ALBERT

Description: Diel cycles of dissolved cationic metal concentrations commonly occur in freshwater streams in apparent response to coincident cycles in water quality parameters (pH, O2, temperature). Hourly sampling of the Cd-contaminated Riou Mort (France) revealed large diel cycles in “total” dissolved Cd (232−357 nM; 〈0.45 μm) and “truly” dissolved Cd (56−297 nM; 〈0.02 μm) which were strongly correlated with changes in water pH. Using measured fluxes, a dissolved O2 model was constructed that indicated that benthic metabolic activities, respiration and photosynthesis, were responsible for the diel O2 (and thus, CO2 and pH) variation in the stream. However, microsensor measurements also showed that the pH changes occurred at the biofilm interface earlier than in the bulk water column. This difference in timing was reflected in the Cd dynamics, where pH-controlled sorption effects caused Cd partitioning from the truly dissolved pool onto the biofilm in the morning, and from the truly dissolved pool onto large colloids (0.02−0.45 μm) later in the day. Because this process causes large changes in the bioavailable Cd fraction, it has significant implications for Cd toxicity in freshwater streams. This study demonstrates the profound control of benthic microbiological processes on the cycling of heavy metals in aquatic systems.

Description: In a laboratory-based test series, seven experiments along a simulated Pacific hydrotherm at 152°W, 40°N were carried out to measure the rise velocities of liquefied CO2 droplets under (clathrate) hydrate forming conditions. The impact of a hydrate skin on the rising behavior was investigated by comparing the results with those from outside the field of hydrate stability at matching buoyancy. A thermostatted high-pressure tank was used to establish conditions along the natural oceanic hydrotherm. Under P-/T-conditions allowing hydrate formation, the majority of the droplets quickly developed a skin of CO2 hydrate upon contact with seawater. Rise rates of these droplets support the parametrization by Chen et al. (Tellus 2003, 55B, 723−730), which is based on empirical equations developed to match momentum of hydrate covered, deformed droplets. Our data do not support other parametrizations recently suggested in the literature. In the experiments from 5.7 MPa, 4.8 °C to 11.9 MPa, 2.8 °C positive and negative deviations from predicted rise rates occurred, which we propose were caused by lacking hydrate formation and reflect intact droplet surface mobility and droplet shape oscillations, respectively. This interpretation is supported by rise rates measured at P-/T-conditions outside the hydrate stability field at the same liquid CO2-seawater density difference (Δρ) matching the rise rates of the deviating data within the stability field. The results also show that droplets without a hydrate skin ascend up to 50% faster than equally buoyant droplets with a hydrate skin. This feature has a significant impact on the vertical pattern of dissolution of liquid CO2 released into the ocean. The experiments and data presented considerably reduce the uncertainty of the parametrization of CO2 droplet rise velocity, which in the past emerged partly from their scarcity and contradictions in constraints of earlier experiments.

Description: Siderophores are chelates produced by bacteria as part of a highly specific iron uptake mechanism. They are thought to be important in the bacterial acquisition of iron in seawater and to influence iron biogeochemistry in the ocean. We have identified and quantified two types of siderophores in seawater samples collected from the Atlantic Ocean. These siderophores were identified as hydroxamate siderophores, both ferrioxamine species representative of the more soluble marine siderophores characterized to date. Ferrioxamine G was widely distributed in surface waters throughout the Atlantic Ocean, while ferrioxamine E had a more varied distribution. Total concentrations of the two siderophores were between 3 and 20 pM in the euphotic zone. If these compounds are fully complexed in seawater, they represent approximately 0.2-4.6 of the 〈0.2 μm iron pool. Our data confirm that siderophore-mediated iron acquisition is important for marine heterotrophic bacteria and indicate that siderophores play an important role in the oceanic biogeochemical cycling of iron. © 2008 American Chemical Society.

