A multi-substrate screening approach for the identification of a broadly applicable Diels-Alder catalyst Kim, Hyejin; Gerosa, Gabriela Guillermina; Aronow, Jonas; Kasaplar, Pinar; Ouyang, Jie; Lingnau, Julia B.; Guerry, Paul; Farès, Christophe; List, Benjamin When developing a synthetic methodology, chemists generally optimize a single substrate and then explore the substrate scope of their method. This approach has led to innumerable and widely-used chemical reactions. However, it frequently provides methods that only work on model substrate-like compounds. Perhaps worse, reaction conditions that would enable the conversion of other substrates may be missed. We now show that a different approach, originally proposed by Kagan, in which a collection of structurally distinct substrates are evaluated in a single reaction vessel, can not only provide information on the substrate scope at a much earlier stage in methodology development, but even lead to a broadly applicable synthetic methodology. Using this multi-substrate screening approach, we have identified an efficient and stereoselective imidodiphosphorimidate organocatalyst for scalable Diels?Alder reactions of cyclopentadiene with different classes of α,β-unsaturated aldehydes.

Antecedentes de conservación y turismo en áreas naturales protegidas provinciales de Río Negro (Argentina); Conservation and tourism background in protected natural areas of Río Negro (Argentina) province Vejsbjerg, Laila El objetivo fue identificar los cambios en el tiempo del concepto de conservación y el rol del turismo en áreas naturales protegidas (ANPs), bajo jurisdicción yadministración de la provincia de Río Negro. Como resultado se diferenciaroncinco sub-períodos. Se concluyó: 1) En las zonas turísticas atlántica y andina lasANPs se integraron a proyectos turísticos intra e inter provinciales, aunque lasANPs de las zonas Alto Valle y Línea Sur tienen una escasa integración a circuitosextra-locales y su rol no es claro en el territorio del turismo; 2) Si bien endependencias provinciales de Ambiente ha habido una tendencia hacia una gobernanza estatal con co-manejo en el sector turístico privado existe un bajonivel de conocimiento de estas ANPs.; The aim was to identify changes over time regarding the notion of conservation and the role that tourism plays in natural protected areas (NPAs) under the jurisdiction and administration of the Río Negro province. As a result, five periods were differentiated. It was concluded that: 1) in the Atlantic and Andean tourist zones, NPAs are integrated with intra- and inter-provincial tourism projects, although the NPAs of Alto Valle and Línea Sur areas have little integration with extra-local circuits, and their role is not clear in the tourism territory; 2) while there has been a tendency towards state governance with co-management in provincial environmental departments in the private tourist sector has a low level of knowledge of these NPAs.

The role of an invader in its native range: could differential grazing by apple snails structure the submersed macrophytes assemblages in Southern Pampas (Argentina)? Manara, Enzo; Maldonado, Mara Anahí; Martín, Pablo Rafael Apple snails are renowned for their strong impacts on aquatic vegetation and ecosystem function in invaded regions but the existing knowledge on their role in aquatic ecosystems and communities in their native range is scarce. The variation in palatability of five submersed macrophytes, the preference of Pomacea canaliculata for them and the potential effects of its differential grazing on macrophyte assemblages in Southern Pampas were investigated. In no-choice trials, macrophytes showed differences in palatability that were correlated to physical defences and not to nutritional values. In free-choice trials, preference was consistent with the palatability ranking. In a mesocosms experiment, Chara contraria and Zannichellia palustris were totally eradicated by apple snails, the coverage of Stuckenia striata increased only when they were absent and Ludwigia peploides and Myriophyllum quitense were not affected. The live biomass of Z. palustris, S. striata and M. quitense was reduced by apple snails. Total live and dead biomasses were lower, and chlorophyll-a concentrations higher, in the mesocosms with apple snails. Our results indicate that P. canaliculata has a keystone role in its native range and that its differential grazing could shape the structure and composition of submersed vegetation and promote shifts to turbid-water states or maintain them.

