Quorum Sensing Peptides Selectively Penetrate the Blood-Brain Barrier

Bacteria communicate with each other by the use of signaling molecules, a process called ‘quorum sensing’. One group of quorum sensing molecules includes the oligopeptides, which are mainly produced by Gram-positive bacteria. Recently, these quorum sensing peptides were found to biologically influence mammalian cells, promoting i.a. metastasis of cancer cells. Moreover, it was found that bacteria can influence different central nervous system related disorders as well, e.g. anxiety, depression and autism. Research currently focuses on the role of bacterial metabolites in this bacteria-brain interaction, with the role of the quorum sensing peptides not yet known. Here, three chemically diverse quorum sensing peptides were investigated for their brain influx (multiple time regression technique) and efflux properties in an in vivo mouse model (ICR-CD-1) to determine blood-brain transfer properties: PhrCACET1 demonstrated comparatively a very high initial influx into the mouse brain (K_in = 20.87 μl/(g×min)), while brain penetrabilities of BIP-2 and PhrANTH2 were found to be low (K_in = 2.68 μl/(g×min)) and very low (K_in = 0.18 μl/(g×min)), respectively. All three quorum sensing peptides were metabolically stable in plasma (in vitro) during the experimental time frame and no significant brain efflux was observed. Initial tissue distribution data showed remarkably high liver accumulation of BIP-2 as well. Our results thus support the potential role of some quorum sensing peptides in different neurological disorders, thereby enlarging our knowledge about the microbiome-brain axis.     

Fitness costs of worker specialization for ant societies

Division of labour is of fundamental importance for the success of societies, yet little is known about how individual specialization affects the fitness of the group as a whole. While specialized workers may be more efficient in the tasks they perform than generalists, they may also lack the flexibility to respond to rapid shifts in task needs. Such rigidity could impose fitness costs when societies face dynamic and unpredictable events, such as an attack by socially parasitic slavemakers. Here, we experimentally assess the colony-level fitness consequences of behavioural specialization in Temnothorax longispinosus ants that are attacked by the slavemaker ant T. americanus. We manipulated the social organization of 102 T. longispinosus colonies, based on the behavioural responses of all 3842 workers. We find that strict specialization is disadvantageous for a colony''s annual reproduction and growth during slave raids. These fitness costs may favour generalist strategies in dynamic environments, as we also demonstrate that societies exposed to slavemakers in the field show a lower degree of specialization than those originating from slavemaker-free populations. Our findings provide an explanation for the ubiquity of generalists and highlight their importance for the flexibility and functional robustness of entire societies.     

Using Ecological Momentary Assessment in Testing the Effectiveness of an Alcohol Intervention: A Two-Arm Parallel Group Randomized Controlled Trial

Background

Alcohol consumption of college students has a fluctuating nature, which might impact the measurement of intervention effects. By using 25 follow-up time-points, this study tested whether intervention effects are robust or might vary over time.

Methods

Data were used from a two-arm parallel group randomized controlled trial applying ecological momentary assessment (EMA) with 30 data time-points in total. Students between 18 and 24 years old who reported heavy drinking in the past six months and who were ready to change their alcohol consumption were randomly assigned to the experimental (n = 456: web-based brief alcohol intervention) and control condition (n = 451: no intervention). Outcome measures were weekly alcohol consumption, frequency of binge drinking, and heavy drinking status.

Results

According to the intention-to-treat principle, regression analyses revealed that intervention effects on alcohol consumption varied when exploring multiple follow-up time-points. Intervention effects were found for a) weekly alcohol consumption at 1, 2, 3, 4, and 7 weeks follow-up, b) frequency of binge drinking at 1, 2, 7, and 12 weeks follow-up, and c) heavy drinking status at 1, 2, 7, and 16 weeks follow-up.

Conclusions

This research showed that the commonly used one and six month follow-up time-points are relatively arbitrary and not using EMA might bring forth erroneous conclusions on the effectiveness of interventions. Therefore, future trials in alcohol prevention research and beyond are encouraged to apply EMA when assessing outcome measures and intervention effectiveness.

Trial registration

Netherlands Trial Register NTR2665     

Association of cytomegalovirus and other pathogens with frailty and diabetes mellitus,but not with cardiovascular disease and mortality in psycho-geriatric patients; a prospective cohort study

Background

Studies about associations of infections with herpes viruses and other pathogens, such as Chlamydia pneumoniae (CP) and Helicobacter pylori (HP) with cardiovascular disease (CVD), diabetes mellitus (DM), frailty and/or mortality are conflicting. Since high levels of antibodies against these pathogens occur in the elderly, the role of these pathogens in morbidity and mortality of vulnerable elderly was explored.

