Facile production of stable silicon nanoparticles: laser chemistry coupled to in situ stabilization via room temperature hydrosilylation

Stable, alkyl-terminated, light-emitting silicon nanoparticles have been synthesized in a continuous process by laser pyrolysis of a liquid trialkyl-silane precursor selected as a safer alternative to gas silane (SiH4). Stabilization was achieved by in situ reaction using a liquid collection system instead of the usual solid state filtration. The alkene contained in the collection liquid (1-dodecene) reacted with the newly formed silicon nanoparticles in an unusual room-temperature hydrosilylation process. It was achieved by the presence of fluoride species, also produced during laser pyrolysis from the decomposition of sulfur hexafluoride (SF6) selected as a laser sensitizer. This process directly rendered alkyl-passivated silicon nanoparticles with consistent morphology and size (<3 nm), avoiding the use of costly post-synthetic treatments

What DNA barcodes reveal : microhabitat preference, hunting strategy and dispersal ability drive genetic variation across Iberian spider species

1. The current rate of species loss calls for immediate actions to preserve biodiversity and ecosystem functioning. Cataloguing species richness and composition, and revealing how diversity is geographically distributed are the first steps towards designing efficient conservation strategies. 2. Here, we aim to determine diversity patterns and potential drivers of taxonomic and genetic diversity and population structure of Iberian spiders. We used a community level perspective, analysing more than 3000 DNA barcode sequences representing similar to 370 spider species dwelling in white-oak forest habitats across the Spanish National Park network. 3. By combining and comparing morphological and DNA barcode-based species delimitation methods, we assessed their performance and identified putative factors behind cases of incongruence. Our findings uncovered potential overlooked diversity as suggested by the geographic patterns of genetic variation and put a red flag on those taxa that may be undergoing overlooked evolutionary or ecological processes. 4. Spider functional traits associated with foraging strategy, microhabitat preference, ballooning ability and circadian activity explained the observed patterns of population structure across species but did not explain variation in genetic diversity. Overall, our study represents a major step forward in the understanding of large-scale diversity patterns in Iberian spiders at the community level and provides relevant information to guide future conservation strategies of the so-far largely overlooked invertebrate diversity.Peer reviewe

For all audiences : Incorporating immature stages into standardised spider inventories has a major impact on the assessment of biodiversity patterns

Although arthropods are the largest component of animal diversity, they are traditionally underrepresented in biological inventories and monitoring programmes. However, no biodiversity assessment can be considered informative without including them. Arthropod immature stages are often discarded during sorting, despite frequently representing more than half of the collected individuals. To date, little effort has been devoted to characterising the impact of discarding nonadult specimens on our diversity estimates. Here, we used a metabarcoding approach to analyse spiders from oak forests in the Iberian Peninsula, to assess (1) the contribution of juvenile stages to local diversity estimates, and (2) their effect on the diversity patterns (compositional differences) across assemblages. We further investigated the ability of metabarcoding to inform on abundance. We obtained 363 and 331 species as adults and juveniles, respectively. Including the species represented only by juveniles increased the species richness of the whole sampling in 35% with respect to those identified from adults. Differences in composition between assemblages were greatly reduced when immature stages were considered, especially across latitudes, possibly due to phenological differences. Moreover, our results revealed that metabarcoding data are to a certain extent quantitative, but some sort of taxonomic conversion factor may be necessary to provide accurate informative estimates. Although our findings do not question the relevance of the information provided by adult-based inventories, they also reveal that juveniles provide a novel and relevant layer of knowledge that, especially in areas with marked seasonality, may influence our interpretations, providing more accurate information from standardised biological inventories.Peer reviewe