Modern plains vizcacha (Lagostomus maximus, Chinchillidae, Rodentia) as a bone accumulating agent in the Argentine Pampas: Application to the study of fossiliferous sites Tomassini, Rodrigo Leandro; Montalvo, Claudia Inés; Fernández Jalvo, Yolanda; Garrone, Mariana Carolina; Kin, Marta Susana Lagostomus maximus (Rodentia, Chinchillidae), or Plains vizcacha, is a caviomorph rodent that inhabits semi-arid grasslands and desert scrub of central and northern Argentina, southern Paraguay and southeastern Bolivia. A particular behavior of the Plains vizcacha is the collection and transport of bones, dried dung and branches, among other objects, which are accumulated near the vizcacheras entrances. A bone concentration, originated in active vizcacheras of the southwestern Buenos Aires Province (Argentina), was studied from a taphonomic point of view for one year. The obtained results reflect that Plains vizcacha represents an important bone accumulating agent in the Argentine Pampas, and it is capable of producing large concentrations. Moreover, their vizcacheras act as natural traps that may favor the accumulation and preservation of the bone remains. The information obtained through this actualistic study provides new information on the ecology of this rodent and, in turn, introduces a framework of reference for the identification of similar concentrations in the fossil record.

Statistics of incompressible hydrodynamic turbulence: An alternative approach Andrés, Nahuel; Banerjee, Supratik Using a recent alternative form of the Kolmogorov-Monin exact relation for fully developed hydrodynamics (HD) turbulence, the incompressible energy cascade rate is computed. Under this current theoretical framework, for three-dimensional (3D) freely decaying homogeneous turbulence, the statistical properties of the fluid velocity (u), vorticity (ω= ×u), and Lamb vector (L=ω×u) are numerically studied. For different spatial resolutions, the numerical results show that can be obtained directly as the simple products of two-point increments of u and L, without the assumption of isotropy. Finally, the results for the largest spatial resolutions show a clear agreement with the cascade rates computed from the classical four-thirds law for isotropic homogeneous HD turbulence.

Zeta potential changes of Saccharomyces cerevisiae during fermentative and respiratory cycles Lavaisse, Lucía María; Hollmann, Axel; Nazareno, Mónica Azucena; Disalvo, Edgardo Anibal Saccharomyces cerevisiae is a type of yeast, widely used in diverse biotechnological food-beverage processes. Although the performance of an industrial fermentation process depends largely on the number of cells, it is necessary to consider the physiological state of the cultures. In this context, the aim of this study was to determine in a yeast culture how factors such as growth conditions affect surface properties at the different growth stages. Our results show that, S. cerevisiae spp. exhibits different zeta potential mean values along the exponential, post-diauxic and stationary growth phases. In addition, there were differences depending on whether they are in aerobic or anaerobic conditions. When the effect of pH on the media was studied, a different dependence of zeta potential at each stage reveals that in the living cells the surface potential depends on the interaction between secreted acids and the constituents of the surfaces, according to the growth conditions. In order to have a view at the cellular level, the zeta potential on individual cells by optical microscopy has been determined at different stages of culture in aerobic and anaerobic conditions. This single-cell method allows for the identification and following of the development of different cell subpopulations during each growth stage. Furthermore, the behavior of the dead cells provided evidence to relate the large negatively charged population with cell wall damage. Overall, the results obtained in the present work represent an important milestone for a novel application of zeta potential technique on yeast.

