Papers by Maria João Peixoto
Frontiers in Marine Science, 2014
Scientific Reports, 2019
European seabass (Dicentrarchus labrax) production is often hampered by bacterial infections such... more European seabass (Dicentrarchus labrax) production is often hampered by bacterial infections such as photobacteriosis caused by Photobacterium damselae subsp. piscicida (Phdp). Since diet can impact fish immunity, this work investigated the effect of dietary supplementation of 5% Gracilaria sp. aqueous extract (GRA) on seabass antioxidant capacity and resistance against Phdp. After infection, mortality was delayed in fish fed GRA, which also revealed increased lysozyme activity levels, as well as decreased lipid peroxidation, suggesting higher antioxidant capacity than in fish fed a control diet. Dietary GRA induced a down-regulation of hepatic stress-responsive heat shock proteins (grp-78, grp-170, grp-94, grp-75), while bacterial infection caused a down-regulation in antioxidant genes (prdx4 and mn-sod). Diet and infection interaction down-regulated the transcription levels of genes associated with oxidative stress response (prdx5 and gpx4) in liver. In head-kidney, GRA led to an ...
Fish & Shellfish Immunology, 2018
This study aimed to evaluate the protective effects of four autochthonous bacteria isolated from ... more This study aimed to evaluate the protective effects of four autochthonous bacteria isolated from juvenile sole (Solea senegalensis) intestine as dietary probiotic supplement against bacterial pathogen infection and handling/ transport stressors. Growth performance and immune responses were evaluated after 85 days of feeding trial. Sole (IBW = 16.07 ± 0.11 g) were fed six experimental diets, a control diet (CTRL, without the dietary probiotic supplementation), and five diets supplemented with probiotic bacteria: PB1 (Shewanella hafniensis), PB2 (Enterococcus raffinosus), PB3 (Shewanella hafniensis + Arthrobacter soli), PB4 (Pseudomonas protegens + Arthrobacter soli) and PB5 (Shewanella hafniensis + Arthrobacter soli + Enterococcus raffinosus). All bacteria were selected based on their in vitro antimicrobial activity. After the growth trial, fish were submitted to a stress factor (transport) and then each dietary group was divided in two additional groups: non-infected (placebo) and infected with Photobacterium damselae subsp. piscicida. Immune and antioxidant responses were evaluated at day 10 post-infection. In infection trial A, fish were infected on the same day of transport, whereas in trial B fish were infected after a 7-day recovery from the transport stress. At the end of the feeding trial, fish fed with PB2 and PB4 showed lower final body weight when compared with the other dietary groups. Respiratory burst activity and nitric oxide production were not affected by probiotic supplementation. Fish fed with PB5 presented lower peroxidase activity compared to CTRL. Lysozyme and alternative complement pathway activity (ACH50) showed no significant differences between treatments. The innate immune responses were significantly affected after handling stress and bacterial infection. In trial A, the ACH50 levels of infected fish were significantly lower than the placebo groups. On the other hand, in trial B fish infected with Pdp demonstrated higher ACH50 levels when compared to placebos. Peroxidase levels were strongly modulated by bacterial infection and handling stress. In trials A and B, infection had a clear downgrade effect in peroxidase levels. Lipid peroxidation, catalase, glutathione S-transferase and glutathione reductase were altered by both bacterial infection and transport. Overall, dietary probiotic supplementation did not influence growth performance of sole. The immune and oxidative defenses of sole responded differently to infection depending on the probiotic and the synergy between pathogen infection and transport.
Comparative Biochemistry and Physiology Part B: Biochemistry and Molecular Biology, 2019
The replacement of fish oil (FO) with other lipid sources (e.g. animal fats, AF) in aquafeeds imp... more The replacement of fish oil (FO) with other lipid sources (e.g. animal fats, AF) in aquafeeds improves the sustainability of aquaculture, even though alternatives have different fatty acid (FA) profiles. FO contains a higher proportion of long-chain polyunsaturated fatty acids (LC-PUFAs) than AF. LC-PUFAs have key physiological roles, despite limited biosynthetic capacity in marine fish. Therefore, replacing FO in feeds may limit physiological responses when fish face environmental challenges such as an acute change in salinity.
