the autistic participants reported. Further research should consider alternative measures to explore the experiences reported by autistic people to help us understand which specific aspects of the environment autistic people are sensitive to. This, in turn, may enable more specific and evidence-based autism-friendly changes to be made.

Synopsis Previous studies have focused on documenting shape variation in the caudal vertebrae in chameleons underlying prehensile tail function. The goal of this study was to test the impact of this variation on tail function using multibody dynamic analysis (MDA). First, observations from dissections and 3D reconstructions generated from contrast-enhanced µCT scans were used to document regional variation in arrangement of the caudal muscles along the antero-posterior axis. Using MDA, we then tested the effect of vertebral shape geometry on biomechanical function. To address this question, four different MDA models were built: those with a distal vertebral shape and with either a distal or proximal musculature, and reciprocally the proximal vertebral shape with either the proximal or distal musculature. For each muscle configuration, we calculated the force required in each muscle group for the muscle force to balance an arbitrary external force applied to the model. The results showed that the models with a distal-type of musculature are the most efficient, regardless of vertebral shape. Our models also showed that the m. ilio-caudalis pars dorsalis is least efficient when combining the proximal vertebral shape and distal musculature, highlighting the importance of the length of the transverse process in combination with the lever-moment arm onto which muscle force is exerted. This initial model inevitably has a number of simplifications and assumptions, however its purpose is not to predict in vivo forces, but instead reveals the importance of vertebral shape and muscular arrangement on the total force the tail can generate, thus providing a better understanding of the biomechanical significance of the regional variations on tail grasping performance in chameleons.

Although a functional relationship between bone structure and mastication has been shown in some regions of the rabbit skull, the biomechanics of the whole cranium during mastication have yet to be fully explored. In terms of cranial biomechanics, the rabbit is a particularly interesting species due to its uniquely fenestrated rostrum, the mechanical function of which is debated. In addition, the rabbit processes food through incisor and molar biting within a single bite cycle, and the potential influence of these bite modes on skull biomechanics remains unknown. This study combined the in silico methods of multi-body dynamics and finite element analysis to compute musculoskeletal forces associated with a range of incisor and molar biting, and to predict the associated strains. The results show that the majority of the cranium, including the fenestrated rostrum, transmits masticatory strains. The peak strains generated over all bites were found to be attributed to both incisor and molar biting. This could be a consequence of a skull shape adapted to promote an even strain distribution for a combination of infrequent incisor bites and cyclic molar bites. However, some regions, such as the supraorbital process, experienced low peak strain for all masticatory loads considered, suggesting such regions are not designed to resist masticatory forces.

Cranial morphology in lepidosaurs is highly disparate and characterised by the frequent loss or reduction of bony elements. In varanids and geckos, the loss of the postorbital bar is associated with changes in skull shape, but the mechanical principles underlying this variation remain poorly understood. Here, we sought to determine how the overall cranial architecture and the presence of the postorbital bar relate to the loading and deformation of the cranial bones during biting in lepidosaurs. Using computer-based simulation techniques, we compared cranial biomechanics in the varanid Varanus niloticus and the teiid Salvator merianae, two large, active foragers. The overall strain magnitude and distribution across the cranium were similar in the two species, despite lower strain gradients in V. niloticus. In S. merianae, the postorbital bar is important for resistance of the cranium to feeding loads. The postorbital ligament, which in varanids partially replaces the postorbital bar, does not affect bone strain. Our results suggest that the reduction of the postorbital bar impaired neither biting performance nor the structural resistance of the cranium to feeding loads in V. niloticus. Differences in bone strain between the two species might reflect demands imposed by feeding and non-feeding functions on cranial shape. Beyond variation in cranial bone strain related to species-specific morphological differences, our results reveal that similar mechanical behaviour is shared by lizards with distinct cranial shapes. Contrary to the situation in mammals, the morphology of the circumorbital region, calvaria and palate appears to be important for withstanding high feeding loads in these lizards., Summary: In vivo measurements and computer-based simulations of the cranial mechanics of two large lizards indicate that similar mechanical behaviour is shared by lizards with distinct cranial architecture, and show the importance of the postorbital bar in resisting the feeding loads.

