Regional brain susceptibility to neurodegeneration: what is the role of glial cells?

The main pathological feature of the neurodegenerative diseases is represented by neuronal death that represents the final step of a cascade of adverse/hostile events.Early in the neurodegenerative process,glial cells (including astrocytes,microglial cells,and oligodendrocytes) activate and trigger an insidious neuroinflammatory reaction,metabolic decay,blood brain barrier dysfunction and energy impairment,boosting neuronal death.How these mechanisms might induce selective neuronal death in specific brain areas are far from being elucidated.The last two decades of neurobiological studies have provided evidence of the main role of glial cells in most of the processes of the central nervous system,from development to synaptogenesis,neuronal homeostasis and integration into,highly specific neuro-glial networks.In this mini-review,we moved from in vitro and in vivo models of neurodegeneration to analyze the putative role of glial cells in the early mechanisms of neurodegeneration.We report changes of transcriptional,genetic,morphological,and metabolic activity in astrocytes and microglial cells in specific brain areas before neuronal degeneration,providing evidence in experimental models of neurodegenerative disorders,including Parkinson’s and Alzheimer’s diseases.Understanding these mechanisms might increase the insight of these processes and pave the way for new specific glia-targeted therapeutic strategies for neurodegenerative disorders.

Phytogenic Mounds (Nebkhas): Effect of Tricomaria usillo on Sand Entrapment in Central-West of Argentina

Nebkhas, developed by the trapping of sand within the body of a plant, were studied in the Médanos Grandes system, arid central Argentina, during the springs of 2009-2010. The dynamics of nebkhas was studied in three draas (megadunes), and considering both orientations: leeward and windward. The Drift Potential (DP) for the study area was 42, evidencing the inactivity of the sand dunes or the scarce activity only in crests. Dominant sand movement is in south-southeast direction, with deflation processes at the southern side of the nebkhas. All nebkhas showed uniformity in the morphometry. Tricomaria usillo is the dominant plant species in the nebkha formation process;and results showed a significant positive relationship between nebkha and canopy volumes.

Hydrological Controls on Nutrient Exportation from Old-Growth Evergreen Rainforests and <i>Eucalyptus nitens</i>Plantation in Headwater Catchments at Southern Chile

Soil cover disturbances have a direct effect on biogeochemistry, potentially enhancing nutrient loss, land degradation and associated changes in ecosystem services and livelihood support. The objective of this study was to assess how canopy affected throughfall chemistry and how hydrology affected stream nutrient load responses in two watersheds dominated by native old-growth evergreen rainforest (NF) and exotic plantation of Eucalyptus nitens (EP), located at the Coastal mountain range of southern Chile (40&deg;S). We measured nitrogen (NO3-N, NH4-N, Organic-N, Total-N) and total phosphorus (Total-P) at catchment discharge, and δ18O in throughfall precipitation and stream discharge in both catchments, in order to separate throughfall (or new water) contributions during storm events. It was hypothesized that all nutrients showed an increase in concentration as discharge increased (or enhanced hydrological access), in EP;but not in NF. Our results indicated that Organic-N, Total-N and Total-P concentrations were positively related to discharge. However, NO3<sup style="margin-left:-7px;">--N showed a negative correlation with catchment discharge. Organic-N and Total-P showed a flush during storm events;the opposite was observed for NO3<sup style="margin-left:-7px;">--N. However, this behavior suggested that NO3<sup style="margin-left:-7px;">--N was being retained by charged particles or soil micro biota, whether Organic-N was flushed as it was more concentrated in big pore water that was not tightly attached, compared with NO3<sup style="margin-left:-7px;">--N.

Anomalously deep earthquakes related to the Ojo de Agua Lineament and its tectonic significance,Sierras Pampeanas of Córdoba,Central Argentina

The Sierras de Cordoba are the easternmost uplifted ranges of the Sierras Pampeanas geological province of Argentina. They are composed of a Neoproterozoic-Paleozoic basement arranged in north-south aligned mountain ranges, limited by west-vergent reverse faults, reactivated or formed by compressive tectonics during the Andean orogeny. The ranges are also affected by oblique subvertical lineaments,probably related to pan-Gondwanan structures. The recorded seismicity shows anomalously deep earthquakes（up to 80 km depth） concentrated in the northwestern area. We attribute this seismicity to the current tectonic activity of the Ojo de Agua Lineament. This lineament is a N13°-135° strike, 70°-80° NE dip,macrostructure with more than 80 km depth and 160 km length. A sinistral transcompressional kinematics（convergent oblique shear） is deduced by the focal mechanism of a deep earthquake, together with hydrological and geomorphological features strongly modified. The continental lithosphere under the Sierras de Cordoba would be colder and more rigid than in a normal subduction area, due to the retraction of the asthenospheric wedge to the foreland, causing seismicity to depths greater than 40 km, below the Mohorovicic discontinuity. Neogene volcanism would be closely related to this lineament, allowing the rapid ascent of melts from the mantle.