Retrieving shallow shear-wave velocity profiles from 2D seismic-reflection data with severely aliased surface waves Onnis, Luciano Emanuel; Osella, Ana Maria; Carcione, Jose M. The inversion of surface-wave phase-velocity dispersion curves provides a reliable method to derive near-surface shear-wave velocity profiles. In this work, we invert phase-velocity dispersion curves estimated from 2D seismic-reflection data. These data cannot be used to image the first 50 m with seismic-reflection processing techniques due to the presence of indistinct first breaks and significant NMO-stretching of the shallow reflections. A surface-wave analysis was proposed to derive information about the near surface in order to complement the seismic-reflection stacked sections, which are satisfactory for depths between 50 and 700 m. In order to perform the analysis, we had to overcome some problems, such as the short acquisition time and the large receiver spacing, which resulted in severe spatial aliasing. The analysis consists of spatial partitioning of each line in segments, picking of the phase-velocity dispersion curves for each segment in the f-k domain, and inversion of the picked curves using the neighborhood algorithm. The spatial aliasing is successfully circumvented by continuously tracking the surface-wave modal curves in the f-k domain. This enables us to sample the curves up to a frequency of 40 Hz, even though most components beyond 10 Hz are spatially aliased. The inverted 2D VS sections feature smooth horizontal layers, and a sensitivity analysis yields a penetration depth of 20–25 m. The results suggest that long profiles may be more efficiently surveyed by using a large receiver separation and dealing with the spatial aliasing in the described way, rather than ensuring that no spatially aliased surface waves are acquired.

Long-term changes on estuarine ciliates linked with modifications on wind patterns and water turbidity López Abbate, María Celeste; Molinero, Juan Carlos; Perillo, Gerardo Miguel E.; Barria, Maria Sonia; Pettigrosso, Rosa Elsa; Guinder, Valeria Ana; Uibrig, Román Armando; Berasategui, Anabela Anhi; Vitale, Alejandro José; Marcovecchio, Jorge Eduardo; Hoffmeyer, Monica Susana Planktonic ciliates constitute a fundamental component among microzooplankton and play a prominent role in carbon transport at the base of marine food webs. How these organisms respond to shifting environmental regimes is unclear and constitutes a current challenge under global ocean changes. Here we examine a multiannual field survey covering 25 years in the Bahía Blanca Estuary (Argentina), a shallow, flood-plain system dominated by wind and tidal energy. We found that the estuary experienced marked changes in wind dominant regimes and an increase in water turbidity driven from the joint effect of persistent long-fetch winds and the indirect effect of the Southern Annular Mode. Along with these changes, we found that zooplankton components, i.e. ciliates and the dominant estuarine copepod Acartia tonsa, showed a negative trend during the period 1986–2011. We showed that the combined effects of wind and turbidity with other environmental variables (chlorophyll, salinity and nutrients) consistently explained the variability of observed shifts. Tintinnids were more vulnerable to wind patterns and turbidity while showed a loss of synchrony with primary productivity. Water turbidity produced a dome-like pattern on tintinnids, oligotrichs and A. tonsa, implying that the highest abundance of organisms occurred under moderate values (∼50 NTU) of turbidity. In contrast, the response to wind patterns was not generalizable probably owing to species-specific traits. Observed trends denote that wind-induced processes in shallow ecosystems with internal sources of suspended sediments, are essential on ciliate dynamics and that such effects can propagate trough the interannual variability of copepods.

Optimization of bromelain isolation from pineapple byproducts by polysaccharide complex formation Campos, Débora A.; Coscueta, Ezequiel Ricardo; Woitovich Valetti, Nadia; Pastrana Castro, Lorenzo M.; Domínguez Teixeira, José Mario; Picó, Guillermo Alfredo; Pintado, Maria Manuela A simple method for bromelain extraction from industrial pineapple residues (stems and peels) was developed and optimized through factorial experimental design. The developed methodology, based on precipitation with carrageenan, represents an alternative to the use of organic solvents and inorganic salts (common industrial precipitation) and allows achieving extracts with high bromelain purity. High recovery yield – 80–90% - of active bromelain was obtained for both crude juices (stems and peels) making possible to obtain ca. 0.3 g of bromelain from 100 g of pineapple byproducts using a low polysaccharide concentration (0.2–0.3% w/v).

