Nine wild Iberian provenances of Castanea sativa Mill. grouped in two gene pools, North Iberian Peninsula and Mediterranean, were evaluated for several adaptive traits in two provenance-progeny ...trials with the aim of evaluating the role of natural selection in shaping adaptive variation and increasing our understanding of the genetic structure of this species, as well as reporting complete information on the genetic variation among and within the studied populations. An annual growth rhythm experiment was evaluated during the first 3 years after establishment for phenology, growth, stem form and survival, and a periodic drought-stress experiment was evaluated for dry weight, growth, survival and other related drought traits in both well-watered and drought-stress treatments. The high genetic variability reported in both trials is largely due to the genetic variation among populations. The significant differences reported between quantitative genetic and neutral marker differentiation indicated the local adaptation of these populations through directional selection, mainly for phenology, growth and biomass allocation. A clinal variation among populations was determined through correlations of phenology with latitude and xerothermic index of the provenances, showing that central and southern Mediterranean populations had earlier phenology than northern populations and that drought played a relevant role in this differentiation. The significant correlation between phenological traits and the ancestry values in the Mediterranean gene pool supported the different pattern of behavior between both gene pools and also indicated the existence of two ecotypes: xeric and mesophytic ecotypes, corresponding to Mediterranean and North Iberian gene pools, respectively. The results obtained in the drought-stress experiment confirmed that, in general terms, xeric populations showed a greater adaptability to drought, with more developed root systems and higher survival than northern populations. Moreover, the genetic variability observed within populations indicated the potential response capacity of Iberian C. sativa populations to undergo fast adaptive evolution.
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The results from a carefully implemented GPS analysis, using a strategy adapted to determine accurate vertical station velocities, are presented. The stochastic properties of our globally distributed ...GPS position time series were inferred, allowing the computation of reliable velocity uncertainties. Most uncertainties were several times smaller than the 1–3 mm/yr global sea level change, and hence the vertical velocities could be applied to correct the long tide gauge records for land motion. The sea level trends obtained in the ITRF2005 reference frame are more consistent than in the ITRF2000 or corrected for Glacial‐Isostatic Adjustment (GIA) model predictions, both on the global and the regional scale, leading to a reconciled global rate of geocentric sea level rise of 1.61 ± 0.19mm/yr over the past century in good agreement with the most recent estimates.
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Herein, we present the light-induced synthesis and characterization of a La3+/spiropyran derivative complex (LaMC) and its application as a catalyst when incorporated into electrospun ...polycaprolactone (PCL) fibers. In addition to experimental methods, computational calculations were also essential to better understand the structure and electronic characteristics of LaMC. The LaMC complex was identified as a 10-coordinated structure with the La3+ ion coordinated by four oxygens from the phenolate and the carbonyl of the carboxyl acid group from both MC ligands and by six oxygens from three nitrate ligands. In addition, LaMC was capable of getting reversibly isomerized by UV or visible light cycling. All PCL fibers were successively obtained, and their morphologies, surface properties, and catalytic behavior were studied. Results showed that PCL/LaMC fibers were capable of catalyzing bis(2,4-dinitrophenyl)phosphate degradation efficiently. Complete hydrolysis was accomplished in only 1.5 days relative to the half-life time of 35 days for the uncatalyzed hydrolysis at pH 8.1 and 25 °C.
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The problem of correcting the tide gauge records for the vertical land motion upon which the gauges are settled has only been partially solved. At best, the analyses so far have included model ...corrections for one of the many processes that can affect the land stability, namely the Glacial-Isostatic Adjustment (GIA). An alternative approach is to measure (rather than to model) the rates of vertical land motion at the tide gauges by means of space geodesy. A dedicated GPS processing strategy is implemented to correct the tide gauges records, and thus to obtain a GPS-corrected set of ‘absolute’ or geocentric sea-level trends. The results show a reduced dispersion of the estimated sea-level trends after application of the GPS corrections. They reveal that the reference frame implementation is now achieved within the millimetre accuracy on a weekly basis. Regardless of the application, whether local or global, we have shown that GPS data analysis has reached the maturity to provide useful information to separate land motion from oceanic processes recorded by the tide gauges or to correct these latter. For comparison purposes, we computed the global average of sea-level change according to Douglas Douglas, B.C., 2001. Sea level change in the era of the recording tide gauge. Int. Geophys. Ser., 75, pp. 37–64. rules, whose estimate is 1.84
±
0.35 mm/yr after correction for the GIA effect Peltier, W.R., 2001. Global glacial isostatic adjustment and modern instrumental records of relative sea level history. Int. Geophys. Ser., 75, pp. 65–95.. We obtain a value of 1.31
±
0.30 mm/yr, a value which appears to resolve the ‘sea level enigma’ Munk, W., 2002. Twentieth century sea level: an enigma. Proc. Natl. Acad. Sci. U.S.A., 99(10), pp. 6550–6555.
