Places making: participatory construction of scientifi c culture cities

In the framework of the European project Platform of Local Authorities and Communicators Engaged in Science (PLACES), we analyse the articulations between scientifi c communication, public perception of science, processes of citizen participation and apropiation of space, based on a case study of the inhabitants of Teruel city, Autonomous Community of Aragon, Spain. On the interrelationships between these issues, there are a number of contradictions, such as the difference between a high interest for information about science and technology and a low level of recognition and interaction with local institutions involved in those activities, the complex conceptualization of scientifi c space in relation to the “public-private” pair, or an articulation of a claiming civic rethoric and an insuffi cient co-responsibility. We conclude that, in a local context, the dimension of territoriality and, in particular, the identifi cation with the town, is a central mediation for activating citizen participation as part of processes of appropriation of space for setting up cities of scientifi c culture.

Ca(2+)-sparks constitute elementary building blocks for global Ca(2+)-signals in myocytes of retinal arterioles.

Spontaneous Ca2+-events were imaged in myocytes within intact retinal arterioles (diameter < 40 mu m) freshly isolated from rat eyes. Ca2+-sparks were often observed to spread across the width of these small cells, and could summate to produce prolonged Ca2+-oscillations and contraction. Application of cyclopiazonic acid (20 mu M) transiently increased spark frequency and oscillation amplitude, but inhibited both sparks and oscillations within 60 s. Both ryanodine (100 mu M) and tetracaine (100 mu M) reduced the frequency of sparks and oscillations, while tetracaine also reduced oscillation amplitude. None of these interventions affected spark amplitude. Nifedipine, which blocks store filling independently of any action on L-type Ca2+-channels in these cells, reduced the frequency and amplitude of both sparks and oscillations. Removal of external [Ca2+] (1 mM EGTA) also reduced the frequency of sparks and oscillations but these reductions were slower in onset than those in the presence of tetracaine or cyclopiazonic acid. Cyclopiazonic acid, nifedipine and low external [Ca2+] all reduced SR loading, as indicated by the amplitude of caffeine evoked Ca2+-transients. This study demonstrates for the first time that spontaneous Ca2+-events in small arterioles of the eye result from activation of ryanodine receptors in the SR and suggests that this activation is not tightly coupled to Ca2+-influx. The data also supports a model in which Ca2+-sparks act as building blocks for more prolonged, global Ca2+-signals. (c) 2006 Elsevier Ltd. All rights reserved.

Observations towards early-type stars in the ESO-POP Survey - II. Searches for intermediate- and high-velocity clouds

We present Ca it K and Ti it optical spectra of early-type stars taken mainly from the ultraviolet and visual echelle spectrograph (LIVES) Paranal Observatory Project, plus H 1 21-cm spectra, from the Vila-Elisa and Leiden-Dwingeloo Surveys, which are employed to obtain distances to intermediate- and high-velocity clouds (IHVCs). H I emission at a velocity of -117 km s(-1) towards the sightline HD 30677 (l, b = 190 degrees.2, -22 degrees.2) with column density -1.7 x 10(19) cm(-2) has no corresponding Ca Pi K absorption in the LIVES spectrum, which has a signal-to-noise ratio (S/N) of 610 per resolution element. The star has a spectroscopically determined distance of 2.7 kpc, and hence sets this as a firm lower distance limit towards Anti-Centre cloud ACII. Towards another sightline (HD 46185 with 1, b = 222 0, -10 degrees.1), H1 at a velocity of +122 km s(-1) and column density of 1.2 x 10(19) cm(-2) is seen. The corresponding Ca Pi K spectrum has a S/N of 780, although no absorption is observed at the cloud velocity. This similarly places a firm lower distance limit of 2.9 kpc towards this parcel of gas that may be an intermediate-velocity (IV) cloud. The lack of IV Ca it absorption towards HD 196426 (1, b = 45 degrees.8, -23 degrees.3) at a S/N of 500 reinforces a lower distance limit of -700 pc towards this part of complex gp, where the H I column density is 1.1 x 1019 cm(-2) and velocity is +78 km s(-1). Additionally, no IV Cart is seen in absorption in the spectrum of HD 19445, which is strong in H I with a column density of 8 x 10(19) cm(-2) at a velocity of - -42 km s(-1), placing a firm although uninteresting lower distance limit of 39 pc to this part of IV South. Finally, no high-velocity Call K absorption is seen towards HD 115363 (l, b = 306.0,-1.0) at a S/N of 410, placing a lower distance of -3.2 kpc towards the HVC gas at velocity of - +224 km s(-1) and WE column density of 5.2 x 10(19) cm(-2). This gas is in the same region of the sky as complex WE (Wakker 2001), but at higher velocities. The non-detection of Ca it K absorption sets a lower distance of -3.2 kpc towards the HVC, which is unsurprising if this feature is indeed related to the Magellanic System.

Ca(2+) signals coordinate zygotic polarization and cell cycle progression in the brown alga Fucus serratus

Zygotes of the fucoid brown algae provide excellent models for addressing fundamental questions about zygotic symmetry breaking. Although the acquisition of polarity is tightly coordinated with the timing and orientation of the first asymmetric division-with zygotes having to pass through a G1/S-phase checkpoint before the polarization axis can be fixed -the mechanisms behind the interdependence of polarization and cell cycle progression remain unclear. In this study, we combine in vivo Ca(2+) imaging, single cell monitoring of S-phase progression and multivariate analysis of high-throughput intracellular Ca(2+) buffer loading to demonstrate that Ca(2+) signals coordinate polarization and cell cycle progression in the Fucus serratus zygote. Consistent with earlier studies on this organism, and in contrast to animal models, we observe no fast Ca(2+) wave following fertilization. Rather, we show distinct slow localized Ca(2+) elevations associated with both fertilization and S-phase progression, and we show that both S-phase and zygotic polarization are dependent on pre-S-phase Ca(2+) increases. Surprisingly, this Ca(2+) requirement cannot be explained by co-dependence on a single G1/ S-phase checkpoint, as S phase and zygotic polarization are differentially sensitive to pre-S-phase Ca(2+) elevations and can be uncoupled. Furthermore, subsequent cell cycle progression through M phase is independent of localized actin polymerization and zygotic polarization. This absence of a morphogenesis checkpoint, together with the observed Ca(2+)dependences of S phase and polarization, show that the regulation of zygotic division in the brown algae differs from that in other eukaryotic model systems, such as yeast and Drosophila.