Results

Blood samples of 295 community dwelling psycho-geriatric patients were tested for IgG antibodies to herpes simplex virus type 1 and 2, varicella zoster virus, Epstein Barr virus (EBV), cytomegalovirus (CMV), human herpes virus type 6 (HHV6), CP and HP. Frailty was defined with an easy-to-use previously described frailty risk score. Relative risks (RR) with 95% confidence intervals were calculated to evaluate associations between CVD, DM, frailty and pathogens. Pathogens as a predictor for subsequent mortality were tested using Kaplan Meier analyses and Cox proportional hazard models. The mean age was 78 (SD: 6.7) years, 20% died, 44% were defined as frail, 20% had DM and 49% had CVD. Presence of CMV antibody titers was associated with frailty, as shown by using both qualitative and quantitative tests, RR ratio 1.4 (95% CI: 1.003-2.16) and RR ratio 1.5 (95% CI: 1.06-2.30), respectively. High IgG antibody titers of HHV6 and EBV were associated with DM, RR ratio 3.3 (95% CI: 1.57-6.49). None of the single or combined pathogens were significantly associated with mortality and/or CVD.

Conclusions

Prior CMV infection is associated with frailty, which could be in line with the concept that CMV might have an important role in immunosenescence, while high IgG titers of HHV6 and EBV are associated with DM. No association between a high pathogen burden and morbidity and/or mortality could be demonstrated.

     

A Clinical Evaluation of Statin Pleiotropy: Statins Selectively and Dose-Dependently Reduce Vascular Inflammation

Statins are thought to reduce vascular inflammation through lipid independent mechanisms. Evaluation of such an effect in atherosclerotic disease is complicated by simultaneous effects on lipid metabolism. Abdominal aortic aneurysms (AAA) are part of the atherosclerotic spectrum of diseases. Unlike atherosclerotic occlusive disease, AAA is not lipid driven, thus allowing direct evaluation of putative anti-inflammatory effects. The anti-inflammatory potency of increasing doses (0, 20 or 40 mg/day) simvastatin or atorvastatin was evaluated in 63 patients that were at least 6 weeks on statin therapy and who underwent open AAA repair. A comprehensive analysis using immunohistochemistry, mRNA and protein analyses was applied on aortic wall samples collected during surgery. The effect of statins on AAA growth was analyzed in a separate prospective study in incorporating 142 patients. Both statins equally effectively and dose-dependently reduced aortic wall expression of NFκB regulated mediators (i.e. IL-6 (P<0.001) and MCP-1 (P<0.001)); shifted macrophage polarization towards a M2 phenotype (P<0.0003); selectively reduced macrophage-related markers such as cathepsin K and S (P<0.009 and 0.0027 respectively), and ALOX5 (P<0.0009), and reduced vascular wall NFκB activity (40 mg/day group, P<0.016). No effect was found on other cell types. Evaluation of the clinical efficacy of statins to reduce AAA progression did not indicate an effect of statins on aneurysm growth (P<0.337). Hence, in the context of AAA the clinical relevance of statins pleiotropy appears minimal.     

Suitability testing of commercial solid-phase extraction sorbents for sample clean-up in systematic toxicological analysis using liquid chromatography-(tandem) mass spectrometry

An entire series of SPE sorbents, classified into three different categories (apolar, mixed-mode and polymeric) was evaluated for sample preparation of a data-dependent LC-MS-MS "general unknown" screening procedure. An extraction procedure was formulated for each individual column, in agreement with the enclosed instructions, according to the characteristics of each packing. For conciseness, only neutral and basic compounds were chosen for this sorbent suitability test. Thus, the goal of our research was to select the best sorbent with regard to extraction yield and cleanliness of the extracts, all with respect to data-dependent acquisition (DDA) mediated LC-MS-MS general unknown screening. We conclude that for that purpose an Isolute C(8) sorbent performs best in terms of extraction yield and clean-up potential.     

Low Empathy in Deaf and Hard of Hearing (Pre)Adolescents Compared to Normal Hearing Controls

Objective

The purpose of this study was to examine the level of empathy in deaf and hard of hearing (pre)adolescents compared to normal hearing controls and to define the influence of language and various hearing loss characteristics on the development of empathy.

