Coccolithophore Relief: An Art and Science Interrogation of Ocean Acidification

Organisms that remove carbon from the world’s carbon cycle are becoming ever more important as we try to constrain our carbon emissions to slow climate change. Marine phytoplankton, like coccolithophores, are responsible for 50 percent of global carbon fixation. Through photosynthesis, which also produces oxygen as a by-product, they fix carbon dioxide throughout their lives in the surface waters of the ocean. Even in their death, they help remove carbon from the system. Coccolithophores make armoured plates (coccoliths, hereafter referred to as ‘liths’) from calcium carbonate, which together form a sort of external skeleton for each organism. When they die, they sink and join bottom sediments, in effect exporting and burying carbon in deep-sea sediments.We decided to share the story of coccolithophores, including their important environmental role and their sensitivity to ocean acidification, with the public. We intentionally developed a project involving social arts practice to help people reflect on the importance of these small things. This included the beauty of the tiny liths that make up the  coccolithophore’s amour, the importance of each little lith to collectively make a healthy organism (that in turn has an important global role), and the effect of our individual small actions contributing to climate change. Engaging communities in social arts practice, by involving hands-on making with cognitive activity, gives time and space for such criticalreflection.5 Joining key features of the scientific narrative with congruent aspects of the art-making can serve to reinforce understanding and potential behaviour change

Marine microbial community dynamics and responses to ocean acidification

Marine microbes, including both eukaryotes and prokaryotes, are the basal components of marine food webs and play a fundamental role in global biogeochemical cycling. Marine phytoplankton are responsible for approximately 50% of Earth’s primary production, while heterotrophic bacteria and archaea modulate carbon and nutrient cycling in the marine environment. The structure and function of marine microbial communities are closely coupled. Consequently, understanding the factors which govern the distribution of marine microbes through space and time has key implications for food webs and biogeochemical cycling. The development of high-throughput sequencing technologies has revolutionised marine microbial ecology by facilitating the profiling of microbial communities in high taxonomic resolution. In this thesis high-throughput sequencing of the 16S and 18S rRNA genes was used to achieve two major aims. The first aim was to investigate the ecological processes which underpin microbial community assembly in the marine environment. The second aim was to investigate the responses of marine microbial communities to near- future ocean acidification. Two studies were performed towards the first aim of this thesis. In the first study, the microbial biogeography of the South Pacific Gyre was characterised across three depths at 22 stations along a 2,000 km longitudinal transect of the region. Microbial community composition was homogenous across horizontal spatial scales in the surface waters of the South Pacific Gyre, but varied significantly between surface waters and the deep chlorophyll maximum. A null model approach was used to unveil the ecological processes driving microbial community assembly in the region. Microbial communities in the surface waters were assembled primarily through the deterministic process of homogeneous selection, indicating that selection pressures were sufficient to overwhelm the influence of dispersal effects and ecological drift across vast horizontal spatial distances in the region. Dispersal limitation was comparatively more influential in the assembly of microbial communities between the surface waters and the deep chlorophyll maximum, indicating that stochastic processes play a significant role in microbial community assembly between these contiguous water masses. In the second study, the bacterioplankton and protist biogeography of the Southland Front system was characterised in surface waters at 24 stations spanning four water masses. Both bacterioplankton and protist communities displayed significant structuring according to water mass, although this effect was most pronounced in bacterioplankton communities. A null model approach revealed that bacterioplankton communities were primarily assembled through homogeneous selection, while protist communities were primarily assembled through dispersal limitation and ecological drift across the Southland Front system. These findings highlight that distinct ecological processes can underpin the assembly of co- occurring bacterioplankton and protist communities, and that hydrographic features such as oceanic fronts play an important role in structuring both bacterioplankton and protist communities. Two studies were conducted towards the second aim of this thesis. In the first study, the effect of ocean acidification and warming on bacterioplankton communities was investigated at the fringe and ultra-oligotrophic centre of the South Pacific Gyre using trace-metal clean deckboard incubation experiments. Bacterioplankton community composition and function were resistant to ocean acidification alone, and combined with warming, at the fringe of the South Pacific Gyre. Subtle but significant responses of bacterioplankton community composition to ocean acidification were observed at the ultra- oligotrophic centre of the South Pacific Gyre. These results suggest that bacterioplankton community responses to ocean acidification may be modulated by nutrient regimes. Nonetheless, the findings of this study did not diverge substantially from the narrative that bacterioplankton communities are resistant to near-future acidification. In the second study, the effect of ocean acidification on both prokaryotic and eukaryotic biofilm communities was investigated at the Shikine-Jima CO2 seep system in Japan. The composition of both prokaryotic and eukaryotic communities was profoundly affected by ocean acidification through early successional stages, though these responses were not associated with shifts in community diversity or evenness. Notably, the relative abundance of the nuisance algae Prymnesium sp. and Biddulphia biddulphiana were enhanced under high CO2 conditions. These findings suggest that benthic biofilm communities may be vulnerable to near-future ocean acidification, and that changes in biofilm community composition may contribute to the reorganisation of coastal ecosystem observed at CO2 seeps globally. In its entirety, this thesis significantly contributes to our understanding of the spatial dynamics of marine microbial communities by revealing the highly deterministic nature of bacterioplankton community assembly in the coastal waters and central gyre of the South Pacific Ocean. Furthermore, the findings of this thesis highlight the dominance of stochastic processes in structuring marine protist communities across short spatial scales, which may contribute to challenges in correlating abiotic environmental variables with marine protist community composition through space. The resistance of bacterioplankton communities to ocean acidification at the fringe of the South Pacific Gyre, and subtle responses to ocean acidification at the ultra-oligotrophic centre of the South Pacific Gyre broadly support the notion that bacterioplankton communities are resilient to near-future ocean acidification. In contrast, the composition of both prokaryotic and eukaryotic biofilm communities was profoundly affected by ocean acidification, leading to the proliferation of harmful algae with potentially severe consequences for coastal marine environments

