Methanol acetaldehyde and acetone in the surface waters of the Atlantic Ocean

Oceanic methanol, acetaldehyde, and acetone concentrations were measured during an Atlantic Meridional Transect (AMT) cruise from the UK to Chile (49°N to 39°S) in 2009. Methanol (48–361 nM) and acetone (2–24 nM) varied over the track with enrichment in the oligotrophic Northern Atlantic Gyre. Acetaldehyde showed less variability (3–9 nM) over the full extent of the transect. These oxygenated volatile organic compounds (OVOCs) were also measured subsurface, with methanol and acetaldehyde mostly showing homogeneity throughout the water column. Acetone displayed a reduction below the mixed layer. OVOC concentrations did not consistently correlate with primary production or chlorophyll-a levels in the surface Atlantic Ocean. However, we did find a novel and significant negative relationship between acetone concentration and bacterial leucine incorporation, suggesting that acetone might be removed by marine bacteria as a source of carbon. Microbial turnover of both acetone and acetaldehyde was confirmed. Modeled atmospheric data are used to estimate the likely air-side OVOC concentrations. The direction and magnitude of air-sea fluxes vary for all three OVOCs depending on location. We present evidence that the ocean may exhibit regions of acetaldehyde under-saturation. Extrapolation suggests that the Atlantic Ocean represents an overall source of these OVOCs to the atmosphere at 3, 3, and 1 Tg yr−1 for methanol, acetaldehyde, and acetone, respectively.

Light enhanced amino acid uptake by dominant bacterioplankton groups in surface waters of the Atlantic Ocean

35S-Methionine and 3H-leucine bioassay tracer experiments were conducted on two meridional transatlantic cruises to assess whether dominant planktonic microorganisms use visible sunlight to enhance uptake of these organic molecules at ambient concentrations. The two numerically dominant groups of oceanic bacterioplankton were Prochlorococcus cyanobacteria and bacteria with low nucleic acid (LNA) content, comprising 60% SAR11-related cells. The results of flow cytometric sorting of labelled bacterioplankton cells showed that when incubated in the light, Prochlorococcus and LNA bacteria increased their uptake of amino acids on average by 50% and 23%, respectively, compared with those incubated in the dark. Amino acid uptake of Synechococcus cyanobacteria was also enhanced by visible light, but bacteria with high nucleic acid content showed no light stimulation. Additionally, differential uptake of the two amino acids by the Prochlorococcus and LNA cells was observed. The populations of these two types of cells on average completely accounted for the determined 22% light enhancement of amino acid uptake by the total bacterioplankton community, suggesting a plausible way of harnessing light energy for selectively transporting scarce nutrients that could explain the numerical dominance of these groups in situ.

Perspectives and Integration in SOLAS Science

Why a chapter on Perspectives and Integration in SOLAS Science in this book? SOLAS science by its nature deals with interactions that occur: across a wide spectrum of time and space scales, involve gases and particles, between the ocean and the atmosphere, across many disciplines including chemistry, biology, optics, physics, mathematics, computing, socio-economics and consequently interactions between many different scientists and across scientific generations. This chapter provides a guide through the remarkable diversity of cross-cutting approaches and tools in the gigantic puzzle of the SOLAS realm. Here we overview the existing prime components of atmospheric and oceanic observing systems, with the acquisition of ocean–atmosphere observables either from in situ or from satellites, the rich hierarchy of models to test our knowledge of Earth System functioning, and the tremendous efforts accomplished over the last decade within the COST Action 735 and SOLAS Integration project frameworks to understand, as best we can, the current physical and biogeochemical state of the atmosphere and ocean commons. A few SOLAS integrative studies illustrate the full meaning of interactions, paving the way for even tighter connections between thematic fields. Ultimately, SOLAS research will also develop with an enhanced consideration of societal demand while preserving fundamental research coherency.

Diverse profiles of N‐acyl‐homoserine lactone molecules found in cnidarians

Many marine habitats, such as the surface and tissues of marine invertebrates, including corals, harbour diverse populations of microorganisms, which are thought to play a role in the health of their hosts and influence mutualistic and competitive interactions. Investigating the presence and stability of quorum sensing (QS) in these ecosystems may shed light on the roles and control of these bacterial communities. Samples of 13 cnidarian species were screened for the presence and diversity of N-acyl-homoserine lactones (AHLs; a prevalent type of QS molecule) using thin-layer chromatography and an Agrobacterium tumefaciens NTL4 biosensor. Ten of 13 were found to harbour species-specific, conserved AHL profiles. AHLs were confirmed in Anemonia viridis using liquid chromatography tandem mass spectrometry. To assess temporal role and stability, AHLs were investigated in A. viridis from intertidal pools over 16 h. Patterns of AHLs showed conserved profiles except for two mid-chain length AHLs, which increased significantly over the day, peaking at 20:00, but had no correlation with pool chemistry. Denaturing gel electrophoresis of RT-PCR-amplified bacterial 16S rRNA showed the presence of an active bacterial community that changed in composition alongside AHL profiles and contained a number of bands that affiliate with known AHL-producing bacteria. Investigations into the quorum sensing-controlled, species-specific roles of these bacterial communities and how these regulatory circuits are influenced by the coral host and members of the bacterial community are imperative to expand our knowledge of these interactions with respect to the maintenance of coral health.

