An additional set of phages to characterize epidemic methicillin-resistant Staphylococcus aureus strains from Spain (1989-92).

In recent years, methicillin-resistant Staphylococcus aureus (MRSA) isolates in Spain have increased dramatically; in 1986 there were only 1.2% MRSA amongst all nosocomial Staphylococcus aureus (SA) isolates, by 1989 this percentage had risen to 44% in some hospital causing a very serious epidemic situation in the country. We have characterized these isolates by direct, reverse and Fisk phage typing and we have also looked for an additional local set of phages to help us to differentiate these strains. We have been able to differentiate an epidemic strain from other MRSA strains which cause sporadic hospital outbreaks, and we have also distinguished between some variants of the epidemic strain.This research has been supported by a grant from the Fondo de Investigaciones Sanitarias de la Seguridad Social (FISS), Ministerio de Sanidad y Consumo, Spain; No. 93/0144.S

Inheritance of DNA methylation differences in the mangrove Rhizophora mangle

The capacity to respond to environmental challenges ultimately relies on phenotypic variation which manifests from complex interactions of genetic and nongenetic mechanisms through development. While we know something about genetic variation and structure of many species of conservation importance, we know very little about the nongenetic contributions to variation. Rhizophora mangle is a foundation species that occurs in coastal estuarine habitats throughout the neotropics where it provides critical ecosystem functions and is potentially threatened by anthropogenic environmental changes. Several studies have documented landscape-level patterns of genetic variation in this species, but we know virtually nothing about the inheritance of nongenetic variation. To assess one type of nongenetic variation, we examined the patterns of DNA sequence and DNA methylation in maternal plants and offspring from natural populations of R. mangle from the Gulf Coast of Florida. We used a reduced representation bisulfite sequencing approach (epi-genotyping by sequencing; epiGBS) to address the following questions: (a) What are the levels of genetic and epigenetic diversity in natural populations of R. mangle? (b) How are genetic and epigenetic variation structured within and among populations? (c) How faithfully is epigenetic variation inherited? We found low genetic diversity but high epigenetic diversity from natural populations of maternal plants in the field. In addition, a large portion (up to ~25%) of epigenetic differences among offspring grown in common garden was explained by maternal family. Therefore, epigenetic variation could be an important source of response to challenging environments in the genetically depauperate populations of this foundation species.</p

Inheritance of DNA methylation differences in the mangrove Rhizophora mangle

The capacity to respond to environmental challenges ultimately relies on phenotypic variation which manifests from complex interactions of genetic and nongenetic mechanisms through development. While we know something about genetic variation and structure of many species of conservation importance, we know very little about the nongenetic contributions to variation. Rhizophora mangle is a foundation species that occurs in coastal estuarine habitats throughout the neotropics where it provides critical ecosystem functions and is potentially threatened by anthropogenic environmental changes. Several studies have documented landscape-level patterns of genetic variation in this species, but we know virtually nothing about the inheritance of nongenetic variation. To assess one type of nongenetic variation, we examined the patterns of DNA sequence and DNA methylation in maternal plants and offspring from natural populations of R. mangle from the Gulf Coast of Florida. We used a reduced representation bisulfite sequencing approach (epi-genotyping by sequencing; epiGBS) to address the following questions: (a) What are the levels of genetic and epigenetic diversity in natural populations of R. mangle? (b) How are genetic and epigenetic variation structured within and among populations? (c) How faithfully is epigenetic variation inherited? We found low genetic diversity but high epigenetic diversity from natural populations of maternal plants in the field. In addition, a large portion (up to ~25%) of epigenetic differences among offspring grown in common garden was explained by maternal family. Therefore, epigenetic variation could be an important source of response to challenging environments in the genetically depauperate populations of this foundation species.Peer reviewe

Matching times: Trying to improve the correlation between heavy metal levels in mosses and bulk deposition

The relationship between the concentrations of metals in moss tissues and atmospheric deposition is highly complex, resulting in a general lack of correlations between these two matrices. Here, we tried to improve the significance of the moss-bulk deposition (BD) relationship by eliminating the mismatch between the time that the moss tissue selected for analysis is exposed to atmospheric deposition, and the time during which BD is collected. For this, we analysed the concentrations of Cd, Hg and Pb in new grown tissue of Pseudoscleropodium purum and BD collected monthly, for one year, in 21 sampling sites (SS) under different degrees of pollution. Additionally, we assessed how different moss tissues, including native moss (green parts and new grown tissues of P. purum) and moss transplants of Sphagnum denticulatum, reflect BD to find out which moss tissues provide a better estimate of the atmospheric deposition of heavy metals. First of all, our results showed that eliminating the mismatch between native moss exposure time and BD collection period is not enough to improve their correlation. Environmental variation emerged as the main driver of tissue content variation altering the moss-BD relationship unpredictably. Secondly, native P. purum represents BD values better than devitalized transplants by displaying a greater number of significant correlations with BD. Specifically, green parts of P. purum generally represent better BD than new grown tissues. Overall, we conclude that neither native mosses nor transplants are good estimators of atmospheric heavy metal deposition rates. However, they are good qualitative indicators of the atmospheric deposition, by allowing us to differentiate SS subject to a wide range of pollution levels. Additionally, green parts of P. purum, and likely of other mosses with similar growth forms, should be used in passive biomonitoring studies to make results from different studies comparable.Peer reviewe

