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Key Points: Synoptic‐scale winter blooms and mixed‐layer pump events were observed by a BGC‐Argo float in the midlatitude Northwest Pacific OceanThe repetitive mixed‐layer pump episodes generated a very high particulate organic carbon export of ~110 mg C m−2 day−1 in wintertimeThe current BGC‐Argo protocols captured only 20%, or entirely missed, substantial pulsed carbon export driven by mixed‐layer pump events The winter‐ and spring‐time mixed‐layer pump (MLP) significantly augments the global carbon transport from the surface mixed layer to deeper waters when ephemeral surface phytoplankton blooms are repeatedly mixed to depth. Exploiting unusual 190 + daily BGC‐Argo profiling measurements within a recirculation gyre, we show repetitive MLP episodes generating a January–March averaged particulate organic carbon (POC) export of ~110 mg C m−2 day−1 in the midlatitude (31°N) Northwest Pacific. Subsampling this dataset on a 5‐ or 10‐day cycle yielded an order of magnitude less export, or even totally missed all the MLP events. The evidence here supports the need for new strategies if the BGC‐Argo program is to adequately quantify ocean carbon cycling and its effects on biological systems. We propose that a handful of floats be tasked with daily profiling, and machine learning strategies be used to link these data with satellite derived measurements to estimate the synoptic‐scale MLP export. Plain Language Summary: The Biogeochemical‐Argo program (BGC‐Argo) is an essential tool for quantifying carbon export from surface waters to the ocean interior, which is critical for understanding and forecasting changes in atmospheric CO2. Using novel, high‐frequency (1‐day cycle during 9‐ month period) BGC‐Argo data, we estimated the carbon export in the midlatitude Northwest Pacific Ocean stemming from unexpectedly continuous mixed‐layer pump (MLP) events. Such events occur when wintertime phytoplankton blooms developed during calm wind periods then are injected to depth by storms. This process generated remarkably high carbon export over winter, with values ranging from 18% to 30% of that from the massive North Atlantic spring bloom. These events, however, are largely (80%) or entirely missed using the longer standard float cycling intervals (5–10 days) accepted by the BGC‐Argo program. The findings here suggest that some high‐frequency BGC‐Argo observations are necessary for more accurately estimating the global carbon export. [ABSTRACT FROM AUTHOR]

Here are two widely held positions on the ethics of dating: First, people are generally morally justified in excluding people they don't find attractive from their dating pool. Second, people are not justified in maintaining a dating pool that is racially exclusive, even on grounds like attraction. In this paper, we demonstrate how these positions are consistent. To do so we differentiate our attitudes in dating and our dating behavior. Then we show how existing criticisms of racialized attitudes in dating are incomplete as practical criticisms of our behavior. Finally, we give our account of the moral reasons whites have to change their dating preferences when they exclude people of color. In doing so, we supplement existing discussions of race-based discrimination in dating. [ABSTRACT FROM AUTHOR]

Global demand for macroalgal and microalgal foods is growing, and algae are increasingly being consumed for functional benefits beyond the traditional considerations of nutrition and health. There is substantial evidence for the health benefits of algal-derived food products, but there remain considerable challenges in quantifying these benefits, as well as possible adverse effects. First, there is a limited understanding of nutritional composition across algal species, geographical regions, and seasons, all of which can substantially affect their dietary value. The second issue is quantifying which fractions of algal foods are bioavailable to humans, and which factors influence how food constituents are released, ranging from food preparation through genetic differentiation in the gut microbiome. Third is understanding how algal nutritional and functional constituents interact in human metabolism. Superimposed considerations are the effects of harvesting, storage, and food processing techniques that can dramatically influence the potential nutritive value of algal-derived foods. We highlight this rapidly advancing area of algal science with a particular focus on the key research required to assess better the health benefits of an alga or algal product. There are rich opportunities for phycologists in this emerging field, requiring exciting new experimental and collaborative approaches. [ABSTRACT FROM AUTHOR]

Climate change pressures will influence marine planktonic systems globally, and it is conceivable that harmful algal blooms may increase in frequency and severity. These pressures will be manifest as alterations in temperature, stratification, light, ocean acidification, precipitation-induced nutrient inputs, and grazing, but absence of fundamental knowledge of the mechanisms driving harmful algal blooms frustrates most hope of forecasting their future prevalence. Summarized here is the consensus of a recent workshop held to address what currently is known and not known about the environmental conditions that favor initiation and maintenance of harmful algal blooms. There is expectation that harmful algal bloom (HAB) geographical domains should expand in some cases, as will seasonal windows of opportunity for harmful algal blooms at higher latitudes. Nonetheless there is only basic information to speculate upon which regions or habitats HAB species may be the most resilient or susceptible. Moreover, current research strategies are not well suited to inform these fundamental linkages. There is a critical absence of tenable hypotheses for how climate pressures mechanistically affect HAB species, and the lack of uniform experimental protocols limits the quantitative cross-investigation comparisons essential to advancement. A HAB “best practices” manual would help foster more uniform research strategies and protocols, and selection of a small target list of model HAB species or isolates for study would greatly promote the accumulation of knowledge. Despite the need to focus on keystone species, more studies need to address strain variability within species, their responses under multifactorial conditions, and the retrospective analyses of long-term plankton and cyst core data; research topics that are departures from the norm. Examples of some fundamental unknowns include how larger and more frequent extreme weather events may break down natural biogeographic barriers, how stratification may enhance or diminish HAB events, how trace nutrients (metals, vitamins) influence cell toxicity, and how grazing pressures may leverage, or mitigate HAB development. There is an absence of high quality time-series data in most regions currently experiencing HAB outbreaks, and little if any data from regions expected to develop HAB events in the future. A subset of observer sites is recommended to help develop stronger linkages among global, national, and regional climate change and HAB observation programs, providing fundamental datasets for investigating global changes in the prevalence of harmful algal blooms. Forecasting changes in HAB patterns over the next few decades will depend critically upon considering harmful algal blooms within the competitive context of plankton communities, and linking these insights to ecosystem, oceanographic and climate models. From a broader perspective, the nexus of HAB science and the social sciences of harmful algal blooms is inadequate and prevents quantitative assessment of impacts of future HAB changes on human well-being. These and other fundamental changes in HAB research will be necessary if HAB science is to obtain compelling evidence that climate change has caused alterations in HAB distributions, prevalence or character, and to develop the theoretical, experimental, and empirical evidence explaining the mechanisms underpinning these ecological shifts. [ABSTRACT FROM AUTHOR]

The author discusses aspects of the relationship of Native American intertribal warfare across the U.S. He examines the establishment of the national defense through the modern air forces with the members of individual tribes. The author highlights the hierarchical organization of any military member ranks as well as the outcomes of the conflict among the American Indian tribes.

