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Effect of lysine acetylsalicylate on aluminium accumulation and (Na+/K+)ATPase activity in rat brain cortex synaptosomes after aluminium ingestion
No full textAluminium is neurotoxic in humans and has been implicated in several neurological disorders. Chronic
use of buffered aspirins, as aspegic, would likely constitute the major human aluminium uptake source.
Low-dose aspirin is beneficial in secondary prevention of cardiovascular events, so it is widely used for
long periods of time. We studied if oral administration of aspegic to rats modified the aluminium
inhibitory effect on brain (Na+/K+)ATPase due to alteration in synaptosomal membrane aluminium
content. Adult male Wistar rats were submitted to sub-acute (1.00 g/day during 10 days) and chronic
(0.03 g/day during 4 months) dietary AlCl3 exposure and/or to aspegic (0.11 g/day). The exposure protocol
increased the synaptosomal aluminium content especially after a long-term exposure to aluminium and
aspegic. Although no alterations were observed in rat body weight gain and adenylate energy charge, the
(Na+/K+)ATPase activity was significantly reduced when aluminium was orally administered to rats. The
oral administration of aspegic increased the synaptosomal aluminium content and concomitantly
enhanced the (Na+/K+)ATPase inhibition. In our exposure protocol the increase in synaptosomal
aluminium content correlates with the reduction of the (Na+/K+)ATPase activity
How to mitigate impacts of wind farms on bats? A review of potential conservation measures in the European context
No full textWind energy is growingworldwide as a source of power generation. Bat assemblagesmay be negatively affected
by wind farms due to the fatality of a significant number of individuals after collidingwith the moving turbines or
experiencing barotrauma. The implementation of wind farms should followstandard procedures to prevent such
negative impacts: avoid, reduce and offset, in what is known as the mitigation hierarchy. According to this
approach avoiding impacts is the priority, followed by the minimisation of the identified impacts, and finally,
when residual negative impacts still remain, those must be offset or at least compensated. This paper presents
a review on conservation measures for bats and presents some guidelines within the compensation scenario,
focusing on negative impacts that remain after avoidance and minimisation measures. The conservation
strategies presented aim at the improvement of the ecological conditions for the bat assemblage as a whole.
While developed under the European context, the proposed measures are potentially applicable elsewhere,
taking into consideration the specificity of each region in terms of bat assemblages present, landscape features
and policy context regarding nature and biodiversity conservation and management. An analysis of potential
opportunities and constraints arising from the implementation of offset/compensation programmes and gaps
in the current knowledge is also considered
Toxicity assessment of aqueous extracts of ash from forest fires
No full textWildfires can cause immediate and drastic impacts on the structure and functioning of ecosystems, and there has
been an increasing interest in wildfire effects on water chemistry and aquatic biota. Wildfires are increasingly
recognized as a diffuse source of contamination of aquatic ecosystems, through the production of deleterious pyrolytic
substances and their subsequent transport,mostly attached to ashes. To study the deleterious effects of the
ash-laden runoff fromburnt areas on water quality, composite ash samples of ashes were collected immediately
after a forest fire and then used to prepare aqueous extracts of ash (AEA). The AEAwere analyzedwith respect to
a large group of chemical elements and the sixteen prioritized polycyclic aromatic hydrocarbons (PAHs). Ca, S,
Mg, K and Na were found to be the principal elements in the AEA, while only two low molecular weight PAHs
(phenanthrene and naphthalene) were present in quantifiable amounts. In parallel, an ecotoxicological screening
of the AEA was performed with four standard aquatic species from different functional groups and trophic levels.
The AEA was found to induce a statistically significant decrease in the growth of two primary producers –
Pseudokirchneriella subcapitata and Lemna minor – and inhibited the luminescence of the bacteria Vibrio fischeri.
