Optimization of Nanoparticle-Based SERS Substrates through Large-Scale Realistic Simulations

Surface-enhanced Raman scattering (SERS) has become a widely used spectroscopic technique for chemical identification, providing unbeaten sensitivity down to the singlemolecule level. The amplification of the optical near field produced by collective electron excitations plasmons in nanostructured metal surfaces gives rise to a dramatic increase by many orders of magnitude in the Raman scattering intensities from neighboring molecules. This effect strongly depends on the detailed geometry and composition of the plasmonsupporting metallic structures. However, the search for optimized SERS substrates has largely relied on empirical data, due in part to the complexity of the structures, whose simulation becomes prohibitively demanding. In this work, we use state-of-the-art electromagnetic computation techniques to produce predictive simulations for a wide range of nanoparticle-based SERS substrates, including realistic configurations consisting of random arrangements of hundreds of nanoparticles with various morphologies. This allows us to derive rules of thumb for the influence of particle anisotropy and substrate coverage on the obtained SERS enhancement and optimum spectral ranges of operation. Our results provide a solid background to understand and design optimized SERS substrates.Peer ReviewedPostprint (published version

Enabling conditions for the implementation and conservation outcomes of a private nature reserve

Expanding conservation efforts to private land is paramount to halt biodiversity loss and achieve global conservation targets. Individual landowners can play disproportionately important roles by establishing private parks and managing them with biodiversity‐focused objectives. However, several constraints hinder the expansion of such initiatives, and little is known about their extent, characteristics and keys for success.Here, we provide insights on the conditions that favoured the establishment and conservation outcomes of a private reserve in central Spain whose management has been fully conservation‐oriented for the past two decades. We report on the actions implemented to accomplish four key targets that aimed at protecting and enhancing wildlife populations, and on the landholder's motivations to devote his personal resources to pursue this goal.The landholder suggests that public policy should reduce the bureaucratic burden to intrinsically motivated landowners and provide them technical advice, trust and financial incentives to expand conservation on private land.Ministerio de Asuntos Económicos y Transformación DigitalMinisterio de Ciencia e InnovaciónMinisterio de Educación, Cultura y DeporteComunidad de Madri

L-DOPA Treatment Selectively Restores Spine Density in Dopamine Receptor D2–Expressing Projection Neurons in Dyskinetic Mice

L-3,4-dihydroxyphenylalanine (L-DOPA)–induced dyskinesia is an incapacitating complication of L-DOPA therapy that affects most patients with Parkinson’s disease. Previous work indicating that molecular sensitization to dopamine receptor D1 (D1R) stimulation is involved in dyskinesias prompted us to perform electrophysiological recordings of striatal projection “medium spiny neurons” (MSN). Wild-type and bacterial artificial chromosome transgenic mice (D1R and D2R) mice were lesioned with 6-hydroxydopamine and then treated with L-DOPA. Functional, molecular, and structural changes were assessed in corticostriatal slices. Individual MSNs injected with Lucifer-Yellow were detected by immunohistochemistry for three-dimensional reconstructions. Both D1R-MSNs and D2R-MSNs showed diminished spine density in totally denervated striatal regions in parkinsonian mice. Chronic L-DOPA treatment, which induced dyskinesia and aberrant FosB expression, restored spine density in D2R-MSNs but not in D1R- MSNs. In basal conditions, MSNs are more excitable in parkinsonian than in sham mice, and excitability decreases toward normal values after L-DOPA treatment. Despite this normalization of basal excitability, in dyskinetic mice, the selective D1R agonist SKF38393 increased the number of evoked action potentials in MSNs, compared with sham animals. Conclusions: Chronic L-DOPA induces abnormal spine re-growth exclusively in D2R-MSNs and robust supersensitization to D1R- activated excitability in denervated striatal MSNs. These changes might constitute the anatomical and electrophysiological substrates of dyskinesia.This work was supported by grants from the Spanish Ministries de Economía y Competitividad and Sanidad y Política Social, ISCIII: BFU2010-20664, PNSD, RedRTA (RD06/0001/1011), CIBERNED ref.CB06/05/0055, and Comunidad de Madrid ref. S2011/BMD-2336 to RM; Spanish Ministries de Ciencia e Innovación (MICINN) PIU081067 to JMS Fondo Nacional para la Investigación Científica y Tecnológ- ica, Argentina, PICT 2008-2205/PICT 2011-521, Consejo Nacional de Investigaciones Científicas y Tecnológicas, Argentina, PIP 2009-77, and Universidad de Buenos Aires, UBACYT M562, to MGM

