Bacterial symbionts of a devastating coffee plant pest, the stinkbug Antestiopsis thunbergii (Hemiptera: Pentatomidae).

Stinkbugs of the genus Antestiopsis, so-called antestia bugs or variegated coffee bugs, are notorious pests of coffee plants in Africa. We investigated the symbiotic bacteria associated with Antestiopsis thunbergii, a major coffee plant pest in Rwanda. PCR, cloning, sequencing, and phylogenetic analysis of bacterial genes identified four distinct bacterial lineages associated with A. thunbergii: a gammaproteobacterial gut symbiont and symbionts representing the genera Sodalis, Spiroplasma, and Rickettsia. In situ hybridization showed that the gut symbiont densely occupied the lumen of midgut crypts, whereas the Sodalis symbiont, the Spiroplasma symbiont, and the Rickettsia symbiont sparsely and sporadically infected various cells and tissues. Diagnostic PCR survey of 154 A. thunbergii individuals collected at 8 localities in Rwanda revealed high infection frequencies (100% for the gut symbiont, 51.3% for the Sodalis symbiont, 52.6% for the Spiroplasma symbiont, and 24.0% for the Rickettsia symbiont). These results suggest that the gut symbiont is the primary symbiotic associate of obligate nature for A. thunbergii, whereas the Sodalis symbiont, the Spiroplasma symbiont, and the Rickettsia symbiont are the secondary symbiotic associates of facultative nature. We observed high coinfection frequencies, i.e., 7.8% of individuals with quadruple infection with all the symbionts, 32.5% with triple infections with the gut symbiont and two of the secondary symbionts, and 39.6% with double infections with the gut symbiont and any of the three secondary symbionts, which were statistically not different from the expected coinfection frequencies and probably reflected random associations. The knowledge of symbiotic microbiota in A. thunbergii will provide useful background information for controlling this devastating coffee plant pest.

Characterization of intersex production in Trichogramma kaykai infected with parthenogenesis-inducing Wolbachia.

Sexually aberrant individuals, displaying both male and female characteristics, are rare in occurrence but are documented throughout the animal kingdom. In parasitoid wasps of the genus Trichogramma, such individuals typically appear as a result of rearing Wolbachia-infected thelytokous wasps at high temperatures. Sexually aberrant Trichogramma have been referred to interchangeably in the literature as gynandromorphs, sexual mosaics and intersexes. However, accurately used, the terms "gynandromorph" and "sexual mosaic" describe an individual composed of a mixture of genetically distinct tissues corresponding to the sexual phenotypes observed, while "intersex" refers to an individual having a uniform genetic constitution but with some tissues exhibiting sexual phenotypes conflicting with the associated genotype. Here, we investigate the heat-induced production of sexually aberrant offspring by thelytokous Trichogramma kaykai. Aberrant individuals were rare, but each was characterized as one of 11 morphotypes ranging from very feminine to very masculine. Overall, the production of aberrant individuals increased with time from the onset of maternal oviposition. However, while the production of males also increased with time, the degree of masculinity of aberrant individuals did not; the different morphotypes appeared to be produced haphazardly. We conclude that the aberrant individuals produced by T. kaykai are actually intersexes and not gynandromorphs. The wasp's close association with Wolbachia and the absence of intersexes in uninfected populations allow us to discuss a possible origin of the condition.

A relaxed growth modeling framework for controlling growth-induced residual stresses.