Comparative biochemistry and physiology. Part B, Biochemistry & molecular biology, Jan 16, 2017
Dietary ion content is known to alter the acid-base balance in freshwater fish. The current study... more Dietary ion content is known to alter the acid-base balance in freshwater fish. The current study investigated the metabolic impact of acid-base disturbances produced by differences in dietary electrolyte balance (DEB) in the meagre (Argyrosomus regius), an euryhaline species. Changes in fish performance, gastric chyme characteristics, pH and ion concentrations in the bloodstream, digestive enzyme activities and metabolic rates were analyzed in meagre fed ad libitum two experimental diets (DEB 200 or DEB 700mEq/kg) differing in the Na2CO3 content for 69days. Fish fed the DEB 200 diet had 60-66% better growth performance than the DEB 700 group. Meagre consuming the DEB 200 diet were 90-96% more efficient than fish fed the DEB 700 diet at allocating energy from feed into somatic growth. The pH values in blood were significantly lower in the DEB 700 group two hours after feeding when compared to DEB 200, indicating that acid-base balance in meagre was affected by electrolyte balance in...
Lipids, 2016
The meagre (Argyrosomus regius) is taking on increasing importance in the aquaculture industry. I... more The meagre (Argyrosomus regius) is taking on increasing importance in the aquaculture industry. In view of the limited supply of fish oil (FO) as a feed ingredient, the study of the capacity to biosynthesize long-chain polyunsaturated fatty acids (LC-PUFA) from alternative dietary oil sources is important. We analyzed changes in fatty acid (FA) desaturase 2 (fads2) and FA elongase 5 (elovl5) mRNA levels in livers and brains in response to FO replacement with a blend of vegetable oils (VO) and selenium (Se) supplementation. Fish were fed for 60 days with either a diet containing FO or a diet including VO, each supplemented or not with organic Se. Results showed that fads2 and elovl5 transcription was higher in liver when fish were fed VO diets. The brain mRNA levels of both genes were not affected by the dietary replacement of FO by VO. FA composition in the liver and skeletal muscle was altered by FO replacement, particularly by decreasing eicosapentaenoic acid and docosahexaenoic acid contents. The α-linolenic, linoleic, and arachidonic acid contents increased in both liver and brain of fish fed VO diets. The effect of Se supplementation on lipid metabolism was evident only in fish fed FO, showing a decrease in the transcription of hepatic fads2. Results indicate that the total replacement of FO by VO in diets modulates the expression of genes involved in LC-PUFA biosynthesis in meagre, affecting the FA profile of the fish flesh.
BMC Research Notes
Objective Diabetic foot infection (DFI) represents a major healthcare burden, for which treatment... more Objective Diabetic foot infection (DFI) represents a major healthcare burden, for which treatment is challenging owing to the pathophysiological alterations intrinsic to diabetes and the alarming increase of antimicrobial resistance. Novel therapies targeting DFI are therefore a pressing research need for which proper models of disease are required. Results Here, we present an optimized diabetic mouse model of methicillin-resistant Staphylococcus aureus (MRSA)-infected wounds, that resemble key features of DFI, such as pathogen invasion through wound bed and surrounding tissue, necrosis, persistent inflammation and impaired wound healing. Thus, in a time-efficient manner and using simple techniques, this model represents a suitable approach for studying emerging therapies targeting DFI caused by MRSA.
