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Global warming is raising concerns about the acclimatory capacity of trees and forests, especially in Mediterranean-type ecosystems. The sensitivity of photosynthesis to temperature is a key uncertainty for projecting the magnitude of terrestrial feedbacks on future climate change. While boreal, temperate and tropical species have been comparatively well investigated, our study provides the first comprehensive overview of the seasonal acclimatory responses of photosynthesis and its component processes to temperature in four Mediterranean climax species under natural conditions. We quantified seasonal changes in the responses of net photosynthesis (A net), stomatal conductance (g s), mesophyllic conductance (g m) and electron-transport rate (J cf), and investigated their sensitivity to drought and temperature stress in sunlit and shaded leaves of four Mediterranean tree species (Quercus ilex L. , Pinus halepensis Mill. , Arbutus unedo L. and Quercus pubescens Willd.). Sunlit leaves, but not shaded leaves, showed a pronounced seasonality in the temperature responses of A net, g s, g m and J cf. All four species and variables showed a remarkably dynamic and consistent acclimation of the thermal optimum (T opt), reaching peaks in summer ~29–32 °C. Changes in the shape of the response curves were, however, highly species-specific. Under severe drought, T opt of all variables were on average 22–29% lower. This was accompanied by narrower response curves above all in P. halepensis , reducing the optimal range for photosynthesis to the cooler morning or evening periods. Wider temperature-response curves and less strict stomatal control under severe drought were accompanied by wilting and drought-induced leaf shedding in Q. ilex and Q. pubescens and by additional branch dieback in A. unedo. Mild winter conditions led to a high T opt (~19.1–22.2 °C), benefitting the evergreen species, especially P. halepensis. Seasonal acclimation of A net was explained better by g s and g m being less pronounced in J cf. Drought was thus a key factor, in addition to growth temperature, to explain seasonal acclimation of photosynthesis. Severe drought periods may exceed more frequently the high acclimatory capacity of Mediterranean trees to high ambient temperatures, which could lead to reduced growth, increased leaf shedding and, for some species such as A. unedo , increased mortality risk. [ABSTRACT FROM AUTHOR]

Background: In the POISE‐2 (PeriOperative ISchemic Evaluation 2) trial, perioperative aspirin did not reduce cardiovascular events, but increased major bleeding. There remains uncertainty regarding the effect of perioperative aspirin in patients undergoing vascular surgery. The aim of this substudy was to determine whether there is a subgroup effect of initiating or continuing aspirin in patients undergoing vascular surgery. Methods: POISE‐2 was a blinded, randomized trial of patients having non‐cardiac surgery. Patients were assigned to perioperative aspirin or placebo. The primary outcome was a composite of death or myocardial infarction at 30 days. Secondary outcomes included: vascular occlusive complications (a composite of amputation and peripheral arterial thrombosis) and major or life‐threatening bleeding. Results: Of 10 010 patients in POISE‐2, 603 underwent vascular surgery, 319 in the continuation and 284 in the initiation stratum. Some 272 patients had vascular surgery for occlusive disease and 265 had aneurysm surgery. The primary outcome occurred in 13·7 per cent of patients having aneurysm repair allocated to aspirin and 9·0 per cent who had placebo (hazard ratio (HR) 1·48, 95 per cent c.i. 0·71 to 3·09). Among patients who had surgery for occlusive vascular disease, 15·8 per cent allocated to aspirin and 13·6 per cent on placebo had the primary outcome (HR 1·16, 0·62 to 2·17). There was no interaction with the primary outcome for type of surgery (P = 0·294) or aspirin stratum (P = 0·623). There was no interaction for vascular occlusive complications (P = 0·413) or bleeding (P = 0·900) for vascular compared with non‐vascular surgery. Conclusion: This study suggests that the overall POISE‐2 results apply to vascular surgery. Perioperative withdrawal of chronic aspirin therapy did not increase cardiovascular or vascular occlusive complications. Registration number: NCT01082874 (http://www.clinicaltrials.gov). No evidence to start or stop aspirin [ABSTRACT FROM AUTHOR]

