Growth of Methylacidiphilum fumariolicum SolV, an extremely acidophilic methanotrophic microbe isolated from an Italian volcanic mudpot, is shown to be strictly dependent on the presence of lanthanides, a group of rare earth elements (REEs) such as lanthanum (Ln), cerium (Ce), praseodymium (Pr) and neodymium (Nd). After fractionation of the bacterial cells and crystallization of the methanol dehydrogenase (MDH), it was shown that lanthanides were essential as cofactor in a homodimeric MDH comparable with one of the MDHs of Methylobacterium extorquens AM1. We hypothesize that the lanthanides provide superior catalytic properties to pyrroloquinoline quinone (PQQ)-dependent MDH, which is a key enzyme for both methanotrophs and methylotrophs. Thus far, all isolated MxaF-type MDHs contain calcium as a catalytic cofactor. The gene encoding the MDH of strain SolV was identified to be a xoxF-ortholog, phylogenetically closely related to mxaF. Analysis of the protein structure and alignment of amino acids showed potential REE-binding motifs in XoxF enzymes of many methylotrophs, suggesting that these may also be lanthanide-dependent MDHs. Our findings will have major environmental implications as metagenome studies showed (lanthanide-containing) XoxF-type MDH is much more prominent in nature than MxaF-type enzymes.

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The retromer complex is involved in the retrograde transport of the CI-M6PR (cation-independent mannose 6-phosphate receptor) from endosomes to the Golgi. It is a hetero-trimeric complex composed of Vps26 (vacuolar sorting protein 26), Vps29 and Vps35 proteins, which are conserved in eukaryote evolution. Recently, elucidation of the crystal structure of Vps29 revealed that Vps29 contains a metallo-phosphoesterase fold [Wang, Guo, Liang, Fan, Zhu, Zang, Zhu, Li, Teng, Niu et al. (2005) J. Biol. Chem. 280, 22962-22967; Collins, Skinner, Watson, Seaman and Owen (2005) Nat. Struct. Mol. Biol. 12, 594-602]. We demonstrate that recombinant hVps29 (human Vps29) displays in vitro phosphatase activity towards a serine-phosphorylated peptide, containing the acidic-cluster dileucine motif of the cytoplasmatic tail of the CI-M6PR. Efficient dephosphorylation required the additional presence of recombinant hVps26 and hVps35 proteins, which interact with hVps29. Phosphatase activity of hVps29 was greatly decreased by alanine substitutions of active-site residues that are predicted to co-ordinate metal ions. Using inductively coupled plasma MS, we demonstrate that recombinant hVps29 binds zinc. Moreover, hVps29-dependent phosphatase activity is greatly reduced by non-specific and zinc-specific metal ion chelators, which can be completely restored by addition of excess ZnCl2. The binuclear Zn2+ centre and phosphate group were modelled into the hVps29 catalytic site and pKa calculations provided further insight into the molecular mechanisms of Vps29 phosphatase activity. We conclude that the retromer complex displays Vps29-dependent in vitro phosphatase activity towards a serinephosphorylated acidic-cluster dileucine motif that is involved in endosomal trafficking of the CI-M6PR. The potential significance of these findings with respect to regulation of transport of cycling trans-Golgi network proteins is discussed.

28Seagrass beds are highly productive coastal ecosystems providing a large array of 29 ecosystem services including fisheries and carbon sequestration. As seagrasses are known 30 to be highly sensitive to anthropogenic forcing, we evaluated the use of trace metal 31 concentrations in seagrasses as bioindicators for trace metal pollution of coastal regions at 32 both global and local scale. We carried out a meta-analysis based on literature data to 33 provide a global benchmark list for trace metal accumulation in seagrasses, which was 34 lacking in literature. We subsequently carried out a case study at the Caribbean islands of 35Curaçao and Bonaire to test for local-scale differences in trace metal concentrations in 36 seagrasses, and internal metal allocation. The benchmark and local study show that trace 37 metal concentrations in seagrass leaves, regardless of the species, can vary over a 100 to Billions of people live in coastal areas all over the world and it is expected that, in a couple of 50 decades, even more than 50 % of the expanding human population will be living within 150 51 km from the shore (Cohen, 2003; Cohen et al., 1997; Small and Nicholls, 2003). This leads 52 to a steep increase in anthropogenic activities in coastal areas such as dredging, 53 aquaculture, industrial activities and pollution, sewage discharge, and deforestation (Cohen, 54 2003; Mora, 2008). These activities severely threaten coastal ecosystems including coral 55 reefs (Mumby et al., 2006; Mumby et al., 2007), mangroves (Valiela et al., 2001) and 60To get insight into the extent and the spatial variation of anthropogenic pressure on 61 coastal ecosystems and to locate sources of pollution, there is a strong need for good 62 indicators. Bioindicators, including a variety of organisms such as clams, plants, copepods 63 and microorganisms, can be used to identify anthropogenic disturbances and preferentially 64provide early warning signals for pollution or degradation (Linton and Warner, 2003). As they 65 accumulate pollutants, these organisms also reflect low intensity, but chronic impacts, in 66 contrast to physical or chemical parameters which often only present a snapshot of 67 environmental conditions (Linton and Warner, 2003). Additionally, bioindicators can provide 68 information on multiple spatial scales, as most ecosystems are heterogeneous, and are able 69 to differentiate between natural variation and anthropogenic disturbance (Markert et al., 70 1999; Martínez-Crego et al., 2008). 71Seagrasses are known to be good bioindicators (Lee et al., 2004; Orth et al., 2006) 72 as they are widespread and sensitive to environmental changes (Bhattacharya et al., 2003; 73 Ferrat et al., 2003; Udy and Dennison, 1997; Walker and McComb, 1992), and are able to 74 integrate ecological conditions and processes over various timescales from weeks to years 75 4 (Gonzalez-Correa et al., 2005; Madden et al., 2009; Meehan and West, 2000 Royo et al., 2011; Montefalcone, 2009; Moreno et al., 2001; Romero et al., 2...

The zebra mussel, Dreissena polymorpha is an aquatic nuisance invasive species originally native to the Ponto-Caspian region where it is found in lakes and delta areas of large rivers draining into the Black and Caspian seas. The dispersal of D. polymorpha began at the end of the 18th century, at a time when shipping trade become increasingly important and many canals were built for linking different navigable river systems in Europe. Over the past 200 years, zebra mussels spread to most of the lakes, rivers and waterways in Europe by a combination of natural and anthropogenic dispersal mechanisms. D. polymorpha invaded Spain around 2001, being found for the first time in the Riba-roja reservoir at the lower part of the Ebro River, NorthEast Spain. The relatively late invasion of Spain was most likely caused by the presence of the Pyrenees, which isolated the Iberian Peninsula from the rest of the European continent, and acted as a barrier to the dispersal of D. polymorpha. In recent studies, 123Biol Invasions (2009( ) 11:2147( -2159( DOI 10.1007 molecular genetic methods have successfully been used to determine phylo-geographic relationships, which may reflect invasion corridors and can help retrace source populations. Zebra mussels from populations in Great Britain, The Netherlands, Belgium, France, Germany, Spain, Italy, Romania and North America were analyzed using PCR based amplified fragment length polymorphism (AFLP)-fingerprinting to determine the source population of D. polymorpha in Spain. The phylogenetic analyses and pair-wise genetic distances revealed that the recent invasion of zebra mussels in Spain is most likely from France.