118 research outputs found
Indexing the Pseudomonas specialized metabolome enabled the discovery of poaeamide B and the bananamides
Pseudomonads are cosmopolitan microorganisms able to produce a wide array of specialized metabolites. These molecules allow Pseudomonas to scavenge nutrients, sense population density and enhance or inhibit growth of competing microorganisms. However, these valuable metabolites are typically characterized one-molecule–one-microbe at a time, instead of being inventoried in large numbers. To index and map the diversity of molecules detected from these organisms, 260 strains of ecologically diverse origins were subjected to mass-spectrometry-based molecular networking. Molecular networking not only enables dereplication of molecules, but also sheds light on their structural relationships. Moreover, it accelerates the discovery of new molecules. Here, by indexing the Pseudomonas specialized metabolome, we report the molecular-networking-based discovery of four molecules and their evolutionary relationships: a poaeamide analogue and a molecular subfamily of cyclic lipopeptides, bananamides 1, 2 and 3. Analysis of their biosynthetic gene cluster shows that it constitutes a distinct evolutionary branch of the Pseudomonas cyclic lipopeptides. Through analysis of an additional 370 extracts of wheat-associated Pseudomonas, we demonstrate how the detailed knowledge from our reference index can be efficiently propagated to annotate complex metabolomic data from other studies, akin to the way in which newly generated genomic information can be compared to data from public databases
Culture of Mouse Embryonic Stem Cells with Serum but without Exogenous Growth Factors Is Sufficient to Generate Functional Hepatocyte-Like Cells
Mouse embryonic stem cells (mESC) have been used to study lineage specification in vitro, including towards a hepatocyte-like fate, and such investigations guided lineage differentiation protocols for human (h)ESC. We recently described a four-step protocol to induce hepatocyte-like cells from hESC which also induced hepatocyte-like cell differentiation of mouse induced pluripotent stem cells. As ESC also spontaneously generate hepatocyte-like cells, we here tested whether the growth factors and serum used in this protocol are required to commit mESC and hESC to hepatocyte-like cells. Culture of mESC from two different mouse strains in the absence of serum and growth factors did not induce primitive streak/definitive endoderm genes but induced default differentiation to neuroectoderm on day 6. Although Activin-A and Wnt3 induced primitive streak/definitive endoderm transcripts most robustly in mESC, simple addition of serum also induced these transcripts. Expression of hepatoblast genes occurred earlier when growth factors were used for mESC differentiation. However, further maturation towards functional hepatocyte-like cells was similar in mESC progeny from cultures with serum, irrespective of the addition of growth factors, and irrespective of the mouse strain. This is in contrast to hESC, where growth factors are required for specification towards functional hepatocyte-like cells. Culture of mESC with serum but without growth factors did not induce preferential differentiation towards primitive endoderm or neuroectoderm. Thus, although induction of primitive streak/definitive endoderm specific genes and proteins is more robust when mESC are exposed to a combination of serum and exogenous growth factors, ultimate generation of hepatocyte-like cells from mESC occurs equally well in the presence or absence of exogenous growth factors. The latter is in contrast to what we observed for hESC. These results suggest that differences exist between lineage specific differentiation potential of mESC and hESC, requiring optimization of different protocols for ESC from either species
Recommended from our members
INSPIRE: A European training network to foster research and training in cardiovascular safety pharmacology
Safety pharmacology is an essential part of drug development aiming to identify, evaluate and investigate undesirable pharmacodynamic properties of a drug primarily prior to clinical trials. In particular, cardiovascular adverse drug reactions (ADR) have halted many drug development programs. Safety pharmacology has successfully implemented a screening strategy to detect cardiovascular liabilities, but there is room for further refinement. In this setting, we present the INSPIRE project, a European Training Network in safety pharmacology for Early Stage Researchers (ESRs), funded by the European Commission's H2020-MSCA-ITN programme. INSPIRE has recruited 15 ESR fellows that will conduct an individual PhD-research project for a period of 36 months. INSPIRE aims to be complementary to ongoing research initiatives. With this as a goal, an inventory of collaborative research initiatives in safety pharmacology was created and the ESR projects have been designed to be complementary to this roadmap. Overall, INSPIRE aims to improve cardiovascular safety evaluation, either by investigating technological innovations or by adding mechanistic insight in emerging safety concerns, as observed in the field of cardio-oncology. Finally, in addition to its hands-on research pillar, INSPIRE will organize a number of summer schools and workshops that will be open to the wider community as well. In summary, INSPIRE aims to foster both research and training in safety pharmacology and hopes to inspire the future generation of safety scientists
The Future of International Investment Regulation: Towards a World Investment Organisation?