Frontiers in Marine Science, 2014
Frontiers in Marine Science, 2014
Frontiers in Marine Science, 2014
Human Mutation
Understanding the role of common polymorphisms in modulating the clinical phenotype when they co-... more Understanding the role of common polymorphisms in modulating the clinical phenotype when they co-occur with a disease-causing lesion is of critical importance in medical genetics. We explored the impact of apparently neutral common polymorphisms, using the gene encoding the urea cycle enzyme, ornithine transcarbamylase (OTC), as a model system. Distinct combinations of genetic backgrounds embracing two missense polymorphisms were created in cis with the pathogenic p.Arg40His replacement. In vitro enzymatic assays revealed that the polymorphic variants were able to modulate OTC activity both in the presence or absence of the pathogenic lesion. First, we found that the combination of the minor alleles of polymorphisms p.Lys46Arg and p.Gln270Arg significantly enhanced enzymatic activity in the wild-type protein. Second, enzymatic assays revealed that the minor allele of the p.Gln270Arg polymorphism was capable of ameliorating OTC activity when combined in cis with the pathogenic p.Arg40His replacement. Structural analysis predicted that the minor allele of the p.Gln270Arg polymorphism would serve to stabilize the OTC wild-type protein, thereby corroborating the results of the experimental assays. Our findings demonstrate the potential importance of cisinteractions between common polymorphic variants and pathogenic missense mutations and illustrate how standing genetic variation can modulate protein function.
Emerging Microbes & Infections
Buruli ulcer (BU) is a devastating skin mycobacterial infection characterized by extensive cell d... more Buruli ulcer (BU) is a devastating skin mycobacterial infection characterized by extensive cell death, which was previously suggested to be mediated by Bcl2-like protein 11 (BIM, encoded by the BCL2L11 gene). We here report the association of genetic variants in BCL2L11 with ulcerative forms of the disease in a cohort of 618 Beninese individuals. Our results show that regulation of apoptosis in humans contributes to BU lesions associated with worse prognosis, prompting for further investigation on the implementation of novel methods for earlier identification of at-risk patients.
Effects of dietary Gracilaria sp. and Alaria sp. supplementation on growth performance, metabolic... more Effects of dietary Gracilaria sp. and Alaria sp. supplementation on growth performance, metabolic rates and health in meagre (Argyrosomus regius) subjected to pathogen infection
Frontiers in Marine Science, 2014
Journal of Applied Phycology, 2016
Aquaculture Reports, 2016
This work aimed to appraise growth performance, digestive capacity and immune and stress responsi... more This work aimed to appraise growth performance, digestive capacity and immune and stress responsiveness in European seabass (Dicentrarchus labrax) when fed diets supplemented with seaweeds. A control diet (without supplementation) was tested against 6 practical diets supplemented either with Gracilaria spp., Ulva spp., or Fucus spp., at 2.5 or 7.5% levels, plus an additional diet with a blend of the three seaweeds , each supplemented at 2.5% (Mix). Seabass juveniles (24.0 ± 6.3 g) were fed the experimental diets for 84 days. Dietary seaweed supplementation had no effect on growth rate (DGI: 1.0–1.1), voluntary feed intake (11.3–12.6 g kg −1 ABW −1 day −1), feed conversion ratio (FCR: 1.2–1.4) and protein efficiency ratio (PER: 1.5–1.8). Lipase activity was significantly higher in fish fed Mix diet when compared to control (P < 0.05). Glutathione peroxidase (GPx) was significantly affected by seaweeds presence regardless its level of supplementation (P < 0.05). The innate immune system was significantly altered by dietary seaweed supplementation (P < 0.05). Fish fed the 7.5% seaweed supplemented diets had a significant decrease in the ACH50 level, when compared to fish fed 2.5% seaweed supplemented diets (P < 0.05). Moreover, a combined effect of seaweed and supplementation level significantly affected lysozyme (LYS) activity (P < 0.05). Fish fed diet with Ulva at 2.5% had an increase in LYS when compared to fish fed control and Ulva at 7.5% diets. Overall, our results indicate that the use of dietary seaweed supplementation improves immune and antioxidant responses in European seabass without compromising growth performance.
