The discovery of Hepatocyte Growth Factor (HGF) and its significance for cell biology, life sciences and clinical medicine

It has been more than 25 years since HGF was discovered as a mitogen of hepatocytes. HGF is produced by stromal cells, and stimulates epithelial cell proliferation, motility, morphogenesis and angiogenesis in various organs via tyrosine phosphorylation of its receptor, c-Met. In fetal stages, HGF-neutralization, or c-Met gene destruction, leads to hypoplasia of many organs, indicating that HGF signals are essential for organ development. Endogenous HGF is required for self-repair of injured livers, kidneys, lungs and so on. In addition, HGF exerts protective effects on epithelial and non-epithelial organs (including the heart and brain) via anti-apoptotic and anti-inflammatory signals. During organ diseases, plasma HGF levels significantly increased, while anti-HGF antibody infusion accelerated tissue destruction in rodents. Thus, endogenous HGF is required for minimization of diseases, while insufficient production of HGF leads to organ failure. This is the reason why HGF supplementation produces therapeutic outcomes under pathological conditions. Moreover, emerging studies delineated key roles of HGF during tumor metastasis, while HGF-antagonism leads to anti-tumor outcomes. Taken together, HGF-based molecules, including HGF-variants, HGF-fragments and c-Met-binders are available as regenerative or anti-tumor drugs. Molecular analysis of the HGF-c-Met system could provide bridges between basic biology and clinical medicine

Magnetotelluric measurements in the Alboran Sea

T23C-2284 The PICASSO program aims to understand the tectonic history of the western Mediterranean, between Spain and Morocco, where conflicting models have suggested that the region is either a relict subduction system or a zone of mantle delamination. As part of this program we successfully deployed 12 seafloor MT instruments in water depths greater than 800m in the Alboran sea. We plan to deploy additional instruments in the fall of 2010. An initial analysis of the data shows complex MT response functions with strong distortion due to seafloor topography and coast effect. This coast effect suggests a fairly resistive lithosphere beneath the seafloor, which is confirmed after inspection of the preliminary responses. We will present the data collected thus far, along with preliminary models of the profiles collected

Increasing nutrient stress reduces the efficiency of energy transfer through planktonic size spectra

Size-spectral approaches quantify the efficiency of energy transfer through food webs, but theory and field studies disagree over how changes in temperature, nutrients, and extreme weather impact on this efficiency. We address this at two scales: via 6 years of weekly sampling of the plankton size spectrum at the Plymouth L4 shelf sea site, and via a new, global-scale, meta-analysis of aquatic size spectra. The time series showed that with summertime nutrient starvation, the energy transfer efficiency from picoplankton to macroplankton decreased (i.e., steepening slopes of the size spectra). This reflected increasing dominance by small cells and their microbial consumers. The extreme storms in winter 2013/2014 caused high metazoan mortality, steep size-spectral slopes, and reduced plankton biomass. However, recovery was within months, demonstrating an inbuilt resilience of the system. Both L4 and our meta-analysis showed steep slopes of normalized size spectra (median −1.11). This reflects much lower values, either of trophic transfer efficiency (3.5%) or predator–prey mass ratio (569), compared to commonly quoted values. Results from the meta-analysis further showed that to represent energy transfer faithfully, size spectra are best constructed in units of carbon mass and not biovolume, and span a mass range of > 107. When this range is covered, both the meta-analysis and time series show a dome-shaped relationship between spectral slopes and plankton biomass, with steepening slopes under increasingly oligotrophic and eutrophic conditions. This suggests that ocean warming could decrease the efficiency of energy transfer through pelagic food webs via indirect effects of increasing stratification and nutrient starvation