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Most of the policy debate surrounding the actions needed to mitigate and adapt to anthropogenic climate change has been framed by observations of the past 150 years and climate and sea-level projections for the twenty-first century. The focus on this 250-year window, however, obscures some of the most profound problems associated with climate change. Here, we argue that the twentieth and twenty-first centuries, a period during which the overwhelming majority of human-caused carbon emissions are likely to occur, need to be placed into a long-term context, including the past 20 millennia, when the last Ice Age ended and human civilization developed, and the next 10 millennia, over which time the projected impacts of anthropogenic climate change will grow and persist. This long-term perspective illustrates that policy decisions made in the next few years to decades will have profound impacts on global climate, ecosystems, and human societies — not just for this century, but for the next ten millennia and beyond.

IgA nephropathy (IgAN) is the most common primary glomerulonephritis in the world. Aberrantly glycosylated IgA1, with galactose (Gal)-deficient hinge region (HR) O-glycans, plays a pivotal role in the pathogenesis of the disease. It is not known whether the glycosylation defect occurs randomly or preferentially at specific sites. We have described the utility of activated ion-electron capture dissociation (AI-ECD) mass spectrometric analysis of IgA1 O-glycosylation. However, locating and characterizing the entire range of O-glycan attachment sites are analytically challenging due to the clustered serine and threonine residues in the HR of IgA1 heavy chain. To address this problem, we analyzed all glycoforms of the HR glycopeptides of a Gal-deficient IgA1 myeloma protein, mimicking the aberrant IgA1 in patients with IgAN, by use of a combination of IgA-specific proteases + trypsin and AI-ECD Fourier transform ion cyclotron resonance (FT-ICR) tandem mass spectrometry (MS/MS). The IgA-specific proteases provided a variety of IgA1 HR fragments that allowed unambiguous localization of all O-glycosylation sites in the six most abundant glycoforms, including the sites deficient in Gal. Additionally, this protocol was adapted for on-line liquid chromatography (LC)-AI-ECD MS/MS and LC-electron transfer dissociation MS/MS analysis. Our results thus represent a new clinically relevant approach that requires ECD/electron transfer dissociation-type fragmentation to define the molecular events leading to pathogenesis of a chronic kidney disease. Furthermore, this work offers generally applicable principles for the analysis of clustered sites of O-glycosylation.

International audience; The Sample Analysis at Mars (SAM) instrument on the Curiosity rover is designed to determine the inventory of organic and inorganic volatiles thermally evolved from solid samples using a combination of evolved gas analysis (EGA), gas chromatography mass spectrometry (GCMS), and tunable laser spectroscopy [1]. The first sample analyzed by SAM at the Rocknest (RN) aeolian deposit revealed chlorohydrocarbons derived primarily from reactions between a martian oxychlorine phase (e.g. perchlorate) and terrestrial carbon from N-methyl-N-(tert-butyl-dimethylsilyl)trifluoroacetamide (MTBSTFA) vapor present in the SAM instrument background [2]. No conclusive evidence for martian chlorohydrocarbons in the RN sand was found [2]. After RN, Curiosity trav-eled to Yellowknife Bay and drilled two holes separated by 2.75 m designated John Klein (JK) and Cumber-land (CB). Analyses of JK and CB by both SAM and the CheMin x-ray diffraction instrument revealed a mudstone (called Sheepbed) consisting of ~20 wt% smectite clays [3], which on Earth are known to aid the concentration and preservation of organic matter. Last year at LPSC we reported elevated abundances of chlorobenzene (CBZ) and a more diverse suite of chlorinated hydrocarbons including dichloroalkanes in CB compared to RN, suggesting that martian or mete-oritic organic compounds may be preserved in the mudstone [4]. Here we present SAM data from additional analyses of the CB sample and of Confidence Hills (CH), another drill sample collected at the base of Mt. Sharp. This new SAM data along with supporting laboratory analog experiments indicate that most of the chlorobenzene detected in CB is derived from martian organic matter preserved in the mudstone [5].

