Mutations in copper-zinc superoxide dismutase that cause amyotrophic lateral sclerosis alter the zinc binding site and the redox behavior of the protein.

A series of mutant human and yeast copper-zinc superoxide dismutases has been prepared, with mutations corresponding to those found in familial amyotrophic lateral sclerosis (ALS; also known as Lou Gehrig's disease). These proteins have been characterized with respect to their metal-binding characteristics and their redox reactivities. Replacement of Zn2+ ion in the zinc sites of several of these proteins with either Cu2+ or Co2+ gave metal-substituted derivatives with spectroscopic properties different from those of the analogous derivative of the wild-type proteins, indicating that the geometries of binding of these metal ions to the zinc site were affected by the mutations. Several of the ALS-associated mutant copper-zinc superoxide dismutases were also found to be reduced by ascorbate at significantly greater rate than the wild-type proteins. We conclude that similar alterations in the properties of the zinc binding site can be caused by mutations scattered throughout the protein structure. This finding may help to explain what is perhaps the most perplexing question in copper-zinc superoxide dismutase-associated familial ALS-i.e., how such a diverse set of mutations can result in the same gain of function that causes the disease.

Expression of calbindin-D28K in motoneuron hybrid cells after retroviral infection with calbindin-D28K cDNA prevents amyotrophic lateral sclerosis IgG-mediated cytotoxicity.

Calbindin-D28K and/or parvalbumin appear to influence the selective vulnerability of motoneurons in amyotrophic lateral sclerosis (ALS). Their immunoreactivity is undetectable in motoneurons readily damaged in human ALS, and in differentiated motoneuron hybrid cells [ventral spinal cord (VSC 4.1 cells)] that undergo calcium-dependent apoptotic cell death in the presence of ALS immunoglobulins. To provide additional evidence for the role of calcium-binding proteins in motoneuron vulnerability, VSC 4.1 cells were infected with a retrovirus carrying calbindin-D28K cDNA under the control of the promoter of the phosphoglycerate kinase gene. Differentiated calbindin-D28K cDNA-infected cells expressed high calbindin-D28K and demonstrated increased resistance to ALS IgG-mediated toxicity. Treatment with calbindin-D28K antisense oligodeoxynucleotides, which significantly decreased calbindin-D28K expression, rendered these cells vulnerable again to ALS IgG toxicity.

A gain-of-function of an amyotrophic lateral sclerosis-associated Cu,Zn-superoxide dismutase mutant: An enhancement of free radical formation due to a decrease in Km for hydrogen peroxide.

Cu,Zn-superoxide dismutase (SOD) is known to be a locus of mutation in familial amyotrophic lateral sclerosis (FALS). Transgenic mice that express a mutant Cu,Zn-SOD, Gly-93--> Ala (G93A), have been shown to develop amyotrophic lateral sclerosis (ALS) symptoms. We cloned the FALS mutant, G93A, and wild-type cDNA of human Cu,Zn-SOD, overexpressed them in Sf9 insect cells, purified the proteins, and studied their enzymic activities for catalyzing the dismutation of superoxide anions and the generation of free radicals with H2O2 as substrate. Our results showed that both enzymes contain one copper ion per subunit and have identical dismutation activity. However, the free radical-generating function of the G93A mutant, as measured by the spin trapping method, is enhanced relative to that of the wild-type enzyme, particularly at lower H2O2 concentrations. This is due to a small, but reproducible, decrease in the value of Km for H2O2 for the G93A mutant, while the kcat is identical for both enzymes. Thus, the ALS symptoms observed in G93A transgenic mice are not caused by the reduction of Cu,Zn-SOD activity with the mutant enzyme; rather, it is induced by a gain-of-function, an enhancement of the free radical-generating function. This is consistent with the x-ray crystallographic studies showing the active channel of the FALS mutant is slightly larger than that of the wild-type enzyme; thus, it is more accessible to H2O2. This gain-of-function, in part, may provide an explanation for the association between ALS and Cu,Zn-SOD mutants.

