Patterning and growth are fundamental features of embryonic development that must be tightly coordinated. To understand how metabolism impacts early mesoderm development, we used mouse embryonic ...stem-cell-derived gastruloids, that co-expressed glucose transporters with the mesodermal marker T/Bra. We found that the glucose mimic, 2-deoxy-D-glucose (2-DG), blocked T/Bra expression and abolished axial elongation in gastruloids. However, glucose removal did not phenocopy 2-DG treatment despite a decline in glycolytic intermediates. As 2-DG can also act as a competitive inhibitor of mannose in protein glycosylation, we added mannose together with 2-DG and found that it could rescue the mesoderm specification both in vivo and in vitro. We further showed that blocking production and intracellular recycling of mannose abrogated mesoderm specification. Proteomics analysis demonstrated that mannose reversed glycosylation of the Wnt pathway regulator, secreted frizzled receptor Frzb. Our study showed how mannose controls mesoderm specification in mouse gastruloids.
Display omitted
•2-Deoxy-D-Glucose affects mesoderm specification through mannose inhibition•De novo and salvage mannose synthesis pathways control mesoderm specification•Mannose controls mesoderm specification in gastruloids and gastrulating embryos•Mannose-dependent protein glycosylation is required for mesoderm specification
Dingare et al. identified a critical role for mannose-dependent glycosylation during early mesoderm specification both in mouse embryonic stem-cell-derived gastruloids and in gastrulating mouse embryos. Blocking intracellular mannose production and its usage in glycosylation inhibited mesoderm specification and symmetry breaking in gastruloids.
In a rapidly changing world, quantifying ecosystem resilience is an important challenge. Historically, resilience has been defined via models that do not take spatial effects into account. These ...systems can only adapt via uniform adjustments. In reality, however, the response is not necessarily uniform, and can lead to the formation of (self‐organised) spatial patterns – typically localised vegetation patches. Classical measures of resilience cannot capture the emerging dynamics in spatially self‐organised systems, including transitions between patterned states that have limited impact on ecosystem structure and productivity. We present a framework of interlinked phase portraits that appropriately quantifies the resilience of patterned states, which depends on the number of patches, the distances between them and environmental conditions. We show how classical resilience concepts fail to distinguish between small and large pattern transitions, and find that the variance in interpatch distances provides a suitable indicator for the type of imminent transition. Subsequently, we describe the dependency of ecosystem degradation based on the rate of climatic change: slow change leads to sporadic, large transitions, whereas fast change causes a rapid sequence of smaller transitions. Finally, we discuss how pre‐emptive removal of patches can minimise productivity losses during pattern transitions, constituting a viable conservation strategy.
Classical measures of resilience cannot capture the emerging dynamics in spatially self‐organized, patterned systems, including transitions between patterned states that have limited impact on ecosystem structure and productivity. To complement these classical concepts, we present a framework of interlinked phase portraits that appropriately quantifies the resilience of patterned states, which depends on the number of patches, the distances between them and environmental conditions.
Life as we know it would not exist without water. However, water molecules not only serve as a solvent and reactant but can also promote hydrolysis, which counteracts the formation of essential ...organic molecules. This conundrum constitutes one of the central issues in origin of life. Hydrolysis is an important part of energy metabolism for all living organisms but only because, inside cells, it is a controlled reaction. How could hydrolysis have been regulated under prebiotic settings? Lower water activities possibly provide an answer: geochemical sites with less free and more bound water can supply the necessary conditions for protometabolic reactions. Such conditions occur in serpentinising systems, hydrothermal sites that synthesise hydrogen gas via rock–water interactions. Here, we summarise the parallels between biotic and abiotic means of controlling hydrolysis in order to narrow the gap between biochemical and geochemical reactions and briefly outline how hydrolysis could even have played a constructive role at the origin of molecular self‐organisation.
Porous and highly ordered: After metal–organic frameworks (MOFs), which were first described over ten years ago, a new class of porous materials has been introduced: covalent organic frameworks ...(COFs), which are distinguished by high thermostabilities, large specific surface areas, and low densities. The example shows a model structure of COF‐108.