Terrestrial carbon exchange is a key process of the global carbon cycle consisting of a delicate balance between photosynthetic carbon uptake and respiratory release. We have, however, a limited understanding how long-term decreases in precipitation induced by climate change affect the boundaries and mechanisms of photosynthesis and respiration. We examined the seasonality of photosynthetic and respiratory traits and evaluated the adaptive mechanism of the foliar carbon balance of Quercus ilex L. experiencing a long-term rainfall-exclusion experiment. Day respiration (Rd) but not night respiration (Rn) was generally higher in the drought treatment leading to an increased Rd/Rn ratio. The limitation of mesophyll conductance (gm) on photosynthesis was generally stronger than stomatal limitation (gs) in the drought treatment, reflected in a lower gm/gs ratio. The peak photosynthetic activity in the drought treatment occurred in an atypical favourable summer in parallel with lower Rd/Rn and higher gm/gs ratios. The plant carbon balance was thus strongly improved through: (i) higher photosynthetic rates induced by gm; and (ii) decreased carbon losses mediated by Rd. Interestingly, photosynthetic potentials (Vc,max, Jmax, and TPU) were not affected by the drought treatment, suggesting a dampening effect on the biochemical level in the long term. In summary, the trees experiencing a 14-year-long drought treatment adapted through higher plasticity in photosynthetic and respiratory traits, so that eventually the atypical favourable growth period was exploited more efficiently. [ABSTRACT FROM AUTHOR]

The Mediterranean region is a hot spot of climate change vulnerable to increased droughts and heat waves. Scaling carbon fluxes from leaf to landscape levels is particularly challenging under drought conditions. We aimed to improve the mechanistic understanding of the seasonal acclimation of photosynthesis and morphology in sunlit and shaded leaves of four Mediterranean trees (Quercus ilex L., Pinus halepensis Mill., Arbutus unedo L. and Quercus pubescens Willd.) under natural conditions. Vc,max and Jmax were not constant, and mesophyll conductance was not infinite, as assumed in most terrestrial biosphere models, but varied significantly between seasons, tree species and leaf position. Favourable conditions in winter led to photosynthetic recovery and growth in the evergreens. Under moderate drought, adjustments in the photo/biochemistry and stomatal/mesophyllic diffusion behaviour effectively protected the photosynthetic machineries. Severe drought, however, induced early leaf senescence mostly in A. unedo and Q. pubescens, and significantly increased leaf mass per area in Q. ilex and P. halepensis. Shaded leaves had lower photosynthetic potentials but cushioned negative effects during stress periods. Species-specificity, seasonal variations and leaf position are key factors to explain vegetation responses to abiotic stress and hold great potential to reduce uncertainties in terrestrial biosphere models especially under drought conditions. [ABSTRACT FROM AUTHOR]

The presence of Salmonella spp. and levels of Enterobacteriaceae and aerobic plate count were determined in 300 bovine carcasses randomly collected in an industrial cattle slaughterhouse in Catalonia ( Spain) as part of a control programme to validate good slaughter practices according to Commission Regulation No 2073/2005. The verotoxigenic Escherichia coli O157 ( VTEC O157), although not currently legislated, was also investigated in the same carcasses due to the importance of bovines as a reservoir for this micro-organism. Virulence genes ( vtx1, vtx2 and eae), the presence of fli CH7 and antimicrobial susceptibility were studied in E. coli O157 isolates. Levels of Enterobacteriaceae and aerobic colonies and the presence of Salmonella were within the admissible range stipulated by current legislation. However, VTEC O157 was detected in 14·7% of carcasses. Among the VTEC O157 strains tested for antimicrobial susceptibility, 65% were multiresistant. Overall, the results of this study indicate that even with good manufacturing practices, contamination with VTEC O157 can occur and cattle meat can pose a risk to human health. These results confirm the need for a review of the appropriateness of introducing antimicrobial treatments in the processing of cattle carcasses in Europe. Significance and Impact of the Study This study describes the prevalence of verotoxigenic and multidrug-resistant E. coli O157 strains in bovine carcasses. These results suggest that despite the good manufacturing practices used in the slaughterhouse studied (the largest in Catalonia slaughtering over 81 000 cattle per year), the absence of verotoxigenic E. coli O157 in bovine carcasses cannot be guaranteed. [ABSTRACT FROM AUTHOR]

We used minirhizotrons to determine the vertical distribution of fine roots in a holm oak (Quercus ilex L.) forest in a typical Mediterranean area over a 3-year period (June 1994–March 1997). We measured fine root density (number of roots per unit area), fine root length density (length of roots per unit area), fine root area index (area of roots per unit area) and fine root mean diameter. Variables were pooled for each 10-cm depth interval to a depth of 60 cm. Fine roots tended to decrease with increasing depth except between 0 and 10 cm, where the values of all fine root variables were less than in the 10-cm stratum below. Fine root vertical distribution was compared with soil water content and soil temperature at different depths in the soil profile. [ABSTRACT FROM PUBLISHER]