The plane of bacterial cell division must be precisely positioned. In the bacterium Myxococcus xanthus, the proteins PomX and PomY form a large cluster, which is tethered to the nucleoid by the ...ATPase PomZ and moves in a stochastic but biased manner toward midcell where it initiates cell division. Previously, a positioning mechanism based on the fluxes of PomZ on the nucleoid was proposed. However, the cluster dynamics was analyzed in a reduced, one-dimensional geometry. Here, we introduce a mathematical model that accounts for the three-dimensional shape of the nucleoid, such that nucleoid-bound PomZ dimers can diffuse past the cluster without interacting with it. Using stochastic simulations, we find that the cluster still moves to and localizes at midcell. Redistribution of PomZ by diffusion in the cytosol is essential for this cluster dynamics. Our mechanism also positions two clusters equidistantly on the nucleoid, as observed for low-copy-number plasmid partitioning. We conclude that a flux-based mechanism allows for cluster positioning in a biologically realistic three-dimensional cell geometry.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Background Careful patient selection is the prerequisite to raise transplant benefit. In lung transplant (LT) candidates, the effect of body mass index (BMI) on postoperative outcome remains ...controversial, possibly due to the inaccuracy of BMI in discriminating between fat and muscle mass. We therefore hypothesized that assessment of body composition by muscle mass measures is more accurate than by BMI regarding postoperative outcome. Methods All LT recipients from 2011 to 2014 were included and retrospectively analyzed. Lean psoas area (LPA) was assessed from pretransplant computed tomography scans, and associations with postoperative outcomes were investigated. Results Included were 103 consecutive LT recipients with a mean pre-LT BMI of 22.0 ± 4.0 kg/m2 and a mean LPA of 22.3 ± 8.3 cm2 . LPA was inversely associated with length of mechanical ventilation ( p = 0.03), requirement of tracheostomy ( p = 0.035), and length of stay in the intensive care unit ( p = 0.02), while controlling for underlying disease, BMI, sex, age, and procedure; in contrast, BMI was not ( p = 0.25, p = 0.54, and p = 0.42, respectively.). Multiple regression analysis revealed that the 6-minute walk distance at the end of pulmonary rehabilitation was significantly associated with LPA ( p = 0.02). Conclusions LPA can easily be assessed in LT candidates as part of pretransplant evaluation and was significantly associated with short-term outcome, whereas BMI was not. Assessment of LPA may provide additional information on body composition beyond BMI. However, the clinical utility has to be further evaluated.
Cell division site positioning is precisely regulated but the underlying mechanisms are incompletely understood. In the social bacterium
the ~15 MDa tripartite PomX/Y/Z complex associates with and ...translocates across the nucleoid in a PomZ ATPase-dependent manner to directly position and stimulate formation of the cytokinetic FtsZ-ring at midcell, and then undergoes fission during division. Here, we demonstrate that PomX consists of two functionally distinct domains and has three functions. The N-terminal domain stimulates ATPase activity of the ParA/MinD ATPase PomZ. The C-terminal domain interacts with PomY and forms polymers, which serve as a scaffold for PomX/Y/Z complex formation. Moreover, the PomX/PomZ interaction is important for fission of the PomX/Y/Z complex. These observations together with previous work support that the architecturally diverse ATPase activating proteins of ParA/MinD ATPases are highly modular and use the same mechanism to activate their cognate ATPase via a short positively charged N-terminal extension.
In addition to restrictions in training companies, vocational schools were also closed due to the coronavirus pandemic in Germany. After the unexpected first lockdown, it was the challenge of all ...those involved to draw lessons from the emergent weaknesses in the system and to prepare for further school closures. These preparations primarily involved shifting to digital learning platforms. This article uses a simple and easy to understand research design and focuses from a practical point of view on the results of a quantitative online survey conducted by the University of Applied Labour Studies Mannheim among 143 apprentices in southern Germany on the differences between the first and second school closures with regard to live communication with teachers, attention to apprentice concerns by the vocational school, access to digital devices, and the use of these devices. The results of the survey show that, according to the apprentices’ assessments, the vocational schools were able to improve live communication as well as better attend to the apprentices’ concerns between lockdowns. In addition, the apprentices were able to improve their own digital devices and competencies and, to a large extent, make up for deficits. They were better able to use digital devices and software during the second school closure compared to the first. Gender differences were observed. However, despite significant improvements, there is still a need to modernize and innovate, which should be considered in future digital developments at schools.
In recent years, the importance of vitamin A in adipose tissue biology, obesity and type II diabetes has become apparent. This review focuses on recent developments within the area of vitamin A and ...adipose tissue biology. Adipose tissue has an active vitamin A metabolism as it not only stores vitamin A but retinol is also converted to its active metabolite retinoic acid. Several mouse models point to a relationship between vitamin A metabolism and the development of adiposity. Similarly, in vitro studies provide new molecular mechanisms for the function of different forms of vitamin A and retinol- or retinoic acid-binding proteins in adipose tissue.
