Filmes comestíveis de alginato e goma de cajueiro.

bitstream/item/42116/1/COT11005.pd

Effect of batch and fed-batch growth modes on biofilm formation by Listeria monocytogenes at different temperatures

The influence of Listeria monocytogenes (L. monocytogenes) biofilm formation feeding conditions (batch and fed-batch) at different temperatures on biofilm biomass and activity was determined. Biofilm biomass and cellular metabolic activity were assessed by Crystal Violet (CV) staining and 2,3-bis(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide inner salt (XTT) colorimetric method, respectively. Live/Dead staining was also performed in order to get microscopic visualization of the different biofilms. Results revealed that at refrigeration temperature (4°C) a higher amount of biofilm was produced when batch conditions were applied, while at higher temperatures the fed-batch feeding condition was the most effective on biofilm formation. Moreover, independently of the temperature used, biofilms formed under fed-batch conditions were metabolically more active than those formed in batch mode. In conclusion, this work shows that different growth modes significantly influence L. monocytogenes biofilm formation on abiotic surfaces as well as the metabolic activity of cells within biofilms.Fundação para a Ciência e a Tecnologia (FCT) - PPCDT/AGR/59358/2004, SFRH/ BD/28887/2006, SFRH/BPD/26803/200

Effects of clays on spin-spin relaxation: a route for non-invasive total clay content quantification

Clay minerals are important components of sandstone rocks, due to their significant role on petrophysical properties like porosity and permeability. These minerals have a particular impact on Nuclear Magnetic Resonance measurements since the iron contained on clays generates internal gradients which directly affect the transverse relaxation. Here, we apply a methodology recently developed to a set of 20 sandstones, with varying clay content and mineralogy, in order to estimate the total clay content by using the effect of internal gradients on transverse relaxation. Based on these measurements, we propose a geochemical rock typing from quantities determined by our measurements, namely the total clay content and porosity

Staphylococcus epidermidis glucose uptake in biofilm versus planktonic cells

The aim of this work was to compare the glucose uptake of biofilms formed by four different Staphylococcus epidermidis strains as well as to compare between sessile and planktonic cells of the same strain. Biofilm cells showed a lower level of glucose uptake compared to planktonic cells. Moreover, glucose uptake by cells in the sessile form was strongly influenced by biofilm composition. Therefore, this work helps to confirm the phenotypic variability of S. epidermidis strains and the different behaviour patterns between sessile and free cells.Fundação para a Ciência e a Tecnologia (FCT) - POCTI/ESP/42688/2001; SFRH/BD/19265/2004

Dietary tryptophan deficiency and its supplementation compromises inflammatory mechanisms and disease resistance in a teleost fish

Tryptophan participates on several physiological mechanisms of the neuroendocrine-immune network and plays a critical role in macrophages and lymphocytes function. This study intended to evaluate the modulatory effects of dietary tryptophan on the European seabass (Dicentrarchus labrax) immune status, inflammatory response and disease resistance to Photobacterium damselae piscicida. A tryptophan deficient diet (NTRP); a control diet (CTRL); and two other diets supplemented with tryptophan at 0.13% (TRP13) and 0.17% (TRP17) of feed weight were formulated. Fish were sampled at 2 and 4 weeks of feeding and the remaining were i.p. injected with Phdp (3 × 106 cfu/fish) at 4 weeks and the inflammatory response (at 4, 24, 48 and 72 hours post-infection) as well as survival were evaluated. Results suggest that fish immune status was not altered in a tryptophan deficient scenario whereas in response to an inflammatory insult, plasma cortisol levels increased and the immune cell response was compromised, which translated in a lower disease resistance. When dietary tryptophan was offered 30% above its requirement level, plasma cortisol increased and, in response to bacterial infection, a decrease in lymphocytes, monocytes/macrophages and several immune-related genes was observed, also compromising at some degree fish disease resistance.This work was partially supported by Projects ALISSA (reference ALG-01-0247-FEDER-3520), IF/00197/2015 and INFLAMMAA (reference 02/SAICT/2017/032349), financed by Portugal and the European Union through FEDER, COMPETE 2020 and CRESC Algarve 2020, in the framework of Portugal 2020, and through the COMPETE and Operational Human Potential Programmes and national funds through Fundação para a Ciência e a Tecnologia (FCT, Portugal). M. Machado and B. Costas were supported by FCT, Portugal (SFRH/ BD/108243/2015 and IF/00197/2015, respectively). The authors also acknowledge Dr. Nuno Santos (i3S/IBMC) for critically reviewing the manuscript

Dietary methionine improves the european seabass (dicentrarchus labrax) immune status, inflammatory response, and disease resistance

Methionine presents a pivotal role in the regulation of many cellular events with crucial impact on the immune system, such as in processes involved in the control of inflammation and polyamines synthesis. Accordingly, the present study aimed to assess the modulatory effects of dietary methionine on the European seabass (Dicentrarchus labrax) immune status, inflammatory response and disease resistance to Photobacterium damselae subsp. piscicida (Phdp). For this purpose, fish were randomly distributed in three independent groups (three replicates per group) and each was fed the corresponding diet: a control diet (CTRL) formulated to meet the established amino acid requirements for the species; a diet supplemented with methionine at 0.5% of feed weight relative to the CTRL diet (8.2% of methionine concentration above CTRL); and one supplemented with methionine at 1% of feed weight to the CTRL diet (11.8% of methionine concentration above CTRL). To evaluate the immune status of fish fed with each of the diets before being submitted to bacterial infection fish were sampled from each group at 2 and 4 weeks after the beginning of feeding. Non- sampled fish were injected intraperitoneally with Phdp (5 × 103 cfu/fish) at 4 weeks after initiation of feeding and the inflammatory response (at 4, 24, and 48 h post-infection) and survival (lasting 21 days post-infection) evaluated. Fish hematological profile, peripheral cell dynamics, plasma humoral immune parameters, leucocyte migration to the inflammatory focus and head-kidney gene expression were evaluated. Results show that methionine dietary supplementation improves seabass cellular immune status without evidence of activation of pro-inflammatory mechanisms. Additionally, the observed enhanced immune status provided by methionine supplementation translated into an improved immune response to infection, as higher cellular differentiation/proliferation and recruitment toThis work was partially supported by Projects ALISSA (reference ALG-01-0247-FEDER-3520) and F/00197/2015, financed by Portugal and the European Union through FEDER, COMPETE 2020 and CRESC Algarve 2020, in the framework of Portugal 2020, and through the COMPETE and Operational Human Potential Programmes and national funds through Fundação para a Ciência e a Tecnologia (FCT, Portugal). MM and BC were supported by FCT, Portugal (SFRH/BD/108243/2015 and IF/00197/2015, respectively). The authors also acknowledge Dr. Nuno Santos and Dr. Ana do Vale (i3S/IBMC) support during the study and for critically reviewing the manuscript

Alterações na transmitância UV-Visível induzidas pelo uso de lentes de contacto de silicone-hidrogel

Fundação para a Ciência e a Tecnologia (FCT) through Centro de Física da U