In Saccharomyces cerevisiae, the diffusion rate of hydrogen peroxide (H2O2) through the plasma membrane decreases during adaptation to H2O2 by means of a mechanism that is still unknown. Here, evidence is presented that during adaptation to H2O2 the anisotropy of the plasma membrane increases. Adaptation to H2O2 was studied at several times (15min up to 90min) by applying the steady-state H2O2 delivery model. For wild-type cells, the steady-state fluorescence anisotropy increased after 30min, or 60min, when using 2-(9-anthroyloxy) stearic acid (2-AS), or diphenylhexatriene (DPH) membrane probe, respectively. Moreover, a 40% decrease in plasma membrane permeability to H2O2 was observed at 15min with a concomitant two-fold increase in catalase activity. Disruption of the ergosterol pathway, by knocking out either ERG3 or ERG6, prevents the changes in anisotropy during H2O2 adaptation. H2O2 diffusion through the plasma membrane in S. cerevisiae cells is not mediated by aquaporins since the H2O2 permeability constant is not altered in the presence of the aquaporin inhibitor mercuric chloride. Altogether, these results indicate that the regulation of the plasma membrane permeability towards H2O2 is mediated by modulation of the biophysical properties of the plasma membrane.

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Eurasian otter, Lutra lutra (L., 1758), spraints collected at the Aguieira hydroelectric dam (central Portugal, n = 916) and tributaries (n = 412) were analysed to assess diet compared with prey availability. Fish and crayfish abundances in the reservoir were assessed with fyke and trammel nets. Prey availability in the tributaries was estimated by electrofishing. In both the reservoir and its tributaries, fish were the main prey and consisted predominantly of Lepomis gibbosus (L., 1758) (60%–65% of occurrences), which is an introduced species of Centrachidae that is abundant in the reservoir but is almost absent in the tributaries. These data suggest that otters using the tributaries feed predominantly in the reservoir. Seasonal dietary variations corresponded to increased availability of nonfish prey categories. Capture vs. consumption analyses demonstrated that otters did not consume L. gibbosus according to its availability. In fact, L. gibbosus was consumed less frequently when other prey species were more available (e.g., amphibians, eels, barbells). The tributaries offer important otter refuge areas that are scarce at the edge of the reservoir, and so, in large reservoirs care should be taken to minimize disturbance in the surrounding catchments. Results indicate that otter populations make use of these conjoint systems to ensure their survival.

The number of dams is progressively increasing, but nonetheless there are few examples of long‐term studies involving otters and these structures. This study assessed how Eurasian otter Lutra lutra responded over time to environmental changes imposed by the construction of a large reservoir, the Alqueva Dam (250 km2, SE Portugal). Otter distribution was monitored over four phases (pre‐deforestation/flooding, deforestation, flooding, and post‐flooding) from 2000 to 2006 in both the flooded and surrounding areas. During each phase, presence was assessed at two resolutions: 25 km2 (76 survey sites in wet and dry seasons) and 1 km2 (39 survey sites, every three months). In addition, otter spraints were collected at eight survey sites in 2000 (pre‐dam) and 2006 (post‐dam) to assess and compare otter diet with prey availability. Otters were widespread before dam construction (>82.4% positive cells), decreased during deforestation (68.5%), and particularly during the flooding phase (33.3%), recovered during the post‐flooding phase, although not at the level recorded before dam construction (61.5–83.3%). Otter diet was dominated by fish and American crayfish Procambarus clarkii during the pre‐deforestation/flooding phase (56.7% fish, 35.3% crayfish) and at the end of the post‐flooding phase (60.7% fish, 33.2% crayfish). Species richness of fish prey decreased with flooding (16 to 8), as did the ratio of native/non‐native fish species (1.7 to 0.3). Changes in the availability of the main ecological requirements of otter were similar to the changes in the observed otter distribution in the flooded area throughout the impact phases, and decreased during deforestation and flooding with some recovery in the post‐flooding phase. The results emphasize the importance of long‐term monitoring studies that include several post‐impact phases, to evaluate species response to impacts. This will allow better planning of mitigation and compensation measures. Copyright © 2013 John Wiley & Sons, Ltd.

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Large dam construction in water deficient areas is a management decision often controversial. Besides providing water storage, economical benefits, and a source of renewable energy, the construction and flooding caused by large dams cause disruptions in natural systems. We monitored the pre- and post-Alqueva dam impacts on the threatened carnivore species (polecat, otter, wildcat and Iberian lynx) populations in SE Portugal, and assessed which factors mostly contribute to post-dam distribution. Major short term impacts of large dams are: (1) increase in accessibility and human presence; (2) movement of heavy machinery and dam-workers; (3) deforestation with habitat loss and fragmentation; (4) change from lotic to lentic system; (5) lower prey availability and harsher capture; and (6) changes in land use adjacent to the reservoir. Thus, the response to those impacts can be predicted as a decline of polecat, wildcat and lynx distribution ranges, and a recovery of the otter from the severe short term impacts. Our results corroborate this hypothesis for all the species, especially during deforestation/early flooding. Otter's distribution range increased in the phase of greater impact, with a subsequent decrease with flooding. Our results suggest carnivores used "escape" areas with favourable habitat and prey conditions, however, the areas with higher probability of species presence decreased by two fold showing a drastic range reduction. To ensure populations' survival of these charismatic threatened carnivore populations of Mediterranean landscapes of south-east Portugal, we propose continuing the monitoring program and the development of a conservation program for the subsisting areas of optimal and suboptimal habitats.

Eurasian otters (Lutra lutra Linnaeus, 1758) are present in a wide range of aquatic environments. Salmonella isolates have been obtained from otters at rehabilitation centers and in the wild and are sometimes associated with serious illnesses. Antimicrobial-resistant Salmonella were isolated from otter fecal samples collected in March 2006, September 2007, and March 2008 in two river basins in southern Portugal. From 67 samples tested, five were positive for Salmonella (7.58%). None of the isolates were susceptible to all antimicrobials tested, and all were resistant to multiple antimicrobials. Our results confirm the role of otters as potential carriers of Salmonella and the importance of environmental exposure to antimicrobial agents in selection for resistance in bacteria.