New contributions to the geographical distinction of painted andalusi plinths

[EN] Few examples remain of artistic Andalusi decoration in the form of painted plinths in residential settings. Several technological issues have arisen when noting potential connections in an attempt to contextualize the styles, geography and chronologies of these plinths. Using XRD, FTIR and stratigraphic analysis, and considering previous research, the study of execution techniques and materials observed in plinths in Baŷŷāna (Almería) has made it possible to establish parallels with decorated plinths from the Barrio de casas de la Alcazaba in Malaga. Based on these results, interesting conclusions can be drawn regarding production techniques which are in keeping with the survival of certain execution procedures of Roman origin for renderings. Furthermore, the existence of a production nucleus grouping the examples from Almería and Malaga is proposed within a technical context which would set them apart.[ES] Una manifestación artística de la decoración andalusí de la que se conservan escasos testimonios son los zócalos pintados en el ámbito doméstico. Los intentos por contextualizar estilística, geográfica y cronológicamente estos zócalos han planteado algunas cuestiones de índole tecnológica a la hora de apuntar posibles conexiones. El estudio de las técnicas de ejecución y materiales empleados en zócalos de Baŷŷāna (Almería), mediante análisis estratigráfico, DRX y FTIR, ha permitido establecer paralelismos con zócalos decorados procedentes del barrio de casas de la Alcazaba de Málaga a partir de una investigación anterior. Los resultados permiten extraer interesantes conclusiones sobre las técnicas de elaboración, que son congruentes con la pervivencia de algunos procedimientos de ejecución de los enlucidos de raigambre romana. Además, se plantea aquí la existencia de un núcleo de producción que agruparía los ejemplos provenientes de Almería y Málaga, cuyo contexto técnico los diferenciaría.Alejandre Sánchez, FJ.; Núñez Guerrero, C.; Díaz Ramos, S.; Pérez-Malumbres Landa, A. (2023). Nuevas aportaciones a la diferenciación geográfica de los zócalos pintados andalusíes. Loggia, Arquitectura & Restauración. (36):40-51. https://doi.org/10.4995/loggia.2023.1996940513

Spiders from Macaronesia: Cabo Verde.

ABSTRACT: The data presented in this study were obtained from samples collected as part of the project "Macaronesian Islands as a testing ground to assess biodiversity drivers at multiple scales" (FCT - MACDIV) (2015-2018). This project aimed at gaining insights into the factors influencing community assembly in Macaronesian islands. To assess spider diversity, we employed the COBRA (Conservation Oriented Biodiversity Rapid Assessment) sampling protocol. Our sampling efforts were conducted in ten 50 m x 50 m dry shrub plots located on the Cabo Verde Islands of Santo Antão (comprising five plots) and São Vicente (comprising five plots). Additional ad-hoc samples are also available. With this publication, we contribute valuable information to the understanding of the arachnofauna of Cabo verde, specifically focusing on the islands of Santo Antão and São Vicente.info:eu-repo/semantics/publishedVersio

PLK1 regulates centrosome migration and spindle dynamics in male mouse meiosis

Cell division requires the regulation of karyokinesis and cytokinesis, which includes an essential role of the achromatic spindle. Although the functions of centrosomes are well characterised in somatic cells, their role during vertebrate spermatogenesis remains elusive. We have studied the dynamics of the meiotic centrosomes in male mouse during both meiotic divisions. Results show that meiotic centrosomes duplicate twice: first duplication occurs in the leptotene/zygotene transition, while the second occurs in interkinesis. The maturation of duplicated centrosomes during the early stages of prophase I and II are followed by their separation and migration to opposite poles to form bipolar spindles I and II. The study of the genetic mouse model Plk1(Δ/Δ) indicates a central role of Polo-like kinase 1 in pericentriolar matrix assembly, in centrosome maturation and migration, and in the formation of the bipolar spindles during spermatogenesis. In addition, in vitro inhibition of Polo-like kinase 1 and Aurora A in organotypic cultures of seminiferous tubules points out to a prominent role of both kinases in the regulation of the formation of meiotic bipolar spindlesThis work was supported by funding from Ministerio de Economía, Industria y Competitividad, Gobierno de España (MINECO) (Spain) [grant number BFU2014-53681-P and MEIONET (BFU2015-71786-REDT) to J. A. S. and grant number RTI2018-095582-B-I00 to M. M.]

A Gene Encoding Arginyl-tRNA Synthetase Is Located in the Upstream Region of the lysA Gene in Brevibacterium lactofermentum: Regulation of argS-lysA Cluster Expression by Arginine

International audienceThe Brevibacterium lactofermentum argS gene, which encodes an arginyl-tRNA synthetase, was identified in the upstream region of the lysA gene. The cloned gene was sequenced; it encodes a 550-amino-acid protein with an Mr of 59,797. The deduced amino acid sequence showed 28% identical and 49% similar residues when compared with the sequence of the Escherichia coli arginyl-tRNA synthetase. The B. lactofermentum enzyme showed the highly conserved motifs of class I aminoacyl-tRNA synthetases. Expression of the argS gene in B. lactofermentum and E. coli resulted in an increase in aminoacyl-tRNA synthetase activity, correlated with the presence in sodium dodecyl sulfate-polyacrylamide gels of a clear protein band that corresponds to this enzyme. One single transcript of about 3,000 nucleotides and corresponding to the B. lactofermentum argS-lysA operon was identified. The transcription of these genes is repressed by lysine and induced by arginine, showing an interesting pattern of biosynthetic interlock between the pathways of both amino acids in corynebacteria