Stripe of normal mechanisms for crustal earthquakes with M ≤ 3.5 flanking the western side of the thrust front zone in the Andes backarc

Earthquakes with magnitudes M ≤ 3.5 were registered in the Andes backarc between ~32.5°S 33.75°S within a temporary experiment from November 2002 to March 2003. Data were collected from 15 seismological broad band stations, deployed above flat subduction section and also above the transitional to normal section of the Nazca plate. Seismic events were located mostly in part of the Southern Precordillera and Cerrilladas Pedemontanas of Mendoza Province. Focal mechanism solutions were obtained, for selected data between15 kmand35 kmdepths, from P wave first motion using FOCMEC software. A band trending NW-NNW of normal focal mechanism earthquakes is located just by the thrust front towards West, and covers the Southern tip of the Southern Precordillera and the Western side of the Cerrilladas Pedemontanas, Mendoza Province, Argentina. Thrust focal mechanism solutions obtained in the present work for events with magnitude less than or equal to 3.5 also show that the thrust front South of ~33.1°S is located in the same place as Mw ≥ 3.6 earthquakes. The most significant findings in this work are these signals of extensional regimen which appear in a compressional subduction tectonic regimen. Nevertheless the short temporal experiment precludes firm interpretations about this particular phenomenon. Probably it is related to a temporary stress relaxation. The normal earthquakes are likely associated to normal faults, and/or to their subsidiaries, that were inverted by contraction and now re-inverted at least transitorily as normal. These faults, which are near and to the East of the suture between Chilenia and Cuyania Paleozoic terranes, were originally involved in the Cuyo Triassic basin formation.

Subtle sexual plumage color dimorphism and size dimorphism in a South American colonial breeder, the Monk Parakeet(Myiopsitta monachus)

Background:Parrots(Psittacidae Family)are one of the most colorful groups of birds in the world,their colors pro-duced both structurally and via unusual pigments(psittacofulvins).Most species are considered to be monogamous,and many have been viewed historically as sexually monomorphic and monochromatic.However,studies using morphometric analysis and spectrophotometric techniques have revealed sexual size dimorphism and also sexual plumage color dimorphism among some species.The Monk Parakeet(Myiopsitta monachus),a native parrot of South America,is an interesting species for the study of plumage coloration and size since it is considered sexually mono-chromatic and monomorphic.Furthermore,recent studies show that the Monk Parakeet has extra-bond paternity behavior and even breeding trios,which suggests that sexual selection may play an important role in this species,and that it might have sexually dimorphic plumage(albeit imperceptible by humans)and be dimorphic in size.Methods:For the determination of plumage color we used spectrophotometry in the range of avian vision(300-700 nm)and performed a morphological analysis.Results:Our spectrophotometric results indicate that the Monk Parakeet shows subtle sexual plumage color dimor-phism in three(crown,nape and wing)out of twelve body regions.Similarly,our morphometric analysis showed that there are subtle sex differences in body size(bill and weight).Conclusions:Although the Monk Parakeet shows extra-bond paternity and breeding trio behaviors which could increase sexual dimorphism,these behaviors occur among highly related individuals;perhaps the high rate of inbreeding is responsible for the attenuation of sexual plumage color dimorphism and sex differences in body size observed.

THERMAL PERFORMANCE OF AN EXTENSIVE GREEN ROOF UNDER SEMI-ARID CONDITIONS IN CENTRAL ARGENTINA

Extensive green roofs improve the provision of ecosystem services in urban environ-ments,particularly in semiarid regions.The aim of this paper is to compare their thermal performance during six months between two rooms,one with a green roof and the other with a conventional roof,in Córdoba(Argentina).The room with a green(planting)roof showed a lower inside surface temperature since the begin-ning of the study than the control room(between 5-6°C of difference).During the selected period,the indicators such as temperature amplitude(the difference between the maximum and the average temperature)and the anti-interference characteristics of the layers to the outdoor air temperature are produced a better performance for the green roof compared to the conventional roof.The pattern of a better perfor-mance was consistent across the study for the green roof,characterized by a higher cooling and warming of the roof surface during the day and night,respectively.The green roof was more effective at blocking an upward heat flux during the day and suppressing heat loss during the night.Evaporation,conductive flux and climatic conditions seem to dominate the thermal performance of green roofs in areas with semiarid climate conditions.

Mountain invasions on the way:are there climatic constraints for the expansion of alien woody species along an elevation gradient in Argentina?

