The reminiscence bump and the self: evidence from five studies on positive and negative memories.

A plethora of studies have shown that people persistently remember public and personal events experienced during adolescence and early adulthood, particularly with a positive valence. In five studies, we investigate the reminiscence bump (RB) for positive and negative memories of public events (Studies 1 and 2), private events (Study 3), music-related events (Study 4), and cross-cultural memory differences (i.e., China and US) (Study 5). Participants retrieved either one positive or one negative memory, indicated their Age of Encoding, and provided secondary measures, i.e., memory vividness and rehearsal (Studies 1 and 3) and emotional intensity (Studies 2 and 4). About 10,000 memories were collected and positive memories appeared generally older than negative recollections, but the RB emerged for both positive and negative memories. Furthermore, the peak was earlier for positive memories of public events (<15 years old) than for negative memories (20-40 years), while no differences were found for private events or music-related experiences (15-25 years). Chinese had their RB later than US respondents. Finally, autobiographical recollections have moderate to low associations with secondary measures of phenomenological features of memory. These findings are consistent with the identity-formation theory, providing additional and important information on the development of the Self.

Fine-scale structures as spots of increased fish concentration in the open ocean.

Oceanic frontal zones have been shown to deeply influence the distribution of primary producers and, at the other extreme of the trophic web, top predators. However, the relationship between these structures and intermediate trophic levels is much more obscure. In this paper we address this knowledge gap by comparing acoustic measurements of mesopelagic fish concentrations to satellite-derived fine-scale Lagrangian Coherent Structures in the Indian sector of the Southern Ocean. First, we demonstrate that higher fish concentrations occur more frequently in correspondence with strong Lagrangian Coherent Structures. Secondly, we illustrate that, while increased fish densities are more likely to be observed over these structures, the presence of a fine-scale feature does not imply a concomitant fish accumulation, as other factors affect fish distribution. Thirdly, we show that, when only chlorophyll-rich waters are considered, front intensity modulates significantly more the local fish concentration. Finally, we discuss a model representing fish movement along Lagrangian features, specifically built for mid-trophic levels. Its results, obtained with realistic parameters, are qualitatively consistent with the observations and the spatio-temporal scales analysed. Overall, these findings may help to integrate intermediate trophic levels in trophic models, which can ultimately support management and conservation policies.

Hydrothermal vents trigger massive phytoplankton blooms in the Southern Ocean.

Hydrothermal activity is significant in regulating the dynamics of trace elements in the ocean. Biogeochemical models suggest that hydrothermal iron might play an important role in the iron-depleted Southern Ocean by enhancing the biological pump. However, the ability of this mechanism to affect large-scale biogeochemistry and the pathways by which hydrothermal iron reach the surface layer have not been observationally constrained. Here we present the first observational evidence of upwelled hydrothermally influenced deep waters stimulating massive phytoplankton blooms in the Southern Ocean. Captured by profiling floats, two blooms were observed in the vicinity of the Antarctic Circumpolar Current, downstream of active hydrothermal vents along the Southwest Indian Ridge. These hotspots of biological activity are supported by mixing of hydrothermally sourced iron stimulated by flow-topography interactions. Such findings reveal the important role of hydrothermal vents on surface biogeochemistry, potentially fueling local hotspot sinks for atmospheric CO2 by enhancing the biological pump.

A Satellite-Based Lagrangian View on Phytoplankton Dynamics.

The well-lit upper layer of the open ocean is a dynamical environment that hosts approximately half of global primary production. In the remote parts of this environment, distant from the coast and from the seabed, there is no obvious spatially fixed reference frame for describing the dynamics of the microscopic drifting organisms responsible for this immense production of organic matter-the phytoplankton. Thus, a natural perspective for studying phytoplankton dynamics is to follow the trajectories of water parcels in which the organisms are embedded. With the advent of satellite oceanography, this Lagrangian perspective has provided valuable information on different aspects of phytoplankton dynamics, including bloom initiation and termination, spatial distribution patterns, biodiversity, export of carbon to the deep ocean, and, more recently, bottom-up mechanisms that affect the distribution and behavior of higher-trophic-level organisms. Upcoming submesoscale-resolving satellite observations and swarms of autonomous platforms open the way to the integration of vertical dynamics into the Lagrangian view of phytoplankton dynamics.

