Thermal tolerance does not explain the altitudinal segregation of lowland and alpine aquatic insects

Elevation gradients provide powerful study systems for examining the influence of environmental filters in shaping species assemblages. High-mountain habitats host specific high-elevation assemblages, often comprising specialist species adapted to endure pronounced abiotic stress, while such harsh conditions prevent lowland species from colonizing or establishing. While thermal tolerance may drive the altitudinal segregation of ectotherms, its role in structuring aquatic insect communities remains poorly explored. This study investigates the role of thermal physiology in shaping the current distribution of high-mountain diving beetles from the Sierra Nevada Iberian mountain range and closely related lowland species. Cold tolerance of five species from each altitudinal zone was measured estimating the supercooling point (SCP), lower lethal temperature (LLT) and tolerance to ice enclosure, while heat tolerance was assessed from the heat coma temperature (HCT). Alpine species exhibited wider fundamental thermal niches than lowland species, likely associated with the broader range of climatic conditions in high-mountain areas. Cold tolerance did not seem to prevent lowland species from colonizing higher elevations, as most studied species were moderately freeze-tolerant. Therefore, fundamental thermal niches seem not to fully explain species segregation along elevation gradients, suggesting that other thermal tolerance traits, environmental factors, and biotic interactions may also play important roles.

Novel Microsatellite Loci, Cross-Species Validation of Multiplex Assays, and By-Catch Mitochondrial Genomes on Ochthebius Beetles from Supratidal Rockpools

Here we focus on designing, for the first time, microsatellite markers for evolutionary and ecological research on aquatic beetles from the genus Ochthebius (Coleoptera, Hydraenidae). Some of these non-model species, with high cryptic diversity, exclusively inhabit supratidal rockpools, extreme and highly dynamic habitats with important anthropogenic threats. We analysed 15 individuals of four species (O. lejolisii, O. subinteger, O. celatus, and O. quadricollis) across 10 localities from the Mediterranean coasts of Spain and Malta. Using next-generation sequencing technology, two libraries were constructed to interpret the species of the two subgenera present consistently (Ochthebius s. str., O. quadricollis; and Cobalius, the rest of the species). Finally, 20 markers (10 for each subgenus) were obtained and successfully tested by cross-validation in the four species under study. As a by-catch, we could retrieve the complete mitochondrial genomes of O. lejolisii, O. quadricollis, and O. subinteger. Interestingly, the mitochondrial genome of O. quadricollis exhibited high genetic variability compared to already published data. The novel SSR panels and mitochondrial genomes for Ochthebius will be valuable in future research on species identification, diversity, genetic structure, and population connectivity in highly dynamic and threatened habitats such as supratidal coastal rockpools.

The recovery of European freshwater biodiversity has come to a halt

Owing to a long history of anthropogenic pressures, freshwater ecosystems are among the most vulnerable to biodiversity loss1. Mitigation measures, including wastewater treatment and hydromorphological restoration, have aimed to improve environmental quality and foster the recovery of freshwater biodiversity2. Here, using 1,816 time series of freshwater invertebrate communities collected across 22 European countries between 1968 and 2020, we quantified temporal trends in taxonomic and functional diversity and their responses to environmental pressures and gradients. We observed overall increases in taxon richness (0.73% per year), functional richness (2.4% per year) and abundance (1.17% per year). However, these increases primarily occurred before the 2010s, and have since plateaued. Freshwater communities downstream of dams, urban areas and cropland were less likely to experience recovery. Communities at sites with faster rates of warming had fewer gains in taxon richness, functional richness and abundance. Although biodiversity gains in the 1990s and 2000s probably reflect the effectiveness of water-quality improvements and restoration projects, the decelerating trajectory in the 2010s suggests that the current measures offer diminishing returns. Given new and persistent pressures on freshwater ecosystems, including emerging pollutants, climate change and the spread of invasive species, we call for additional mitigation to revive the recovery of freshwater biodiversity.

Genomic data support multiple introductions and explosive demographic expansions in a highly invasive aquatic insect

The study of the genetic makeup and demographic fate of alien species is essential to understand their capacity to recover from founder effects, adapt to new environmental conditions and, ultimately, become invasive and potentially damaging. Here, we employ genomic data to gain insights into key demographic processes that might help to explain the extraordinarily successful invasion of the Western Mediterranean region by the North American boatman Trichocorixa verticalis (Hemiptera: Corixidae). Our analyses revealed the genetic distinctiveness of populations from the main areas comprising the invasive range and coalescent-based simulations supported that they originated from independent introductions events probably involving different source populations. Testing of alternative demographic models indicated that all populations experienced a strong bottleneck followed by a recent and instantaneous demographic expansion that restored a large portion (>30%) of their ancestral effective population sizes shortly after introductions took place (<60 years ago). Considerable genetic admixture of some populations suggest that hypothetical barriers to dispersal (i.e., land and sea water) are permeable to gene flow and/or that they originated from introductions involving multiple lineages. This study demonstrates the repeated arrival of propagules with different origins and short time lags between arrival and establishment, emphasizing the extraordinary capacity of the species to recover from founder effects and genetically admix in invaded areas. This can explain the demonstrated capacity of this aquatic insect to spread and outcompete native species once it colonizes new suitable regions. Future genomic analyses of native range populations could help to infer the genetic makeup of introduced populations and track invasion routes.