Journal of Applied Phycology, 2015
Increasing levels of a mixture of Ulva spp. (Ulva rigida and Ulva lactuca) produced in an integra... more Increasing levels of a mixture of Ulva spp. (Ulva rigida and Ulva lactuca) produced in an integrated multitrophic aquaculture (IMTA) system were evaluated in Nile tilapia. A control diet (CTRL) was compared with two experimental isonitrogenous (36 %) and isoenergetic (20 kJ g −1) diets containing 5 % (U5) and 10 % (U10) of Ulva spp. meal. Duplicate groups of 18 fish (255 g initial body weight) were reared at 25°C and fed each diet for 68 days to evaluate carotenoid deposition, flesh organoleptic properties and immunological response. By the end of the trial, all groups of fish showed similar final body weight and specific growth rate. Whole body composition was also similar among treatments. The dietary incorporation of Ulva spp. meal increased total carotenoid content in the skin, with fish fed U5 displaying significantly higher levels (6.5 μg g −1) than the CRTL (1.4 μg g −1). No carotenoids could be found in tilapia muscle. Muscle colour determined using a spectrocolorimeter indicated that tilapia fillets from fish fed U10 showed the highest lightness (highest L* value) and yellowness (less negative b* value), but the lowest redness (lowest a* value). Furthermore, sensory attributes of flesh showed no significant effects of dietary treatments on visual, olfactory, texture and flavour parameters, with the exception of sour parameter that was lowest in U10-fed tilapia. The dietary inclusion of Ulva spp. meal had no beneficial effect on lysozyme or peroxidase activity, but the complement activity (ACH50), an important component of innate immune system in fish, increased concomitantly with the dietary inclusion level of Ulva spp. meal. The inclusion of Ulva spp. meal in diets for Nile tilapia seems to be possible up to 10 % without major effects on growth performance or flesh organoleptic properties but enhancing the innate immune response of the fish.
Aquaculture Research, 2015
ABSTRACT This study was conducted to evaluate the effects of dietary probiotic supplementation on... more ABSTRACT This study was conducted to evaluate the effects of dietary probiotic supplementation on growth performance, fish welfare, sensory evaluation, freshness during ice storage and changes in intestinal microbiota of rainbow trout (Oncorhynchus mykiss). The 9-week feeding trial was conducted in cages under commercial conditions during the winter season, when water temperature decreased from 14°C to 7°C. Fish were fed either a diet without probiotic supplementation (control) or with 0.2% (2 × 109 CFU kg−1 diet) of multi-strain probiotic bacteria (Bacillus sp., Pediococcus sp., Enterococcus sp., Lactobacillus sp.). Fish weight was recorded at 0, 2, 4, 6 and 9 weeks. Growth performance was not affected by dietary probiotic supplementation. Alternative complement activity (ACH50) was significantly higher in fish fed the diet with probiotic (58.4 ± 3.7 units mL−1) than in the control group (46.9 ± 3.1 units mL−1) (P = 0.03). Several biochemical markers were altered by the dietary treatment. 7-ethoxyresorufin-O-deethylase (EROD) (P < 0.01), glutathione S-transferase (GST) (P < 0.001), glutathione peroxidase (GPx) (P < 0.05) increased and lipid peroxidation (LP) (P < 0.01) decreased with dietary probiotic supplementation. Flesh quality and shelf-life of fish stored on ice was not affected by dietary probiotic supplementation. Probiotic supplementation had a limited effect on the intestinal microbiota. Signal strength of the observed operational taxonomic units (OTUs) differed between the control and treatment samples and could indicate variations in the abundance of certain OTUs. Microbiota adhering to the intestinal mucus varied between sampling points, indicating that changes were associated with water temperature.
Frontiers in Marine Science, 2014
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Papers by Maria João Peixoto