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Search Results: 1 - 10 of 724918 matches for " L.M.P.K. Kirb "
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A canine model of normovolaemic acute anaemia
T.C. Spotswood,R.M. Kirberger,L.M.P.K. Kirb,F. Reyers
Onderstepoort Journal of Veterinary Research , 2010, DOI: 10.4102/ojvr.v72i2.209
Abstract: The objective was to develop a non-terminal, acute normovolaemic anaemia model in dogs that has minimal effects on patient well-being. Eleven normal Beagle dogs were used. About 20 % of the circulating blood volume was removed from the jugular vein 1-3 times per day over a 3-4 day period until a haematocrit (Ht) of 13-17 % was obtained. Normovolaemia was maintained by replacing the volume deficit of the red blood cells with Ringer's lactate and re-infusing the plasma. Full blood count and Ht were monitored twice daily. The 13-17 % Ht was reached within 3-4 days with the number of phlebotomies ranging from four to seven. The model was primarily developed to determine echocardiographic values as well as Doppler abdominal splanchnic blood flow parameters in anaemic dogs as part of a study that will compare these results to similar studies in babesiosis-induced anaemia. The model may also be useful in the evaluation of the pathophysiology of anaemia in dogs or as a model for anaemia in humans.
Neonatal administration of citalopram delays somatic maturation in rats
Deiró, T.C.B.J.;Manh?es-de-Castro, R.;Cabral-Filho, J.E.;Souza, S.L.;Freitas-Silva, S.R.;Ferreira, L.M.P.;Guedes, R.C.A.;Camara, C.R.V.;Barros, K.M.F.T.;
Brazilian Journal of Medical and Biological Research , 2004, DOI: 10.1590/S0100-879X2004001000009
Abstract: we investigated the somatic maturation of neonate rats treated during the suckling period with citalopram, a selective serotonin reuptake inhibitor. groups with 6 male neonates were randomly assigned to different treatments 24 h after birth. each litter was suckled by one of the dams until the 21st postnatal day. body weight, head axis and tail length were measured daily from the 1st to the 21st postnatal day. time of ear unfolding, auditory conduit opening, incisor eruption, and eye opening was determined. pups received 5 mg (cit5), 10 mg (cit10) or 20 mg/kg (cit20) citalopram sc, or saline (0.9% nacl, w/v, sc). compared to saline, body weight was lower (24.04%, p < 0.01) for cit10 from the 10th to the 21st day and for cit20 from the 6th to the 21st day (38.19%, p < 0.01). tail length was reduced in the cit20 group (15.48%, p < 0.001) from the 8th to the 21st day. a reduction in mediolateral head axis (10.53%, p < 0.05) was observed from the 11th to the 21st day in cit10 and from the 6th to the 21st day in cit20 (13.16%, p < 0.001). a reduction in anteroposterior head axis was also observed in the cit20 group (5.28%, p < 0.05) from the 13th to the 21st day. conversely, this axis showed accelerated growth from the 12th to the 21st day in the cit5 group (13.05%, p < 0.05). auditory conduit opening was delayed in the cit5 and cit20 groups and incisor eruption was delayed in all citalopram groups. these findings show that citalopram injected during suckling to rats induces body alterations and suggest that the activity of the serotoninergic system participates in growth mechanisms.
Directed mutagenesis affects recombination in Azospirillum brasilense nif genes
Nunes, C.P.;Passaglia, L.M.P.;Schrank, A.;Schrank, I.S.;
Genetics and Molecular Biology , 2000, DOI: 10.1590/S1415-47572000000400032
Abstract: in order to improve the gene transfer/mutagenesis system for azospirillum brasilense, gene-cartridge mutagenesis was used to replace the nifd gene with the tn5 kanamycin resistance gene. the construct was transferred to a. brasilense by electrotransformation. of the 12 colonies isolated using the suicide plasmid psup202 as vector, only four did not show vector integration into the chromosome. nevertheless, all 12 colonies were deficient in acetylene reduction, indicating an nif- phenotype. four nif- mutants were analyzed by southern blot, using six different probes spanning the nif and kmr genes and the plasmid vector. apparently, several recombination events occurred in the mutant genomes, probably caused mainly by gene disruption owing to the mutagenesis technique used: resistance gene-cartridge mutagenesis combined with electrotransformation.