A setup to measure the temperature-dependent heating power of magnetically heated nanoparticles up to high temperature

Magnetic heating, namely, the use of heat released by magnetic nanoparticles (MNPs) excited with a high-frequency magnetic field, has so far been mainly used for biological applications. More recently, it has been shown that this heat can be used to catalyze chemical reactions, some of them occurring at temperatures up to 700 °C. The full exploitation of MNP heating properties requires the knowledge of the temperature dependence of their heating power up to high temperatures. Here, a setup to perform such measurements is described based on the use of a pyrometer for high-temperature measurements and on a protocol based on the acquisition of cooling curves, which allows us to take into account calorimeter losses. We demonstrate that the setup permits to perform measurements under a controlled atmosphere on solid state samples up to 550 °C. It should in principle be able to perform measurements up to 900 °C. The method, uncertainties, and possible artifacts are described and analyzed in detail. The influence on losses of putting under vacuum different parts of the calorimeter is measured. To illustrate the setup possibilities, the temperature dependence of heating power is measured on four samples displaying very different behaviors. Their heating power increases or decreases with temperature, displaying temperature sensibilities ranging from -2.5 to +4.4% K^-1. This setup is useful to characterize the MNPs for magnetically heated catalysis applications and to produce data that will be used to test models permitting to predict the temperature dependence of MNP heating power.

DISPERSE, a trait database to assess the dispersal potential of European aquatic macroinvertebrates

Dispersal is an essential process in population and community dynamics, but is difficult to measure in the field. In freshwater ecosystems, information on biological traits related to organisms' morphology, life history and behaviour provides useful dispersal proxies, but information remains scattered or unpublished for many taxa. We compiled information on multiple dispersal-related biological traits of European aquatic macroinvertebrates in a unique resource, the DISPERSE database. DISPERSE includes nine dispersal-related traits subdivided into 39 trait categories for 480 taxa, including Annelida, Mollusca, Platyhelminthes, and Arthropoda such as Crustacea and Insecta, generally at the genus level. Information within DISPERSE can be used to address fundamental research questions in metapopulation ecology, metacommunity ecology, macroecology and evolutionary ecology. Information on dispersal proxies can be applied to improve predictions of ecological responses to global change, and to inform improvements to biomonitoring, conservation and management strategies. The diverse sources used in DISPERSE complement existing trait databases by providing new information on dispersal traits, most of which would not otherwise be accessible to the scientific community.

Role of cuticle hydrocarbons composition in the salinity tolerance of aquatic beetles

Salinity tolerance has enabled the colonization of inland saline waters and promoted species diversification in some lineages of aquatic insects. However, the mechanisms behind this tolerance, particularly the role of cuticle hydrocarbons (CHCs), are not well-known. We characterized the CHC profile of eight species of two water beetle genera (Nebrioporus, Adephaga: Dytiscidae and Enochrus, Polyphaga: Hydrophilidae), which span the fresh-hypersaline gradient, to: i) determine the interspecific variation of CHC composition in relation to species' salinity tolerance; ii) explore plastic adjustments in CHC profiles in response to salinity changes at the intraspecific level in saline-tolerant species. CHC profiles were highly species-specific, more complex and diverse in composition, and characterized by longer-chain-length compounds in the species with higher salinity tolerance within each genus. Higher salinity tolerance in the Enochrus species was also associated with an increase in the relative abundance of branched alkanes, and with a lower proportion of n-alkanes and unsaturated compounds. These CHC characteristics are related with improved waterproofing capacity and suggest that reducing cuticle permeability was one of the key mechanisms to adapt to saline waters. Similar CHC composition patterns were found at the intraspecific level between populations from lower and higher salinity sites within saline-tolerant species of each genus. These saline species also displayed an extraordinary ability to adjust CHC profiles to changing salinity conditions in the laboratory in a relatively short time, which reflects great plasticity and a high potential to deal with daily and seasonal environmental fluctuations in the highly dynamic saline habitats.

Effect of Spin Clustering on Basic and Relaxometric Properties of Magnetic Nanoparticles

An increasing awareness about novel medical applications of smaller, inorganic-based nanoparticles, possessing unique properties at the nanoscale, has led to a burst of research activities in the development of "nanoprobes" for diagnostic medicine and agents for novel, externally activated therapies. In this research field magnetic nanoparticles are prominent due to fundamental peculiar properties particularly appealing for their use in materials and biomedical applications. Aiming to study the relationship between the topology of the magnetic nanoparticles and their efficacy as MRI contrast agents (relaxometric properties), we prepared three different stable colloidal suspension (ferrofluid) of magnetic nanobeads (MNBs) constituted by a discrete number of maghemite nanoparticles, arranged in disordered clusters or ordered in a polymeric matrix. An accurate morpho-dimensional and magnetic characterization displays the close correlation between the magnetic fundamental properties and the topology of our spin systems. The NMR relaxometry profiles confirmed the nature of the physical mechanisms inducing the increase of nuclear relaxation rates at low (magnetic anisotropy) and high (Curie relaxation) magnetic fields. Moreover the transverse relaxivity (r₂) values for all the MNBs are higher than those of common contrast agents and the differences between the three MNBs are suggested to be due to the spin topology effect.