Aggregation of metal oxide nanoparticles in aqueous media complicates interpretation of in vitro studies of nanoparticle-cell interactions. We used dynamic light scattering to investigate the aggregation dynamics of iron oxide and zinc oxide nanoparticles. Our results show that iron oxide particles aggregate more readily than zinc oxide particles. Pretreatment with serum stabilises iron oxide and zinc oxide nanoparticles against aggregation. Serum-treated iron oxide is stable only in pure water, while zinc oxide is stable in water or cell culture media. These findings, combined with zeta potential measurements and quantification of proteins adsorbed on particle surface, suggest that serum stabilisation of iron oxide particles occurs primarily through protein adsorption and resulting net surface charge. Zinc oxide stabilisation, however, also involves steric hindrance of particle aggregation. Fluid shear at levels used in flow experiments breaks up iron oxide particle aggregates. These results enhance our understanding of nanoparticle aggregation and its consequences for research on the biological effects of nanomaterials. [ABSTRACT FROM AUTHOR]

Abstract: Redox cycling of iron in natural seawater is an important process that can affect iron availability to marine phytoplankton. In this work, luminol chemiluminescence was used to measure picomolar Fe(II) oxidation rate constants in continental shelf waters and oceanic surface (upper 200m) waters of the iron-limited eastern subarctic Pacific. In both cases, Fe(II) oxidation rate constants were faster within the chlorophyll maximum than in UV oxidized seawater (UVOS), while rate constants were comparable to UVOS rate constants in waters from below the mixed layer. The larger Fe(II) oxidation rate constants in surface waters converged with UVOS rate constants upon stepwise additions of either Fe(II) or Fe(III), while Fe titrations did not affect Fe(II) oxidation rate constants in waters from below the mixed layer. Direct measurements of hydrogen peroxide, a common Fe(II) oxidant in surface waters, do not explain the high Fe(II) oxidation rate constants. We hypothesize that excess concentrations of strong Fe(III)-complexing organic ligands measured in surface seawater increase Fe(II) oxidation, and that titration of these ligands with added Fe explains the observed slowing of Fe(II ) oxidation rates. Given that Fe(III)-complexing ligands are found in both surface and deep waters, and higher Fe(II) oxidation rate constants were measured only near the chlorophyll maximum, we suggest that the chemical nature and perhaps origin of natural Fe(III)-complexing organic ligands differ between in surface and deep waters. [Copyright &y& Elsevier]

Abstract: Biotechnology is a promising approach for the generation of hydrogen, but is not yet commercially viable. Metabolic engineering is a potential solution, but has largely been limited to native pathway optimisation. To widen opportunities for use of non-native [NiFe] hydrogenases for improved hydrogen production, we introduced a cyanobacterial hydrogen production pathway and associated maturation factors into Escherichia coli. Hydrogen production is observed in vivo in a hydrogenase null host, demonstrating coupling to host electron transfer systems. Hydrogenase activity is also detected in vitro. Hydrogen output is increased when formate production is abolished, showing that the new pathway is distinct from the native formate dependent pathway and supporting the conclusion that it couples cellular NADH and NADPH pools to molecular hydrogen. This work demonstrates non-native hydrogen production in E. coli, showing the wide portability of [NiFe] hydrogenase pathways and the potential for metabolic engineering to improve hydrogen yields. [Copyright &y& Elsevier]

Abstract: Dissolved iron profiles along a north–south transect along 158°W in the tropical Pacific show evidence of two deepwater anomalies. The first extends from Station ALOHA (22.78°N) to the equator at ∼1000–1500m and lies below the maximum apparent oxygen utilization and nutrient (N, P) concentrations. The feature is not supported by vertical export processes, but instead corresponds with the lateral dilution field of δ3He derived from the Loihi seamount, Hawaii, though a sediment source associated with the Hawaiian Island Chain cannot be entirely ruled out. The second, deeper (2000–3000m) anomaly occurs in tropical South Pacific waters (7°S) and also does not correlate with the depths of maximum nutrient concentrations or apparent oxygen utilization, but it does coincide closely with δ3He emanating from the East Pacific Rise, more than 5000km to the east. We hypothesize that these anomalies represent the long-range (>2000km) transport of hydrothermal iron residuals, stabilized against scavenging by complexation with excess organic ligands in the plume source regions. Such trace leakage of hydrothermal iron to distal plume regions would have been difficult to identify in most hydrothermal vent mapping studies because low analytical detection limits were not needed for the proximal plume regions. These findings suggest that hydrothermal activity may represent a major source of dissolved iron throughout the South Pacific deep basin today, as well as other regions having high mid-ocean spreading rates in the geologic past. In particular, we hypothesize that high spreading rates along the South Atlantic and Southern Ocean mid-oceanic ridges, combined with the upwelling ventilation of these distal hydrothermal plumes, may have increased ocean productivity and carbon export in the Southern Ocean. Assessing the magnitude and persistence of dissolved hydrothermal iron in basin scale deep waters will be important for understanding the marine biogeochemistry of iron and, potentially, on ocean productivity and climate change during the geologic past. [Copyright &y& Elsevier]

Abstract: The cumulative evidence from more than a dozen mesoscale iron-enrichment studies in high nitrate low chlorophyll (HNLC) waters demonstrates that iron limitation is widespread and very likely affects atmospheric carbon dioxide and thus global climate. However, the responses of microphytoplankton (>20μm), predominantly diatoms, vary greatly among these mesoscale experiments even though similar amounts of iron were added, making it difficult to quantitatively incorporate iron effects into global climate models. Nowhere is this difference more dramatic than between the massive bloom observed during Subarctic Pacific Iron Experiment for Ecosystem Dynamics Study (SEEDS) I and the order of magnitude smaller ecosystem response in SEEDS II; two mesocale experiments performed in the same HNLC region of the western subarctic Pacific in different years. Deckboard incubation experiments initiated during the early, middle, and late stages of the 32-day SEEDS II experiment show that while the two iron infusions increased phytoplankton growth, diatoms remained significantly limited by iron availability, despite total dissolved Fe concentrations in the patch being well above the diffusion-limited threshold for rapid diatom growth. This iron limitation was apparent <6 days after the initial iron infusion and was not alleviated by the second, smaller iron infusion. In contrast, smaller phytoplankton (<20μm) showed a more restricted response to further iron amendments, indicating that their iron nutrition was near optimal. Iron complexed to desferrioximine B, a commonly available siderophore produced by at least one marine bacterium, was poorly available to diatoms throughout the patch evolution, indicating that these diatoms lacked the ability to induce high-affinity iron uptake systems. These results suggest that the strong organic complexation of Fe(III) observed in the SEEDS II-fertilized patch was not compatible with rapid diatom growth. In contrast, iron associated with protoporphyrin IX, a weaker iron complexing ligand of a class hypothesized to be representative of recycled iron species, was readily available to diatoms. Our findings demonstrate that a persistence of iron limitation was the primary factor underlying the comparatively small diatom response during SEEDS II. This continued growth limitation would have increased the importance of mesozooplankton grazing as a controlling factor in the SEEDS II ecosystem response. [Copyright &y& Elsevier]

