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Papers by Alexandre Da Cunha

International journal of systematic and evolutionary microbiology, 2018

An isolate, designated SPSPC-11, with an optimum growth temperature of about 50 °C and an optimum... more An isolate, designated SPSPC-11, with an optimum growth temperature of about 50 °C and an optimum pH for growth between 7.5 and 8.0, was recovered from a hot spring in central Portugal. Based on phylogenetic analysis of its 16S rRNA sequence, the new organism is most closely related to the species of the genus Thermonema but with a pairwise sequence similarity of <85 %. The isolate was orange-pigmented, formed non-motile long filaments and rod-shaped cells that stain Gram-negative. The organism was strictly aerobic, oxidase-positive and catalase-positive. The major fatty acids were iso-C15:0, iso-C15 : 0 2-OH and iso-C17 : 0 3-OH. The major polar lipids were one aminophospholipid, two aminolipids and three unidentified lipids. Menaquinone 7 was the major respiratory quinone. The DNA G+C content of strain SPSPC-11 was 37.6 mol% (draft genome sequence). The high quality draft genome sequence corroborated many of the phenotypic characteristics of strain SPSPC-11. Based on genotypic,...

Microscopy and Microanalysis, 2016

Mannitol oxidase catalyses the oxidation of D-mannitol to produce the sugar mannose, releasing hy... more Mannitol oxidase catalyses the oxidation of D-mannitol to produce the sugar mannose, releasing hydrogen peroxide. This enzyme was detected in the digestive gland and digestive tract of some herbivorous gastropods, suggesting a role in metabolization of mannitol contained in their foodstuff [1, 2, 3]. Mannitol is a 6 carbon polyalcohol present in algae, fungi and plants. Therefore, it seems that herbivorous gastropods get nutritional benefits from the ingestion of polyalcohols present in algae and plants due to enzymes that convert these compounds into sugars [1]. Cell fractionation studies revealed that in the digestive gland of terrestrial gastropods mannitol oxidase is associated with a special kind of tubules with a diameter of 40 nm [3]. But, so far, most studies about mannitol oxidase were performed with terrestrial gastropods. To extend existing knowledge, this enzyme was investigated in the digestive gland of the marine gastropods Aplysia depilans, Bulla striata, Siphonaria pectinata and Onchidella celtica, as well as in the garden snail Cornu aspersum (=Helix aspersa) and the land slug Lehmannia valentiana. For histochemical location of mannitol oxidase digestive gland samples were frozen in liquid nitrogen. Cryostat sections 12 µm thick on glass slides coated with APES were air dried for about 1 hour before being introduced in reaction medium. The reaction medium adapted from previously published methods [1] contained 0.5 mg/ml 3-3'-diaminobenzidine (DAB), 0.25 mg/ml horseradish peroxidase (50 U/ml) and 50 mM D-mannitol in 50 mM phosphate buffer pH 7.5. Control sections were incubated in medium without mannitol. Sections were incubated for about 2 hours at 30ºC. Mannitol oxidase activity was also assessed by biochemical methods. For ultrastructural studies digestive gland samples were fixed with 2.5% glutaraldehyde and 4% formaldehyde in cacodylate buffer, postfixed with osmium tetroxide, dehydrated and embedded in Epon. In cryostat sections, digestive gland cells containing mannitol oxidase were stained brown due to DAB oxidation (Fig. 1 A-C). In control sections reaction was not observed in digestive gland cells (Fig. 1 D), but in other tissues unspecific reactions can occur. Biochemical assays also showed that all these six herbivorous species contain mannitol oxidase in the digestive gland. Enzyme activity was lower in B. striata and S. pectinata, being much higher in O. celtica and L. valentiana, and presented an intermediate value in the digestive gland of A. depilans and C. aspersum. The tubular structures typically associated with mannitol oxidase [3] were found in digestive gland cells of A. depilans, B. striata, C. aspersum and L. valentiana (Fig. 1 E-F). The tubules are located inside rough endoplasmic reticulum cisternae in A. depilans, while in B. striata, C. aspersum and L. valentiana they are found within smooth membrane cisternae (Fig. 1 E). On the other hand, in S. pectinata and O. celtica these tubules were not observed. Thus, at least in marine gastropods, mannitol oxidase is not always associated with intracisternal tubules even in species with a high mannitol oxidase activity such as O. celtica.

