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Cyclic peptides (CPs) formed by alternation of D- and L-amino acids (D,L-CPs) can self-assemble into nanotubes (SCPNs) by parallel or/and antiparallel stacking. Different applications have been attributed to these nanotubes, including the disruption of lipid bilayers of specific compositions and the selective transport of ions throughout membranes. Molecular dynamics (MD) simulations have significantly contributed to understand the interaction between CPs, including the structural, dynamic and transport properties of their supramolecular aggregates. The high computational cost of atomic resolution forcefields makes them impractical for simulating the self-assembly of macromolecules, so coarse-grained (CG) models might represent a more feasible solution for this purpose. However, general CG models used for the simulation of biomolecules such as the MARTINI forcefield do not explicitly consider the non-covalent interactions leading to the formation of secondary structure patterns in proteins. This becomes particularly important in the case of CPs due to the D- and L-chirality alternation in their sequence, leading to opposite orientations of the backbone polar groups on both sides of the cyclic ring plane. In order to overcome this limitation, we have extended the MARTINI forcefield to introduce chirality in each residue of the CPs. The new parametrization, which we have called MA(R/S)TINI, reproduces the expected self-assembly patterns for several CP sequences in the presence of different membrane models, explicitly considering the chirality of the CPs and with no significant extra computational cost. Our simulations provide new mechanistic information of how these systems self-assemble in presence of different lipid scenarios, showing that the CP-CP and CP-membrane interactions are sensitive to the peptide sequence chirality. This opens the door to design new bioactive CPs based on CG-MD simulations. A web-based tool for the automatic parameterization of new CP sequ

Ecological resistance and resilience of freshwater ecosystems is intimately linked to climate variability. To the extent of our knowledge, this issue has never been addressed using a long-term paleoecological perspective in Galicia (NW Spain). Project IMPACOM (Climate Impacts of the Common Era on Aquatic Systems in NW Spain, Spanish Ministry of Science and innovation, PID2019-107424RB-I00) is intended to study the impacts of changes in the precipitation regime and storm conditions, among other climate forcing factors, on coastal lakes and their enclosing barriers, as well as on bogs and mountain lakes in the region during the Common Era (CE, last 2,000 yr). To identify and precisely date the major ecological transitions of the CE we use a multidisciplinary approach which includes sedimentological facies analysis, inorganic bulk geochemical analyses (from X-ray fluorescence analysis, core scanning, Fourier-transform infrared spectroscopy, estimation of humification indexes, elemental and isotopic analyses of organic matter, biogenic silica), biological proxies (diatoms, pollen, plant macrofossils, testate amoeba and chironomids), as well as a set of geochronological techniques (AMS radiocarbon dating, concentrations of fallout 137Cs, 210Pb, 214Pb and 241Am, OSL dating), The study of the lacustrine sedimentary record of the coastal Lake Doniños, as well as of the sand barrier which encloses this lake and that of the wetland of Pantín, both in A Coruña province, shows a history of breaching and overwashing linked to the intensification of storms and enhanced precipitation over the last 4,500-4,000 yr. For the case of the last 2,000 yr, catastrophic emptying of Lake Doniños took place during the Dark Ages (DA, 350-750 CE) and the Little Ice Age (LIA, 1500-1930 CE). The transition from the Medieval Climate Anomaly (MCA) to the LIA involved in this lake a gradual 200 yr long transformation from an isolated lake to an intermittent tidal lagoon until the LIA breaching episode. Lake Ocelo, an oligotrophic mountain lake located in the Trevinca Massif (Ourense province) shows a net eutrophication trend since the termination of the Subatlantic period. This trend was however interrupted by oligotrophication events in the warm/cold transitions of the Roman Warm Period to the DA, lasting 500 years, and the MCA to LIA, which lasted 600 years. Extended ice cover during the LIA, as suggested by the preliminary diatom data, involved stronger denitrification processes associated to longer periods of anoxia, indicated by the nitrogen isotopic record. Anticipation of the oligotrophication events to the known chronologies for the onset of the DA and the LIA suggests that these two phases occurred approximately 100 and 200 years earlier than expected, according to other mountain lake record of the W Iberian Peninsula. Our preliminary data also show significant discrepancies in the timing of the ecological impacts of Recent Climate Changes (RCCs) taking place in the last 2,000 yr in coastal and mountain areas over a short longitudinal gradient which needs further exploration