Dispersion/dilution enhances phytoplankton blooms in low-nutrient waters.

Spatial characteristics of phytoplankton blooms often reflect the horizontal transport properties of the oceanic turbulent flow in which they are embedded. Classically, bloom response to horizontal stirring is regarded in terms of generation of patchiness following large-scale bloom initiation. Here, using satellite observations from the North Pacific Subtropical Gyre and a simple ecosystem model, we show that the opposite scenario of turbulence dispersing and diluting fine-scale (∼1-100 km) nutrient-enriched water patches has the critical effect of regulating the dynamics of nutrients-phytoplankton-zooplankton ecosystems and enhancing accumulation of photosynthetic biomass in low-nutrient oceanic environments. A key factor in determining ecological and biogeochemical consequences of turbulent stirring is the horizontal dilution rate, which depends on the effective eddy diffusivity and surface area of the enriched patches. Implementation of the notion of horizontal dilution rate explains quantitatively plankton response to turbulence and improves our ability to represent ecological and biogeochemical processes in oligotrophic oceans.

Estimating planktonic diversity through spatial dominance patterns in a model ocean.

In the open ocean, the observation and quantification of biodiversity patterns is challenging. Marine ecosystems are indeed largely composed by microbial planktonic communities whose niches are affected by highly dynamical physico-chemical conditions, and whose observation requires advanced methods for morphological and molecular classification. Optical remote sensing offers an appealing complement to these in-situ techniques. Global-scale coverage at high spatiotemporal resolution is however achieved at the cost of restrained information on the local assemblage. Here, we use a coupled physical and ecological model ocean simulation to explore one possible metrics for comparing measures performed on such different scales. We show that a large part of the local diversity of the virtual plankton ecosystem - corresponding to what accessible by genomic methods - can be inferred from crude, but spatially extended, information - as conveyed by remote sensing. Shannon diversity of the local community is indeed highly correlated to a 'seascape' index, which quantifies the surrounding spatial heterogeneity of the most abundant functional group. The error implied in drastically reducing the resolution of the plankton community is shown to be smaller in frontal regions as well as in regions of intermediate turbulent energy. On the spatial scale of hundreds of kms, patterns of virtual plankton diversity are thus largely sustained by mixing communities that occupy adjacent niches. We provide a proof of principle that in the open ocean information on spatial variability of communities can compensate for limited local knowledge, suggesting the possibility of integrating in-situ and satellite observations to monitor biodiversity distribution at the global scale.

Quasi-planktonic behavior of foraging top marine predators.

Monitoring marine top predators is fundamental for assessing the health and functioning of open ocean ecosystems. Although recently tracking observations have substantially increased, factors determining the horizontal exploration of the ocean by marine predators are still largely unknown, especially at the scale of behavioral switches (1-100 km, days-weeks). It is commonly assumed that the influence of water movement can be neglected for animals capable of swimming faster than the current. Here, we challenge this assumption by combining the use of biologging (GPS and accelerometry), satellite altimetry and in-situ oceanographic data (ADCP and drifting buoys) to investigate the effect of the mesoscale ocean dynamics on a marine predator, the southern elephant seal. A Lagrangian approach reveals that trajectories of elephant seals are characterized by quasi-planktonic bouts where the animals are horizontally drifting. These bouts correspond to periods of increased foraging effort, indicating that in the quasi-planktonic conditions energy is allocated to diving and chasing, rather than in horizontal search of favourable grounds. These results suggest that mesoscale features like eddies and fronts may act as a focal points for trophic interactions not only by bottom-up modulation of nutrient injection, but also by directly entraining horizontal displacements of the upper trophic levels.

Influence of oceanographic structures on foraging strategies: Macaroni penguins at Crozet Islands.