Thymol supplementation effects on adrenocortical, immune and biochemical variables recovery in Japanese quail after exposure to chronic heat stress Nazar, Franco Nicolas; Videla, Emiliano Ariel; Marin, Raul Hector Chronic heat stress (CHS) exposure negatively impairs avian' immunoneuroendocrine interplay. Thymol has shown several bioactive properties including antioxidant, bactericidal, antifungal and gamma-aminobutyric acid modulator activities. Indeed, supplementation with thymol has been used with positive effects on poultry production and immune-related variables. This study evaluates whether a thymol dietary supplementation can be used as a new functional feed strategy to mitigate CHS deleterious effects on endocrine, biochemical and immune-related variables. Starting at 100 days of age, 24 fully adult Japanese quail were fed with a diet supplemented with thymol (≈80 mg/quail per day) and other 24 quail remained non-supplemented (control diet). Between 119 and 127 days of age, half of the quail within those groups were submitted to a CHS by increasing environmental temperature from 24°C to 34°C during the light phase and the other half remained at 24°C (non-stressed controls). A period of 3 days after CHS ended (during the recovery period), corticosterone, albumin, total proteins and globulins and glucose concentrations, inflammatory response, antibody production and heterophil to lymphocyte (H/L) ratio were assessed. No differences between groups were found in basal corticosterone concentrations. Total proteins, total globulins and glucose concentrations were found elevated in the previously CHS group compared with their control counterparts. Regardless of the previous CHS exposure, thymol supplementation increased albumin concentrations and inflammatory responses and decreased antibody titers. An interaction between thymol supplementation and prior CHS exposure was found on the H/L ratio. Quail previously exposed to CHS and supplemented with thymol showed similar H/L values than their control non-stressed counterparts, suggesting that thymol has a stress preventive effect on this variable. The present findings together with the already reported thymol bioactive properties, suggest that feed supplementation with this compound could be a useful strategy to help overcoming some of the CHS induced alterations.

The effect of a saturated kink on the dynamics of tungsten impurities in the plasma core Ferrari, Hugo Emilio; Farengo, Ricardo; Clauser, Cesar Fernando We studied the effect of saturated kink like instabilities on the redistribution of W impurities. A numerical code that follows the exact trajectories of the impurity ions in the total fields and includes collisions was employed. The code is written in CUDA C and runs in graphical processing units, allowing simulations with a large number of particles with modest resources.The total electric and magnetic fields are calculated as the sum of a simple analytical equilibrium (large aspect ratio, circular cross section) plus the fields of the kink mode. Our simulations show that when the W ions have a thermal velocity distribution, with zero mean velocity, the kink hasno effect on the W density. However, when we include the plasma rotation and the drag on the impurities, the kink can affect the W density. When the average passing frequency of the W ions is similar to the frequency of the kink mode, the expulsion of W ions from the plasma core is maximum and the W density profile shows a hollow structure. This could have implications for the mitigation of W accumulation.

Vertical dispersion of Lagrangian tracers in fully developed stably stratified turbulence Sujovolsky, Nicolás Eduardo; Mininni, Pablo Daniel We study the effect of different forcing functions and of the local gradient Richardson number Rig on the vertical transport of Lagrangian tracers in stably stratified turbulence under the Boussinesq approximation and present a wave and continuous-time random-walk model for single- and two-particle vertical dispersion. The model consists of a random superposition of linear waves with their amplitude, based on the observed Lagrangian spectrum of vertical velocity, and a random-walk process to capture overturning that depends on the statistics of Rig among other Eulerian quantities. The model is in good agreement with direct numerical simulations of stratified turbulence, where single- and two-particle dispersion differ from the homogeneous and isotropic case. Moreover, the model gives insight into the mixture of linear and nonlinear physics in the problem, as well as on the different processes responsible for vertical turbulent dispersion.