BACKGROUND: Constitutive models of the mechanical response of soft tissues have been established and are widely accepted, but models of soft tissues remodeling are more controversial. Specifically for growth, one important question arises pertaining to residual stresses: existing growth models inevitably introduce residual stresses, but it is not entirely clear if this is physiological or merely an artifact of the modeling framework. As a consequence, in simulating growth, some authors have chosen to keep growth-induced residual stresses, and others have chosen to remove them. METHODS: In this paper, we introduce a novel "relaxed growth" framework allowing for a fine control of the amount of residual stresses generated during tissue growth. It is a direct extension of the classical framework of the multiplicative decomposition of the transformation gradient, to which an additional sub-transformation is introduced in order to let the original unloaded configuration evolve, hence relieving some residual stresses. We provide multiple illustrations of the framework mechanical response, on time-driven constrained growth as well as the strain-driven growth problem of the artery under internal pressure, including the opening angle experiment. FINDINGS: The novel relaxed growth modeling framework introduced in this paper allows for a better control of growth-induced residual stresses compared to standard growth models based on the multiplicative decomposition of the transformation gradient. INTERPRETATION: Growth-induced residual stresses should be better handled in soft tissues biomechanical models, especially in patient-specific models of diseased organs that are aimed at augmented diagnosis and treatment optimization.

Evolution of the passive film and organic constituents at the surface of stainless steel immersed in fresh water.

The evolution of the surface of a conventional stainless steel (AISI 316L) immersed in aqueous medium simulating fresh water (pH approximately 8) was studied using XPS and AFM. A detailed analysis of XPS spectra allowed a distinction to be made between oxygen of organic and inorganic nature. During the first 48 h, the main changes concern the inorganic phase: the oxygen concentration in the passive layer increases, owing both to oxidation of metal elements, including conversion of Fe(II) to Fe(III), and to hydration; the molar ratio of oxidized species Fe(ox)/Cr(ox) decreases slightly; the formation of colloidal particles, presumably made of ferric hydroxide, is observed by AFM. After longer periods of immersion, the Fe(ox)/Cr(ox) is higher, while the coating of colloidal particles reaches a full surface coverage. The amount of organic compounds increases further and the XPS spectra reveal the accumulation of polysaccharides and proteins, which indicate that these organic compounds are of biological origin.

Ennoblement of stainless steel in the presence of glucose oxidase: nature and role of interfacial processes.

The ennoblement of the free corrosion potential (E(corr)) of AISI 316L stainless steel which did not occur in synthetic fresh water (SFW), was observed after introduction of glucose oxidase (Gox) and glucose, or of hydrogen peroxide (H(2)O(2)). The composition of the surface was monitored using AFM and XPS, a detailed XPS analysis being based on the discrimination between oxygen of organic and inorganic nature proposed in a previous study. In H(2)O(2) medium, the main changes regarding the inorganic phase were the increase of the oxygen concentration in the passive film, the increase of the molar concentration ratio of oxidized species Fe(ox)/Cr(ox) and the growth of nanoparticles, presumably made of ferric oxide/hydroxide. In Gox medium, no significant changes were observed in both oxygen concentration and Fe(ox)/Cr(ox) ratio, but the density of colloidal particles decreased, indicating a dissolution of Fe oxide/hydroxide under the influence of gluconate. In contrast with H(2)O(2), in SFW and Gox the amount of organic compounds increased due to the accumulation of polysaccharides and proteins. The influence of glucose oxidase on the ennoblement of stainless steel is not due to indirect effects of H(2)O(2) through the change of surface composition. The E(corr) ennoblement seems to be directly due to the presence of H(2)O(2) and to the electrochemical behavior of H(2)O(2) and related oxygen species. This consideration is important for understanding and controlling microbial influenced corrosion.

Equilibrated warping: Finite element image registration with finite strain equilibrium gap regularization.

In this paper, we propose a novel continuum finite strain formulation of the equilibrium gap regularization for image registration. The equilibrium gap regularization essentially penalizes any deviation from the solution of a hyperelastic body in equilibrium with arbitrary loads prescribed at the boundary. It thus represents a regularization with strong mechanical basis, especially suited for cardiac image analysis. We describe the consistent linearization and discretization of the regularized image registration problem, in the framework of the finite elements method. The method is implemented using FEniCS & VTK, and distributed as a freely available python library. We show that the equilibrated warping method is effective and robust: regularization strength and image noise have minimal impact on motion tracking, especially when compared to strain-based regularization methods such as hyperelastic warping. We also show that equilibrated warping is able to extract main deformation features on both tagged and untagged cardiac magnetic resonance images.