Proteins with intrinsically disordered domains are implicated in a vast range of biological processes, especially in cell signaling and regulation. Having solved the quaternary structure of the folded domains in the tumor suppressor p53 by a multidisciplinary approach, we have now determined the average ensemble structure of the intrinsically disordered N-terminal transactivation domain (TAD) by using residual dipolar couplings (RDCs) from NMR spectroscopy and small-angle x-ray scattering (SAXS). Remarkably, not only were we able to measure RDC5 of the isolated TAD, but we were also able to do so for the TAD in both the full-length tetrameric p53 protein and in its complex with a specific DNA response element. We determined the orientation of the TAD ensemble relative to the core domain, found that the TAD was stiffer in the proline-rich region (residues 64-92), which has a tendency to adopt a polyproline II (PPll) structure, and projected the TAD away from the core. We located the TAD in SAXS experiments on a complex between tetrameric p53 and four Taz2 domains that bind tightly to the TAD (residues 1-57) and acted as "reporters." The p53-Taz2 complex was an extended cross-shaped structure. The quality of the SAXS data enabled us to model the disordered termini and the folded domains in the complex with DNA. The core domains enveloped the response element in the center of the molecule, with the Taz2-bound TAD5 projecting outward from the core. [ABSTRACT FROM AUTHOR]

Abstract: Marine chromophoric dissolved organic matter (CDOM) imparts highly variable optical signatures in surface waters over short spatial and temporal scales, but the cause of that variability is poorly understood. A major fraction of dissolved organic matter in seawater is colloidal in size and can cycle quite rapidly, potentially contributing to the observed variability in CDOM. The relationship between marine colloids and CDOM optical variability was examined using flow field-flow fractionation (FlFFF) to partition the colloidal organic phase into a continuum of molecular sizes for optical characterization by excitation emission matrix spectroscopy (EEMS). Colloidal organic matter in surface seawater of the Damariscotta River estuary showed 2 major peaks in apparent abundance, spanning at ∼1–5 kDa and ∼15–150 kDa in size, respectively. The relative magnitude of these peaks changed systematically with the phase of phytoplankton blooms during 2003 and 2004, implying a relationship between colloid size distribution and bloom dynamics. Of the two colloidal sizes, the 1–5 kDa fraction was far more variable in apparent abundance than the larger colloidal matter. EEMS results reveal a compositional partitioning of protein-like and humic-like fluorescence between size fractions. Protein-like materials occurred primarily in the smallest colloid size fraction while humic-type materials resided mainly in the larger colloidal phase. These findings suggest that the fluorescence signature of bulk dissolved organic matter results from a collage of chromophores having optical characteristics that differ according to size of the molecular constituents. The colloidal-sized fluorescence characteristics of marine derived CDOM were contrasted with bulk CDOM to provide fundamental information on the distribution and forms of CDOM in Maine coastal waters. The findings here indicate that colloidal processes will have significant effects on the character and variability in the optical signature of surface seawaters. [Copyright &y& Elsevier]

The role of conformational intermediates in the conversion of prion protein from its normal cellular form (PrPC) to the disease-associated "scrapie" form (PrPSc) remains unknown. To look for such intermediates in equilibrium conditions, we have examined the unfolding transitions of PrPC, primarily using the chemical denaturant guanidine hydrochloride (GuHCl). When the protein conformation is assessed by NMR, there is a gradual shift of NMR signals in the regions between residues 125-146 and 186-196. The denaturant dependence of these shifts shows that in aqueous solution the native and locally unfolded conformations are both significantly populated. Following this shift, there is the major unfolding transition to generate a substantially unfolded population. However, analysis of NMR chemical shift and intensity changes shows that there is persistent structure in the molecule well beyond this major cooperative unfolding transition. Residual structure within this state is extensive and encompasses the majority of the secondary structure elements found in the native state of the protein. [ABSTRACT FROM AUTHOR]

Diatom blooms generated by the alleviation of iron limitation in high nitrate-low chlorophyll (HNLC) regions of the oceans often are composed of pennate diatoms of the genus Pseudo-nitzschia, many of which periodically produce the potent neurotoxin domoic acid. We show that toxigenic diatoms have an inducible high-affinity iron uptake capability that enables them to grow efficiently on iron complexed by strong organic ligands in seawater. This low-iron adaptive strategy requires copper and domoic acid, a copper chelator whose production increases sharply when both iron and copper are limiting. Addition of either domoic acid or copper to seawater improves the growth of Pseudo-nitzschia spp. on strongly complexed iron during deck incubation experiments with natural phytoplankton. Our findings indicate that domoic acid is a functional component of the unusual high-affinity iron acquisition system of these organisms. This system may help explain why Pseudo-nitzschia spp. are persistent seed populations in oceanic HNLC regions, as well as in some neritic regions. Our findings also indicate that in the absence of an adequate copper supply, iron-limited natural populations of Pseudo-nitzschia will become increasingly toxic. [ABSTRACT FROM AUTHOR]

Chromophoric dissolved organic matter (CDOM) is a major component of the total dissolved organic matter in seawater, and it can interfere significantly with oceanographic remote sensing in nearshore waters. Coastal marine CDOM comprises an undefined, likely rapidly changing mixture of terrestrially and marine-derived substances. Flow Field-Flow Fractionation (FlFFF) offers a novel approach for separating the colloidal (high molecular weight) fraction of CDOM into broad size continuums that can offer insights to the characteristics and reactivity of CDOM constituents. FlFFF analyses of seawaters in and around the Mississippi Plume were performed during high and low flow conditions and the results compared to analyses of phytoplankton cultures and waters from a coastal estuary having low freshwater inputs. FlFFF fractograms displayed major differences in the size distribution of CDOM between offshore in the Gulf of Mexico (GOMex) and the Mississippi River plume. Colloidal size distributions in nearshore surface waters out of the immediate influence of the Mississippi Plume contained a mixture of features seen in offshore waters, plume waters, and in phytoplankton cultures. Plume waters had a high abundance of larger colloidal phases but continued dilution with coastal waters led to preferential losses of mid-sized colloidal matter. Colloidal size spectra in offshore waters of the GOMex during spring were similar to that observed in estuarine waters after the spring bloom. These preliminary findings suggest that the colloidal size spectrum of CDOM may provide information on its provenance and the relative mixtures of terrestrial and marine components. [Copyright &y& Elsevier]

