Differential Actions of Chlorhexidine on the Cell Wall of Bacillus subtilis and Escherichia coli

Chlorhexidine is a chlorinated phenolic disinfectant used commonly in mouthwash for its action against bacteria. However, a comparative study of the action of chlorhexidine on the cell morphology of Gram-positive and Gram-negative bacteria is lacking. In this study, the actions of chlorhexidine on the cell morphology were identified with the aids of electron microscopy. After exposure to chlorhexidine, numerous spots of indentation on the cell wall were found in both Bacillus subtilis and Escherichia coli. The number of indentation spots increased with time of incubation and increasing chlorhexidine concentration. Interestingly, the dented spots found in B. subtilis appeared mainly at the hemispherical caps of the cells, while in E. coli the dented spots were found all over the cells. After being exposed to chlorhexidine for a prolonged period, leakage of cellular contents and subsequent ghost cells were observed, especially from B subtilis. By using 2-D gel/MS-MS analysis, five proteins related to purine nucleoside interconversion and metabolism were preferentially induced in the cell wall of E. coli, while three proteins related to stress response and four others in amino acid biosynthesis were up-regulated in the cell wall materials of B. subtilis. The localized morphological damages together with the biochemical and protein analysis of the chlorhexidine-treated cells suggest that chlorhexidine may act on the differentially distributed lipids in the cell membranes/wall of B. subtilis and E. coli

Hydrodynamic modelling of protein conformation in solution: ELLIPS and HYDRO

The last three decades has seen some important advances in our ability to represent the conformation of proteins in solution on the basis of hydrodynamic measurements. Advances in theoretical modeling capabilities have been matched by commensurate advances in the precision of hydrodynamic measurements. We consider the advances in whole-body (simple ellipsoid-based) modeling—still useful for providing an overall idea of molecular shape, particularly for those systems where only a limited amount of data is available—and outline the ELLIPS suite of algorithms which facilitates the use of this approach. We then focus on bead modeling strategies, particularly the surface or shell–bead approaches and the HYDRO suite of algorithms. We demonstrate how these are providing great insights into complex issues such as the conformation of immunoglobulins and other multi-domain complexes

A Gigantic Shark from the Lower Cretaceous Duck Creek Formation of Texas

Author Contributions Conceived and designed the experiments: JAF SNS JAD-F. Analyzed the data: JAF SNS. Wrote the paper: JAF SNS. Site data for OMNH V1727 are available by request from the department of vert. paleontology at the (SN)OMNH.Three large lamniform shark vertebrae are described from the Lower Cretaceous of Texas. We interpret these fossils as belonging to a single individual with a calculated total body length of 6.3 m. This large individual compares favorably to another shark specimen from the roughly contemporaneous Kiowa Shale of Kansas. Neither specimen was recovered with associated teeth, making confident identification of the species impossible. However, both formations share a similar shark fauna, with Leptostyrax macrorhiza being the largest of the common lamniform sharks. Regardless of its actual identification, this new specimen provides further evidence that large-bodied lamniform sharks had evolved prior to the Late Cretaceous.Ye

Anxious Personality and Breast Cancer: Possible Negative Impact on Quality of Life After Breast-Conserving Therapy

Background Quality of Life (QoL) is an important outcome measure in oncology. To assess the influence of surgical treatment and personality on QoL in women with breast cancer, a longitudinal prospective cohort study was done. Methods Women (n = 222) completed questionnaires concerning QoL (WHOQOL 100) and personality (NEO-FFI and STAI) prior to the diagnosis of breast cancer and 1, 3, 6, and 12 months after diagnosis and treatment. One hundred five women were treated with breast-conserving therapy (BCT) and 117 women underwent mastectomy (MTC). Results The two treatment groups did not differ on overall QoL. At all measurement times the influence of trait anxiety on overall QoL was substantial in the BCT group. Women with a high score on trait anxiety were seven times more likely to have a low overall QoL 1 year after BCT. In the MTC group overall QoL was influenced mainly by neuroticism. Conclusions Personality, especially trait anxiety and neuroticism, determined patients' overall QoL scores. Women with an anxious personality fared worse concerning QoL after breast conserving therap

Theropod Fauna from Southern Australia Indicates High Polar Diversity and Climate-Driven Dinosaur Provinciality

