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Selected AbstractsRegulation of anaerobic arginine catabolism in Bacillus licheniformis by a protein of the Crp/Fnr familyFEMS MICROBIOLOGY LETTERS, Issue 2 2000Abdelouahid Maghnouj Abstract Arginine anaerobic catabolism occurs in Bacillus licheniformis through the arginine deiminase pathway, encoded by the gene cluster arcABDC. We report here the involvement of a new protein, ArcR, in the regulation of the pathway. ArcR is a protein of the Crp/Fnr family encoded by a gene located 109 bp downstream from arcC. It binds to a palindromic sequence, very similar to an Escherichia coli Crp binding site, located upstream from arcA. Residues in the C-terminal domain of Crp that form the DNA binding motif, in particular residues Arg-180 and Glu-181 that make specific bonds with DNA, are conserved in ArcR, suggesting that the complexes formed with DNA by Crp and ArcR are similar. Moreover, the pattern of DNase I hypersensitivity sites induced by the binding of ArcR suggests that ArcR bends the DNA in the same way as Crp. From the absence of anaerobic induction following inactivation of arcR and from the existence of a binding site upstream of the arcA transcription start point, it can be inferred that ArcR is an activator of the arginine deiminase pathway. [source] Long-term precipitation and slide activity in south-eastern Norway, autumn 2000HYDROLOGICAL PROCESSES, Issue 4 2008Christian Jaedicke Abstract In autumn 2000 high amounts of precipitation caused a large number of landslides in south-eastern Norway. The precipitation reached more than 400% of the normal monthly values in November. In addition to the precipitation, groundwater monitoring showed unusual high levels. High air temperatures in the mountains caused the precipitation to fall as rain instead of snow, causing additional runoff in the catchments. In this paper, 90 landslides are presented that were studied and evaluated by the Norwegian Geotechnical Institute (NGI) in the counties effected by the slide activity. The landslide database serves as start point for an analysis of the connection between slide activity and precipitation. The analysis shows a high variability of the observed precipitation just a few days before the slides. This variability decreases significantly around 50 days prior to the slides when the results stabilize at about 400% of normal precipitation in a 50-day period. Comparison of these results to long time observations gives an estimate of return periods for the precipitation events. The 53 days accumulated precipitation has the highest return period of 132 years. This suggests that the high landslide activity in autumn 2000 in south-eastern Norway was caused by a long-term infiltration of large amounts of precipitation rather than high rainfall intensities during a short period. Copyright © 2007 John Wiley & Sons, Ltd. [source] On-line estimation and path planning for multiple vehicles in an uncertain environmentINTERNATIONAL JOURNAL OF ROBUST AND NONLINEAR CONTROL, Issue 8 2004Jarurat Ousingsawat Abstract A unified approach to cooperative target tracking and path planning for multiple vehicles is presented. All vehicles, friendly and adversarial, are assumed to be aircraft. Unlike the typical target tracking problem that uses the linear state and nonlinear output dynamics, a set of aircraft nonlinear dynamics is used in this work. Target state information is estimated in order to integrate into a path planning framework. The objective is to fly from a start point to a goal in a highly dynamic, uncertain environment with multiple friendly and adversarial vehicles, without collision. The estimation architecture proposed is consistent with most path planning methods. Here, the path planning approach is based on evolutionary computation technique which is then combined with a nonlinear extended set membership filter in order to demonstrate a unified approach. A cooperative estimation approach among friendly vehicles is shown to improve speed and routing of the path. Copyright © 2004 John Wiley & Sons, Ltd. [source] Transcriptional analysis of the gdhA gene in Streptococcus thermophilusJOURNAL OF APPLIED MICROBIOLOGY, Issue 4 2009C. Lazzi Abstract Aims:, To study the transcriptional analysis of glutamate dehydrogenase gene, involved in the amino acid conversion to aroma compound in Streptococcus thermophilus. Methods and Results:, Analysis of the gdhA gene nucleotide sequence of S. thermophilus CNRZ1066 revealed that the coding region is 1353 nucleotides long. The deduced amino acids sequence exhibits the putative GDH active site and some conserved domains characteristic of family I of hexameric GDHs. Phylogenetic analysis revealed that the gdh gene of S. thermophilus clustered with the orthologues of other streptococci such as Streptococcus mutans, Streptococcus agalactiae and Streptococcus infantarius. Studying the structural organization of the gdhA locus the amino acid similarity of GDHs was higher than 87%, but the locus organization was not conserved. A dominant transcript of approximately 1·4 kbp was revealed by Northern blot hybridization, suggesting that gdhA mRNA is monocystronic. Primer extension showed that transcription start point of gdhA was localized 43 bp upstream of the potential start codon (ATG). Conclusions:, The gdhA represents a monocistronic operon highly conserved in phylogenetic-related bacteria. Significance and Impact of the Study:, A deeper knowledge of gdh transcriptional mechanisms