Upstream CtrA-binding sites both induce and repress pilin gene expression in Caulobacter crescentus.

Pili are bacterial surface structures important for surface adhesion. In the alphaproteobacterium Caulobacter crescentus, the global regulator CtrA activates transcription of roughly 100 genes, including pilA which codes for the pilin monomer that makes up the pilus filament. While most CtrA-activated promoters have a single CtrA-binding site at the - 35 position and are induced at the early to mid-predivisional cell stage, the pilA promoter has 3 additional upstream CtrA-binding sites and it is induced at the late predivisional cell stage.

Whole genome-scale assessment of gene fitness of Novosphingobium aromaticavorans during spaceflight.

In microgravity, bacteria undergo intriguing physiological adaptations. There have been few attempts to assess global bacterial physiological responses to microgravity, with most studies only focusing on a handful of individual systems. This study assessed the fitness of each gene in the genome of the aromatic compound-degrading Alphaproteobacterium Novosphingobium aromaticavorans during growth in spaceflight.

Control of soft robots with inertial dynamics.

Soft robots promise improved safety and capability over rigid robots when deployed near humans or in complex, delicate, and dynamic environments. However, infinite degrees of freedom and the potential for highly nonlinear dynamics severely complicate their modeling and control. Analytical and machine learning methodologies have been applied to model soft robots but with constraints: quasi-static motions, quasi-linear deflections, or both.

The transcriptional regulator CtrA controls gene expression in Alphaproteobacteria phages: Evidence for a lytic deferment pathway.

Pilitropic and flagellotropic phages adsorb to bacterial pili and flagella. These phages have long been used to investigate multiple aspects of bacterial physiology, such as the cell cycle control in the Caulobacterales. Targeting cellular appendages for adsorption effectively constrains the population of infectable hosts, suggesting that phages may have developed strategies to maximize their infective yield.

The Impacts of Microgravity on Bacterial Metabolism.

The inside of a space-faring vehicle provides a set of conditions unlike anything experienced by bacteria on Earth. The low-shear, diffusion-limited microenvironment with accompanying high levels of ionizing radiation create high stress in bacterial cells, and results in many physiological adaptations. This review gives an overview of the effect spaceflight in general, and real or simulated microgravity in particular, has on primary and secondary metabolism.

The Use of TnSeq to Identify Essential Alphaproteobacterial Genes Reveals Operational Variability in Conserved Developmental and Cell Cycle Systems.

A powerful method for examining genetic fitness and function on a large scale is to couple saturating transposon mutagenesis with high-throughput sequencing (TnSeq). By mapping where transposon insertions can be tolerated in a genome, it is possible to analyze the fitness of every gene in a genome simultaneously under a given growth condition. While this technique can describe genes as essential or nonessential under those growth conditions, sufficient mutagenesis and sequencing depth can provide more subtle differences in fitness.

Transcriptional rewiring of the GcrA/CcrM bacterial epigenetic regulatory system in closely related bacteria.

Transcriptional rewiring is the regulation of different target genes by orthologous regulators in different organisms. While this phenomenon has been observed, it has not been extensively studied, particularly in core regulatory systems. Several global cell cycle regulators are conserved in the Alphaproteobacteria, providing an excellent model to study this phenomenon.

Analysis of Developmental Signaling Systems Reveals Inconsistencies between Phenotypes and c-di-GMP Levels.

The DivJ-DivK-PleC signaling system of is a signaling network that regulates polar development and the cell cycle. This system is conserved in related bacteria, including the sister genus Previous studies had shown unexpected phenotypic differences between the mutant and the analogous mutant of , but further characterization was not performed. Here, phenotypic assays analyzing motility, adhesion, and pilus production (the latter characterized by a newly discovered bacteriophage) revealed that and mutants have phenotypes mostly similar to their homologs, but mutants maintain largely opposite phenotypes than expected.

Genome-scale fitness profile of Caulobacter crescentus grown in natural freshwater.