Journal of Molluscan Studies, 2015

The salivary glands of the cephalaspideans Philine quadripartita (Philinidae), Aglaja tricolorata... more The salivary glands of the cephalaspideans Philine quadripartita (Philinidae), Aglaja tricolorata (Aglajidae) and Haminoea navicula (Haminoeidae) were studied by light and electron microscopy to investigate relationships between diet, phylogeny and morphofunctional features of these glands. In herbivores such as H. navicula the posterior end of the long ribbon-shaped salivary glands is attached to the gizzard, whereas in P. quadripartita and A. tricolorata these glands are shorter and their posterior end is unattached. The salivary glands of the carnivorous cephalaspidean P. quadripartita contains three types of secretory cells. Granular mucocytes and vacuolated mucocytes, both secreting acid polysaccharides, were much more abundant than the granular cells secreting proteins associated with neutral polysaccharides. The same cell types were recognized in the salivary glands of H. navicula, but in this species the granular cells are much smaller and even less abundant. The salivary glands of A. tricolorata contain different secretory cells, which were named cells with dense vacuoles, alveolar cells and granular cells. The first two produce proteins and acid polysaccharides, while granular cells contain proteins and neutral polysaccharides. Based on these results and previously published data, it can be said that histologically the salivary glands of the carnivorous cephalaspidean P. quadripartita are much more similar to the salivary glands of herbivorous cephalaspideans (Bulla striata and H. navicula) and other herbivorous euopisthobranchs (Aplysia depilans), than to the salivary glands of aglajids (A. tricolorata and Philinopsis depicta) in which mucocytes are absent. Thus, having a herbivorous or a carnivorous diet by itself seems not to have been a major driving factor on the histology of salivary glands in cephalaspideans. The digestive system of aglajids differs from that of other carnivorous cephalaspideans, not only in the histology of salivary glands but also in other aspects such as absence of a gizzard, and the lack of a radula in all but one genus. Concerning the morphology of the digestive system, aglajids are highly derived cephalaspideans.

The Journal of pathology, Jan 15, 2015

Metabolic adaptation is considered an emerging hallmark of cancer whereby cancer cells exhibit hi... more Metabolic adaptation is considered an emerging hallmark of cancer whereby cancer cells exhibit high rates of glucose consumption with consequent lactate production. To ensure rapid efflux of lactate, most cancer cells express high levels of monocarboxylate transporters (MCTs), which therefore may constitute suitable therapeutic targets. The impact of MCT inhibition, along with the clinical impact of altered cellular metabolism during prostate cancer (PCa) initiation and progression, has not been described. Using a large cohort of human prostate tissues of different grades, in silico data, in vitro and ex vivo studies, we demonstrate the metabolic heterogeneity of PCa and its clinical relevance. We show an increased glycolytic phenotype in advanced stages of prostate cancer, and its correlation with poor prognosis. Finally, we present evidence supporting MCTs as suitable targets in PCa, affecting not only cancer cell proliferation and survival but also the expression of a number of H...