Evaluating anthropogenic impacts on naturally stressed ecosystems: Revisiting river classifications and biomonitoring metrics along salinity gradients

Naturally stressed ecosystems hold a unique fraction of biodiversity. However, they have been largely ignored in biomonitoring and conservation programmes, such as the EU Water Framework Directive, while global change pressures are threatening their singular values. Here we present a framework to classify and evaluate the ecological quality of naturally stressed rivers along a water salinity gradient. We gathered datasets, including aquatic macroinvertebrate assemblages and environmental information, for 243 river locations across the western Mediterranean to: a) gauge the role of natural stressors (salinity) in driving aquatic community richness and composition; b) make river classifications by encompassing the wide range of environmental and biological variation exhibited by Mediterranean rivers; c) provide effective biomonitoring metrics of ecological quality for saline rivers. Our results showed that water salinity played a pivotal role in explaining the community richness and compositional changes in rivers, even when considering other key and commonly used descriptors, such as elevation, climate or lithology. Both environmental and biologically-based classifications included seven river types: three types of freshwater perennial rivers, one freshwater intermittent river type and three new saline river types. These new saline types were not included in previous classifications. Their validation by independent datasets showed that the saline and freshwater river types represented differentiable macroinvertebrate assemblages at family and species levels. Biomonitoring metrics based on the abundance of indicator taxa of each saline river type provided a much better assessment of the ecological quality of saline rivers than other widely used biological metrics and indices. Here we demonstrate that considering natural stressors, such as water salinity, is essential to design effective and accurate biomonitoring programmes for rivers and to preserve their unique biodiversity.

Insect communities in saline waters consist of realized but not fundamental niche specialists

Considering how organisms adapt to stress is essential if we are to anticipate biological responses to global change in ecosystems. Communities in stressful environments can potentially be assembled by specialists (i.e. species that only occur in a limited range of environmental conditions) and/or generalist species with wider environmental tolerances. We review the existing literature on the salinity tolerance of aquatic insects previously identified as saline specialists because they were exclusively found in saline habitats, and explore if these saline realized niche specialists are also specialists in their fundamental niches or on the contrary are fundamental niche generalist species confined to the highest salinities they can tolerate. The results suggest that species inhabiting saline waters are generalists in their fundamental niches, with a predominant pattern of high survival in freshwater-low salinity conditions, where their fitness tends to be similar or even higher than in saline waters. Additionally, their performance in freshwater tends to be similar to related strictly freshwater species, so no apparent trade-off of generalization is shown. These results are discussed in the framework of the ecological and evolutionary processes driving community assembly across the osmotic stress gradient, and their potential implications for predicting impacts from saline dilution and freshwater salinization.This article is part of the theme issue 'Salt in freshwaters: causes, ecological consequences and future prospects'.

Do all roads lead to Rome? Exploring community trajectories in response to anthropogenic salinization and dilution of rivers

Abiotic stress shapes how communities assemble and support ecological functions. However, it remains unclear whether artificially increasing or decreasing stress levels would lead to communities assembling predictably along a single axis of variation or along multiple context-dependent trajectories of change. In response to stress intensity alterations, we hypothesize that a single trajectory of change occurs when trait-based assembly prevails, while multiple trajectories of change arise when dispersal-related processes modify colonization and trait-filtering dynamics. Here, we tested these hypotheses using aquatic macroinvertebrates from rivers exposed to gradients of natural salinity and artificially diluted or salinized ion contents. Our results showed that trait-filtering was important in driving community assembly in natural and diluted rivers, while dispersal-related processes seemed to play a relevant role in response to salinization. Salinized rivers showed novel communities with different trait composition, while natural and diluted communities exhibited similar taxonomic and trait compositional patterns along the conductivity gradient. Our findings suggest that the artificial modification of chemical stressors can result in different biological communities, depending on the direction of the change (salinization or dilution), with trait-filtering, and organism dispersal and colonization dynamics having differential roles in community assembly. The approach presented here provides both empirical and conceptual insights that can help in anticipating the ecological effects of global change, especially for those stressors with both natural and anthropogenic origins.This article is part of the theme issue 'Salt in freshwaters: causes, ecological consequences and future prospects'.

Effects of salinity changes on aquatic organisms in a multiple stressor context

Under global change, the ion concentration of aquatic ecosystems is changing worldwide. Many freshwater ecosystems are being salinized by anthropogenic salt inputs, whereas many naturally saline ones are being diluted by agricultural drainages. This occurs concomitantly with changes in other stressors, which can result in additive, antagonistic or synergistic effects on organisms. We reviewed experimental studies that manipulated salinity and other abiotic stressors, on inland and transitional aquatic habitats, to (i) synthesize their main effects on organisms' performance, (ii) quantify the frequency of joint effect types across studies and (iii) determine the overall individual and joint effects and their variation among salinity-stressor pairs and organism groups using meta-analyses. Additive effects were slightly more frequent (54%) than non-additive ones (46%) across all the studies (n = 105 responses). However, antagonistic effects were dominant for the stressor pair salinity and toxicants (44%, n = 43), transitional habitats (48%, n = 31) and vertebrates (71%, n = 21). Meta-analyses showed detrimental additive joint effects of salinity and other stressors on organism performance and a greater individual impact of salinity than the other stressors. These results were consistent across stressor pairs and organism types. These findings suggest that strategies to mitigate multiple stressor impacts on aquatic ecosystems should prioritize restoring natural salinity concentrations.This article is part of the theme issue 'Salt in freshwaters: causes, ecological consequences and future prospects'.