Airway resistance at maximum inhalation as a marker of asthma and airway hyperresponsiveness

<p>Abstract</p> <p>Background</p> <p>Asthmatics exhibit reduced airway dilation at maximal inspiration, likely due to structural differences in airway walls and/or functional differences in airway smooth muscle, factors that may also increase airway responsiveness to bronchoconstricting stimuli. The goal of this study was to test the hypothesis that the minimal airway resistance achievable during a maximal inspiration (R_min) is abnormally elevated in subjects with airway hyperresponsiveness.</p> <p>Methods</p> <p>The R_minwas measured in 34 nonasthmatic and 35 asthmatic subjects using forced oscillations at 8 Hz. R_minand spirometric indices were measured before and after bronchodilation (albuterol) and bronchoconstriction (methacholine). A preliminary study of 84 healthy subjects first established height dependence of baseline R_minvalues.</p> <p>Results</p> <p>Asthmatics had a higher baseline R_min% predicted than nonasthmatic subjects (134 ± 33 vs. 109 ± 19 % predicted, p = 0.0004). Sensitivity-specificity analysis using receiver operating characteristic curves indicated that baseline R_minwas able to identify subjects with airway hyperresponsiveness (PC₂₀< 16 mg/mL) better than most spirometric indices (Area under curve = 0.85, 0.78, and 0.87 for R_min% predicted, FEV₁% predicted, and FEF_25-75% predicted, respectively). Also, 80% of the subjects with baseline R_min< 100% predicted did not have airway hyperresponsiveness while 100% of subjects with R_min> 145% predicted had hyperresponsive airways, regardless of clinical classification as asthmatic or nonasthmatic.</p> <p>Conclusions</p> <p>These findings suggest that baseline R_min, a measurement that is easier to perform than spirometry, performs as well as or better than standard spirometric indices in distinguishing subjects with airway hyperresponsiveness from those without hyperresponsive airways. The relationship of baseline R_minto asthma and airway hyperresponsiveness likely reflects a causal relation between conditions that stiffen airway walls and hyperresponsiveness. In conjunction with symptom history, R_mincould provide a clinically useful tool for assessing asthma and monitoring response to treatment.</p

Imaging of Flow Patterns with Fluorescent Molecular Rotors

Molecular rotors are a group of fluorescent molecules that form twisted intramolecular charge transfer states (TICT) upon photoexcitation. Some classes of molecular rotors, among them those that are built on the benzylidene malononitrile motif, return to the ground state either by nonradiative intramolecular rotation or by fluorescence emission. In low-viscosity solvents, intramolecular rotation dominates, and the fluorescence quantum yield is low. Higher solvent viscosities reduce the intramolecular rotation rate, thus increasing the quantum yield. We recently described a different mechanism whereby the fluorescence quantum yield of the molecular rotor also depends on the shear stress of the solvent. In this study, we examined a possible application for shear-sensitive molecular rotors for imaging flow patterns in fluidic chambers. Flow chambers with different geometries were constructed from polycarbonate or acrylic. Solutions of molecular rotors in ethylene glycol were injected into the chamber under controlled flow rates. LED-induced fluorescence (LIF) images of the flow chambers were taken with a digital camera, and the intensity difference between flow and no-flow images was visualized and compared to computed fluid dynamics (CFD) simulations. Intensity differences were detectable with average flow rates as low as 0.1 mm/s, and an exponential association between flow rate and intensity increase was found. Furthermore, a good qualitative match to computed fluid dynamics simulations was seen. On the other hand, prolonged exposure to light reduced the emission intensity. With its high sensitivity and high spatial and temporal resolution, imaging of flow patterns with molecular rotors may become a useful tool in microfluidics, flow measurement, and control

Latitudinal variation in the potential activity of Atlantic Ocean bacterioplankton revealed through 16S rRNA and 16S rRNA gene metabarcoding