Remodelling and adaptation of bone within the pelvis is believed to be influenced by the mechanical strains generated during locomotion. Variation in the cortical bone thickness observed in the prenatal ilium has been linked to the musculoskeletal loading associated with in utero movements; for example the development of a thicker gluteal cortex is a possible response to contractions of the gluteal muscles. This study examines if the strains generated in the prenatal iliac cortex due to musculoskeletal loading in utero are capable of initiating bone remodelling to either maintain homeostasis or form new bone. Computational modelling techniques were used firstly to predict the muscle forces and resultant joint reaction force acting on the pelvis during a range of in utero movements. Finite element analyses were subsequently performed to calculate the von Mises strains induced in the prenatal ilium. The results demonstrated that strains generated in the iliac cortex were above the thresholds suggested to regulate bone remodelling to either maintain homeostasis or form new bone. Further simulations are required to investigate the extent to which the heterogeneous cortex forms in response to these strains (i.e., remodelling) or if developmental bone modelling plays a more pivotal role.

Alveolar bone, together with the underlying trabecular bone, fulfils an important role in providing structural support against masticatory forces. Diseases such as osteoporosis or periodontitis cause alveolar bone resorption which weakens this structural support and is a major cause of tooth loss. However, the functional relationship between alveolar bone remodelling within the molar region and masticatory forces is not well understood. This study investigated this relationship by comparing mammalian species with different diets and functional loading (Felis catus, Cercocebus atys, Homo sapiens, Sus scrofa, Oryctolagus cuniculus, Ovis aries). We performed histomorphometric analyses of trabecular bone morphology (bone volume fraction, trabecular thickness and trabecular spacing) and quantified the variation of bone and tooth root volumes along the tooth row. A principal component analysis and non-parametric MANOVA showed statistically significant differences in trabecular bone morphology between species with contrasting functional loading, but these differences were not seen in sub-adult specimens. Our results support a strong, but complex link between masticatory function and trabecular bone morphology. Further understanding of a potential functional relationship could aid the diagnosis and treatment of mandibular diseases causing alveolar bone resorption, and guide the design and evaluation of dental implants.

Histone deacetylase (HDAC) inhibitors are proven anticancer therapeutics and have potential in the treatment of many other diseases including HIV infection, Alzheimer's disease, and Friedreich's ataxia. A problem with the currently available HDAC inhibitors is that they have limited specificity and target multiple deacetylases. Designing isoform-selective inhibitors has proven challenging due to similarities in the structure and chemistry of HDAC active sites. However, the fact that HDACs 1, 2, and 3 are recruited to several large multi-subunit complexes, each with particular biological functions, raises the possibility of specifically inhibiting individual complexes. This may be assisted by recent structural and functional information about the assembly of these complexes. Here, we review the available structural information and discuss potential targeting strategies.

Proteomic analysis of histones has shown that they are subject to a superabundance of acylations, which extend far beyond acetylation, to include: crotonylation, propionylation, butyrylation, malonylation, succinylation, β-hydroxybutyrylation and 2-hydroxyisobutyrylation. To date, much of the functional data has focussed on histone crotonylation which, similar to acetylation, has been associated with positive gene regulation and is added by the acyltransferase, p300. Although Sirtuins 1–3, along with HDAC3, have been shown to possess decrotonylase activity in vitro, there is relatively little known about the regulation of histone crotonylation in vivo. Here we show that Histone Deacetylase 1 and 2 (HDAC1/2), the catalytic core of numerous co-repressor complexes, are important histone decrotonylase enzymes. A ternary complex of HDAC1/CoREST1/LSD1 is able to hydrolyse both histone H3 Lys18-acetyl (H3K18ac) and H3 Lys18-crotonyl (H3K18cr) peptide substrates. Genetic deletion of HDAC1/2 in ES cells increases global levels of histone crotonylation and causes an 85% reduction in total decrotonylase activity. Furthermore, we mapped H3K18cr in cells using ChIP-seq, with and without HDAC1/2, and observed increased levels of crotonylation, which largely overlaps with H3K18ac in the vicinity of transcriptional start sites. Collectively, our data indicate that HDAC1/2 containing complexes are critical regulators of histone crotonylation in vivo.

