Browsing by Issue Date, starting with "2001-12"
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- Existence of a tightly regulated water channel in saccharomyces cerevisiaePublication . Meyrial, V.; Laizé, Vincent; Gobin, R.; Ripoche, P.; Hohmann, S.; Tacnet, F.The Saccharomyces cerevisiae strain Σ1278b possesses two putative aquaporins, Aqy1-1p and Aqy2-1p. Previous work demonstrated that Aqy1-1p functions as a water channel in Xenopus oocyte. However, no function could be attributed to Aqy2-1p in this system. Specific antibodies were used to follow the expression of Aqy1-1p and Aqy2-1p in the yeast. Aqy1-1p was never detected whatever the growth phase and culture conditions tested. In contrast, Aqy2-1p was detected only during the exponential growth phase in rich medium containing glucose. Aqy2-1p expression was repressed by hyper-osmotic culture conditions. Both immunocytochemistry and biochemical subcellular fractionation demonstrated that Aqy2-1p is located on the endoplasmic reticulum (ER) as well as on the plasma membrane. In microsomal vesicles enriched in ER, a water channel activity due to Aqy2-1p was detected by stopped-flow analysis. Our results show that the expression of aquaporins is tightly controlled. The physiological relevance of aquaporin-mediated water transport in yeast is discussed.
- Formal schooling influences two- but not three-dimensional naming skillsPublication . Reis, Alexandra; Magnus Petersson, Karl; Castro-Caldas, A.; Ingvar, MartinThe modulatory influence of literacy on the cognitive system of the human brain has been indicated in behavioral, neuroanatomic, and functional neuroimaging studies. In this study we explored the functional consequences of formal education and the acquisition of an alphabetic written language on two- and three-dimensional visual naming. The results show that illiterate subjects perform significantly worse on immediate naming of two-dimensional representations of common everyday objects compared to literate subjects, both in terms of accuracy and reaction times. In contrast, there was no significant difference when the subjects named the corresponding real objects. The results suggest that formal education and learning to read and to write modulate the cognitive process involved in processing two- but not three-dimensional representations of common everyday objects. Both the results of the reaction time and the error pattern analyses can be interpreted as indicating that the major influence of literacy affects the visual system or the interaction between the visual and the language systems. We suggest that the visual system in a wide sense and/or the interface between the visual and the language system are differently formatted in literate and illiterate subjects. In other words, we hypothesize that the pattern of interactions in the functional-anatomical networks subserving visual naming, that is, the interactions within and between the visual and language processing networks, differ in literate and illiterate subjects. (C) 2001 Elsevier Science.
- Racismo, etnicidade e nacionalismo. Que articulação?Publication . Marques, João FilipeGrande parte das reflexões sociológicas e políticas acerca das sociedades acerca das sociedades contemporâneas utiliza as categorias raciais, étnicas e nacionais de uma forma essencialista ou reificadora.
- The use of Artemia sp. or mysids as food source for hatchlings of the cuttlefish (Sepia officinalis L.); effects on growth and survival throughout the life cyclePublication . Domingues, Pedro M.; Sykes, António V.; Andrade, José PedroTwo experiments were conducted to determine the effects of Artemia sp. or mysids on growth and survival of S. offıcinalis hatchlings, and their effect throughout the life cycle. For experiment I, for the first 20 days, one group was fed adult Artemia sp. and the other was fed mysid shrimp (Paramysis nouvelli). Eggs laid by females in both groups were counted and weighed, and hatchlings were weighed, to determine differences in both groups. For experiment II, during the first 10 days, one group was fed Artemia sp. and the other was fed mysids (P. nouveli). After the period of differentiated feeding, the 2 groups in experiment I were fed grass shrimp (Paleomonetes varians) to 70 days old, and dead crabs (Carcinus maenas) afterwards. Cuttlefish in experiment II were fed grass shrimp from day 10 until the end of the experiment. For both experiments, hatchlings fed mysids grew significantly bigger (p < 0.01) and survival was higher. For experiment I, eggs laid by females fed mysids and the hatchlings born from these eggs were bigger (p < 0.001) compared to the group fed Artemia sp. initially. Individual fecundity was slightly higher for females in the group fed Artemia sp. (163 eggs female−1) than for the group fed mysids (144 eggs female−1). Egg laying started at the age of 125 days and lasted 45 days in both groups. Time between first egg laying day and first hatchlings to be born was 21 days. The last female to die (after spawning) in both groups was 167 days (less than 6 months old).
- Gut evacuation rates in Nephrops norvegicus (L., 1758): laboratory and field estimatesPublication . Cristo, MargaridaEstimates of gut evacuation rates of Nephrops norvegicus (Linnaeus, 1758) (Crustacea, Decapoda) were obtained during laboratory and field experiments. Individuals were collected off the south coast of Portugal in December 1997 and July 1998. Gut evacuation rates (R.h(-1)) were calculated from the slope of the regression of the natural logarithm of dry stomach content weight versus time, using data obtained by the "serial slaughter method". The values obtained during laboratory (R = 0.172 h(-1)) and field experiments (R = 0.177 h(-1)) are compared with gut evacuation rates reported for other marine organisms. The results obtained for both experiments are within the range of the values in the literature, even in the case in which different methodologies were used.