Welfare-Enhancing Collusion in the Presence of a Competitive Fringe

Following the structure of many commodity markets, we consider a few large firms and a competitive fringe of many small suppliers choosing quantities in an infinite-horizon setting subject to demand shocks. We show that a collusive agreement among the large firms may not only bring an output contraction but also an output expansion (relative to the noncollusive output level). The latter occurs during booms, when the fringe’s market share is more important, and is due to the strategic substitutability of quantities (we will never observe an output-expanding collusion in a price-setting game). In addition and depending on the fringe’s market share the time at which maximal collusion is most difficult to sustain can be either at booms or recessions.

Welfare-enhancing collusion in the presence of a competitive fringe

Following the structure of many commodity markets, we consider a reduced number of large firms and a competitive fringe of many small suppliers choosing quantities in an infinitehorizon setting subject to demand shocks. We show that a collusive agreement among the large firms may not only bring an output contraction but also an output expansion (relative to the non-collusive output level). The latter occurs during booms, when the fringe's market share is more important, and is due to the strategic substitutability of quantities (we will never observe an output expanding collusion in a price setting game). In addition and depending on the fringe's market share the time at which collusion is most difficult to sustain can be either at booms or recessions

Confluence of Cellular Degradation Pathways During Interdigital Tissue Remodeling in Embryonic Tetrapods

Digits develop in the distal part of the embryonic limb primordium as radial prechondrogenic condensations separated by undifferentiated mesoderm. In a short time interval the interdigital mesoderm undergoes massive degeneration to determine the formation of free digits. This fascinating process has often been considered as an altruistic cell suicide that is evolutionarily-regulated in species with different degrees of digit webbing. Initial descriptions of interdigit remodeling considered lysosomes as the primary cause of the degenerative process. However, the functional significance of lysosomes lost interest among researcher and was displaced to a secondary role because the introduction of the term apoptosis. Accumulating evidence in recent decades has revealed that, far from being a unique method of embryonic cell death, apoptosis is only one among several redundant dying mechanisms accounting for the elimination of tissues during embryonic development. Developmental cell senescence has emerged in the last decade as a primary factor implicated in interdigit remodeling. Our review proposes that cell senescence is the biological process identified by vital staining in embryonic models and implicates lysosomes in programmed cell death. We review major structural changes associated with interdigit remodeling that may be driven by cell senescence. Furthermore, the identification of cell senescence lacking tissue degeneration, associated with the maturation of the digit tendons at the same stages of interdigital remodeling, allowed us to distinguish between two functionally distinct types of embryonic cell senescence, "constructive" and "destructive."This work was supported by a grant (BFU2017-84046-P) from the Spanish Science and Innovation Ministry to JM

LCA & LCCA of a PCM application to control root zone temperatures of hydroponic crops in comparison with conventional root zone heating systems

The present study analyzes the environmental and economic performance of the use of PCM as a root zone temperature control system in substitution of conventional gas, oil and biomass heating systems by using life cycle assessment (LCA) and life cycle accounting (LCCA) methodologies. This study is focused on the possible application of these systems in a multitunel greenhouse situated in southern Spain. For the study was assumed a crop productivity increase of 20% when root zone temperature control systems are applied. Results showed that gas, oil and biomass conventional heating systems reduce farmer's net benefit and increase the environmental impact of each kg of produced tomato despite the assumed increase of productivity. Significant environmental and economic benefits are obtained for PCM in relation with the use of gas and oil root zone heating systems. In relation with biomass, heating system economical advantage is obtained but environmental results are similar. When analyzing PCM scenario in comparison with conventional production without heating systems, no significant positive results were obtained. To reduce tomato production CO2 emissions and costs, yield production should increase 8.5% and 18% respectively.Postprint (published version

Effects of Berberine on the Chondrogenic Differentiation of Embryonic Limb Skeletal Progenitors

Introduction: Berberine (BBR) is an isoquinoline plant alkaloid with demonstrated anti-inflammatory, anti-tumor and immunosuppressive pharmacological properties that functions via multiple signaling pathways and epigenetic modulators. Numerous studies have proposed BBR as a promising therapeutic agent for joint cartilage degeneration, and other connective tissue diseases. Purpose and methods: This work aimed to evaluate the effects of BBR on the growth and differentiation of embryonic skeletal progenitors using the limb mesoderm micromass culture assay. Results: Our findings show that at difference of its apoptotic influence on a variety of tumor tissues, cell death was not induced in skeletal progenitors by the addition of 12 or 25 µM BBR concentration to the culture medium. Morphological and transcriptional analysis revealed dual and opposite effects of BBR treatments on chondrogenesis depending on the stage of differentiation of the cultured progenitors. At early stage of culture, BBR was a potent chondrogenic inhibitor, while chondrogenesis was intensified in treatments at advanced stages of culture. The chondrogenic promoting effect was accompanied by a moderate upregulation of gene markers of prehypertrophic cartilage, including ColXa1, alkaline phosphatase Alpl, Runx2, and Indian Hedgehog Ihh. We further observed a positive transcriptional influence of BBR in the expression of DNA methyltransferase genes, Dnmt1, Dnmt3a and Dnmt3b, suggesting a potential involvement of epigenetic factors in its effects. Conclusion: Our study uncovers a new pharmacological influence of BBR in cartilage differentiation that must be taken into account in designing clinical protocols for its employment in the treatment of cartilage degenerative diseases

