Distortion of Competition and Effect on Trade Between Member States

peer reviewe

Proto-Planetary Disk Chemistry Recorded by D-Rich Organic Radicals in Carbonaceous Chondrites

Insoluble organic matter (IOM) in primitive carbonaceous meteorites has preserved its chemical composition and isotopic heterogeneity since the solar system formed ~4.567 billion years ago. We have identified the carrier moieties of isotopically anomalous hydrogen in IOM isolated from the Orgueil carbonaceous chondrite. Data from high spatial resolution, quantitative isotopic NanoSIMS mapping of Orgueil IOM combined with data from electron paramagnetic resonance spectroscopy reveals that organic radicals hold all the deuterium excess (relative to the bulk IOM) in distinct, micrometer-sized, D-rich hotspots. Taken together with previous work, the results indicate that an isotopic exchange reaction took place between pre-existing organic compounds characterized by low D/H ratios and D-rich gaseous molecules, such as H_2D^+ or HD_2^+. This exchange reaction most likely took place in the diffuse outer regions of the proto-planetary disk around the young Sun, offering a model that reconciles meteoritic and cometary isotopic compositions of organic molecules

Impact of climate change on the ecology of the Kyambangunguru crater marsh in southwestern Tanzania during the Late Holocene

Instrumental records of temperature and hydrological regimes in East Africa evidence frequent droughts with dramatic effects on population and ecosystems. Sources of these climatic variations remain largely unconstrained, partly because of a paucity of Late Holocene records. Here, we present a multi-proxy analysis of a 4-m continuous sediment core collected in the Kyambangunguru crater marsh, in southwest Tanzania, covering the last 4000 yrs (cal. BP). We used microscopic (macro-remains, microfossils, palynofacies, pollen), elemental (carbon, nitrogen contents), molecular (br GDGTs, n-alkanes) and compound-specific isotopic (δ2H n-alkanes) investigations to reconstruct the environmental history of the marsh. The multi proxy record reveals that, 2500 years ago, the marsh underwent a major ecological transition from a lake to a peatland. Temperature and hydrological reconstructions evidence warmer and drier conditions between 2200 and 860 cal. BP, which probably triggered the establishment of a perennial peatland. This study is one of the first combined temperature and precipitation record of Late Holocene in the region and highlights changes in the spatial distribution of the East African climate regimes. Several cold periods are observed, between 3300 and 2000 cal. BP and since 630 cal. BP, the latter corresponding to the Little Ice Age. Moreover, wetter conditions are reported during the Medieval Climate Anomaly in contrast to other north-eastern African records suggesting that Tanzania is located at the transition between two hydro-climatic zones (north-eastern versus southern Africa) and has experienced variable contributions of these two zones over the last millennium

Earthworm Cast Formation and Development: A Shift From Plant Litter to Mineral Associated Organic Matter

Earthworms play a major role in litter decomposition, in processing soil organic matter and driving soil structure formation. Earthworm casts represent hot spots for carbon turnover and formation of biogeochemical interfaces in soils. Due to the complex microscale architecture of casts, understanding the mechanisms of cast formation and development at a process relevant scale, i.e., within microaggregates and at the interface between plant residues, microorganisms and mineral particles, remains challenging. We used stable isotope enrichment to trace the fate of shoot and root litter in intact earthworm cast samples. Surface casts produced by epi-anecic earthworms (Lumbricus terrestris) were collected after 8 and 54 weeks of soil incubation in mesocosms, in the presence of 13C-labeled Ryegrass shoot or root litter deposited onto the soil surface. To study the alteration in the chemical composition from initial litter to particulate organic matter (POM) and mineral-associated organic matter (MOM) in cast samples, we used solid-state 13C Nuclear Magnetic Resonance spectroscopy (13C-CPMAS-NMR) and isotopic ratio mass spectrometry (EA-IRMS). We used spectromicroscopic approach to identify plant tissues and microorganisms involved in plant decomposition within casts. A combination of transmission electron microscopy (TEM) and nano-scale secondary ion mass spectrometry (NanoSIMS) was used to obtain the distribution of organic carbon and δ13C within intact cast sample structures. We clearly demonstrate a different fate of shoot- and root-derived organic carbon in earthworm casts, with a higher abundance of less degraded root residues recovered as particulate organic matter on the short-term (8 weeks) (73 mg·g−1 in Cast-Root vs. 44 mg·g−1 in Cast-Shoot). At the early stages of litter decomposition, the chemical composition of the initial litter was the main factor controlling the composition and distribution of soil organic matter within casts. At later stages, we can demonstrate a clear reduction of structural and chemical differences in root and shoot-derived organic products. After 1 year, MOM clearly dominated the casts (more than 85% of the total OC in the MOM fraction). We were able to highlight the shift from a system dominated by free plant residues to a system dominated by MOM during cast formation and development