Insect head shapes are remarkably variable but the influences of these changes on biomechanical performance are unclear. Among “basal” winged insects, such as dragonflies, mayflies, earwigs, and stoneflies, some of the most prominent anatomical changes are the general mouthpart orientation, eye size and the connection of the endoskeleton to the head. Here, we assess these variations for the first time using modern engineering methods including multibody dynamics modelling and finite element analysis in order to quantify and compare their influence on overall head performance. We show that a range of peculiar structures such as the genal/subgenal, epistomal, and circumoccular areas are consistently highly loaded in all species, despite drastically differing morphologies in species with forward projecting (prognathous) and downwards projecting (orthognathous) mouthparts. Sensitivity analyses show that the presence of eyes has a negligible influence on head capsule strain if a circumoccular ridge is present. In contrast, the connection of the dorsal endoskeletal arms to the head capsule especially affects overall head loading in species with downward projecting mouthparts. Analysis of the relative strains between species for each head region reveals that most head regions map onto a similar biomechanical performance space thus showing a many to one mapping of differing forms to the same functional space. Concerted changes in head substructures such as the subgenal area, the endoskeleton and the epistomal area lead to a consistent relative loading pattern in prognathous and orthognathous insects. It appears that biting-chewing loads are managed by a system of strengthening ridges on the head capsule irrespective of the general mouthpart and head orientation. Concerted changes in ridge and endoskeleton configuration allow more radical anatomical changes such as general mouthpart orientation which could be an explanation for the variability of this trait among insects. In an evolutionary context, many to one mapping of diverse forms to similar functions indeed could have fostered the dynamic diversification processes seen in insects.

Proceedings of the Royal Society of London / B 284(1848), 20162412 -(2017). doi:10.1098/rspb.2016.2412, Despite large-scale molecular attempts, the relationships of the basal winged insect lineages dragonflies, mayflies and neopterans, are still unresolved. Other data sources, such as morphology, suffer from unclear functional dependencies of the structures considered, which might mislead phylogenetic inference. Here, we assess this problem by combining for the first time biomechanics with phylogenetics using two advanced engineering techniques, multibody dynamics analysis and finite-element analysis, to objectively identify functional linkages in insect head structures which have been used traditionally to argue basal winged insect relationships. With a biomechanical model of unprecedented detail, we are able to investigate the mechanics of morphological characters under biologically realistic load, i.e. biting. We show that a range of head characters, mainly ridges, endoskeletal elements and joints, are indeed mechanically linked to each other. An analysis of character state correlation in a morphological data matrix focused on head characters shows highly significant correlation of these mechanically linked structures. Phylogenetic tree reconstruction under different data exclusion schemes based on the correlation analysis unambiguously supports a sistergroup relationship of dragonflies and mayflies. The combination of biomechanics and phylogenetics as it is proposed here could be a promising approach to assess functional dependencies in many organisms to increase our understanding of phenotypic evolution., Published by The Royal Society, London

Transient transfection of human embryonic kidney cells (HEK 293) enables the rapid and affordable labscale production of recombinant proteins. In this chapter protocols for the expression and purification of both secreted and intracellular proteins using transient expression in HEK 293 cells are described.

The NuRD complex is a multi-protein transcriptional corepressor that couples histone deacetylase and ATP-dependent chromatin remodelling activities. The complex regulates the higher-order structure of chromatin, and has important roles in the regulation of gene expression, DNA damage repair and cell differentiation. HDACs 1 and 2 are recruited by the MTA1 corepressor to form the catalytic core of the complex. The histone chaperone protein RBBP4, has previously been shown to bind to the carboxy-terminal tail of MTA1. We show that MTA1 recruits a second copy of RBBP4. The crystal structure reveals an extensive interface between MTA1 and RBBP4. An EM structure, supported by SAXS and crosslinking, reveals the architecture of the dimeric HDAC1:MTA1:RBBP4 assembly which forms the core of the NuRD complex. We find evidence that in this complex RBBP4 mediates interaction with histone H3 tails, but not histone H4, suggesting a mechanism for recruitment of the NuRD complex to chromatin. DOI: http://dx.doi.org/10.7554/eLife.13941.001, eLife digest The correct regulation of our genes is essential for life. Genes are actively switched on or off through the action of assemblies of proteins that act together as molecular machines. Some of these machines alter the way that DNA is packaged inside cells. Packaged DNA – called chromatin – consists of DNA wrapped around proteins called histones, which together form structures called nucleosomes. Changing how tightly nucleosomes are packed together can alter whether a gene is active: tighter packing makes it harder to access the genes in that stretch of DNA and therefore inactivates them. In humans, an assembly of proteins called the NuRD complex makes chromatin more compact by removing acetyl groups from nucleosomes. This complex is important for early development and for the stability and repair of our genes. Three proteins make up its core: HDAC1, which removes the acetyl group from the nucleosome; MTA1, which acts as a scaffold to hold the complex together; and RBBP4, which enables the complex to interact with nucleosomes. Understanding how protein complexes are assembled tells us a lot about how they work. Millard et al. have therefore used a number of structural techniques to investigate the three-dimensional architecture of the three core proteins in the NuRD complex. The resulting structures have revealed how the HDAC1, MTA1 and RBBP4 proteins interact to influence how the complex is recruited to nucleosomes. The next step will be to assemble all the remaining proteins of the NuRD complex to understand its architecture as a whole. DOI: http://dx.doi.org/10.7554/eLife.13941.002

