Old divergence and restricted gene flow between torrent duck ( Merganetta armata ) subspecies in the Central and Southern Andes

Aim: To investigate the structure and rate of gene flow among populations of habitat‐specialized species to understand the ecological and evolutionary processes underpinning their population dynamics and historical demography, including speciation and extinction.Location: Peruvian and Argentine Andes.Taxon: Two subspecies of torrent duck (Merganetta armata).Methods: We sampled 156 individuals in Peru (M. a. leucogenis; Chillón River, n = 57 and Pachachaca River, n = 49) and Argentina (M. a. armata; Arroyo Grande River, n = 33 and Malargüe River, n = 17), and sequenced the mitochondrial DNA (mtDNA) control region to conduct coarse and fine‐scale demographic analyses of population structure. Additionally, to test for differences between subspecies, and across genetic markers with distinct inheritance patterns, a subset of individuals (Peru, n = 10 and Argentina, n = 9) was subjected to partial genome resequencing, obtaining 4,027 autosomal and 189 Z‐linked double‐digest restriction‐associated DNA sequences.Results: Haplotype and nucleotide diversities were higher in Peru than Argentinaacross all markers. Peruvian and Argentine subspecies showed concordant species‐level differences (ΦST mtDNA= 0.82;ΦST autosomal = 0.30;ΦST Z chromosome = 0.45),including no shared mtDNA haplotypes. Demographic parameters estimated formtDNA using IM and IMa2 analyses, and for autosomal markers using ∂a∂i (isolation‐with‐migration model), supported an old divergence (mtDNA = 600,000 years before present (ybp), 95% HPD range = 1.2 Mya to 200,000 ybp; and autosomal ∂a∂i = 782,490 ybp), between the two subspecies, characteristic of deeply divergedlineages. The populations were well‐differentiated in Argentina but moderately differentiated in Peru, with low unidirectional gene flow in each country.Main conclusions: We suggest that the South American Arid Diagonal was preexisting and remains a current phylogeographic barrier between the ranges of the two torrent duck subspecies, and the adult territoriality and breeding site fidelity to the rivers define their population structure.Fil: Alza, Luis. University of Alaska; Estados Unidos. University of Miami. Department of Biology; Estados Unidos. División de Ornitología. Centro de Ornitología y Diversidad; PerúFil: Lavretsky, Philip. University of Texas at El Paso; Estados UnidosFil: Peters, Jeffrey L.. Wright State University; Estados UnidosFil: Cerón, Gerardo. Universidad Nacional del Comahue. Centro Regional Universitario Bariloche. Departamento de Zoología. Laboratorio de Parasitología; ArgentinaFil: Smith, Matthew. University of Alaska; Estados UnidosFil: Kopuchian, Cecilia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Centro de Ecología Aplicada del Litoral. Universidad Nacional del Nordeste. Centro de Ecología Aplicada del Litoral; Argentina. Museo Argentino de Ciencias Naturales, División Ornitología,; ArgentinaFil: Astié, Andrea Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Investigaciones de las Zonas Áridas. Provincia de Mendoza. Instituto Argentino de Investigaciones de las Zonas Áridas. Universidad Nacional de Cuyo. Instituto Argentino de Investigaciones de las Zonas Áridas; ArgentinaFil: McCracken, Kevin G.. División de Ornitología. Centro de Ornitología y Diversidad; Perú. University of Miami. Department of Biology; Estados Unidos. University of Miami; Estados Unidos. University of Alaska; Estados Unido

High sodium diet and circulating digitalis-like compound in the rat

The effects of a high salt diet (8% NaCl) on blood pressure and intra-erythrocytic Na+ content were studied in Wistar rats. The ability of the plasma to inhibit the renal Na+,K+-ATPase activity and to cross-react with digoxin antibodies was also investigated. After 1 week, neither systolic blood pressure nor intra-erythrocytic Na+ content were modified, but plasma extracts slightly inhibited renal Na+,K+-ATPase (70.9 +/- 1.7 versus 76.3 +/- 2.1 mumol Pi/mg per h, P = 0.05). After 2 weeks, the plasma inhibitory activity, systolic blood pressure and intra-erythrocytic Na+ content were higher than corresponding values in control animals (65.5 +/- 1.6 versus 79.1 +/- 2.8 mol Pi/mg per h, P less than 0.001; 132 +/- 2 versus 114 +/- 4 mmHg, P less than 0.001, and 4.95 +/- 0.32 versus 3.81 +/- 0.36 mmol/l cells, P less than 0.05, respectively). After 3 months, the plasma digoxin-like immunoreactivity and its ability to inhibit the Na+ pump were elevated (68.7 +/- 7.9 versus 48.2 +/- 5.4 pg/ml, P less than 0.02; 57.8 +/- 1.8 versus 72.9 +/- 1.8 mumol Pi/mg per h, P less than 0.001, respectively) whereas intra-erythrocytic Na+ content had returned to control levels. The results demonstrated that this high salt intake led to simultaneous increases in systolic blood pressure and in the activity of a digitalis-like compound present in plasma. The inhibition of Na+,K+-ATPase was correlated with systolic blood pressure and digoxin-like immunoreactivity (r = 0.569, n = 76, P less than 0.001 and r = 0.414, n = 34, P less than 0.02, respectively).(ABSTRACT TRUNCATED AT 250 WORDS