A palladium catalytic system is reported for the divergent tandem cycloisomerization and cross-coupling of carbonyl- and imine-tethered alkylidenecyclopropanes (ACPs). The selection of ancillary ligands is pivotal for the interception of the heteropalladacyclic intermediates with different external nucleophiles

Despite the multidisciplinary and comprehensive approach taken in ref. 1, we acknowledge that there are still open questions that require further research. We emphasize that our study relies on multiple records that show the synchronous arrival of humans on multiple islands before ca. 1400 CE. Elias et al. (2) raise specific concerns about the record from Peixinho Lake, one of the five lakes included in the study, while ignoring the other multiproxy lake sediment records. The arguments presented by Elias et al. (2) do not undermine in any way the main conclusions of our paper, but still we would like to explicitly address the main criticisms with regard to the only record in question

[EN] The northwest region of the Iberian Peninsula is home to a unique ecosystem of bogs, which are particularly sensitive to projected climate change. In this context, the rate of carbon (C) accumulation in Chao de Veiga Mol, an intact raised bog, was analysed. Changes in the accumulation rate over the past 10 millennia were determined in a peat core of 847 cm in depth, with a high mean rate of peat growth (11 yr cm1, 0.09 cm yr1). An age-depth model was generated from 22 14C dates and fallout radionuclides. Chronological, stratigraphical and physico-chemical data confirmed the existence of a single cycle of peat formation throughout the Holocene and the formation of ombrotrophic peat 9500 years ago. The total mean C content was 50.2%, and over 10 millennia 583 kg C m2 accumulated at a mean rate of 35.3 g C m2 yr1, with a long-term (apparent) rate of carbon accumulation in the catotelm of 59.9 g C m2 yr1. These values are much higher than reported for other Iberian peatlands and are amongst the highest documented for peatlands in the northern hemisphere. The dynamics of C accumulation and other measured parameters reveals important variations throughout the Holocene. They could be associated with the main climatic events described in the northern hemisphere and are highly consistent with models established for northern latitudes. The Chao de Veiga Mol raised bog is unique and of great potential value for carrying out high resolution palaeoenvironmental studies, especially in relation to regional and local modulations in southern Europe

We report a versatile, highly enantioselective intramolecular hydrocarbonation reaction that provides a direct access to heteropolycyclic systems bearing chiral quaternary carbon stereocenters. The method, which relies on an iridium(I)/bisphosphine chiral catalyst, is particularly efficient for the synthesis of five-, six- and seven-membered fused indole and pyrrole products, bearing one and two stereocenters, with enantiomeric excesses of up to >99 %. DFT computational studies allowed to obtain a detailed mechanistic profile and identify a cluster of weak non-covalent interactions as key factors to control the enantioselectivity

Background: Testate amoebae are a polyphyletic group of protists living preferentially in soils, freshwaters and wetlands. These Protozoa have a worldwide distribution, but their presence and diversity in the Azores (a remote oceanic archipelago) is poorly known, with only twelve taxa recorded so far. The published information reflects occasional collections from sporadic field visits from naturalists to São Miguel Island, mainly in the nineteenth century. To overcome this limitation, a standardised survey was carried out on the Island, sampling different types of habitats from several localities to provide the distribution and information on species ecology of testate amoebae. New information: In this study, 43 species of testate amoebae were recorded (within a total of 499 occurrences), belonging to two orders of Protista (26 Arcellinida and 17 Euglyphida). The most frequently occurring testate amoebae were Euglypha strigosa, Trinema lineare, Euglypha rotunda, Assulina muscorum and Cyclopyxis eurystoma. The most diverse genus was Euglypha (six species). A total of 38 species are new records for the Azores Archipelago. These data help to improve knowledge of the geographical distribution of testate amoebae in the northern hemisphere and their diversity in the Azores Archipelago