Aims Increasing evidence worldwide indicates that high mountain regions are not immune to invasion by alien plants.Here,we aimed to address whether three major woody invaders of low-mountain areas are constrained to lower altitudes due to climatic restrictions or just by low propagule pressure.We hypothesize that the increasing climatic harshness towards higher altitudes restricts seedling establishment and survival of these woody invaders and thus their potential for altitudinal expansion.Methods The study was carried out in the Sierras Grandes Mountains,Córdoba,central Argentina(32°50′S,64°90′W).We addressed the hypothesis with an experimental approach,dissociating the effect of the environmental gradient from that of propagule pressure,by discarding the influence of seed sources.We translocated seeds of Gleditsia triacanthos L.,Ligustrum lucidum W.T.Aiton.and Pyracantha angustifolia(Franch.)C.K.Schneid.along the altitudinal gradient(from 900 to 2700 m asl).Seven sites were selected along the altitudinal gradient,spaced every 200-400 m.Three plots(4×4 m)were selected within each altitudinal site and excluded from livestock;100 seeds of each species were sown within each plot(6300 seeds in total).Seedling emergence and survival was monitored during two growing seasons and soil temperature and moisture was recorded as well.The field experiment was complemented with lab assays.Important Findings Climate along this altitudinal gradient might be least restrictive at mid elevations,as a result of the intersection between opposite soil temperature and moisture gradients.Sown seeds germinated along the whole altitudinal gradient and seedlings successfully established and over-wintered well above their current altitudinal distribution(up to 2200 m for Ligustrum and 2400 m for Gleditsia and Pyracantha).Additional lab assays confirmed field patterns and gave some insights into contrasting regeneration strategies between these invaders that might help to overcome stochastic environmental constraints in the germination stage.Overall,seedlings of three major woody invaders of low-mountain woodlands can establish and survive at higher elevations than their current distribution.In contrast to natives,they seem to be broad climate tolerators,rather than specialized stress tolerators,capable of germinating and growing across a wide elevational range.While long-term experiments might be necessary to fully address the potentials for altitudinal expansion,out results on early lifecycle stage suggest that the invaders studied here would have mostly a dispersal barrier rather than a climate barrier to establish in the upper belt of the Sierras Grandes.

Functional strategies and distribution of climbing plant communities in different vegetation patches in a subtropical dry forest, central Argentina

Aims In the context of global change,the impacts of forest structure alter-ation on climbing plants in extra-tropical ecosystems are poorly understood.It also remains little explored,the functional strategies among climbing plant species and its relationship with the local-scale distribution of climbing plant communities.Here,we aimed at three goals:(i)we studied how climbing plant community com-position responds to the modification of the original forest structure in a subtropical dry forest;(ii)we characterized climbing plant spe-cies according to functional traits related to the acquisition and use of resources;and(iii)we examined whether functional strategies at the community level are also responding to vegetation structure change,a much less addressed topic in the ecology of climbing plants.Methods The study was carried out in the Chaco forest of Córdoba Mountains,central Argentina.We selected 18 patches of‘native forests’,‘shrublands’and‘Ligustrum lucidum forests’.We counted and identified climbing plant individuals in each patch,including woody and herbaceous species.For each spe-cies,we measured 10 functional traits:leaf area,leaf area ratio,leaf dry matter content,leaf tensile strength,specific leaf area,stem density,wood saturated water content,inter-node length,petiole length and plant cover.We compared climbing plant composition,richness and abundance among the three vegeta-tion types.Then,we assessed trends of functional variation of climbing plant species by performing a principal component analysis.Finally,we investigated whether simple mean,weighted mean and Functional Richness index of principal component analysis(PCA)axes differed among the climbing plant communi-ties of the three vegetation types.Important Findings Multivariate analysis revealed that climbing plant composition of native forests significantly differed from that of shrublands and L.lucidum forests.Also,L.lucidum forests had the lowest climb-ing plant species richness.Functional variation of climbers was explained by three PCA axes:axis 1 represented the resource-use strategy,axis 2 was associated with light-foraging strategy,and axis 3 related to plant size.The most abundant species in native forests presented a more acquisitive functional strategy and larger sizes than those of shrublands and L.lucidum forest.Furthermore,the most abundant species in shrublands had shorter internodes and petioles than the most abundant climbers of the other vegeta-tion types.Finally,the climbing plant community in the native forests had the highest Functional Richness index regarding the resource-use and the size strategies.Here,we demonstrated that there are floristic and functional differences among climb-ing plant communities in patches of three vegetation types in a subtropical dry forest biome.Particularly,we found climbers spreading along three functional axes which were directly related to climbing plant community distribution among the different patches,highlighting their ecological importance and the need of further research.

Engineering a recombinant chlorotoxin as celltargeted cytotoxic nanoparticles

Cytotoxic proteins have a wide applicability in human therapies, especially in those conditions that require efficient and selective cell killing, such as cancer. Chlorotoxin (CTX) is a small (4 kDa) basic peptide from the venom of the yellow scorpion Leiurus quinquestriatus , which blocks small-conductance chloride channels thus paralyzing the scorpion prey. Being not extremely potent as a cytotoxin (for instance when compared with ribosome-inactivating proteins), it has gained interest as a targeting agent.