Climate seasonality limits leaf carbon assimilation and wood productivity in tropical forests

The seasonal climate drivers of the carbon cycle in tropical forests remain poorly known, although these forests account for more carbon assimilation and storage than any other terrestrial ecosystem. Based on a unique combination of seasonal pan-tropical data sets from 89 experimental sites (68 include aboveground wood productivity measurements and 35 litter productivity measurements), their associated canopy photosynthetic capacity (enhanced vegetation index, EVI) and climate, we ask how carbon assimilation and aboveground allocation are related to climate seasonality in tropical forests and how they interact in the seasonal carbon cycle. We found that canopy photosynthetic capacity seasonality responds positively to precipitation when rainfall is  < 2000 mm yr⁻¹ (water-limited forests) and to radiation otherwise (light-limited forests). On the other hand, independent of climate limitations, wood productivity and litterfall are driven by seasonal variation in precipitation and evapotranspiration, respectively. Consequently, light-limited forests present an asynchronism between canopy photosynthetic capacity and wood productivity. First-order control by precipitation likely indicates a decrease in tropical forest productivity in a drier climate in water-limited forest, and in current light-limited forest with future rainfall  < 2000 mm yr⁻¹

New dietary records and geographic variation in the diet composition of the snake Philodryas nattereri in Brazil

In this study, we report new dietary data about the South American dipsadine snake Philodryas nattereri in the Caatinga ecoregion of northeastern Brazil. Our observations in the wild include predation on a large-sized lizard, an adult bird, venomous toads, a snake, bird chicks inside nests, and a mammal. Besides that, we compared the diet composition of P. nattereri between the Caatinga and the Cerrado ecoregions of Brazil, by pooling our original data with all available literature records. We found a significant difference in the diet of P. nattereri between these two regions: lizards comprise the predominant prey category for P. nattereri in the Caatinga, whereas mammals stand out as the most reported prey in the Cerrado. Our results evidence generalist and opportunistic feeding habits of P. nattereri, one of the most common snake species in Brazil.Asociación Herpetológica Argentin

Cytotoxic prenylated indole alkaloid produced by the endophytic fungus Aspergillus terreus P63

Prenyl indole alkaloids constitute a diverse class of natural products with complex chemical structures and potent biological activities. Investigation of the growth medium EtOAc extract produced by the endophytic fungus Aspergillus terreus P63 collected from roots of the grass Axonopus leptostachyus, yielded the prenylated indole alkaloid, giluterrin, bearing an unprecedented carbon skeleton. The structure of giluterrin was established by analysis of spectroscopic data and HRMS. The absolute configuration of giluterrin was determined by combination of electronic and vibrational circular dichroism analyses. Giluterrin presented antiproliferative profile for prostate (PC-3) and kidney (786-0) cancer cell lines32162167CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQFUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESPsem informação2013/50228-8; 2014/25222-9National Council for Scientific and Technological Development (CNPq)National Council for Scientific and Technological Development (CNPq); National Institute of Science and Technology (INCT BioNat), Brazil [465637/2014-0]; National Institute of Science and Technology (INCT Areas Umidas), Brazil [421733/2017-9]; Sao Paulo State Research Foundation (FAPESP)Fundacao de Amparo a Pesquisa do Estado de Sao Paulo (FAPESP) [2013/50228-8, 2014/25222-9]; Centre for Scientific Computing (NCC/GridUNESP) of Sao Paulo State University (UNESP); FAPESPFundacao de Amparo a Pesquisa do Estado de Sao Paulo (FAPESP

Effect of lung recruitment and titrated Positive End-Expiratory Pressure (PEEP) vs low PEEP on mortality in patients with acute respiratory distress syndrome - A randomized clinical trial

IMPORTANCE: The effects of recruitment maneuvers and positive end-expiratory pressure (PEEP) titration on clinical outcomes in patients with acute respiratory distress syndrome (ARDS) remain uncertain. OBJECTIVE: To determine if lung recruitment associated with PEEP titration according to the best respiratory-system compliance decreases 28-day mortality of patients with moderate to severe ARDS compared with a conventional low-PEEP strategy. DESIGN, SETTING, AND PARTICIPANTS: Multicenter, randomized trial conducted at 120 intensive care units (ICUs) from 9 countries from November 17, 2011, through April 25, 2017, enrolling adults with moderate to severe ARDS. INTERVENTIONS: An experimental strategy with a lung recruitment maneuver and PEEP titration according to the best respiratory-system compliance (n = 501; experimental group) or a control strategy of low PEEP (n = 509). All patients received volume-assist control mode until weaning. MAIN OUTCOMES AND MEASURES: The primary outcome was all-cause mortality until 28 days. Secondary outcomes were length of ICU and hospital stay; ventilator-free days through day 28; pneumothorax requiring drainage within 7 days; barotrauma within 7 days; and ICU, in-hospital, and 6-month mortality. RESULTS: A total of 1010 patients (37.5% female; mean [SD] age, 50.9 [17.4] years) were enrolled and followed up. At 28 days, 277 of 501 patients (55.3%) in the experimental group and 251 of 509 patients (49.3%) in the control group had died (hazard ratio [HR], 1.20; 95% CI, 1.01 to 1.42; P = .041). Compared with the control group, the experimental group strategy increased 6-month mortality (65.3% vs 59.9%; HR, 1.18; 95% CI, 1.01 to 1.38; P = .04), decreased the number of mean ventilator-free days (5.3 vs 6.4; difference, −1.1; 95% CI, −2.1 to −0.1; P = .03), increased the risk of pneumothorax requiring drainage (3.2% vs 1.2%; difference, 2.0%; 95% CI, 0.0% to 4.0%; P = .03), and the risk of barotrauma (5.6% vs 1.6%; difference, 4.0%; 95% CI, 1.5% to 6.5%; P = .001). There were no significant differences in the length of ICU stay, length of hospital stay, ICU mortality, and in-hospital mortality. CONCLUSIONS AND RELEVANCE: In patients with moderate to severe ARDS, a strategy with lung recruitment and titrated PEEP compared with low PEEP increased 28-day all-cause mortality. These findings do not support the routine use of lung recruitment maneuver and PEEP titration in these patients. TRIAL REGISTRATION: clinicaltrials.gov Identifier: NCT01374022