Bacterial genomes evolve in complex ecosystems and are best understood in this natural context, but replicating such conditions in the lab is challenging. We used transposon sequencing to define the fitness consequences of gene disruption in the bacterium Caulobacter crescentus grown in natural freshwater, compared with axenic growth in common laboratory media. Gene disruptions in amino-acid and nucleotide sugar biosynthesis pathways and in metabolic substrate transport machinery impaired fitness in both lake water and defined minimal medium relative to complex peptone broth.

Stalk formation of Brevundimonas and how it compares to Caulobacter crescentus.

The Caulobacter crescentus cell extension known as a stalk represents an unusual bacterial morphology. C. crescentus produces stalks under multiple nutrient conditions, but the length of the stalk is increased in response to phosphate starvation.

DNA methyltransferases and epigenetic regulation in bacteria.

Epigenetics is a change in gene expression that is heritable without a change in DNA sequence itself. This phenomenon is well studied in eukaryotes, particularly in humans for its role in cellular differentiation, X chromosome inactivation and diseases like cancer. However, comparatively little is known about epigenetic regulation in bacteria.

Essential Genes Predicted in the Genome of Rubrivivax gelatinosus.

Unlabelled: Rubrivivax gelatinosus is a betaproteobacterium with impressive metabolic diversity. It is capable of phototrophy, chemotrophy, two different mechanisms of sugar metabolism, fermentation, and H2 gas production. To identify core essential genes, R.

Identification of essential alphaproteobacterial genes reveals operational variability in conserved developmental and cell cycle systems.

The cell cycle of Caulobacter crescentus is controlled by a complex signalling network that co-ordinates events. Genome sequencing has revealed many C. crescentus cell cycle genes are conserved in other Alphaproteobacteria, but it is not clear to what extent their function is conserved.

Effect of a ctrA promoter mutation, causing a reduction in CtrA abundance, on the cell cycle and development of Caulobacter crescentus.

Background: Polar development during the alphaproteobacterium Caulobacter crescentus cell cycle is integrated to the point that individual mutations can have pleiotropic effects on the synthesis of polar organelles. Disruption of the genes encoding the histidine kinase PleC, or its localization factor PodJ, disrupts synthesis or functionality of pili, flagella and adhesive holdfast. However, the mechanism by which these mutations affect polar development is not well understood.

The scaffolding and signalling functions of a localization factor impact polar development.

In the differentiating alphaproteobacterium Caulobacter crescentus, organelle synthesis at cell poles is critical to forming different progeny after cell division. Co-ordination of polar organelle synthesis, including pili and holdfast, and flagellum ejection, is mediated in part by the scaffolding protein PodJ. At the time of cell division, PodJ undergoes regulated processing to a short form that persists at the flagellar pole of swarmer cells.

A novel effector protein modulates response regulator activity without altering phosphorylation.

Genes positively regulated by the global transcriptional response regulator CtrA are not expressed during a life cycle stage of Caulobacter crescentus when the regulator is activated by phosphorylation. Gora et al. (2010), in this issue of Molecular Cell, have discovered a novel effector protein that prevents activation but not repression by the regulator without altering its phosphorylation.

Getting in the loop: regulation of development in Caulobacter crescentus.

Caulobacter crescentus is an aquatic Gram-negative alphaproteobacterium that undergoes multiple changes in cell shape, organelle production, subcellular distribution of proteins, and intracellular signaling throughout its life cycle. Over 40 years of research has been dedicated to this organism and its developmental life cycles. Here we review a portion of many developmental processes, with particular emphasis on how multiple processes are integrated and coordinated both spatially and temporally.

Youth characteristics associated with behavioral and mental health problems during the transition to residential treatment centers: the Odyssey Project population.