Partial characterization of nif genes from the bacterium Azospirillum amazonense
Potrich, D.P.;Passaglia, L.M.P.;Schrank, I.S.;
Brazilian Journal of Medical and Biological Research , 2001, DOI: 10.1590/S0100-879X2001000900002
Abstract: azospirillum amazonense revealed genomic organization patterns of the nitrogen fixation genes similar to those of the distantly related species a. brasilense. our work suggests that a. brasilense nifhdk, nifenx, fixabc operons and nifa and glnb genes may be structurally homologous to the counterpart genes of a. amazonense. this is the first analysis revealing homology between a. brasilense nif genes and the a. amazonense genome. sequence analysis of pcr amplification products revealed similarities between the amino acid sequences of the highly conserved nifd and glnb genes of a. amazonense and related genes of a. brasilense and other bacteria. however, the a. amazonense non-coding regions (the upstream activator sequence region and the region between the nifh and nifd genes) differed from related regions of a. brasilense even in nitrogenase structural genes which are highly conserved among diazotrophic bacteria. the feasibility of the 16s ribosomal rna gene-based pcr system for specific detection of a. amazonense was shown. our results indicate that the pcr primers for 16s rdna defined in this article are highly specific to a. amazonense and can distinguish this species from a. brasilense.
Directed mutagenesis affects recombination in Azospirillum brasilense nif genes
Nunes C.P.,Passaglia L.M.P.,Schrank A.,Schrank I.S.
Genetics and Molecular Biology , 2000,
Abstract: In order to improve the gene transfer/mutagenesis system for Azospirillum brasilense, gene-cartridge mutagenesis was used to replace the nifD gene with the Tn5 kanamycin resistance gene. The construct was transferred to A. brasilense by electrotransformation. Of the 12 colonies isolated using the suicide plasmid pSUP202 as vector, only four did not show vector integration into the chromosome. Nevertheless, all 12 colonies were deficient in acetylene reduction, indicating an Nif- phenotype. Four Nif- mutants were analyzed by Southern blot, using six different probes spanning the nif and Km r genes and the plasmid vector. Apparently, several recombination events occurred in the mutant genomes, probably caused mainly by gene disruption owing to the mutagenesis technique used: resistance gene-cartridge mutagenesis combined with electrotransformation.
Partial characterization of nif genes from the bacterium Azospirillum amazonense
Potrich D.P.,Passaglia L.M.P.,Schrank I.S.
Brazilian Journal of Medical and Biological Research , 2001,
Abstract: Azospirillum amazonense revealed genomic organization patterns of the nitrogen fixation genes similar to those of the distantly related species A. brasilense. Our work suggests that A. brasilense nifHDK, nifENX, fixABC operons and nifA and glnB genes may be structurally homologous to the counterpart genes of A. amazonense. This is the first analysis revealing homology between A. brasilense nif genes and the A. amazonense genome. Sequence analysis of PCR amplification products revealed similarities between the amino acid sequences of the highly conserved nifD and glnB genes of A. amazonense and related genes of A. brasilense and other bacteria. However, the A. amazonense non-coding regions (the upstream activator sequence region and the region between the nifH and nifD genes) differed from related regions of A. brasilense even in nitrogenase structural genes which are highly conserved among diazotrophic bacteria. The feasibility of the 16S ribosomal RNA gene-based PCR system for specific detection of A. amazonense was shown. Our results indicate that the PCR primers for 16S rDNA defined in this article are highly specific to A. amazonense and can distinguish this species from A. brasilense.
Purification and binding analysis of the nitrogen fixation regulatory NifA protein from Azospirillum brasilense
Passaglia, L.M.P.;Van Soom, C.;Schrank, A.;Schrank, I.S.;
Brazilian Journal of Medical and Biological Research , 1998, DOI: 10.1590/S0100-879X1998001100001
Abstract: nifa protein activates transcription of nitrogen fixation operons by the alternative s54 holoenzyme form of rna polymerase. this protein binds to a well-defined upstream activator sequence (uas) located at the -200/-100 position of nif promoters with the consensus motif tgt-n10-aca. nifa of azospirillum brasilense was purified in the form of a glutathione-s-transferase (gst)-nifa fusion protein and proteolytic release of gst yielded inactive and partially soluble nifa. however, the purified nifa was able to induce the production of specific anti-a. brasilense nifa-antiserum that recognized nifa from a. brasilense but not from k. pneumoniae. both gst-nifa and nifa expressed from the e. coli tac promoter are able to activate transcription from the nifhdk promoter but only in an a. brasilense background. in order to investigate the mechanism that regulates nifa binding capacity we have used e. coli total protein extracts expressing a. brasilense nifa in mobility shift assays. dna fragments carrying the two overlapping, wild-type or mutated uas motifs present in the nifh promoter region revealed a retarded band of related size. these data show that the binding activity present in the c-terminal domain of a. brasilense nifa protein is still functional even in the presence of oxygen.