The activities of bacterioplankton sustain open ocean biogeochemical and ecological processes, however, little is known about the activity of specific bacterioplankton, especially related to their biogeography across oceanic scales. The Atlantic is the second largest of the world’s oceans and has an essential role in the global carbon cycle. Here, we show congruence in the structure of 16S rRNA and 16S rRNA gene derived bacterioplankton communities throughout the Atlantic Ocean from temperate to tropical regions. We used 16S rRNA:16S rRNA gene ratios as a phylogenetically resolved proxy for potential activity, demonstrating ocean-scale patterns of putative oligotrophy and copiotrophy in major bacterioplankton groups, with spatial niche partitioning being evident at single-nucleotide resolution within some groups, including the Flavobacteria and SAR86. This study examines the potential structure of the active microbiome of the Atlantic Ocean, providing novel insights into the ecology and life history strategies of both well-known and currently understudied bacterioplankton taxa

Mechanisms of Psychological Distress following War in the Former Yugoslavia: The Role of Interpersonal Sensitivity

This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.This study was funded by a grant from the European Commission, contract number INCO-CT-2004-509176. AN was supported by a Clinical Early Career Research Fellowship (113295) and a Project Grant (104288

Testing the cognitive-behavioural maintenance models across DSM-5 bulimic-type eating disorder diagnostic groups: A multi-centre study

The original cognitive-behavioural (CB) model of bulimia nervosa, which provided the basis for the widely used CB therapy, proposed that specific dysfunctional cognitions and behaviours maintain the disorder. However, amongst treatment completers, only 40–50 % have a full and lasting response. The enhanced CB model (CB-E), upon which the enhanced version of the CB treatment was based, extended the original approach by including four additional maintenance factors. This study evaluated and compared both CB models in a large clinical treatment seeking sample (N = 679), applying both DSM-IV and DSM-5 criteria for bulimic-type eating disorders. Application of the DSM-5 criteria reduced the number of cases of DSM-IV bulimic-type eating disorders not otherwise specified to 29.6 %. Structural equation modelling analysis indicated that (a) although both models provided a good fit to the data, the CB-E model accounted for a greater proportion of variance in eating-disordered behaviours than the original one, (b) interpersonal problems, clinical perfectionism and low self-esteem were indirectly associated with dietary restraint through over-evaluation of shape and weight, (c) interpersonal problems and mood intolerance were directly linked to binge eating, whereas restraint only indirectly affected binge eating through mood intolerance, suggesting that factors other than restraint may play a more critical role in the maintenance of binge eating. In terms of strength of the associations, differences across DSM-5 bulimic-type eating disorder diagnostic groups were not observed. The results are discussed with reference to theory and research, including neurobiological findings and recent hypotheses

Production of benzylisoquinoline alkaloids in Saccharomyces cerevisiae

The benzylisoquinoline alkaloids (BIAs) are a diverse class of metabolites that exhibit a broad range of pharmacological activities and are synthesized through plant biosynthetic pathways comprised of complex enzyme activities and regulatory strategies. We have engineered yeast to produce the key intermediate reticuline and downstream BIA metabolites from a commercially available substrate. An enzyme tuning strategy was implemented that identified activity differences between variants from different plants and determined optimal expression levels. By synthesizing both stereoisomer forms of reticuline and integrating enzyme activities from three plant sources and humans, we demonstrated the synthesis of metabolites in the sanguinarine/berberine and morphinan branches. We also demonstrated that a human P450 enzyme exhibits a novel activity in the conversion of (R)-reticuline to the morphinan alkaloid salutaridine. Our engineered microbial hosts offer access to a rich group of BIA molecules and associated activities that will be further expanded through synthetic chemistry and biology approaches

Frontal Non-Invasive Neurostimulation Modulates Antisaccade Preparation in Non-Human Primates

A combination of oculometric measurements, invasive electrophysiological recordings and microstimulation have proven instrumental to study the role of the Frontal Eye Field (FEF) in saccadic activity. We hereby gauged the ability of a non-invasive neurostimulation technology, Transcranial Magnetic Stimulation (TMS), to causally interfere with frontal activity in two macaque rhesus monkeys trained to perform a saccadic antisaccade task. We show that online single pulse TMS significantly modulated antisaccade latencies. Such effects proved dependent on TMS site (effects on FEF but not on an actively stimulated control site), TMS modality (present under active but not sham TMS on the FEF area), TMS intensity (intensities of at least 40% of the TMS machine maximal output required), TMS timing (more robust for pulses delivered at 150 ms than at 100 post target onset) and visual hemifield (relative latency decreases mainly for ipsilateral AS). Our results demonstrate the feasibility of using TMS to causally modulate antisaccade-associated computations in the non-human primate brain and support the use of this approach in monkeys to study brain function and its non-invasive neuromodulation for exploratory and therapeutic purposes