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

Gastroprotective effect of Byrsonima sericea DC leaf extract against ethanol-induced gastric injury and its possible mechanisms of action

Byrsonima sericea leaves are extensively used in folk medicine in Brazil against gastric disorders. This study investigated the chemical constituents of B. sericea leaf ethanolic extract (BSLE) and its potential gastroprotective activity, with its possible mechanism of the action using ethanol to induce gastric mucosal damage in mice. The phytochemical analysis was carried out to identify the active constituents present in the extract, and the HPLC analysis was performed for the identification of flavonoids. BSLE at oral doses of 125, 250 and 500 mg/kg markedly attenuated the ethanol-evoked gastric lesions by 53.2, 84.9 and 87.6 %, respectively. The BSLE (250 mg/kg) prevented the depletion of gastric mucus and gastric mucosal nonproteic-sulfhydryl groups, SOD and CAT, as well as the increase in the MDA content promoted by absolute ethanol. Moreover, the effect of BSLE against ethanol damage was found to be significantly reduced in mice pretreated with Capsazepine (i.p.), L-NAME (i.p.) or glibenclamide (i.p.), the respective blockers/inhibitors of TRPV1, NO synthase and K+ATP channel. The phytochemical investigation on BSLE revealed the presence of flavonoids rutin, isoquercitrin, kaempferol 3-O-rutinoside and quercetin, which are compounds well known for their antioxidant and gastroprotective properties. These results suggest that BSLE affords gastroprotection through multiple mechanisms, which may be helpful in the treatment of pathologies associated with gastric dysfunctions.<br>Folhas de Byrsonima sericea são amplamente utilizadas na medicina popular no Brasil no tratamento de distúrbios gástricos. Este estudo investigou os constituintes químicos do extrato etanólico das folhas de B. sericea (BSLE) e sua atividade gastroprotetora com seus possíveis mecanismos de ação utilizando o modelo de lesão gástrica induzida por etanol em camundongos. A análise fitoquímica foi realizada para identificar os componentes ativos presentes no extrato e análise por HPLC foi realizada para a identificação de flavonóides. A administração de BSLE (v.o.) nas doses de 125, 250, 500 mg/kg, v.o. atenuou significativamente as lesões gástricas induzidas por etanol em 53,2, 84,9 e 87,6% respectivamente. BSLE (250 mg/kg) preveniu a depleção do muco gástrico, de grupamentos sulfidrílicos não-protéicos (GSH), das atividades da SOD e da CAT assim como o aumento de malonaldeído promovido pelo etanol. Além disso, o efeito gastroprotetor do BSLE foi significantemente reduzido pelos pré-tratamentos com capsazepina (i.p.), L-NAME (i.p.) ou glibenclamida (i.p.), respectivamente bloqueadores/inibidores de receptores TRPV1, NO sintase e canais de K+ATP. A investigação fitoquímica revelou a presença de flavonoides como rutina, isoquercitrina, 3-O-rutinosideo-canferol e quercetina que são conhecidas por suas propriedades antioxidantes e gastropotetoras. O estudo demonstrou que BSLE proporciona ação gastroprotetora através de vários mecanismos que podem ser úteis no tratamento de patologias associadas a disfunções gástricas

Proteomics analysis of zebrafish larvae exposed to 3,4-dichloroaniline using the fish embryo acute toxicity test

The zebrafish (Danio rerio) is a small teleost fish that is becoming increasingly popular in laboratories worldwide and several attributes have also placed the zebrafish under the spotlight of (eco)toxicological studies. Since the 1990s, international organizations such as ISO and OECD have published guidelines for the use of zebrafish in ecotoxicological assessment of environmental toxicants such as the Fish Embryo Acute Toxicity (FET) test, OECD n degrees 236 guideline. This protocol uses 3,4-dichloroaniline (DCA), an aniline pesticide whose toxicity to fish species at early life stages is well known, as a positive control. Despite its use, little is known about its molecular mechanisms, especially in the context of the FET test. Therefore, this study aimed to investigate such changes in zebrafish larvae exposed to DCA (4 mg/L) for 96 hours using gel-free proteomics. Twenty-four proteins detected in both groups were identified as significantly affected by DCA exposure, and, when considering group-specific entities, 48 proteins were exclusive to DCA (group-specific proteins) while 248 were only detected in the control group. Proteins modulated by DCA treatment were found to be involved in metabolic processes, especially lipids and hormone metabolism (eg, Apoa1 and Apoa1b and vitelogenins), as well as proteins important for developmental processes and organogenesis (eg, Myhc4, Acta2, Sncb, and Marcksb). The results presented here may therefore provide a better understanding of the relationships between molecular changes and phenotype in zebrafish larvae treated with DCA, the reference compound of the FET test.</p

Galectins in the regulation of platelet biology

Platelets are anucleated blood cells derived from megakaryocytes, and although they are essential for proper hemostasis, their function extends to physiologic processes such as tissue repair, wound remodeling, and antimicrobial host defense, or pathologic conditions such as thrombosis, atherosclerosis, chronic inflammatory diseases, and cancer. Recently, we demonstrated that two structurally divergent members of the galectin family, galectin-1 and galectin-8, are potent platelet agonists. The emergence of galectins as soluble mediators capable of triggering platelet activation opens a new field of research that will provide further insights into the mechanisms linking inflammatory responses to thrombus formation and could expand our view of the role of platelets much beyond hemostasis to their pathophysiologic role during inflammation and cancer. The present article details the various protocols and reagents currently used in our laboratory to study the role of galectins in human platelet function.Fil: Romaniuk, María Albertina. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Medicina Experimental. Academia Nacional de Medicina de Buenos Aires. Instituto de Medicina Experimental; ArgentinaFil: Rabinovich, Gabriel Adrián. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Química Biológica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Biología y Medicina Experimental. Fundación de Instituto de Biología y Medicina Experimental. Instituto de Biología y Medicina Experimental; ArgentinaFil: Schattner, Mirta Ana. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Medicina Experimental. Academia Nacional de Medicina de Buenos Aires. Instituto de Medicina Experimental; Argentin