Tissue culture of ornamental cacti

Cacti species are plants that are well adapted to growing in arid and semiarid regions where the main problem is water availability. Cacti have developed a series of adaptations to cope with water scarcity, such as reduced leaf surface via morphological modifications including spines, cereous cuticles, extended root systems and stem tissue modifications to increase water storage, and crassulacean acid metabolism to reduce transpiration and water loss. Furthermore, seeds of these plants very often exhibit dormancy, a phenomenon that helps to prevent germination when the availability of water is reduced. In general, cactus species exhibit a low growth rate that makes their rapid propagation difficult. Cacti are much appreciated as ornamental plants due to their great variety and diversity of forms and their beautiful short-life flowers; however, due to difficulties in propagating them rapidly to meet market demand, they are very often over-collected in their natural habitats, which leads to numerous species being threatened, endangered or becoming extinct. Therefore, plant tissue culture techniques may facilitate their propagation over a shorter time period than conventional techniques used for commercial purposes; or may help to recover populations of endangered or threatened species for their re-introduction in the wild; or may also be of value to the preservation and conservation of the genetic resources of this important family. Herein we present the state-of-the-art of tissue culture techniques used for ornamental cacti and selected suggestions for solving a number of the problems faced by members of the Cactaceae family

Data Descriptor : A European Multi Lake Survey dataset of environmental variables, phytoplankton pigments and cyanotoxins

Under ongoing climate change and increasing anthropogenic activity, which continuously challenge ecosystem resilience, an in-depth understanding of ecological processes is urgently needed. Lakes, as providers of numerous ecosystem services, face multiple stressors that threaten their functioning. Harmful cyanobacterial blooms are a persistent problem resulting from nutrient pollution and climate-change induced stressors, like poor transparency, increased water temperature and enhanced stratification. Consistency in data collection and analysis methods is necessary to achieve fully comparable datasets and for statistical validity, avoiding issues linked to disparate data sources. The European Multi Lake Survey (EMLS) in summer 2015 was an initiative among scientists from 27 countries to collect and analyse lake physical, chemical and biological variables in a fully standardized manner. This database includes in-situ lake variables along with nutrient, pigment and cyanotoxin data of 369 lakes in Europe, which were centrally analysed in dedicated laboratories. Publishing the EMLS methods and dataset might inspire similar initiatives to study across large geographic areas that will contribute to better understanding lake responses in a changing environment.Peer reviewe

Temperature Effects Explain Continental Scale Distribution of Cyanobacterial Toxins

Insight into how environmental change determines the production and distribution of cyanobacterial toxins is necessary for risk assessment. Management guidelines currently focus on hepatotoxins (microcystins). Increasing attention is given to other classes, such as neurotoxins (e.g., anatoxin-a) and cytotoxins (e.g., cylindrospermopsin) due to their potency. Most studies examine the relationship between individual toxin variants and environmental factors, such as nutrients, temperature and light. In summer 2015, we collected samples across Europe to investigate the effect of nutrient and temperature gradients on the variability of toxin production at a continental scale. Direct and indirect effects of temperature were the main drivers of the spatial distribution in the toxins produced by the cyanobacterial community, the toxin concentrations and toxin quota. Generalized linear models showed that a Toxin Diversity Index (TDI) increased with latitude, while it decreased with water stability. Increases in TDI were explained through a significant increase in toxin variants such as MC-YR, anatoxin and cylindrospermopsin, accompanied by a decreasing presence of MC-LR. While global warming continues, the direct and indirect effects of increased lake temperatures will drive changes in the distribution of cyanobacterial toxins in Europe, potentially promoting selection of a few highly toxic species or strains.Peer reviewe

Stratification strength and light climate explain variation in chlorophyll a at the continental scale in a European multilake survey in a heatwave summer

To determine the drivers of phytoplankton biomass, we collected standardized morphometric, physical, and biological data in 230 lakes across the Mediterranean, Continental, and Boreal climatic zones of the European continent. Multilinear regression models tested on this snapshot of mostly eutrophic lakes (median total phosphorus [TP] = 0.06 and total nitrogen [TN] = 0.7 mg L−1), and its subsets (2 depth types and 3 climatic zones), show that light climate and stratification strength were the most significant explanatory variables for chlorophyll a (Chl a) variance. TN was a significant predictor for phytoplankton biomass for shallow and continental lakes, while TP never appeared as an explanatory variable, suggesting that under high TP, light, which partially controls stratification strength, becomes limiting for phytoplankton development. Mediterranean lakes were the warmest yet most weakly stratified and had significantly less Chl a than Boreal lakes, where the temperature anomaly from the long-term average, during a summer heatwave was the highest (+4°C) and showed a significant, exponential relationship with stratification strength. This European survey represents a summer snapshot of phytoplankton biomass and its drivers, and lends support that light and stratification metrics, which are both affected by climate change, are better predictors for phytoplankton biomass in nutrient-rich lakes than nutrient concentrations and surface temperature