Highlights ► Co-repressors SMRT/NCoR act as “hub proteins”. ► SMRT/NCoR integrate transcription factor and histone modifying enzyme signaling. ► Structures of co-repressor complexes. ► Structural studies provide mechanistic, and potentially therapeutic, insights., Co-repressor proteins, such as SMRT and NCoR, mediate the repressive activity of unliganded nuclear receptors and other transcription factors. They appear to act as intrinsically disordered “hub proteins” that integrate the activities of a range of transcription factors with a number of histone modifying enzymes. Although these co-repressor proteins are challenging targets for structural studies due to their largely unstructured character, a number of structures have recently been determined of co-repressor interaction regions in complex with their interacting partners. These have yielded considerable insight into the mechanism of assembly of these complexes, the structural basis for the specificity of the interactions and also open opportunities for targeting these interactions therapeutically.

The falx cerebri and the tentorium cerebelli are two projections of the dura mater in the cranial cavity which ossify to varying degrees in some mammalian species. The idea that the ossification of these structures may be necessary to support the loads arising during feeding has been proposed and dismissed in the past, but never tested quantitatively. To address this, a biomechanical model of a domestic cat ( Felis silvestris catus ) skull was created and the material properties of the falx and tentorium were varied for a series of loading regimes incorporating the main masticatory and neck muscles during biting. Under these loading conditions, ossification of the falx cerebri does not have a significant impact on the stress in the cranial bones. In the case of the tentorium, however, a localized increase in stress was observed in the parietal and temporal bones, including the tympanic bulla, when a non-ossified tentorium was modelled. These effects were consistent across the different analyses, irrespective of loading regime. The results suggest that ossification of the tentorium cerebelli may play a minor role during feeding activities by decreasing the stress in the back of the skull.

Histone deacetylase 3 removes acetyl groups from lysine residues, thereby modifying protein function. It is found in both the nucleus and the cytoplasm. We have discovered that it can indirectly deacetylate tubulin, a cytoplasmic protein that forms microtubules, thus modifying the microtubule., Histone deacetylase 3 (HDAC3), a member of the Class I subfamily of HDACs, is found in both the nucleus and the cytoplasm. Its roles in the nucleus have been well characterized, but its cytoplasmic roles are still not elucidated fully. We found that blocking HDAC3 activity using MI192, a compound specific for HDAC3, modulated tubulin acetylation in the human prostate cancer cell line PC3. A brief 1 h treatment of PC3 cells with MI192 significantly increased levels of tubulin acetylation and ablated the dynamic behaviour of microtubules in live cells. siRNA-mediated knockdown (KD) of HDAC3 in PC3 cells, significantly increased levels of tubulin acetylation, and overexpression reduced it. However, the active HDAC3–silencing mediator of retinoic and thyroid receptors (SMRT)–deacetylase-activating domain (DAD) complex did not directly deacetylate tubulin in vitro. These data suggest that HDAC3 indirectly modulates tubulin acetylation.

