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Donald F Niven - One of the best experts on this subject based on the ideXlab platform.
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Acquisition of haemoglobin-bound iron by Histophilus somni.
Veterinary Microbiology, 2006Co-Authors: Yannick D N Tremblay, Fariborz Bahrami, Donald F NivenAbstract:Histophilus somni is an important pathogen of cattle and sheep. H. somni requires iron and can use ruminant transferrins as iron sources for growth. Here, we investigated the abilities of bOvine (strains 649 and 2336) and Ovine (strains 9L and 3384Y) isolates of H. somni to acquire iron from haemoglobins. Using growth assays, the bOvine isolates were shown to acquire iron from bOvine haemoglobin, but not from Ovine, porcine or human haemoglobins; the Ovine isolates, however, failed to use any of these haemoglobins as iron sources for growth. In solid phase binding assays, the bOvine isolates, grown under iron-restricted conditions in the presence of bOvine haemoglobin, bound not only bOvine but also Ovine and human haemoglobins. Competition binding assays indicated that all three haemoglobins were bound by the same receptor(s) and SDS-PAGE of membrane fractions revealed that expression of haemoglobin-binding activity was associated with the production of an ∼120-kDa outer membrane protein. PCR approaches allowed the amplification and sequencing of hgbA, and also hugX and hugZ homologues from strains 649, 9L and 3384Y. While hgbA of strain 649 was predicted to encode an HgbA precursor that is processed to yield a mature, 123.9-kDa haemoglobin-binding protein, the hgbA genes of strains 9L and 3384Y were predicted to give rise to truncated products. RT-PCR experiments revealed that in strain 649, hugX, hugZ and hgbA are co-transcribed and iron-regulated and additional sequencing suggested that in strain 2336, expression of HgbA is subject to phase variation involving a poly C tract within hgbA.
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haemophilus somnus possesses two systems for acquisition of transferrin bound iron
Journal of Bacteriology, 2004Co-Authors: Andrew Ekins, Fariborz Bahrami, Ada Sijercic, Deborah Maret, Donald F NivenAbstract:Haemophilus somnus strain 649 was found to acquire iron from Ovine, bOvine, and goat transferrins (Tfs). Expression of Tf receptors, as evaluated by solid-phase binding assays, required the organisms to be grown under iron-restricted conditions in the presence of Tf. Competition binding assays revealed the presence of two distinct Tf-binding receptor systems, one specific for bOvine Tf and the other capable of binding all three ruminant Tfs. Affinity isolation procedures using total membranes yielded three putative bOvine Tf-binding polypeptides and one putative Ovine and goat Tf-binding polypeptide. PCR amplification followed by DNA sequence analyses revealed that H. somnus strain 649 possesses genes that encode a bipartite TbpA-TbpB receptor along with a homolog of the Histophilus ovis single-component TbpA receptor. Expression of TbpB and the single-component TbpA would appear to be subject to a form of phase variation involving homopolymeric nucleotide tracts within the structural genes.
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Production of transferrin receptors by Histophilus ovis: three of five strains require two signals.
Canadian journal of microbiology, 2001Co-Authors: Andrew Ekins, Donald F NivenAbstract:Five strains of Histophilus ovis (9L, 642A, 714, 5688T, and 3384Y) were investigated with respect to iron acquisition. All strains used Ovine, bOvine, and goat transferrins (Tfs), but not porcine or human Tfs, as iron sources for growth. In solid phase binding assays, total membranes from only two (9L and 642A) of the five strains, grown under iron-restricted conditions, were able to bind Tfs (Ovine, bOvine, and goat, but not porcine or human). However, when the organisms were grown under iron-restricted conditions in the presence of bOvine transferrin (Tf), total membranes from all strains exhibited Tf binding (as above); competition experiments demonstrated that all three Tfs (Ovine, bOvine, and goat) were bound by the same receptor(s). Membranes from organisms grown under iron-replete conditions in the presence or absence of bOvine Tf failed to bind any of the test Tfs. An affinity-isolation procedure allowed the isolation of two putative Tf-binding polypeptides (78 and 66 kDa) from total membranes of ...
Isabel M P L V O Ferreira - One of the best experts on this subject based on the ideXlab platform.