The Still-Face: A Greater Challenge for Infants of Mothers With Borderline Personality Disorder.

The main aim of this study was to ascertain whether infants as young as 3 months of age, whose mothers suffer from borderline personality disorder (BPD), are already at risk of greater dysregulation than infants of mothers without BPD when faced with a minor stressful experience. Nineteen mothers diagnosed with BPD and 41 controls with no history of psychopathology and their 3-month-old infants were observed using Tronick's Face-to-Face Still-Face paradigm. The authors found that infants whose mothers have BPD express less positive vocalizations and less nonautonomic self-regulation than infants of mothers with no psychopathology. The stress of the Still-Face episode affects their gaze and self-regulation behaviors more strongly than those of infants of controls. The Reunion episode seems particularly challenging for mothers with BPD, who show fewer smiles and an increase in intrusive behavior. Because infants and their mothers with BPD are already dysregulated at 3 months postpartum, envisaging very early intervention seems warranted.

Modeling Pathologies of Diastolic and Systolic Heart Failure.

Chronic heart failure is a medical condition that involves structural and functional changes of the heart and a progressive reduction in cardiac output. Heart failure is classified into two categories: diastolic heart failure, a thickening of the ventricular wall associated with impaired filling; and systolic heart failure, a dilation of the ventricles associated with reduced pump function. In theory, the pathophysiology of heart failure is well understood. In practice, however, heart failure is highly sensitive to cardiac microstructure, geometry, and loading. This makes it virtually impossible to predict the time line of heart failure for a diseased individual. Here we show that computational modeling allows us to integrate knowledge from different scales to create an individualized model for cardiac growth and remodeling during chronic heart failure. Our model naturally connects molecular events of parallel and serial sarcomere deposition with cellular phenomena of myofibrillogenesis and sarcomerogenesis to whole organ function. Our simulations predict chronic alterations in wall thickness, chamber size, and cardiac geometry, which agree favorably with the clinical observations in patients with diastolic and systolic heart failure. In contrast to existing single- or bi-ventricular models, our new four-chamber model can also predict characteristic secondary effects including papillary muscle dislocation, annular dilation, regurgitant flow, and outflow obstruction. Our prototype study suggests that computational modeling provides a patient-specific window into the progression of heart failure with a view towards personalized treatment planning.

A computational model that predicts reverse growth in response to mechanical unloading.

Ventricular growth is widely considered to be an important feature in the adverse progression of heart diseases, whereas reverse ventricular growth (or reverse remodeling) is often considered to be a favorable response to clinical intervention. In recent years, a number of theoretical models have been proposed to model the process of ventricular growth while little has been done to model its reverse. Based on the framework of volumetric strain-driven finite growth with a homeostatic equilibrium range for the elastic myofiber stretch, we propose here a reversible growth model capable of describing both ventricular growth and its reversal. We used this model to construct a semi-analytical solution based on an idealized cylindrical tube model, as well as numerical solutions based on a truncated ellipsoidal model and a human left ventricular model that was reconstructed from magnetic resonance images. We show that our model is able to predict key features in the end-diastolic pressure-volume relationship that were observed experimentally and clinically during ventricular growth and reverse growth. We also show that the residual stress fields generated as a result of differential growth in the cylindrical tube model are similar to those in other nonidentical models utilizing the same geometry.

Heterogeneous growth-induced prestrain in the heart.

Even when entirely unloaded, biological structures are not stress-free, as shown by Y.C. Fung׳s seminal opening angle experiment on arteries and the left ventricle. As a result of this prestrain, subject-specific geometries extracted from medical imaging do not represent an unloaded reference configuration necessary for mechanical analysis, even if the structure is externally unloaded. Here we propose a new computational method to create physiological residual stress fields in subject-specific left ventricular geometries using the continuum theory of fictitious configurations combined with a fixed-point iteration. We also reproduced the opening angle experiment on four swine models, to characterize the range of normal opening angle values. The proposed method generates residual stress fields which can reliably reproduce the range of opening angles between 8.7±1.8 and 16.6±13.7 as measured experimentally. We demonstrate that including the effects of prestrain reduces the left ventricular stiffness by up to 40%, thus facilitating the ventricular filling, which has a significant impact on cardiac function. This method can improve the fidelity of subject-specific models to improve our understanding of cardiac diseases and to optimize treatment options.