Recent work demonstrates that the micronutrient iron may strongly influence the magnitude and character of algal production in nearshore waters due in part to the higher but variable iron requirements of neritic phytoplankton. However, ascertaining the direct effects of iron nutrition in coastal waters has been forestalled by our inability to experimentally regulate ambient iron availability independent of other factors. We present here results from size-fractionated iron uptake experiments showing that increasing concentrations of the siderophore Desferriferrioxime B (DFB) progressively decreases the biological availability of iron tracer added to natural seawater. These findings extend those of previous studies showing that high concentrations of DFB induce iron limitation of phytoplankton in coastal waters. Similar tests with two siderophores (P1P and PCC7002 No. 1) isolated from marine prokaryotes showed little or no impact on short-term iron uptake in these natural population cultures. DFB additions did not influence the short-term uptake of carbon indicating that its inhibitory effect was not due to general toxicity to the cells. Uptake rates of iron tracer in the large (>5.0 μm) phytoplankton fraction decreased linearly with increasing DFB concentrations, becoming undetectable at ≥3 nM DFB, or ∼5× over ambient dissolved iron concentrations. The decrease in iron availability with DFB addition was equally dramatic for the ultraplankton (0.2–5.0 μm), but in this case low-level tracer uptake (∼10%) persisted even at high DFB concentrations (3–500 nM). Our experimental findings are combined with a preliminary kinetic model to suggest that iron equilibration among the natural ligand classes (L1, L2) and DFB may require an adjunctive (or associative) ligand substitution mechanism to explain the very rapid effect that DFB exerts on iron uptake when added to seawater. Even so, several hours to days likely are needed for the equilibration of added iron among DFB and natural ligands when low-level (e.g., 0.5 nM) DFB concentrations are employed. Model results provide indirect support to earlier suggestions that large eukaryotic phytoplankton extract iron from the weaker class of natural ligands (Fe(III)L2). The combination of iron enrichment and DFB amendments provides a practical means for studying how iron influences algal production, carbon cycling and phytoplankton species composition in nearshore waters. [Copyright &y& Elsevier]

The chemical speciation of iron in seawater is controlled by complexation with organic ligands, the character of which likely regulates which phytoplankton groups can readily access this resource. Evidence from the IronEx II mesoscale iron enrichment experiment provides some insight to this regulation. Dissolved iron (<0.4 μm) in the enriched surface waters during IronEx II was partitioned into colloidal (>1 kDa–0.4 μm) and soluble (<1 kDa) size fractions using cross flow filtration to better delineate iron dynamics with respect to phytoplankton growth. While dissolved concentrations in the patch increased by two orders of magnitude to ∼2 nM Fe, soluble concentrations only roughly doubled to ∼35 pM Fe, and this change occurred only during the first few days of the experiment. The subsequent decrease in soluble iron to ambient levels coincided with a dramatic increase in chlorophyll a, indicating that biological demand was responsible for the disappearance of soluble iron. This decrease also coincided with preferential drawdown of silicic acid over nitrate in the patch, indicating that diatoms were experiencing iron stress even as the bloom developed. Even so, calculations of the diffusional flux and iron uptake kinetics at the cellular level reveal that the concentrations of soluble iron during the later stages of the bloom were above that required to support continued rapid growth of the long, narrow pennate diatoms. This observation implies that the bulk of the organically bound soluble and colloidal iron was unavailable to meet the diatom growth requirements, and further that the measured increase in concentrations of strong Fe(III) complexing ligands impaired iron acquisition by diatoms. These findings indicate that excess macronutrients in HNLC waters might not be fully converted into diatom biomass even with repeated infusions of iron. [Copyright &y& Elsevier]

While solar ultraviolet radiation (UVR) is known to impact zooplankton, little has been documented on its impacts under elevated pCO 2. Here, we show that exposure to UVR decreased the feeding and survival rates of the copepod Acartia spinicauda , that artificial UV-B of 2.25 W·m−2 for 4 h resulted in a 52 % inhibition of its grazing rates and a 45 % reduction in survival rates compared to visible light alone. On the other hand, an increase in pCO 2 to 1000 μatm (pH drop of 0.4) immediately and significantly increased the UVR-induced inhibition of feeding. Subsequently, the combination of the high pCO 2 (1000 μatm) and UVR resulted in about 65 % lethal impact, with UV-A contributing 21 % and UV-B 44 % compared to the visible light alone and ambient pCO 2 conditions. While the copepod was shown to be able to sense and escape from UV-exposed areas, these findings suggest that UVR impacts on the copepod can be exacerbated with progressive ocean acidification or in high CO 2 waters, including upwelled regions. • Impact of UVR on the Physiological Activities of Copepod : • Exposure to UV-B radiation (2.25 W·m-2 for 4 hours) significantly inhibits the grazing rates (by 52 %) and reduces the survival rates (by 45 %) of the copepod Acartia spinicauda compared to visible light alone. • Synergistic Detrimental Effects of UVR and Elevated pCO 2 : • The combination of high pCO 2 and UVR results in approximately 65 % lethal impact on A. spinicauda , with UV-A contributing 21 % and UV-B contributing 44 % to the mortality compared to visible light alone and ambient pCO 2 conditions. • Photoprotective and Avoidance Behaviors : • A. spinicauda exhibits avoidance behavior by migrating to regions not exposed to UV radiation. [ABSTRACT FROM AUTHOR]

Presents research which studied the iron concentrations needed to fuel diatom production across the eastern equatorial Pacific Ocean. Phytoplankton growth in this region; Episodic increases in iron concentrations in the past; Records of cycles of plankton productivity; Influence of tectonic processes in the Papua New Guinea region and the effects of global climate forcing.