This paper provides a concise description of the free energy principle, starting from a formulation of random dynamical systems in terms of a Langevin equation and ending with a Bayesian mechanics ...that can be read as a physics of sentience. It rehearses the key steps using standard results from statistical physics. These steps entail (i) establishing a particular partition of states based upon conditional independencies that inherit from sparsely coupled dynamics, (ii) unpacking the implications of this partition in terms of Bayesian inference and (iii) describing the paths of particular states with a variational principle of least action. Teleologically, the free energy principle offers a normative account of self-organisation in terms of optimal Bayesian design and decision-making, in the sense of maximising marginal likelihood or Bayesian model evidence. In summary, starting from a description of the world in terms of random dynamical systems, we end up with a description of self-organisation as sentient behaviour that can be interpreted as self-evidencing; namely, self-assembly, autopoiesis or active inference.
Display omitted
•This paper provides a concise derivation of the free energy principle.•The FEP is a normative account of self-organisation and sentient behaviour:•It describes self-organisation as maximizing Bayesian model evidence,•And sentient behaviour as optimal Bayesian design and decision-making.•Altogether, we start from a description of the world as a random dynamical system,•And end with a Bayesian mechanics that can be read as a physics of sentience.
Snails are highly unusual among multicellular animals in that they move on a layer of costly mucus, leaving behind a trail that can be followed and utilized for various purposes by themselves or by ...other animals. Here we review more than 40 years of experimental and theoretical research to try to understand the ecological and evolutionary rationales for trail‐following in gastropods. Data from over 30 genera are currently available, representing a broad taxonomic range living in both aquatic and terrestrial environments. The emerging picture is that the production of mucus trails, which initially was an adaptation to facilitate locomotion and/or habitat extension, has evolved to facilitate a multitude of additional functions. Trail‐following supports homing behaviours, and provides simple mechanisms for self‐organisation in groups of snails, promoting aggregation and thus relieving desiccation and predation pressures. In gastropods that copulate, trail‐following is an important component in mate‐searching, either as an alternative, or in addition to the release of water‐ or air‐borne pheromones. In some species, this includes a capacity of males not only to identify trails of conspecifics but also to discriminate between trails laid by females and males. Notably, trail discrimination seems important as a pre‐zygotic barrier to mating in some snail species. As production of a mucus trail is the most costly component of snail locomotion, it is also tempting to speculate that evolution has given rise to various ways to compensate for energy losses. Some snails, for example, increase energy intake by eating particles attached to the mucus of trails that they follow, whereas others save energy through reducing the production of their own mucus by moving over previously laid mucus trails. Trail‐following to locate a prey item or a mate is also a way to save energy. While the rationale for trail‐following in many cases appears clear, the basic mechanisms of trail discrimination, including the mechanisms by which many snails determine the polarity of the trail, are yet to be experimentally determined. Given the multiple functions of trail‐following we propose that future studies should adopt an integrated approach, taking into account the possibility of the simultaneous occurrence of many selectively advantageous roles of trail‐following behaviour in gastropods. We also believe that future opportunities to link phenotypic and genotypic traits will make possible a new generation of research projects in which gastropod trail‐following, its multitude of functions and evolutionary trade‐offs can be further elucidated.
•Microentrepreneurs in rural China devise self–serving entrepreneurship clusters to tackle resource scarcity.•Their weak institutional contexts induce a mindset of conformity with culture, norms, and ...business ideologies.•Their self–serving clusters are based on self–organised small–scale acts of reciprocity, solidarity, and camaraderie.•Entrepreneurship policies for social change are needed to build economically and socially equal Chinese neighbourhoods.
Research overemphasises the facilitative role of institutions in cluster formation. It overlooks the collective actions by microentrepreneurs when confronting issues of microentrepreneurship in a weak institutional environment. Drawing from a social embeddedness perspective in entrepreneurship, we analyse the mechanisms underlying their methods of self-organisation for collective action, particularly in cluster formation. Interviews involving 19 microentrepreneurs in rural China revealed that they self-organised to form self-serving clusters by engaging in small-scale entrepreneurial acts of reciprocal and cooperative behaviours, solidarity, camaraderie, and by adopting Chinese business ideologies. Such an understanding contributes to research on clusters, as it reveals ways in which microentrepreneurs in a weak institutional environment leverage localised economic, social, and cultural forces to collectively form self-serving clusters. This foregrounds the role of microentrepreneurs in establishing a socioeconomic equilibrium in such an environment and it holds social, academic, and policy implications.
PDF