A comparison between the elemental surface compositions and electrokinetic properties of oral streptococci with and without adsorbed salivary constituents.

In order to characterize the functional cell surface, isoelectric points and elemental surface concentration, the ratios of nitrogen, oxygen and phosphorus to carbon of saliva-coated strains were determined by pH-dependent zeta potential measurements and X-ray photoelectron spectroscopy and compared with those of uncoated strains. The measurements of potential were carried out on completely hydrated cells, whereas the spectroscopy was on freeze-dried micro-organisms. The small increase in the nitrogen:carbon surface concentration ratio of saliva-coated streptococci in comparison to uncoated strains varied from 0.001 (Streptococcus mitis BA) to 0.029 (Streptococcus sanguis CH3) and was concurrent with an increase of the isoelectric point, ranging from 0.0 to 0.9. Increases in the oxygen:carbon ratio ranged from 0.006 (Strep. mitis BA) to 0.041 (Streptococcus mutans NS), whereas the phosphorus:carbon surface concentration ratio was unchanged after saliva treatment. Despite the fact that isoelectric and compositional measurements were made in different states of surface hydration, a decrease in the nitrogen:carbon ratio accompanied by an increase in oxygen:carbon ratio, was related to a decrease of the isoelectric point of the saliva-coated strains, and so analogous with previous observations for uncoated strains. Although there were changes in the physico-chemical properties of the strains upon saliva coating, all more or less kept their own surface identity despite adsorption of salivary constituents, possibly indicating some capacity to protect their own physico-chemical identity.

Surface free energies and elemental surface compositions of human enamel after application of commercially available mouthrinses and adsorption of salivary constituents.

The adsorption of active agents from six commercially available mouthrinses to ground and polished enamel, with and without adsorbed salivary constituents, was monitored by contact angle measurements and X-ray Photoelectron Spectroscopy (XPS). Human enamel samples were treated with mouthrinses containing chlorhexidine (Peridex), stannous fluoride/amine fluoride (Meridol), thymol/benzoic acid (Listerine), sanguinarine (Veadent), sodium fluoride (Prodent), or cetylpyridinium chloride (Merocet). XPS indicated a sizeable adsorption of both active and non-active components for all products. After treatment, all enamel surface free energies increased except for the stannous fluoride/amine fluoride containing mouthrinse. It is suggested that non-active components in the products cause an increase in surface free energy. Despite this thermodynamically unfavorable increase in surface free energy, all rinses have plaque reducing effects, indicating that this unfavorable surface characteristic is overruled by the antibacterial properties of the components. Replacement of non-active components by less adsorbing surfactants could increase the efficiency of the products tested.

Assignment of 12 loci to rat chromosome 5: evidence that this chromosome is homologous to mouse chromosome 4 and to human chromosomes 9 and 1 (1p arm).

Twelve loci have been assigned to rat chromosome 5: aldolase B (ALDOB), atrial natriuretic factor (ANF = pronatriodilatin, PND), D4RP1, DSI1, galactosyltransferase (GGTB2), glucose transporter (GLUT1), interferon alpha 1 and related interferon alpha (INFA), interferon beta (INFB), lymphocyte-specific protein-tyrosine kinase (LCK), oncogene MOS, alpha 2U-globulin (major urinary protein, MUP), and orosomucoid (ORM, also called alpha 1-acid glycoprotein, AGP). Among these, the interferon alpha and beta genes map in the q22-23 region, which also contains a transformation suppressor gene (SAI1). The other loci reside outside this region. This study also indicated that the rat genome contains 2 LCK genes, unlike the human and murine genomes. These new assignments on rat chromosome 5 demonstrate that this chromosome is highly homologous to mouse chromosome 4 and carries synteny groups conserved on human chromosome 9 (interferon alpha and beta, galactosyltransferase, orosomucoid, and aldolase B genes) and on the short arm of human chromosome 1 (MYCL, glucose transporter, protein kinase LCK, and atrial natriuretic factor genes).

