Characterization of branch complexity by fractal analyses

9 páginas, 4 tablas, 3 figurasThe comparison between complexity in the sense of space occupancy (box-counting fractal dimension Dc and information dimension DI) and heterogeneity in the sense of space distribution (average evenness index J&d1; and evenness variation coefficient JCV) were investigated in mathematical fractal objects and natural branch structures. In general, increased fractal dimension was paired with low heterogeneity. Comparisons between branch architecture in Anthyllis cytisoides under different slope exposure and grazing impact revealed that branches were more complex and more homogeneously distributed for plants on northern exposures than southern, while grazing had no impact during a wet year. Developmental instability was also investigated by the statistical noise of the allometric relation between internode length and node order. In conclusion, our study demonstrated that fractal dimension of branch structure can be used to analyze the structural organization of plants, especially if we consider not only fractal dimension but also shoot distribution within the canopy (lacunarity). These indexes together with developmental instability analyses are good indicators of growth responses to the environment.Peer reviewe

Kinetic and functional properties of human mitochondrial phosphoenolpyruvate carboxykinase

The cytosolic form of phosphoenolpyruvate carboxykinase (PCK1) plays a regulatory role in gluconeogenesis and glyceroneogenesis. The role of the mitochondrial isoform (PCK2) remains unclear. We report the partial purification and kinetic and functional characterization of human PCK2. Kinetic properties of the enzyme are very similar to those of the cytosolic enzyme. PCK2 has an absolute requirement for Mn2+ ions for activity; Mg2+ ions reduce the Km for Mn2+ by about 60 fold. Its specificity constant is 100 fold larger for oxaloacetate than for phosphoenolpyruvate suggesting that oxaloacetate phosphorylation is the favored reaction in vivo. The enzyme possesses weak pyruvate kinase-like activity (kcat=2.7 s-1). When overexpressed in HEK293T cells it enhances strongly glucose and lipid production showing that it can play, as the cytosolic isoenzyme, an active role in glyceroneogenesis and gluconeogenesis

Plant-plant interactions scale up to produce vegetation spatial patterns: The influence of long- and short-term process

Vegetation spatial patterns emerge in response to feedback interactions between organisms and their environment, because of the redistribution of water and nutrients around the plant canopy or as a consequence of facilitation/competition interactions at the plant level, even in the absence of pre-existing substratum heterogeneities. It has been suggested that changes in vegetation spatial patterns are a signal of transition shift in ecosystems. Understanding the factors that lead to aggregated spatial patterns and control the transition to random distributions requires that environmental and species information is taken into account. In this study, we investigated the relative contributions of aridity (a long-term process), to which vegetation is adapted, and the area covered by bare soil (short-term process) to plant-plant associations and their contribution to aggregated spatial patterns. The study was conducted in a gradient of aridity ranging from that in subalpine grassland habitats in the Pyrenees and Sierra Nevada mountains to that in the semiarid steppes of Cabo de Gata and the middle Ebro Valley in Spain. We compared sites that differed in aridity and a geophysical feature (north- vs. south-facing slope). We observed that the relative contribution of aridity and bare soil to plant-plant facilitation and vegetation aggregation differed in subalpine and semiarid areas. Facilitation in subalpine habitats had a marked effect on aggregated spatial patterns, while aridity contributed to disruption of these patterns. Conversely, in semiarid habitats, the disruption of aggregated patterns was mainly promoted by an increase in bare soil area rather than in aridity. In semiarid habitats, the higher level of stress on south-facing slopes increased facilitation interactions relative to north-facing slopes, although this did not enhance the persistence of aggregated spatial patterns. We conclude that the use of aggregated spatial patterns as an indicator of ecosystem shift must distinguish and separately take account of long-term processes to which vegetation adapt, and short-term process

Association between competition and facilitation processes and vegetation spatial patterns in alpha steppes

11 páginas, 5 figuras, 3 tablas.-- El PDF del artículo es la versión post-print.In semiarid ecosystems, the self-organized spatial patterns of plants associated with catastrophic shifts can emerge from a variety of processes. In this study, on moderate slopes where Stipa tenacissima cover was high, the self-organization of some of the typical species of semiarid Mediterranean matorral (Phlomis purpurea, Sideritis oxteosylla, Helianthemum almeriense, and Brachypodium retusum) was negatively correlated with Stipa cover. The extent of Stipa cover did not affect desert pioneer species, such as Artemisia herba-alba, Fagonia cretica, and Launaea lanifera. On pronounced slopes, the self-organizing structure of brushwood vegetation did not vary predictably with the amount of Stipa cover. We examined the competition/facilitation processes associated with self-organizing patterns in the dwarf shrub (Phl. purpurea) and the half shrub (H. almeriense). The developmental stability of H. almeriense was positively correlated with Stipa cover, which was expected because they are associated species in this seral thyme brushwood community. Indeed, facilitation processes were manifested by the developmental stability increases under the Stipa canopy, particularly on high slope areas, where Stipa is less competitive. In Phl. purpurea, negative feedback processes from competition with Stipa were manifested where Stipa cover was high and on low slopes (developmental instability increased). In general, competition with Stipa on low slopes tended to decrease plant self-organization.We gratefully acknowledge support from the Spanish CICYT (Project REN2002-04668/GLO, Efectos de la fragmentación y uso del suelo en la conservación y dinámica de las zonas esteparias Mediterráneas).Peer reviewe

