Campagne BERYX 10 de pêche à la palangre de fond sur trois monts sous-marins du sud-est de la zone économique de Nouvelle-Calédonie. (N.O."Alis", 18 au 27 Août 1992)

BERYX 10 fut la dixième campagne d'une série consacrée à l'étude des ressources halieutiques des monts sous-marins situés au sud-est de la Nouvelle-Calédonie. 8 pêches furent réalisées sur les monts B, K et D avec une palangre de fond du même type que celle qui fut mise en oeuvre par le palangrier "Humboldt". Un total de 6000 hameçons fut mis à l'eau. La diversité des prises (16 espèces) fut du même ordre que celle des campagne précédentes de pêche à la palangre de fond. Le rendement moyen en #Beryx fut 11.9 kg / 100 hameçons. Les autres espèces bien représentées furent #Rexe ante furcata, #Etmopterus lucifer et #Squalus cf. #megalops$. Les prises firent l'objet de mensurations et de prélèvements (gonades et estomacs). 41 traits de filet à plancton furent effectués à des profondeurs comprises entre 25 et 350 m. L'utilisation d'une sonde CTD SEACAT PROFILER a permis d'obtenir une coupe de température et de salinité pour le mont K. (Résumé d'auteur

Effects of particle composition on thorium scavenging in the North Atlantic

Author Posting. © The Author(s), 2018. This is the author's version of the work. It is posted here under a nonexclusive, irrevocable, paid-up, worldwide license granted to WHOI. It is made available for personal use, not for redistribution. The definitive version was published in Geochimica et Cosmochimica Acta 233 (2018): 115-134, doi:10.1016/j.gca.2018.04.035.The dependence of thorium scavenging by particles on particle composition is examined at selected stations of the U.S. GEOTRACES North Atlantic Section (GA03). Scavenging is here described by the apparent, first-order rate constant of Th adsorption onto particles (k1), as estimated from an inversion of Th radioisotope and radioactive parent data. Our k1 estimates are regressed against particle phase data using two different models. Model I considers biogenic particles (POC+PIC+bSi), lithogenic particles, Mn (oxyhydr)oxides, and Fe (oxyhydr)oxides as regressors, and k1 as the regressand. Model II considers ln(POC+PIC+bSi), ln(lithogenic particles), ln(Mn (oxyhydr)oxides), and ln(Fe (oxyhydr)oxides) as regressors, and ln(k1) as the regressand, where ln() denotes the natural logarithm. Thus, models I and II posit that the effects of particle phases on k1 are, respectively, additive and multiplicative. These models are applied to three groups of stations: (i) all selected stations, (ii) stations west of theMauritanian upwelling region (“western stations”), and (iii) stations within that region (“eastern stations”). We find that model II appears to better describe the effect of particle composition on k1 than model I. Particle composition explains a larger fraction of the variance of k1 for the eastern stations (R2 = 0.60 for model I and 0.67 for model II) than for the western stations (R2 = 0.26 for model I and 0.39 for model II). When considering all stations, the variance of k1 explained by particle composition is intermediate (R2 = 0.50 for model I and 0.51 for model II). According to model II, the variance of k1 explained by particle composition is predominantly due to biogenic particles at the eastern stations and to Mn (oxyhydr)oxides at the western stations. Additionally, we find that particle composition does not explain a significantly different proportion of variance of k1 than particle concentration. It is thus concluded that, at our selected stations, (i) biogenic particles andMn (oxyhydr)oxides more strongly influence Th scavenging than any other phases considered, and (ii) particle composition and particle concentration have comparable effects on this process.We acknowledge the U.S. National Science Foundation for supporting this study (grant OCE-1232578) and the U.S. GEOTRACES North Atlantic section ship time, sampling, and data analysis

Campagne BERYX 5 de pêche à la palangre de fond sur deux monts sous-marins du sud-est de la zone économique de Nouvelle Calédonie (N.O. "Alis", 28 janvier - 6 février 1992)

BERYX 5 fut la cinquième campagne d'une série consacrée à l'étude des ressources halieutiques des monts sous-marins situés au sud-est de la Nouvelle Calédonie. 8 pêches furent réalisées sur les monts B et K avec une palangre de fond du même type que celle qui fut mise en oeuvre par le palangrier "Humboldt". Un total de 8000 hameçons fut mis à l'eau. La diversité des prises (15 espèces) fut du même ordre que celle des campagnes précédentes de pêche à la palangre de fond. Les rendements en #Beryx furent excellents sur le mont B. Les autres espèces bien représentées furent #Rexea antefurcata et #Centrophorus sp.$. Les prises firent l'objet de mensurations et de prélèvements (gonades et estomacs). La bathymétrie réalisée sur le mont K a mis en évidence une extension vers le sud. L'utilisation d'une sonde CTD DEACAT PROFILER a permis d'obtenir une coupe de température et de salinité pour le mont B. Il n'apparaît aucune modification majeure de la structure thermique. (Résumé d'auteur