Description: An increasing body of evidence suggests that much of the trace metal contamination observed in coastal waters is no longer derived from point-source inputs, but instead originates from diffuse, non-point sources. Previous research has shown that water temperature and dissolved oxygen regulate non-point source processes such as sediment diagenesis; however, limited information is available regarding the effect of these variables on toxic trace metal cycling and speciation in natural waters. Here, we present data on the seasonal variation of dissolved Cu cycling in the Long Island Sound, an urban estuary adjacent to New York City. An operationally defined chemical speciation technique based on kinetic lability and organic complexation has been applied to examine the most ecologically relevant metal fraction. In contrast to the decrease from spring to summer observed in the total dissolved Cu pool (average ± SD:  15.1 ± 4.4 nM in spring and 11.8 ± 3.5 nM in summer), our results revealed that in the highly impacted western LIS, levels of labile Cu reached higher levels in summer (range 3.6−7.7 nM) than in spring (range 1.5− 3.9 nM). Labile Cu in surface waters of the western Sound appeared to have a wastewater source during spring high flow conditions, coinciding with elevated levels of sewage-derived Ag. Labile Cu elsewhere in the LIS during spring apparently resulted from fluvial input and mixing. During summer, labile Cu increased in bottom waters (at one site, bottom water labile Cu increased from 1.5 nM in spring to 7.7 nM in summer), and covariance with tracers of diagenetic remobilization (e.g., Mn) revealed a sedimentary source. Although total dissolved Cu showed no consistent trends with water quality parameters, labile Cu in bottom waters showed an inverse correlation with dissolved oxygen and a positive, exponential correlation with water temperature. These results suggest that future increases in coastal water temperatures may cause the benthic source of labile Cu to become proportionally more significant.

Description: The origin of dissolved organic matter (DOM) within sea ice in coastal waters of the Baltic Sea was investigated using parallel factor (PARAFAC) analysis of DOM fluorescence. Sea ice DOM had distinctly different fluorescence characteristics than that of the underlying humic-rich waters and was dominated by protein-like fluorescence signals. PARAFAC analysis identified five fluorescent components, all of which were present in both sea ice and water. Three humic components were negatively correlated to salinity and concluded to be terrestrially derived material. Baltic Sea ice DOM was found to be a mixture of humic material from the underlying water column incorporated during ice formation and autochthonous material produced by organisms within the ice. Dissolved organic carbon (DOC) and nitrogen (DON) concentrations were correlated to the humic fluorescence, indicating that the majority of the organic carbon and nitrogen in Baltic Sea ice is bound in terrestrial humic material trapped within the ice. This has implications for our understanding of sea ice carbon cycling in regions influenced by riverine input (e.g., Baltic and Arctic coastal waters), as the susceptibility of DOM to degradation and remineralization is largely determined by its source.

Description: Four surveys of the Huelva Estuary in southwest Spain and its sources, the Tinto and the Odiel Rivers, were carried out between 1996 and 1998. The surveys investigated the impact of metalliferous mining of sulfide-rich ores in the catchment area on metal speciation, metal concentrations in a macrophyte, and phytoplankton diversity and abundance. Chemical speciation measurements in the lower Tinto Estuary showed that metals were predominantly electrochemically labile (>99 of total dissolved Cu, Co, and Ni at 10 μM Cu, 424 nM Co, and 500 nM Ni, S = 28). Concentrations of Cu complexing ligands and free cupric ions Cu2+ in the Gulf of Cádiz ranged between 5.3 and 38 nM and 0.2-7.9 pM, respectively, with conditional stability constants of the ligands of log K′CuL = 11.7-12.6. At enhanced dissolved Cu concentrations in the lower Huelva Estuary, Cu complexing ligands were saturated with Cu, resulting in nanomolar Cu2+, which increased upstream. Metal tissue concentrations of the macrophyte Blindingia marginata were high, and a clear relationship between dissolved labile Cu and macrophyte tissue Cu concentrations was observed. A low biodiversity was observed in the Huelva system (Shannon-Wiener indices (H) typically 〈0.2). Nevertheless, the maximum biomass was observed in the lower Tinto Estuary, which showed high labile metal and nutrient concentrations and a low biodiversity (H 〈 0.02), thereby suggesting adaptation through evolutionary processes of the phytoplankton community to the harsh conditions. © 2007 American Chemical Society.