Pumping Metallic Nanoparticles with Spatial Precision within Magnetic Mesoporous Platforms: 3D Characterization and Catalytic Application

The present work shows an efficient strategy to assemble two types of functional nanoparticles onto mesoporous MCM-41 silica nanospheres with a high degree of spatial precision. In a first stage, magnetite nanoparticles are synthesized with a size larger than the support pores and grafted covalently through a peptide-like bonding onto their external surface. This endowed the silica nanoparticles with a strong superparamagnetic response, while preserving the highly ordered interior space for the encapsulation of other functional guest species. Second, we report the finely controlled pumping of preformed Pt nanoparticles (1.5 nm) within the channels of the magnetic MCM-41 nanospheres to confer an additional catalytic functionality to the multiassembled nanoplatform. The penetration depth of the metallic nanoparticles can be explained as a result of the interplay between the particle-wall electrostatic attraction and the repulsive forces between neighboring Pt nanoparticles. A detailed transmission electron microscopy and a 3D high-resolution high-angle annular dark-field detector electron tomography study were carried out to characterize the material and to explain the assembly mechanism. Finally, the performance of these multifunctional nanohybrids as magnetically recoverable catalysts has been evaluated in the selective hydrogenation of p-nitrophenol, a well-known pollutant and intermediate in multiple industrial processes

Identification by Real-time PCR of 13 mature microRNAs differentially expressed in colorectal cancer and non-tumoral tissues

MicroRNAs (miRNAs) are short non-coding RNA molecules playing regulatory roles by repressing translation or cleaving RNA transcripts. Although the number of verified human miRNA is still expanding, only few have been functionally described. However, emerging evidences suggest the potential involvement of altered regulation of miRNA in pathogenesis of cancers and these genes are thought to function as both tumours suppressor and oncogenes. In our study, we examined by Real-Time PCR the expression of 156 mature miRNA in colorectal cancer. The analysis by several bioinformatics algorithms of colorectal tumours and adjacent non-neoplastic tissues from patients and colorectal cancer cell lines allowed identifying a group of 13 miRNA whose expression is significantly altered in this tumor. The most significantly deregulated miRNA being miR-31, miR-96, miR-133b, miR-135b, miR-145, and miR-183. In addition, the expression level of miR-31 was correlated with the stage of CRC tumor. Our results suggest that miRNA expression profile could have relevance to the biological and clinical behavior of colorectal neoplasia

Arthropod diversity in two Historic Gardens in the Azores, Portugal

The aim of our study was to characterise and compare the richness and composition of endemic, native (non-endemic) and introduced arthropod assemblages of two Azorean Historic Gardens with contrasting plant species composition. We hypothesised that Faial Botanic Garden would hold higher arthropod diversity and abundance of native and endemic arthropod species due to its larger native plant community. Species were collected using several arthropod standardised techniques between April 2017 and June 2018. We used the alpha diversity metrics (Hill series) and the partitioning of total beta diversity (βtotal) into its replacement (βrepl) and richness (βrich) components, to analyse the adult and total arthropod community. The orders Araneae, Coleoptera and Hemiptera were also studied separately. Our results show that the number of exotic arthropod species exceeds the number of native and/or the endemic species in both gardens, but the arthropod community of Faial Botanic Garden exhibited a higher density of endemic and native species. Despite some minor exceptions, the geographic origins of plant communities largely influenced the arthropod species sampled in each garden. This study improves our knowledge about urban arthropod diversity in the Azores and shows how well-designed urban garden management and planning contribute to the conservation of native and endemic Azorean species.European Commission; Azorean Public funds through Operational Program Azores 2020, under the project Green Garden Azores (ACORES-01-0145-FEDER-000070); Azorean Public funds through Operational Program Azores 2020, under the project AZORESBIOPORTAL (ACORES-01-0145-FEDER-000072).info:eu-repo/semantics/publishedVersio