Plant and algal chlorophyll synthases function in Synechocystis and interact with the YidC/Alb3 membrane insertase

In the model cyanobacteriumSynechocystissp. PCC 6803, the terminalenzyme of chlorophyll biosynthesis, chlorophyll synthase (ChlG), forms acomplex with high light-inducible proteins, the photosystem II assembly fac-tor Ycf39 and the YidC/Alb3/OxaI membrane insertase, co-ordinatingchlorophyll delivery with cotranslational insertion of nascent photosystempolypeptides into the membrane. To gain insight into the ubiquity of thisassembly complex in higher photosynthetic organisms, we produced functionalforeign chlorophyll synthases in a cyanobacterial host. Synthesis of algal andplant chlorophyll synthases allowed deletion of the otherwise essential nativecyanobacterial gene. Analysis of purified protein complexes shows that theinteraction with YidC is maintained for both eukaryotic enzymes, indicatingthat a ChlG-YidC/Alb3 complex may be evolutionarily conserved in algaeand plants

Residual cognitive deficits 50 years after lead poisoning during childhood

The long term neurobehavioural consequences of childhood lead poisoning are not known. In this study adult subjects with a documented history of lead poisoning before age 4 and matched controls were examined with an abbreviated battery of neuropsychological tests including measures of attention, reasoning, memory, motor speed, and current mood. The subjects exposed to lead were inferior to controls on almost all of the cognitive tasks. This pattern of widespread deficits resembles that found in children evaluated at the time of acute exposure to lead rather than the more circumscribed pattern typically seen in adults exposed to lead. Despite having completed as many years of schooling as controls, the subjects exposed to lead were lower in lifetime occupational status. Within the exposed group, performance on the neuropsychological battery and occupational status were related, consistent with the presumed impact of limitations in neuropsychological functioning on everyday life. The results suggest that many subjects exposed to lead suffered acute encephalopathy in childhood which resolved into a chronic subclinical encephalopathy with associated cognitive dysfunction still evident in adulthood. These findings lend support to efforts to limit exposure to lead in childhood

Probing the local lipid environment of the Rhodobacter sphaeroides cytochrome bc(1) and Synechocystis sp PCC 6803 cytochrome b(6)f complexes with styrene maleic acid

Intracytoplasmic vesicles (chromatophores) in the photosynthetic bacteriumRhodobacter sphaeroidesrepresent aminimal structural and functional unit for absorbing photons and utilising their energy for the generation ofATP. The cytochromebc1complex (cytbc1) is one of the four major components of the chromatophore alongsidethe reaction centre-light harvesting 1-PufX core complex (RC-LH1-PufX), the light-harvesting 2 complex (LH2),and ATP synthase. Although the membrane organisation of these complexes is known, their local lipid en-vironments have not been investigated. Here we utilise poly(styrene-alt-maleic acid) (SMA) co-polymers as a toolto simultaneously determine the local lipid environments of the RC-LH1-PufX, LH2 and cytbc1complexes. SMAhas previously been reported to effectively solubilise complexes in lipid-rich membrane regions whilst leavinglipid-poor ordered protein arrays intact. Here we show that SMA solubilises cytbc1complexes with an efficiencyof nearly 70%, whereas solubilisation of RC-LH1-PufX and LH2 was only 10% and 22% respectively. This highsusceptibility of cytbc1to SMA solubilisation is consistent with this complex residing in a locally lipid-richregion. SMA solubilised cytbc1complexes retain their native dimeric structure and co-purify with 56 ± 6phospholipids from the chromatophore membrane. We extended this approach to the model cyanobacteriumSynechocystissp. PCC 6803, and show that the cytochromeb6fcomplex (cytb6f) and Photosystem II (PSII)complexes are susceptible to SMA solubilisation, suggesting they also reside in lipid-rich environments. Thus,lipid-rich membrane regions could be a general requirement for cytbc1/cytb6fcomplexes, providing a favourablelocal solvent to promote rapid quinol/quinone binding and release at the Q0and Qisites