Selection of peptides for a muscle-targeted delivery of ASOs directed against DUX4 mRNAs through complementary approaches in silico, in vitro and in vivo.

editorial reviewedIn a therapeutic goal for FSHD, antisense oligonucleotides (ASOs) directed against DUX4 mRNAs have been developed at UMONS. However, ASO use is limited by their restricted tissue delivery, lack of tissue selectivity, and rapid clearance. By screening a phage-display library of linear peptides against #1 myotubes or #2 a muscle-membrane protein (MMP), we selected peptides (MSPep) that specifically bind to muscle surface proteins. The 4 most promising MSPeps were synthesized with Rhodamine conjugation and added to cell culture media to study their internalization into myotubes (UBic, 54-6), hepatocytes (HepaRG, HepG2) or renal cells (HEK293). At all tested doses (10, 40 µM), MSPepIC (from screening #1) and MSPep1-3 (from screening #2) were internalized into myotubes after 2h of incubation. As expected, MSPepIC and MSPep1-3 were not internalized by renal cells that do not express endogenous MMP. MSPep 1-3 were only internalized by renal cells when they were transfected with a MMP expression plasmid. MSPepIC was internalized by hepatocytes but to a lesser extent as compared to myotubes. MSPep1 is internalized hepatocytes at a bigger extent than MSPepIC and MSPep 2-3, likely due to its helical tertiary structure. MSPep-ASO complexes were designed in silico based on literature data and collaborators’ expertise. The next experiments will evaluate the ability of MSPep-ASOs to target skeletal muscle and deliver ASO efficiently into muscle cells

Selection of peptides for a muscle-targeted delivery of ASOs directed against DUX4 mRNAs through complementary approaches in silico, in vitro and in vivo.

editorial reviewedFacioscapulohumeral dystrophy (FSHD) is a hereditary myopathy caused by the aberrant expression in skeletal muscle of the DUX4 protein that is normally only expressed in early embryogenesis. Antisense oligonucleotides (ASOs) directed against DUX4 mRNAs have been developed as a therapeutic approach. However, ASO use is limited by their restricted tissue delivery, lack of tissue selectivity, and rapid clearance. By screening a phage-display library of linear peptides against #1 myotubes or #2 a muscle-membrane protein (MMP), we selected peptides (MSPep) that specifically bind to muscle surface proteins. The 4 most promising MSPeps were synthesized with Rhodamine conjugation and added to cell culture media to study their internalization into myotubes (5 days of differentiation), hepatocytes (HepaRG, HepG2) or renal cells (HEK293). At all tested doses (10, 40 µM), MSPepIC (from screening #1) and MSPep1-3 (from screening #2) were internalized into myotubes after 2h of incubation. As expected, MSPepIC and MSPep1-3 were not internalized by renal cells that do not express endogenous MMP. MSPep 1-3 were only internalized by renal cell when they were transfected with a MMP expression plasmid. MSPepIC was internalized by hepatocytes but to a lesser extend as compared to myotubes. MSpep 1, 2 or 3 will be selected for ASO conjugation according to results obtained on hepatocytes (ongoing experiments). We designed MSPep-ASO complexes in silico based on literature data and collaborators’ expertise. Concerning ASO selection, the pLAM PolyA (-13+6) sequence (designed to affect DUX4 mRNA polyadenylation) and the pLAM3A (-12+13) sequence (targeting a splice site in DUX4 mRNA 3′UTR) were chosen for their known efficiency to counteract DUX4 expression in cell culture in vitro and in murine models. The 2’-methoxyethyl (2’MOE) PS chemistry will be used for ASO conjugation to MSPeps through a thiol-maleimide linker. Short polyethylene glycol segments will be added to the structure as well as a FAM fluorochrome. On-going experiments aim to evaluate the ability of MSPep-ASOs to target skeletal muscle and deliver ASO efficiently into muscle cells