Cetylpyridinium chloride adsorption on the wettability and elemental surface composition of human enamel.

To determine the influence of cetylpyridinium chloride (CPC) adsorption on the wettability and elemental surface composition of human enamel, with and without adsorbed salivary constituents, surface-free energies and elemental compositions were determined. The surface-free energies were estimated from contact angle measurements; whereas the elemental compositions were determined by X-ray photoelectron spectroscopy. Surface-free energies of ground and polished enamel (88 +/- 8 mJ.m-2 and saliva-coated enamel (103 +/- 4) became similar (109-112) upon adsorption of CPC. Also, the N/C concentration ratios of the ground and polished enamel surface (0.06) and saliva-coated enamel (0.21) become equal upon CPC adsorption. The N/C concentration ratio after CPC adsorption (N/C = 0.04) corresponds with the value expected on basis of the molecular structure of CPC. The strongest evidence for adsorption of CPC to both ground and polished enamel and saliva-coated enamel is presented by the double nitrogen N1s peak. This double nitrogen1s peak is not observed for ground and polished enamel nor for enamel with a salivary coating on top of adsorbed CPC, which indicates that adsorbed CPC can be completely screened by salivary proteins. This study demonstrates that CPC has a definite capacity to adsorb both on ground and polished enamel as well as on pellicle-coated enamel.

Elemental surface concentration ratios and surface free energies of human enamel after application of chlorhexidine and adsorption of salivary constituents.

In vitro adsorption of chlorhexidine from a commercially available chlorhexidine-containing (0.12%) mouthrinse (Peridex) on both ground and polished and on saliva-coated enamel was studied by X-ray photoelectron spectroscopy and contact angle measurements. Furthermore, adsorption of salivary constituents was studied on chlorhexidine-treated enamel. Changes in the elemental surface composition obtained by X-ray photoelectron spectroscopy clearly demonstrated adsorption of chlorhexidine from the mouthrinse as indicated by increased N and C signals which were in all cases accompanied by a higher enamel surface free energy, estimated from the contact angle data. In addition, it was found that salivary constituents adsorb less to chlorhexidine-treated enamel than to ground and polished enamel and, moreover, that adsorbed salivary constituents were desorbed by chlorhexidine. In vivo, the effect of a 3-week use of chlorhexidine was compared with the use of a placebo and habitual oral hygiene of 10 volunteers by means of clinical contact angle measurements. Also in vivo adsorption of chlorhexidine yielded elevated surface free energies with respect to habitual oral hygiene or a placebo. Thus in vivo, the well-known favourable effects of the bactericidal properties of chlorhexidine completely overrule the unfavourable effects of high enamel surface free energies.

Spoligologos: a bioinformatic approach to displaying and analyzing Mycobacterium tuberculosis data.

Spacer oligonucleotide (spoligotyping) analysis is a rapid polymerase chain reaction-based method of DNA fingerprinting the Mycobacterium tuberculosis complex. We examined spoligotype data using a bioinformatic tool (sequence logo analysis) to elucidate undisclosed phylogenetic relationships and gain insights into the global dissemination of strains of tuberculosis. Logo analysis of spoligotyping data provides a simple way to describe a fingerprint signature and may be useful in categorizing unique spoligotypes patterns as they are discovered. Large databases of DNA fingerprint information, such as those from the U.S. National Tuberculosis Genotyping and Surveillance Network and the European Concerted Action on Tuberculosis, contain information on thousands of strains from diverse regions. The description of related spoligotypes has depended on exhaustive listings of the individual spoligotyping patterns. Logo analysis may become another useful graphic method of visualizing and presenting spoligotyping clusters from these databases.