Transgenic mice carrying a human mutant superoxide dismutase transgene develop neuronal cytoskeletal pathology resembling human amyotrophic lateral sclerosis lesions.

Mutations in the human Cu,Zn superoxide dismutase gene (SOD1) are found in 20% of kindreds with familial amyotrophic lateral sclerosis. Transgenic mice (line G1H) expressing a human SOD1 containing a mutation of Gly-93 --> Ala (G93A) develop a motor neuron disease similar to familial amyotrophic lateral sclerosis, but transgenic mice (line N1029) expressing a wild-type human SOD1 transgene do not. Because neurofilament (NF)-rich inclusions in spinal motor neurons are characteristic of amyotrophic lateral sclerosis, we asked whether mutant G1H and/or N1029 mice develop similar NF lesions. NF inclusions (i.e., spheroids, Lewy body-like inclusions) were first detected in spinal cord motor neurons of the G1H mice at 82 days of age about the time these mice first showed clinical evidence of disease. Other neuronal intermediate filament proteins (alpha-internexin, peripherin) also accumulated in these spheroids. The onset of accumulations of ubiquitin immunoreactivity in the G1H mice paralleled the emergence of vacuoles and NF-rich spheroids in neurons, but they did not colocalize exclusively with spheroids. In contrast, NF inclusions were not seen in the N1029 mice until they were 132 days old, and ubiquitin immunoreactivity was not increased in the N1029 mice even at 199 days of age. Astrocytosis in spinal cord was associated with a marked increase in glial fibrillary acidic protein immunoreactivity in the G1H mice, but not in the N1029 mice. Finally, comparative studies revealed a striking similarity between the cytoskeletal pathology in the G1H transgenic mice and in patients with amyotrophic lateral sclerosis. These findings link a specific SOD1 mutation with alterations in the neuronal cytoskeleton of patients with amyotrophic lateral sclerosis. Thus, neuronal cytoskeletal abnormalities may be implicated in the pathogenesis of human familial amyotrophic lateral sclerosis.

Pars triangularis asymmetry and language dominance.

The pars triangular is a portion of Broca's area. The convolutions that form the inferior and caudal extent of the pars triangularis include the anterior horizontal and anterior ascending rami of the sylvian fissure, respectively. To learn if there are anatomic asymmetries of the pars triangularis, these convolutions were measured on volumetric magnetic resonance imaging scans of 11 patients who had undergone selective hemispheric anesthesia (Wada testing) to determine hemispheric speech and language lateralization. Of the 10 patients with language lateralized to the left hemisphere, 9 had a leftward asymmetry of the pars triangularis. The 1 patient with language lateralized to the right hemisphere had a significant rightward asymmetry of the pars triangularis. Our data suggest that asymmetries of the pars triangularis may be related to speech-language lateralization.

Blockade of action potential activity alters initial arborization of thalamic axons within cortical layer 4.

In the formation of connections during the development of the nervous system, it is generally accepted that there is an early phase not requiring neural activity and a later activity-dependent phase. The initial processes of axonal pathfinding and target selection are not thought to require neural activity, whereas the later fine-tuning of connections into their final adult patterns does. We report an apparent exception to this rule in which action potential activity seems to be required very early in development for thalamic axons to form appropriate patterns of terminal arborizations with their ultimate target neurons in layer 4 of the cerebral cortex. Blockade of sodium action potentials during the 2-week fetal period when visual thalamic axons initially grow into the primary visual cortex in cats prevents the normally occurring branching of lateral geniculate nucleus axons within layer 4. This observation implies a role for action-potential activity in cerebral cortical development far earlier than previously suspected, weeks before eye-opening and the onset of the well-known process of activity-dependent reorganization of axonal terminal arbors that leads to the formation of ocular dominance columns.

Dominance of one bacterial phylotype at a Mid-Atlantic Ridge hydrothermal vent site.