The early life history transitions of the bivalve aulacomya atra from the humboldt current system off peru are affected by human exploitation and modulated by El niño-la niña cycle

Understanding the factors and mechanisms that control temporal changes of larval settlement and subsequent recruitment of marine bivalves have strong implications for the management of exploited populations of coastal species and the conservation of benthic communities. Therefore, assessing both organismal and environmental drivers of the reproductive function, gamete release and recruitment is important. This is particularly true for highly productive upwelling coastal areas that are heavily affected by shifts in climatic regimes during the El Niño (EN)-La Niña (LN) cycle. We aimed to assess temporal variation in the transition between gamete release, larval settlement and subsequent recruitment of the commercially- important ribbed mussel (Aulacomya atra) at Bahía Independencia (Peru) over 9 years (1996-2004) - a period that covered strong EN and LN episodes. We also evaluate the environmental factors implied in these changes. To achieve this, we monitored monthly changes of the spawning stock biomass (SSB; a proxy of the capacity for propagule production and release), the number of settled postlarvae on artificial collectors, the density of recruits of A. atra and several environmental parameters. Our results showed a persistent trend of decreasing SSB and recruitment density, most likely related to human exploitation that reduced the population density by one order of magnitude. The SSB was a significant predictor of the number of settled postlarvae, regardless of the occurrence of EN or LN episodes. In contrast, the relationship between SSB and the density of recruits was dependent on the occurrence of EN or LN. The SSB and the larval settlement were heavily reduced during the warm EN in 1997-1998, presumably as a typical response of species of Antarctic origin to warmer-nutrient depleted waters and disturbed circulation patterns within the bay that may favor offshore transport of larvae. Despite this, the density of recruits of A. atra was high during EN, presumably as a result of reduced competition for food and reduced predation, which may overcompensate for the mortality of recruits associated with thermal stress

Enhanced Production of Runaway Electrons during a Disruptive Termination of Discharges Heated with Lower Hybrid Power in the Frascati Tokamak Upgrade

4 pages, 4 figures.-- PACS nrs.: 52.55.Fa, 52.35.Py, 52.50.Sw, 52.55.Pi.We report on the observation of a large production of runaway electrons during a disruptive termination of discharges heated with lower-hybrid waves at the Frascati Tokamak Upgrade. The runaway current plateaus, which can carry up to 80% of the predisruptive current, are observed more often than in normal Ohmic disruptions. The largest runaway currents correspond to the slowest plasma current decay rates. This trend is opposite to what is observed in most tokamaks. We attribute this anomalous behavior to the acceleration of the preexistent wave-resonant suprathermal electrons during the disruption decay phase. These results could be relevant for the operation of the ITER tokamak whenever a sizeable amount of lower-hybrid power is made available.Research supported in part by Spanish DGES Project No. FTN2003-04587. This work was also supported by the Euratom Communities under the contract of association between EURATOM and ENEA.Publicad

Increased Cysteine Availability is Essential for Cadmium Tolerance and Accumulation in Arabidopsis Thaliana