Phenotypic differences in heavy metal accumulation in populations of the brown macroalgae Fucus vesiculosus: A transplantation experiment

The concentrations of Al, As, Cd, Co, Cr, Cu, Fe, Hg, Ni, Pb and Zn in the thalli of Fucus vesiculosus transplanted reciprocally among four sites affected by different degrees of metal pollution (two unpolluted and two industrial environments) were measured with the aim of comparing the capacity of the algae to accumulate these elements under such conditions. At the beginning of the experiment, the concentrations of all elements differed significantly between the individuals from at least one of the unpolluted and one of the polluted sites. After exposure of the algae for 90 days, the concentrations of all of the elements except As, Cd and Cu in individuals transplanted from the unpolluted sites to the most polluted site increased to higher levels than in the algae transplanted within the site of origin. The same behaviour was observed for all elements except As and Cd in the thalli transplanted from one of the unpolluted sites to the second most polluted site. By contrast, the concentrations of the elements in transplants from the polluted sites exposed in the unpolluted sites usually decreased to approximately the same levels as in the autotransplants. These results suggest that the heavy metal uptake capacity may be limited in F. vesiculosus populations exposed to long-term pollution as an adaptive response to toxicity by metals. We therefore recommend the use of algal transplants to study water quality in highly polluted sites, rather than of native algae already growing in the sites, to avoid the possible effects of such adaptation

Patterns and mechanisms of heavy metal accumulation and tolerance in two terrestrial moss species with contrasting habitat specialization

Anthropogenic activities have increased exposure to heavy metal pollution in previously uncontaminated ecosystems, threatening plant communities. Considering that phenotypic variation underlies rapid adjustment to challenging environmental conditions in natural populations, the study of variation in traits related to plant response to heavy metal stress provides valuable insight into the likelihood of a population's survival. This paper investigates patterns of intraspecific phenotypic variation for heavy metal accumulation and tolerance in bryophytes, one of the most resilient and relatively understudied plant taxa. We examined two moss species with contrasting affinities for heavy metals: the heavy metal specialist Scopelophila cataractae, and the facultative metallophyte Ceratodon purpureus. We sampled four populations of S. cataractae in close microhabitats with different contamination levels of Cd and Cu, one population of C. purpureus in an urban area, and separate lab-maintained male and female isolates from one population of C. purpureus growing in axenic conditions. After clonally propagating all populations under control, Cd and Cu treatments, we measured plant fitness, oxidative damage, and Cd and Cu accumulation. Scopelophila cataractae isolates from microhabitats with higher levels of metals in the field (Sc2, Sc3) were more tolerant than those collected in less contaminated microhabitats (Sc1, Sc4). Sc2 and Sc3 accumulated significantly less Cu in the leaves compared to the stem which could limit damage to their main photosynthetic organs and contribute to the observed differences in Cu tolerance. In contrast C. purpureus showed intraspecific differences in tolerance to Cd and Cu, but not in accumulation. These differences arose among isolates that had never been exposed to heavy metals before. We also report the first evidence for sexual dimorphism for Cd tolerance in this species, with females being more tolerant than males. Altogether, our results provide novel insights into the mechanisms used by bryophytes to deal with heavy metal stress, as well as the first evidence for metal-dependent, sex-specific differences in heavy metal tolerance in bryophytes

Epigenetic Approaches in Non-Model Plants

Reduced representation bisulfite sequencing is an emerging methodology for evolutionary and ecological genomics and epigenomics research because it provides a cost-effective, high-resolution tool for exploration and comparative analysis of DNA methylation and genetic variation. Here we describe how digestion of genomic plant DNA with restriction enzymes, subsequent bisulfite conversion of unmethylated cytosines, and final DNA sequencing allow for the examination of genome-wide genetic and epigenetic variation in plants without the need for a reference genome. We explain how the use of several combinations of barcoded adapters for the creation of highly multiplexed libraries allows the inclusion of up to 144 different samples/individuals in only one sequencing lane.</p

Empleo de criptógamas como herramienta ecológica de biomonitorización de nitrógeno en la península ibérica