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detection and quantification of bOvine Ovine and caprine milk percentages in protected denomination of origin cheeses by reversed phase high performance liquid chromatography of beta lactoglobulins
Journal of Chromatography A, 2003Co-Authors: Isabel M P L V O Ferreira, Helena CacoteAbstract:Abstract A method for detecting and quantifying bOvine, Ovine and caprine milk mixtures in milk and cheeses by means of reversed-phase high-performance liquid chromatography (RP-HPLC) of β-lactoglobulins is described. Gradient elution was carried out with a flow rate of 0.5 ml/min and a temperature of 45 °C, using a mixture of two solvents: solvent A (0.1% TFA in water) and solvent B (0.09% TFA in 80% aqueous acetonitrile, v/v). The effluent was monitored at 215 nm. Under the conditions used different chromatographic patterns were obtained for bOvine, Ovine and caprine whey proteins. Each milk type presented different retention times for β-lactoglobulin peaks. Binary mixtures of bOvine and Ovine or bOvine and caprine raw milks containing 1, 2, 5, 10, 20, 30, 50, 75 and 95% (v/v) of bOvine milk, as well as Ovine and caprine milk mixtures containing 1, 2, 5, 10, 20, 30, 50, 75 and 95% (v/v) of Ovine milk were used for cheese making. Cheeses were prepared and ripened, according to traditional methods. Milk mixtures, fresh and ripened cheeses were analyzed. A linear relationship was established between log 10 of β-lactoglobulin peaks ratio (calculated as peak area values ratio) and log 10 of the relative percentage of bOvine or Ovine milk. The ratio between β-lactoglobulin peaks was not affected by the degree of ripening. Thus, enabling the quantification of milk type percentage, with a detection limit of 2%. This technique allowed quantification of milk species within the concentration range of 5–95%. The method was successfully applied for authenticity evaluation and quantitative determination of Ovine and caprine milk percentages of commercial protected denomination of origin (PDO) cheeses.
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Detection and quantification of bOvine, Ovine and caprine milk percentages in protected denomination of origin cheeses by reversed-phase high-performance liquid chromatography of beta-lactoglobulins.
Journal of chromatography. A, 2003Co-Authors: Isabel M P L V O Ferreira, Helena CacoteAbstract:A method for detecting and quantifying bOvine, Ovine and caprine milk mixtures in milk and cheeses by means of reversed-phase high-performance liquid chromatography (RP-HPLC) of beta-lactoglobulins is described. Gradient elution was carried out with a flow rate of 0.5 ml/min and a temperature of 45 degrees C, using a mixture of two solvents: solvent A (0.1% TFA in water) and solvent B (0.09% TFA in 80% aqueous acetonitrile, v/v). The effluent was monitored at 215 nm. Under the conditions used different chromatographic patterns were obtained for bOvine, Ovine and caprine whey proteins. Each milk type presented different retention times for beta-lactoglobulin peaks. Binary mixtures of bOvine and Ovine or bOvine and caprine raw milks containing 1, 2, 5, 10, 20, 30, 50, 75 and 95% (v/v) of bOvine milk, as well as Ovine and caprine milk mixtures containing 1, 2, 5, 10, 20, 30, 50, 75 and 95% (v/v) of Ovine milk were used for cheese making. Cheeses were prepared and ripened, according to traditional methods. Milk mixtures, fresh and ripened cheeses were analyzed. A linear relationship was established between log 10 of beta-lactoglobulin peaks ratio (calculated as peak area values ratio) and log 10 of the relative percentage of bOvine or Ovine milk. The ratio between beta-lactoglobulin peaks was not affected by the degree of ripening. Thus, enabling the quantification of milk type percentage, with a detection limit of 2%. This technique allowed quantification of milk species within the concentration range of 5-95%. The method was successfully applied for authenticity evaluation and quantitative determination of Ovine and caprine milk percentages of commercial protected denomination of origin (PDO) cheeses.
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separation and quantification of the major casein fractions by reverse phase high performance liquid chromatography and urea polyacrylamide gel electrophoresis detection of milk adulterations
Journal of Chromatography A, 2002Co-Authors: Ana C A Veloso, Natercia Teixeira, Isabel M P L V O FerreiraAbstract:The separation and quantification of bOvine kappa-, alpha- and beta-caseins by HPLC-UV using an RP column which contained polystyrene-divinilbenzene copolymer based packing was optimized and validated. Gradient elution was carried out at a flow-rate of 1 ml/min and a temperature of 46 degrees C, using a mixture of two solvents. Solvent A was 0.1% trifluoroacetic acid in water and solvent B was acetonitrile-water-trifluoroacetic acid (95:5:0.1). The effluent was monitored by a UV detector at 280 nm. The determinations were performed in the linear range of 0.038-0.377 mg/ml for kappa-casein, 0.188-1.883 mg/ml for alpha-casein and 0.151-1.506 mg/ml for beta-casein. The detection limits were 0.006, 0.019 and 0.015 mg/ml for kappa-casein, alpha-casein and beta-casein, respectively. The validity of the method was verified. The recoveries ranged from 91 to 100% for bOvine milk. The precision of the method was also evaluated, the RSD being less than 3.67%. The same HPLC procedure was used for the separation of caprine and Ovine caseins. Different chromatographic profiles were obtained for bOvine, Ovine and caprine milks, although it was only possible to detect and quantify additions of 5% or more of bOvine milk to caprine milk. With respect to detection of milk adulterations, electrophoresis using urea-polyacrylamide gel electrophoresis (PAGE) analysis was more sensitive. The evolution of casein proteolysis in cheeses made from bOvine milk and cheeses made from Ovine milk, during 30 days of ripening was followed by HPLC-UV and urea-PAGE methodologies. The results obtained by these techniques were similar.