Humans have made such dramatic and permanent changes to Earth's landscapes that much of it is now substantially and irreversibly altered from its preanthropogenic state. Remote islands, until recently isolated from humans, offer insights into how these landscapes evolved in response to human-induced perturbations. However, little is known about when and how remote systems were colonized because archaeological data and historical records are scarce and incomplete. Here, we use a multiproxy approach to reconstruct the initial colonization and subsequent environmental impacts on the Azores Archipelago. Our reconstructions provide unambiguous evidence for widespread human disturbance of this archipelago starting between 700-60+50 and 850-60+60 Common Era (CE), ca. 700 y earlier than historical records suggest the onset of Portuguese settlement of the islands. Settlement proceeded in three phases, during which human pressure on the terrestrial and aquatic ecosystems grew steadily (i.e., through livestock introductions, logging, and fire), resulting in irreversible changes. Our climate models suggest that the initial colonization at the end of the early Middle Ages (500 to 900 CE) occurred in conjunction with anomalous northeasterly winds and warmer Northern Hemisphere temperatures. These climate conditions likely inhibited exploration from southern Europe and facilitated human settlers from the northeast Atlantic. These results are consistent with recent archaeological and genetic data suggesting that the Norse were most likely the earliest settlers on the islands.

We describe the discovery of unprecedented annulation processes of 1,7-allenedienes, promoted by Pt or Au catalysts. These transformations revealed mechanistic pathways that had not been previously observed in reactions involving carbophilic catalysis. In particular, we have found that allenedienes bearing a silyl ether in the carbon tether connecting the diene and the allene divergently afford cyclopropane-embedded tricyclic derivatives, 6,6-fused bicarbocyclic products or 5,6-fused bicarbocyclic systems, depending on the type of Au or Pt catalyst used. We have carried out experimental and computational studies that shed light on the mechanistic reasons behind this rich and unusual skeletal divergence, and provide new lessons on the drastic influence of platinum ancillary ligands on the reaction outcome

The Natura 2000 network is an ambitious European project aimed at nature conservation. Nevertheless, the identification and delimitation of habitats is a complex task and simultaneously essential for correct ecosystem management. In this study we compared the current habitat delimitation and designation and the results produced by Geographic Information Systems (GIS) and geochemical proxies for the categorization of four coastal lakes in Galicia (NW Iberian Peninsula). The findings reveal important errors in the delimitation/designation. The first error is the designation of all four lakes as Coastal lagoons (habitat 1150), when geochemical data indicate that two of these lakes were always freshwater lakes and should consequently be classified as Natural eutrophic lakes (habitat 3150). Another error is of conceptual origin, because the lakes comprise a unique functional system composing of different environmental units (e.g., open water or aquatic vegetation). Subdivision into different habitats is therefore meaningless for units of negligible surface area. In addition, the designation of some habitats is very dubious according to the available data. Finally, notable changes in relation to the temporal changes of wetlands were observed. Thus, the area occupied by aquatic macrophytes increased greatly at the expense of open waters, and the increase was also reflected in the alluvial forest. This last finding indicates the importance of updating the state of Natura 2000 network in Galicia to improve habitat management