Electronic and magnetic properties of the adsorption of As harmful species on zero-valent Fe surfaces, clusters and nanoparticules Alfonso Tobón, Leslie Lissette; Fuente, Silvia Andrea; Branda, Maria Marta A systematic theoretical study of the adsorption of H3AsO3 and H3AsO4 acids on Fe nanoparticles was carried out using the Density Functional Theory (DFT). Different sizes of zero-valent iron particles and also the two most stable surfaces of Fe, (1 1 1) and (1 1 0), were studied by characterizing the type of interaction present between the substrates and the adsorbates. Arsenic acid (H3AsO4) is spontaneously reduced in both extended surfaces of iron, producing arsenious acid and oxidizing the metal surface. Arsenious acid (H3AsO3) completely decomposes into (AsOH)(OH)(OH) fragments on the smallest particles, Fe32 and Fe59, but also on the (1 1 1) surface. However, on greater particles (NP80 and NP113) and on the (1 1 0) surface, H3AsO3 retains its initial free configuration and is joined to the surface through both atoms, As and O. Large dispersion components of the adsorption energy were observed when the acids interact with the substrates without decomposition. From a Bader analysis of the atomic charges, important charge transfers were found. Both the As and the interacting Fe atom are slightly reduced on the (1 1 0) surface and NP80. However, the four nearest neighboring irons are oxidized because of the interaction with H3AsO3. In the case of the Fe32 cluster, where this acid is totally broken, all the interacting Fe atoms are oxidized. A significant decrease of the magnetic moment was found for the Fe atom that interacts with H3AsO3. This fact was confirmed with the diminution of the spin up population and the increase of the spin down population observed in the PDOS of d states after the acid was bond to the iron substrates. Besides, important changes in the PDOS have point out the central role of the iron d orbitals on the reactivity of the surface and nanoparticles, but also an important participation of the p ones in the case of the cluster Fe32.

Maternally inherited Leigh syndrome detected by Multiplex ligation-dependent probe amplification Mayorga, Lía; Cueto, Juan Agustin; Correa, Adriana P.; Guillamondegui, María J.; Loos, Mariana; Araoz, Verónica H.; Laurito, Sergio Roberto; Roqué, María Leigh syndrome (LS) is a mitochondrial progressive encephalopathy characterized by bilateral symmetric necrotic lesions of the central nervous system. Maternally inherited Leigh Syndrome (MILS) represents 10–20% of LS. Mutations in MT-ATP6 are the most common, being m.8993T > C/G the classical mutations. Molecular diagnosis for mitochondrial diseases is always a challenge and Multiplex ligationdependent probe amplification (MLPA) of mitochondrial DNA can be an initial test for molecular diagnosis, although it is not widely used. We present a MILS patient in which MLPA was able to detect the common m.8993 T > G mutation and serve as a first approach for the definite molecular diagnosis.

Exploring soybean management options for environments with contrasting water availability Di Mauro, Guido; Borras, Lucas; Rugeroni, Pablo; Rotundo, José Luis Soybean is commonly cultivated under rainfed conditions being water availability the main constraint. We evaluated the performance of different managements under contrasting water availability to test possible trade-offs among managements, and to determine physiological variables explaining these yield differences. Four treatments were designed through specific combinations of cultivar, row spacing and stand density. They were classified as stress tolerance or yield potential strategies and were evaluated under two contrasting water availability treatments. Treatments ranged from 349 to 954 mm total water availability. Water stress treatments yielded 72% and 59% of the well-watered treatment each year, similar to frequent soybean water stress levels for our production region. Management treatments showed significant yield differences (p < 0.05), but the management × water availability interaction did not (p = 0.42). No management option helped reduce negative water stress effects. Highest yields were achieved using 0.25 m row spacing, a stand density of 60 pl per m 2 , and a high yield potential genotype. Yield variations were explained by differences in harvested seeds per unit area (R 2  = 0.75; p < 0.001) and total N uptake at maturity (R 2  = 0.93; p < 0.001) across environments. Because management strategies specifically tailored to cope with water shortages showed limited value, farmers need to target yield potential management options.