Disturbance to conserved bacterial communities in the cold water gorgonian coral Eunicella verrucosa

The bacterial communities associated with healthy and diseased colonies of the cold-water gorgonian coral Eunicella verrucosa at three sites off the south-west coast of England were compared using denaturing gradient gel electrophoresis (DGGE) and clone libraries. Significant differences in community structure between healthy and diseased samples were discovered, as were differences in the level of disturbance to these communities at each site; this correlated with depth and sediment load. The majority of cloned sequences from healthy coral tissue affiliated with the Gammaproteobacteria. The stability of the bacterial community and dominance of specific genera found across visibly healthy colonies suggest the presence of a specific microbial community. Affiliations included a high proportion of Endozoicomonas sequences, which were most similar to sequences found in tropical corals. This genus has been found in a number of invertebrates and is suggested to have a role in coral health and in the metabolisation of dimethylsulfoniopropionate (DMSP) produced by zooxanthellae. However, screening of colonies for the presence of zooxanthellae produced a negative result. Diseased colonies showed a decrease in affiliated clones and an increase in clones related to potentially harmful/transient microorganisms but no increase in a particular pathogen. This study demonstrates that a better understanding of these bacterial communities, the factors that affect them and their role in coral health and disease will be of critical importance in predicting future threats to temperate gorgonian communities.

Validation of the detection of Pseudo-nitzschia spp. using specific RNA probes tested in a microarray format: Calibration of signal based on variability of RNA content with environmental conditions.

Harmful algal blooms (HAB) occur worldwide and cause health problems and economic damage to fisheries and tourism. Monitoring for toxic algae is therefore essential but is based primarily on light microscopy, which is time consuming and can be limited by insufficient morphological characters such that more time is needed to examine critical features with electron microscopy. Monitoring with molecular tools is done in only a few places world-wide. EU FP7 MIDTAL (Microarray Detection of Toxic Algae) used SSU and LSU rRNA genes as targets on microarrays to identify toxic species. In order to comply with current monitoring requirements to report cell numbers as the relevant threshold measurement to trigger closure of fisheries, it was necessary to calibrate our microarray to convert the hybridisation signal obtained to cell numbers. Calibration curves for two species of Pseudo-nitzschia for use with the MIDTAL microarray are presented to obtain cell numbers following hybridisation. It complements work presented by Barra et al. (2012b. Environ. Sci. Pollut. Res. doi: 10.1007/s11356-012-1330-1v) for two other Pseudo-nitzschia spp., Dittami and Edvardsen (2012a. J. Phycol. 48, 1050) for Pseudochatonella, Blanco et al. (2013. Harmful Algae 24, 80) for Heterosigma, McCoy et al. (2013. FEMS. doi: 10.1111/1574-6941.12277) for Prymnesium spp., Karlodinium veneficum, and cf. Chatonella spp. and Taylor et al. (2014. Harmful Algae, in press) for Alexandrium.

The Unexpected Preference for the fac-Isomer with the Tris(5-ester-substituted-2,2′-bipyridine) Complexes of Ruthenium(II)

The synthesis of a number of new 2,2'-bipyridine ligands, functionalized with bulky ester side groups is reported (L2 - L8). Their reaction with [Ru(DMSO)4Cl2] gives rise to tris-chelate ruthenium(II) metal complexes which show an unusually high proportion of the fac-isomer, as judged by 1H NMR following conversion to the ruthenium(II) complex of 2,2'-bipyridine-5-carboxylic acid methyl ester (L1). The initial reaction appears to have thermodynamic control with the steric bulk of the ligands causing the third ligand to be labile under the reaction conditions used, giving rise to disappointing yields and allowing rearrangement to the more stable facial form. DFT studies indicate that this does not appear to be as a consequence of a metal centered electronic effect. The two isomers of [Ru(L1)3](PF6)2 were separated into the two individual forms using silica preparative plate chromatographic procedures, and the photophysical characteristics of the two forms compared. The results appear to indicate that there is no significant difference in both their room temperature electronic absorption and emission spectra or their excited state lifetimes at 77K.

Enantiocomplementary preparation of (S)- and (R)-1-pyridylalkanols via ketone reduction and alkane hydroxylation using whole cells of Pseudomonas putida UV4

A previously unreported alcohol dehydrogenase enzyme in the mutant soil bacterium Pseudomonas putida UV4 catalyses the reduction of 2-, 3- and 4-acylpyridines to afford the corresponding (S)-1-pyridyl alkanols, with moderate to high e.e., whilst under the same conditions 2,6-diacetylpyridine is readily converted to the corresponding enantiopure C2-symmetric (S,S)-diol in one step. In contrast, the toluene dioxygenase enzyme in the same organism catalyses the hydroxylation of 2- and 3-alkylpyridines to (R)-1-(2-pyridyl) and (R)-1-(3-pyridyl)alkanols. This combination of oxidative and reductive biotransformations thus provides a method for preparing both enantiomers of chiral 1-pyridyl alkanols using one biocatalyst.