In order to obtain more data for a comparative analysis of the digestive system in opisthobranchs... more In order to obtain more data for a comparative analysis of the digestive system in opisthobranchs, the stomach and intestine of Bulla striata were studied with light and electron microscopy. A 3D-model of the stomach and its connections with the posterior oesophagus, digestive gland ducts and intestine was created from a series of histological sections. The U-shaped stomach is just a segment of the digestive tube without any external distinction from

BMC Biochemistry, 2003

Background: This study was aimed primarily at testing in the liver of brown trout (Salmo trutta) ... more Background: This study was aimed primarily at testing in the liver of brown trout (Salmo trutta) spectrophotometric methods previously used to measure the activities of catalase and hydrogen peroxide producing oxidases in mammals. To evaluate the influence of temperature on the activities of those peroxisomal enzymes was the second objective. A third goal of this work was the study of enzyme distribution in crude cell fractions of brown trout liver. Results: The assays revealed a linear increase in the activity of all peroxisomal enzymes as the temperature rose from 10° to 37°C. However, while the activities of hydrogen peroxide producing oxidases were strongly influenced by temperature, catalase activity was only slightly affected. A crude fraction enriched with peroxisomes was obtained by differential centrifugation of liver homogenates, and the contamination by other organelles was evaluated by the activities of marker enzymes for mitochondria (succinate dehydrogenase), lysosomes (aryl sulphatase) and microsomes (NADPH cytochrome c reductase). For peroxisomal enzymes, the activities per mg of protein (specific activity) in liver homogenates were strongly correlated with the activities per g of liver and with the total activities per liver. These correlations were not obtained with crude peroxisomal fractions. Conclusions: The spectrophotometric protocols originally used to quantify the activity of mammalian peroxisomal enzymes can be successfully applied to the study of those enzymes in brown trout. Because the activity of all studied peroxisomal enzymes rose in a linear mode with temperature, their activities can be correctly measured between 10° and 37°C. Probably due to contamination by other organelles and losses of soluble matrix enzymes during homogenisation, enzyme activities in crude peroxisomal fractions do not correlate with the activities in liver homogenates. Thus, total homogenates will be used in future seasonal and toxicological studies of brown trout peroxisomes.

Microscopy and Microanalysis, 2009

The large macro- and microscopic variability in kidney morphology among fish makes it difficult t... more The large macro- and microscopic variability in kidney morphology among fish makes it difficult to build a “universal” understanding on its function and structure. Species-specific studies are thus needed. Thus, morphological study of brown trout trunk kidney was performed, considering potential seasonal and gender effects.

Microbiology and Immunology, 2011

PNAG is a major component of Staphylococcus epidermidis biofilms involved in intercellular adhesi... more PNAG is a major component of Staphylococcus epidermidis biofilms involved in intercellular adhesion as well as in the interaction of the biofilm with components of the host immune response. Synthesis of PNAG has been found to be regulated by several environmental factors. In the present study, the effect of glucose metabolism-dependent culture medium acidification in PNAG accumulation was evaluated. Established S. epidermidis biofilms were allowed to grow in excess glucose with or without maintained pH conditions. PNAG accumulation in these biofilms was determined by flow cytometry and fluorescence microscopy using wheat germ agglutinin as a fluorescent probe. Biofilms grown in maintained pH conditions presented significantly higher amounts of this polymer as well as higher icaA expression than biofilms grown in acidic pH conditions. Moreover, PNAG accumulation in biofilms grown in non-maintained pH conditions occurred in association with cell death. Overall, we show that glucose metabolism by decreasing the culture pH affects biofilm physiology in respect to PNAG production and cell death. The reported in vitro modulation of PNAG accumulation within S. epidermidis biofilms further highlights the role of environment on determining the biofilm physiological state.

Marine Drugs, 2010

Neurotoxicity induced in fish by domoic acid (DA) was assessed with respect to occurrence of neur... more Neurotoxicity induced in fish by domoic acid (DA) was assessed with respect to occurrence of neurotoxic signs, lethality, and histopathology by light microscopy. Sparus aurata were exposed to a single dose of DA by intraperitoneal (i.p.) injection of 0, 0.45, 0.9, and 9.0 mg DA kg −1 bw. Mortality (66.67 ± 16.67%) was only observed in dose of 9.0 mg kg −1 bw. Signs of neurological toxicity were detected for the doses of 0.9 and 9.0 mg DA kg −1 bw. Furthermore, the mean concentrations (±SD) of DA detected by HPLC-UV in extracts of brain after exposure to 9.0 mg DA kg −1 bw were 0.61 ± 0.01, 0.96 ± 0.00, and 0.36 ± 0.01 mg DA kg −1 tissue at 1, 2, and 4 hours. The lack of major permanent brain damage in S. aurata, and reversibility of neurotoxic signs, suggest that lower susceptibility to DA or neuronal recovery occurs in affected individuals.

