Knock-Out of the Genes Coding for the Rieske Protein and the ATP-Synthase δ-Subunit of Arabidopsis

In Arabidopsis, the nuclear genes PetC and AtpD code for the Rieske protein of the cytochrome b6/f (cyt b6/f) complex and the δ-subunit of the chloroplast ATP synthase (cpATPase), respectively. Knock-out alleles for each of these loci have been identified. Greenhouse-grown petc-2 and atpd-1 mutants are seedling lethal, whereas heterotrophically propagated plants display a high-chlorophyll (Chl)-fluorescence phenotype, indicating that the products of PetC and AtpD are essential for photosynthesis. Additional effects of the mutations in axenic culture include altered leaf coloration and increased photosensitivity. Lack of the Rieske protein affects the stability of cyt b6/f and influences the level of other thylakoid proteins, particularly those of photosystem II. In petc-2, linear electron flow is blocked, leading to an altered redox state of both the primary quinone acceptor QA in photosystem II and the reaction center Chl P700 in photosystem I. Absence of cpATPase-δ destabilizes the entire cpATPase complex, whereas residual accumulation of cyt b6/f and of the photosystems still allows linear electron flow. In atpd-1, the increase in non-photochemical quenching of Chl fluorescence and a higher de-epoxidation state of xanthophyll cycle pigments under low light is compatible with a slower dissipation of the transthylakoid proton gradient. Further and clear differences between the two mutations are evident when mRNA expression profiles of nucleus-encoded chloroplast proteins are considered, suggesting that the physiological states conditioned by the two mutations trigger different modes of plastid signaling and nuclear response

TOWARDS A DATA MODEL FOR PLM APPLICATION IN BIO-MEDICAL IMAGING

International audienceBio-Medical Imaging (BMI) is currently confronted to data issues similar to those of the manufacturing industry twenty years ago. In particular, the need for data sharing and reuse has never been so strong to foster major discoveries in neuroimaging. Some data management systems have been developed to meet the requirements of BMI large-scale research studies. However, many efforts to integrate the data provenance along a research study, from the specifications to the published results, are to be done. Product Lifecycle Management (PLM) systems are designed to comply with manufacturing industry expectations of providing the right information at the right time and in the right context. Consequently PLM systems are proposed to be relevant for the management of BMI data. From a need analysis led with the GIN research group, the BMI-LM data model is designed: it is PLM-oriented, generic (enabling the management of many types of data such as imaging, clinical, psychology or genetics), flexible (enabling users’ customisation) and it covers the whole stages of a BMI study from specifications to publication. The test implementation of the BMI-LM model into a PLM system is detailed. The preliminary feed-back of the GIN researchers is discussed in this paper: the BMI-LM data model and the PLM concepts are relevant to manage BMI data, but PLM systems interfaces are unsuitable for BMI researchers

The invisible businessman: Nuclear physics, patenting practices,and trading activities in the 1930s

In the 1930s the production of patents for the protection of intellectual rights became central to the research activities of Enrico Fermi and his group, consistently with a research policy emerging within the Italian Fascist Regime. Behind their work was an international network consisting of businessmen, industrialists, and multinationals who helped them patent their method for the production of artificial radioactive elements and to promote its industrial exploitation. The lack of research funding combined with a more aggressive foreign policy of the regime made it impossible for the group to continue these activities in Rome, and in 1938 the promulgation of racial laws forced them to migrate abroad

Spectral signatures of photosynthesis I: Review of Earth organisms

Why do plants reflect in the green and have a 'red edge' in the red, and should extrasolar photosynthesis be the same? We provide: 1) a brief review of how photosynthesis works; 2) an overview of the diversity of photosynthetic organisms, their light harvesting systems, and environmental ranges; 3) a synthesis of photosynthetic surface spectral signatures; 4) evolutionary rationales for photosynthetic surface reflectance spectra with regard to utilization of photon energy and the planetary light environment. Given the surface incident photon flux density spectrum and resonance transfer in light harvesting, we propose some rules with regard to where photosynthetic pigments will peak in absorbance: a) the wavelength of peak incident photon flux; b) the longest available wavelength for core antenna or reaction center pigments; and c) the shortest wavelengths within an atmospheric window for accessory pigments. That plants absorb less green light may not be an inefficient legacy of evolutionary history, but may actually satisfy the above criteria.Comment: 69 pages, 7 figures, forthcoming in Astrobiology March 200

