Netrin-1 promotes naive pluripotency through Neo1 and Unc5b co-regulation of Wnt and MAPK signalling.

In mouse embryonic stem cells (mESCs), chemical blockade of Gsk3α/ß and Mek1/2 (2i) instructs a self-renewing ground state whose endogenous inducers are unknown. Here we show that the axon guidance cue Netrin-1 promotes naive pluripotency by triggering profound signalling, transcriptomic and epigenetic changes in mESCs. Furthermore, we demonstrate that Netrin-1 can substitute for blockade of Gsk3α/ß and Mek1/2 to sustain self-renewal of mESCs in combination with leukaemia inhibitory factor and regulates the formation of the mouse pluripotent blastocyst. Mechanistically, we reveal how Netrin-1 and the balance of its receptors Neo1 and Unc5B co-regulate Wnt and MAPK pathways in both mouse and human ESCs. Netrin-1 induces Fak kinase to inactivate Gsk3α/ß and stabilize ß-catenin while increasing the phosphatase activity of a Ppp2r2c-containing Pp2a complex to reduce Erk1/2 activity. Collectively, this work identifies Netrin-1 as a regulator of pluripotency and reveals that it mediates different effects in mESCs depending on its receptor dosage, opening perspectives for balancing self-renewal and lineage commitment.

Serial genomic inversions induce tissue-specific architectural stripes, gene misexpression and congenital malformations.

Balanced chromosomal rearrangements such as inversions and translocations can cause congenital disease or cancer by inappropriately rewiring promoter-enhancer contacts1,2. To study the potentially pathogenic consequences of balanced chromosomal rearrangements, we generated a series of genomic inversions by placing an active limb enhancer cluster from the Epha4 regulatory domain at different positions within a neighbouring gene-dense region and investigated their effects on gene regulation in vivo in mice. Expression studies and high-throughput chromosome conformation capture from embryonic limb buds showed that the enhancer cluster activated several genes downstream that are located within asymmetric regions of contact, the so-called architectural stripes3. The ectopic activation of genes led to a limb phenotype that could be rescued by deleting the CCCTC-binding factor (CTCF) anchor of the stripe. Architectural stripes appear to be driven by enhancer activity, because they do not form in mouse embryonic stem cells. Furthermore, we show that architectural stripes are a frequent feature of developmental three-dimensional genome architecture often associated with active enhancers. Therefore, balanced chromosomal rearrangements can induce ectopic gene expression and the formation of asymmetric chromatin contact patterns that are dependent on CTCF anchors and enhancer activity.

Focussed assessment of certain existing MRLs of concern for acetamiprid and modification of the existing MRLs for table olives, olives for oil production, barley and oats.

In compliance with Article 43 of Regulation (EC) No 396/2005, EFSA received from the European Commission a mandate to provide its reasoned opinion on the existing maximum residue levels (MRLs) for acetamiprid which might lead to consumers intake concerns on the basis of the new toxicological reference values agreed upon by Member States (MSs) in October 2017. In order to identify the MRLs of potential concern that require a more detailed assessment, EFSA performed a preliminary risk assessment, identifying a risk for consumers for 12 commodities. Measures for reduction of the consumer exposure were assessed by EFSA and should be considered by risk managers. Furthermore, in accordance with Article 6 of Regulation (EC) No 396/2005, ADAMA Makhteshim Ltd submitted two requests to modify the existing MRL for acetamiprid in table olives, olives for oil production, barley and oats. The data submitted in support of the requests were found to be sufficient to derive MRL proposals for all crops under assessment. Based on the risk assessment results, EFSA concluded that the short-term and long-term intake of residues resulting from the use of acetamiprid according to the intended agricultural practices on table olives, olives for oil production, barley and oats is unlikely to present a risk to consumer health.

Extensive Transformation of the Pharmaceutical Carbamazepine Following Uptake into Intact Tomato Plants.

Carbamazepine (CBZ) is an antiepileptic drug which is persistent in wastewater treatment plants and the environment. It has been frequently detected in plant material after irrigation with treated wastewater. To date, little information is, however, available on the transformation of CBZ in plants. In the present study, the uptake, translocation, and transformation of CBZ was studied in hydroponically grown tomato plants. After 35 days of exposure >80% of the total spiked amount of CBZ was taken by the tomato plants and mainly stored in the leaves. A total of 11 transformation products (TP) (mainly phase-I) were quantified by liquid chromatography-tandem mass spectrometry (LC-MS/MS) and their total amount corresponded to 33% of the CBZ taken up. The ratio of CBZ metabolites to CBZ was highest in fruits (up to 2.5) and leaves (0.5), suggesting an intensive transformation of CBZ in these compartments. Further 10 TPs (phase-I and II) were identified by LC-high resolution mass spectrometry screening, likely comprising another 12% of CBZ. On the basis of these experiments and on an experiment with CBZ-10,11-epoxide a transformation pathway of CBZ in intact tomato plants is proposed that involves epoxidation, hydrolysis, hydroxylation, ring contraction, or loss of the carbamoyl group, followed by conjugation to glucose or cysteine, but also reduction of CBZ. This transformation pathway and analytical data of CBZ transformation products allow for their determination also in field grown vegetable and for the generation of more accurate exposure data of consumers of vegetable irrigated with treated municipal wastewater.