Methods to simplify diet and food life cycle inventories: Accuracy versus data-collection resources

The number of\ua0Life\ua0Cycle\ua0Assessment (LCA) studies on foods and diets steadily increases. However, due to lack of\ua0data\ua0on\ua0food\ua0products as well as time and\ua0resource\ua0constraints, many of these studies ignore part of the system (e.g. cooking and waste in the household), which may lead to underestimating impacts greatly. This LCA study compared diets using six\ua0methods\ua0with different system boundaries; three of these are simplified\ua0methods\ua0we developed. The aim was to identify which\ua0method\ua0best optimizes\ua0data\ua0collection\ua0for\ua0life\ua0cycle\ua0inventories\ua0from cradle to human mouth of\ua0food\ua0products and diets. The principle behind the three simplified\ua0methods\ua0was that, for many foods and impact categories, the farm (or fishery) is the\ua0life\ua0cycle\ua0stage that contributes most to impacts. One average, one healthy and one vegetarian\ua0diet, each composed of up to 105 foods, were assessed. Climate change, cumulative energy demand, eutrophication, acidification and land occupation impacts were estimated. Recommendations are given on which\ua0methods, depending on study goals, offer the best trade-off among available\ua0resources\ua0(time, money, and knowledge), while providing the required robustness of results. Compared to a full LCA, simplified LCA\ua0methods\ua0can yield more accurate results at a lower cost of\ua0data\ua0collection

The 2.1 A structure of an elicitin-ergosterol complex: a recent addition to the Sterol Carrier Protein family.

Elicitins, produced by most of the phytopathogenic fungi of the genus Phytophthora, provoke in tobacco both remote leaf necrosis and the induction of a resistance against subsequent attack by various microorganisms. Despite the recent description of the three-dimensional crystal structure of cryptogein (CRY), the molecular basis of the interactions between Phytophthora and plants largely remains unknown. The X-ray crystal structure, refined at 2.1 A, of a ligand complexed, mutated CRY, K13H, is reported. Analysis of this structure reveals that CRY is able to encapsulate a ligand that induces only a minor conformational change in the protein structure. The ligand has been identified as an ergosterol by gas chromatographic analysis coupled with mass spectrometry analysis. This result is consistent with biochemical data that have shown that elicitins are a distinct class of Sterol Carrier Proteins (SCP). Data presented here provide the first structural description of the pertinent features of the elicitin sterol interaction and permit a reassessment of the importance of both the key residue 13 and the mobility of the omega loop for the accessibility of the sterol to the cavity. The biological implications thereof are discussed. This paper reports the first structure of a SCP/sterol complex

Correlations between plasma levels of an endogenous digitalis-like substance and haemodynamic parameters measured during cardiac catheterization

It has been postulated that one or more plasma digitalis-like compounds may play an important role in body fluid regulation and in essential hypertension, although very little is known about their possible role in general haemodynamics. We therefore measured plasma inhibition of human kidney Na+,K+-ATPase and plasma cross-reactivity with digoxin antibodies in 11 normotensive cardiopathic subjects admitted to our clinic for heart catheterization. Possible correlations with haemodynamic parameters were studied. Plasma digoxin-like activity correlated directly with left atrial pressure and with pulmonary circulation data. The ability of the plasma to inhibit Na+,K+-ATPase showed an inverse correlation with cardiac output and cardiac index. No correlations were found with any of the other parameters measured, notably systemic resistance, blood pressure and natriuresis. These findings suggest the presence of more than one substance sharing chemical properties with digitalis: (1) a substance cross-reacting with digoxin antibodies and dependent on pulmonary vascular congestion; and (2) a substance capable of inhibiting the Na+-K+ pump and present in large amounts in heart diseases with a reduced cardiac index

Investigation of the endogenous Na+-pump inhibitor in essential hypertension and blood volume expansion

The digitalis-like activities of plasma extracts from 108 patients and normal subjects were measured by their ability to compete with ouabain for binding to the digitalis sites of the Na+-pump. High levels were found in 18 of 54 untreated patients with moderate hypertension, 10 of 14 patients with end-stage renal failure and six patients with active acromegaly. These levels returned to control values after dialysis in the patients with renal insufficiency and high levels of the inhibitor, and after successful surgery and cobalt therapy in seven acromegalic patients. An increase in circulating Na+, K+-ATPase inhibitor was also found in rats after chronic sodium loading. These results indicate that levels of the circulating compound with digitalis-like properties do not result from high blood pressure but, rather, are related to blood volume and Na+ balance