BACKGROUND: In the open ocean, eddies and associated structures (fronts, filaments) have strong influences on the foraging activities of top-predators through the enhancement and the distribution of marine productivity, zooplankton and fish communities. Investigating how central place foragers, such as penguins, find and use these physical structures is crucial to better understanding their at-sea distribution. In the present study, we compared the travel heading and speed of the world's most abundant penguin, the Macaroni penguin (Eudyptes chrysolophus), with the distribution of surface physical structures (large-scale fronts, eddies and filaments). RESULTS: The study was performed during December 2012 in the Crozet Archipelago (46.42° S; 51.86° E), South Indian Ocean. Six males at incubation stage were equipped with GPS loggers to get their trajectories. We used Eulerian and Lagrangian methods to locate large-scale fronts, mesoscale eddies (10-100 km) and part of the sub-mesoscale structures (<10 km, filaments) at the surface of the ocean. By comparing the positions of birds and these structures, we show that Macaroni penguins: i) target the sub Antarctic Front; ii) increase their foraging activity within a highly dynamic area, composed of eddy fields and filamentary structures; and iii) travel in the same direction as the predominant currents. CONCLUSIONS: We show that penguins adjust their travel speed and movement during their whole trips in relation with the oceanographic structures visited. At a large scale, we hypothesize that Macaroni penguins target the sub Antarctic Front to find profitable patches of their main prey. At finer scale, Macaroni penguin may adopt a horizontal drifting behavior in strong currents, which could be a way to minimize costs of displacement.

The dynamical landscape of marine phytoplankton diversity.

Observations suggest that the landscape of marine phytoplankton assemblage might be strongly heterogeneous at the dynamical mesoscale and submesoscale (10-100 km, days to months), with potential consequences in terms of global diversity and carbon export. But these variations are not well documented as synoptic taxonomic data are difficult to acquire. Here, we examine how phytoplankton assemblage and diversity vary between mesoscale eddies and submesoscale fronts. We use a multi-phytoplankton numerical model embedded in a mesoscale flow representative of the North Atlantic. Our model results suggest that the mesoscale flow dynamically distorts the niches predefined by environmental contrasts at the basin scale and that the phytoplankton diversity landscape varies over temporal and spatial scales that are one order of magnitude smaller than those of the basin-scale environmental conditions. We find that any assemblage and any level of diversity can occur in eddies and fronts. However, on a statistical level, the results suggest a tendency for larger diversity and more fast-growing types at fronts, where nutrient supplies are larger and where populations of adjacent water masses are constantly brought into contact; and lower diversity in the core of eddies, where water masses are kept isolated long enough to enable competitive exclusion.

Ocean plankton. Structure and function of the global ocean microbiome.

Microbes are dominant drivers of biogeochemical processes, yet drawing a global picture of functional diversity, microbial community structure, and their ecological determinants remains a grand challenge. We analyzed 7.2 terabases of metagenomic data from 243 Tara Oceans samples from 68 locations in epipelagic and mesopelagic waters across the globe to generate an ocean microbial reference gene catalog with >40 million nonredundant, mostly novel sequences from viruses, prokaryotes, and picoeukaryotes. Using 139 prokaryote-enriched samples, containing >35,000 species, we show vertical stratification with epipelagic community composition mostly driven by temperature rather than other environmental factors or geography. We identify ocean microbial core functionality and reveal that >73% of its abundance is shared with the human gut microbiome despite the physicochemical differences between these two ecosystems.

Ocean plankton. Determinants of community structure in the global plankton interactome.

Species interaction networks are shaped by abiotic and biotic factors. Here, as part of the Tara Oceans project, we studied the photic zone interactome using environmental factors and organismal abundance profiles and found that environmental factors are incomplete predictors of community structure. We found associations across plankton functional types and phylogenetic groups to be nonrandomly distributed on the network and driven by both local and global patterns. We identified interactions among grazers, primary producers, viruses, and (mainly parasitic) symbionts and validated network-generated hypotheses using microscopy to confirm symbiotic relationships. We have thus provided a resource to support further research on ocean food webs and integrating biological components into ocean models.

Reduced level of 25-hydroxyvitamin D in chronic/relapsing Alopecia Areata.

Current observations link vitamin D deficiency to many autoimmune diseases. There are limited data on vitamin D in Alopecia Areata, an autoimmune disease which in our experience shows seasonality in most of its remitting-relapsing forms. Our results demonstrate the presence of insufficiency of 25-hydroxyvitamin D (25OH-D) in many patients with various clinical forms, correlated with the expected increase of the values of Parathyroid Hormone (PTH). This could suggest the possible clinical use of vitamin D in the management of this frustrating disease.

Can we detect oceanic biodiversity hotspots from space?