could lead to develop S. thermophilus industrial starter cultures with optimized aromatic properties. [source] Pose Optimization of Serial Manipulators Using Knowledge of Their Velocity-Degenerate (Singular) ConfigurationsJOURNAL OF FIELD ROBOTICS (FORMERLY JOURNAL OF ROBOTIC SYSTEMS), Issue 5 2003Scott B. Nokleby This work investigates the exploitation of velocity-degenerate configurations to optimize the pose of either nonredundant or redundant serial manipulators to sustain desired wrenches. An algorithm is developed that determines a desirable start point for the optimization of a serial manipulator's pose. The start-point algorithm (SPA) uses analytical expressions of the velocity-degenerate (singular) configurations of a serial manipulator to determine a pose that would be best suitable to sustain a desired wrench. Results for an example redundant serial manipulator are presented. The example results show that by using the SPA with the optimization routine, the resulting poses obtained require less effort from the actuators when compared to the poses obtained without using the SPA. It is shown that when no constraint is imposed on the position of the end-effector, the SPA excels at providing a better solution with less iterations than running the optimization without the SPA. © 2003 Wiley Periodicals, Inc. [source] amfR, an essential gene for aerial mycelium formation, is a member of the AdpA regulon in the A-factor regulatory cascade in Streptomyces griseusMOLECULAR MICROBIOLOGY, Issue 4 2003Haruka Yamazaki Summary In Streptomyces griseus, A-factor (2-isocapryloyl-3R -hydroxymethyl-,-butyrolactone) acts as a chemical signalling molecule that triggers morphological differentiation and secondary metabolism. A transcriptional activator, AdpA, in the A-factor regulatory cascade switches on a number of genes required for both processes, thus forming an AdpA regulon. amfR encoding a regulatory protein similar to response regulators of bacterial two-component regulatory systems and essential for aerial mycelium formation was found to be a member of the AdpA regulon. AdpA bound two sites at nucleotide positions approximately ,200 (site 1) and ,60 (site 2), with respect to the major transcriptional start point of amfR, and accelerated the transcription of amfR by assisting RNA polymerase in forming an open complex at an appropriate region including the transcriptional start point. Site 2 contributed more to the transcriptional activation of amfR by AdpA than site 1, although AdpA showed a much lower affinity to site 2 than to site 1. The amfR transcription enhanced by AdpA subsequently ceased at day 2 when aerial hyphae began to be formed in the wild-type strain, whereas in an adsA null mutant amfR was continuously transcribed even until day 3. This implied that amfR was repressed growth dependently by a gene product under the control of ,-AdsA. Transcription of the promoter upstream of amfT depended on amfR, which is consistent with the idea that AmfR serves as an activator for amfTSBA in the amf operon. The observations that the amfR gene contains a TTA codon, a potential target for bldA -mediated regulation, and a conserved Asp-54 residue, which might be phosphorylated by a sensor kinase, suggest that the amf operon is under transcriptional, translational and post-translational control systems. [source] The CitST two-component system regulates the expression of the Mg-citrate transporter in Bacillus subtilisMOLECULAR MICROBIOLOGY, Issue 4 2000Hiroki Yamamoto citS and citT genes encoding a new two-component system were identified in the 71° region between the pel and citM loci on the Bacillus subtilis chromosome. citS- and citT- deficient strains were unable to grow on minimal plates including citrate as a sole carbon source. In addition, a strain deficient in citM, which encodes the secondary transporter of the Mg-citrate complex, exhibited the same phenotype on this medium. Northern blot analysis revealed that citM was polycistronically transcribed with the downstream yflN gene, and that CitS and CitT were necessary for transcription of the citM,yflN operon. Upon addition of 2 mM citrate to DSM, this operon was strongly induced after the middle of the exponential growth phase in the wild type, but not in the citST double null mutant. Moreover, the transcription of this operon was completely repressed in the presence of 1% glucose. We found a sequence exhibiting homology to a catabolite-responsive element (cre) in the citM promoter region. Glucose repression was lost in ccpA and citM,cre mutants. From the result of a citM,promoter deletion experiment, putative CitT target sequences were found to be located around two regions, from ,62 to ,74 and from ,149 to ,189, relative to the citM start point. Furthermore, DNase I footprinting assays revealed that these two CitT target regions extended maximally from ,36 to ,84 and from ,168 to ,194. From these findings, we concluded that the expression of citM is positively regulated by the CitST system and negatively regulated by CcpA. [source] Effects of Gonadotropins on In Vitro Maturation and of Electrical Stimulation on Parthenogenesis of Canine OocytesREPRODUCTION IN DOMESTIC ANIMALS, Issue 1 2010BS Kim Contents The objective of this study was to determine the effects of gonadotropins on in vitro maturation (IVM) and electrical stimulation on the parthenogenesis of canine oocytes. In experiment I, cumulus oocyte complexes were collected from ovaries at a random phase of the oestrus cycle and cultured