By contrast, AEA did not produce a significant immobilization of Daphniamagna suggesting that short-termacute
toxicity may be absent at higher trophic levels. Overall, the present results emphasize the role of wildfires as a
potential source of diffuse contamination for downstream water bodies, compromising both chemical and
ecological conditions. At the same time, this study highlights the need for further research into the complexity
of the potentially deleterious ecological effects of wildfires on aquatic communities, with a particular focus on
cascading effects along the trophic web
Developing a co-culture system for effective megakaryo/thrombopoiesis from umbilical cord blood hematopoietic stem/progenitor cells
No full textBackground aims. Platelet transfusion can be a life-saving procedure in different medical settings. Thus, there is an increasing
demand for platelets, of which shelf-life is only 5 days. The efficient ex vivo biomanufacturing of platelets would allow
overcoming the shortages of donated platelets. Methods. We exploited a two-stage culture protocol aiming to study the effect
of different parameters on the megakaryo/thrombopoiesis ex vivo. In the expansion stage, human umbilical cord blood
(UCB)-derived CD34þ-enriched cells were expanded in co-culture with human bone marrow mesenchymal stromal cells
(BM-MSCs). The megakaryocytic commitment and platelet generation were studied, considering the impact of exogenous
addition of thrombopoietin (TPO) in the expansion stage and a cytokine cocktail (Cyt) including TPO and interleukin-3 in
the differentiation stage, with the use of different culture medium formulations, and in the presence/absence of BM-MSCs
(direct versus non-direct cell-cell contact). Results. Our results suggest that an early megakaryocytic commitment, driven by
TPO addition during the expansion stage, further enhanced megakaryopoiesis. Importantly, the results suggest that coculture
with BM-MSCs under serum-free conditions combined with Cyt addition, in the differentiation stage, significantly
improved the efficiency yield of megakaryo/thrombopoiesis as well as increasing %CD41, %CD42b and polyploid
content; in particular, direct contact of expanded cells with BM-MSCs, in the differentiation stage, enhanced the efficiency
yield of megakaryo/thrombopoiesis, despite inhibiting their maturation. Conclusions. The present study established an in vitro
model for the hematopoietic niche that combines different biological factors, namely, the presence of stromal/accessory cells
and biochemical cues, which mimics the BM niche and enhances an efficient megakaryo/thrombopoiesis process ex vivo
Assessment of antibiotic resistance of Escherichia coli isolates and screening of Salmonella spp. in wild ungulates from Portugal
No full textAntibiotic resistance is an emerging global problem. Wild animals are rarely exposed to antibiotics and therefore low levels of antibiotic
resistance are expected. However, the growing interactions of these animals with humans and livestock may have a huge impact on their bacterial
flora. This study aimed to assess the levels of antibiotic resistance in Escherichia coli isolated from widespread wild ungulates in Portugal. The
interpretation of inhibition zone diameters was performed according to clinical breakpoints and epidemiological cut-offs, determined with the
normalized resistance interpretation (NRI) method. For clinical breakpoints, 16% of the isolates were resistant to at least one antibiotic,
including ampicillin (10%), tetracycline (9%), streptomycin (5%) co-trimoxazole (4%), amoxicillin/clavulanic acid (1%) and cefoxitin (1%).
The levels of resistance detected in E. coli strains isolated from wild boar were statistically different for ampicillin and co-trimoxasol. According
to NRI cut-offs, 10% of the population showed a non-wild-type phenotype against at least one antibiotic, also including tetracycline (9%), cotrimoxazole
(6%), streptomycin (4%), ampicillin (2%) and amoxicillin/clavulanic acid (1%). Considering this parameter of comparison, no
statistically different levels of resistance were identified between E. coli recovered from the three wild ungulates. Screening of Salmonella spp.,
which can be potentially pathogenic, was also performed, revealing that its prevalence was very low (1.5%). The study demonstrated that wild
ungulates from Portugal are also reservoirs of antibiotic-resistant bacteria
Development of an embryotoxicity test for Enchytraeus crypticus: the effect of Cd
No full textThe existing standard enchytraeid reproduction test (ERT) concerns the assessment of effects on survival
and reproduction. In the present study we optimized and propose an embryotoxicity test using
Enchytraeus crypticus. Cadmium (Cd) was used as a test substance. Endpoints evaluated were embryo
development, number of embryonic structures, Calcium (Ca) channels quantification and hatching success
with macroscopic monitoring, histological and immunohistochemistry analysis. Results showed that
Cd is embryotoxic for this species, causing a decrease in the hatching success (EC50 = 3.1 mg/kg), a delay
or disruption in formation of embryonic structures depending on concentrations (<5 mg Cd/kg or
P16 mg Cd/kg). Results from immunohistochemistry suggest a competitive binding between Cd and
Ca for Ca channels, resulting in changes in Ca homeostasis. The use of the E. crypticus embryotoxicity test
with the combination of histological and immunohistological tools provided a good option towards
mechanistic information enhancing the importance of these tests to evaluate the hazard of chemicals
and possible use in risk assessment
Functional differences in the allometry of the water, carbon and nitrogen content of gelatinous organisms