Understanding the variability of marine biodiversity is a central issue in microbiology. Current observational programs are based on in situ studies, but their implementation at the global scale is particularly challenging, owing to the ocean extent, its temporal variability and the heterogeneity of the data sources on which compilations are built. Here, we explore the possibility of identifying phytoplanktonic biodiversity hotspots from satellite. We define a Shannon entropy index based on patchiness in ocean color bio-optical anomalies. This index provides a high resolution (1 degree) global coverage. It shows a relation to temperature and mid-latitude maxima in accordance with those previously evidenced in microbiological biodiversity model and observational studies. Regional maxima are in remarkable agreement with several known biodiversity hotspots for plankton organisms and even for higher levels of the marine trophic chain, as well as with some in situ planktonic biodiversity estimates (from Atlantic Meridional Transect cruise). These results encourage to explore marine biodiversity with a coordinated effort of the molecular, ecological and remote sensing communities.

Frigatebird behaviour at the ocean-atmosphere interface: integrating animal behaviour with multi-satellite data.

Marine top predators such as seabirds are useful indicators of the integrated response of the marine ecosystem to environmental variability at different scales. Large-scale physical gradients constrain seabird habitat. Birds however respond behaviourally to physical heterogeneity at much smaller scales. Here, we use, for the first time, three-dimensional GPS tracking of a seabird, the great frigatebird (Fregata minor), in the Mozambique Channel. These data, which provide at the same time high-resolution vertical and horizontal positions, allow us to relate the behaviour of frigatebirds to the physical environment at the (sub-)mesoscale (10-100 km, days-weeks). Behavioural patterns are classified based on the birds' vertical displacement (e.g. fast/slow ascents and descents), and are overlaid on maps of physical properties of the ocean-atmosphere interface, obtained by a nonlinear analysis of multi-satellite data. We find that frigatebirds modify their behaviours concurrently to transport and thermal fronts. Our results suggest that the birds' co-occurrence with these structures is a consequence of their search not only for food (preferentially searched over thermal fronts) but also for upward vertical wind. This is also supported by their relationship with mesoscale patterns of wind divergence. Our multi-disciplinary method can be applied to forthcoming high-resolution animal tracking data, and aims to provide a mechanistic understanding of animals' habitat choice and of marine ecosystem responses to environmental change.

Deep carbon export from a Southern Ocean iron-fertilized diatom bloom.

Fertilization of the ocean by adding iron compounds has induced diatom-dominated phytoplankton blooms accompanied by considerable carbon dioxide drawdown in the ocean surface layer. However, because the fate of bloom biomass could not be adequately resolved in these experiments, the timescales of carbon sequestration from the atmosphere are uncertain. Here we report the results of a five-week experiment carried out in the closed core of a vertically coherent, mesoscale eddy of the Antarctic Circumpolar Current, during which we tracked sinking particles from the surface to the deep-sea floor. A large diatom bloom peaked in the fourth week after fertilization. This was followed by mass mortality of several diatom species that formed rapidly sinking, mucilaginous aggregates of entangled cells and chains. Taken together, multiple lines of evidence-although each with important uncertainties-lead us to conclude that at least half the bloom biomass sank far below a depth of 1,000 metres and that a substantial portion is likely to have reached the sea floor. Thus, iron-fertilized diatom blooms may sequester carbon for timescales of centuries in ocean bottom water and for longer in the sediments.

Analysis of telomere dynamics in peripheral blood cells from patients with Lynch syndrome.

BACKGROUND: In patients with Lynch syndrome, germline mutations in DNA mismatch repair (MMR) genes cause a high risk of developing a broad spectrum of cancers. To date, the management of patients with Lynch syndrome has represented a major challenge because of large variations in age at cancer onset. Several factors, including genetic anticipation, have been proposed to explain this phenotypic heterogeneity, but the molecular mechanisms remain unknown. Telomere shortening is a common event in tumorigenesis and also has been observed in different familial cancers. In this study, the authors investigated the possibility of a relation between telomere length and cancer onset in patients with Lynch syndrome. METHODS: The mean telomere length was measured using quantitative polymerase chain reaction in peripheral blood samples from a control group of 50 individuals, from 31 unaffected mutation carriers, and from 43 affected patients, and the results were correlated with both gene mutation and cancer occurrence. In affected patients, telomere attrition was correlated with age at cancer onset. In all patients, a t test was used to assess the linearity of the regression. RESULTS: A significant correlation between telomere length and age was observed in both affected and unaffected mutation carriers (P = .0016 and P = .004, respectively) and in mutS homolog 2 (MSH2) mutation carriers (P = .0002) but not in mutL homolog 1 (MLH1) mutation carriers. Telomere attrition was correlated significantly with age at onset in MSH2 carriers (P = .004), whereas an opposite trend toward longer telomeres in patients with delayed onset was observed in MLH1 carriers. CONCLUSIONS: The current data suggested that telomere dynamics differ between MLH1 and MSH2 mutation carriers. It is possible that subtle, gene-specific mechanisms can be linked to cancer onset and anticipation in patients with Lynch syndrome.