• HABs develop through the integration of physical, chemical, and temporal drivers. • We need a mechanistic understanding that reveals how climate affects these drivers. • Accelerating climate change in coastal regions signals the urgency for action. • New strategies, tools, and observatories for HABs will improve our forecast skill. • Focused research on subsets of HAB species would greatly accelerate advances. There is increasing concern that accelerating environmental change attributed to human-induced warming of the planet may substantially alter the patterns, distribution and intensity of Harmful Algal Blooms (HABs). Changes in temperature, ocean acidification, precipitation, nutrient stress or availability, and the physical structure of the water column all influence the productivity, composition, and global range of phytoplankton assemblages, but large uncertainty remains about how integration of these climate drivers might shape future HABs. Presented here are the collective deliberations from a symposium on HABs and climate change where the research challenges to understanding potential linkages between HABs and climate were considered, along with new research directions to better define these linkages. In addition to the likely effects of physical (temperature, salinity, stratification, light, changing storm intensity), chemical (nutrients, ocean acidification), and biological (grazer) drivers on microalgae (senso lato), symposium participants explored more broadly the subjects of cyanobacterial HABs, benthic HABs, HAB effects on fisheries, HAB modelling challenges, and the contributions that molecular approaches can bring to HAB studies. There was consensus that alongside traditional research, HAB scientists must set new courses of research and practices to deliver the conceptual and quantitative advances required to forecast future HAB trends. These different practices encompass laboratory and field studies, long-term observational programs, retrospectives, as well as the study of socioeconomic drivers and linkages with aquaculture and fisheries. In anticipation of growing HAB problems, research on potential mitigation strategies should be a priority. It is recommended that a substantial portion of HAB research among laboratories be directed collectively at a small sub-set of HAB species and questions in order to fast-track advances in our understanding. Climate-driven changes in coastal oceanographic and ecological systems are becoming substantial, in some cases exacerbated by localized human activities. That, combined with the slow pace of decreasing global carbon emissions, signals the urgency for HAB scientists to accelerate efforts across disciplines to provide society with the necessary insights regarding future HAB trends. [ABSTRACT FROM AUTHOR]

Marine primary producers are largely dependent on and shape the Earth's climate, although their relationship with climate varies over space and time. The growth of phytoplankton and associated marine primary productivity in most of the modern global ocean is limited by the supply of nutrients, including the micronutrient iron. The addition of iron via episodic and frequent events drives the biological carbon pump and promotes the sequestration of atmospheric carbon dioxide (CO2) into the ocean. However, the dependence between iron and marine primary producers adaptively changes over different geological periods due to the variation in global climate and environment. In this review, we examined the role and importance of iron in modulating marine primary production during some specific geological periods, that is, the Great Oxidation Event (GOE) during the Huronian glaciation, the Snowball Earth Event during the Cryogenian, the glacial–interglacial cycles during the Pleistocene, and the period from the last glacial maximum to the late Holocene. Only the change trend of iron bioavailability and climate in the glacial–interglacial cycles is consistent with the Iron Hypothesis. During the GOE and the Snowball Earth periods, although the bioavailability of iron in the ocean and the climate changed dramatically, the changing trend of many factors contradicted the Iron Hypothesis. By detangling the relationship among marine primary productivity, iron availability and oceanic environments in different geological periods, this review can offer some new insights for evaluating the impact of ocean iron fertilization on removing CO2 from the atmosphere and regulating the climate. [ABSTRACT FROM AUTHOR]

Discusses research which invoked polymer gel theory to explain the behavior of marine colloids. Role of marine colloids in ocean life; Research by Chin et al in this issue; Importance of research; What colloids are; Colloids affecting the behavior of carbon and metals in estuaries; Results of tracer studies; Factors controlling colloid residence times in sea water; Nonspecific surface interactions in colloid cycling; Missing biological aspect in study.

Tests the hypothesis that iron limits phytoplankton production and biomass in regions of the world's oceans otherwise rich in plant nutrients. Causes of the difference between bottle-scale and mesoscale iron enrichments; Increase in phytoplankton production and biomass upon iron enrichment.

This study focuses on the impacts of the COVID-19 pandemic on research and scholarship at a research university in the United States. Building on studies in higher education policy, we conceptualized the COVID-19 pandemic as a 'wicked problem' that is complex, nonlinear, unique, and requiring urgent solutions. Wicked problems highlight pre-existing struggles, and therefore, recent challenges in higher education inform the methods and the findings of this study. Qualitative and quantitative survey data from 408 faculty, staff, and students explicate the reasons for reduced research output and adaptations made for increased or sustained productivity, health, and wellness that influenced research activities. The analysis showed that most respondents experienced reduced productivity mostly due to increased work responsibilities, limited access to research fields, and inadequate resources. Despite self-reported reduced productivity, participants from the University we studied experienced increases in funding during the pandemic. Thus, the findings also reported on the adaptations for sustained or increased productivity. These included new research pursuits, participation in conference and learning opportunities across geographic regions, and purchase of computer equipment/accessories for home offices. A small percentage of respondents mentioned improved health and well-being; however, many linked reduced research activities to health and well-being issues such as anxiety and fear about the pandemic and being overwhelmed due to work and home-life expectations. Knowledge of the challenges and opportunities presented within the first year of the pandemic can provide a basis for solutions to wicked problems higher education may face in the future. [ABSTRACT FROM AUTHOR]

In September 2004 a large, nearly monospecific diatom bloom of Pseudo-nitzschia cuspidata off the coast of the state of Washington reached cell concentrations of 6.1 x 106 cells L-1 and produced maximum particulate domoic acid (pDA), dissolved domoic acid (dDA), and cellular domoic acid concentrations of 43 nmol L-1 1, 4 nmol L-1, and 63 pg cell-1, respectively. This bloom co-dominated the phytoplankton assemblage with the euglenoid Eutreptiella sp. in the Juan de Fuca eddy region, a known initiation site for toxigenic Pseudo-nitzschia blooms. Two isolates of P. cuspidata collected during separate cruises produced domoic acid (DA) in culture. During the September 2004 survey, 84% of the stations (n = 98) had detectable Pseudo-nitzschia and 78% had detectable pDA. There were no significant correlations between either pDA or cellular DA and ambient concentrations of macronutrients; however, when considering only those stations where Pseudo-nitzschia was present, pDA was positively correlated with chlorophyll a and negatively correlated with temperature (p < 0.01) at both 1- and 5-m depths. Correlations between cellular DA concentrations and total bacteria or cyanobacteria abundances were not significant. Variable ratios of pDA:dDA in the eddy region suggest that DA release was under cellular regulation by Pseudo-nitzschia. Stations where dissolved Fe concentrations were limiting (,0.5 nmol L-1) had the highest Pseudo-nitzschia abundances and pDA and cellular DA values. These results provide enticing field evidence of the role of Fe limitation in controlling cellular DA levels. [ABSTRACT FROM AUTHOR]

The distribution of dissolved iron(II) [Fe(II)] was studied in surface waters of the western subarctic Pacific during the Subarctic Pacific Iron Experiment for Ecosystem Dynamics Study-II (SEEDS II) iron enrichment experiment using highly sensitive flow injection-based luminol chemiluminescence. Vertical profiles of Fe(II) and total dissolved iron were measured outside of the fertilized patch to investigate the chemical speciation of iron in this high-nitrate low-chlorophyll (HNLC) region. Ambient total dissolved iron concentrations ranged from 50 pmol L-1 to 150 pmol L-1 depending on depth and sampling times. Unexpectedly, Fe(II) accounted for up to half of total dissolved iron, with concentrations up to ~50 pmol L-1. Fe(II) concentrations decreased exponentially with depth and were undetectable at depths below 50 m. There was no evidence of increased Fe(II) concentrations associated with the subsurface chlorophyll maximum, indicating that photolysis, rather than biological reduction of Fe(III), was the primary source of Fe(II). Because Fe(II) concentrations in the fertilized patch remained elevated for more than a week after enrichment, Fe(II) oxidation rates at near-ambient concentrations were measured. Indeed, the temperature-dependent Fe(II) oxidation rates were significantly slower than predicted by Fe(II) oxidation models and rates measured in ligand-free seawater. These findings suggest that Fe(II) binding ligands may exist in these HNLC waters, with conditional stability constants on the order of 108- 109 with respect to Fe2+. The accumulation of Fe(II) during daylight hours did not alleviate iron limitation of eukaryotic phytoplankton in these waters, contrary to expectations from recent iron uptake models. [ABSTRACT FROM AUTHOR]