Interdigital tissue regression in the developing limb of vertebrates

ABSTRACT Here we we have chosen the regression of the interdigital tissue which sculpts the digits from the hand/foot plate in tetrapod embryos to review the most relevant aspects concerning the regulation and biological significance of programmed cell death. We gather abundant information showing that the initiation of the degenerative process is the result of a complex interplay between the different signaling pathways which are also responsible for limb outgrowth and skeletal tissue differentiation, rather than being regulated by a specific signaling pathway. The model further shows that once the death response is triggered, several different routes of cell disruption, including caspase-dependent apoptosis, lysosomal-mediated cell death, and even a cell senescence process, are activated in the interdigits to ensure their elimination. Transcriptional and structural changes accompanying the degenerative process, and their posible contribution to the control of the death process, are also revised in detail. Finally we survey a number of issues still awaiting clarification, such as the functional implication of interdigital cell death as a source of signals acting on the surrounding tissues, as occurs in the so called “regenerative cell death”

Cell death in the developing vertebrate limb: A locally regulated mechanism contributing to musculoskeletal tissue morphogenesis and differentiation

Our aim is to critically review current knowledge of the function and regulation of cell death in the developing limb. We provide a detailed, but short, overview of the areas of cell death observed in the developing limb, establishing their function in morphogenesis and structural development of limb tissues. We will examine the functions of this process in the formation and growth of the limb primordia, formation of cartilaginous skeleton, formation of synovial joints, and establishment of muscle bellies, tendons, and entheses. We will analyze the plasticity of the cell death program by focusing on the developmental potential of progenitors prior to death. Considering the prolonged plasticity of progenitors to escape from the death process, we will discuss a new biological perspective that explains cell death: this process, rather than secondary to a specific genetic program, is a consequence of the tissue building strategy employed by the embryo based on the formation of scaffolds that disintegrate once their associated neighboring structures differentiate.Spanish Science and Innovation Ministry, Grant/Award Numbers: BFU2017-84046-P, BES-2015-07426

Modeling the differentiation of embryonic limb chondroprogenitors by cell death and cell senescence in high density micromass cultures and their regulation by FGF signaling

Considering the importance of programmed cell death in the formation of the skeleton during embryonic development, the aim of the present study was to analyze whether regulated cell degeneration also accompanies the differentiation of embryonic limb skeletal progenitors in high-density tridimensional cultures (micromass cultures). Our results show that the formation of primary cartilage nodules in the micromass culture assay involves a patterned process of cell death and cell senescence, complementary to the pattern of chondrogenesis. As occurs in vivo, the degenerative events were preceded by DNA damage detectable by ?H2AX immunolabeling and proceeded via apoptosis and cell senescence. Combined treatments of the cultures with growth factors active during limb skeletogenesis, including FGF, BMP, and WNT revealed that FGF signaling modulates the response of progenitors to signaling pathways implicated in cell death. Transcriptional changes induced by FGF treatments suggested that this function is mediated by the positive regulation of the genetic machinery responsible for apoptosis and cell senescence together with hypomethylation of the Sox9 gene promoter. We propose that FGF signaling exerts a primordial function in the embryonic limb conferring chondroprogenitors with their biological properties.Funding: This research was funded by a Grant (PID2021-125651NB-I00) from the Spanish Science and Innovation Ministry to J.A.M. C.D-O. is a recipient of a predoctoral grant from the University of Cantabria

Expression of Id2 in the developing limb is associated with zones of active BMP signaling and marks the regions of growth and differentiation of the developing digits

Here we report the pattern of expression of inhibitor of DNA binding/differentiation factor 2 (Id2) in the developing chicken limb. We show that prior to stage 25, Id2 is expressed in the anterior and posterior mesoderm, the AER, and in the early skeletal chondrogenic aggregates. At more advanced stages of limb development Id2 is expressed in the undifferentiated subectodermal and interdigital mesenchyme and exhibits specific domains of expression in the growing digits. These expression domains were closely coincident with zones of activation of BMP-signaling as deduced from the distribution of phosphorylated SMADs 1/5/8. In micromass cultures transcripts of Id2 are associated with the nodules of chondrogenic differentiation. Expression of Id2 both in vivo and in vitro was up-regulated in experiments of BMP-gain-offunction and down-regulated after treatments with BMP-antagonists. Interestingly, interdigital application of TGF?2 transiently upregulates Id2 in coincidence with the inhibition of interdigital cell death and the commitment of the interdigital mesenchyme to form an ectopic digit. These data suggest that Id2 is a molecular mediator of BMP signaling acting in concert with the TGF? pathway during the formation of the digits