With the global spread of the 2009 pandemic H1N1 (pH1N1) influenza virus, there are increasing worries about evolution through antigenic drift. One way previous seasonal H1N1 and H3N2 influenza ...strains have evolved over time is by acquiring additional glycosylations in the globular head of their hemagglutinin (HA) proteins; these glycosylations have been believed to shield antigenically relevant regions from antibody immune responses. We added additional HA glycosylation sites to influenza A/Netherlands/602/2009 recombinant (rpH1N1) viruses, reflecting their temporal appearance in previous seasonal H1N1 viruses. Additional glycosylations resulted in substantially attenuated infection in mice and ferrets, whereas deleting HA glycosylation sites from a pre-pandemic virus resulted in increased pathogenicity in mice. We then more directly investigated the interactions of HA glycosylations and antibody responses through mutational analysis. We found that the polyclonal antibody response elicited by wild-type rpH1N1 HA was likely directed against an immunodominant region, which could be shielded by glycosylation at position 144. However, rpH1N1 HA glycosylated at position 144 elicited a broader polyclonal response able to cross-neutralize all wild-type and glycosylation mutant pH1N1 viruses. Moreover, mice infected with a recent seasonal virus in which glycosylation sites were removed elicited antibodies that protected against challenge with the antigenically distant pH1N1 virus. Thus, acquisition of glycosylation sites in the HA of H1N1 human influenza viruses affected not only their pathogenicity and ability to escape from polyclonal antibodies elicited by previous influenza virus strains but also their ability to induce cross-reactive antibodies against drifted antigenic variants.
Although the high costs of implementing personnel development programs in enterprises and increasingly in universities as well are commonly accepted, the scientifically-grounded evaluation of a ...program's effectiveness is often neglected. The aim of this paper was to evaluate a personnel development program for academics at a German university (N=1426). We investigated the program's effectiveness on Kirkpatrick's four levels. We examined short- and long-term effects with a repeated measurements design. In sum, 123 training programs were clustered into 26 primary studies. We conducted t-tests and aggregated the effect sizes (d) using meta-analytical techniques. We found a high short-term effect and a moderate to high long-term effect for the learning level, and a small to moderate long-term effect for the behavior level. Participants' organizational commitment did not increase. Our results have appealing practical implications for university HR managers, trainers, and evaluators.
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BFBNIB, DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Membrane compartmentalization and trafficking are pivotal for eukaryotic life and demand a higher order of coordination. Even in their resting state, most plant cells exhibit a polarized localization ...of membrane compartments, which is redirected when plant cells are attacked by microbes. Repositioning of organelles at pathogen penetration sites has been reported since more than a decade; however, only recently has targeted vesicle trafficking upon biotic stress emerged. It has become evident that vesicle secretion and endocytic pathways are engaged in the plant's immune system to actively defend against potential pathogens. By contrast, invasive pathogens have evolved means to utilize these trafficking pathways for the suppression of plant defenses and to the benefit of microbial proliferation. This review summarizes recent findings of host intracellular endomembrane adaptations in response to pathogens and how pathogens exploit them.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Cell division site positioning is precisely regulated to generate correctly sized and shaped daughters. We uncover the strategy used by the social bacterium Myxococcus xanthus to position the FtsZ ...cytokinetic ring at midcell. PomX, PomY, and the nucleoid-binding ParA/MinD ATPase PomZ self-assemble forming a large nucleoid-associated complex that localizes at the division site before FtsZ to directly guide and stimulate division. PomXYZ localization is generated through self-organized biased random motion on the nucleoid toward midcell and constrained motion at midcell. Experiments and theory show that PomXYZ motion is produced by diffusive PomZ fluxes on the nucleoid into the complex. Flux differences scale with the intracellular asymmetry of the complex and are converted into a local PomZ concentration gradient across the complex with translocation toward the higher PomZ concentration. At midcell, fluxes equalize resulting in constrained motion. Flux-based mechanisms may represent a general paradigm for positioning of macromolecular structures in bacteria.
•PomX, PomY, and the ParA ATPase PomZ stimulate FtsZ-ring formation and positioning•The PomXYZ complex translocates to midcell driven by diffusive PomZ fluxes•Flux imbalances convert intracellular asymmetry of PomXYZ to local PomZ gradient•Translocation bias of PomXYZ scales with intracellular asymmetry of PomXYZ complex
Schumacher et al. find that the PomXYZ complex self-organizes on the bacterial nucleoid and promotes positioning of the cytokinetic ring. Diffusive fluxes of PomZ into the complex scale with intracellular asymmetry and are converted into a local PomZ concentration gradient that promotes biased motion toward and constrained motion at midcell.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The aim of this article was to examine the role of employees' motivational orientation for work-life enrichment (WLE) and conflict (WLC). On the basis of the Work-Home-Resources Theory and Regulatory ...Focus Theory we conducted 2 cross-sectional studies (n1 = 202, n2 = 199). We hypothesized that a promotion orientation (toward personal growth and success) indirectly goes along with higher levels of WLE through work-related stress. We assumed that a prevention orientation (toward the prevention of losses and failure) is indirectly associated with higher levels of WLC through work-related stress. Simple mediation analyses partly supported our hypotheses. Higher levels of promotion focus went along with higher levels of WLE. Higher levels of prevention focus were associated with higher levels of WLC. Although we found an indirect effect of regulatory focus on WLE and WLC through emotional stress, we did not find one for cognitive stress. This project contributes to a deeper understanding of what fosters WLE and WLC and adds a new motivational perspective for work-life research. Our results can also be taken into account in practice for the development of organizational work-life policies or interventions.
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CEKLJ, FFLJ, NUK, ODKLJ, PEFLJ, UPUK
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