No full textWe have supplemented available, concurrent measurements of fresh weight (W, g) and body carbon (C, g) (46 individuals, 14 species) and nitrogen (N, g) (11 individuals, 9 species) of marine gelatinous animals with data obtained during the global ocean MALASPINA 2010 Expedition (totalling 267 individuals and 33 species for the W versus C data; totalling 232 individuals and 31 species for the N versus C data). We then used those data to test the allometric properties of the W versus C and N versus C relationships. Overall, gelatinous organisms contain 1.13 ± 1.57% of C (by weight, mean ± SD) in their bodies and show a C:N of 4.56 ± 2.46, respectively, although estimations can be improved by using separate conversion coefficients for the carnivores and the filter feeders. Reduced major axis regression indicates that W increases isometrically with C in the carnivores (cnidarians and ctenophores), implying that their water content can be described by a single conversion coefficient of 173.78 gW(g C)−1, or a C content of 1.17 ± 1.90% by weight, although there is much variability due to the existence of carbon-dense species. In contrast, W increases more rapidly than C in the filter feeders (salps and doliolids), according to a power relationship W = 446.68C1.54. This exponent is not significantly different from 1.2, which is consistent with the idea that the watery bodies of gelatinous animals represent an evolutionary response towards increasing food capture surfaces, i.e. a bottom-up rather than a top-down mechanism. Thus, the available evidence negates a bottom-up mechanism in the carnivores, but supports it in the filter feeders. Last, N increases isometrically with C in both carnivores and filter feeders with C:N ratios of 3.89 ± 1.34 and 4.38 ± 1.21, respectively. These values are similar to those of compact, non-gelatinous organisms and reflect a predominantly herbivorous diet in the filter feeders, which is confirmed by a difference of one trophic level between filter feeders and carnivores, according to stable N isotope enrichment data
Response of intertidal benthic microalgal biofilms to a coupled light-temperature stress: evidence for latitudinal adaptation along the Atlantic coast of Southern Europe
No full textAlthough estuarine microphytobenthos (MPB) is frequently
exposed to excessive light and temperature
conditions, little is known on their interactive effects
on MPB primary productivity. Laboratory and in situ
experiments were combined to investigate the shortterm
joint effects of high light (HL) and high temperature
(37°C versus 27°C) on the operating efficiency of
photoprotective processes [vertical migration versus
non-photochemical quenching (NPQ)] exhibited by
natural benthic diatom communities from two intertidal
flats in France (FR) and Portugal (PT). A clear
latitudinal pattern was observed, with PT biofilms
being more resistant to HL stress, regardless the
effect of temperature, and displaying a lower relative
contribution of vertical migration to photoprotection
and a stronger NPQ in situ. However, higher temperature
leads to comparable effects, with photoinhibition
increasing to about three times (i.e. from 3% to 10%
and from 8% to 22% in PT and FR sites respectively).
By using a number of methodological novelties in
MPB research (lipid peroxidation quantification, Lhcx
proteins immunodetection), this study brings a physiological
basis to the previously reported depression
of MPB photosynthetic productivity in summer. They
emphasize the joint role of temperature and light in
limiting, at least transiently (i.e. during emersion),
MPB photosynthetic activity in situ
LORE, a decision support tool for location, routing and location-routing problems
No full textLOcation Routing Exploration (LORE) is a decision support tool for addressing location, routing and location-routing problems. In this paper the LORE tool will be presented, and its main characteristics addressed. Among the main features of the tool is the ability to support a variety of problems currently being studied in the location and routing literature (due to the proposed data structure), and the graphical user interface (GUI). The data structure will be presented being provided an explanation on how it can support related problems. The GUI main goal is not only to aid the solution-finding process but also to foster greater insight into the problem(s) at hand. To that extent, the GUI, developed to fit the target user’s profile and intended tasks, is presented, namely data input and visualization features
Centros opticamente activos em filmes de GaN: a banda amarela
No full textMestrado em Física AplicadaO estudo dos nitretos, de elementos do grupo III, semicondutores transparentes no
visível, tem registado nos últimos anos um enorme avanço, dado o crescente interesse pelos
mesmos, quer na forma de slmes finos, quer em monocristais.
Estes materiais apresentam-se como fortes candidatos para servirem de base a
componentes de semicondutores a operarem na zona da radiação electromagnética do azul
e ultra-violeta, zonas estas não abrangidas pelos semicondutores convencio&is. Assim
espera-se um enorme impacto destes materiais na electrónica e optoelectrónica, em
aplicações gráficas e de memórias de alta densidade. As suas fortes ligações atómicas torna-
-os também candidatos para aplicações em equipamentos de elevada potência e elevada
temperatura, sendo também resistentes à corrosão.
Neste trabalho efectuou-se o estudo das emissões observadas sensivelmente a meio da
banda de emissões proibidas (adiante designado como "gap") em epicamadas de GaN
crescido sobre carboneto de silício e safira. A caracterização das amostras foi realizada
utilizando como técnicas experimentais a espectroscopia em estado estacionário e resolvido
no tempo, e catodoluminescência. A dependência com a temperatura da intensidade e os
tempos de vida das emissões em estudo, permitiram estabelecer modelos de recombinação
dos diferentes centros ópticos