Highly dense linkage maps from 31 full-sibling families of turbot (Scophthalmus maximus) provide insights into recombination patterns and chromosome rearrangements throughout a newly refined genome assembly

Highly dense linkage maps enable positioning thousands of landmarks useful for anchoring the whole genome and for analysing genome properties. Turbot is the most important cultured flatfish worldwide and breeding programs in the fifth generation of selection are targeted to improve growth rate, obtain disease resistant broodstock and understand sex determination to control sex ratio. Using a Restriction-site Associated DNA approach, we genotyped 18,214 single nucleotide polymorphism in 1,268 turbot individuals from 31 full-sibling families. Individual linkage maps were combined to obtain a male, female and species consensus maps. The turbot consensus map contained 11,845 markers distributed across 22 linkage groups representing a total normalised length of 3,753.9 cM. The turbot genome was anchored to this map, and scaffolds representing 96% of the assembly were ordered and oriented to obtain the expected 22 megascaffolds according to its karyotype. Recombination rate was lower in males, especially around centromeres, and pairwise comparison of 44 individual maps suggested chromosome polymorphism at specific genomic regions. Genome comparison across flatfish provided new evidence on karyotype reorganisations occurring across the evolution of this fish group.

Physiological niche and geographical range in European diving beetles (Coleoptera: Dytiscidae)

Geographical ranges vary greatly in size and position, even within recent clades, but the factors driving this remain poorly understood. In aquatic beetles, thermal niche has been shown to be related to both the relative range size and position of congeners but whether other physiological parameters play a role is unknown. Metabolic plasticity may be critical for species occupying more variable thermal environments and maintaining this plasticity may trade-off against other physiological processes such as immunocompetence. Here we combine data on thermal physiology with measures of metabolic plasticity and immunocompetence to explore these relationships in Deronectes (Dytiscidae). While variation in latitudinal range extent and position was explained in part by thermal physiology, aspects of metabolic plasticity and immunocompetence also appeared important. Northerly distributed, wide-ranging species apparently used different energy reserves under thermal stress from southern endemic congeners and differed in their antibacterial defences. This is the first indication that these processes may be related to geographical range, and suggests parameters that may be worthy of exploration in other taxa.

The chicken or the egg? Adaptation to desiccation and salinity tolerance in a lineage of water beetles

Transitions from fresh to saline habitats are restricted to a handful of insect lineages, as the colonization of saline waters requires specialized mechanisms to deal with osmotic stress. Previous studies have suggested that tolerance to salinity and desiccation could be mechanistically and evolutionarily linked, but the temporal sequence of these adaptations is not well established for individual lineages. We combined molecular, physiological and ecological data to explore the evolution of desiccation resistance, hyporegulation ability (i.e., the ability to osmoregulate in hyperosmotic media) and habitat transitions in the water beetle genus Enochrus subgenus Lumetus (Hydrophilidae). We tested whether enhanced desiccation resistance evolved before increases in hyporegulation ability or vice versa, or whether the two mechanisms evolved in parallel. The most recent ancestor of Lumetus was inferred to have high desiccation resistance and moderate hyporegulation ability. There were repeated shifts between habitats with differing levels of salinity in the radiation of the group, those to the most saline habitats generally occurring more rapidly than those to less saline ones. Significant and accelerated changes in hyporegulation ability evolved in parallel with smaller and more progressive increases in desiccation resistance across the phylogeny, associated with the colonization of meso- and hypersaline waters during global aridification events. All species with high hyporegulation ability were also desiccation-resistant, but not vice versa. Overall, results are consistent with the hypothesis that desiccation resistance mechanisms evolved first and provided the physiological basis for the development of hyporegulation ability, allowing these insects to colonize and diversify across meso- and hypersaline habitats.

Cuticle hydrocarbons in saline aquatic beetles

Hydrocarbons are the principal component of insect cuticle and play an important role in maintaining water balance. Cuticular impermeability could be an adaptative response to salinity and desiccation in aquatic insects; however, cuticular hydrocarbons have been poorly explored in this group and there are no previous data on saline species. We characterized cuticular hydrocarbons of adults and larvae of two saline aquatic beetles, namely Nebrioporus baeticus (Dytiscidae) and Enochrus jesusarribasi (Hydrophilidae), using a gas chromatograph coupled to a mass spectrometer. The CHC profile of adults of both species, characterized by a high abundance of branched alkanes and low of unsaturated alkenes, seems to be more similar to that of some terrestrial beetles (e.g., desert Tenebrionidae) compared with other aquatic Coleoptera (freshwater Dytiscidae). Adults of E. jesusarribasi had longer chain compounds than N. baeticus, in agreement with their higher resistance to salinity and desiccation. The more permeable cuticle of larvae was characterized by a lower diversity in compounds, shorter carbon chain length and a higher proportion of unsaturated hydrocarbons compared with that of the adults. These results suggest that osmotic stress on aquatic insects could exert a selection pressure on CHC profile similar to aridity in terrestrial species.