Microbial community structure in natural environments has remained largely unexplored yet is generally considered to be complex. It is shown here that in a Mid-Atlantic Ridge hydrothermal vent habitat, where food webs depend on prokaryotic primary production, the surface microbial community consists largely of only one bacterial phylogenetic type (phylotype) as indicated by the dominance of a single 16S rRNA sequence. The main part of its population occurs as an ectosymbiont on the dominant animals, the shrimp Rimicaris exoculata, where it grows as a monoculture within the carapace and on the extremities. However, the same bacteria are also the major microbial component of the free-living substrate community. Phylogenetically, this type forms a distinct branch within the epsilon-Proteobacteria. This is different from all previously studied chemoautotrophic endo- and ectosymbioses from hydrothermal vents and other sulfidic habitats in which all the bacterial members cluster within the gamma-Proteobacteria.

Control of somite patterning by signals from the lateral plate.

The body musculature of higher vertebrates is composed of the epaxial muscles, associated with the vertebral column, and of the hypaxial muscles of the limbs and ventro-lateral body wall. Both sets of muscles arise from different cell populations within the dermomyotomal component of the somite. Myogenesis first occurs in the medial somitic cells that will form the epaxial muscles and starts with a significant delay in cells derived from the lateral somitic moiety that migrate to yield the hypaxial muscles. The newly formed somite is mostly composed of unspecified cells, and the determination of somitic compartments toward specific lineages is controlled by environmental cues. In this report, we show that determinant signals for lateral somite specification are provided by the lateral plate. They result in a blockade of the myogenic program, which maintains the lateral somitic cells as undifferentiated muscle progenitors expressing the Pax-3 gene, and represses the activation of the MyoD family genes. In vivo, this mechanism could account for the delay observed in the onset of myogenesis between muscles of the epaxial and hypaxial domains.

The Lateral Trigger Probability function for the Ultra-High Energy Cosmic Ray showers detected by the Pierre Auger Observatory

In this paper we introduce the concept of Lateral Trigger Probability (LTP) function, i.e., the probability for an Extensive Air Shower (EAS) to trigger an individual detector of a ground based array as a function of distance to the shower axis, taking into account energy, mass and direction of the primary cosmic ray. We apply this concept to the surface array of the Pierre Auger Observatory consisting of a 1.5 km spaced grid of about 1600 water Cherenkov stations. Using Monte Carlo simulations of ultra-high energy showers the LTP functions are derived for energies in the range between 10(17) and 10(19) eV and zenith angles up to 65 degrees. A parametrization combining a step function with an exponential is found to reproduce them very well in the considered range of energies and zenith angles. The LTP functions can also be obtained from data using events simultaneously observed by the fluorescence and the surface detector of the Pierre Auger Observatory (hybrid events). We validate the Monte Carlo results showing how LTP functions from data are in good agreement with simulations.

Variation in the expression of migratory activity in blackcap (Sylvia atricapilla); effects of the origin, environmental conditions, dominance and personalities

La migración es una respuesta a cambios estacionales del clima generando desplazamientos periódicos entre hábitats de cría y de invernada, permitiendo así el uso temporal de los recursos disponibles. La migración implica unos costes energéticos muy elevados, un aumento de la depredación potencial, variaciones ambientales y una disponibilidad de alimento impredecible a lo largo de la ruta migratoria; por lo que es una de las actividades más desafiantes de su ciclo vital. A pesar de ello, los beneficios de la migración compensan sus costes. La migración está programada genéticamente, siendo relativamente constante en su momento, distancia y dirección. Por otro lado, ambiente juega un papel predominante en algunas poblaciones, pudiendo modificar el comportamiento migratorio de una estrategia parcial o facultativa a un modo de vida sedentario. Con el fin de describir el origen y evolución del comportamiento migratorio en aves, se ha propuesto un “modelo de umbral” genético para determinar si un ave es migrante o sedentaria. Dentro de una variable continua (p.ej. la concentración de proteínas u hormonas), este modelo asume que existe una actividad migratoria subyacente implicada en su expresión génica. Este umbral divide cada variable en categorías dicotómicas que definen el fenotipo de un individuo. Los ejemplares sin actividad migratoria muestran valores por debajo de este umbral, siendo clasificados como sedentarios, mientras que los ejemplares migrantes muestran valores por encima del umbral definido. Los cambios de estrategia vital no dependen únicamente de la posición del umbral determinado genéticamente sino también de las variables ambientales, por lo que dichas variaciones deben ser añadidas al modelo. Este modelo de umbral ambiental predice que el carácter migratorio de los individuos situados en los extremos de distribución no se encuentra afectado por los factores ambientales, mientras que aquellos más próximos al umbral pueden más fácilmente cambiar su estrategia migratoria...