The relationship between chromophoric dissolved organic matter (CDOM), colloidal DOM (.1 kDa), and phytoplankton biomass in marine waters of the Damariscotta estuary, Maine, was studied using flow field-flow fractionation (flow FFF). The goal was to determine whether temporal variability in CDOM in this region is due in part to rapid cycling of marine colloids. CDOM absorption of filtered (0.2 µm) seawater correlated positively with colloidal absorbance (r² = 0.772, p = 0.021). We observed changes in colloidal size spectra and CDOM optical properties associated with phytoplankton biomass. In particular, a significant positive correlation was found between the < 18 kDa colloidal fraction and chlorophyll a (Chl a) (r² = 0.819, p = 0.013). While we did not find significant relationships between Chl a and either CDOM absorption or the spectral slope of filtered seawater (r² and p values of 0.079, 0.590 and 0.111, 0.519, respectively), we did observe patterns of higher CDOM absorption and spectral slopes following periods of increased phytoplankton biomass. The spectral slope of colloidal material often was significantly lower than that of filtered seawater and normally varied significantly with colloidal size. These findings show that colloidal processes can contribute to CDOM optical signatures in coastal waters. [ABSTRACT FROM AUTHOR]

There is a common and long-standing belief that tropical butterflies are more striking in their coloration than those of cooler climates. It has been suggested that this is due to more intense biotic selection or mate selection in the tropics. We tested whether there were differences in coloration by examining the dorsal surface color properties of male butterflies from three regions of the western hemisphere: the Jatun-Satcha Reserve in lowland Ecuador (tropical), the state of Florida, USA (subtropical) and the state of Maine, USA (cool temperate). We digitally photographed the dorsal wing and body surface of male butterfly specimens from Maine, Florida, and Ecuador. For each photograph, we analyzed the mean and variation for the color-parameters that are thought to be related to colorfulness; namely Hue, saturation and intensity. Overall, the Ecuadorian sample exhibited more varied intensity, saturation, and Hue compared to the other regions. These results suggest a more complex assemblage of colors and patterns regionally and on a butterfly-by-butterfly basis in the tropics. The greater complexity of colors within each butterfly in our Ecuadorian sample suggests that tropical butterflies are indeed more 'colorful', at least by some measures. Possible reasons for this include stronger predation pressure selecting for aposematism, greater species diversity selecting for camouflage or warning coloration against potential predators, and easier recognition of potential mates in a species rich environment. [ABSTRACT FROM AUTHOR]

Iron is a bioactive trace element in seawater that regulates photosynthetic carbon dioxide drawdown and export from surface waters by phytoplankton in upward of 40% of the world's oceans. While autonomous sensor arrays are beginning to provide high-resolution data on temporal and spatial scales for some key oceanographic parameters, current analytical methods for iron are not amenable to autonomous platforms because of the need for user involvement and wet chemistry-based approaches. As a result, very large gaps remain in our understanding of iron distribution and chemistry in seawater. Here we present a straightforward nanostructure-based method to measure dissolved iron in natural seawater. The device comprises an iron-specific chelating biomolecule, desferrioxamine B (DFB), covalently immobilized on a mesoporous silica film. Changes in infrared spectral signatures of the immobilized DFB upon Fe(III) complexation provide an accurate and precise measure of iron on the surface of a chip exposed to seawater. The current system has a detection limit of ∼50 pM for a 1-L sample at pH 1.7 and was used to measure dissolved iron in subarctic Pacific waters without interference from other elements in sea-water. This technology provides a major step toward obtaining accurate iron measurements on autonomous research platforms. [ABSTRACT FROM AUTHOR]

Problem We have used an in vitro co-culture system consisting of early gestation macaque trophoblasts cultured on top of human uterine microvascular endothelial cells (UtMVECs) to investigate the inflammatory response of endothelial cells to trophoblasts under shear stress conditions. Method of study Uterine microvascular endothelial cells and trophoblasts were co-cultured in a parallel plate chamber under shear stress (15 dyn/cm2) conditions. The distribution and expression of endothelial intercellular adhesion molecule-1 (ICAM-1) was quantified by immunofluorescence image analysis and flow cytometry. Endothelial regulated upon activation normal T-cell expressed and secreted (RANTES) secretion was measured by enzyme-linked immunosorbent assay and permeability was assessed using fluorescein isothiocyanate-dextran. Results Intercellular adhesion molecule-1, but not vascular cell adhesion molecule-1 or platelet endothelial cell adhesion molecule-1, was re-distributed towards the downstream edge of endothelial cells when the cells were co-cultured with trophoblasts under shear stress conditions. Changes in ICAM-1 distribution were also observed when UtMVECs were co-cultured with trophoblast-conditioned medium under shear stress conditions. Incubation of UtMVECs with trophoblast-conditioned medium increased endothelial permeability, RANTES secretion, and trophoblast adhesion. Conclusion These data support the idea that trophoblasts induce an inflammatory response in uterine endothelial cells that could enhance trophoblast invasion and transmigration. [ABSTRACT FROM AUTHOR]

Commercial landings of sardines are known to show strong year‐to‐year fluctuations. A key driver is thought to be environmental variability, to which small forage fish are especially sensitive. We examined the utility of including environmental covariates in forecasts for landings of the Indian oil sardine using a long‐term time series of quarterly catches. Potentially influential variables examined included precipitation, upwelling intensity, sea surface temperature (SST), and chlorophyll‐a concentration. All of these have been shown to be important for oil sardine growth and survival, spawning and/or movement into the nearshore fishing regions. However, improving out‐of‐sample landings forecasts using environmental covariates has often proven elusive. We tested the inclusion of environmental covariates in forecast models using generalized additive models, which allow for non‐linear responses, and dynamic linear models, which allow for time‐varying responses. Only two environmental covariates improved out‐of‐sample prediction: the 2.5‐year average regional SST and precipitation over land during June–July. The most significant improvement was with the SST covariate and post‐monsoon landings with a 19%–22% reduction in mean‐squared prediction error. Models with the second best covariate, monsoon precipitation over land, provided a 4%–8% reduction in prediction error. We also tested large‐scale ocean climate teleconnection indices. One, an index of the Atlantic Multidecadal Oscillation, also improved out‐of‐sample predictions similarly to the multiyear average regional SST. The earth's changing climate is associated with both rapid warming in the Western Indian Ocean and changes to monsoon rainfall patterns. Our work highlights these as key variables that can improve forecasting of oil sardine landings. [ABSTRACT FROM AUTHOR]