Emergence of a new predator in the North Sea: evaluation of potential trophic impacts focused on hake, saithe, and Norway pout

During the last 15 years, northern European hake (Merluccius merluccius) has increased in abundance, and its spatial distribution has expanded in the North Sea region in correlation with temperature. In a context of global warming, this spatial shift could impact local trophic interactions: direct impacts may affect forage fish through modified predator–prey interactions, and indirect impacts may materialize through competition with other resident predators. For instance, North Sea saithe (Pollachius virens) spatial overlap with hake has increased while saithe spawning-stock biomass has decreased recently notwithstanding a sustainable exploitation. In this context, we investigated the range of potential impacts resulting from most recent hake emergence in the North Sea, with a particular focus on saithe. We carried out a multispecies assessment of North Sea saithe, using the Stochastic MultiSpecies (SMS) model. In addition to top-down processes already implemented in SMS, we built in the model bottom-up processes, relating Norway pout (Trisopterus esmarkii) abundance and saithe weight-at-age. We simulated the effects, on all North Sea species being considered but focusing on Norway pout and saithe, of combining different hake abundance trends scenarios with the inclusion of bottom-up processes in SMS. North Sea saithe FMSY was then evaluated in a multispecies context and contrasted with single-species value. The different scenarios tested revealed a negative impact of hake emergence on saithe biomass, resulting from an increase of predation pressure on Norway pout. These results confirm the competition assumption between saithe and hake in the North Sea and might partially explain the most recent decrease of saithe biomass. This study also highlighted that taking into account bottom-up processes in the stock assessment had a limited effect on the estimation of saithe FMSY which was consistent with single-species value

Redefining Single-Trial Memories in the Honeybee

Research on honeybee memory has led to a widely accepted model in which a single pairing of an odor stimulus with sucrose induces memories that are independent of protein synthesis but is unable to form protein-synthesis-dependent long-term memory (LTM). The latter is said to arise only after three or more pairings of odor and sucrose. Here, we show that this model underestimates the capacity of the bee brain to form LTMs after a unique appetitive experience. Using state-of-the art conditioning setups and individual-based analyses of conditioned responses, we found that protein-synthesis-dependent memories are formed already 4 h after the single conditioning trial and persist even 3 days later. These memories (4 h, 24 h, and 72 h) exhibit different dependencies on transcription and translation processes. Our results thus modify the traditional view of onetrial memories in an insect with a model status for memory research.Fil: Villar, María Eugenia. Université de Toulouse; Francia. Centre National de la Recherche Scientifique; Francia. Universite de la Mediterranee. Institut Universitaire de France; FranciaFil: Marchal, Paul. Université de Toulouse; Francia. Centre National de la Recherche Scientifique; Francia. Universite de la Mediterranee. Institut Universitaire de France; FranciaFil: Viola, Haydee Ana Maria. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Biología Celular y Neurociencia "Prof. Eduardo de Robertis". Universidad de Buenos Aires. Facultad de Medicina. Instituto de Biología Celular y Neurociencia; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Fisiología, Biología Molecular y Celular; ArgentinaFil: Giurfa, Martín. Université de Toulouse; Francia. Centre National de la Recherche Scientifique; Francia. Fujian Agriculture and Forestry University; Chin

Distinct expression and methylation patterns for genes with different fates following a single whole-genome duplication in flowering plants

