N. elongata Produces Type IV Pili That Mediate Interspecies Gene Transfer with N. gonorrhoeae

The genus Neisseria contains at least eight commensal and two pathogenic species. According to the Neisseria phylogenetic tree, commensals are basal to the pathogens. N. elongata, which is at the opposite end of the tree from N. gonorrhoeae, has been observed to be fimbriated, and these fimbriae are correlated with genetic competence in this organism. We tested the hypothesis that the fimbriae of N. elongata are Type IV pili (Tfp), and that Tfp functions in genetic competence. We provide evidence that the N. elongata fimbriae are indeed Tfp. Tfp, as well as the DNA Uptake Sequence (DUS), greatly enhance N. elongata DNA transformation. Tfp allows N. elongata to make intimate contact with N. gonorrhoeae and to mediate the transfer of antibiotic resistance markers between these two species. We conclude that Tfp functional for genetic competence is a trait of a commensal member of the Neisseria genus. Our findings provide a mechanism for the horizontal gene transfer that has been observed among Neisseria species

Visualization of Sex-Dimorphic Changes in the Intestinal Transcriptome of <b><i>Fabp2</i></b> Gene-Ablated Mice

&lt;b&gt;&lt;i&gt;Background/Aims:&lt;/i&gt;&lt;/b&gt; Sex differences in gene expression program have not been effectively explored at the transcriptome level. We aimed to develop a method for the analysis of transcriptome data to identify sex differences and sex-dimorphic responses to experimental conditions in mice. &lt;b&gt;&lt;i&gt;Methods:&lt;/i&gt;&lt;/b&gt; Profiling of the small intestine transcriptome of chow-fed C57BL/6J (wild-type, WT) and &lt;i&gt;Fabp2&lt;/i&gt;&lt;sup&gt;–/–&lt;/sup&gt; mice was carried out by microarray analysis. Sex-specific and androgynous effects of &lt;i&gt;Fabp2&lt;/i&gt; gene ablation were examined using FlexArray V1.6 by comparing WT to &lt;i&gt;Fabp2&lt;/i&gt;&lt;sup&gt;–/–&lt;/sup&gt; mice. The data generated were exported into a single spreadsheet, collated and transformed to identify the differentially expressed genes for pathway analysis. &lt;b&gt;&lt;i&gt;Results:&lt;/i&gt;&lt;/b&gt; The method revealed enrichment of 17 sex-dimorphic pathways in the small intestine of WT mice compared to only 4 in &lt;i&gt;Fabp2&lt;/i&gt;&lt;sup&gt;–/–&lt;/sup&gt; mice. Comparison of the effects of Fabp2 loss in individual sexes revealed a male-specific upregulation of 5 pathways involved in the production of unsaturated fatty acids, and a female-specific downregulation of pathways involved in xenobiotic metabolism. &lt;b&gt;&lt;i&gt;Conclusions:&lt;/i&gt;&lt;/b&gt; Our approach detected the common as well as sex-differential pathways that are modified due to the loss of Fabp2. These findings suggest that the pathways involved in nutrient and xenobiotic metabolism in the intestine are regulated by sex-specific mechanisms.</jats:p

Attenuation of the Type IV Pilus Retraction Motor Influences Neisseria gonorrhoeae Social and Infection Behavior

Retraction of the type IV pilus (Tfp) mediates DNA uptake, motility, and social and infection behavior in a wide variety of prokaryotes. To date, investigations into Tfp retraction-dependent activities have used a mutant deleted of PilT, the ATPase motor protein that causes the pilus fiber to retract. Delta pilT cells are nontransformable, nonmotile, and cannot aggregate into microcolonies. We tested the hypothesis that these retraction-dependent activities are sensitive to the strength of PilT enzymatic activity by using the pathogen Neisseria gonorrhoeae as a model. We constructed an N. gonorrhoeae mutant with an amino acid substitution in the PilT Walker B box (a substitution of cysteine for leucine at position 201, encoded by PilT(L201C)). Purified PilT(L201C) forms a native hexamer, but mutant hexamers hydrolyze ATP at half the maximal rate. N. gonorrhoeae PilT(L201C) cells produce Tfp fibers, crawl at the same speed as the wild-type (wt) parent, and are equally transformable. However, the social behavior of PilT(L201C) cells is intermediate between the behaviors of wt and Delta pilT cells. The infection behavior of PilT(L201C) is also defective, due to its failure to activate the epidermal growth factor receptor (EGFR)-heparin-binding EGF-like growth factor (HB-EGF) pathway. Our study indicates that pilus retraction, per se, is not sufficient for N. gonorrhoeae micro-colony formation or infectivity; rather, these activities are sensitive to the strength of PilT enzymatic activity. We discuss the implications of these findings for Neisseria pathogenesis in the context of mechanobiology. IMPORTANCE Type IV pili are fibers expressed on the surface of many bacteria. Neisseria gonorrhoeae cells crawl, take up DNA, and communicate with each other and with human cells by retracting these fibers. Here, we show that an N. gonorrhoeae mutant expressing an enzymatically weakened type IV pilus retraction motor still crawls and takes up DNA normally. However, mutant cells exhibit abnormal social behavior, and they are less infective because they fail to activate the epidermal growth factor receptor. Our study shows that N. gonorrhoeae social and infection behaviors are sensitive to the strength of the retraction motor enzyme.HHS|NIH| National Institute of Allergy and Infectious Diseases (NIAID) [R01AI107966]This item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]