With growth in foreign investment and in the number of companies investing in foreign countries, the application of general principles of public international law has not been deemed adequate to regulate foreign investment and there is, as yet, no comprehensive international treaty on the regulation of foreign investment. Consequently, states have resorted to bilateral investment treaties (BITs), regional trade and international investment agreements (IIAs) and free trade agreements (FTAs) to supplement and complement the regime of protection for foreign investors. In the absence of an international investment court, states hosting foreign investment or investor states have opted for investor-state dispute settlement mechanism (ISDS). This mechanism has brought about its own challenges to the international law of foreign investment due to inconsistency in the application and interpretation of the key principles of international investment law by such arbitration tribunals, and further, there is no appellate mechanism to bring about some cohesion and consistency in jurisprudence. Therefore, there are various proposals mooted by scholars to address these challenges and they range from tweaks to BITs and IIAs, the creation of an appellate mechanism and the negotiation of a multilateral treaty to proposals for reform of ISDS only. After assessing the merits and demerits of such proposals, this study goes further, arguing for the creation of a World Investment Organisation (WIO) with a standing mechanism for settlement of investment disputes in order to ensure legal certainty, predictability and the promotion of the flow of foreign investment in a sustainable and responsible manner
The global governance of human cloning: the case of UNESCO
Since Dolly the Sheep was cloned in 1996, the question of whether human reproductive cloning should be banned or pursued has been the subject of international debate. Feelings run strong on both sides. In 2005, the United Nations adopted its Declaration on Human Cloning to try to deal with the issue. The declaration is ambiguously worded, prohibiting “all forms of human cloning inasmuch as they are incompatible with human dignity and the protection of human life”. It received only ambivalent support from UN member states. Given this unsatisfactory outcome, in 2008 UNESCO (the United Nations Educational, Scientific and Cultural Organization) set up a Working Group to investigate the possibility of a legally binding convention to ban human reproductive cloning. The Working Group was made up of members of the International Bioethics Committee, established in 1993 as part of UNESCO’s Bioethics Programme. It found that the lack of clarity in international law is unhelpful for those states yet to formulate national regulations or policies on human cloning. Despite this, member states of UNESCO resisted the idea of a convention for several years. This changed in 2015, but there has been no practical progress on the issue. Drawing on official records and first-hand observations at bioethics meetings, this article examines the human cloning debate at UNESCO from 2008 onwards, thus building on and advancing current scholarship by applying recent ideas on global governance to an empirical case. It concludes that, although human reproductive cloning is a challenging subject, establishing a robust global governance framework in this area may be possible via an alternative deliberative format, based on knowledge sharing and feasibility testing rather than the interest-based bargaining that is common to intergovernmental organizations and involving a wide range of stakeholders. This article is published as part of a collection on global governance
Human Embryonic and Rat Adult Stem Cells with Primitive Endoderm-Like Phenotype Can Be Fated to Definitive Endoderm, and Finally Hepatocyte-Like Cells
Stem cell-derived hepatocytes may be an alternative cell source to treat liver diseases or to be used for pharmacological purposes. We developed a protocol that mimics mammalian liver development, to differentiate cells with pluripotent characteristics to hepatocyte-like cells. The protocol supports the stepwise differentiation of human embryonic stem cells (ESC) to cells with characteristics of primitive streak (PS)/mesendoderm (ME)/definitive endoderm (DE), hepatoblasts, and finally cells with phenotypic and functional characteristics of hepatocytes. Remarkably, the same protocol can also differentiate rat multipotent adult progenitor cells (rMAPCs) to hepatocyte-like cells, even though rMAPC are isolated clonally from cultured rat bone marrow (BM) and have characteristics of primitive endoderm cells. A fraction of rMAPCs can be fated to cells expressing genes consistent with a PS/ME/DE phenotype, preceding the acquisition of phenotypic and functional characteristics of hepatocytes. Although the hepatocyte-like progeny derived from both cell types is mixed, between 10–20% of cells are developmentally consistent with late fetal hepatocytes that have attained synthetic, storage and detoxifying functions near those of adult hepatocytes. This differentiation protocol will be useful for generating hepatocyte-like cells from rodent and human stem cells, and to gain insight into the early stages of liver development
- …