International Journal of Systematic and Evolutionary Microbiology, 2011

A Gram-positive, aerobic, non-motile, endospore-forming rod, designated DS22T, was isolated from ... more A Gram-positive, aerobic, non-motile, endospore-forming rod, designated DS22T, was isolated from a drinking-water treatment plant. Cells were catalase- and oxidase-positive. Growth occurred at 15–37 °C, at pH 7–10 and with <8 % (w/v) NaCl (optimum growth: 30 °C, pH 7–8 and 1–3 % NaCl). The major respiratory quinone was menaquinone 7, the G+C content of the genomic DNA was 36.5 mol% and the cell wall contained meso-diaminopimelic acid. On the basis of 16S rRNA gene sequence analysis, strain DS22T was a member of the genus Bacillus. Its closest phylogenetic neighbours were Bacillus horneckiae NRRL B-59162T (98.5 % 16S rRNA gene sequence similarity), Bacillus oceanisediminis H2T (97.9 %), Bacillus infantis SMC 4352-1T (97.4 %), Bacillus firmus IAM 12464T (96.8 %) and Bacillus muralis LMG 20238T (96.8 %). DNA–DNA hybridization, and biochemical and physiological characterization allowed the differentiation of strain DS22T from its closest phylogenetic neighbours. The data supports the...

International Journal of Systematic and Evolutionary Microbiology, 2015

An aerobic, Gram-stain-negative rod, designated strain A2P5T, was isolated from the Douro river, ... more An aerobic, Gram-stain-negative rod, designated strain A2P5T, was isolated from the Douro river, in Porto, Portugal. Cells were catalase- and oxidase-positive. Growth occurred at 15–30 °C, at pH 6–8 and in the presence of 1 % (w/v) NaCl. The major respiratory quinone was Q8, the genomic DNA had a G+C content of 47 ± 1 mol%, and phosphatidylethanolamine, phosphatidylglycerol and diphosphatidylglycerol were amongst the major polar lipids. On the basis of 16S rRNA gene sequence analysis, strain A2P5T was observed to be a member of the family Burkholderiaceae, but could not be identified as a member of any validly named genus. The low levels of 16S rRNA gene sequence similarity to other recognized taxa ( < 91 %), together with the comparative analysis of phenotypic and chemotaxonomic characteristics, supported the proposal of a novel species of a new genus within the family Burkholderiaceae. The name Hydromonas duriensis gen. nov., sp. nov. is proposed. The type strain of Hydromonas ...

Marine Drugs, 2010

Neurotoxicity induced in fish by domoic acid (DA) was assessed with respect to occurrence of neur... more Neurotoxicity induced in fish by domoic acid (DA) was assessed with respect to occurrence of neurotoxic signs, lethality, and histopathology by light microscopy. Sparus aurata were exposed to a single dose of DA by intraperitoneal (i.p.) injection of 0, 0.45, 0.9, and 9.0 mg DA kg −1 bw. Mortality (66.67 ± 16.67%) was only observed in dose of 9.0 mg kg −1 bw. Signs of neurological toxicity were detected for the doses of 0.9 and 9.0 mg DA kg −1 bw. Furthermore, the mean concentrations (±SD) of DA detected by HPLC-UV in extracts of brain after exposure to 9.0 mg DA kg −1 bw were 0.61 ± 0.01, 0.96 ± 0.00, and 0.36 ± 0.01 mg DA kg −1 tissue at 1, 2, and 4 hours. The lack of major permanent brain damage in S. aurata, and reversibility of neurotoxic signs, suggest that lower susceptibility to DA or neuronal recovery occurs in affected individuals.