Evaluation of differential cross sections using classical two-active electron models for He Bachi, Nicolás; Otranto, Sebastián Differential cross sections for charge-exchange and single and double electronic emission in collisions of protons with He atoms at intermediate impact energies are theoretically evaluated by means of two classical trajectory Monte Carlo methods. These models incorporate momentum-dependent terms to the Hamiltonian in order to avoid the classical autoionization of He. The theoretical results for single capture and single ionization are compared to available experimental data. The role of the electron–electron correlation effects in double ionization processes is analyzed by inspecting the angular and energetic dependence of the electronic emission spectra at different impact energies.

Identification of the tension force in cables with insulators Rango, Bruno Javier; Serralunga, Fernando J.; Piovan, Marcelo Tulio; Ballaben, Jorge Sebastian; Rosales, Marta Beatriz The present paper explores two approaches which, based on the measurement of the two first natural frequencies, allow the identification of the tension force in cables with insulators. For this purpose, the nonlinear mathematical model of the mechanical system and its Finite Element discretization are firstly stated. Besides, free-vibrations experiments on both a laboratory and a real-scale simulated configuration of cables with insulators are performed in order to derive their frequency response. During the laboratory experiments, a vision-based methodology is implemented for the register of the time series displacements of the cable. On this basis, a Bayesian approach is first addressed. In this framework, the cable tension is regarded as a random variable and the Bayes rule is applied to combine the experimental natural frequencies with the prior information about the random variable to derive the posterior distribution of the tension force. The Markov Chain Monte CarloMetropolis Hastings algorithm is implemented for the evaluation of the posterior distribution. On the other hand, a heuristic approach is proposed through the implementation of an Artificial Neural Network (ANN) as an inverse model between the parameters of the cable—including the natural frequencies—and its tension force. The training patterns are obtained from computational simulations of different cable configurations. The experimental natural frequencies are then applied to the trained ANNs to infer the tension force of the laboratory and real-scale configurations. Both approaches provide estimates of the tension force within admissible error margins.

Early-warning signals of individual tree mortality based on annual radial growth Cailleret, Maxime; Dakos, Vasilis; Jansen, Steven; Robert, Elisabeth M. R.; Aakala, Tuomas; Amoroso, Mariano Martin; Antos, Joe A.; Bigler, Christof; Bugmann, Harald; Caccianaga, Marco; Camarero, Jesus Julio; Cherubini, Paolo; Coyea, Marie R.; Cufar, Katarina; Das, Adrian J.; Davi, Hendrik; Gea Izquierdo, Guillermo; Gillner, Sten; Haavik, Laurel J.; Hartmann, Henrik; Heres, Ana Maria; Hultine, Kevin R.; Janda, Pavel; Kane, Jeffrey M.; Kharuk, Viachelsav I.; Kitzberger, Thomas; Klein, Tamir; Levanic, Tom; Linares, Juan Carlos; Lombardi, Fabio; Mäkinen, Harri; Mészáros, Ilona; Metsaranta, Juha M.; Oberhuber, Walter; Papadopoulos, Andreas; Petritan, Any Mary; Rohner, Brigitte; Sangüesa Barreda, Gabriel; Smith, Jeremy M.; Stan, Amanda B.; Stojanovic, Dejan B.; Suarez, Maria Laura; Svoboda, Miroslav; Trotsiuk, Volodymyr; Villalba, Ricardo; Westwood, Alana R.; Wyckoff, Peter H.; Martínez Vilalta, Jordi Tree mortality is a key driver of forest dynamics and its occurrence is projected to increase in the future due to climate change. Despite recent advances in our understanding of the physiological mechanisms leading to death, we still lack robust indicators of mortality risk that could be applied at the individual tree scale. Here, we build on a previous contribution exploring the differences in growth level between trees that died and survived a given mortality event to assess whether changes in temporal autocorrelation, variance, and synchrony in time-series of annual radial growth data can be used as early warning signals of mortality risk. Taking advantage of a unique global ring-width database of 3065 dead trees and 4389 living trees growing together at 198 sites (belonging to 36 gymnosperm and angiosperm species), we analyzed temporal changes in autocorrelation, variance, and synchrony before tree death (diachronic analysis), and also compared these metrics between trees that died and trees that survived a given mortality event (synchronic analysis). Changes in autocorrelation were a poor indicator of mortality risk. However, we found a gradual increase in inter-annual growth variability and a decrease in growth synchrony in the last ∼20 years before mortality of gymnosperms, irrespective of the cause of mortality. These changes could be associated with drought-induced alterations in carbon economy and allocation patterns. In angiosperms, we did not find any consistent changes in any metric. Such lack of any signal might be explained by the relatively high capacity of angiosperms to recover after a stress-induced growth decline. Our analysis provides a robust method for estimating early-warning signals of tree mortality based on annual growth data. In addition to the frequently reported decrease in growth rates, an increase in inter-annual growth variability and a decrease in growth synchrony may be powerful predictors of gymnosperm mortality risk, but not necessarily so for angiosperms.

