Browsing by Author "Thomas, Daniela"

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    Differential gene expression in Pyropia columbina (Bangiales, Rhodophyta) under natural hydration and desiccation conditions
    (2013) Contreras-Porcia, Loretto; Lopez-Cristoffanini, Camilo; Lovazzano, Carlos; Rosa Flores-Molina, Maria; Thomas, Daniela; Nunez, Alejandra; Fierro, Camila; Guajardo, Eduardo; Correa, Juan A.; Kube, Michael; Reinhardt, Richard
    In rocky shores, desiccation is triggered by daily tide changes, and experimental evidence suggests that local distribution of algal species across the intertidal rocky zone is related to their capacity to tolerate desiccation. In this context, the permanence of Pyropia columbina in the high intertidal rocky zone is explained by its exceptional physiological tolerance to desiccation. This study explored the metabolic pathways involved in tolerance to desiccation in the Chilean P. columbina, by characterizing its transcriptome under contrasting conditions of hydration. We obtained 1,410 ESTs from two subtracted cDNA libraries in naturally hydrated and desiccated fronds. Results indicate that transcriptome from both libraries contain transcripts from diverse metabolic pathways related to tolerance. Among the transcripts differentially expressed, 15% appears involved in protein synthesis, processing and degradation, 14.4% are related to photosynthesis and chloroplast, 13.1% to respiration and mitochondrial function (NADH dehydrogenase and cytochrome c oxidase proteins), 10.6% to cell wall metabolism, and 7.5% are involved in antioxidant activity, chaperone and defense factors (catalase, thioredoxin, heat shock proteins, cytochrome P450). Both libraries highlight the presence of genes/ proteins never described before in algae. This information provides the first molecular work regarding desiccation tolerance in P. columbina, and helps, to some extent, explaining the classical patterns of ecological distribution described for algae across the intertidal zone.
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    LUIGI PROVASOLI AWARD RECIPIENTS
    (2009) Thomas, Daniela; Beltran, Jessica; Flores, Veronica; Contreras, Loretto; Bollmann, Edda; Correa, Juan A.
    As part of a long-term study on the biology and ecology of the intertidal kelp Lessonia nigrescens Bory, we report on the occurrence of gall development on this alga, identified the possible causal agent, and assessed the extent of the phenomenon in two wild stands of the host. Our results showed that galls affecting natural populations of L. nigrescens were associated with the infection by a filamentous brown algal endophyte of the genus Laminariocolax. Assignment to Laminariocolax of the endophytes isolated from cultured gall tissue was based on the (i)high internal transcribed spacer 1 (ITS1) sequence similarity and phylogenetic relationship between the Chilean isolates and several species of the genus Laminariocolax endophytic in other kelps, (ii) reproductive and vegetative features of the endophyte in culture, and (iii) anatomical agreement of fully developed galls of Lessonia with those described for other kelp galls caused by endophytic members of Laminariocolax. Unequivocal identification at the species level of the endophytes infecting Lessonia, however, awaits further studies.
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    Recent Reticulate Evolution in the Ecologically Dominant Lineage of Coccolithophores
    (2016) Bendif, El-Mahdi; Probert, Ian; Díaz Rosas, Francisco Javier; Thomas, Daniela; Van Den Engh, Ger.; Young, Jeremy R.; Dassow, Peter von
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    Seaweeds early development: detrimental effects of desiccation and attenuation by algal extracts
    (2012) Contreras-Porcia, Loretto; Callejas, Sebastian; Thomas, Daniela; Sordet, Camille; Pohnert, Georg; Contreras, Anibal; Lafuente, Ana; Flores-Molina, Maria R.; Correa, Juan A.
    The effects of desiccation on the early development stages of Mazzaella laminarioides, Scytosiphon lomentaria and Lessonia nigrescens, algal species with different patterns of distribution across the intertidal zone, were examined in the laboratory. In addition, the protective effect against desiccation was evaluated using algal extracts, including those from Porphyra columbina, a macroalga tolerant to desiccation that lives in the uppermost part of the intertidal zone. Our results showed that M. laminarioides displayed the highest resistance to daily desiccation, followed by S. lomentaria, whereas L. nigrescens was the most susceptible. Spores from L. nigrescens exposed to desiccation, although being able to germinate, ceased further post-germination development. In addition, our results showed that all species exposed to extracts from desiccated P. columbina successfully completed their development and strongly suggest the occurrence of compounds with protective properties that help in attenuating the stress caused by desiccation. Finally, our results indicate that the magnitude of the effects generated by desiccation on the early algal development is related to the position of the species in the intertidal zone, and that the protective effects of P. columbina extracts reveal an exceptional metabolism of this species under desiccation stress.