A high resolution core (9.7 yr cm 1 ) from the Chao de Veiga Mol raised bog (NW Iberian Peninsula) was analyzed to identify plant macrofossils, estimate peat humification and calculate hydroclimatic indices based on current bog species, with the overall aim of determining the climate conditions associated with evolution of the bog during the Medieval Climate Anomaly and the Little Ice Age. These proxies, together with historical and climate data, proved to be good indicators of the changes in bog surface wetness, Analysis: of the core led to identification of 9 different periods: two corresponding to the so-called Medieval Climate Anomaly (930 to 1345 AD, 1075–665 calibrated years before present [cal. yr BP]); four corresponding to the Little Ice Age (1345 to 1905 AD; 665–105 cal yr BP); and three corresponding to the last century (1905 to 2000 AD). The findings revealed a generally dry climate that lasted until the 14th century, followed by a transition to a long period with a more humid, but characteristically very variable climate, which ended at the beginning of the 20th century and was followed by a rapid transition to more humid conditions and finally, a change to drier conditions., The Medieval Climate Anomaly was indicated by the abundance of dry-adapted mosses (Leucobryum glaucum, Hypnum cupressiforme) and characterized by warm dry conditions and high levels of peat humification, with alternating wet phases. The LIA period was dated by a large abundance of Sphagnum species (an indicator of wetness) and a gradual increase in the humification index. However, four different climate phases were differentiated in this period., High-resolution reconstruction of the evolution of the CVM bog and the multiproxy approach have together enabled a more detailed identification of climatic variations in this area, which are generally consistent with the global models, as well as better definition of the elusive climatic oscillations in the last millennium and confirmation of the importance of local modulation of global models. The study provides new information and a detailed chronology of climatic events that will help to refine local modulation of the climate evolution model in the still quite unexplored region of the NW Iberian Peninsula, a key area for understanding the paleoclimatic dynamics in SW Europe.

The northwest region of the Iberian Peninsula is home to a unique ecosystem of bogs, which are particularly sensitive to projected climate change. In this context, the rate of carbon (C) accumulation in Chao de Veiga Mol, an intact raised bog, was analysed. Changes in the accumulation rate over the past 10 millennia were determined in a peat core of 847 cm in depth, with a high mean rate of peat growth (11 yr cm−1, 0.09 cm yr−1). An age-depth model was generated from 22 14C dates and fallout radionuclides. Chronological, stratigraphical and physico-chemical data confirmed the existence of a single cycle of peat formation throughout the Holocene and the formation of ombrotrophic peat 9500 years ago. The total mean C content was 50.2%, and over 10 millennia 583 kg C m−2 accumulated at a mean rate of 35.3 g C m−2 yr−1, with a long-term (apparent) rate of carbon accumulation in the catotelm of 59.9 g C m−2 yr−1. These values are much higher than reported for other Iberian peatlands and are amongst the highest documented for peatlands in the northern hemisphere. The dynamics of C accumulation and other measured parameters reveals important variations throughout the Holocene. They could be associated with the main climatic events described in the northern hemisphere and are highly consistent with models established for northern latitudes. The Chao de Veiga Mol raised bog is unique and of great potential value for carrying out high resolution palaeoenvironmental studies, especially in relation to regional and local modulations in southern Europe.

The analysis of plant macrofossils in peatland ecosystems has been widely used for the climatic and ecological reconstruction of the Holocene in the high latitudes of the northern hemisphere. By contrast, perhaps associated with rarity of these ecosystems, this proxy has barely been explored for southern Europe. In this work, a compilation and review of existing knowledge on the study of plant macrofossils of peatlands in southern Europe has been carried out, both from a paleoenvironmental perspective and in terms of biodiversity dynamics. Although small in surface area, the peatlands of southern Europe stand out for their diversity (botanical, edaphogenic, morphological, etc.), which has allowed the recovery of a large number of macrofossils from both vascular plants and bryophytes. The southern zone of Europe contains refuge zones with a high plant diversity that have not suffered the intense glaciation of the northern zones, this allows a continuous record since the beginning of the Holocene and the detection of climatic events in lower latitudes, where the ice recession was earlier.

