Structural and mechanistic insights into the complexes formed by Wolbachia cytoplasmic incompatibility factors

Wolbachia bacteria, inherited through the female germ line, infect a large fraction of arthropod species. Many Wolbachia strains manipulate host reproduction, most commonly through cytoplasmic incompatibility (CI). CI, a conditional male sterility, results when Wolbachia-infected male insects mate with uninfected females; viability is restored if the female is similarly infected (called “rescue”). CI is used to help control mosquito-borne viruses such as dengue and Zika, but its mechanisms remain unknown. The coexpressed CI factors CifA and CifB form stable complexes in vitro, but the timing and function of this interaction in the insect are unresolved. CifA expression in the female germ line is sufficient for rescue. We report high-resolution structures of a CI-factor complex, CinA-CinB, which utilizes a unique binding mode between the CinA rescue factor and the CinB nuclease; the structures were validated by biochemical and yeast growth analyses. Importantly, transgenic expression in Drosophila of a nonbinding CinA mutant, designed based on the CinA-CinB structure, suggests CinA expressed in females must bind CinB imported by sperm in order to rescue embryonic viability. Binding between cognate factors is conserved in an enzymatically distinct CI system, CidA-CidB, suggesting universal features in Wolbachia CI induction and rescue.

Identification of Multisystemic Therapy (MST) Subgroups with Distinct Trajectories on Ultimate Outcomes in Norway

The effect of Multisystemic Therapy (MST) treatment for serious behavior problems among adolescents has been established through multiple studies. However, variations across individuals should also be examined to better understand how MST works or for whom. In this study, we explored and identified subgroups of youth with serious problems in Norway regarding their responses to MST in terms of ultimate MST outcomes (e.g., living at home, abstaining from violence) over time. We further explored whether immigrant background, in addition to gender and age of the youth at intake, predicted belonging to the subgroups. Data came from 1674 adolescents (MeanAge = 14.55, SDAge = 1.58; 60.7% boys) and their families referred to MST treatment by the municipal Child Welfare Services for serious and persistent antisocial behavior. The outcomes were assessed at five time-points from intake to 18-months after discharge for youth and families who completed the treatment. Latent class growth analyses revealed heterogeneous trajectories regarding youths’ responses to MST. Results indicated a high and sustained degree of improvement across the ultimate outcomes for the vast majority of the youths. However, there was still variation in the groups, with improvement and deterioration trajectories for various outcomes. Most of these trajectories were predicted by gender and youth’s age at intake, but not by immigrant status. Not every youth-at-risk responds similarly to MST, and more studies examining heterogeneity will help us to identify factors to be targeted to better tailor the MST interventions for youth with serious problems.

Police Productivity and Performance Over the Career Course: A Latent Class Growth Analysis of the First 10 Years of Law Enforcement

The present research investigates the productivity and performance of a large sample of police officers, beginning in the police academy and through their first 10 years of policing. Using longitudinal data and latent class growth analyses, we examine measures of productivity and performance over this time. Findings indicate that officers’ academy performance did not influence officer trajectories, but selected demographic variables were significantly related to performance across the career course. Among these, female and non-White officers were consistently rated lower in their performance evaluations. Overall, results suggest that factors predicting productivity and performance are dynamic, and there is no single combination of characteristics that predicts who will be a “good” officer.

Latent Class Growth Analysis and Growth Mixture Modeling using R: A tutorial for two R-packages and a comparison with Mplus.

Latent Class Growth Analyses (LCGA) and Growth Mixture Modeling (GMM) analyses are used to explain between-subject heterogeneity in growth on an outcome, by identifying latent classes with different growth trajectories. Dedicated software packages are available to estimate these models, with Mplus (Muthén & Muthén, 2019) being widely used . Although this and other available commercial software packages are of good quality, very flexible and rich in options, they can be costly and fit poorly into the analytical workflow of researchers that increasingly depend on the open-source R-platform. Interestingly, although plenty of R-packages to conduct mixture analyses are available, there is little documentation on how to conduct LCGA/GMM in R. Therefore, the current paper aims to provide applied researchers with a tutorial and coding examples for conducting LCGA and GMM in R. Furthermore, it will be evaluated how results obtained with R and the modeling approaches (e.g., default settings, model configuration) of the used R-packages compare to each other and to Mplus.

Designing an early failure indicator channel for an in-tank hydrogen valve via a fatigue-based approach

This study introduced a fatigue-based approach to design and implement an indicator channel into an in-tank hydrogen valve. It was aimed at providing a mean to point out multiple early valve's damages. To achieve the goal, the study was proposed to handle via three main phases. They included (i) the risk point determinations, (ii) the new valve design and the crack nucleation life estimations, as well as (iii) the simplified crack growth analyses. The obtained results firstly highlighted the construction of the test channel (TC), whose branches were located close to the predicted damage's sites. The damages could be identified either when a crack reaches the TC (then forms a leakage) or indirectly via the crack propagations’ correlation. The results also pointed out that the TC-implemented valve could perform as similarly as the non-TC one in the non-treated condition. More importantly, this new structure was proved to have a capacity of satisfying the required minimal life of 1.5E5 cycles, depending on the combined uses of the specific material and the pre-treatment, among those considered. In addition, the results emphasized the complexity of the TC that could not be formed by the traditional manufacturing process. Hence, direct metal laser sintering was proposed for the associated prototype and the final TC was issued based on the fundamental requirements of the technique. Finally, it was suggested that practical experiments should essentially be carried out to yield more evidence to support the demonstrated results.

Waterlogging effects upon the phenological phases of common bean cultivar BRSMG-Uai

ABSTRACT Common bean (Phaseolus vulgaris L.) is an important source of protein and carbohydrates, besides being rich in several mineral nutrients. In a flooding situation, the low availability of oxygen may result in hypoxia or anoxia condition. Therefore, this study aimed to evaluate the responses of the common bean cultivar BRSMG-Uai subjected to hypoxia in different phenological phases, analyzing its responses in terms of growth, productivity, carbon and nitrogen metabolism. Thus, seeds of common beans were germinated and when the seedling reached growth stage V1, they were transferred to plastic boxes containing 40L of nutritive solution with steady aeration. Distinct series of plants were exposed to air-restriction on their roots for nine days, in three different phenological phases V3/V4, R6 and R7. Samples were collected for biochemical and growth analyses in a completely random design (n=6). The plants subjected to low availability of oxygen presented a reduction in bean number, displaying the greatest loss in productivity in V3/V4, conferring the highest sensitivity to hypoxia in this phase. On the other hand, there was an increase in sugar concentration in leaves, and it was also possible to observe an increase in hydrogen peroxide in leaves and roots, concomitant with a decrease in superoxide dismutase activity in all phenological phases. There was also an increase in ascorbate peroxidase activity in roots in R6, as well as in nitrate reductase activity. We conclude that the cultivar BRSMG-Uai presents sensitivity to low oxygen availability, and the phenological phaseV3/V4 is the most critical for it.