Nitrogen is an important macronutrient for all living organisms. However, the increased nitrogen inputs in natural ecosystems generate diverse problems, such as eutrophication and acidification and changes in communities. The main scope of the present review is to describe the effects of the increase of the anthropogenic reactive nitrogen (N) on communities of cryptogams (bryophytes and lichens), a key component of many ecosystems. We also aim to evaluate the utility of these organisms as biomonitors of the atmospheric deposition of this nutrient and pollutant in the Iberian Peninsula. Cryptogams are sensitive to N increases in the environment, and for this reason they have already been successfully used as bioindicators of N pollution in the Iberian Peninsula. Besides, they accumulate N in their tissues providing information on the surpassing of critical thresholds and on the sources of the deposited N by means of the N isotopic relationship (δ15N). Finally, we review their main morpho-functional traits, their role in the N cycle, how they are affected by the deposition of anthropogenic N, and we also analyse their potential in biomonitoring, especially through a case study in the Iberian Peninsula using terrestrial mosses.El nitrógeno (N) es un macronutriente vital para los organismos vivos. Sin embargo, su entrada en grandes cantidades genera problemas como la eutrofización y acidificación del medio y cambios en las comunidades. El principal objetivo de esta revisión es describir los posibles efectos que produce el aumento antropogénico del N reactivo en las comunidades de criptógamas (briófitos y líquenes), un componente clave de muchos ecosistemas. Pretendemos, además, evaluar la utilidad de dichos organismos como biomonitores del depósito de este nutriente y contaminante en la Península ibérica. Las criptógamas son organismos sensibles al incremento de N en el medio, por lo que se han empleado ya con éxito en la Península ibérica como bioindicadores de la contaminación por N. Por otro lado, son capaces de acumular N, proporcionando información sobre la superación de umbrales críticos en los ecosistemas y del origen de las emisiones del N depositado mediante la relación isotópica del N (δ15N). Finalmente, revisamos las principales características morfo-funcionales de los organismos mencionados, su papel en el ciclo del N, los efectos que sufren por el depósito de N antropogénico, y analizamos su potencial como biomonitores, tanto en general como a través de un caso práctico desarrollado en la península ibérica empleando musgos terrestres

Genetic structuring of the moss Pseudoscleropodium purum sampled at different distances from a pollution source

In this study, we used amplified fragment length polymorphism analysis to investigate the genetic structure of the terrestrial moss Pseudoscleropodium purum (Hedw.) M. Fleish. naturally exposed to different levels of atmospheric deposition of heavy metals. We also determined the heavy metal concentrations in samples of this moss to evaluate whether there was a relationship between atmospheric pollution and population genetic diversity. A low level of genetic diversity and a limited gene flow among populations were observed which is in accordance to the prevalence of asexual reproduction in this species. In addition, no significant correlation was found between metal content and gene diversity in P. purum, probably because of the common history of the sampled populations and/or to the lack of a drastic reduction of the size of the population; nonetheless, a clear genetic structure was evident in relation to the existing pollution gradient. Thus, based on the results of the principal coordinate analysis and Bayesian analysis of the genotypes, the mixed structure of the second most polluted population would suggest an ongoing differentiation of metal-tolerant genotypes in the most polluted sites of the sampling area

Molecular basis of intraspecific differentiation for heavy metal tolerance in the copper moss Scopelophila cataractae

The remarkable capacity of bryophytes to tolerate extremely challenging abiotic conditions allows us to enhance our understanding of the diversity of molecular mechanisms involved in plant stress response. Here, we used next generation sequencing to study DNA methylation and gene expression changes in plants from four populations of the metallophyte moss Scopelophila cataractae experimentally exposed to either Cd or Cu. These populations previously showed differences in tolerance to both metals, so here, we aimed to investigate the molecular basis of this phenotypic differentiation. We found no evidence of genetic differentiation among the populations studied. The epigenetic data, however, showed limited but significant population-specific changes in DNA methylation in response to both metals. Exposure to acute Cu stress in the laboratory led to the downregulation of genes involved in heavy metal tolerance in both the more and the less tolerant populations, but this response was quantitatively higher in the most tolerant. We propose that chronic exposure to varying levels of heavy metals in the field led to potentially non-genetically-based intraspecific differentiation for heavy metal tolerance in S. cataractae. The most tolerant plants invested more in constitutive protection and were more efficient at entering a conservative state when faced with acute Cu stressThis research has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No 704141-BryOmics. Dr. M. Teresa Boquete has been supported during the development of this project by the Juan de la Cierva-Incorporación program from the Spanish Ministry of Science, Innovation and Universities (IJC2018-035018) and is currently supported by the Maria Zambrano program from the Spanish Ministry of Science, Innovation and UniversitiesS