Description: The U.S. Department of Energy's National Energy Technology Laboratory (NETL) located in Albany, OR (formerly the Albany Research Center) has studied ex situ mineral carbonation as a potential option for carbon dioxide sequestration. Studies focused on the reaction of Ca−, Fe−, and Mg−silicate minerals with gaseous CO2 to form geologically stable, naturally occurring solid carbonate minerals. The research included resource evaluation, kinetic studies, process development, and economic evaluation. An initial cost estimate of ∼$69/ton of CO2 sequestered was improved with process improvements to ∼$54/ton. The scale of ex situ mineral carbonation operations, requiring ∼55 000 tons of mineral to carbonate, the daily CO2 emissions from a 1-GW, coal-fired power plant, may make such operations impractical.

Description: Six new linear peptides, pterulamides I−VI (1−6), were isolated from the fruiting bodies of a Malaysian Pterula species. The structures were elucidated by MS and 2D NMR experiments, and the absolute configurations of the constituent amino acids established using Marfey's method. The pterulamides are mainly assembled from nonpolar N-methylated amino acids and, most interestingly, have non-amino-acid N-terminal groups, among them the unusual cinnamoyl, (E)-3-methylsulfinylpropenoyl, and (E)-3-methylthiopropenoyl groups. Furthermore, pterulamides I−V are the first natural peptides with a methylamide C-terminus. Pterulamides I and IV are cytotoxic against the P388 cell line with IC50 values of 0.55 and 0.95 μg/mL (0.79 and 1.33 μM), respectively.

Description: Secretions from the paracloacal glands of alligators (Alligator spp.) and caimans (Caiman spp., Melanosuchus niger, and Paleosuchus spp.) were examined by GC-MS. The secretions of the common caiman (C. crocodilus), the broad-snouted caiman (C. latirostris), the yacare caiman (C. yacare), the dwarf caiman (P. palpebrosus), and the smooth-fronted caiman (P. trigonatus) yielded a new family of 43 aliphatic carbonyl compounds that includes aldehydes, ketones, and β-diketones with an ethyl branch adjacent to the carbonyl group. The identification of these glandular components and the syntheses and stereochemical investigations of selected compounds are described.

Description: Using HPLC/microtiter-plate-based generation of activity profiles the extract of a marine alga-derived fungus, identified as Gliocladium sp., was shown to contain the known strongly cytotoxic metabolite 4-keto-clonostachydiol (1) and also clonostachydiol (2) as well as gliotide (3), a new cyclodepsipeptide containing several d-amino acids. The absolute configuration of 1 was elucidated by reduction to 2, and two further oxidized derivatives of clonostachydiol (5, 6) were prepared and evaluated for biological activity.

Description: After the discovery of a potent natural flavonoid glucoside as a potent inhibitor of FabI, a large flavonoid library was screened against three important enzymes (i.e., FabG, FabZ, and FabI) involved in the fatty acid biosynthesis of P. falciparum. Although flavones with a simple hydroxylation pattern (compounds 4−9) showed moderate inhibitory activity toward the enzymes tested (IC50 10−100 μM), the more complex flavonoids (12−16) exhibited strong activity toward all three enzymes (IC50 0.5−8 μM). Isoflavonoids 26−28 showed moderate (IC50 7−30 μM) but selective activity against FabZ. The most active compounds were C-3 gallic acid esters of catechins (32, 33, 37, 38), which are strong inhibitors of all three enzymes (IC50 0.2−1.1 μM). Kinetic analysis using luteolin (12) and (−)-catechin gallate (37) as model compounds revealed that FabG was inhibited in a noncompetitive manner. FabZ was inhibited competitively, whereas both compounds behaved as tight-binding noncompetitive inhibitors of FabI. In addition, these polyphenols showed in vitro activity against chloroquine-sensitive (NF54) and -resistant (K1) P. falciparum strains in the low to submicromolar range.

Description: A new cyclic pentapeptide, chrysosporide (1), was isolated from a New Zealand sample of the mycoparasitic fungus Sepedonium chrysospermum by bioactivity-guided fractionation. The planar structure was deduced by detailed spectroscopic analysis, and the absolute configurations of the amino acid residues were defined by Marfey's method. As both enantiomers of Leu occurred in chrysosporide, molecular mechanics calculations were applied to the analysis to distinguish between the possible structural isomers. Only the lowest energy conformers of the cyclo-(l-Val-d-Ala-l-Leu-l-Leu-d-Leu) isomer were in agreement with the observed NOEs, suggesting that this was the most probable amino acid sequence for chrysosporide (1).