Developmental Instability and Fitness in Periploca laevigata Experiencing Grazing Disturbance

10 páginas, 4 figuras, 4 tablas.We investigated the sensitivity of developmental instability measurements (leaf fluctuating asymmetry, floral radial asymmetry, and shoot translational asymmetry) to a long‐standing natural stress (grazing) in a palatable tannin‐producing shrub (Periploca laevigata Aiton). We also assessed the relationship between these measures of developmental instability and fitness components (growth and floral production). Developmental instability, measured by translational asymmetry, was the most accurate estimator of a plant’s condition and, consequently, environmental stress. Plants with less translational asymmetry grew more and produced more flowers. Plants from the medium‐grazed population were developmentally more stable, as estimated by translational and floral asymmetry, than either more heavily or more lightly grazed populations. Leaf fluctuating asymmetry was positively correlated with tannin concentration. The pattern of internode growth also responded to grazing impact. Plants under medium to heavy grazing pressure accelerated early growth and consequently escaped herbivory later in the season, i.e., at the beginning of the spring, when grazing activity was concentrated in herbaceous plants. Periploca laevigata accelerated growth and finished growing sooner than in the other grazing treatment. Thus, its annual growth was more mature and less palatable later in the season when grazers typically concentrate on shrubs. The reduction of developmental instability under medium grazing is interpreted as a direct effect of grazing and not as the release from competition.The work was realized under the Desertification Risk Assessment in Silvopastoral Mediterranean Ecosystems (DRASME) collaborative research project. DRASME is funded by the European Community under its International Cooperation with Developing Countries Program, contract number ERBIC18‐CT98‐0392. The support from this program is gratefully acknowledged. We are grateful to Dr. T. Navarro and Dr. M. Vrahnakis for critically reading the manuscript and making helpful suggestions. David Navas and Antonio Gonzalez assigned the taxonomic identification of each species, for which we are very grateful. We thank Rosa Jimenez Ortega, Antonio Parra Perez, David Navas, and Antonio Gonzalez for collaborating with us in the collection of data.Peer reviewe

Spatial preferences and behavioural patterns of lambs during fattening in straw enriched pens

The study analyses spatial preferences and behavioural patterns of lambs during fattening in straw enriched pens. Lambs were allocated in three replicates with 12 lambs each and housed in 6x6 m pens partially divided in two equal areas with and without straw bedding. Each pen was video-recorded continuously from 8 am to 8 pm on days 1, 5, 7, 14, 21 and 28. The use of different pen areas and the behaviour of the lambs were evaluated and analysed. The use of the space was significantly higher (p<0.05) for the straw area, where there was also more resting and affiliative interactions (p<0.05). In the areas without straw, animals walked more, remained standing longer periods (p<0.05) and had more stereotypic and aggressive behaviour (p<0.05). The study demonstrated that, when given the choice between two areas with similar resources, lambs prefer straw bedding. Straw is suggested to promote affiliation improving the adaptation to the feedlot. This could be useful to convince system managers that the availability of straw is beneficial to lamb welfare

Effects of alternative bedding substrates on lamb welfare, productive performance, and meat quality during the finishing phase of fattening

The study analyzed the effect of using sawdust, cellulose, straw, and rice husk bedding on the welfare, performance and meat quality of lambs during the finishing phase of fattening. Ninety-six lambs (fed ad libitum with concentrate) were assigned to pens containing 1 of 4 bedding materials in groups of 12 for 14 days. Live weight and feed consumption were recorded to estimate daily gain and conversion index, and carcass and meat quality variables were measured. Stereotypies, exploratory interactions with bedding material, and agonistic and affiliative interactions between animals were recorded by continuous sampling techniques using video recording. The substrates affected behavior and stress response variables. There were more stereotypies and agonistic interactions at the beginning of the experiment in all treatments (P ≤ 0.05). The lambs fattened on cellulose bedding interacted more with the substrate throughout the finishing stage (P ≤ 0.05), where there were also more affiliative interactions (P ≤ 0.05). Stress levels were lower in lambs on straw, followed by cellulose. No significant differences in production or carcass and meat quality traits were observed between treatments. The results suggest that all substrates evaluated could be efficiently incorporated into the system as bedding material without affecting productivity or product quality