A case of fatal sepsis due to Capnocytophaga species is described. Capnatophaga canimorsus and C. cynodegmi can cause localized wound infections and/or systemic infections in people who have been bitten, licked, scratched, or merely exposed to cats or dogs, especially splenectomized individuals. A thorough social, medical, and surgical history, the clinical presentation, and cultures are important in making the diagnosis of Capnocytophaga infections. It is important that the forensic pathologist be aware of this zoonotic disease. [ABSTRACT FROM AUTHOR]

In the context of global climate change, ocean iron fertilization (OIF) has been suggested as a potential geoengineering strategy to enhance the growth of marine phytoplankton, subsequently promote the ocean carbon sink, and ultimately regulate atmospheric carbon dioxide (CO 2) and mitigate climate change. However, in past artificial OIF experiments, the elevation of both net primary production and carbon export to the deep ocean is far less than anticipated. This discrepancy can be attributed to several key factors that strongly influence the efficiency of OIF and biological carbon pump (BCP) including iron bioavailability and retention time, the sensitivity of phytoplankton to iron limitation, the influence of viruses and other microorganisms comprising the microbial carbon pump (MCP), and non-biological carbon cycles. Although previous reviews have extensively summarized the outcomes of the past OIF experiments, the mechanisms and key factors that influence climate regulation mediated by OIF have not been elucidated. In this review, we analyze these mechanisms throughout the whole process from OIF, to phytoplankton physiological responses, to carbon dioxide removal (CDR) and sequestration in the ocean, and ultimately to CDR in the atmosphere and its impact on climate change. By examining both natural and artificial OIF cases, as well as recent advancements in phytoplankton physiological ecology and carbon pump theory, possible reasons leading to the inconsistencies between OIF and carbon export are explored. These comprehensive analyses are helpful to identify the key issues in regulating climate change by providing a reference and scientific approach to guide potential OIF attempts in the future. [ABSTRACT FROM AUTHOR]

• Growth rates of an Alexandrium catenella decrease at future temperature levels. • Growth rates of co-occurring non-toxic dinoflagellate competitors increase. • The findings suggest fewer future toxic blooms in the southern Gulf of Maine. • But more toxic blooms may occur in the northeastern Gulf of Maine. Climate driven increases in ocean temperature and pCO 2 have the potential to alter the growth and prevalence of future Harmful Algal Blooms (HABs), but systematic studies on how climate drivers influence toxic algal species relative to non-toxic phytoplankton are lacking. In particular, little is known about how future climate scenarios will affect the growth of the toxic dinoflagellate Alexandrium catenella , which is responsible for the paralytic shellfish poisoning (PSP) events that threaten the health and economy of coastal communities in the Gulf of Maine and elsewhere. The growth responses of A. catenella and two other naturally co-occurring dinoflagellates in the Gulf of Maine— Scrippsiella sp., and Amphidinium carterae— were studied in mono and mixed species cultures. Experimental treatments tested the effects of elevated temperature (20 °C), lower pH (7.8), and the combination of elevated temperature and lower pH on growth rates relative to those in near-current conditions (15 °C; pH 8.1). Growth rates of A. catenella decreased under elevated temperature and lower pH conditions, a response that was largely attributable to the effect of temperature. In contrast, growth rates of Scrippsiella sp. and A. carterae increased under elevated temperature and lower pH conditions, with temperature also being the primary driver of the response. These trends did not change substantially when these species were grown in mixed cultures (A. catenella + Scrippsiella sp., and A. catenella + A. carterae), indicating that allelopathic or competitive interactions did not affect the experimental outcome under the conditions tested. These findings suggest that A. catenella blooms may become less prevalent in the southern regions of the Gulf of Maine, but potentially more prevalent in the northeastern regions of the Gulf of Maine with continued climate change. [ABSTRACT FROM AUTHOR]

Abstract Blooms of Pseudo-nitzschia species are frequent, but presently unpredictable, in the Juan de Fuca Eddy region off the coasts of Washington (US) and British Columbia (Canada). This upwelling eddy region is proposed to be the bloom commencement site, before cells are entrained into the coastal surface currents. During a shipboard study, we characterized the different stages of the Pseudo-nitzschia bloom development from its initiation and intensification, to its eventual sinking and dissipation. Specifically, we followed a water mass using lagrangian ARGOS-tracked drifters released at the eddy water mass and quantified production of dissolved and particulate domoic acid, and the physiological status of the Pseudo-nitzschia cells with regards to photosynthesis, nutrient needs and sinking rates, along with its relationship with competing species – in this case, the marine euglenoid, Eutreptiella spp. The drifter study allows for an interpretation of the presence or absence of Pseudo-nitzschia and domoic acid against active environmental factors – particularly copper and iron. [ABSTRACT FROM AUTHOR]

Intense blooms of the heterotrophic dinoflagellate, green Noctiluca scintillans, have been reported annually in the Northern Arabian Sea since the early 2000s. Although not known to produce organic toxins, these blooms are still categorized as a harmful due to their association with massive fish mortalities. Recent work has attributed these blooms to the vertical expansion of the oxygen minimum zone, driven by cultural eutrophication from major coastal cities in western India. As diatoms are preferred prey of green Noctiluca scintillans, more frequent blooms of this mixotroph will likely impact the productivity of important fisheries in the region. The present study uses a satellite algorithm to determine the distribution of both diatom and green Noctiluca blooms in the Northeastern Arabian Sea from 2009 to 2016. The results from shipboard microscopy of phytoplankton community composition were used to validate the satellite estimates. The satellite algorithm showed 76% accuracy for detection of green Noctiluca and 92% for diatoms. Shipboard measurements and data from biogeochemical-Argo floats were used to assess the relationship between oxygen concentrations and green Noctiluca blooms in the Northeastern Arabian Sea. Regardless of the presence of a Noctiluca bloom, the dissolved oxygen in the photic zone was always >70% saturated, with an average oxygen saturation >90%. The variability in the relative abundance of diatoms and green Noctiluca is not correlated with changes in oxygen concentration. These findings provide no evidence that cultural eutrophication has contributed to the decadal scale shifts in plankton composition in the Northeastern Arabian Sea oceanic waters. Conversely, the climatic warming of surface waters would have intensified stratification, thereby reducing net nutrient flux to the photic zone and decreasing silicate to nitrate ratios (Si:N); both factors that could increase the competitive advantage of the mixotroph, green Noctiluca , over diatoms. If so, the decadal-scale trajectory of phytoplankton community composition in the Northeastern Arabian Sea may be a harbinger of future climate-driven change in other productive oceanic systems. [ABSTRACT FROM AUTHOR]