Gamma and beta frequency oscillations in response to novel auditory stimuli: A comparison of human electroencephalogram (EEG) data with in vitro models

Investigations using hippocampal slices maintained in vitro have demonstrated that bursts of oscillatory field potentials in the gamma frequency range (30-80 Hz) are followed by a slower oscillation in the beta 1 range (12-20 Hz). In this study, we demonstrate that a comparable gamma-to-beta transition is seen in the human electroencephalogram (EEG) in response to novel auditory stimuli. Correlations between gamma and beta 1 activity revealed a high degree of interdependence of synchronized oscillations in these bands in the human EEG. Evoked (stimulus-locked) gamma oscillations preceded beta 1 oscillations in response to novel stimuli, suggesting that this may be analogous to the gamma-to-beta shift observed in vitro. Beta 1 oscillations were the earliest discriminatory responses to show enhancement to novel stimuli, preceding changes in the broad-band event-related potential (mismatch negativity). Later peaks of induced beta activity over the parietal cortex were always accompanied by an underlying gamma frequency oscillation as seen in vitro. A further analogy between in vitro and human recordings was that both gamma and beta oscillations habituated markedly after the initial novel stimulus presentation

A consistent analysis of (e,e'p) and (d,3He) experiments

The apparent discrepancy between spectroscopic factors obtained in (e,e'p) and (d,3He) experiments is investigated. This is performed first for 48Ca(e,e'p) and 48Ca(d,3He) experiments and then for other nuclei. It is shown that the discrepancy disappears if the (d,3He) experiments are re-analyzed with a non-local finite range DWBA analysis with a bound-state wave function that is obtained from (e,e'p) experiments.Comment: 23 pages, 7 figure

Cortical Terminations of the Inferior Fronto-Occipital and Uncinate Fasciculi: Anatomical Stem-Based Virtual Dissection

International audienceWe combined the neuroanatomists' approach of defining a fascicle as all fibers passing through its compact stem with diffusion-weighted tractography to investigate the cortical terminations of two association tracts, the inferior fronto-occipital fasciculus (IFOF) and the uncinate fasciculus (UF), which have recently been implicated in the ventral language circuitry. The aim was to provide a detailed and quantitative description of their terminations in 60 healthy subjects and to do so to apply an anatomical stem-based virtual dissection, mimicking classical post-mortem dissection, to extract with minimal a priori the IFOF and UF from tractography datasets. In both tracts, we consistently observed more extensive termination territories than their conventional definitions, within the middle and superior frontal, superior parietal and angular gyri for the IFOF and the middle frontal gyrus and superior, middle and inferior temporal gyri beyond the temporal pole for the UF. We revealed new insights regarding the internal organization of these tracts by investigating for the first time the frequency, distribution and hemispheric asymmetry of their terminations. Interestingly, we observed a dissociation between the lateral right-lateralized and medial left-lateralized fronto-occipital branches of the IFOF. In the UF, we observed a rightward lateralization of the orbito-frontal and temporal branches. We revealed a more detailed map of the terminations of these fiber pathways that will enable greater specificity for correlating with diseased populations and other behavioral measures. The limitations of the diffusion tensor model in this study are also discussed. We conclude that anatomical stem-based virtual dissection with diffusion tractography is a fruitful method for studying the structural anatomy of the human white matter pathways

3^3He Structure and Mechanisms of p3p^3He Backward Elastic Scattering

The mechanism of $p^3$He backward elastic scattering is studied. It is found that the triangle diagrams with the subprocesses $pd\to ^3$He$\pi^0$, $pd^*\to ^3$He$\pi^0$ and $p(pp)\to^3$He$\pi^+$, where $d^*$ and $pp$ denote the singlet deuteron and diproton pair in the $^1S_0$ state, respectively, dominate in the cross section at 0.3-0.8 GeV, and their contribution is comparable with that for a sequential transfer of a $np$ pair at 1-1.5 GeV. The contribution of the $d^*+pp$, estimated on the basis of the spectator mechanism of the $p(NN)\to ^3$He$\pi$ reaction, increases the $p^3$He$\to ^3$He$p$ cross section by one order of magnitude as compared to the contribution of the deuteron alone. Effects of the initial and final states interaction are taken into account.Comment: 17 pages, Latex, 4 postscript figures, expanded version, accepted by Physical Review