on maturation medium treated with hCG or eCG for 48 or 72 h. There were no significant differences in the effects on the metaphase II (MII) rate between the hCG and eCG treatment groups over 48 h (5.4% vs 5.5%). The MII rate in the co-treatment group of hCG and eCG for 48 h was higher than in each hormone treated group (15.5%, p < 0.05). In experiment 2, the parthenogenetic effect on oocyte development, at various electrical field strengths (1.0, 1.5, 2.0 kV/cm DC) for 60 or 80 ,s with a single DC pulse after IVM on the co-treatment of hCG and eCG, was examined. The rate of pronuclear formation (37.1%) in electrical activation at 1.5 kV/60 ,s without cytochalasin B (CB) was higher than that of oocytes activated in the other groups (p < 0.05). However, we did not observe the cleavage stages. Also, CB did not influence parthenogenesis of canine oocytes. The results showed that the pronucleus formation rate, indicative of the parthenogenesis start point, could be increased by electrical stimulation. Therefore, these results can provide important data for the parthenogenesis of canine oocytes and suggest the probability of parthenogenesis in canines. [source] An application of Routh stability criterion to derive the necessary conditions for multiplicity of a CSTRTHE CANADIAN JOURNAL OF CHEMICAL ENGINEERING, Issue 1 2009Yu-Shu Chien Abstract It is well known that the Routh stability criterion (RSC) is a powerful method for analyzing control system stability. A new RSC finding that can aid the tangent analysis method (TAM) to determine the necessary conditions for multiplicity is presented. Adding RSC to TAM can find the bifurcation start point which cannot be obtained using TAM alone. To the author's knowledge, the above new RSC application has not been discussed in past literatures. Our results are helpful for chemical reactor design. We used two examples of the binary reaction in a non-adiabatic CSTR to demonstrate the merit of our methods. Il est bien connu que le critère de stabilité de Routh (RSC) est une méthode puissante pour l'analyse de la stabilité des systèmes de contrôle. On présente un nouveau résultat de RSC pouvant aider la méthode d'analyse des tangentes (TAM) à déterminer les conditions nécessaires pour la multiplicité. L'ajout de RSC à TAM permet de trouver le point de départ de la bifurcation qui ne peut pas être obtenu uniquement avec TAM. À la connaissance de l'auteur, cette nouvelle application RSC n'a pas été examinée dans la littérature scientifique antérieure. Nos résultats sont utiles pour la conception des réacteurs chimiques. Nous utilisons deux exemples de réaction binaire dans un CSTR non adiabatique pour démontrer le mérite de nos méthodes. [source] Gene silencing of MIR22 in acute lymphoblastic leukaemia involves histone modifications independent of promoter DNA methylationBRITISH JOURNAL OF HAEMATOLOGY, Issue 1 2010Xiaoqing Li Summary Aberrant epigenetic regulation has recently been implicated in the downregulation of tumour suppressor microRNAs (miRNAs). Histone modification and DNA methylation can have different roles in gene silencing in cancer. To investigate whether histone modifications would contribute to the dysregulation of miRNAs in acute lymphoblastic leukaemia (ALL), the effect of a histone deacetylase inhibitor, trichostatin A (TSA), on miRNA expression profile was analysed by microarray assay in a precursor B-cell ALL cell line NALM-6. A total of 10 miRNAs were downregulated and 31 were upregulated significantly following TSA treatment. Among TSA-upregulated miRNAs, MIR22 is an extronic miRNA and resides in the second exon of the non-coding transcript MGC14376. Upregulation of MIR22 transcription was found in both NALM-6 cells and primary human ALL malignant cells treated with TSA. Whereas a CpG island was identified within the promoter element of MIR22, no promoter DNA methylation was detected in these cells. In contrast, accumulation of the repressive histone marker H3K27 trimethylation (H3K27triM) was indentified around the transcriptional start point of the gene, which was reduced by TSA treatment. Thus, accumulation of H3K27triM independent of promoter DNA methylation may be a novel epigenetic mechanism for MIR22 silencing in ALL. [source] Iron availability affects mcyD expression and microcystin-LR synthesis in Microcystis aeruginosa PCC7806ENVIRONMENTAL MICROBIOLOGY, Issue 10 2008Emma Sevilla Summary Microcystins are toxins produced by cyanobacteria that entail serious health and environmental problems. They are cyclic heptapeptides synthesized via a mixed polyketide synthase/non-ribosomal peptide synthetase system called microcystin synthetase. Environmental and nutritional factors that trigger microcystin synthesis are still debated and this work deals with the study of the influence of iron nutritional status on the microcystin synthesis. The results indicate that iron deficiency could be one of the inducing factors of the microcystin synthesis. For the first time, increased transcription of an essential mcy gene and correlative microcystin synthesis has been established. Real-time PCR analysis of mcyD, and microcystin-LR synthesis were studied on Microcystis aeruginosa PCC7806 grown in iron-replete and iron-deplete media. Iron starvation causes an increase of mcyD transcription, correlative to the increase of microcystin-LR levels. Four transcription start points were identified for mcyD and two for mcyA, and they are not changed as a consequence of iron deficiency. [source] | ||||||||||||||||