The use of finite element analysis (FEA) to investigate the biomechanics of anatomical systems critically relies on the specification of physiologically representative boundary conditions. The biomechanics of the pelvis has been the specific focus of a number of FEA studies previously, but it is also a key aspect in other investigations of, for example, the hip joint or new design of hip prostheses. In those studies, the pelvis has been modelled in a number of ways with a variety of boundary conditions, ranging from a model of the whole pelvic girdle including soft tissue attachments to a model of an isolated hemi-pelvis. The current study constructed a series of FEA models of the same human pelvis to investigate the sensitivity of the predicted stress distributions to the type of boundary conditions applied, in particular to represent the sacro-iliac joint and pubic symphysis. Varying the method of modelling the sacro-iliac joint did not produce significant variations in the stress distribution, however changes to the modelling of the pubic symphysis were observed to have a greater effect on the results. Over-constraint of the symphysis prevented the bending of the pelvis about the greater sciatic notch, and underestimated high stresses within the ilium. However, permitting medio-lateral translation to mimic widening of the pelvis addressed this problem. These findings underline the importance of applying the appropriate boundary conditions to FEA models, and provide guidance on suitable methods of constraining the pelvis when, for example, scan data has not captured the full pelvic girdle. The results also suggest a valid method for performing hemi-pelvic modelling of cadaveric or archaeological remains which are either damaged or incomplete.

COPI-coated vesicles mediate retrograde transport from the Golgi back to the ER and intra-Golgi transport. The cytosolic precursor of the COPI coat, the heptameric coatomer complex, can be thought of as composed of two subcomplexes. The first consists of the beta-, gamma-, delta- and zeta-COP subunits which are distantly homologous to AP clathrin adaptor subunits. The second consists of the alpha-, beta'- and epsilon-COP subunits. Here, we present the structure of the appendage domain of gamma-COP and show that it has a similar overall fold as the alpha-appendage of AP2. Again, like the alpha-appendage the gamma-COP appendage possesses a single protein/protein interaction site on its platform subdomain. We show that in yeast this site binds to the ARFGAP Glo3p, and in mammalian gamma-COP this site binds to a Glo3p orthologue, ARFGAP2. On the basis of mutations in the yeast homologue of gamma-COP, Sec21p, a second binding site is proposed to exist on the gamma-COP appendage that interacts with the alpha,beta',epsilon COPI subcomplex.

Alveolar bone remodelling is vital for the success of dental implants and orthodontic treatments. However, the underlying biomechanical mechanisms, in particular the function of the periodontal ligament (PDL) in bone loading and remodelling, are not well understood. The PDL is a soft fibrous connective tissue that joins the tooth root to the alveolar bone and plays a critical role in the transmission of loads from the tooth to the surrounding bone. However, due to its complex structure, small size and location within the tooth socket it is difficult to study in vivo. Finite element analysis (FEA) is an ideal tool with which to investigate the role of the PDL, however inclusion of the PDL in FE models is complex and time consuming, therefore consideration must be given to how it is included. The aim of this study was to investigate the effects of including the PDL and its fibrous structure in mandibular finite element models. A high-resolution model of a human molar region was created from micro-computed tomography scans. This is the first time that the fibrous structure of the PDL has been included in a model with realistic tooth and bone geometry. The results show that omission of the PDL creates a more rigid model, reducing the strains observed in the mandibular corpus which are of interest when considering mandibular functional morphology. How the PDL is modelled also affects the strains. The inclusion of PDL fibres alters the strains in the mandibular bone, increasing the strains in the tooth socket compared to PDL modelled without fibres. As strains in the alveolar bone are thought to play a key role in bone remodelling during orthodontic tooth movement, future FE analyses aimed at improving our understanding and management of orthodontic treatment should include the fibrous structure of the PDL.

Biomechanical analysis of juvenile pelvic growth can be used in the evaluation of medical devices and investigation of hip joint disorders. This requires access to scan data of healthy juveniles, which are not always freely available. This article analyses the application of a geometric morphometric technique, which facilitates the reconstruction of the articulated juvenile pelvis from cadaveric remains, in biomechanical modelling. The sensitivity of variation in reconstructed morphologies upon predicted stress/strain distributions is of particular interest. A series of finite element analyses of a 9-year-old hemi-pelvis were performed to examine differences in predicted strain distributions between a reconstructed model and the originally fully articulated specimen. Only minor differences in the minimum principal strain distributions were observed between two varying hemi-pelvic morphologies and that of the original articulation. A Wilcoxon rank-sum test determined there was no statistical significance between the nodal strains recorded at 60 locations throughout the hemi-pelvic structures. This example suggests that finite element models created by this geometric morphometric reconstruction technique can be used with confidence, and as observed with this hemi-pelvis model, even a visual morphological difference does not significantly affect the predicted results. The validated use of this geometric morphometric reconstruction technique in biomechanical modelling reduces the dependency on clinical scan data.