NifU is a homodimeric modular protein comprising N- and C-terminal domains and a central domain with a redox-active [2Fe-2S](2+,+) cluster. It plays a crucial role as a scaffold protein for the assembly of the Fe-S clusters required for the maturation of nif-specific Fe-S proteins. In this work, the time course and products of in vitro NifS-mediated iron-sulfur cluster assembly on full-length NifU and truncated forms involving only the N-terminal domain or the central and C-terminal domains have been investigated using UV-vis absorption and Mössbauer spectroscopies, coupled with analytical studies. The results demonstrate sequential assembly of labile [2Fe-2S](2+) and [4Fe-4S](2+) clusters in the U-type N-terminal scaffolding domain and the assembly of [4Fe-4S](2+) clusters in the Nfu-type C-terminal scaffolding domain. Both scaffolding domains of NifU are shown to be competent for in vitro maturation of nitrogenase component proteins, as evidenced by rapid transfer of [4Fe-4S](2+) clusters preassembled on either the N- or C-terminal domains to the apo nitrogenase Fe protein. Mutagenesis studies indicate that a conserved aspartate (Asp37) plays a critical role in mediating cluster transfer. The assembly and transfer of clusters on NifU are compared with results reported for U- and Nfu-type scaffold proteins, and the need for two functional Fe-S cluster scaffolding domains on NifU is discussed.

The role of the three conserved cysteine residues on Azotobacter vinelandii IscU in accepting sulfane sulfur and forming a covalent complex with IscS has been evaluated using electrospray-ionization mass spectrometry studies of variants involving individual cysteine-to-alanine substitutions. The results reveal that IscS can transfer sulfur to each of the three alanine-substituted forms of IscU to yield persulfide or polysulfide species, and formation of a heterodisulfide covalent complex between IscS and Cys37 on IscU. It is concluded that S transfer from IscS to IscU does not involve a specific cysteine on IscU or the formation of an IscS–IscU heterodisulfide complex.

The NifU protein is a homodimer that is proposed to provide a molecular scaffold for the assembly of [Fe-S] clusters uniquely destined for the maturation of the nitrogenase catalytic components. There are three domains contained within NifU, with the N-terminal domain exhibiting a high degree of primary sequence similarity to a related family of [Fe-S] cluster biosynthetic scaffolds designated IscU. The C-terminal domain of NifU exhibits sequence similarity to a second family of proposed [Fe-S] cluster biosynthetic scaffolds designated Nfu. Genetic experiments described here involving amino acid substitutions within the N-terminal and C-terminal domains of NifU indicate that both domains can separately participate in nitrogenase-specific [Fe-S] cluster formation, although the N-terminal domain appears to have the dominant function. These in vivo experiments were supported by in vitro [Fe-S] cluster assembly and transfer experiments involving the activation of an apo-form of the nitrogenase Fe protein.

The crystal structure of a nitrogenase Fe protein single site deletion variant reveals a distinctly new conformation of the Fe protein and indicates that, upon binding of MgATP, the Fe protein undergoes a dramatic conformational change that is largely manifested in the rigid-body reorientation of the homodimeric Fe protein subunits with respect to one another. The observed conformational state allows the rationalization of a model of structurally and chemically complementary interactions that occur upon initial complex formation with the MoFe protein component that are distinct from the protein-protein interactions that have been characterized previously for stabilized nitrogenase complexes. The crystallographic results, in combination with complementary UV-visible absorption, EPR, and resonance Raman spectroscopic data, indicate that the [4Fe-4S] cluster of both the Fe protein deletion variant and the native Fe protein in the presence of MgATP can reversibly cycle between a regular cubane-type [4Fe-4S] cluster in the reduced state and a cleaved form involving two [2Fe-2S] fragments in the oxidized state. Resonance Raman studies indicate that this novel cluster conversion is induced by glycerol, and the crystallographic data suggest that glycerol is bound as a bridging bidentate ligand to both [2Fe-2S] cluster fragments in the oxidized state.

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Analysis of the genome of the hyperthermophilic bacterium Aquifex aeolicus has revealed the presence of a previously undetected gene potentially encoding a plant- and mammalian-type [2Fe-2S] ferredoxin. Expression of that gene in Escherichia coli has yielded a novel thermostable [2Fe-2S] ferredoxin (designated ferredoxin 5) whose sequence is most similar to those of ferredoxins involved in the assembly of iron-sulfur clusters (Isc-Fd). It nevertheless differs from the latter proteins by having deletions near its N- and C-termini, and no cysteine residues other than those involved in [2Fe-2S] cluster coordination. Resonance Raman, low-temperature MCD and EPR studies show close spectral similarities between ferredoxin 5 and the Isc-Fd from Azotobacter vinelandii. Mössbauer spectra of the reduced protein were analyzed with an S = 1/2 spin Hamiltonian and interpreted in the framework of the ligand field model proposed by Bertrand and Gayda. The redox potential of A. aeolicus ferredoxin 5 (-390 mV) is in keeping with its relatedness to Isc-Fd. Unfolding experiments showed that A. aeolicus ferredoxin 5 is highly thermostable (T(m) = 106 degrees C at pH 7), despite being devoid of features (e.g., high content of charged residues) usually associated with extreme thermal stability. Searches for genes potentially encoding plant-type [2Fe-2S] ferredoxins have been performed on the sequenced genomes of hyperthermophilic organisms. None other than the two proteins from A. aeolicus were retrieved, indicating that this otherwise widely distributed group of proteins is barely represented among hyperthermophiles.

