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Rubisco is the main CO2-fixing enzyme in the biosphere and sustains the vast majority of food chains on Earth. Although Rubisco catalysis is currently an area of active study, there is still a strong debate about the main drivers shaping Rubisco evolution. Thus, an integrative and complete meta-analysis of study-to-study normalized Rubisco kinetic data becomes an essential requisite to succeed in providing new relevant information on Rubisco phylogenetic evolution and environmental adaptation. The aim of this study was to undertake an exhaustive compilation of all the data published so far on the in vitro Rubisco catalytic parameters of autotrophic organisms containing Rubisco, from bacteria to vascular plants. Rubisco evolution was re-evaluated in the context of its environmental drivers and the effectiveness of CO2 concentrating mechanisms (CCMs). The phylogenetic signal in Rubisco catalysis was also analyzed by evaluating the dependence of variation in kinetic traits on the phylogenetic tree constructed from the Rubisco large subunit sequence. Our results showed that phylogenetic constraints in Rubisco adaptation mostly determine the specificity factor values of current species. However, the adaptation of the Rubisco affinity for CO2 and carboxylation efficiency has been more influenced by the environmental conditions than by phylogenetic constraints, either provoking an evolution of a more CO2-affine and efficient Rubisco enzyme under limiting intracellular CO2 conditions, or a relaxation of CO2 affinity and efficiency when co-evolved with CCMs. Importantly, this analysis questions the canonical trade-off between Rubisco kinetic traits previously described for Spermatophyta and recognizes a larger plasticity of Rubisco kinetics than previously thought. This information will be especially useful for understanding the effects in the productivity and ecological success of the different aquatic organisms in future scenarios of Global Change.

The coccolithophore Emiliania huxleyi shows a variety of responses to ocean acidification (OA) and to high-CO2 concentrations, but there is still controversy on differentiating between these two factors when using different strains and culture methods. A heavily calcified type A strain isolated from the Norwegian Sea was selected and batch cultured in order to understand whether acclimation to OA was mediated mainly by CO2 or H+, and how it impacted cell growth performance, calcification, and physiological stress management. Emiliania huxleyi responded differently to each acidification method. CO2-enriched aeration (1200 µatm, pH 7.62) induced a negative effect on the cells when compared to acidification caused by decreasing pH alone (pH 7.60). The growth rates of the coccolithophore were more negatively affected by high pCO2 than by low pH without CO2 enrichment with respect to the control (400 µatm, pH 8.1). High CO2 also affected cell viability and promoted the accumulation of reactive oxygen species (ROS), which was not observed under low pH. This suggests a possible metabolic imbalance induced by high CO2 alone. In contrast, the affinity for carbon uptake was negatively affected by both low pH and high CO2. Photochemistry was only marginally affected by either acidification method when analysed by PAM fluorometry. The POC and PIC cellular quotas and the PIC:POC ratio shifted along the different phases of the cultures; consequently, calcification did not follow the same pattern observed in cell stress and growth performance. Specifically, acidification by HCl addition caused a higher proportion of severely deformed coccoliths, than CO2 enrichment. These results highlight the capacity of CO2 rather than acidification itself to generate metabolic stress, not reducing calcification. Open Access funding provided thanks to the CRUE-CSIC agreement with Springer Nature. Funding for open access charge: Universidad de Málaga / CBUA This work was funded by FC14-RNM-27 research grant (FITOVIA) from the University of Málaga, Spain (Plan Propio) to CJ. VV was funded by a EUROPE ERASMUS+grant to carry out research short-stay at Marine Scotland Marine Laboratory in Aberdeen, UK, and by a grant from the University of Málaga, Spain (Plan Propio).

The coccolithophore Emiliania huxleyi shows a variety of responses to ocean acidification (OA) and to high-CO

Warming is affecting Kongsfjorden ecosystem with special intensity due to the influence of oceanic currents altered by Global Change. The effects of this stressor on the ecophysiology of Arctic seaweeds have been widely investigated, but mostly restricted to summer. However, Arctic coastal ecosystems experience strong seasonal changes in environmental light conditions from 24-hours of darkness in winter to 24-hours of light in summer, which likely alter the photosynthetic performance of macroalgae. In order to understand how increasing temperature will affect Kongsfjorden ecosystem dynamics it is crucial to analyze the effect of seasonal photoperiod on the responses of Arctic seaweeds to warming. Thus, we carried out experiments in September (fall equinox), March (spring equinox) and August (24h of light) to compare the photophysiological responses of common seaweed species of Kongsfjorden after acclimation to continuous light and 12:12 light:darkness at 4ºC, as well as the responses to increased temperature (8ºC) at the corresponding seasonal photoperiod. Due to 24-hours light stress in summer, macroalgae generally showed reduced photosynthetic capacity when compared to the equinoxes. Additionally, higher photoinhibition along with higher respiration rates were induced when seaweeds were exposed to continuous light in the equinoxes, whereas macroalgae exposed to 12:12 light/dark cycles in summer showed no changes in the photosynthetic capacities and respiratory rates. The increase in temperature frequently enhanced 14CO2 fixation and respiration rates, while growth rates were mostly unaltered, but season-specific and species-specific effects were observed. These results are highly valuable for constructing primary productivity models of the macrophytobenthos for the whole fjord, which can serve to make accurate predictions of productivity and ecosystem functioning in near-future scenarios. Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech.