The outer halos of elliptical galaxies

Recent progress is summarized on the determination of the density distributions of stars and dark matter, stellar kinematics, and stellar population properties, in the extended, low surface brightness halo regions of elliptical galaxies. With integral field absorption spectroscopy and with planetary nebulae as tracers, velocity dispersion and rotation profiles have been followed to ~4 and ~5-8 effective radii, respectively, and in M87 to the outer edge at ~150 kpc. The results are generally consistent with the known dichotomy of elliptical galaxy types, but some galaxies show more complex rotation profiles in their halos and there is a higher incidence of misalignments, indicating triaxiality. Dynamical models have shown a range of slopes for the total mass profiles, and that the inner dark matter densities in ellipticals are higher than in spiral galaxies, indicating earlier assembly redshifts. Analysis of the hot X-ray emitting gas in X-ray bright ellipticals and comparison with dynamical mass determinations indicates that non-thermal components to the pressure may be important in the inner ~10 kpc, and that the properties of these systems are closely related to their group environments. First results on the outer halo stellar population properties do not yet give a clear picture. In the halo of one bright galaxy, lower [alpha/Fe] abundances indicate longer star formation histories pointing towards late accretion of the halo. This is consistent with independent evidence for on-going accretion, and suggests a connection to the observed size evolution of elliptical galaxies with redshift.Comment: 8 pages. Invited review to appear in the proceedings of "Galaxies and their Masks" eds. Block, D.L., Freeman, K.C. & Puerari, I., 2010, Springer (New York

Current status of turbulent dynamo theory: From large-scale to small-scale dynamos

Several recent advances in turbulent dynamo theory are reviewed. High resolution simulations of small-scale and large-scale dynamo action in periodic domains are compared with each other and contrasted with similar results at low magnetic Prandtl numbers. It is argued that all the different cases show similarities at intermediate length scales. On the other hand, in the presence of helicity of the turbulence, power develops on large scales, which is not present in non-helical small-scale turbulent dynamos. At small length scales, differences occur in connection with the dissipation cutoff scales associated with the respective value of the magnetic Prandtl number. These differences are found to be independent of whether or not there is large-scale dynamo action. However, large-scale dynamos in homogeneous systems are shown to suffer from resistive slow-down even at intermediate length scales. The results from simulations are connected to mean field theory and its applications. Recent work on helicity fluxes to alleviate large-scale dynamo quenching, shear dynamos, nonlocal effects and magnetic structures from strong density stratification are highlighted. Several insights which arise from analytic considerations of small-scale dynamos are discussed.Comment: 36 pages, 11 figures, Spa. Sci. Rev., submitted to the special issue "Magnetism in the Universe" (ed. A. Balogh

Fruit production, migrant bird visitation, and seed dispersal of Guarea glabra in Panama

The relationship between bird visitation and the size of the available fruit crop was studied at an understory tree ( Guarea glabra Vahl, Meliaceae) in the tropical wet forest of Barro Colorado Island, Panama Canal Zone. Twelve resident species and seven North American migrant species fed on the Bright orange arilloids (seeds with arils), which were not depleted during the normal fruiting period. The number of individual visitors, the number of visiting species, and the number of seeds removed increased linearly with the size of the available fruit crop. The proportion of seeds removed did not increase with the size of the available fruit crop, indicating that dispersal is a function of the number of fruit available and not a disproportionate function of large fruit displays. Four species of North American migrants ( Myiarchus crinitus, Catharus ustulatus, Vireo olivaceus , and Vermivora peregrina ) accounted for 70% of the visits and 60% of the seeds removed from the trees. No resident species visited Guarea as frequently as any one of these migrants. There was no indication that any single visitor was dependent on this tree for nutrition, nor that the tree was dependent upon any single species for dispersal. We hypothesize that the fruiting season of G. glabra is adaptively synchronized with northward migration of opportunistically frugivorous North American birds.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/47724/1/442_2004_Article_BF00348067.pd

From the outside in: narratives of creative arts practitioners working in the criminal justice system

This is an accepted manuscript of an article published by Wiley-Blackwell in The Howard Journal of Crime and Justice on 31/12/2019, available online: https://doi.org/10.1111/hojo.12318 The accepted version of the publication may differ from the final published version.The penal voluntary sector is highly variegated in its roles, practices and functions, though research to date has largely excluded the experiences of front-line practitioners. We argue that engaging with the narratives of practitioners can provide fuller appreciation of the potential of the sector’s work. Though life story and narrative have been recognised as important in offender desistance (Maruna, 2001), the narrative identities of creative arts practitioners, who are important ‘change agents’ (Albertson, 2015), are typically absent. This is despite evidence to suggest that a practitioner’s life history can be a significant and positive influence in the rehabilitation of offenders (Harris, 2017). Using narratological analysis (Bal, 2009), this study examined the narratives of 19 creative practitioners in prisons in England and Wales. Of particular interest were the formative experiences of arts practitioners in their journey to prison work. The findings suggest that arts practitioners identify with an ‘outsider’ status and may be motivated by an ethic of mutual aid. In the current climate of third sector involvement in the delivery of criminal justice interventions, such a capacity may be both a strength and weakness for arts organisations working in this field