International journal of systematic and evolutionary microbiology, 2018

An isolate, designated SPSPC-11, with an optimum growth temperature of about 50 °C and an optimum... more An isolate, designated SPSPC-11, with an optimum growth temperature of about 50 °C and an optimum pH for growth between 7.5 and 8.0, was recovered from a hot spring in central Portugal. Based on phylogenetic analysis of its 16S rRNA sequence, the new organism is most closely related to the species of the genus Thermonema but with a pairwise sequence similarity of <85 %. The isolate was orange-pigmented, formed non-motile long filaments and rod-shaped cells that stain Gram-negative. The organism was strictly aerobic, oxidase-positive and catalase-positive. The major fatty acids were iso-C15:0, iso-C15 : 0 2-OH and iso-C17 : 0 3-OH. The major polar lipids were one aminophospholipid, two aminolipids and three unidentified lipids. Menaquinone 7 was the major respiratory quinone. The DNA G+C content of strain SPSPC-11 was 37.6 mol% (draft genome sequence). The high quality draft genome sequence corroborated many of the phenotypic characteristics of strain SPSPC-11. Based on genotypic,...

Microscopy and Microanalysis, 2016

Mannitol oxidase catalyses the oxidation of D-mannitol to produce the sugar mannose, releasing hy... more Mannitol oxidase catalyses the oxidation of D-mannitol to produce the sugar mannose, releasing hydrogen peroxide. This enzyme was detected in the digestive gland and digestive tract of some herbivorous gastropods, suggesting a role in metabolization of mannitol contained in their foodstuff [1, 2, 3]. Mannitol is a 6 carbon polyalcohol present in algae, fungi and plants. Therefore, it seems that herbivorous gastropods get nutritional benefits from the ingestion of polyalcohols present in algae and plants due to enzymes that convert these compounds into sugars [1]. Cell fractionation studies revealed that in the digestive gland of terrestrial gastropods mannitol oxidase is associated with a special kind of tubules with a diameter of 40 nm [3]. But, so far, most studies about mannitol oxidase were performed with terrestrial gastropods. To extend existing knowledge, this enzyme was investigated in the digestive gland of the marine gastropods Aplysia depilans, Bulla striata, Siphonaria pectinata and Onchidella celtica, as well as in the garden snail Cornu aspersum (=Helix aspersa) and the land slug Lehmannia valentiana. For histochemical location of mannitol oxidase digestive gland samples were frozen in liquid nitrogen. Cryostat sections 12 µm thick on glass slides coated with APES were air dried for about 1 hour before being introduced in reaction medium. The reaction medium adapted from previously published methods [1] contained 0.5 mg/ml 3-3'-diaminobenzidine (DAB), 0.25 mg/ml horseradish peroxidase (50 U/ml) and 50 mM D-mannitol in 50 mM phosphate buffer pH 7.5. Control sections were incubated in medium without mannitol. Sections were incubated for about 2 hours at 30ºC. Mannitol oxidase activity was also assessed by biochemical methods. For ultrastructural studies digestive gland samples were fixed with 2.5% glutaraldehyde and 4% formaldehyde in cacodylate buffer, postfixed with osmium tetroxide, dehydrated and embedded in Epon. In cryostat sections, digestive gland cells containing mannitol oxidase were stained brown due to DAB oxidation (Fig. 1 A-C). In control sections reaction was not observed in digestive gland cells (Fig. 1 D), but in other tissues unspecific reactions can occur. Biochemical assays also showed that all these six herbivorous species contain mannitol oxidase in the digestive gland. Enzyme activity was lower in B. striata and S. pectinata, being much higher in O. celtica and L. valentiana, and presented an intermediate value in the digestive gland of A. depilans and C. aspersum. The tubular structures typically associated with mannitol oxidase [3] were found in digestive gland cells of A. depilans, B. striata, C. aspersum and L. valentiana (Fig. 1 E-F). The tubules are located inside rough endoplasmic reticulum cisternae in A. depilans, while in B. striata, C. aspersum and L. valentiana they are found within smooth membrane cisternae (Fig. 1 E). On the other hand, in S. pectinata and O. celtica these tubules were not observed. Thus, at least in marine gastropods, mannitol oxidase is not always associated with intracisternal tubules even in species with a high mannitol oxidase activity such as O. celtica.

