Analysis ofBrevundimonas subvibrioidesdevelopmental signaling systems reveals unexpected differences between phenotypes and c-di-GMP levels

The DivJ-DivK-PleC signaling system ofCaulobacter crescentusis a signaling network that regulates polar development and the cell cycle. This system is conserved in related bacteria, including the sister genusBrevundimonas. Previous studies had shown unexpected phenotypic differences between theC. crescentus divKmutant and the analogous mutant ofBrevundimonas subvibrioides, but further characterization was not performed. Here, phenotypic assays analyzing motility, adhesion, and pilus production (the latter characterized by a newly discovered bacteriophage) revealed thatdivJandpleCmutants have mostly similar phenotypes as theirC. crescentushomologs, butdivKmutants maintain largely opposite phenotypes than expected. Suppressor mutations of theB. subvibrioides divKmotility defect were involved in cyclic-di-GMP (c-di-GMP) signaling, including the diguanylate cyclasedgcB, andcleDwhich is hypothesized to affect flagellar function in a c-di-GMP dependent fashion. However, the screen did not identify the diguanylate cyclasepleD.Disruption ofpleDinB. subvibrioidescaused hypermotility in wild-type, but not in thedivKbackground. Analysis of c-di-GMP levels in these strains revealed incongruities between c-di-GMP levels and displayed phenotypes with a notable result that suppressor mutations altered phenotypes but had little impact on c-di-GMP levels in thedivKbackground. Conversely, when c-di-GMP levels were artificially manipulated, alterations of c-di-GMP levels in thedivKstrain had minimal impact on phenotypes. These results suggest that DivK performs a critical function in the integration of c-di-GMP signaling into theB. subvibrioidescell cycle.ImportanceCyclic-di-GMP signaling is one of the most broadly conserved signaling systems in bacteria, but there is little understanding of how this system directly affects the physiology of the organism. InC. crescentus, c-di-GMP has been integrated into the developmental cell cycle, but there is increasing evidence that environmental factors can impact this system as well. The research presented here suggests that developmental signaling could impact physiological Processes in c-di-GMP dependent and independent ways. This hints that the integration of these signaling networks could be more complex than previously hypothesized, which could have a bearing on the larger field of c-di-GMP signaling. In addition, this work further examines how much models developed in one organism can be extrapolated to related organisms.

Regional Differentiation of The Demographic Potential in Italy and Poland

The aim of this paper is to compare the demographic potential of given Italian and Polish regions. The analysis shows that the demographic situation in Poland, unlike in Italy, is not directly related to the level of development of some regions and their geographical location. In Italy, the unfavorable demographic situation is typical of most of the less-developed southern regions, whereas in Poland it oc­curs in voivodships with different economic potential, situated in different parts of the country. This is probably the result of the current polycentric development of Poland, characteristic of a centralized economy, and the polar development in Italy. Certain demographic similarities, but of different levels, related to the dynamics of the population, the level of fertility, and net migration are observable in the macro-regions of Mezzogiorno and Eastern Poland.

Kajian Isu Pemekaran di Kota Medan: Tinjauan Berdasarkan Kondisi Ketimpangan Wilayah

<p class="Abstract"><em>Generally, disparities between regions and inter-regions happened because of concentration, agglomeration, external factors, globalization, internal factor, grouping, critical growth or polar development, institution involvement in economic activities. Initially development in Medan concentrated in several sub districts as the center of government and trade activities. Based on long-term development plan of Medan 2006-2025, stated that development policy in Medan not notice of the regional gap. Disparities development between north and south of Medan are the problems for segregation issue at fourth sub-districts in the northern part of Medan. The purpose of this research is to analyze the gap condition in economic, social demography and the infrastructure’s service in Medan related to the emergence of segregation issue in North Medan. The analysis that used in research is descriptive statistic analysis, analysis of statistical correlation, crosstab analysis, and verification of statistic results using interview method so that at the end of the research will be generated economic, social demography and infrastructure services index for every sub-district in the Medan to know the development difference. </em><em>The result of correlation analysis shows that there was a correlation between disparity and segregation issue. Descriptive analysis produce the index for 4 sub districts in north side have the medium category while 17 sub districts in the south have a good category. Crosstab analysis shows that there is a correlation between disparities condition and the emergence of segregation issue. Crosstab analysis also shows that variable education facilities (senior high school), population density, and labor variables show the disparity condition significantly.</em></p>

Mutations in DivL and CckA Rescue a divJ Null Mutant of Caulobacter crescentus by Reducing the Activity of CtrA

ABSTRACT Polar development and cell division in Caulobacter crescentus are controlled and coordinated by multiple signal transduction proteins. divJ encodes a histidine kinase. A null mutation in divJ results in a reduced growth rate, cell filamentation, and mislocalized stalks. Suppressor analysis of divJ identified mutations in genes encoding the tyrosine kinase (divL) and the histidine kinase (cckA). The divL and cckA suppressor alleles all have single amino acid substitutions, some of which confer a temperature-sensitive phenotype, particularly in a wild-type background. Analysis of transcription levels from several positively regulated CtrA-dependent promoters reveals high expression in the divJ mutant, suggesting that DivJ normally serves to reduce CtrA activity. The divL and cckA suppressors reduce the amount of transcription from promoters positively regulated by CtrA, indicating that the mutations in divL and cckA are suppressing the defects of the divJ mutant by reducing the abnormally high level of CtrA activity. Immunoblotting showed no major perturbations in the CtrA protein level in any of these strains, suggesting that the high amount of CtrA activity seen in the divJ mutant and the reduced amount of activity in the suppressors are regulated at the level of activation and not transcription, translation, or degradation. In vivo phosphorylation assays confirmed that divJ mutants have elevated levels of CtrA phosphorylation and that this level is reduced in the suppressors with mutations in divL.

Identification of Genes Required for Synthesis of the Adhesive Holdfast in Caulobacter crescentus

ABSTRACT Adhesion to both abiotic and biotic surfaces by the gram-negative prothescate bacterium Caulobacter crescentus is mediated by a polar organelle called the “holdfast,” which enables the bacterium to form stable monolayer biofilms. The holdfast, a complex polysaccharide composed in part of N-acetylglucosamine, localizes to the tip of the stalk (a thin cylindrical extension of the cell wall and membranes). We report here the isolation of adhesion mutants with transposon insertions in an uncharacterized gene cluster involved in holdfast biogenesis (hfs) as well as in previously identified polar development genes (podJ and pleC), and the holdfast attachment genes (hfa). Clean deletions of three of the four genes in the hfs gene cluster (hfsDAB) resulted in a severe holdfast biogenesis phenotype. These mutants do not bind to surfaces or to a fluorescently labeled lectin, specific for N-acetylglucosamine. Transmission electron microscopy indicated that the hfsDAB mutants fail to synthesize a holdfast at the stalk tip. The predicted hfs gene products have significant sequence similarity to proteins necessary for exopolysaccharide export in gram-negative bacteria. HfsA has sequence similarity to GumC from Xanthomonas campestris, which is involved in exopolysaccharide export in the periplasm. HfsD has sequence similarity to Wza from Escherichia coli, an outer membrane protein involved in secretion of polysaccharide through the outer membrane. HfsB is a novel protein involved in holdfast biogenesis. These data suggest that the hfs genes play an important role in holdfast export.