Helena Cacote - One of the best experts on this subject based on the ideXlab platform.
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detection and quantification of bOvine Ovine and caprine milk percentages in protected denomination of origin cheeses by reversed phase high performance liquid chromatography of beta lactoglobulins
Journal of Chromatography A, 2003Co-Authors: Isabel M P L V O Ferreira, Helena CacoteAbstract:Abstract A method for detecting and quantifying bOvine, Ovine and caprine milk mixtures in milk and cheeses by means of reversed-phase high-performance liquid chromatography (RP-HPLC) of β-lactoglobulins is described. Gradient elution was carried out with a flow rate of 0.5 ml/min and a temperature of 45 °C, using a mixture of two solvents: solvent A (0.1% TFA in water) and solvent B (0.09% TFA in 80% aqueous acetonitrile, v/v). The effluent was monitored at 215 nm. Under the conditions used different chromatographic patterns were obtained for bOvine, Ovine and caprine whey proteins. Each milk type presented different retention times for β-lactoglobulin peaks. Binary mixtures of bOvine and Ovine or bOvine and caprine raw milks containing 1, 2, 5, 10, 20, 30, 50, 75 and 95% (v/v) of bOvine milk, as well as Ovine and caprine milk mixtures containing 1, 2, 5, 10, 20, 30, 50, 75 and 95% (v/v) of Ovine milk were used for cheese making. Cheeses were prepared and ripened, according to traditional methods. Milk mixtures, fresh and ripened cheeses were analyzed. A linear relationship was established between log 10 of β-lactoglobulin peaks ratio (calculated as peak area values ratio) and log 10 of the relative percentage of bOvine or Ovine milk. The ratio between β-lactoglobulin peaks was not affected by the degree of ripening. Thus, enabling the quantification of milk type percentage, with a detection limit of 2%. This technique allowed quantification of milk species within the concentration range of 5–95%. The method was successfully applied for authenticity evaluation and quantitative determination of Ovine and caprine milk percentages of commercial protected denomination of origin (PDO) cheeses.
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Detection and quantification of bOvine, Ovine and caprine milk percentages in protected denomination of origin cheeses by reversed-phase high-performance liquid chromatography of beta-lactoglobulins.
Journal of chromatography. A, 2003Co-Authors: Isabel M P L V O Ferreira, Helena CacoteAbstract:A method for detecting and quantifying bOvine, Ovine and caprine milk mixtures in milk and cheeses by means of reversed-phase high-performance liquid chromatography (RP-HPLC) of beta-lactoglobulins is described. Gradient elution was carried out with a flow rate of 0.5 ml/min and a temperature of 45 degrees C, using a mixture of two solvents: solvent A (0.1% TFA in water) and solvent B (0.09% TFA in 80% aqueous acetonitrile, v/v). The effluent was monitored at 215 nm. Under the conditions used different chromatographic patterns were obtained for bOvine, Ovine and caprine whey proteins. Each milk type presented different retention times for beta-lactoglobulin peaks. Binary mixtures of bOvine and Ovine or bOvine and caprine raw milks containing 1, 2, 5, 10, 20, 30, 50, 75 and 95% (v/v) of bOvine milk, as well as Ovine and caprine milk mixtures containing 1, 2, 5, 10, 20, 30, 50, 75 and 95% (v/v) of Ovine milk were used for cheese making. Cheeses were prepared and ripened, according to traditional methods. Milk mixtures, fresh and ripened cheeses were analyzed. A linear relationship was established between log 10 of beta-lactoglobulin peaks ratio (calculated as peak area values ratio) and log 10 of the relative percentage of bOvine or Ovine milk. The ratio between beta-lactoglobulin peaks was not affected by the degree of ripening. Thus, enabling the quantification of milk type percentage, with a detection limit of 2%. This technique allowed quantification of milk species within the concentration range of 5-95%. The method was successfully applied for authenticity evaluation and quantitative determination of Ovine and caprine milk percentages of commercial protected denomination of origin (PDO) cheeses.