International audience; We have confirm the presence of MTBSTFAby-productsin the EGA and GC-TCD-MS background signals. Major part of aromatic detected compoundson marscould be generate from the degradation of the Tenax® trap or from the MTBSTFA reaction. the possible range of products that might be produced by the SAMbackground and the Tenax trap are being elucidated by laboratory studies and it will help clarify which of the compoiunds observed by SAM are indi-geneous.

International audience; The Sample Analysis at Mars (SAM) instrument on the Curiosity rover is designed to determine the inventory of organic and inorganic vola-tiles thermally evolved from solid samples using a combination of evolved gas analysis (EGA), gas chromatography mass spectrometry (GCMS), and tunable laser spectroscopy [1]. The first solid samples analyzed by SAM, a scoop of windblown dust and sand at Rocknest (RN), revealed chlorinated hydrocarbons derived primarily from reactions between a martian oxychlorine phase (e.g. perchlorate) and terrestrial carbon from N-methyl-N-(tert-butyldimethylsilyl)-trifluoroacetamide (MTBSTFA) vapor present in the SAM instrument background [2]. Chlorobenzene (CBZ) was also identified by SAM GCMS at RN at trace levels (~0.007 nmol) and was attributed to the reaction of chlorine with the Tenax polymers used in the hydrocarbon traps [2]. After the RN analyses, Curiosity traveled to Yellowknife Bay and drilled two separate holes designated John Klein (JK) and Cum-berland (CB). Analyses of JK and CB by both SAM and the CheMin x-ray diffraction instrument revealed a mudstone consisting of ~20 wt% smectite clays [3,4], which on Earth are known to aid the concentration and preservation of organic matter. In addition, higher abundances and a more diverse suite of chlorinated hydrocarbons in CB compared to RN suggests that martian or meteoritic organic sources may be preserved in the mudstone [3]. Here we discuss the SAM EGA and GCMS measurements of volatiles released from the Sheepbed mud-stone. We focus primarily on the elevated CBZ detections at CB and laboratory analog experiments conducted to help determine if CBZ is derived from primarily terrestrial, martian, or a combination of sources.

International audience; One of the main goals of the Mars Science Laboratory is to determine whether the planet ever had environmental conditions able to support mi-crobial life. Nitrogen is a fundamental element for life, and is present in structural (e.g., proteins), catalytic (e.g., enzymes and ribozymes), energy transfer (e.g.,ATP) and information storage (RNA and DNA) bio-molecules. Planetary models suggest that molecularnitrogen was abundant in the early Martian atmosphere, but was rapidly lost to space by photochemistry, sput-tering [1, 2], impact erosion [3], and oxidized and de-posited to the surface as nitrate [4]. Nitrates are a fun-damental source for nitrogen to terrestrial microorgan-isms. Therefore, the detection of nitrates in soils and rocks is important to assess the habitability of a Mar-tian environment. SAM is capable of detecting nitrates by their thermal decomposition into nitric oxide, NO [5]. Here we analyze the release of NO from soils and rocks examined by the SAM instrument at Gale crater, and discuss its origin.

Surface air temperature is an important climatic variable that drives the hydrological cycle. Precipitation and runoff production are impacted by surface air temperature changes and are, therefore, important for water resources planning, irrigation and agriculture. Focusing on the Sutlej Basin in the Himalayan region, the present research is aimed at utilizing observational evidence to evaluate the response of the region to global warming through investigation of temperature trends. Trends in long-term average annual and seasonal surface air temperature, and several temperature indices at eight stations in the Sutlej River basin have been examined using Mann-Kendall non-parametric test. Six stations exhibited increasing trends in annual average maximum temperature with two being statistically significant. The trends in annual average minimum temperature were mixed; three of eight stations exhibited statistically significant decreasing trends. Some higher elevation stations exhibited clear warming trends both in maximum and minimum temperatures. Analysis of seasonal temperature data indicated that the warming was more pronounced in winter and spring than in summer and autumn. Trends in temperature indices considered in this paper were predominantly increasing. The predominant pattern of increased warming in the basin could have implications for water availability as the snow and glacier melt contribution to annual runoff at Bhakra reservoir is estimated at 59%. The analysis shows that even within a small area, there is variability in the magnitude and direction of historic temperature trends. Some of these variations could be partially attributed to data reliability.