Transient transfection of human embryonic kidney cells (HEK 293) enables the rapid and affordable lab-scale production of recombinant proteins. In this chapter protocols for the expression and purification of both secreted and intracellular proteins using transient expression in HEK 293 cells are described.

The expression and purification of large amounts of recombinant protein complexes is an essential requirement for structural biology studies. For over two decades, prokaryotic expression systems such as E. coli have dominated the scientific literature over costly and less efficient eukaryotic cell lines. Despite the clear advantage in terms of yields and costs of expressing recombinant proteins in bacteria, the absence of specific co-factors, chaperones and post-translational modifications may cause loss of function, mis-folding and can disrupt protein-protein interactions of certain eukaryotic multi-subunit complexes, surface receptors and secreted proteins. The use of mammalian cell expression systems can address these drawbacks since they provide a eukaryotic expression environment. However, low protein yields and high costs of such methods have until recently limited their use for structural biology. Here we describe a simple and accessible method for expressing and purifying milligram quantities of protein by performing transient transfections of suspension grown HEK (Human Embryonic Kidney) 293 F cells.

Orthodontic tooth movement occurs as a result of resorption and formation of the alveolar bone due to an applied load, but the stimulus responsible for triggering orthodontic tooth movement remains the subject of debate. It has been suggested that the periodontal ligament (PDL) plays a key role. However, the mechanical function of the PDL in orthodontic tooth movement is not well understood as most mechanical models of the PDL to date have ignored the fibrous structure of the PDL. In this study we use finite element (FE) analysis to investigate the strains in the alveolar bone due to occlusal and orthodontic loads when PDL is modelled as a fibrous structure as compared to modelling PDL as a layer of solid material. The results show that the tension-only nature of the fibres essentially suspends the tooth in the tooth socket and their inclusion in FE models makes a significant difference to both the magnitude and distribution of strains produced in the surrounding bone. The results indicate that the PDL fibres have a very important role in load transfer between the teeth and alveolar bone and should be considered in FE studies investigating the biomechanics of orthodontic tooth movement.

Multi-body dynamics is a powerful engineering tool which is becoming increasingly popular for the simulation and analysis of skull biomechanics. This paper presents the first application of multi-body dynamics to analyse the biomechanics of the rabbit skull. A model has been constructed through the combination of manual dissection and three-dimensional imaging techniques (magnetic resonance imaging and micro-computed tomography). Individual muscles are represented with multiple layers, thus more accurately modelling muscle fibres with complex lines of action. Model validity was sought through comparing experimentally measured maximum incisor bite forces with those predicted by the model. Simulations of molar biting highlighted the ability of the masticatory system to alter recruitment of two muscle groups, in order to generate shearing or crushing movements. Molar shearing is capable of processing a food bolus in all three orthogonal directions, whereas molar crushing and incisor biting are predominately directed vertically. Simulations also show that the masticatory system is adapted to process foods through several cycles with low muscle activations, presumably in order to prevent rapidly fatiguing fast fibres during repeated chewing cycles. Our study demonstrates the usefulness of a validated multi-body dynamics model for investigating feeding biomechanics in the rabbit, and shows the potential for complementing and eventually reducing in vivo experiments.

Nuclear receptors are transcription factors that regulate gene expression through the ligand-controlled recruitment of a diverse group of proteins known as coregulators. Most nuclear receptor coregulators function in large multi-protein complexes that modify chromatin and thereby regulate the transcription of target genes. Structural and functional studies are beginning to reveal how these complexes are assembled bringing together multiple functionalities that mediate: recruitment to specific genomic loci through interaction with transcription factors; recruitment of enzymatic activities that either modify or remodel chromatin and targeting the complexes to their chromatin substrate. These activities are regulated by post-translational modifications, alternative splicing and small signalling molecules. This review focuses on our current understanding of coregulator complexes and aims to highlight the common principles that are beginning to emerge.

Sullom Voe Terminal has been in operation since November 1978, processing crude oil from the East Shetland Basin. Gas processing was initiated in April 1981, with full LPG production commencing in May 1982. The terminal is operated by BP Exploration, while port operations are controlled by Shetland Islands Council. This paper will summarise both terminal and port operations, to highlight those areas which involve a discharge or emission to the environment. Variation of the discharges with time will also be indicated to provide a background against which the results of the environmental monitoring programme can be set.