The Early Cretaceous fauna of Victoria, Australia, provides unique data on the composition of high latitude southern hemisphere dinosaurs. We describe and review theropod dinosaur postcranial remains from the Aptian–Albian Otway and Strzelecki groups, based on at least 37 isolated bones, and more than 90 teeth from the Flat Rocks locality. Several specimens of medium- and large-bodied individuals (estimated up to ∼8.5 metres long) represent allosauroids. Tyrannosauroids are represented by elements indicating medium body sizes (∼3 metres long), likely including the holotype femur of Timimus hermani, and a single cervical vertebra represents a juvenile spinosaurid. Single specimens representing medium- and small-bodied theropods may be referrable to Ceratosauria, Ornithomimosauria, a basal coelurosaur, and at least three taxa within Maniraptora. Thus, nine theropod taxa may have been present. Alternatively, four distinct dorsal vertebrae indicate a minimum of four taxa. However, because most taxa are known from single bones, it is likely that small-bodied theropod diversity remains underestimated. The high abundance of allosauroids and basal coelurosaurs (including tyrannosauroids and possibly ornithomimosaurs), and the relative rarity of ceratosaurs, is strikingly dissimilar to penecontemporaneous dinosaur faunas of Africa and South America, which represent an arid, lower-latitude biome. Similarities between dinosaur faunas of Victoria and the northern continents concern the proportional representatation of higher clades, and may result from the prevailing temperate–polar climate of Australia, especially at high latitudes in Victoria, which is similar to the predominant warm–temperate climate of Laurasia, but distinct from the arid climate zone that covered extensive areas of Gondwana. Most dinosaur groups probably attained a near-cosmopolitan distribution in the Jurassic, prior to fragmentation of the Pangaean supercontinent, and some aspects of the hallmark ‘Gondwanan’ fauna of South America and Africa may therefore reflect climate-driven provinciality, not vicariant evolution driven by continental fragmentation. However, vicariance may still be detected at lower phylogenetic levels

Uptake of chlorine and loss of phosphorus by bacterial cells in 0.75

<p> <b>mg/L chlorhexidine.</b> The cellular contents of chlorine (a) and phosphorus (b) in the culture of <i>B. subtilis</i> (diamond) or <i>E. coli</i> (circle) at different time points were subjected to analysis using EDAX with an environmental scanning electron microscope (ESEM) as described in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0036659#s2" target="_blank">Materials and Methods</a>. Standard errors were calculated based on the results from three separate samples. Experiment in (b) was repeated twice and the averages of the two were plotted.</p

Maternal gut bacteria promote neurodevelopmental abnormalities in mouse offspring

Maternal immune activation (MIA) contributes to behavioral abnormalities associated with neurodevelopmental disorders in both primate and rodent offspring1-4. In humans, epidemiological studies suggest that exposure of fetuses to maternal inflammation increases the likelihood of developing Autism Spectrum Disorder (ASD)5-7. We recently demonstrated that interleukin-17a (IL-17a) produced by Th17 cells, CD4+ T helper effector cells involved in multiple inflammatory conditions, is required in pregnant mice to induce behavioral as well as cortical abnormalities in the offspring exposed to MIA8. However, it is unclear if other maternal factors are required to promote MIA-associated phenotypes. Moreover, underlying mechanisms by which MIA leads to T cell activation with increased IL-17a in the maternal circulation are not well understood. Here, we show that MIA phenotypes in offspring require maternal intestinal bacteria that promote Th17 cell differentiation. Pregnant mice that had been colonized with the mouse commensal segmented filamentous bacteria (SFB) or human commensal bacteria that induce intestinal Th17 cells were more likely to produce offspring with MIA-associated abnormalities. We also show that small intestine dendritic cells (DCs) from pregnant, but not from non-pregnant, females upon exposure to MIA secrete IL-1β/IL-23/IL-6 and stimulate T cells to produce IL-17a. Overall, our data suggest that defined gut commensal bacteria with a propensity to induce Th17 cells may increase the risk for neurodevelopmental disorders in offspring of pregnant mothers undergoing immune system activation due to infections or autoinflammatory syndromes

Effect of chlorhexidine on the growth of bacterial cells.

<p>(a) Definition of trunk and tip of a bacterial cell. The two hemispherical caps are the tips while the middle cylindrical zone is the trunk of a rod-shaped bacterial cell as described in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0036659#s2" target="_blank">Materials and methods</a>. (b and c) The growth of <i>B. subtilis</i> (b) and <i>E. coli</i> (c) was monitored by measuring the optical density of the culture. The culture was sampled at a particular time point and OD at 600 nm was measured. The concentrations of chlorhexidine added to the culture were: 0 (open rectangle), 0.25 (filled rectangle), 0.5 (closed triangle), 0.75 (closed circle) mg/L. Each plot of the curve is the average of three readings and standard deviation is shown.</p

Effect of chlorhexidine exposure on phospholipids content in <i>B. subtilis</i> and <i>E. coli</i>.

<p><i>B. subtilis</i> (diamond) and <i>E. coli</i> (circle) were treated with 0, 0.3, and 0.75 mg/L of chlorhexidine for 3 h and then subjected to EDAX to determine the contents of phosphorus and chlorine retained in the cells. The results were confirmed in two independent experiments.</p

Summary of the proteins from the cell wall fractions of CHX-treated <i>E. coli</i> and <i>B. subtilis</i> identified by 2D gel and MALDI-MS/MS.

<p>Classification of the function of the identified proteins with the 2D mass spectrometry method was based on Gene Ontology from the UniProt Consortium. Each group of protein function is arbitrarily numbered in the bracket. The number (without the bracket) of identified protein classified according to their function is listed according to their increase or loss from the cell wall and the bacteria species.</p