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Herein, synthesis and characterization of a cobalt (II) complex using a spiropyran as its ligand was described. Solid complex (CoMC) was obtained using a novel ultraviolet radiation-induced ...precipitation technique, FTIR-ATR spectroscopy demonstrated the binding sites involved in the coordination. Computational calculations were crucial to understand the experimental results, demonstrating the frontiers orbitals in tetrahydrofuran. Moreover, mass spectrometry revealed a 1:2 Co(II):ligand stoichiometry. By means of UV–vis absorption spectroscopy, complexation was confirmed and photochromic and the solvatochromic characteristics of the complex and the free ligand were studied. These results showed that the complex did not present a would be expected pattern regarding its solvatochromic properties, while the free ligand did. Reversibility experiments exposed a high resistance to photodegradation of the complex in isopropanol, comparing to the other solvents tested.
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•Complex precipitated through novel ultraviolet induced process.•Ligand and complex presented well pronounced solvatochromic properties.•Isopropanol reduced drastically the complex photodegradation characteristic.
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A data archeology exercise was carried out on sea level observations recorded during the transit of Venus across the Sun observed in 1874 from Saint Paul Island (38°41′S, 77°31 E) in the southern ...Indian Ocean. Historical (1874) and recent (1994–2009) sea level observations were assembled into a consistent time series. A thorough check of the data and its precise geodetic connection to the same datum was only possible thanks to the recent installation of new technologies (GPS buoy and radar water level sensor) and leveling campaigns. The estimated rate of relative sea level change, spanning the last 135 years at Saint Paul Island, was not significantly different from zero (−0.1 ± 0.3 mm yr−1), a value which could be reconciled with estimates of global average sea level rise for the 20th century assuming the DORIS vertical velocity estimate at Amsterdam Island (100 km distant) could be applied to correct for the land motion at the tide gauge. Considering the scarcity of long‐term sea level data in the Southern Hemisphere, the exercise provides an invaluable additional observational constraint for further investigations of the spatial variability of sea level change, once vertical land rates can be determined.
Summary
The molecular regulation of methane oxidation in the first fully authenticated facultative methanotroph Methylocella silvestris BL2 was assessed during growth on methane and acetate. Problems ...of poor growth of Methylocella spp. in small‐scale batch culture were overcome by growth in fermentor culture. The genes encoding soluble methane monooxygenase were cloned and sequenced, which revealed that the structural genes for soluble methane monooxygenase, mmoXYBZDC, were adjacent to two genes, mmoR and mmoG, encoding a σ54 transcriptional activator and a putative GroEL‐like chaperone, located downstream (3′) of mmoC. Transcriptional analysis revealed that the genes were all cotranscribed from a σ54‐dependent promoter located upstream (5′) of mmo X. The transcriptional start site was mapped. Transcriptional analysis of soluble methane monooxygenase genes and expression studies on fermentor grown cultures showed that acetate repressed transcription of sMMO in M. silvestris BL2. The possibility of the presence of a particulate, membrane‐bound methane monooxygenase enzyme in M. silvestris BL2 and the copper‐mediated regulation of soluble methane monooxygenase was investigated. Both were shown to be absent. A promoter probe vector was constructed and used to assay transcription of the promoter of the soluble methane monoxygenase genes of M. silvestris BL2 grown under various conditions and with different substrates. These data represent the first insights into the molecular physiology of a facultative methanotroph.
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A novel esterase gene (estI) of Lactobacillus casei CL96 was localized on a 3.3-kb BamHI DNA fragment containing an open reading frame (ORF) of 1,800 bp. The ORF of estI was isolated by PCR and ...expressed in Escherichia coli, the methylotrophic bacterium Methylobacterium extorquens, and the methylotrophic yeast Pichia pastoris under the control of T7, methanol dehydrogenase (P(mxaF)), and alcohol oxidase (AOX1) promoters, respectively. The amino acid sequence of EstI indicated that the esterase is a novel member of the GHSMG family of lipolytic enzymes and that the enzyme contains a lipase-like catalytic triad, consisting of Ser325, Asp516, and His558. E. coli BL21(DE3)/pLysS containing estI expressed a novel 67.5-kDa protein corresponding to EstI in an N-terminal fusion with the S · tag peptide. The recombinant L. casei CL96 EstI protein was purified to electrophoretic homogeneity in a one-step affinity chromatography procedure on S-protein agarose. The optimum pH and temperature of the purified enzyme were 7.0 and 37°C, respectively. Among the pNP (p-nitrophenyl) esters tested, the most selective substrate was pNP-caprylate (C8), with K(m) and k(cat) values of 14 ± 1.08 microliter and 1,245 ± 42.3 S-1, respectively.