Histone deacetylase enzymes (HDACs) are emerging cancer drug targets. They regulate gene expression by removing acetyl groups from lysine residues in histone tails, resulting in chromatin condensation. The enzymatic activity of most class I HDACs requires recruitment into multi-subunit co-repressor complexes, which are in turn recruited to chromatin by repressive transcription factors. Here we report the structure of a complex between an HDAC and a co-repressor, namely, human HDAC3 with the deacetylase activation domain (DAD) from the human SMRT co-repressor (also known as NCOR2). The structure reveals two remarkable features. First, the SMRT-DAD undergoes a large structural rearrangement on forming the complex. Second, there is an essential inositol tetraphosphate molecule--D-myo-inositol-(1,4,5,6)-tetrakisphosphate (Ins(1,4,5,6)P(4))--acting as an 'intermolecular glue' between the two proteins. Assembly of the complex is clearly dependent on the Ins(1,4,5,6)P(4), which may act as a regulator--potentially explaining why inositol phosphates and their kinases have been found to act as transcriptional regulators. This mechanism for the activation of HDAC3 appears to be conserved in class I HDACs from yeast to humans, and opens the way to novel therapeutic opportunities.

Three-dimensional reconstructions of bone geometry from microCT (computed tomography) data are frequently used in biomechanical and finite element analyses. Digitization of bone models is usually a simple process for specimens with a complete geometry, but in instances of damage or disarticulation it can be very challenging. Subsequent to digitization, further imaging techniques are often required to estimate the geometry of missing bone or connecting cartilage. This paper presents an innovative approach to the reconstruction of incomplete scan data, to reproduce proper anatomical arrangements of bones, including absent connecting cartilaginous elements. Utilizing geometric morphometric tools, the reconstruction technique is validated through comparison of a reconstructed 9 year old pelvis, to the original CT data. A principal component analysis and an overlay of the two pelves provide a measure of the accuracy of the reconstructed model. Future work aims to investigate the biomechanical effects of any minor positional error on the bone's predicted structural properties through the use of finite element analysis.

Eukaryotic transcriptional repressors function by recruiting large co-regulatory complexes that target histone deacetylase enzymes to gene promoters/enhancers. Transcriptional repression complexes, assembled by the co-repressor NCoR, and its homologue SMRT, play critical roles in many processes including development and metabolic physiology. The core repression complex involves the recruitment of three proteins: HDAC3, GPS2 and TBL1 to a highly conserved repression domain within SMRT and NCoR. We have used a variety of structural and functional approaches to gain insight into the assembly, stoichiometry and biological role of this complex. We report the crystal structure of the tetrameric oligomerization domain of TBL1, which interacts with both SMRT and GPS2, and the NMR structure of the interface complex between GPS2 and SMRT. These structures, together with computational docking, mutagenesis and functional assays, reveal the assembly mechanism and stoichiometry of the co-repressor complex.

Hypernasality in velocardiofacial syndrome (VCFS) is more severe, persistent, and difficult to manage compared to other populations with cleft palate or velopharyngeal (VP) dysfunction. This pilot study investigated why children with VCFS have more severe hypernasality.Pressure-flow methodology indirectly measured VP orifice size and VP closure timing during speech in a group of 5 children with VCFS, 5 children with cleft palate, and 6 normal children.Children with VCFS demonstrated significant differences in VP closure timing and hypernasality. There were no significant group differences in VP orifice size. Duration of nasal airflow was the strongest predictor of judgments of hypernasality.This study provides preliminary evidence that VP closure timing may account for the more severe hypernasality in children with VCFS, compared to structural factors alone.

The retromer complex is responsible for the retrieval of mannose 6-phosphate receptors from the endosomal system to the Golgi. Here we present the crystal structure of the mammalian retromer subunit mVps29 and show that it has structural similarity to divalent metal-containing phosphoesterases. mVps29 can coordinate metals in a similar manner but has no detectable phosphoesterase activity in vitro, suggesting a unique specificity or function. The mVps29 and mVps26 subunits bind independently to mVps35 and together form a high-affinity heterotrimeric subcomplex. Mutagenesis reveals the structural basis for the interaction of mVps29 with mVps35 and subsequent association with endosomal membranes in vivo. A conserved hydrophobic surface distinct from the primary Vps35p binding site mediates assembly of the Vps29p-Vps26p-Vps35p subcomplex with sorting nexins in yeast, and mutation of either site results in a defect in retromer-dependent membrane trafficking.