Evaluation of branched GDGTs and leaf wax n-alkane δ2H as (paleo) environmental proxies in East Africa

The role of mountain evolution on local climate is poorly understood and potentially underestimated in climate models. One prominent example is East Africa, which underwent major geodynamic changes with the onset of the East African Rift System (EARS) more than 250 Myr ago. This study explores, at the regional East African scale, a molecular approach for terrestrially-based paleo-climatic reconstructions that takes into account both changes in temperature and in altitude, potentially leading to an improved concept in paleo-climatic reconstructions. Using surface soils collected along pronounced altitudinal gradients in Mt. Rungwe (n=40; Southwest Tanzania) and Mt. Kenya (n=20; Central Kenya), we investigate the combination of 2 terrestrial proxies, leaf wax n-alkane δ2H (δ2Hwax) and branched glycerol dialkyl glycerol tetraether (br GDGT) membrane lipids, as (paleo) elevation and (paleo) temperature proxies, respectively. At the mountain scale, a weak link between δ2Hwax and altitude (R2 = 0.33) is observed at Mt. Kenya, but no relationship is observed at Mt. Rungwe. It is likely that additional parameters, such as decreasing relative humidity (RH) or vegetation changes with altitude, are outcompeting the expected 2H-depletion trend along Mt. Rungwe. In contrast, br GDGT-derived absolute mean annual air temperature (MAAT) and temperature lapse rate (0.65 °C/100 m) for both mountains are in good agreement with direct field measurements, further supporting the robustness of this molecular proxy for (paleo) temperature reconstructions. At the regional scale, estimated and observed δ2H data in precipitation along 3 mountains in East Africa (Mts. Rungwe, Kenya and Kilimanjaro) highlight a strong spatial heterogeneity, preventing the establishment of a regional based calibration of δ2Hwax for paeloaltitudinal reconstructions. Different from that, an improved regional soil calibration is developed between br GDGT distribution and MAAT by combining the data from this study (Mts. Rungwe and Kenya) with previous results from East African surface soils along Mts. Kilimanjaro (Tanzania) and Rwenzori (Uganda). This new regional calibration, based on 105 samples, improves both the R2 (0.77) and RMSE (root mean square error; 2.4 °C) of br GDGT-derived MAAT over the global soil calibrations previously established (R2 = 0.56; RMSE = 4.2 °C) and leads to more accurate (paleo) temperature reconstructions in the region

Incorporation of 13C labelled shoot residues in Lumbricus terrestris casts: A combination of transmission electron microscopy and nanoscale secondary ion mass spectrometry

Earthworms transform organo-mineral associations in soil, especially by incorporating fresh residuesinside casts where the microbial abundance and activity are enhanced. The heterogeneous distribution oforganic carbon in these structures influences decomposition levels at the microscale. The incorporationof 13C labelled plant residues by Lumbricus terrestris inside cast was investigated, through the innovativecombination of two fine scale imaging techniques: transmission electron microscopy and nanoscalesecondary ion mass spectrometry (NanoSIMS). The association of these methods sheds new lights onorgano-mineral structures. Different types of organic matter (plant residues, microbial remains) wereidentified in the casts and the freshly incorporated residues could be differentiated from the indigenousorganic matter thanks to d13C NanoSIMS mapping. 13C labelled bacteria and fungi abundance and diversityhighlight their preeminent role in litter decomposition within casts. Labelled plant residuesobserved at various stages of decomposition and microorganisms presented highly variable d13C values,emphasizing the complexity of organic matter dynamics and the importance of microscale analyses todescribe this variability. Thus, the combination of NanoSIMS and TEM shows great potential to relateorganic matter stages of decomposition with their 13C signature