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Leroy F.,University Pierre and Marie Curie | Leroy F.,French National Center for Scientific Research | Comtet T.,University Pierre and Marie Curie | Brante A.,Catholic University of the Holy Conception | And 4 more authors.
Journal of Molluscan Studies | Year: 2012

Many marine gastropod species brood their embryos in thin-walled capsules to protect them during development. Despite its beneficial effects, encapsulation has two major constraints, nutrition and oxygen supply, which affect embryo development and larval survival. Developing embryos usually rely on intracapsular food sources provided by the mother, in the form of yolk, nurse eggs and intracapsular fluid. However, it is still not clear if they are able to feed on extracapsular sources that may cross the capsule wall. We investigated this possibility in the calyptraeid species Crepidula fornicata. In this species, the internal capsule wall thickness sharply decreases during embryonic development, which might change wall permeability to small organic molecules, thus providing embryos with external dissolved organic matter. To test this hypothesis, encapsulated and excapsulated embryos of C. fornicata were placed for 48 h in a 13C-enriched amino acid (l-alanine) solution. Excapsulated embryos were enriched in 13C (5.75‰), which suggested that they were able to assimilate the labelled amino acid. In contrast, encapsulated embryos were weakly enriched (0.75‰), suggesting that encapsulation greatly reduces the potential for the use of extracapsular amino acids and that encapsulated embryos mainly rely on maternal food. © 2011 The Author. Source

Sartor C.E.,CONICET | Marone L.,CONICET | Marone L.,Center for Advanced Studies in Ecology and Biodiversity | Marone L.,National University of Cuyo
Journal of Arid Environments | Year: 2010

Annual forbs form short-term persistent soil seed banks whereas perennial grasses form mostly transient ones in the central Monte desert. A conceptual framework predicts that annual forb seeds will have primary dormancy, whereas perennial grasses will have low dormancy levels. We assessed whether the dormancy traits of four annual forb species and five perennial grass species can account for their soil seed bank dynamics. To overcome dormancy, we treated perennial grasses and autumn annual forbs with high temperatures, and spring annual forbs with low temperatures. To force seeds into secondary dormancy we exposed non-dormant perennial grasses to low temperatures. Most of the annual forbs and two perennial grasses (Setaria leucopila and Sporobolus cryptandrus) showed low germination rates. The remaining perennial grasses presented moderate (Pappophorum caespitosum and Digitaria californica) or high germination levels (Trichloris crinita). Low temperatures increased germination in spring forbs (Chenopodium papulosum and Parthenium hysterophorus), but high temperatures did not break dormancy in autumn forbs (Sphaeralcea miniata and Phacelia artemisioides). Germination of perennial grasses increased after they had been exposed to high temperatures, but only two species reentered into dormancy under low temperature. Given that in the central Monte desert winter-autumn granivores eat mainly grass seeds, we conclude that high seed dormancy and low consumption may contribute to the persistent soil seed bank of most forbs, and that seed dormancy itself does not explain the transience of grass seed banks. © 2009 Elsevier Ltd. All rights reserved. Source

Castro S.A.,University of Santiago de Chile | Castro S.A.,Center for Advanced Studies in Ecology and Biodiversity | Badano E.,University of Concepcion | Guzman D.,University of Santiago de Chile | Cavieres L.,University of Concepcion
Biological Invasions | Year: 2010