Manuel Nuñez - One of the best experts on this subject based on the ideXlab platform.
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microbiological chemical and sensory characteristics of hispanico cheese manufactured using frozen high pressure treated curds made from raw Ovine milk
International Dairy Journal, 2011Co-Authors: Rocio Alonso, Pilar Gaya, Antonia Picon, Estrella Fernandezgarcia, Buenaventura Rodriguez, Manuel NuñezAbstract:A novel procedure to overcome the seasonal shortage of Ovine milk used for cheese manufacture was investigated. Curds made from raw Ovine milk in spring months were treated at 400 or 500 MPa of pressure, and frozen for 4 months. After thawing, they were added to fresh bOvine curd made from pasteurized milk for the manufacture of experimental Hispanico cheeses. Experimental cheeses exhibited lower dry matter content, less firm texture and higher total free amino acid concentration than a control cheese made from a mixture of pasteurized bOvine and Ovine milk. Cheese obtained using curds pressurized at 400 MPa showed the highest levels of esterase activity, total free fatty acids, 2-propanol, 2-butanol, 2-pentanol and ethyl hexanoate. The use of frozen pressurized curd made from raw Ovine milk for Hispanico cheese manufacture seemed not to have altered its flavour characteristics but increased the yield of the ripe cheese.
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microbiological chemical textural and sensory characteristics of hispanico cheese manufactured using frozen Ovine milk curds scalded at different temperatures
International Dairy Journal, 2010Co-Authors: Antonia Picon, Pilar Gaya, Rocio Alonso, Estrella Fernandezgarcia, Buenaventura Rodriguez, Maximo De Paz, Manuel NuñezAbstract:Abstract Hispanico cheese is a semi-hard variety, manufactured in Spain from a mixture of pasteurized bOvine and Ovine milk. To study one strategy for overcoming a seasonal shortage of Ovine milk in summer and autumn, curds made from Ovine milk, scalded at 32, 35 or 38 °C, were pressed for 30 min and frozen at −24 °C for 4 months. After thawing, they were added to fresh bOvine milk curd for the manufacture of experimental Hispanico cheeses. Control cheese was made from a mixture of pasteurized bOvine and Ovine milk in the same (80:20) proportion. No significant effect of the addition of frozen Ovine milk curd or scalding temperature was found for lactic acid bacteria counts, dry matter content, hydrophilic and hydrophobic peptides, 45 out of 65 volatile compounds, texture, and sensory characteristics throughout a 60-day ripening period. Differences between cheeses, of low magnitude and little practical significance, were found for pH value, aminopeptidase activity, proteolysis, free amino acids, free fatty acids, and the remaining 20 volatile compounds. Thus, the addition of frozen Ovine milk curd to fresh bOvine milk curd does not alter the main physicochemical and sensory characteristics of Hispanico cheese.
Kwok-yung Yuen - One of the best experts on this subject based on the ideXlab platform.
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Discovery and Genomic Characterization of a Novel Ovine Partetravirus and a New Genotype of BOvine Partetravirus
PloS one, 2011Co-Authors: Herman Tse, Hoi-wah Tsoi, Jade L. L. Teng, Xinchun Chen, Haiying Liu, Boping Zhou, Bo-jian Zheng, Patrick C. Y. Woo, Susanna K. P. Lau, Kwok-yung YuenAbstract:Partetravirus is a recently described group of animal parvoviruses which include the human partetravirus, bOvine partetravirus and porcine partetravirus (previously known as human parvovirus 4, bOvine hokovirus and porcine hokovirus respectively). In this report, we describe the discovery and genomic characterization of partetraviruses in bOvine and Ovine samples from China. These partetraviruses were detected by PCR in 1.8% of bOvine liver samples, 66.7% of Ovine liver samples and 71.4% of Ovine spleen samples. One of the bOvine partetraviruses detected in the present samples is phylogenetically distinct from previously reported bOvine partetraviruses and likely represents a novel genotype. The Ovine partetravirus is a novel partetravirus and phylogenetically most related to the bOvine partetraviruses. The genome organization is conserved amongst these viruses, including the presence of a putative transmembrane protein encoded by an overlapping reading frame in ORF2. Results from the present study provide further support to the classification of partetraviruses as a separate genus in Parvovirinae.