Tectono-sedimentary evolution of the ’Numidian Formation’ and Lateral Facies (southern branch of the western Tethys): constraints for central-western Mediterranean geodynamics

The origin of the Numidian Formation (latest Oligocene to middle Miocene), characterized by ultra-mature quartzose arenites with abundant well-rounded frosted quartz grains, remains controversial. This formation, sedimented in the external domain of the Maghrebian Flysch Basin, displays three characteristic stratigraphic members with marked longitudinal (proximal–distal) and transverse (along-chain) variations with palaeogeographical importance. The origin of the Numidian supply is related to the outward tectogenetic propagation when a forebulge evolved in the African foreland, leading to the erosion of African cratonic areas rich in quartzose arenites (Nubian Sandstone-like). The ages of the Numidian Formation checked by Betic, Maghrebian and Southern Apennine data suggest a timing for the accretionary orogenic wedge, earlier in the Betic-Rifian Arc (after middle Burdigalian), later in the Algerian-Tunisian Tell (after late Burdigalian) and afterwards in Sicily and the Southern Apennines (after Langhian). A geodynamic evolutionary model for the central-western Mediterranean is proposed.

The functional significance of the hypocercal tail and lateral fin fold of Anaspid ostracoderms / James A. Hopson --.

v.33:no.5(1974)

Shifting Between Hegemony and Dominance? A Neo-Gramscian Analysis of the EU as a Structural Foreign Policy Actor: The Singular Case of the Cariforum-EU Economic Partnership Agreement. Bruges Regional Integration & Global Governance Paper 01/2014

The groundbreaking scope of the Economic Partnership Agreement (EPA) between the European Union (EU) and Cariforum (CF) irrefutably marks a substantive shift in trade relations between the regions and also has far-reaching implications across several sectors and levels. Supplementing the framework of analysis of Structural Foreign Policy (SFP) with neo-Gramscian theory allows for a thorough investigation into the details of structural embeddedness based on the EU's historic directionality towards the Caribbean region; notably, encouraging integration into the global capitalist economy by adapting to and adopting the ideals of neoliberal economics. Whilst the Caribbean – as the first and only signatory of a ‘full’ EPA – may be considered the case par excellence of the success of the EPAs, this paper demonstrates that there is no cause-effect relationship between the singular case of the ‘full’ CF-EU EPA and the success of the EPA policy towards the ACP in general. The research detailed throughout this paper responds to two SFP-based questions: (1) To what extent is the EPA a SFP tool aimed at influencing and shaping the structures in the Caribbean? (2) To what extent is the internalisation of this process reflective of the EU as a hegemonic SFP actor vis-à-vis the Caribbean? This paper affirms both the role of the EU as a hegemonic SFP actor and the EPA as a hegemonic SFP tool. Research into the negotiation, agreement and controversy that surrounds every stage of the EPA confirmed that through modern diplomacy and an evolution in relations, consensus is at the fore of contemporary EU-Caribbean relations. Whilst at once dealing with the singular case of the Caribbean, the author offers a nuanced approach beyond 'EU navel-gazing' by incorporating an ‘outside-in’ perspective, which thereafter could be applied to EU-ACP relations and the North-South dialogue in general.