Journal of Molluscan Studies, 2015

The salivary glands of the cephalaspideans Philine quadripartita (Philinidae), Aglaja tricolorata... more The salivary glands of the cephalaspideans Philine quadripartita (Philinidae), Aglaja tricolorata (Aglajidae) and Haminoea navicula (Haminoeidae) were studied by light and electron microscopy to investigate relationships between diet, phylogeny and morphofunctional features of these glands. In herbivores such as H. navicula the posterior end of the long ribbon-shaped salivary glands is attached to the gizzard, whereas in P. quadripartita and A. tricolorata these glands are shorter and their posterior end is unattached. The salivary glands of the carnivorous cephalaspidean P. quadripartita contains three types of secretory cells. Granular mucocytes and vacuolated mucocytes, both secreting acid polysaccharides, were much more abundant than the granular cells secreting proteins associated with neutral polysaccharides. The same cell types were recognized in the salivary glands of H. navicula, but in this species the granular cells are much smaller and even less abundant. The salivary glands of A. tricolorata contain different secretory cells, which were named cells with dense vacuoles, alveolar cells and granular cells. The first two produce proteins and acid polysaccharides, while granular cells contain proteins and neutral polysaccharides. Based on these results and previously published data, it can be said that histologically the salivary glands of the carnivorous cephalaspidean P. quadripartita are much more similar to the salivary glands of herbivorous cephalaspideans (Bulla striata and H. navicula) and other herbivorous euopisthobranchs (Aplysia depilans), than to the salivary glands of aglajids (A. tricolorata and Philinopsis depicta) in which mucocytes are absent. Thus, having a herbivorous or a carnivorous diet by itself seems not to have been a major driving factor on the histology of salivary glands in cephalaspideans. The digestive system of aglajids differs from that of other carnivorous cephalaspideans, not only in the histology of salivary glands but also in other aspects such as absence of a gizzard, and the lack of a radula in all but one genus. Concerning the morphology of the digestive system, aglajids are highly derived cephalaspideans.

The Journal of pathology, Jan 15, 2015

Metabolic adaptation is considered an emerging hallmark of cancer whereby cancer cells exhibit hi... more Metabolic adaptation is considered an emerging hallmark of cancer whereby cancer cells exhibit high rates of glucose consumption with consequent lactate production. To ensure rapid efflux of lactate, most cancer cells express high levels of monocarboxylate transporters (MCTs), which therefore may constitute suitable therapeutic targets. The impact of MCT inhibition, along with the clinical impact of altered cellular metabolism during prostate cancer (PCa) initiation and progression, has not been described. Using a large cohort of human prostate tissues of different grades, in silico data, in vitro and ex vivo studies, we demonstrate the metabolic heterogeneity of PCa and its clinical relevance. We show an increased glycolytic phenotype in advanced stages of prostate cancer, and its correlation with poor prognosis. Finally, we present evidence supporting MCTs as suitable targets in PCa, affecting not only cancer cell proliferation and survival but also the expression of a number of H...

In order to obtain more data for a comparative analysis of the digestive system in opisthobranchs... more In order to obtain more data for a comparative analysis of the digestive system in opisthobranchs, the stomach and intestine of Bulla striata were studied with light and electron microscopy. A 3D-model of the stomach and its connections with the posterior oesophagus, digestive gland ducts and intestine was created from a series of histological sections. The U-shaped stomach is just a segment of the digestive tube without any external distinction from

