RCP-driven α5β1 recycling suppresses Rac and promotes RhoA activity via the RacGAP1–IQGAP1 complex

Inhibition of αvβ3 or expression of mutant p53 promotes invasion into fibronectin (FN)-containing extracellular matrix (ECM) by enhancing Rab-coupling protein (RCP)–dependent recycling of α5β1 integrin. RCP and α5β1 cooperatively recruit receptor tyrosine kinases, including EGFR1, to regulate their trafficking and downstream signaling via protein kinase B (PKB)/Akt, which, in turn, promotes invasive migration. In this paper, we identify a novel PKB/Akt substrate, RacGAP1, which is phosphorylated as a consequence of RCP-dependent α5β1 trafficking. Phosphorylation of RacGAP1 promotes its recruitment to IQGAP1 at the tips of invasive pseudopods, and RacGAP1 then locally suppresses the activity of the cytoskeletal regulator Rac and promotes the activity of RhoA in this subcellular region. This Rac to RhoA switch promotes the extension of pseudopodial processes and invasive migration into FN-containing matrices, in a RhoA-dependent manner. Thus, the localized endocytic trafficking of α5β1 within the tips of invasive pseudopods elicits signals that promote the reorganization of the actin cytoskeleton, protrusion, and invasion into FN-rich ECM.     

Biogeographic patterns, β-diversity and dominance in the cerrado biome of Brazil

From a total woody flora of ca. 1000 species, a suite of 121 species forms an oligarchy dominating the cerrado biome. This mirrors patterns of dominance described in western Amazonian rain forests. Widespread sampling shows that across the biome this suite of species contributes on average 66% of the total species composition, and 75% of the total Importance Value Index in cerrado communities. An analysis of the floristic similarity between six cerrado phytogeographic provinces (southern, central and south-eastern, central-western, far-western, north-eastern, disjunct Amazonian) reveals great heterogeneity within the biome, principally of the less common species. Of the 951 species recorded from 375 floristic surveys across the biome, 494 species (more than half of the total) are found in only one of the provinces, with very few species (37, i.e., 3.9%) found in all six provinces. Each of the provinces contains a significant number of species which are apparently confined to it, ranging from 15 species (1.6% of the total woody cerrado flora) in the far-western province (primarily in the state of Rondônia) to 162 species (17%) in the central-western province. At the local level, floristic similarity can be very high. An analysis of the floristic composition of 13 sites within the Federal District shows a woody flora of 236 species, indicating that 25% of the total woody flora of the cerrado biome is represented in 0.3% of its area, illustrating the great conservation importance of this region. Floristic similarity between sites within the Federal District is high, although much of this similarity is accounted for by oligarch species which account for between 59 and 89% of total species recorded per site. Informed conservation judgements within the cerrado need to take account of regional floristic patterns to ensure maximum protection of biodiversity, as the majority of species are not geographically widespread within the biome.     

Metal-catalyzed oxidation reactions and mass spectrometry: the roles of ascorbate and different oxidizing agents in determining Cu-protein-binding sites

Further study has been made of metal-catalyzed oxidation (MCO) reactions and mass spectrometry as a method to determine the binding site of copper in metalloproteins. The role of ascorbate and a variety of oxidizing agents, including O2, H2O2, and S2O8(2-), have been investigated using Cu/Zn superoxide dismutase (SOD) as a model system. Ascorbate is found to play two competing roles in the MCO reactions. It reduces Cu(II), which initiates and maintains the generation of reactive oxygen species, and it scavenges radicals, which helps to localize oxidation products to amino acids near the metal center. An ascorbate concentration of 100 mM is found to be optimal with regard to localizing oxidation products to only the Cu-binding residues (His44, His46, His61, and His118) of Cu/Zn SOD. This concentration of ascorbate is very similar to the optimum concentration found in our previous studies of different Cu-binding proteins. Another notable result from this study is the observation that S2O8(2-) is more effective as an oxidant than O2 or H2O2 in the MCO reactions. Because S2O8(2-) is more stable in solution than H2O2, using it as an oxidizing agent results in much less nonspecific oxidation to the protein. The overall results of this study suggest that general MCO reaction conditions may exist for determining the metal-binding site of a wide range of Cu-binding proteins.     

IPBES-6: the best plenary yet?

The Intergovernmental Science-Policy Platform for Biodiversity and Ecosystem Services (IPBES) held its 6th plenary session in Medellin (Colombia) during March 2018. Several assessments were due for acceptance by the plenary. We here give news from the plenary and the platform, sketch out important key messages from the regional assessments as well as of the global thematic assessment on land degradation and restoration. We further give an outlook on the work ahead and potential for contributions from the scientific community to the important work of IPBES.     

Using GIS techniques to model the distribution of the economically important xate palm Chamaedorea ernesti‐augusti within the Greater Maya Mountains,Belize

Abstract

The purpose of this investigation was to model the distribution of the fishtail xate palm (´Chamaedorea ernesti‐augusti) and to investigate the effectiveness of using geostatistical techniques to map its distribution. The leaves of the Central American xate palm C. ernesti‐augusti are now extensively cut for the flori‐cultural industry; across its range, populations are being over‐harvested. In Central America, the Greater Maya Mountains (GMM), Belize are widely believed to be an abundance ‘hotspot’ for this species. In total, 220 sample sites were systematically located throughout the GMM, based on a fixed distance interval using the accessible track/road network. Species counts and environmental data were collected from each 20 m × 20 m plot. Statistical analyses were carried out using GenStat and Arc‐GIS. We used several semivariogram models, within bespoke GenStat procedures, to map the log‐transformed xate abundance data. Validation of models used the official GenStat Kcross‐validation procedure. Of the six models investigated in detail, the ‘Bounded Linear’ model outperformed all others and most effectively represented the spatial distribution of C. ernesti‐augusti. Environmental factors were found to have low statistical significance for the distribution of the xate palm. The predicted map shows that the geographic abundance was dominated by low xate counts; xat´ abundance values for this region appear to have been consistently overestimated in the literature. Our study showed the effectiveness of using local modelling techniques to map xate abundances and reveal local abundance hotspots. It highlighted areas needing further survey work and the need for collecting more environmental data to improve the prediction of plant distribution in this region using niche and/or co‐kriging modelling approaches. Our study suggested that the xate resource in Belize needs a careful conservation approach.     

The Intergovernmental Platform on Biodiversity and Ecosystem Services (IPBES): progress and next steps

Biodiversity and the services ecosystems provide have built the foundation of human civilization and provide for the welfare of people. With the increase of the human population it has become clearer than ever that the human exploitation of our natural resources leads to detrimental interactions between ecological and sociological systems. Only concerted and global actions will be able to reverse ongoing biodiversity loss. In response to these needs, the United Nations agreed the establishment of the Intergovernmental Platform on Biodiversity and Ecosystem Services (IPBES) in 2010. Here, we report on the progress IPBES has made since its inception, and suggest how the scientific community can engage with this important science-policy interface.