Fluid dynamical niches of phytoplankton types.

The biogeochemical role of phytoplanktonic organisms strongly varies from one plankton type to another, and their relative abundance and distribution have fundamental consequences at the global and climatological scales. In situ observations find dominant types often associated to specific physical and chemical water properties. However, the mechanisms and spatiotemporal scales by which marine ecosystems are organized are largely not known. Here we investigate the spatiotemporal organization of phytoplankton communities by combining multisatellite data, notably high-resolution ocean-color maps of dominant types and altimetry-derived Lagrangian diagnostics of the surface transport. We find that the phytoplanktonic landscape is organized in (sub-)mesoscale patches (10-100 km) of dominant types separated by physical fronts induced by horizontal stirring. These physical fronts delimit niches supported by water masses of similar history and whose lifetimes are comparable with the timescale of the bloom onset (few weeks). The resonance between biological activity and physical processes suggest that the spatiotemporal (sub-)mesoscales associated to stirring are determinant in the observation and modeling of marine ecosystems.

Liver involvement in a large cohort of patients with hereditary hemorrhagic telangiectasia: echo-color-Doppler vs multislice computed tomography study.

BACKGROUND/AIMS: Hepatic arterio-venous malformations (HAVMs) have been found in 74% of hereditary hemorrhagic telangiectasia (HHT) patients with multislice CT (MSCT). This single-blind study aimed to compare the diagnostic accuracy of echo-color-Doppler with MSCT and identify the most sensitive ultrasound criteria indicating hepatic shunts. METHODS: One hundred and fifty-three HHT patients were systematically screened for HAVMs by biological tests, abdominal MSCT and echo-color-Doppler. Twenty-five normal subjects and 15 cirrhotic patients were also included as control groups. Both intrahepatic ("color spots" and hypervascularization) and extrahepatic parameters (diameter, flow velocity and tortuosity of hepatic artery and diameter and flow velocity of portal/hepatic vein) were utilized. "Color-spots" are defined as subcapsular vascular spots with a high-velocity arterial blood flow and low resistivity index and can identify extremely small HAVMs. RESULTS: CT was positive in 128/153 (84%) patients and Doppler color spots were found in 131/153 (86%) patients. The sensitivity, specificity and diagnostic accuracy of "color spots" compared to MSCT were 95.3%, 68.0% and 91.8%, respectively. The "color-spot" showed a greater correlation to CT (V(index)=0.655; p<0.0001) than extrahepatic criteria (V=0.317). In 20/29 (69%) subjects, echo-color-Doppler, confirmed by CT, identified the third criterion for definite HHT diagnosis. CONCLUSIONS: Intrahepatic criteria was superior to extrahepatic criteria for identification of HAVMs. A new Doppler parameter ("color-spots") with an optimal accuracy for detecting HAVMs is proposed for easy periodic screening of HHT patients.

Dynamical quorum sensing: Population density encoded in cellular dynamics.

Mutual synchronization by exchange of chemicals is a mechanism for the emergence of collective dynamics in cellular populations. General theories exist on the transition to coherence, but no quantitative, experimental demonstration has been given. Here, we present a modeling and experimental analysis of cell-density-dependent glycolytic oscillations in yeast. We study the disappearance of oscillations at low cell density and show that this phenomenon occurs synchronously in all cells and not by desynchronization, as previously expected. This study identifies a general scenario for the emergence of collective cellular oscillations and suggests a quorum-sensing mechanism by which the cell density information is encoded in the intracellular dynamical state.