Improvement in poly(ɛ-caprolactone) bio-activity: Structural characterization and in vitro assessment Ninago, Mario Daniel; Ciolino, Andrés Eduardo; Villar, Marcelo Armando Model PCL homopolymers (anionic polymerization) were synthetized and chemically functionalized with anhydrides to improve their bio-activity. Modified polyesters were used to fabricate highly porous PCL membranes by leaching technique, reaching porosities values up to 86.1%. Microstructural characterization revealed that chemical modification did not affect thermal properties and mechanical stabilities of PCL membranes. In vitro assays were carried out by soaking samples in simulated body fluid (SBF) solution. By SEM-EDX and TGA analyses, it was observed thatmodified polyesters exhibited a hydroxyapatite layer over polymeric surfaces, with calcium/phosphorous ratio of 1.58, close to the value reported by literature for hard tissue.

High density lipoprotein is an inappropiate substrate for hepatic lipase in postmenopausal women Zago, Valeria; Miksztowicz, Verónica Julieta; Cacciagiú, Leonardo D.; Basilio, Francisco; Berg, Gabriela Alicia; Schreier, Laura Ester Background HDL antiatherogenic effects would not only depend on its concentration but also on its biological quality. Hepatic lipase (HL) action on HDL acts in one of the last steps of reverse cholesterol transport. Cardiovascular risk increases after menopause, however HDL does not decrease even when HL is increased. We evaluated HDL capacity as a substrate of HL in healthy postmenopausal women (PMW). Methods We studied 20 PMW (51–60 y) and 20 premenopausal (PreMW) (26–40 y). In fasting serum, lipid–lipoprotein profile and HDL composition were assessed. Optimal assay conditions for HDL/HL ex vivo incubation were established. Increasing HDL–triglyceride concentrations (0.015 to 0.20 mmol/l) were incubated with post-heparin plasma obtained from a single healthy donor as a source of HL. Free fatty acids were measured and kinetic parameters calculated: Km(app), inverse to enzyme affinity, and Vmax. Results HDL composition in PMW exhibits triglyceride enrichment (p < 0.001). Kinetic analysis revealed higher Km(app) in PMW [130 (40–380) vs 45 (20–91) mmol/l, p < 0.0001)] correlating directly with HDL–triglycerides (r = 0.7, p = 0.0001). Catalytic efficiency, Vmax/Km(app) was reduced when compared to controls (p = 0.0001). Conclusion Triglyceride-enriched HDL from PMW constitutes a poor substrate for HL suggesting that this particle may not exert efficiently its antiatherogenic function, regardless of plasma concentration.