Employing genetic transformation using an Atcys-3A cDNA construct expressing the cytosolic O-acetylserine(thiol)lyase (OASTL), we obtained two Arabidopsis lines with different capabilities for supplying cysteine under metal stress conditions. Lines 1-2 and 10-10, grown under standard conditions, showed similar levels of cysteine and glutathione (GSH) to those of the wild-type. However, in the presence of cadmium, line 10-10 showed significantly higher levels. The increased thiol content allowed line 10-10 to survive under severe heavy metal stress conditions (up to 400M of cadmium in the growth medium), and resulted in an accumulation of cadmium in the leaves to a level similar to that of metal hyperaccumulator plants. Investigation of the epidermal leaf surface clearly showed that most of the cadmium had accumulated in the trichomes. Furthermore, line 10-10 was able to accumulate more cadmium in its trichomes than the wild-type, whereas line 1-2 showed a reduced capacity for cadmium accumulation. Our results suggest that an increased rate of cysteine biosynthesis is responsible for the enhanced cadmium tolerance and accumulation in trichome leaves. Thus, molecular engineering of the cysteine biosynthesis pathway, together with modification of the number of leaf trichomes, may have considerable potential in increasing heavy metal accumulation for phytoremediation purposes.Dirección General de InvestigaciónJunta de Andalucí

Ancient origin of the CAG expansion causing Huntington disease in a Spanish population

25 p. Figuras, tablas, bibliografíaHuntington disease (HD, MIM# 143100) is an autosomal dominant neurodegenerative disorder characterized clinically by progressive motor impairment, cognitive decline, and emotional deterioration. The disease is caused by the abnormal expansion of a CAG trinucleotide repeat in the first exon of the huntingtin gene in chromosome 4p16.3. HD is spread worldwide and it is generally accepted that few mutational events account for the origin of the pathogenic CAG expansion in most populations. We have investigated the genetic history of HD mutation in 83 family probands from the Land of Valencia, Eastern Spain. An analysis of the HD/CCG repeat in informative families suggested that at least two main chromosomes were associated in the Valencian population, one associated with allele 7 (77 mutant chromosomes) and one associated with allele 10 (2 mutant chromosomes). Haplotype A-7-A (H1) was observed in 47 out of 48 phase-known mutant chromosomes, obtained by segregation analysis, through the haplotype analysis of rs1313770-HD/CCGrs82334, as it also was in 120 out of 166 chromosomes constructed by means of the PHASE program. The genetic history and geographical distribution of the main haplotype H1 were both studied by constructing extended haplotypes with flanking STRs D4S106 and D4S3034. We found that we were able to determine the age of the CAG expansion associated with the haplotype H1 as being between 4,700 and 10,000 years ago. Furthermore, we observed a nonhomogenous distribution in the different regions associated with the different extended haplotypes of the ancestral haplotype H1, suggesting that local founder effects have occurred.This work was supported by the Fondo de investigación Sanitaria (FIS grant 01/1159), the Instituto de Salud Carlos III (grant G03/56) for the Spanish Network on Cerebellar Ataxias, and the Generalitat Valenciana (grant GRUPOS03/015).Peer reviewe

Ancient origin of the CAG expansion causing Huntingtons disease in a Spanish population.