The typical phytoplankton succession scenario in coastal upwelling zones is high diatom growth during upwelling and flagellate dominance during water column stratification. Within the ...diatom/flagellate succession there exist short-term changes in diatom communities that are caused by physical, chemical and biological processes. In this study, we used an improved 2-D kinematic box model to assess the influence of these processes on diatom dynamics in an estuarine ecosystem affected by coastal upwelling. This model enabled us to separate hydrographic from biogeochemical processes occurring in the estuary. Hydrographic variables, nutrient concentrations and phytoplankton composition were determined over a 2 wk period in the Ría de Vigo, NW Spain. Two major hydrographic phases were identified which coincided with a clear temporal and spatial separation between 2 diatom assemblages:Thalassiosiraspp./Skeletonema costatumandChaetocerosspp./Cerataulina pelagica. During upwelling, horizontal (6.6 km d–1) and vertical (11.7 m d–1) convective fluxes were high, causing a net input of NO₃⁻, HPO₄2–and SiO₄H₄. During this phase theThalassiosiraspp./S. costatumstanding stock was high (>20 μmol C l–1). Hydrographic processes, however, affected theThalassiosiraspp./S. costatumassemblage more than biogeochemical processes and this resulted in the net loss of this assemblage from the Ría and its export towards the shelf. There was a significant correlation between the biogeochemical variations in this diatom assemblage and silicate, suggesting a strong dependency ofThalassiosiraspp./S. costatumon this nutrient. By comparison, due to the higher carbon-specific net growth rate of theChaetocerosspp./C. pelagicaassemblage (0.35 d–1) during upwelling, this assemblage maintained a high biomass in the Ría. Upwelling was followed by upwelling relaxation when horizontal (1.9 km d–1) and vertical fluxes (1.8 m d–1) were reduced and nutrient levels diminished. During upwelling relaxation there was an accumulation ofChaetocerosspp./C. pelagicabiomass (>18 μmol C l–1). Biogeochemical processes provoked a loss ofThalassiosiraspp./S. costatumdue to rapid sedimentation and a net increase inChaetocerosspp./C. pelagica. It is suggested that the accumulation ofChaetocerosspp. is aided by a lower sinking rate whereas the selection ofC. pelagicais more dependent on NO₃⁻ and HPO₄2–consumption. It is concluded that upwelling events in the Ría cause the exportation ofThalassiosiraspp./S. costatumstanding stock from the Ría towards the shelf, which will ultimately benefit shelf pelagic and benthic fish communities. Upwelling relaxation events favour the retention of a high standing stock ofChaetocerosspp./C. pelagica, which is then directly available to the shellfish aquaculture of the Ría.
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Methylotrophic (methanol-utilizing) bacteria offer great potential as cell factories in the production of numerous products from biomass-derived methanol. Bio-methanol is essentially a non-food ...substrate, an advantage over sugar-utilizing cell factories. Low-value products as well as fine chemicals and advanced materials are envisageable from methanol. For example, several methylotrophic bacteria, including Methylobacterium extorquens, can produce large quantities of the biodegradable polyester polyhydroxybutyric acid (PHB), the best known polyhydroxyalkanoate (PHA). With the purpose of producing second-generation PHAs with increased value, we have explored the feasibility of using M. extorquens for producing functionalized PHAs containing C-C double bonds, thus, making them amenable to future chemical/biochemical modifications for high value applications.
Our proprietary M. extorquens ATCC 55366 was found unable to yield functionalized PHAs when fed methanol and selected unsaturated carboxylic acids as secondary substrates. However, cloning of either the phaC1 or the phaC2 gene from P. fluorescens GK13, using an inducible and regulated expression system based on cumate as inducer (the cumate switch), yielded recombinant M. extorquens strains capable of incorporating modest quantities of C-C double bonds into PHA, starting from either C6= and/or C8=. The two recombinant strains gave poor results with C11=. The strain containing the phaC2 gene was better at using C8= and at incorporating C-C double bonds into PHA. Solvent fractioning indicated that the produced polymers were PHA blends that consequently originated from independent actions of the native and the recombinant PHA synthases.
This work constitutes an example of metabolic engineering applied to the construction of a methanol-utilizing bacterium capable of producing functionalized PHAs containing C-C double bonds. In this regard, the PhaC2 synthase appeared superior to the PhaC1 synthase at utilizing C8= as source of C-C double bonds and at incorporating C-C double bonds into PHA from either C6= or C8=. The M. ex-phaC2 strain is, therefore, a promising biocatalyst for generating advanced (functionalized) PHAs for future high value applications in various fields.
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