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- Polymorphism of Saccharomyces cerevisiae aquaporinsPublication . Laizé, Vincent; Tacnet, F.; Ripoche, P.; Hohmann, S.Aquaporin water channels facilitate the transmembrane diffusion of water and higher organisms possess a large number of isoforms. The genome of the yeast Saccharomyce cerevisiae contains two highly similar aquaporin genes, AQY1 and AQY2. AQY1 has been shown to encode a functional water channel but only in certain laboratory strains. Here we show that the AQY2 gene is interrupted by an 11 bp deletion in 23 of the 27 laboratory strains tested, with the exception of strains from the S1278b background, which also exhibit a functional Aqy1p. However, although the AQY2 gene from S1278b is highly homologous to functional aquaporins, we did not observe Aqy2p mediated water transport in Xenopus oocytes. A survey of 52 yeast strains revealed that all industrial and wild yeasts carry the allele encoding a functional Aqy1p, while none of these strains appear to have a functional Aqy2p. We conclude that natural and industrial conditions provide selective pressure to maintain AQY1 but apparently not AQY2.
- Single hydrophone source localizationPublication . Jesus, S. M.; Porter, M. B.; Stephan, Y.; Demoulin, X.; Rodríguez, O. C.; Coelho, E.The method presented in this paper assumes that the received signal is a linear combination of delayed and attenuated uncorrelated replicas of the source emitted waveform. The set of delays and attenuations, together with the channel environmental conditions, provide sufficient information for determining the source location. If the transmission channel is assumed known, the source location can be estimated by matching the data with the acoustic field predicted by the model conditioned on the estimated delay set. This paper presents alternative techniques that do not directly attempt to estimate time delays from the data but, instead, estimate the subspace spanned by the delayed source signal paths. Source localization is then done using a family of measures of the distance between that subspace and the subspace spanned by the replicas provided by the model. Results obtained on the INTIMATE’96 data set, in a shallow-water acoustic channel off the coast of Portugal, show that a sound source emitting a 300–800-Hz LFM sweep could effectively be localized in range or depth over an entire day.