Elevated CO2 degassing rates prevented the return of Snowball Earth during the Phanerozoic

The Cryogenian period (~720–635 Ma) is marked by extensive Snowball Earth glaciations. These have previously been linked to CO₂ draw-down, but the severe cold climates of the Cryogenian have never been replicated during the Phanerozoic despite similar, and sometimes more dramatic changes to carbon sinks. Here we quantify the total CO₂ input rate, both by measuring the global length of subduction zones in plate tectonic reconstructions, and by sea-level inversion. Our results indicate that degassing rates were anomalously low during the Late Neoproterozoic, roughly doubled by the Early Phanerozoic, and remained comparatively high until the Cenozoic. Our carbon cycle modelling identifies the Cryogenian as a unique period during which low surface temperature was more easily achieved, and shows that the shift towards greater CO₂ input rates after the Cryogenian helped prevent severe glaciation during the Phanerozoic. Such a shift appears essential for the development of complex animal life

Probability and timing of succession or closure in family firms: a switching regression analysis of farm households in Germany

In a two-step econometric approach that corrects for selectivity bias, we analyse the determinants of the probability of succession and the timing of succession or closure in a unique sample of 233 North-German family farms. We set up the succession decision as an intertemporal optimization problem. The empirical results show that larger and more profitable farms, which are specialized in dairy production are significantly more likely to have an intra-family successor. We find that a nonagricultural education of the current manager or the successor delay succession. When the family decided to stop farming operations, nonagricultural education of the owner delays closure of the farm. Closure occurs earlier if the manager is able to lease out the land in the process of retirement. Although farm households react to incentives originating from tax and pension regulations, many important determinants of succession are beyond the control of policymakers.

Production of the haemopoietic growth factors GM-CSF and interleukin-3 by mast cells in response to IgE receptor-mediated activation

Mast cells have a central role in allergic diseases mediated by specific immunoglobulin E antibody responses to allergens. The binding of IgE to the high-affinity receptor for IgE (Fc epsilon R) on mast cells and basophils enables these cells to react specifically to allergens. Such contact leads to the activation of mast cells and the release of histamine and other pharmacological mediators, causing an immediate hypersensitivity and acute inflammatory reactions, accompanied by the development of allergic symptoms. Here we show that Fc epsilon R-mediated activation of murine mast cells results in the production of the haemopoietic growth factors granulocyte/macrophage colony-stimulating factor (GM-CSF) and interleukin-3 (IL-3). IL-3 and GM-CSF, in addition to their role in bone marrow haemopoiesis, also influence inflammation as they have the capacity to recruit, prime and activate inflammatory cells such as neutrophils, macrophages and eosinophils. Secretion of these factors by mast cells in response to allergens may therefore have an important role in local tissue defense

Mutations in the tissue inhibitor of metalloproteinases-3 (TIMP3) in patients with Sorsby's fundus dystrophy

The hereditary macular dystrophies are progressive degenerations of the central retina and contribute significantly to irreversible visual loss in developed countries. Among these disorders, Sorsby's fundus dystrophy (SFD), an autosomal dominant condition, provides an excellent mendelian model for the study of the genetically complex age-related macular degeneration (AMD), the most common maculopathy in the elderly. Recently, we mapped the SFD locus to 22q13−qter. This same region contains the gene for tissue inhibitor of metalloproteinases-3 (TIMP3), which is known to play a pivotal role in extracellular matrix remodeling. We have now identified point mutations in the TIMP3 gene in affected members of two SFD pedigrees. These mutations are predicted to disrupt the tertiary structure and thus the functional properties of the mature protein