This study aimed to determine what youth characteristics were associated with emotional and behavioral problems exhibited within the first three months of placement in residential treatment centers (RTCs) in a sample of youth from 20 agencies in 13 states. Two primary research questions were addressed: 1) What characteristics were associated with behavior during the transition to care? 2) Were the characteristics associated with behavior during the transition the same for boys and girls? Data were drawn from the Time 1 phase of the longitudinal national Odyssey Project dataset developed by the Child Welfare League of America. Measures included an extensive child and family characteristics (CFC) form and the Achenbach Child Behavior Checklist (CBCL).

Spatial organization of Myxococcus xanthus during fruiting body formation.

Microcinematography was used to examine fruiting body development of Myxococcus xanthus. Wild-type cells progress through three distinct phases: a quiescent phase with some motility but little aggregation (0 to 8 h), a period of vigorous motility leading to raised fruiting bodies (8 to 16 h), and a period of maturation during which sporulation is initiated (16 to 48 h). Fruiting bodies are extended vertically in a series of tiers, each involving the addition of a cell monolayer on top of the uppermost layer.

Proteins associated with the Myxococcus xanthus extracellular matrix.

Fruiting body formation of Myxococcus xanthus, like biofilm formation of many other organisms, involves the production of an extracellular matrix (ECM). While the polysaccharide component has been studied, the protein component has been largely unexplored. Proteins associated with the ECM were solubilized from purified ECM by boiling with sodium dodecyl sulfate and were identified by liquid chromatography-tandem mass spectrometry of tryptic fragments.

Mental health and behavioral problems of youth in the child welfare system: residential treatment centers compared to therapeutic foster care in the Odyssey Project population.

This is the first multisite, prospective study of behavioral and mental health disorders of youth in residential treatment centers (RTC) and therapeutic foster care (TFC), and the first study to compare the two. This study addressed two questions in a sample of 22 agencies in 13 states: (1) how prevalent were emotional and behavioral disorders in the youth admitted to RTCs and TFC?, and (2) were the youth in RTCs significantly more likely to be disturbed than youth served in TFCs? Data were drawn from the Time 1 phase of the longitudinal national "Odyssey Project" developed by the Child Welfare League of America (1995). Measures included an extensive child and family characteristics form (CFC) and the Child Behavior Checklist (CBCL).

Novel lipids in Myxococcus xanthus and their role in chemotaxis.

Organisms that colonize solid surfaces, like Myxococcus xanthus, use novel signalling systems to organize multicellular behaviour. Phosphatidylethanolamine (PE) containing the fatty acid 16:1omega5 (Delta11) elicits a chemotactic response. The phenomenon was examined by observing the effects of PE species with varying fatty acid pairings.

Sexual abuse histories of youth in child welfare residential treatment centers: analysis of the Odyssey Project population.

This multi-site examination of sexual abuse histories of youth in residential treatment centers asked, for the sample as a whole and by youth's gender: (a) How many perpetrators did each youth have? (b) What was the gender of the perpetrator? (c) What proportion of youth was abused by family members? (d) What proportion of youth was abused in a child welfare setting? And, (e) what proportion of sexually abused youth were also victims of physical abuse and/or neglect? Results revealed that males were more likely to have one perpetrator, a female perpetrator, and to have been abused in a child welfare setting and less likely be abused by a family member. Implications for refining programs and practices are discussed.

A first look at the need for enhanced support services for kinship caregivers.

This article describes findings from a series of focus groups conducted with formal kinship caregivers in Maryland. The findings reveal that kinship caregivers are committed to providing safety and stability for the children placed with them. The findings also suggest that caregiving can be a significant adjustment for many kinship caregivers and that expanded support services are needed to enhance their relationship with the child welfare agency.

Aciduric Proteobacteria isolated from pH 2.9 soil.

Acidic (pH 2.9) soil was used as an inoculum to culture heterotrophic bacteria at pH values of 3-4. Four isolates were obtained; on the basis of 16S rDNA sequence, they were shown to be members of the beta- and gamma-Proteobacteria.