In central Chile, the bur beak chervil (Anthriscus caucalis M. Bieb.; Apiaceae) is an annual naturalized herb introduced from Europe at least 120 years ago. Anthriscus is distributed in vegetation formations such as sclerophyllous shrublands (locally known as "matorral") and spiny savannas of Acacia caven (locally known as "espinal"). In matorral formations, Anthriscus grows at the edge of native woody fragments. Because these fragments are refuges where native herbs recruit, we studied the impact of Anthriscus on the diversity and survival of native forbs established in these sheltering microsites. First, we characterized the spatial distribution of Anthriscus in the matorral, sampling in different micro-habitat types. We differentiated three microhabitat types: under the canopy of a fragment, at the edge of the canopy of a fragment, and in open sites outside the fragments. A total of 40 1 × 1 m quadrates were randomly distributed in each habitat type. Inside each of them, we recorded the number of seedlings and established plants, including Anthriscus. Then we evaluated experimentally the effect of Anthriscus on diversity and evenness of the local herb assemblages. For this purpose we conducted a field trial using 34 metallic enclosures (0.5 × 0.5 m) arranged in pairs. In each pair, Anthriscus individuals were removed from one plot, the other paired plot acting as control. We periodically recorded the presence and abundance of the remanent species of herbs inside the plots, and then we characterized the species diversity and evenness over time (Shannon's index, H′ and Pielou's index, J′). Finally, in a second experiment we measured experimentally the presence or absence of Anthriscus against the survival of four native herb species (Bowlesia incana, Bromus berteroanus, Pectocarya linearis, and Moscharia pinnatifida). Here we used 20 0.5 × 0.5 m plots where we randomly transplanted seedlings of native herbs and Arnthiscus. Then, for each species and plot we determined their survival (%) according to the number of seedlings initially transplanted. The samplings show strong association between the presence of Anthriscus on edge habitat in the matorral. The maximum densities were noted in these microhabitat types whereas in open areas and under-fragment sites Anthriscus shows very low or null densities. At the end of the first trials, the plots with Anthriscus showed a Shannon diversity index H′ = 0. 41 (±0. 11 SE), while in plots without Anthriscus this value was 1. 19 (±0. 1 SE), both as averages. Pielou's evenness index (J′) yielded values of 0. 23 (±0.06 SE) and 0.59 (±0.04 SE) for treatments with and without Anthriscus, respectively. Similarly, the second trials shows that the survival of the four native herbs was drastically decreased in the presence of Anthriscus: by 64% for Bowlesiaincana, 43% for Bromusberteroanus, 46% for Moscharia pinnatifida, and 76% for Pectocarialinearis. Our study shows that the effects of Anthriscus include an inhibition of the establishment of native plants and a decrease in their survival in edge habitats, therefore affecting the composition and diversity of the local herb layer. Thus, Anthriscus is invading a refuge habitat for native herbs in the Chilean matorral, decreasing the native herb diversity and survival. © Springer Science+Business Media B.V. 2009. Source

Figueroa D.P.,University of Chile | Sabat P.,University of Chile | Sabat P.,Center for Advanced Studies in Ecology and Biodiversity | Torres-Contreras H.,University of Chile | And 2 more authors.
Journal of Insect Physiology | Year: 2010

Small animals need efficient water conservation mechanisms for survival and reproduction, which is relevant for the spiders that have large book lungs with large respiratory surface. If lung evaporation is relevant to limit water loss, adjustments of the spiracle opening to metabolic demands should be expected. In this study, we measured the metabolic rate and total evaporative water loss mediated by the opening of the spiracles in the migalomorph spider Paraphysa parvula, a resident of fluctuating Mediterranean environments of the mountains of central Chile. We found that the metabolism of P. parvula was similar to other Theraphosidae and low compared to other arthropods. Carbon dioxide production and evaporative water loss increased with temperature, particularly at 40°C. The total evaporative water loss at 40°C increased dramatically to about 10 times that found with the lower temperatures. Thus, 40°C will be the limit temperature for this species after which evaporative water loss starts to become damaging, so it has to avoid it. The exposition to hypercapnic environments had as a consequence an increase in evaporative water loss and the involvement of the book lungs in this loss was about 60%. The possibility of losing water could condition this species to seek temperate and oxygenated shelters under rocks. © 2010 Elsevier Ltd. Source

Contreras L.,Center for Advanced Studies in Ecology and Biodiversity | Moenne A.,University of Santiago de Chile | Gaillard F.,French National Center for Scientific Research | Potin P.,University Pierre and Marie Curie | Correa J.A.,Center for Advanced Studies in Ecology and Biodiversity
Aquatic Toxicology | Year: 2010

A proteomic analysis combining peptide de novo sequencing and BLAST analysis was used to identify novel proteins involved in copper tolerance in the marine alga Scytosiphon gracilis (Phaeophyceae). Algal material was cultivated in seawater without copper (control) or supplemented with 100 μg L-1 for 4 days, and protein extracts were separated by two-dimensional gel electrophoresis (2-DE). From the proteins obtained in the copper treatment, 25 over-expressed, 5 under-expressed and 5 proteins with no changes as compared with the control, were selected for sequencing. Tryptic-peptides obtained from 35 spots were analyzed by capillary liquid chromatography and tandem mass spectroscopy (capLC/MS/MS), and protein identity was determined by BLASTP. We identified 19 over-expressed proteins, including a chloroplast peroxiredoxin, a cytosolic phosphomannomutase, a cytosolic glyceraldehyde-3-phosphate dehydrogenase, 3 ABC transporters, a chaperonine, a subunit of the proteasome and a tRNA synthase, among others. The possible involvement of these over-expressed proteins in buffering oxidative stress and avoiding metal uptake in S. gracilis exposed to copper excess is discussed taking into consideration the information available for other plant models. © 2009 Elsevier B.V. All rights reserved. Source

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