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  • Suppression subtractive hybridization for studying gene expression during aerial exposure and desiccation in fucoid algae
    Publication . Pearson, G. A.; Serrão, Ester; Cancela, Leonor
    Gene expression in Fucus vesiculosus L. from the Ria Formosa, Faro, Portugal was investigated by screening a cDNA library generated by suppression subtractive hybridization (SSH) for algae undergoing mild desiccation stress (60–70%tissue water content). The subtractive library was constructed from small amounts (1 µg) of total RNA using PCR-based techniques. Screening by reverse Northern analysis (cDNA Southerns) revealed that between 60% and 70% of clones randomly selected from the library were differentially regulated in desiccated and hydrated algae. Most genes could not be directly identified based on sequence homology with known gene sequences. However, several cDNAs for chloroplast encoded transcripts were identified and shown to be up-regulated or differentially regulated in desiccated algae relative to hydrated controls. These included partial sequences for ribulose-l,5-bisphosphate carboxylase/oxygenase (Rubisco; rbcL/rbcS), chloroplast coupling factor ATPase (atpH/atpI) and a photosystem I P700 chlorophyll a binding protein (psaA). The usefulness of reverse Northern analysis was confirmed with conventional Northern analysis of transcript abundance for Rubisco, which varied rapidly in response to light and the hydration status of the algae. These results show that SSH is a useful technique for analysing the responses of gene expression to environmental stress, and as a starting point for the subsequent identification of stress-responsive genes in macroalgae.
    2001-11Journal article Restricted access Show more
  • The dependence of the anomalous J/psi suppression on the number of participant nucleons
    Publication . M. C. Abreu; Alessandro, B.; Alexa, C.; Arnaldi, R.; Atayan, M.; Baglin, C.; Baldit, A.; Bedjidian, M.; Beole, S.; Boldea, V.; Bordalo, P.; Borges, G.; Bussiere, A.; Capelli, L.; Castor, J.; Castanier, C.; Chaurand, B.; Chevrot, I; Cheynis, B; Chiavassa, E; Cicalo, C; Claudino, T; Comets, M. P.; Constans, N.; Constantinescu, S.; Cortese, P.; De Marco, N.; De Falco, A.; Dellacasa, G.; Devaux, A.; Dita, S.; Drapier, O.; Ducroux, L.; Espagnon, B.; Fargeix, J.; Force, P.; Grigorian, A. A.; Grigorian, S.; Grossiord, J. Y.; Guber, F. F.; Guichard, A.; Gulkanyan, H.; Hakobyan, R.; Haroutunian, R.; Idzik, M.; Jouan, D.; Karavitcheva, T. L.; Kluberg, L.; Kurepin, A. B.; Le Bornec, Y.; Lourenco, C.; Macciotta, P.; Mac Cormick, M.; Marzari-Chiesa, A.; Masera, M.; Masoni, A.; Monteno, M.; Musso, A.; Petiau, P.; Piccotti, A.; Pizzi, J. R.; Prino, F.; Puddu, G.; Quintans, C.; Ramos, S.; Ramello, L.; Mendes, P. R.; Riccati, L.; Romana, A.; Santos, H.; Saturnini, P.; Scalas, E.; Scomparin, E.; Serci, S.; Shahoyan, R.; Sigaudo, F.; Silva, S.; Sitta, M.; Sonderegger, P.; Tarrago, X.; Topilskaya, N. S.; Usai, G. L.; Vercellin, E.; Villatte, L.; Willis, N.
    The observation of an anomalous J/psi suppression in Pb-Pb collisions by the NA50 Collaboration can be considered as the most striking indication for the deconfinement of quarks and gluons at SPS energies. In this Letter, we determine the J/psi suppression pattern as a function of the forward hadronic energy E-ZDC measured in a Zero Degree Calorimeter (ZDC). The direct connection between EZDC and the geometry of the collision allows us to calculate, within a Glauber approach, the precise relation between the number of participant nucleons N-part and E-ZDC. Then, we check if the experimental data can be better explained by a sudden or a smooth onset of the anomalous J/psi suppression as a function of the number of participants. (C) 2001 Elsevier Science B.V. All rights reserved.
    2001-11Journal article Open access Show more