Metabolic and reproductive plasticity of core and marginal populations of the eurythermic saline water bug Sigara selecta (Hemiptera: Corixidae) in a climate change context

Ongoing climate change is driving dramatic range shifts in diverse taxa worldwide, and species responses to global change are likely to be determined largely by population responses at geographical range margins. Here we investigate the metabolic and reproductive plasticity in response to water temperature and salinity variation of two populations of the eurythermic saline water bug Sigara selecta: one population located close to the northern edge of its distribution, in a relatively cold, thermally stable region (SE England - 'marginal'), and one close to the range centre, in a warmer and more thermally variable Mediterranean climate (SE Spain - 'core'). We compared metabolic and oviposition rates and egg size, following exposure to one of four different combinations of temperature (15 and 25°C) and salinity (10 and 35gL^-1). Oviposition rate was significantly higher in the marginal population, although eggs laid were smaller overall. No significant differences in oxygen consumption rates were found between core and marginal populations, although the marginal population showed higher levels of plasticity in both metabolic and reproductive traits. Our results suggest that population-specific responses to environmental change are complex and may be mediated by differences in phenotypic plasticity. In S. selecta, the higher plasticity of the marginal population may facilitate both its persistence in current habitats and northward expansion with future climatic warming. The less plastic core population may be able to buffer current environmental variability with minor changes in metabolism and fecundity, but could be prone to extinction if temperature and salinity changes exceed physiological tolerance limits in the future.

Aquatic insects in a multistress environment: cross-tolerance to salinity and desiccation

Exposing organims to a particular stressor may enhance tolerance to a subsequent stress, when protective mechanisms against both stressors are shared. Such cross-tolerance is a common adaptive response in dynamic multivariate environments and often indicates potential co-evolution of stress traits. Many aquatic insects in inland saline waters from Mediterranean-climate regions are sequentially challenged with salinity and desiccation stress. Thus, cross-tolerance to these physiologically similar stressors could have been positively selected in insects of these regions. We used adults of the saline water beetles Enochrus jesusarribasi (Hydrophilidae) and Nebrioporus baeticus (Dytiscidae) to test cross-tolerance responses to desiccation and salinity. In independent laboratory experiments, we evaluated the effects of i) salinity stress on the subsequent resistance to desiccation and ii) desiccation stress (rapid and slow dehydration) on the subsequent tolerance to salinity. Survival, water loss and haemolymph osmolality were measured. Exposure to stressful salinity improved water control under subsequent desiccation stress in both species, with a clear cross-tolerance (enhanced performance) in N. baeticus. In contrast, general negative effects on performance were found under the inverse stress sequence. The rapid and slow dehydration produced different water loss and haemolymph osmolality dynamics that were reflected in different survival patterns. Our finding of cross-tolerance to salinity and desiccation in ecologically similar species from distant lineages, together with parallel responses between salinity and thermal stress previously found in several aquatic taxa, highlights the central role of adaption to salinity and co-occurring stressors in arid inland waters, having important implications for the species' persistence under climate change.

A new species of Aphelocheirus (Hemiptera: Heteroptera: Aphelocheiridae) from Morocco

This paper provides the description of a new species of Aphelocheirus (Hemiptera: Heteroptera: Aphelocheiridae), Aphelocheirus pemae sp. nov. from Morocco. The species was found in two sites located in different basins (Sebou and Moulouya rivers) that are separated by approximately 400 km. Photographs of the dorsal habitus of the female and illustrations of the male genitalic structures are provided. A graphical key to species of the genus in Western Europe and the Maghreb is also included. The new species can be easily distinguished by the unique shape of the left and right parameres and absence of apical spines on the aedeagus.

The use of calcite mineral thermoluminescence for the determination of previously received gamma radiation dose in foodstuffs/E1 uso de la termoluminiscencia de la calcita para la determinación de la dosis de radiación gamma de alimentos previamente irradiados

This paper describes the potential use of calcite mineral dust as a high-dose radiation dosemeter. The results obtained show that saturation dose in natural calcite is of the order of 7 kGy. Measurements of absorbed dose, for samples previously irradiated with known gamma doses, showed a good level of agreement between actual doses and calculated doses, although the level of scatter is high.

Aquatic insects dealing with dehydration: do desiccation resistance traits differ in species with contrasting habitat preferences?

Background

Desiccation resistance shapes the distribution of terrestrial insects at multiple spatial scales. However, responses to drying stress have been poorly studied in aquatic groups, despite their potential role in constraining their distribution and diversification, particularly in arid and semi-arid regions.

Methods

We examined desiccation resistance in adults of four congeneric water beetle species (Enochrus, family Hydrophilidae) with contrasting habitat specificity (lentic vs. lotic systems and different salinity optima from fresh- to hypersaline waters). We measured survival, recovery capacity and key traits related to desiccation resistance (fresh mass, % water content, % cuticle content and water loss rate) under controlled exposure to desiccation, and explored their variability within and between species.

Results

Meso- and hypersaline species were more resistant to desiccation than freshwater and hyposaline ones, showing significantly lower water loss rates and higher water content. No clear patterns in desiccation resistance traits were observed between lotic and lentic species. Intraspecifically, water loss rate was positively related to specimens’ initial % water content, but not to fresh mass or % cuticle content, suggesting that the dynamic mechanism controlling water loss is mainly regulated by the amount of body water available.