Ecological resistance and resilience of freshwater coastal back-barrier perched lakes are intimately linked to the stability of the sand-barrier enclosing them, which controls the inflow of seawater. We address the long-term ecological changes (2,700 cal yr BP to present) in one of these systems in NW Spain (Doniños, A Coruña) from a multi-proxy paleoecological reconstruction based on biological, physical, and chemical analyses of its lacustrine sedimentary record, as well as on GPR surveys of the sand barrier. Although human intervention cannot be completely disregarded, AMS 14C and OSL datings show that ecological changes were synchronous with the main climatic periods of the studied interval. The ancient freshwater lake was catastrophically emptied due to barrier breaching coinciding with the increase of storms within the Dark Ages (350-750 CE) and the Little Ice Age (LIA, 1500-1930 CE), the latter characterized by an active retrograding sand barrier. Erosion induced by storms and increased rainfall generated two hiatuses which left no record of the ecological recovery of the system. By contrast, the transition from the Medieval Climate Anomaly to the LIA (1100-1500 CE) shows a gradual ecological transformation from an isolated lake towards a transitional shallow choked lagoon and, finally, an intermittent tidal lagoon, which lasted approx. 200 yr. Although determining whether an observed ecosystem change represents a regime shift in the framework of the Alternative Stable States Hypothesis is difficult in highly variable systems, this gradual change is here not ascribed as a sudden non-linear ecological regime shift. A 210Pb age-model for the upper sediments shows that the current freshwater lake was established c. 1945 CE, after the dune fields stabilized in the region associated to the known decrease in storm and wind intensities. Changes in the main North Atlantic atmospheric patterns in the last decades are considered the ultimate agents of the complete isol

This paper focuses on pollen, spores, non‐pollen palynomorphs (NPPs) and certain geochemical elements from the ombrotrophic blanket bog of Zalama (Basque‐Cantabrian Mountains, northern Iberian Peninsula), with the support of a robust chronology based on 17 AMS 14C dates. The main results related to the last 8000 years show that, during the early middle Holocene, pines and deciduous forests were the most extensive tree formations. At the beginning of the succession, pines reach 44%, showing regional presence, whereas after 7600 cal. a BP, deciduous forests were particularly abundant. From c. 6500 cal. a BP the pollen diagram constructed from our samples shows the first anthropogenic evidence, linked with the new economic practices related to the Neolithic of the Basque‐Cantabrian Mountains. From 3300 cal. a BP the expansion of Fagus sylvatica is particularly clear, and has since then become one of the dominant forest species in this region. We also discuss the Holocene evolution of other noteworthy plant communities in southwestern Europe, such as Taxus baccata, Juglans and shrublands.

We report an Ir(I)-catalyzed cycloisomerization methodology that provides access to carbocyclic systems bearing exo-alkene moieties from alkynyl-equipped acyclic precursors. The method relies on the C–H activation of olefinic and (hetero)aromatic C(sp2)–H bonds, followed by an exocyclization to a tethered alkyne, and provides interesting cyclic diene products that are amenable of further elaboration. Importantly, DFT calculations suggests that, in contrast to related hydrocarbonations of alkenes in which either migratory insertions or C–C reductive eliminations have been suggested to be rate-determining, in our reactions, the energetic barrier of these steps is lower than that of the previous C–H activation

Las turberas son ecosistemas con una distribución muy restringida en la Península Ibérica. Entre ellas las turberas ombrotróficas de cobertor constituyen un hábitat aún más escaso y en peligro grave de desaparición, a pesar de estar bajo la protección de diferentes normativas vigentes, tanto nacionales como internacionales. Además de su importancia ecológica, uno de sus mayores valores radica en su funcionamiento como archivos paleoambientales del pasado, principalmente del período Holoceno. La tesis está organizada en nueve capítulos; los tres primeros de carácter general, en el primero de los cuales se presenta una recopilación de información bibliográfica sobre turberas, haciendo hincapié en turberas de cobertor, sobre macrofósiles vegetales y sobre propiedades de la turba, particularmente el grado de humificación de la misma. El segundo capítulo contempla los objetivos de la tesis y el tercero la metodología utilizada. En el cuarto se presenta un estudio detallado de los distintos macrofósiles vegetales estudiados en tres turberas de cobertor y una elevada del norte de la Península Ibérica. De todos los taxones de macrofósiles identificados se realiza una descripción y se establecen las bases para su identificación, mediante claves dicotómicas con ilustraciones detalladas de los caracteres de mayor valor taxonómico. En los capítulos quinto y sexto se realizan las reconstrucciones paleoambientales durante el Holoceno, en la turbera vasca de Zalama en primer lugar y posteriormente en el caso de la turbera gallega de Borralleiras de Cal Grande; realizadas a partir de los macrofósiles vegetales extraídos de la turba y de los resultados de los análisis de la turba, especialmente los del grado de humificación, el contenido en elementos litogénicos, carbones y la tasa de crecimiento vertical. La comparación de diferentes registros bióticos y abióticos ha permitido reconstruir la dinámica de las condiciones hidrológicas, es decir, de la humedad superficial de la turbera

