Linear stability analysis of morphodynamics during tissue regeneration in plants

One of the key characteristics of multicellular organisms is the ability to establish and maintain shapes, or morphologies, under a variety of physical and chemical perturbations. A quantitative description of the underlying morphological dynamics is a critical step to fully understand the self-organising properties of multicellular systems. Although many powerful mathematical tools have been developed to analyse stochastic dynamics, rarely these are applied to experimental developmental biology. Here, we take root tip regeneration in the plant model system Arabidopsis thaliana as an example of robust morphogenesis in living tissue, and present a novel approach to quantify and model the relaxation of the system to its unperturbed morphology. By generating and analysing time-lapse series of regenerating root tips captured with confocal microscopy, we are able to extract and model the dynamics of key morphological traits at cellular resolution. We present a linear stability analysis of its Markovian dynamics, with the stationary state representing the intact root in the space of morphological traits. This analysis suggests the intriguing co-existence of two distinct temporal scales during the process of root regeneration in Arabidopsis. We discuss the possible biological implications of our specific results, and suggest future experiments to further probe the self-organising properties of living tissue

Vitalism in Early Modern Medical and Philosophical Thought

Vitalism is a notoriously deceptive term. It is very often defined as the view, in biology, in early modern medicine and differently, in early modern philosophy, that living beings differ from the rest of the physical universe due to their possessing an additional ‘life-force’, ‘vital principle’, ‘entelechy’, enormon or élan vital. Such definitions most often have an explicit pejorative dimension: vitalism is a primitive or archaic view, that has somehow survived the emergence of modern science (the latter being defined in many different ways, from demystified Cartesian reductionism to experimental medicine, biochemistry or genetics: Cimino and Duchesneau eds. 1997, Normandin and Wolfe eds. 2013). Such dismissive definitions of vitalism are meant to dispense with argument or analysis. Curiously, the term has gained some popularity in English-language scholarship on early modern philosophy in the past few decades, where it is used without any pejorative dimension, to refer to a kind of ‘active matter’ view, in which matter is not reducible to the (mechanistic) properties of size, shape and motion, possessing instead some internal dynamism or activity (see e.g. James 1999, Boyle 2018, Borcherding forthcoming). The latter meaning is close to what the Cambridge Platonist Ralph Cudworth termed ‘hylozoism’, namely the attribution of life, agency or mind to matter, and he implicitly targeted several figures I shall mention here, notably Margaret Cavendish and Francis Glisson, for holding this view. However, one point I shall make in this entry is that when vitalism first appears by name, and as a self-designation, in the Montpellier School (associated with the Faculty of Medicine at the University of Montpellier, in the second half of the eighteenth century; thus vitalisme appears first, followed shortly thereafter by Vitalismus in German, with ‘vitalism’ appearing in English publications only in the early nineteenth century: Toepfer 2011), it is quite different from both the more ‘supernatural’ view described above – chiefly espoused by its rather obsessive opponents – and from the more neutral, but also de-biologized philosophical view (that of e.g. Cavendish or Conway who are, broadly speaking naturalists). Rather than appealing to a metaphysics of vital force, or of self-organizing matter, this version of vitalism, which I shall refer to as ‘medical vitalism’, seems to be more of a ‘systemic’ theory: an attempt to grasp and describe top-level (‘organizational’, ‘organismic’, ‘holistic’) features of living systems (Wolfe 2017, 2019). In this entry I seek to introduce some periodization in our thinking about early modern (and Enlightenment) vitalism, emphasizing the difference between the seventeenth-century context and that of the following generations – culminating in the ideas of the Montpellier School. This periodization should also function as a kind of taxonomy or at least distinction between some basic types of vitalism. As I discuss in closing, these distinctions can cut across the texts and figures we are dealing with, differently: metaphysical vs. non-metaphysical vitalism, philosophical vs. medical vitalism, medical vs. ‘embryological’ vitalism, and so on. A difference I can only mention but not explore in detail is that the more medically grounded, ‘organismic’ vitalism is significantly post-Cartesian while the more biological/embryological vitalism is, inasmuch as it is a dynamic, self-organizing matter theory, an extension of Renaissance ideas (chymiatry, Galenism and in general theories of medical spirits). I examine successively vitalism’s Renaissance prehistory, its proliferation as ‘vital matter theory’ in seventeenth-century England (in authors such as Cavendish, Conway and Glisson, with brief considerations on Harvey and van Helmont), and its mature expression in eighteenth-century Montpellier (notably with Bordeu and Ménuret de Chambaud)

Chile's export diversification since 1960: A free market miracle or mirage?