Discussion

Our results support previous hypotheses suggesting that the evolution of desiccation resistance is associated with the colonization of saline habitats by aquatic beetles. The interespecific patterns observed in Enochrus also suggest that freshwater species may be more vulnerable than saline ones to drought intensification expected under climate change in semi-arid regions such as the Mediterranean Basin.

Freshwater ecosystems and aquatic insects: a paradox in biological invasions

Biological invasions have increased significantly in response to global change and constitute one of the major causes of biodiversity loss. Insects make up a large fraction of invasive species, in general, and freshwaters are among the most invaded ecosystems on our planet. However, even though aquatic insects dominate most inland waters, have unparalleled taxonomic diversity and occupy nearly all trophic niches, there are almost no invasive insects in freshwaters. We present some hypotheses regarding why aquatic insects are not common among aquatic invasive organisms, suggesting that it may be the result of a suite of biological, ecological and anthropogenic factors. Such specific knowledge introduces a paradox in the current scientific discussion on invasive species; therefore, a more in-depth understanding could be an invaluable aid to disentangling how and why biological invasions occur.

Atlas of Iberian water beetles (ESACIB database)

The ESACIB ('EScarabajos ACuáticos IBéricos') database is provided, including all available distributional data of Iberian and Balearic water beetles from the literature up to 2013, as well as from museum and private collections, PhD theses, and other unpublished sources. The database contains 62,015 records with associated geographic data (10×10 km UTM squares) for 488 species and subspecies of water beetles, 120 of them endemic to the Iberian Peninsula and eight to the Balearic Islands. This database was used for the elaboration of the "Atlas de los Coleópteros Acuáticos de España Peninsular". In this dataset data of 15 additional species has been added: 11 that occur in the Balearic Islands or mainland Portugal but not in peninsular Spain and an other four with mainly terrestrial habits within the genus Helophorus (for taxonomic coherence). The complete dataset is provided in Darwin Core Archive format.

The comparative osmoregulatory ability of two water beetle genera whose species span the fresh-hypersaline gradient in inland waters (Coleoptera: Dytiscidae, Hydrophilidae)

A better knowledge of the physiological basis of salinity tolerance is essential to understanding the ecology and evolutionary history of organisms that have colonized inland saline waters. Coleoptera are amongst the most diverse macroinvertebrates in inland waters, including saline habitats; however, the osmoregulatory strategies they employ to deal with osmotic stress remain unexplored. Survival and haemolymph osmotic concentration at different salinities were examined in adults of eight aquatic beetle species which inhabit different parts of the fresh-hypersaline gradient. Studied species belong to two unrelated genera which have invaded saline waters independently from freshwater ancestors; Nebrioporus (Dytiscidae) and Enochrus (Hydrophilidae). Their osmoregulatory strategy (osmoconformity or osmoregulation) was identified and osmotic capacity (the osmotic gradient between the animal's haemolymph and the external medium) was compared between species pairs co-habiting similar salinities in nature. We show that osmoregulatory capacity, rather than osmoconformity, has evolved independently in these different lineages. All species hyperegulated their haemolymph osmotic concentration in diluted waters; those living in fresh or low-salinity waters were unable to hyporegulate and survive in hyperosmotic media (> 340 mosmol kg(-1)). In contrast, the species which inhabit the hypo-hypersaline habitats were effective hyporegulators, maintaining their haemolymph osmolality within narrow limits (ca. 300 mosmol kg(-1)) across a wide range of external concentrations. The hypersaline species N. ceresyi and E. jesusarribasi tolerated conductivities up to 140 and 180 mS cm(-1), respectively, and maintained osmotic gradients over 3500 mosmol kg(-1), comparable to those of the most effective insect osmoregulators known to date. Syntopic species of both genera showed similar osmotic capacities and in general, osmotic responses correlated well with upper salinity levels occupied by individual species in nature. Therefore, osmoregulatory capacity may mediate habitat segregation amongst congeners across the salinity gradient.

Hematotoxicity of magnetite nanoparticles coated with polyethylene glycol: in vitro and in vivo studies

Hematotoxicity of magnetite nanoparticles with different coatings has been evaluated by determining their safety in vitro and in vivo in a rat model up to 30 days.

Observation of zero-point quantum fluctuations of a single-molecule magnet through the relaxation of its nuclear spin bath

A single-molecule magnet placed in a magnetic field perpendicular to its anisotropy axis can be truncated to an effective two-level system, with easily tunable energy splitting. The quantum coherence of the molecular spin is largely determined by the dynamics of the surrounding nuclear spin bath. Here we report the measurement of the nuclear spin-lattice relaxation rate 1/T1n in a single crystal of the single-molecule magnet Mn12-ac, at T ≈ 30 mK in perpendicular fields B⊥ up to 9 T. The relaxation channel at B ≈ 0 is dominated by incoherent quantum tunneling of the Mn12-ac spin S, aided by the nuclear bath itself. However for B⊥>5 T we observe an increase of 1/T1n by several orders of magnitude up to the highest field, despite the fact that the molecular spin is in its quantum mechanical ground state. This striking observation is a consequence of the zero-point quantum fluctuations of S, which allow it to mediate the transfer of energy from the excited nuclear spin bath to the crystal lattice at much higher rates. Our experiment highlights the importance of quantum fluctuations in the interaction between an "effective two-level system" and its surrounding spin bath.