For most sequenced flowering plants, multiple whole-genome duplications (WGDs) are found. Duplicated genes following WGD often have different fates that can quickly disappear again, be retained for long(er) periods, or subsequently undergo small-scale duplications. However, how different expression, epigenetic regulation, and functional constraints are associated with these different gene fates following a WGD still requires further investigation due to successive WGDs in angiosperms complicating the gene trajectories. In this study, we investigate lotus (Nelumbo nucifera), an angiosperm with a single WGD during the K–pg boundary. Based on improved intraspecific-synteny identification by a chromosome-level assembly, transcriptome, and bisulfite sequencing, we explore not only the fundamental distinctions in genomic features, expression, and methylation patterns of genes with different fates after a WGD but also the factors that shape post-WGD expression divergence and expression bias between duplicates. We found that after a WGD genes that returned to single copies show the highest levels and breadth of expression, gene body methylation, and intron numbers, whereas the long-retained duplicates exhibit the highest degrees of protein–protein interactions and protein lengths and the lowest methylation in gene flanking regions. For those long-retained duplicate pairs, the degree of expression divergence correlates with their sequence divergence, degree in protein–protein interactions, and expression level, whereas their biases in expression level reflecting subgenome dominance are associated with the bias of subgenome fractionation. Overall, our study on the paleopolyploid nature of lotus highlights the impact of different functional constraints on gene fate and duplicate divergence following a single WGD in plant

Kinetics of thorium and particle cycling along the U.S. GEOTRACES North Atlantic Transect

© The Author(s), 2017. This is the author's version of the work. It is posted here under a nonexclusive, irrevocable, paid-up, worldwide license granted to WHOI. It is made available for personal use, not for redistribution. The definitive version was published in Deep Sea Research Part I: Oceanographic Research Papers 125 (2017): 106-128, doi:10.1016/j.dsr.2017.05.003.The high particle reactivity of thorium has resulted in its widespread use in tracing processes impacting marine particles and their chemical constituents. The use of thorium isotopes as tracers of particle dynamics, however, largely relies on our understanding of how the element scavenges onto particles. Here, we estimate apparent rate constants of Th adsorption (k1), Th desorption (k−1), bulk particle degradation (β-1), and bulk particle sinking speed (w) along the water column at 11 open-ocean stations occupied during the GEOTRACES North Atlantic Section (GA03). First, we provide evidence that the budgets of Th isotopes and particles at these stations appear to be generally dominated by radioactive production and decay sorption reactions, particle degradation, and particle sinking. Rate parameters are then estimated by fitting a Th and particle cycling model to data of dissolved and particulate 228,230,234Th, 228Ra, particle concentrations, and 234,238U estimates based on salinity, using a nonlinear programming technique. We find that the adsorption rate constant (k1) generally decreases with depth across the section: broadly, the time scale 1/k1 averages 1.0 yr in the upper 1000 m and (1.4–1.5) yr below. A positive relationship between k1 and particle concentration (P) is found, i.e., , k1 ∝ Pb where b ≥ 1, consistent with the notion that k1 increases with the number of surface sites available for adsorption. The rate constant ratio, K = k1/(k-1 + β-1), which measures the collective influence of rate parameters on Th scavenging, averages 0.2 for most stations and most depths. We clarify the conditions under which K/P is equivalent to the distribution coefficient, KD, test that the conditions are met at the stations, and find that decreases with P, in line with a particle concentration effect (dKD/dP < 0). In contrast to the influence of colloids as envisioned by the Brownian pumping hypothesis, we provide evidence that the particle concentration effect arises from the joint effect of P on the rate constants for thorium attachment to, and detachment from, particles.We acknowledge the U.S. National Science Foundation for providing funding for this study (grant OCE-1232578) and for U.S. GEOTRACES North Atlantic section ship time, sampling, and data analysis. The U.S. NSF also supported the generation of 230Th data (OCE-0927064 to LDEO, OCE-O092860 to WHOI, and OCE-0927754 to UMN) and 228,234Th data (OCE-0925158 to WHOI)

Daily changes in the electric behavior of weakly electric fish naturally persist in constant darkness and are socially synchronized

Daily rhythms allow anticipation of changes and allocation of energy to better cope with predictable events. Rhythms in behavior result from a complex combination of physiological processes timed by the nervous system and synchronized with external information. We aimed to understand how rhythmic behaviors arise in nature, when weakly electric fish are exposed to cyclic environmental influences and social context. Gymnotus omarorum is a South American nocturnal pulse-type gymnotiform. Its electric behavior encodes information about species, sex and physiological state. The rate of emission of the electric organ discharge (EOD-BR) is modulated by exploratory activity and by physical and social environmental stimuli. We show that the EOD-BR increases during the night in the natural habitat even in individuals maintained in constant dark conditions. Locomotor activity is higher at night, however the nocturnal increase of EOD-BR still occurs in motionless fish, demonstrating an independent origin for the locomotor and electric components of exploratory behavior. When fish are observed in nature, social context exerts a synchronizing role on electric behavior. G. omarorum emerges as an exciting wild model for the study of daily rhythms arising in the complexity of the real world, integrating environmental, physical and social cues in the modulation of rhythmic behavior