Description: An unusual oxalylated tetramic acid, pachydermin (1), has been isolated from the New Zealand basidiomycete Chamonixia pachydermis. The full structure, which was not directly accessible by NMR methods, was deduced from that of a degradation product, 5-(3-chloro-4-hydroxybenzylidene)tetramic acid (2). The degradation product 2 exhibited mild antibacterial activity against Bacillus subtilis.

Description: Analysis of stable carbon isotope fractionation is a useful method to study the sources and fate of anthropogenic organic contaminants such as polychlorinated biphenyls (PCBs) in the environment. To evaluate the utility of carbon isotopes, determination of isotopic ratios of 13C/12C in source materials, for example, technical PCB preparations, is needed. In this study, we determined δ13C values of 31 chlorobiphenyl (CB) congeners in 18 technical PCB preparations and 15 chloronaphthalene (CN) congeners in 6 polychlorinated naphthalene preparations using two-dimensional gas chromatography−combustion furnace−isotope ratio mass spectrometry (2DGC−C−IRMS). Development of 2DGC−IRMS enabled improved resolution and sensitivity of compound-specific carbon isotope analysis (CSIA) of CB or CN congeners. δ13C values of PCB congeners ranged from −34.4 (Delors) to −22.0‰ (Sovol). Analogous PCB preparations with similar chlorine content, but different geographical origin, had different δ13C values. PCB preparations from Eastern European countriesDelors, Sovol, Trichlorodiphenyl, and Chlorofenhad distinct δ13C values. PCB mixtures showed increased 13C depletion with increasing chlorine content. δ13C values for individual CB congeners varied depending on the degree of chlorination in technical mixtures. δ13C values of CN congeners in Halowaxes ranged from −26.3 to −21.7‰ and these values are within the ranges observed for PCBs. This study establishes the range of δ13C values in technical PCB and PCN preparations, which may prove to be useful in the determination of sources of these compounds in the environment. This is the first study to employ 2DGC−IRMS analysis of δ13C values in technical PCB and PCN preparations

Description: The scientific discipline of active restoration of denuded coral reef areas has drawn much attention in the past decade as it became vident that this ecosystem does not ofte recover naturally from anthropogenic stress without manipulation. Essentially, the choices are either the continuous degradation of the reefs or active restoration to encourage reef development. As a result, worldwide restoration operations during the past decade have been recognized as being a major tool for reef rehabilitation. This situation has also stirred discussions and debates on the various restoration measures suggested as management options, supplementary to the traditional conservation acts. The present essay reviews past decade’s (1994-2004) approaches and advances in coral reef restoration. While direct coral transplantation is still the primer vehicle of operations used, the concept of in situ and ex situ coral nurseries (the gardening concept), where coral materials (nubbins, branches, spats) are maricultured to a size suitable for transplantation, has been gaining recognition. The use of nubbins (down to the size of a single or few polyps) has been suggested and employed as a unique technique for mass production of coral colonies. Restoration of ship grounding sites and the use of artificial reefs have become common tools for specific restoration needs. Substrate stabilization, 3-D structural consideration of developing colonies, and the use of molecular/biochemical tools are part of novel technology approaches developed in the past decade. Economic considerations for reef restoration have become an important avenue for evaluating success of restoration activities. It has been suggested that landscape restoration and restoration genetics are important issues to be studied. In the future, as coral reef restoration may become the dominant conservation act, there would be the need not only to develop improved protocols but also to define the conceptual bases.

Description: Sansalvamide A, a cyclic depsipeptide isolated from a marine fungus of the genus Fusarium, is composed of four hydrophobic amino acids (Phe, two Leu, Val) and one hydroxy acid ((S)-2-hydroxy-4-methylpentanoic acid; O-Leu) with five stereogenic centers all having S-stereochemistry. We have recently synthesized the corresponding cyclic peptide (Gu, W.; Liu, S.; Silverman, R. B. Organic Lett. 2002, 4, 4171−4174) and found that it too has antitumor activity. N-Methylation can enhance potency and selectivity for peptides. Consequently, here we synthesize 12 different N-methylated sansalvamide A peptide analogues and show that for several different tumor cell lines three of these analogues are more potent than the natural product; in pancreatic cells, sansalvamide A shows little activity, but the N-methylsansalvamide peptides are potent cytotoxic agents.