New record of a population of Cyperus papyrus L. naturalized in Galicia, NW of Spain, extends the biogeographic range of distribution of this non-indigenous species in the Iberian Peninsula., Nueva cita de una población de Cyperus papyrus L. naturalizada en Galicia, NO de España, amplía el rango biogeográfico de distribución de esta especie alóctona en la Península Ibérica.

In the present study we reviewed the genesis, development and classification of peatlands in the Iberian Peninsula by conducting chronostratigraphic analysis of 108 of these ecosystems. The findings are summarised as follows: 1. The region has a wide variety of peatlands which are classified according to their biogeochemical, geomorphological and ecological characteristics into different types of bogs and fens. 2. Most of the peatlands occur in the Atlantic region followed by the Mediterranean and Alpine regions. Fens are more widely distributed than bogs, and blanket and raised bogs are mainly found in the Eurosiberian biogeographical region. 3. In many of the fens, the last active peat-forming cycle occurred during the Late Holocene (43 %). In most of the bogs, the peat-forming cycle occurred in the Middle Holocene (70 %), although in a substantial proportion of blanket bogs these processes occurred in the Early Holocene (30 %). 4. The peat formed in the last active cycle is, on average, thicker in raised bogs (322 cm) than in blanket bogs (257 cm) and fens (156 cm). 5. Vertical peat accumulation rates varied between 16 and 30 yr cm-1 in more than 40 % of the peatlands. The accumulation rates differed significantly between the different types of peatlands and were highest in the raised bogs. The accumulation rates were very variable in the fens. 6. The genesis, evolution and types of Iberian peatlands are similar to those observed in peatlands in northern latitudes in Europe and North America

En la turbera ombrotrófica de Zalama (País Vasco) se han estudiado los macrorrestos vegetales y se ha realizado un análisis de la humificación de la turba, para establecer una reconstrucción paleoambiental de las condiciones de hidrológicas de la turbera en los últimos 8000 años. Ambos proxies, que muestran una apreciable concordancia, permitieron diferenciar 4 períodos de elevada humedad superficial (8000-7400, 6400-5640, 1050-480 y 480-300 BP) entre los que se intercalan otros más secos con zonas de transición seco-húmedo.

Museo de arte y arqueología en el Valle del Côa

Raposeiro, P. M., Hernández, A., Pla-Rabes, S., Gonçalves, V., Bao, R., Sáez, A., . . . Giralt, S. (2021). Climate change facilitated the early colonization of the Azores Archipelago during medieval times. In Proceedings of the National Academy of Sciences (article e2108236118). US National Academy of Sciences. https://doi.org/10.1073/pnas.2108236118

Raposeiro, P. M., Hernández, A., Pla-Rabes, S., Gonçalves, V., Bao, R., Sáez, A., . . . Giralt, S. (2022). Reply to Elias et al.: Multiproxy evidence of widespread landscape disturbance in multiple Azorean lakes before the Portuguese arrival. Proceedings of the National Academy of Sciences, 119(4), article e2120107119. https://doi.org/10.1073/pnas.2120107119