Entre kronos e kairós: o sentido e as implicações da ampliação do tempo de permanência dos estudantes na escola

Este artigo apresenta um recorte dos resultados de uma pesquisa desenvolvida nacionalmente - Educação Integral em Tempo Integral no Ensino Fundamental: Concepções e Práticas na Educação Brasileira - que analisou as experiências de ampliação da jornada escolar em diferentes regiões do Brasil. Nesse contexto, a análise das experiências escolares desenvolvidas nos estados do Rio Grande do Sul, Santa Catarina e Paraná foi a base que permitiu estabelecer um diálogo entre empiria e teoria para a compreensão dos sentidos e das implicações do uso e da ampliação do tempo educativo escolar. Neste diálogo, procuramos compreender o impacto provocado pelas modificações na jornada escolar tradicional, de quatro horas diárias, sem a participação efetiva e constante de outros agentes formativos. O processo de análise dos dados tratou de identificar as mudanças na organização e no funcionamento das escolas, bem como na relação dessas com suas comunidades. Mais do que pensar em horários e rotinas, buscou-se pensar em horas concretas, em períodos de permanência dos estudantes nas comunidades escolares e no sentido que essa presencialidade adquire para os envolvidos nesse processo e para a própria sociedade

Incidencia de la jornada escolar en los procesos de socialización infantil School day incidence on children´s socialization processes

El artículo, derivado de la tesis doctoral realizada por la autora, sitúa el punto de análisis en la percepción del tiempo social en general, y particularmente el escolar, como una realidad materializada en significados diversos para las niñas y niños, generadores de tensiones y conflictos en los procesos de socialización infantil. La vida cotidiana de la infancia en sus contextos familiar, extrafamiliar y escolar, está fuertemente mediatizada por las demandas y presiones del tiempo escolar que preside y organiza la vida de los pequeños y sus familias. El artículo analiza esta incidencia tomando como variable fundamental la modalidad de jornada lectiva, unidad temporal que ha usurpado el debate sobre la globalidad de los tiempos escolares y educativos que es, no sólo deseable, sino urgente en el contexto español. En el estudio se aportan los resultados obtenidos en la investigación realizada con alumnado gallego de Educación Primaria, alrededor de las siguientes cuestiones: planificación, administración y gestión del tiempo; percepción de su transcurrir y valoración de su disponibilidad y uso en los ámbitos familiar, escolar y extraescolar. La variable modalidad de jornada escolar (sesión única matinal/sesión partida mañana y tarde) se ha tomado como principal referencia en el análisis.<br>The paper, derived of the Dissertation realised by the author, situates the point of analysis in the perception of social time in general, and particularly in school time, like a reality materialised in diverse meanings for girls and boys, generators of tensions and conflicts in the processes of chilhood socialization. Daily life of childhood in his familiar, extrafamiliar and school contexts, is strongly influenced by the demands and pressures of the time at school that prevailes and organises the life of children and their families. The paper analyzes this incidence taking the modality of the school day as a fundamental variable, temporary unit that has usurped the debate on the entirety of the school time and the educational time that it is, not only desirable, but urgent in the Spanish context. In the study, we show the results obtained in the investigation realised with Galician students of Primary Education, around the following questions: planning, administration and management of time; perception of how time goes and the assessment of his availability and use in the family, school and extraescolar fields. The modality of the school day (only morning session /session split morning and afternoon) variable, has taken the main reference in the analysis

Pancreatic islet enhancer clusters enriched in type 2 diabetes risk-associated variants.

Type 2 diabetes affects over 300 million people, causing severe complications and premature death, yet the underlying molecular mechanisms are largely unknown. Pancreatic islet dysfunction is central in type 2 diabetes pathogenesis, and understanding islet genome regulation could therefore provide valuable mechanistic insights. We have now mapped and examined the function of human islet cis-regulatory networks. We identify genomic sequences that are targeted by islet transcription factors to drive islet-specific gene activity and show that most such sequences reside in clusters of enhancers that form physical three-dimensional chromatin domains. We find that sequence variants associated with type 2 diabetes and fasting glycemia are enriched in these clustered islet enhancers and identify trait-associated variants that disrupt DNA binding and islet enhancer activity. Our studies illustrate how islet transcription factors interact functionally with the epigenome and provide systematic evidence that the dysregulation of islet enhancers is relevant to the mechanisms underlying type 2 diabetes