Methods

The study group (mean age 11.9 years) consisted of 122 deaf and hard of hearing children (52 children with cochlear implants and 70 children with conventional hearing aids) and 162 normal hearing children. The two groups were compared using self-reports, a parent-report and observation tasks to rate the children’s level of empathy, their attendance to others’ emotions, emotion recognition, and supportive behavior.

Results

Deaf and hard of hearing children reported lower levels of cognitive empathy and prosocial motivation than normal hearing children, regardless of their type of hearing device. The level of emotion recognition was equal in both groups. During observations, deaf and hard of hearing children showed more attention to the emotion evoking events but less supportive behavior compared to their normal hearing peers. Deaf and hard of hearing children attending mainstream education or using oral language show higher levels of cognitive empathy and prosocial motivation than deaf and hard of hearing children who use sign (supported) language or attend special education. However, they are still outperformed by normal hearing children.

Conclusions

Deaf and hard of hearing children, especially those in special education, show lower levels of empathy than normal hearing children, which can have consequences for initiating and maintaining relationships.     

ERECTA controls low light intensity-induced differential petiole growth independent of phytochrome B and cryptochrome 2 action in Arabidopsis thaliana

Plants can respond quickly and profoundly to changes in their environment. Several species, including Arabidopsis thaliana, are capable of differential petiole growth driven upward leaf movement (hyponastic growth) to escape from detrimental environmental conditions. Recently, we demonstrated that the leucine-rich repeat receptor-like Ser/Thr kinase gene ERECTA, explains a major effect Quantitative Trait Locus (QTL) for ethylene-induced hyponastic growth in Arabidopsis. Here, we demonstrate that ERECTA controls the hyponastic growth response to low light intensity treatment in a genetic background dependent manner. Moreover, we show that ERECTA affects low light-induced hyponastic growth independent of Phytochrome B and Cryptochrome 2 signaling, despite that these photoreceptors are positive regulators of low light-induced hyponastic growth.Key words: hyponastic growth, petiole, Arabidopsis, low light, ERECTA, differential growth, phytochrome B, cryptochrome 2Plants must adjust growth and reproduction to adverse environmental conditions. Among the strategies that plants employ to escape from unfavorable conditions is differential petiole growth-driven upward leaf movement, called hyponastic growth. Arabidopsis thaliana is able to exhibit a marked hyponastic response upon flooding, which is triggered by endogenous accumulation of the gaseous phytohormone ethylene.¹ Moreover, a similar response is triggered upon low light intensity perception and in response to supra-optimal temperatures.^2–5 By tilting the leaves to a more vertical position during submergence and shading, the plants restore contact with the atmosphere and light, respectively. The kinetics of the hyponastic growth response induced by the various stimuli is remarkably similar. This led to the hypothesis that shared functional genetic components may be employed to control hyponastic growth. Yet, at least part of the signaling cascades is parallel, as the hormonal control of the response differs between the stimuli. Low light-induced hyponastic growth for example does not require ethylene action.² Whereas the response to heat is antagonized by this hormone.⁵ The abiotic stress hormone abscisic acid (ABA) antagonizes ethylene-induced hyponastic growth and stimulates heat-induced hyponastic growth.^5,6 Moreover, ethylene-induced hyponasty does not involve auxin action⁷ whereas both heat- and low light-induced hyponasty require functional auxin signaling and transport components.^2,5In our recent paper, published in The Plant Journal,⁸ we employed Quantitative Trait Locus (QTL) analysis to identify loci involved in the control of ethylene-induced hyponastic petiole growth. By analyzing induced mutants and by complementation analysis of naturally occurring mutant accessions, we found that the leucine-rich repeat receptor-like Ser/Thr kinase gene ERECTA (ER) is a positive regulator of ethylene-induced hyponastic growth and most likely is causal to one of the identified QTLs. In addition, we demonstrated that the ER dependency is not via ER mediated control of ethylene production or sensitivity.Since low light-induced hyponasty does not require ethylene action,² ER may be part of the proposed shared signaling cascade leading to hyponastic growth where ethylene and low light signals meet. Therefore, we studied low light intensity-induced hyponasty