A bacterial filter protects and structures the gut microbiome of an insect

Associations with symbionts within the gut lumen of hosts are particularly prone to disruption due to the constant influx of ingested food and non-symbiotic microbes, yet we know little about how partner fidelity is maintained. Here we describe for the first time the existence of a gut morphological filter capable of protecting an animal gut microbiome from disruption. The proventriculus, a valve located between the crop and midgut of insects, functions as a micro-pore filter in the Sonoran Desert turtle ant (Cephalotes rohweri), blocking the entry of bacteria and particles ⩾0.2 μm into the midgut and hindgut while allowing passage of dissolved nutrients. Initial establishment of symbiotic gut bacteria occurs within the first few hours after pupation via oral–rectal trophallaxis, before the proventricular filter develops. Cephalotes ants are remarkable for having maintained a consistent core gut microbiome over evolutionary time and this partner fidelity is likely enabled by the proventricular filtering mechanism. In addition, the structure and function of the cephalotine proventriculus offers a new perspective on organismal resistance to pathogenic microbes, structuring of gut microbial communities, and development and maintenance of host–microbe fidelity both during the animal life cycle and over evolutionary time.This work was funded by NIH grant 5K12GM000708-13. PAPR received support from NSF Grant 0604067 to DEW.Open access.This item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]

Enteropathogenic Escherichia coli regulates host-cell mitochondrial morphology

ABSTRACTThe diarrheagenic pathogen enteropathogenic Escherichia coli is responsible for significant childhood mortality and morbidity. EPEC and related attaching-and-effacing (A/E) pathogens use a type III secretion system to hierarchically deliver effector proteins into host cells and manipulate epithelial structure and function. Subversion of host mitochondrial biology is a key aspect of A/E pathogen virulence strategy, but the mechanisms remain poorly defined. We demonstrate that the early-secreted effector EspZ and the late-secreted effector EspH have contrasting effects on host mitochondrial structure and function. EspZ interacts with FIS1, a protein that induces mitochondrial fragmentation and mitophagy. Infection of epithelial cells with either wildtype EPEC or an isogenic espZ deletion mutant (ΔespZ) robustly upregulated FIS1 abundance, but a marked increase in mitochondrial fragmentation and mitophagy was seen only in ΔespZ-infected cells. FIS1-depleted cells were protected against ΔespZ-induced fission, and EspZ-expressing transfected epithelial cells were protected against pharmacologically induced mitochondrial fission and membrane potential disruption. Thus, EspZ interacts with FIS1 and blocks mitochondrial fragmentation and mitophagy. In contrast to WT EPEC, ΔespH-infected epithelial cells had minimal FIS1 upregulation and exhibited hyperfused mitochondria. Consistent with the contrasting impacts on organelle shape, mitochondrial membrane potential was preserved in ΔespH-infected cells, but profoundly disrupted in ΔespZ-infected cells. Collectively, our studies reveal hitherto unappreciated roles for two essential EPEC virulence factors in the temporal and dynamic regulation of host mitochondrial biology

Un état de la recherche sur la noblesse castillane à la fin du Moyen Age : Beceiro Pita (Isabel) y Cordoba de la Llave (Ricardo), Parentesco, poder y mentalidad. La nobleza castellana, siglos XII-XV, Madrid, C.S.I.C., 1990

Leroy Béatrice. Un état de la recherche sur la noblesse castillane à la fin du Moyen Age : Beceiro Pita (Isabel) y Cordoba de la Llave (Ricardo), Parentesco, poder y mentalidad. La nobleza castellana, siglos XII-XV, Madrid, C.S.I.C., 1990. In: Annales du Midi : revue archéologique, historique et philologique de la France méridionale, Tome 103, N°195, 1991. pp. 379-380

PSII is a conserved antigen across various <i>C</i>. <i>difficile</i> strains.

(A) PSII structure as characterized by Ganeshapillai et al [15]. PSII is a branched, hexasaccharide repeating unit containing phosphate. (B) PSII is detected in diverse C. difficile ribotypes (UD, “undiluted”; the ramp indicates increasing to decreasing concentration from left to right).</p

Transfer of antibiotic resistance marker between <i>N. elongata</i> and <i>N. gonorrhoeae</i>.

a<p>Number of rif^R recipient bacteria/total number of recipient bacteria (see Methods for differential selection of each species.).</p><p>*No growth of <i>N. gonorrhoeae</i> on LB Lennox agar.</p><p>**No growth of <i>N. elongata</i> on GCB/VCN agar. Values represent the average from three independent experiments ± SEM.</p

Role of DUS in DNA transformation by wt <i>N. elongata.</i>

a<p>Transformation frequency is expressed as the number of rifampicin resistant bacteria/total CFUs. Values represent the average from three independent experiments ± SEM. “<” indicates the transformation frequency was below the limit of detection of the assay. “none”: medium only.</p

<i>C</i>. <i>difficile</i> exhibits a CWG layer.

(A-i) Scanning electron micrographs of unstained (left) and ruthenium-red stained (right) C. difficile ribotype 053 strain. (A-ii) Identical to (A-i) but visualized using transmission electron microscopy. Scale bars represent 5μm for (A-i) and 500nm for (A-ii). (B) Transmission electron micrographs of ruthenium red-stained bacteria of ribotype 012 and 053 at 72 hours of growth. The scale bar represents 500nm. The black arrows point to the ruthenium red-stained CWG layer.</p