BMC Biochemistry, 2003

Background: This study was aimed primarily at testing in the liver of brown trout (Salmo trutta) ... more Background: This study was aimed primarily at testing in the liver of brown trout (Salmo trutta) spectrophotometric methods previously used to measure the activities of catalase and hydrogen peroxide producing oxidases in mammals. To evaluate the influence of temperature on the activities of those peroxisomal enzymes was the second objective. A third goal of this work was the study of enzyme distribution in crude cell fractions of brown trout liver. Results: The assays revealed a linear increase in the activity of all peroxisomal enzymes as the temperature rose from 10° to 37°C. However, while the activities of hydrogen peroxide producing oxidases were strongly influenced by temperature, catalase activity was only slightly affected. A crude fraction enriched with peroxisomes was obtained by differential centrifugation of liver homogenates, and the contamination by other organelles was evaluated by the activities of marker enzymes for mitochondria (succinate dehydrogenase), lysosomes (aryl sulphatase) and microsomes (NADPH cytochrome c reductase). For peroxisomal enzymes, the activities per mg of protein (specific activity) in liver homogenates were strongly correlated with the activities per g of liver and with the total activities per liver. These correlations were not obtained with crude peroxisomal fractions. Conclusions: The spectrophotometric protocols originally used to quantify the activity of mammalian peroxisomal enzymes can be successfully applied to the study of those enzymes in brown trout. Because the activity of all studied peroxisomal enzymes rose in a linear mode with temperature, their activities can be correctly measured between 10° and 37°C. Probably due to contamination by other organelles and losses of soluble matrix enzymes during homogenisation, enzyme activities in crude peroxisomal fractions do not correlate with the activities in liver homogenates. Thus, total homogenates will be used in future seasonal and toxicological studies of brown trout peroxisomes.

Microscopy and Microanalysis, 2009

The large macro- and microscopic variability in kidney morphology among fish makes it difficult t... more The large macro- and microscopic variability in kidney morphology among fish makes it difficult to build a “universal” understanding on its function and structure. Species-specific studies are thus needed. Thus, morphological study of brown trout trunk kidney was performed, considering potential seasonal and gender effects.

Microbiology and Immunology, 2011

PNAG is a major component of Staphylococcus epidermidis biofilms involved in intercellular adhesi... more PNAG is a major component of Staphylococcus epidermidis biofilms involved in intercellular adhesion as well as in the interaction of the biofilm with components of the host immune response. Synthesis of PNAG has been found to be regulated by several environmental factors. In the present study, the effect of glucose metabolism-dependent culture medium acidification in PNAG accumulation was evaluated. Established S. epidermidis biofilms were allowed to grow in excess glucose with or without maintained pH conditions. PNAG accumulation in these biofilms was determined by flow cytometry and fluorescence microscopy using wheat germ agglutinin as a fluorescent probe. Biofilms grown in maintained pH conditions presented significantly higher amounts of this polymer as well as higher icaA expression than biofilms grown in acidic pH conditions. Moreover, PNAG accumulation in biofilms grown in non-maintained pH conditions occurred in association with cell death. Overall, we show that glucose metabolism by decreasing the culture pH affects biofilm physiology in respect to PNAG production and cell death. The reported in vitro modulation of PNAG accumulation within S. epidermidis biofilms further highlights the role of environment on determining the biofilm physiological state.

Marine Drugs, 2010

Neurotoxicity induced in fish by domoic acid (DA) was assessed with respect to occurrence of neur... more Neurotoxicity induced in fish by domoic acid (DA) was assessed with respect to occurrence of neurotoxic signs, lethality, and histopathology by light microscopy. Sparus aurata were exposed to a single dose of DA by intraperitoneal (i.p.) injection of 0, 0.45, 0.9, and 9.0 mg DA kg −1 bw. Mortality (66.67 ± 16.67%) was only observed in dose of 9.0 mg kg −1 bw. Signs of neurological toxicity were detected for the doses of 0.9 and 9.0 mg DA kg −1 bw. Furthermore, the mean concentrations (±SD) of DA detected by HPLC-UV in extracts of brain after exposure to 9.0 mg DA kg −1 bw were 0.61 ± 0.01, 0.96 ± 0.00, and 0.36 ± 0.01 mg DA kg −1 tissue at 1, 2, and 4 hours. The lack of major permanent brain damage in S. aurata, and reversibility of neurotoxic signs, suggest that lower susceptibility to DA or neuronal recovery occurs in affected individuals.