in various erecta mutants. Moreover, natural occurring er mutant accessions complemented with a functional, Col-0 derived, ER allele were tested. The response of Lan-0 (Lan-0; with functional ER) to low light was indistinguishable from the response of Landsberg erecta (Ler) (Fig. 1A). However, complemented Ler (ER-Ler) showed an enhanced response compared to Ler (Fig. 1B). The response of mutant er105 was slightly attenuated compared to the wild type Columbia-0 (Fig. 1C). Mutant er104, however, showed an indistinguishable hyponastic growth phenotype to low light compared to the wild type Wassilewskija-2 (Ws-2) (Fig. 1D). Complementation of the natural occurring erecta mutant accession Vancouver-0 (Van-0) resulted in an enhanced hyponastic growth response to low light (Fig. 1E), whereas this was not the case for Hiroshima-1 (Hir-1) (Fig. 1F). Together, these data suggest that ER acts as positive regulator of low light-induced hyponastic growth and therefore may be part of the shared signaling cascade towards differential petiole growth. Yet, the effect is strongly dependent on the genetic background since the effects were not observed in every accession tested.Open in a separate windowFigure 1ERECTA involvement in low light-induced hyponasty. Effect of exposure to low light (spectral neutral reduction in light intensity from 200 to 20 µmol m⁻² s⁻¹) on the kinetics of hyponastic petiole growth in Arabidopsis thaliana. (A) mutant (circles) Ler and wild type (dashed line) Lan-0, (B) Ler and Ler complemented (ER-; squares) with the Col-0 ERECTA allele (ER-Ler), (C) er105 and Col-0 wild type, (D) er104 and Ws-2 wild type, (E) natural mutant Van-0 and Van-0 complemented with the Col-0 ER allele (ER-Van-0), (F) natural mutant Hir-1 and Hir-1 complemented with the Col-0 ER allele (ER-Hir-1). Petiole angles were measured using time-lapse photography and subsequent image analysis. Data is pairwise subtracted, which corrects for diurnal petiole movement in control conditions. For details on this procedure, growth conditions and materials, transformation protocol, treatments, data acquirement and all analyses see.^1,8 Error bars represent standard errors; n ≥ 12.Phytochrome B (PhyB) and Cryptochrome 2 (Cry2) photoreceptor proteins are required for a full induction of low light-induced hyponastic growth.² We transformed the phyb5 cry2 mutant9 (Ler genetic background) with Col-0 derived ER. This complementation did not restore the ability of phyb5 cry2 to induce hyponastic growth to neither ethylene (data not shown) nor low light conditions (Fig. 2A). Mutant phyb5 cry2 plants have a typical constitutive shade avoidance phenotype, reflected by severely elongated organs. This includes enhanced inflorescence and silique length and thin inflorescences (Fig. 2B-D). Complementation with ER resulted in a significant additional effect on these parameters (Fig. 2B-D). Together, this suggests that ER is not an integral part of PhyB nor Cry2 signaling with respect to (hyponastic) growth. Moreover, PhyB and Cry2 control of plant architecture does not require ER action. Rather, ER seems to mediate growth via genetic interaction with light-reliant growth mechanisms, instead of being downstream of photoreceptor action. Studies on the effects of ER on shade avoidance responses and various hormone responses, including cytokinin and auxin, led to the similar conclusion, suggesting a possible role for ER as a molecular hub coordinating light- and hormone-mediated plant growth.^10,11 One could speculate that ER fine-tunes other (than light) environmental clues with light signaling components. A comparable conclusion was drawn previously for gibberellin (GA) reliant growth mechanisms, as er enhanced the negative effect on plant size of the short internode (shi) mutation12 and er represses the positive effect of the spindly mutation in a GA independent manner.¹³Open in a separate windowFigure 2Effects of ERECTA on light signaling. (A) Effect of exposure to low light (spectral neutral reduction in light intensity from 200 to 20 µmol m⁻² s⁻¹) on the kinetics of hyponastic petiole growth of Ler (dashed lines), the photoreceptor double mutant phyb5 cry2 (circles) and this mutant complemented with the Col-0 ERECTA (ER-phyb cry2; squares). For details see legend Figure 1. (B) Plant height, (C) silique length and (D) inflorescence stem thickness of the above mentioned lines. These parameters were measured when the last flower on the plant developed a silique. Plant height was measured from root/shoot junction to inflorescence top. Stem thickness was measured ∼1 cm above the root/shoot junction with a caliper and silique lengths were measured from representative pedicels in the top ∼10 cm of the main inflorescence stem. Error bars represent standard errors; n ≥ 12. Significance levels; *p < 0.05; **p < 0.01; ***p < 0.001; ns = non significant, by Students t-test.