Myeloid cell deficiency of p38γ/p38δ protects against candidiasis and regulates antifungal immunity

Fundació la Marató de TV3 (GrantNumber(s): 20133431; Grant recipient(s): Ana Cuenda) Wellcome Trust (GrantNumber(s): 97377, 102705; Grant recipient(s): GORDON D. BROWN) Ministerio de Economía y Competitividad (GrantNumber(s): SAF2016-79792-R, SAF2014- 52009-R, SAF2013-45331-R; Grant recipient(s): Ana Cuenda, SUSANA ALEMANY) Medical Research Council (GrantNumber(s): MR/N006364/1; Grant recipient(s): GORDON D. BROWN) ERC Consolidator Grant (GrantNumber(s): 310372; Grant recipient(s): Mihai Netea)Peer reviewedPublisher PD

Hydrocarbon Contamination Decreases Mating Success in a Marine Planktonic Copepod

The mating behavior and the mating success of copepods rely on chemoreception to locate and track a sexual partner. However, the potential impact of the water-soluble fraction of hydrocarbons on these aspects of copepod reproduction has never been tested despite the widely acknowledged acute chemosensory abilities of copepods. I examined whether three concentrations of the water-soluble fraction of diesel oil (0.01%, 0.1% and 1%) impacts (i) the swimming behavior of both adult males and females of the widespread calanoid copepod Temora longcornis, and (ii) the ability of males to locate, track and mate with females. The three concentrations of the water-soluble fraction of diesel oil (WSF) significantly and non-significantly affect female and male swimming velocities, respectively. In contrast, both the complexity of male and female swimming paths significantly decreased with increasing WSF concentrations, hence suggesting a sex-specific sensitivity to WSF contaminated seawater. In addition, the three WSF concentrations impacted both T. longicornis mating behavior and mating success. Specifically, the ability of males to detect female pheromone trails, to accurately follow trails and to successfully track a female significantly decreased with increasing WSF concentrations. This led to a significant decrease in contact and capture rates from control to WSF contaminated seawater. These results indicate that hydrocarbon contamination of seawater decreases the ability of male copepods to detect and track a female, hence suggest an overall impact on population fitness and dynamics

Effects of the spatial pattern of disturbance on the patch-occupancy dynamics of juniper–pine open woodland

7 poáginas, 4 figuras, 1 tabla.-- El PDF del artículo es el manuscrito del autor.Typically, studies of the disturbance effect on metapopulation dynamics are limited to understanding the effect of habitat loss although, recently, the spatial pattern of the disturbance has been shown to influence dynamics. In this study, we used a stochastic patch-dynamic model to investigate the effects of spatial disturbance patterns on the persistence of an open woodland community of Juniperus spp. and Pinus spp. First, we estimated patch-occupancy dynamics by using the coefficients that best predicted the occupancy observed in 1998 based on occupancy data from 1957. Next, we evaluated the effects of the rate and pattern of the disturbance on the extinction probability. In modeling the disturbance, we considered (1) the degree of disturbance produced by scenarios of complete destruction or degradation (with the potential for recolonization), (2) the overall rate of disturbance, and (3) the spatial autocorrelation of habitat destruction. Twenty 40-year simulations predicted a 25% increase in the number of patches, and when 50% of the habitat was removed, the impact was more pronounced after complete destruction than it was after degradation of the area. Predictions based on scenarios of complete destruction, including random, contiguous, Brownian, and autoregressive noise, demonstrated that the impact of disturbance depends upon the spatial structure of the disturbance regimen. The autocorrelated structure of the disturbance regimen had the greatest impact on patch persistence. Patch-occupancy was higher after 20 40-year simulations when habitat loss was randomly distributed than when it followed an autocorrelated patch destruction, which was simulated using autoregressive noise to produce 50% habitat destruction. In addition, while habitat loss was negatively linearly correlated with patch persistence when habitat destruction was randomly distributed, a dramatic transition shift occurred when habitat destruction was simulated following an autoregressive spatial distribution after a certain threshold of habitat destruction (40% of the actual open woodland habitat). Our study suggests that the spatial patterns of the disturbance should be considered when predicting the consequences of fragmentation and improving management strategies.We gratefully acknowledge the support of the Spanish CICYT (CGL2005-01625/BOS), BIOFRAG.Peer reviewe