Yessotoxin induces ER-stress followed by autophagic cell death in glioma cells mediated by mTOR and BNIP3

Yessotoxin at nanomolar concentrations can induce programmed cell death in different model systems. Paraptosis-like cell death induced by YTX in BC3H1 cells, which are insensitive to several caspase inhibitors,has also been reported. This makes yessotoxin of interest in the search of molecules that target cancer cells vulnerabilities when resistance to apoptosis is observed. To better understand the effect of this molecule at the molecular level on tumor cells, we conducted a transcriptomic analysis using 3 human glioma cell lines with different sensitivities to yessotoxin. We show that the toxin induces a deregulation of the lipid metabolism in glioma cells as a consequence of induction of endoplasmic reticulum stress. The endoplasmic reticulum stress in turn arrests the cell cycle and inhibits the protein synthesis. In the three cell lines used we show that YTX induces autophagy, which is involved in cell death. The sensibility of the cell lines used towards autophagic cell death was related to their doubling time, being the cell line with the lowest proliferation rate the most resistant.The involvement of mTOR and BNIP3 in the autophagy induction was also determined.

Stictonectes abellani sp. n. (Coleoptera: Dytiscidae: Hydroporinae) from the Iberian Peninsula, with notes on the phylogeny, ecology and distribution of the Iberian species of the genus

Stictonectes abellani sp. n. is described from the Iberian Peninsula. On average, the new species is larger and the colouration of the upper surface darker than in most other species of the genus. Seemingly the species has been confounded with others in the past, particularly S. optatus (Seidlitz, 1887). Males can be separated from externally similar species by studying the shape of the parameres. Additionally, the anterior margin of the clypeus is provided with a distinct rim in both sexes, which is absent or only weakly present in other species. The habitus and the male genitalia of the new species are illustrated, and compared with those of S. optatus. External morphological differences from other members of the genus are discussed. According to studies of the molecular phylogeny, based on fragments of four mitochondrial genes, S. abellani sp. n. is clearly separated from previously described species of Stictonectes Brinck, 1943, apparently being relatively basal within the genus. The new species is rather widely distributed in the south-western part of the Iberian Peninsula, inhabiting pools in small temporary siliceous streams. We provide distributional maps for all eight Iberian Stictonectes and estimate the potential distributional areas of the new species and the other two endemic Iberian species S. occidentalis Fresneda & Fery, 1990 and S. rebeccae Bilton, 2011, based on environmental niche modelling. 

Water beetle tolerance to salinity and anionic composition and its relationship to habitat occupancy

Water salinity and ionic composition are among the main environmental variables that constrain the fundamental niches of aquatic species, and accordingly, physiological tolerance to these factors constitutes a crucial part of the evolution, ecology, and biogeography of these organisms. The present study experimentally estimated the fundamental saline and anionic niches of adults of two pairs of congeneric saline beetle species that differ in habitat preference (lotic and lentic) in order to test the habitat constraint hypothesis. Osmotic and anionic realised niches were also estimated based on the field occurrences of adult beetle species using Outlying Mean Index analysis and their relationship with experimental tolerances. In the laboratory, all of the studied species showed a threshold response to increased salinity, displaying high survival times when exposed to low and intermediate conductivity levels. These results suggest that these species are not strictly halophilic, but that they are able to regulate both hyperosmotically and hypoosmotically. Anionic water composition had a significant effect on salinity tolerance at conductivity levels near their upper tolerance limits, with decreased species survival at elevated sulphate concentrations. Species occupying lentic habitats demonstrated higher salinity tolerance than their lotic congeners in agreement with the habitat constraint hypothesis. As expected, realised salinity niches were narrower than fundamental niches and corresponded to conditions near the upper tolerance limits of the species. These species are uncommon on freshwater-low conductivity habitats despite the fact that these conditions might be physiologically suitable for the adult life stage. Other factors, such as biotic interactions, could prevent their establishment at low salinities. Differences in the realised anionic niches of congeneric species could be partially explained by the varying habitat availability in the study area. Combining the experimental estimation of fundamental niches with realised field data niche estimates is a powerful method for understanding the main factors constraining species' distribution at multiple scales, which is a key issue when predicting species' ability to cope with global change.

Complete genome analyses of G4P[6] rotavirus detected in Argentinean children with diarrhoea provides evidence of interspecies transmission from swine

Rotaviruses are dynamic pathogens that have been shown to infect multiple species. In 2006, two G4P[6] rotavirus strains with porcine characteristics were detected in Santa Fe, Argentina. To further characterize and determine the origin of these strains, nearly the full length of their genome was sequenced. While most of the genome segments were from porcine origin, the two strains grouped in different phylogenetic clusters in five out of the 11 genes, suggesting two independent interspecies transmission events. This study expands our knowledge of G4 rotavirus and reinforces the use of complete genome analyses as a key tool for diversity and evolution mechanicisms.