Purification and binding analysis of the nitrogen fixation regulatory NifA protein from Azospirillum brasilense
Passaglia L.M.P.,Van Soom C.,Schrank A.,Schrank I.S.
Brazilian Journal of Medical and Biological Research , 1998,
Abstract: NifA protein activates transcription of nitrogen fixation operons by the alternative sigma54 holoenzyme form of RNA polymerase. This protein binds to a well-defined upstream activator sequence (UAS) located at the -200/-100 position of nif promoters with the consensus motif TGT-N10-ACA. NifA of Azospirillum brasilense was purified in the form of a glutathione-S-transferase (GST)-NifA fusion protein and proteolytic release of GST yielded inactive and partially soluble NifA. However, the purified NifA was able to induce the production of specific anti-A. brasilense NifA-antiserum that recognized NifA from A. brasilense but not from K. pneumoniae. Both GST-NifA and NifA expressed from the E. coli tac promoter are able to activate transcription from the nifHDK promoter but only in an A. brasilense background. In order to investigate the mechanism that regulates NifA binding capacity we have used E. coli total protein extracts expressing A. brasilense nifA in mobility shift assays. DNA fragments carrying the two overlapping, wild-type or mutated UAS motifs present in the nifH promoter region revealed a retarded band of related size. These data show that the binding activity present in the C-terminal domain of A. brasilense NifA protein is still functional even in the presence of oxygen.
Sequencing and promoter analysis of the nifENXorf3orf5fdxAnifQ operon from Azospirillum brasilense Sp7
Potrich, D.P.;Bressel, T.A.;Schrank, I.S.;Passaglia, L.M.P.;
Brazilian Journal of Medical and Biological Research , 2001, DOI: 10.1590/S0100-879X2001001100003
Abstract: a 40-kb dna region containing the major cluster of nif genes has been isolated from the azospirillum brasilense sp7 genome. in this region three nif operons have been identified: nifhdkorf1y, nifenxorf3orf5fdxanifq and orf2nifusvorf4. the operons containing nifenx and nifusv genes are separated from the structural nifhdkorf1y operon by about 5 kb and 10 kb, respectively. the present study shows the sequence analysis of the 6045-bp dna region containing the nifenx genes. the deduced amino acid sequences from the open reading frames were compared to the nif gene products of other diazotrophic bacteria and indicate the presence of seven orfs, all reading in the same direction as that of the nifhdkorf1y operon. consensus s54 and nifa-binding sites are present only in the promoter region upstream of the nife gene. this promoter is activated by nifa protein and is approximately two-times less active than the nifh promoter, as indicated by the ?-galactosidase assays. this result suggests the differential expression of the nif genes and their respective products in azospirillum.
Sequencing and promoter analysis of the nifENXorf3orf5fdxAnifQ operon from Azospirillum brasilense Sp7
Potrich D.P.,Bressel T.A.,Schrank I.S.,Passaglia L.M.P.
Brazilian Journal of Medical and Biological Research , 2001,
Abstract: A 40-kb DNA region containing the major cluster of nif genes has been isolated from the Azospirillum brasilense Sp7 genome. In this region three nif operons have been identified: nifHDKorf1Y, nifENXorf3orf5fdxAnifQ and orf2nifUSVorf4. The operons containing nifENX and nifUSV genes are separated from the structural nifHDKorf1Y operon by about 5 kb and 10 kb, respectively. The present study shows the sequence analysis of the 6045-bp DNA region containing the nifENX genes. The deduced amino acid sequences from the open reading frames were compared to the nif gene products of other diazotrophic bacteria and indicate the presence of seven ORFs, all reading in the same direction as that of the nifHDKorf1Y operon. Consensus sigma54 and NifA-binding sites are present only in the promoter region upstream of the nifE gene. This promoter is activated by NifA protein and is approximately two-times less active than the nifH promoter, as indicated by the -galactosidase assays. This result suggests the differential expression of the nif genes and their respective products in Azospirillum.
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