International Journal of Systematic and Evolutionary Microbiology, 2011

A Gram-positive, aerobic, non-motile, endospore-forming rod, designated DS22T, was isolated from ... more A Gram-positive, aerobic, non-motile, endospore-forming rod, designated DS22T, was isolated from a drinking-water treatment plant. Cells were catalase- and oxidase-positive. Growth occurred at 15–37 °C, at pH 7–10 and with <8 % (w/v) NaCl (optimum growth: 30 °C, pH 7–8 and 1–3 % NaCl). The major respiratory quinone was menaquinone 7, the G+C content of the genomic DNA was 36.5 mol% and the cell wall contained meso-diaminopimelic acid. On the basis of 16S rRNA gene sequence analysis, strain DS22T was a member of the genus Bacillus. Its closest phylogenetic neighbours were Bacillus horneckiae NRRL B-59162T (98.5 % 16S rRNA gene sequence similarity), Bacillus oceanisediminis H2T (97.9 %), Bacillus infantis SMC 4352-1T (97.4 %), Bacillus firmus IAM 12464T (96.8 %) and Bacillus muralis LMG 20238T (96.8 %). DNA–DNA hybridization, and biochemical and physiological characterization allowed the differentiation of strain DS22T from its closest phylogenetic neighbours. The data supports the...

International Journal of Systematic and Evolutionary Microbiology, 2015

An aerobic, Gram-stain-negative rod, designated strain A2P5T, was isolated from the Douro river, ... more An aerobic, Gram-stain-negative rod, designated strain A2P5T, was isolated from the Douro river, in Porto, Portugal. Cells were catalase- and oxidase-positive. Growth occurred at 15–30 °C, at pH 6–8 and in the presence of 1 % (w/v) NaCl. The major respiratory quinone was Q8, the genomic DNA had a G+C content of 47 ± 1 mol%, and phosphatidylethanolamine, phosphatidylglycerol and diphosphatidylglycerol were amongst the major polar lipids. On the basis of 16S rRNA gene sequence analysis, strain A2P5T was observed to be a member of the family Burkholderiaceae, but could not be identified as a member of any validly named genus. The low levels of 16S rRNA gene sequence similarity to other recognized taxa ( < 91 %), together with the comparative analysis of phenotypic and chemotaxonomic characteristics, supported the proposal of a novel species of a new genus within the family Burkholderiaceae. The name Hydromonas duriensis gen. nov., sp. nov. is proposed. The type strain of Hydromonas ...

Marine Drugs, 2010

Neurotoxicity induced in fish by domoic acid (DA) was assessed with respect to occurrence of neur... more Neurotoxicity induced in fish by domoic acid (DA) was assessed with respect to occurrence of neurotoxic signs, lethality, and histopathology by light microscopy. Sparus aurata were exposed to a single dose of DA by intraperitoneal (i.p.) injection of 0, 0.45, 0.9, and 9.0 mg DA kg −1 bw. Mortality (66.67 ± 16.67%) was only observed in dose of 9.0 mg kg −1 bw. Signs of neurological toxicity were detected for the doses of 0.9 and 9.0 mg DA kg −1 bw. Furthermore, the mean concentrations (±SD) of DA detected by HPLC-UV in extracts of brain after exposure to 9.0 mg DA kg −1 bw were 0.61 ± 0.01, 0.96 ± 0.00, and 0.36 ± 0.01 mg DA kg −1 tissue at 1, 2, and 4 hours. The lack of major permanent brain damage in S. aurata, and reversibility of neurotoxic signs, suggest that lower susceptibility to DA or neuronal recovery occurs in affected individuals.