How far could the alien boatman Trichocorixa verticalis verticalis spread? Worldwide estimation of its current and future potential distribution

Invasions of alien species are considered among the least reversible human impacts, with diversified effects on aquatic ecosystems. Since prevention is the most cost-effective way to avoid biodiversity loss and ecosystem problems, one challenge in ecological research is to understand the limits of the fundamental niche of the species in order to estimate how far invasive species could spread. Trichocorixa verticalis verticalis (Tvv) is a corixid (Hemiptera) originally distributed in North America, but cited as an alien species in three continents. Its impact on native communities is under study, but it is already the dominant species in several saline wetlands and represents a rare example of an aquatic alien insect. This study aims: i) to estimate areas with suitable environmental conditions for Tvv at a global scale, thus identifying potential new zones of invasion; and ii) to test possible changes in this global potential distribution under a climate change scenario. Potential distributions were estimated by applying a multidimensional envelope procedure based on both climatic data, obtained from observed occurrences, and thermal physiological data. Our results suggest Tvv may expand well beyond its current range and find inhabitable conditions in temperate areas along a wide range of latitudes, with an emphasis on coastal areas of Europe, Northern Africa, Argentina, Uruguay, Australia, New Zealand, Myanmar, India, the western boundary between USA and Canada, and areas of the Arabian Peninsula. When considering a future climatic scenario, the suitability area of Tvv showed only limited changes compared with the current potential distribution. These results allow detection of potential contact zones among currently colonized areas and potential areas of invasion. We also identified zones with a high level of suitability that overlap with areas recognized as global hotspots of biodiversity. Finally, we present hypotheses about possible means of spread, focusing on different geographical scales.

[Study of satisfaction of testicular prosthesis implantation in children]

Testicular absence may cause psychological trauma in children. It can be avoided by placing testicular prosthesis (TP). However there is no consensus on the optimal age of implantation. We evaluate the results of TP implantation and their complications, as well as patient and family satisfaction.

MATERIAL AND METHODS

This is a retrospective study of TP implanted between 2004-2010 in our center. Variables analyzed are: age, size and side, indication, surgical technique, complications and comorbidity. Telephone survey was done by a single interviewer to 50 families.

DATA COLLECTED

general family satisfaction, characteristics of the prosthesis (size, shape, location and consistency), body image and psychological situation of the child, duration of analgesia after surgery, reoperation rate, and family advice to other parents. Statistical analysis with SPSS-18.0.

RESULTS

107 prostheses were placed (4 bilateral, 64 left and 35 rights) at a mean age of 70,10 +/- 58,6 months. The most common indication was cryptorchidism (48.2%). Initial inguinal approach in 69%, and simultaneous contralateral orchidopexy in 29.9%. Only one patient refused the prostheses. In 71% the mother was interviewed. Parents consider size, shape and position appropriate in 55.6%, 66.7% and 82.22% respectively. Hard consistency of TP was considered in 82.3% of the patients. Psychological problems were absent in 86.7%. Nighty five percent would be willing to replace when it was necessary. Parents would recommend the intervention to parents in the same situation in 86.7%.

CONCLUSION

Testicular prosthesis avoids psychological trauma. The lack of satisfaction regarding to the small size and hardness makes necessary to replace the TP in adulthood. An open question remains whether we should consider the placement of TP in early ages, or if we should establish some indications based on a more rational communication with the family.

[Bronchoplastic surgery: tumorectomy in principal left bronchial tube in a 5-month old child]

INTRODUCTION

Resection of bronchial tumors usually needs resection of the lung parenchyma ventilated by the ill bronchus. Surgery over a developing child must preserve the biggest amount of lung parenchyma as possible. We show a complete resection of a benign tumor from the left main-stem bronchus, without pneumonectomy.

MATERIALS AND METHODS

Case report

RESULTS

A 5 month girl presented with left hypoventilation. No significant previous dates. After bronchoscopy (with negative biopsy), chest radiograph and CT, she was diagnosed of a tumor in the mainstem left bronchus (20 x 15 mm) without metastatic extension. A sleeve resection of the tumor, with carinal reconstruction was performed. It was done under unipulmonary ventilation, with selective bronchial intubation. The patient was extubated in the operating room and the hospital stay was of 5 days. Follow up bronchoscopies shows no anastomotic stricture neither leakage. The patient is doing well 2 years after surgery.

CONCLUSIONS

With this report and others in literature we can say that is possible to resect bronchial tumors in infancy without parenchymal resections.

Characterization of EST-derived microsatellites for gene mapping and evolutionary genomics in turbot

The detection of microsatellite sequences within expressed sequence tags (ESTs) connects potential markers with specific genes, generating type I markers. We have developed and mapped by linkage analysis a set of EST-derived microsatellites in the turbot, Scophthalmus maximus. One hundred and ninety-one microsatellites were identified from 9256 turbot ESTs. Primer design was possible with 98 microsatellites. After genotyping 25 wild turbot and the parents of two reference families for linkage analysis, 43 EST-derived microsatellites were selected because they met technical and polymorphism criteria. A final set of 31 EST-derived microsatellites could be mapped to 17 linkage groups of the turbot consensus map based on 242 anonymous microsatellites. Twenty-four microsatellite-containing ESTs were functionally annotated, confirming them as type I markers. Nineteen were mapped in the turbot consensus map. These EST-derived microsatellites constitute useful tools for genome scanning of turbot populations, marker-assisted selection programmes and comparative mapping.