Ocean Acidification (OA) effects on marine plankton are most often considered in terms of inorganic carbon chemistry, but decreasing pH may influence other aspects of cellular metabolism. Here we present the effects of OA on the fatty acid (FA) content and composition of an artificial phytoplankton community ( Phaeodactylum tricornutum , Thalassiosira weissflogii , and Emiliania huxleyi ) in a fully replicated, ∼4 m 3 mesocosm study in subtropical coastal waters (Wuyuan Bay, China, 24.52°N, 117.18°E) at present day (400 μatm) and elevated (1000 μatm) p CO 2 concentrations. Phytoplankton growth occurred in three phases during the 33-day experiment: an initial exponential growth leading to senescence and a subsequent decline phase. Phytoplankton sampled from these mesocosms were fed to mesozooplankton collected by net haul from Wuyuan Bay. Concentrations of saturated fatty acids (SFA) in both phytoplankton and mesozooplankton remained high under acidified and non-acidified conditions. However, polyunsaturated fatty acids (PUFA) and monounsaturated fatty acids (MUFA) increased significantly more under elevated p CO 2 during the late exponential phase (Day 13), indicating increased nutritional value for zooplankton and higher trophic levels. Indeed, uptake rates of the essential FA docosahexaenoic acid (C20:5n3, DHA) increased in mesozooplankton under acidified conditions. However, mesozooplankton grazing rates decreased overall with elevated p CO 2 . Our findings show that these selected phytoplankton species have a relatively high tolerance to acidification in terms of FA production, and local mesozooplankton in these subtropical coastal waters can maintain their FA composition under end of century ocean acidification conditions. [ABSTRACT FROM AUTHOR]

Background & Aims Epidemiological data on primary sclerosing cholangitis ( PSC) outside the Northern hemisphere are limited. Similarly, the impact of inflammatory bowel disease ( IBD) on PSC outcomes remains unclear. We aimed to study the epidemiology and outcomes of PSC patients with and without IBD in an Australian cohort. Methods We retrospectively studied PSC patients attending two tertiary referral hospitals over 20 years. Diagnosis of PSC was made according to international guidelines by positive cholangiography and/or liver biopsy (for small duct PSC) with supporting clinical and laboratory evidence. Results Of 208 PSC patients (61% male) were studied (2271patient-years follow-up). The median age of PSC diagnosis was similar for PSC- IBD and PSC-only patients (40 years vs 42 years, P = .35). All 33 deaths occurred in PSC- IBD patients while there were no deaths in PSC-only patients (21% vs 0%, P < .01). However, there were no significant differences in liver transplantation ( PSC-only 25% vs PSC- IBD 31%, P = .45) and transplant-free survival between PSC-only and PSC- IBD patients ( P = .43). On multivariate Cox regression, only elevated international normalized ratio ( INR) was associated with a greater risk of death or liver transplant ( HR 2.0, 95% CI 1.1-3.6, P = .02). Development of gastrointestinal malignancy was higher in the PSC- IBD group compared to PSC-only group (22% vs 2%, P < .01). Conclusion Australian PSC patients have similar characteristics compared to European and North American cohorts. IBD is a significant predictor of gastrointestinal malignancies. Deaths were more common in PSC- IBD but overall transplant-free survival remained similar in PSC- IBD and PSC-only groups. An elevated INR was an independent predictor of death or liver transplantation. [ABSTRACT FROM AUTHOR]

Background: Hepatocytes metabolize the vast majority of ingested ethanol. This metabolic activity results in hepatic toxicity and impairs the ability of hepatocytes to replicate. Previous work by our group has shown that ethanol metabolism results in a G2/M cell cycle arrest. The intent of these studies was to discern the roles of acetaldehyde and reactive oxygen, two of the major by-products of ethanol metabolism, in the G2/M cell cycle arrest. Methods: To investigate the role of ethanol metabolites in the cell cycle arrest, VA-13 and VL-17A cells were used. These are recombinant Hep G2 cells that express alcohol dehydrogenase or alcohol dehydrogenase and cytochrome P450 2E1, respectively. Cells were cultured with or without ethanol, lacking or containing the antioxidants N-acetylcysteine (NAC) or trolox, for three days. Cellular accumulation was monitored by the DNA content of the cultures. The accumulation of the cyclin-dependent kinase, Cdc2 in the inactive phosphorylated form (p-Cdc2) and the cyclin-dependent kinase inhibitor p21 were determined by immunoblot analysis. Results: Cultures maintained in the presence of ethanol demonstrated a G2/M cell cycle arrest that was associated with a reduction in DNA content and increased levels of p-Cdc2 and p21, compared with cells cultured in its absence. Inclusion of antioxidants in the ethanol containing media was unable to rescue the cells from the cell cycle arrest or these ethanol metabolism-mediated effects. Additionally, culturing the cells in the presence of acetaldehyde alone resulted in increased levels of p-Cdc2 and p21. Conclusions: Acetaldehyde produced during ethanol oxidation has a major role in the ethanol metabolism-mediated G2/M cell cycle arrest, and the concurrent accumulation of p21 and p-Cdc2. Although reactive oxygen species are thought to have a significant role in ethanol-induced hepatocellular damage, they may have a less important role in the inability of hepatocytes to replace dead or damaged cells. [ABSTRACT FROM AUTHOR]

The outer membrane of a bacterium is composed of chemical and biological components that carry specific molecular information related to strains, growth stages, expressions to stimulation, and maybe even geographic differences. In this work, we demonstrate that the biochemical information embedded in the outer membrane can be used for rapid detection and identification of pathogenic bacteria using surface-enhanced Raman spectroscopy (SERS). We used seven different strains of the marine pathogen Vibrio parahaemolyticus as a model system. The strains represent four genetically distinct clades isolated from clinical and environmental sources in Washington, U.S.A. The unique quasi-3D (Q3D) plasmonic nanostructure arrays, optimized using finite-difference time-domain (FDTD) calculations, were used as SERS-active substrates for sensitive and reproducible detection of these bacteria. SERS barcodes were generated on the basis of SERS spectra and were used to successfully detect individual strains in both blind samples and mixtures. The sensing and detection methods developed in this work could have broad applications in the areas of environmental monitoring, biomedical diagnostics, and homeland security. [ABSTRACT FROM AUTHOR]