Fluvial carbon export from a lowland Amazonian rainforest in relation to atmospheric fluxes

We constructed a whole carbon budget for a catchment in the Western Amazon Basin, combining drainage water analyses with eddy covariance measured terrestrial CO2 fluxes. As fluvial C export can represent permanent C export it must be included in assessments of whole site C balance, but is rarely done. The footprint area of the flux tower is drained by two small streams (~5-7 km2) from which we measured the dissolved inorganic carbon (DIC), dissolved organic carbon (DOC), particulate organic carbon (POC) export and CO2 efflux. The EC measurements showed the site C balance to be +0.7 ± 9.7 Mg C ha-1 yr-1 (a source to the atmosphere) and fluvial export was 0.3 ± 0.04 Mg C ha-1 yr-1. Of the total fluvial loss 34% was DIC, 37% DOC and 29% POC. The wet season was most important for fluvial C export. There was a large uncertainty associated with the EC results and with previous biomass plot studies (-0.5 ± 4.1 Mg C ha-1 yr-1), hence it cannot be concluded with certainty whether the site is C sink or source. The fluvial export corresponds to only 3-7 % of the uncertainty related to the site C balance, thus other factors need to be considered to reduce the uncertainty and refine the estimated C balance. However, stream C export is significant, especially for almost neutral sites where fluvial loss may determine the direction of the site C balance. The fate of C downstream then dictates the overall climate impact of fluvial export

Pdx1 is transcriptionally regulated by EGR-1 during nitric oxide-induced endoderm differentiation of mouse embryonic stem cells

The transcription factor, early growth response-1 (EGR-1), is involved in the regulation of cell differentiation, proliferation, and apoptosis in response to different stimuli. EGR-1 is described to be involved in pancreatic endoderm differentiation, but the regulatory mechanisms controlling its action are not fully elucidated. Our previous investigation reported that exposure of mouse embryonic stem cells (mESCs) to the chemical nitric oxide (NO) donor diethylenetriamine nitric oxide adduct (DETA-NO) induces the expression of early differentiation genes such as pancreatic and duodenal homeobox 1 (Pdx1). We have also evidenced that Pdx1 expression is associated with the release of polycomb repressive complex 2 (PRC2) and P300 from the Pdx1 promoter; these events were accompanied by epigenetic changes to histones and site-specific changes in the DNA methylation. Here, we investigate the role of EGR-1 on Pdx1 regulation in mESCs. This study reveals that EGR-1 plays a negative role in Pdx1 expression and shows that the binding capacity of EGR-1 to the Pdx1 promoter depends on the methylation level of its DNA binding site and its acetylation state. These results suggest that targeting EGR-1 at early differentiation stages might be relevant for directing pluripotent cells into Pdx1-dependent cell lineages.C.S.-A. was a doctoral PFIS fellow of ISCIII (FI11/00301). This study was supported by grants from Consejería de Igualdad, Salud y Políticas Sociales, Junta de Andalucía (PI105/2010, TCMR06/009, and PI-0022) to F.J.B. and F.M.; from Consejería de Economía, Innovación, Ciencia y Empleo, Junta de Andalucía (CTS-7127/2011) to F.J.B.; from ISCIII cofunded by Fondos FEDER (RED-TERCEL RD 16-011-0034, along with PICI PICI21/00016 and GVA-COVID19/2021/047 to B.S.); from Servicio Andaluz de Salud (SAS 11245), and from Ministerio de Economía y Competitividad- Secretaría de Estado de Investigación Desarrollo e Innovación (IPT-2011-1615-900000). Along with this, there was support to PAIDI group CTS576, and by the European Regional Development Fund (FEDER) and the Consejería de Economía, Conocimiento, Empresas y Universidades de la Junta de Andalucía, within the framework of the operational program FEDER Andalucía 2014–2020. Specific Objective 1.2.3 “Promotion and generation of frontier knowledge and knowledge oriented to the challenges of society, development of emerging technologies” led the reference research project (UPO-1381598) of J.R.T.Peer reviewe