Conventional wisdom has proclaimed Chile's recent economic development a 'free market miracle'. In an examination of Chile's export diversification experience, this article departs from that view. By analysing the dynamics underlying the emergence of the salmon, fruit, forestry and wine sectors in Chile's export basket since the 1960s, the study sheds light on the crucial role of industrial policy in the process of capability accumulation that shapes new industries. The article undertakes a qualitative historical analysis of the scope and nature of policy interventions in each of the four sectors and conducts a quantitative policy evaluation using the difference-in-difference method. It finds that public institutions are essential in overcoming market failures inhibiting the emergence of new industries. Specifically, it shows that the government has a key role to play as a catalyst of human capital accumulation, as a venture capitalist, in trade promotion, and in ensuring 'national' sector reputation through a strong regulatory and quality control role. By elaborating on the dynamic process of structural transformation and capability accumulation, this article contributes to theoretical debates on the role of vertical policies in the emergence of new competitive sectors, and debates relating to static versus dynamic approaches to comparative advantage

Investigating trophic ecology and dietary niche overlap among morphs of Lake Trout in Lake Superior

Four morphs of Lake Trout (Salvelinus namaycush, Walbaum 1792) have been identified in Lake Superior: leans, siscowets, humpers, and redfins. In this comprehensive study, the trophic ecology of Lake Trout morphs were characterized using stomach content, fatty acid, and stable isotope data. Stomach content results indicated a predominately piscivorous diet for leans, siscowets, and redfins, whereas humper diets were comprised of 50% fish and 50% Mysis by mass. Humper and siscowets were most similar in their dietary fatty acid profiles, whereas redfins had the most distinct dietary fatty acid profile. Results from stable isotope analysis revealed some among-morph differences along a pelagic-profundal consumption gradient (34S), but there were no significant differences in trophic position (15N) or basal carbon sources among morphs (13C). Using the recently developed nicheROVER software package, 4-dimensional trophic niches for each morph were quantified using stable isotope ratios (δ13C, δ15N, and δ34S) and fatty acid profiles (30 dietary fatty acids, condensed to one axis). Humpers had the largest 4-dimensional niche regions of all four morphs, and redfins had the smallest. Pairwise probability of overlap among morphs in these four-dimensional niche regions was determined to be < 50% in most cases. Overall, stomach content results indicate that humpers diets were more planktivorous than the other morphs, consistent with previous research. Results of the niche overlap analysis suggests some degree of generalist feeding for all morphs. Better characterization of seasonal variation in diet using tracers that reflect more recent feeding (e.g., fatty acids, stomach contents, and/or stable isotope analyses performed on tissues that turnover more quickly than muscle) are needed to further elucidate among-morph differences and similarities in diet and trophic ecology

Influence of freezing skin grapes to extract phenolic compounds during red wine maceration

Wine quality depends on phenolic and aromatic compounds that are mainly located in skins and seeds of grapes and can be better extracted if suitable extraction technologies are applied. An increase in extractability has impact in the mouth feel, color and age ability of the wines. Using liquid or solid CO2 is a way to promote the breakdown of the cells membranes and enhance extraction of these compounds and protecting grapes and wine from oxidation. The main goal was to test the impact of solid CO2 addition to destemmed grapes with a new CO2 dispenser equipment in order to freeze the berry skins and improve the phenolic extraction in an economic and sustainable way in cv. Cabernet Sauvignon and Pinot Noir. The experiment designed for both cultivars was a treatment with CO2 addition and a control without CO2 addition each one with three replicates. Destemmed grapes submitted to carbonic snow reached temperature of the skins between − 1 and − 4 °C during four minutes under equipment treatment. The consumption of carbon dioxide was estimated around 0.3(kg ⋅kg−1)CO2 per berries. Wines of Cabernet Sauvignon and Pinot noir from fresh grapes and frozen grapes were made and were being compared in phenolic composition and sensory attributes

Genetic diversity and pedigree for Sophora toromiro (Leguminosae): A tree extinct in the wild

Sophora toromiro was endemic to the Pacific island of Papa Nui (Easter Island) and is extinct in the wild. The species has survived in private and botanic gardens. The species is the subject of an international study to support its conservation ex situ and eventual reintroduction. As a contribution to this study the genetic diversity of the surviving stocks and herbarium samples has been assessed by means of random amplified polymorphic DNA (RAPD) and inter-simple sequence repeat (inter-SSR) analysis. The analysis indicated low levels of genetic diversity suggesting a very small number of founders. In addition, misidentified trees were identified allowing their removal from the conservation project