Browsing by Author "Cardenas, Leyla"

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    Differential expression of stress candidate genes for thermal tolerance in the sea urchin Loxechinus albus
    (2017) Vergara-Amado, Jonathan; Silva, Andrea X.; Manzi, Catalina; Nespolo, Roberto F.; Cardenas, Leyla
    Marine ectotherms inhabiting intertidal and shallow subtidal environments are continuously exposed to diurnal tidal cycles and seasonal variability in temperature. These organisms have adaptive mechanisms to maintain cellular homeostasis, irrespective of thermal environmental variation. In this study, we describe the molecular responses to thermal stress in the edible sea urchin Loxechinus albus. In particular, we determined the differential expression of a set of molecular markers that have been identified as targets of stress-related responses. These include the heat shock proteins (hsp70 and hsp90), cell detoxification proteins (cytochrome P450), and osmorregulatory proteins (a and beta-Na+/K+ ATPase). We exposed individuals to different temperatures; a warm treatment (18 +/- 1.0 degrees C), a cold treatment (10 1.0 degrees C), and a control treatment (average local temperature of 14 +/- 1.0 degrees C) and differential expression was quantified after 2, 6, 12 and 48 h of exposure. Levels of mRNA were quantified by reverse transcription-quantitative polymerase chain reaction, and the relative expression of each gene was calculated using the 18S rRNA gene as a reference, and the control treatment as a calibrator. We found that the expression levels of all studied genes increased during exposure to warmth. The largest increase in expression was observed in cytochrome p450 genes (ca. sixteen-fold); this was followed by increases in the expression of the Na+/K+ ATPase (ca. eight-fold) and by the lisp (ca. six fold) genes. These results indicate that sea urchin thermal stress responses depend on differential gene-regulation, involving heat-shock, membrane potential, and detoxification genes that generate an integrated adaptive response to acute environmental changes.
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    Genetic population structure in the Chilean jack mackerel, Trachurus murphyi (Nichols) across the South-eastern Pacific Ocean
    (2009) Cardenas, Leyla; Silva, Andrea X.; Magoulas, Antonios; Cabezas, Josefina; Poulin, Elie; Patricio Ojeda, F.
    The Chilean jack mackerel Trachurus murphyi, is a pelagic fish from the Carangidae family that is distributed in the South Pacific Ocean. Because this species constitutes an important economic resource across the South Pacific and plays an important ecological role in this ecosystem there is a growing interest in determining its population structure. In this study, we used molecular markets (mitochondrial DNA sequences and microsatellites) from Chilean jack mackerel samples to investigate its genetic population structure across the South Pacific Ocean. The mitochondrial DNA did not detect a genetic structure in T murphyi populations in the Pacific Ocean, but revealed very low haplotype diversity and a short genealogy history compared to other small-pelagic species. The same general pattern of a lack of genetic structure was found with microsatellite loci; however, a large genetic diversity was revealed with microsatellite markers. The present results did not support the existence of different stock units for T murphyi across the South Pacific Ocean but a more holistic approach will be necessary to determine an adequate management strategy for this fishery. (C) 2009 Elsevier B.V. All rights reserved.
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    Isolation and characterization of 11 polymorphic microsatellite markers for the marine gastropod Concholepas concholepas (Brugiere, 1789)
    (2007) Cardenas, Leyla; Daguin, Claire; Castilla, Juan Carlos; Viard, Frederique
    Because of its long-lived planktonic stage, the marine gastropod Concholepas concholepas is expected to exchange larvae over large distances. However, discrepancies between expected and realized dispersal have been documented in marine invertebrates. To investigate relationships between potential and effective (i.e. gene flow) dispersal, we developed 11 microsatellite markers and investigate their usefulness by analysing two populations distant by c. 4000 km. The 11 loci were found to be highly polymorphic in both populations, with 12-51 alleles according to the locus. This polymorphism is strong enough to allow fine-scale population analyses including larval studies and paternity analyses.