[EN] Huntington disease (HD) is an autosomal dominant neurodegenerative disorder characterized clinically by progressive motor impairment, cognitive decline, and emotional deterioration. The disease is caused by the abnormal expansion of a CAG trinucleotide repeat in the first exon of the huntingtin gene in chromosome 4p16.3. HD is spread worldwide and it is generally accepted that few mutational events account for the origin of the pathogenic CAG expansion in most populations. We have investigated the genetic history of HD mutation in 83 family probands from the Land of Valencia, in Eastern Spain. An analysis of the HD/CCG repeat in informative families suggested that at least two main chromosomes were associated in the Valencian population, one associated with allele 7 (77 mutant chromosomes) and one associated with allele 10 (two mutant chromosomes). Haplotype A-7-A (H1) was observed in 47 out of 48 phase-known mutant chromosomes, obtained by segregation analysis, through the haplotype analysis of rs1313770-HD/CCG-rs82334, as it also was in 120 out of 166 chromosomes constructed by means of the PHASE program. The genetic history and geographical distribution of the main haplotype H1 were both studied by constructing extended haplotypes with flanking short tandem repeats (STRs) D4S106 and D4S3034. We found that we were able to determine the age of the CAG expansion associated with the haplotype H1 as being between 4,700 and 10,000 years ago. Furthermore, we observed a nonhomogenous distribution in the different regions associated with the different extended haplotypes of the ancestral haplotype H1, suggesting that local founder effects have occurred.We are grateful for the kind collaboration of patients and families. This work was supported by the Fondo de investigación Sanitaria (FIS grant 01/1159), the Instituto de Salud Carlos III (grant G03/56) for the Spanish Network on Cerebellar Ataxias, and the Generalitat Valenciana (grant GRUPOS03/015).García-Planells, J.; Burguera, JA.; Solís, P.; Millán, JM.; Ginestar Peiro, D.; Palau, F.; Espinós-Armero, CÁ. (2005). Ancient origin of the CAG expansion causing Huntingtons disease in a Spanish population. Human Mutation. 25(5):453-459. https://doi.org/10.1002/humu.2016745345925

Integrating plasmonic supercrystals in microfluidics for ultrasensitive, label-free, and selective surface-enhanced raman spectroscopy detection

Surface-enhanced Raman spectroscopy (SERS) microfluidic chips for label-free and ultrasensitive detection are fabricated by integrating a plasmonic supercrystal within microfluidic channels. This plasmonic platform allows the uniform infiltration of the analytes within the supercrystal, reaching the so-called hot spots. Moreover, state-of-the-art simulations performed using large-scale supercrystal models demonstrate that the excellent SERS response is due to the hierarchical nanoparticle organization, the interparticle separation (IPS), and the presence of supercrystal defects. Proof-of-concept experiments confirm the outstanding performance of the microfluidic chips for the ultradetection of (bio)molecules with no metal affinity. In fact, a limit of detection (LOD) as low as 10–19 M was reached for crystal violet. The SERS microfluidic chips show excellent sensitivity in the direct analysis of pyocyanin secreted by Pseudomonas aeruginosa grown in a liquid culture medium. Finally, the further integration of a silica-based column in the plasmonic microchip provides charge-selective SERS capabilities as demonstrated for a mixture of positively and negatively charged molecules.Agencia Estatal de Investigación | Ref. TEC2017-85376-C2-1-RAgencia Estatal de Investigación | Ref. TEC2017-85376-C2-2-RXunta de Galicia | Ref. GRC ED431C 2016−486 048Gobierno de Extremadura | Ref. IB18073Agencia Estatal de Investigación | Ref. IJCI-2016-2910

Species delimitation using genomic data to resolve taxonomic uncertainties in a speciation continuum of pelagic seabirds

Speciation is a continuous and complex process shaped by the interaction of numerous evolutionary forces. Despite the continuous nature of the speciation process, the implementation of conservation policies relies on the delimitation of species and evolutionary significant units (ESUs). Puffinus shearwaters are globally distributed and threatened pelagic seabirds. Due to remarkable morphological status the group has been under intense taxonomic debate for the past three decades. Here, we use double digest Restriction-Site Associated DNA sequencing (ddRAD-Seq) to genotype species and subspecies of North Atlantic and Mediterranean Puffinus shearwaters across their entire geographical range. We assess the phylogenetic relationships and population structure among and within the group, evaluate species boundaries, and characterise the genomic landscape of divergence. We find that current taxonomies are not supported by genomic data and propose a more accurate taxonomy by integrating genomic information with other sources of evidence. Our results show that several taxon pairs are at different stages of a speciation continuum. Our study emphasises the potential of genomic data to resolve taxonomic uncertainties, which can help to focus management actions on relevant taxa, even if they do not necessarily coincide with the taxonomic rank of species