The effect of temperature and photoperiod along the year on the composition of 5 macroalgal species representative of the sublittoral system of Kongsfjorden was studied in laboratory conditions. These species were the ochrophytes Saccharina latissima and Alaria esculenta, the rhodophytes Phycodrys rubens and Ptilota gunneri, and the chlorophyte Monostroma aff. arcticum (only present from summer to early autumn). Three different seasons were compared: early March, early August and late September. Two temperatures were tested (4 and 8°C) as well as continuous irradiation (CL - simulating summer) and 12:12 h light:dark photoperiod (simulating equinoxes). Total carbon was not affected by warming or photoperiod, except in S. latissima in autumn under CL and 4°C, being 40% higher than with photoperiod. Nitrogen content generally increased by photoperiod, the highest being found in 12:12 L/D in all seasons. Carbohydrates were maximal in CL conditions in all species, indicating that their synthesis is light-stimulated, mainly in the equinoxes. In general, warming did not induce significant changes in carbohydrate content. Lipid content was affected by photoperiod only in brown algae. In S. latissima lipids presented maximum values in CL in the autumn equinox, while in A. esculenta was under photoperiod in summer. Protein content did not change with warming or photoperiod in three out of the five species, and only in S. latissima and P. gunneri proteins were higher in CL than under photoperiod in the autumn equinox. In summary, the results indicate that only isolated changes in the composition of these representative macrophytes may be expected under warming conditions in near-future scenarios, while a general increase in carbon, carbohydrates and proteins under CL was observed mainly in the autumn equinox. The relation of this increase with light utilisation performance will be discussed. Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech. Proyecto MACROARTES, CGL2015-67014-R.

Levels of natural and anthropogenic radionuclides have been determined in six brown and red seaweed species from Arctic coasts (Kongsfjorden, Spitsbergen, Svalbard Islands) in order to characterize the radioactivity in this ecosystem. Samples were collected in September 2014, August 2017 and July 2019. Levels of 7Be, 40K, 208Tl, 210Pb, 226Ra and 228Ra were measured by high-resolution gamma spectrometry. While anthropogenic radionuclides (1 4 C and 1 2 9 I) were determined by low-energy accelerator mass spectrometry (LEAMS). The activities of 129I are two orders of magnitude higher than those found in algae collected on the Spanish Atlantic Coast and presents more variability than the 14C results, indicating their different affinity to this element depending on the species. Radionuclide tracers discharged from Sellafield and La Hague are transported into the Arctic Ocean where they circulate at different depth levels, marking water of Atlantic origin (Karcher et al., 2012). Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech. Proyecto CGL2015/67014R

El grupo BEIR VII (Efectos Biológicos de Radiación Ionizante de la Academia Nacional de Ciencias de los Estados Unidos) ha actualizado las estimaciones previas de riesgo de incidencia de cáncer inducido por radiación y mortalidad, incluida la dependencia de ambos riesgos. A la luz de estas nuevas estimaciones del riesgo de radiación, parece oportuno volver a evaluar y resumir las dosis de radiación y los riesgos de cáncer asociados con todas las modalidades de imágenes de mama que implican el uso de radiación ionizante El objetivo principal del presente trabajo es la estimación de la dosis glandular media (DGM) de las mamografías realizadas en España (2011-2013). Este análisis se ha llevado a cabo mediante el estudio de frecuencias, dosis glandular media, dosis efectiva media y dosis colectiva aportada por las mamografías en más de 30 hospitales de España. Entre los resultados obtenidos, destacar la frecuencia anual de mamografías en España (4.203.661) de las cuales un 57% corresponden a las realizadas en screening, frente al 43% de las diagnósticas, basados en datos del proyecto DOPOES. La DGM (valor promedio) en España se estima que es de 1,51 mGy por cada mama. Estos valores están en consonancia con el BEIR VII con valores medios estimados de MGD por mama de 1,78 mGy (equipos digitales) y de 2,35 mGy (equipos analógicos). Asimismo, se presentará el riesgo atribuible durante toda la vida (LAR) por grupos de edad en las mujeres que se han realizado mamografías. CONSEJO DE SEGURIDAD NUCLEAR UNIVERSIDAD DE MALAGA

The continuous discharge of sewage with significant nutrient loads into coastal waters, is causing a dramatic deterioration of the environment due to eutrophication processes. Actually, some practices are being taken into account in aquaculture as the integration of seaweed in fish-farming to control the level of nutrients generated. In order to study the capability of macroalgae for removing nutrients, six species of the Mediterranean Coast of Southern Europe (Corallina elongata, Ulva olivascens, Halopteris scoparia, Cystoseira mediterranea, Laurencia pinnatifida and Enteromorpha sp.) were studied in laboratory experiments. The specimens were incubated in different external nutrient load conditions to determine the uptake rate of nitrate and phosphate, and the internal concentrations of these species were analysed to obtain the concentration factor for both nutrients. The results obtained show that these algae remove nutrients efficiently from the medium and the uptake rates follow saturation kinetics in normal conditions. U.olivascens had the highest uptake rate for both nitrate and phosphate while C.elongata and H.scoparia had the highest concentration factor for nitrate and phosphate respectively. These results indicate that integration of these species in intensive fish-farming may play an increasingly important role as a nutrient-removal system, alleviating eutrophication problems due to fed aquaculture.