Monnina (Polygalaceae), a New World monophyletic genus full of contrasts.

Endemic to the Neotropics, Monnina is the second largest genus of Polygalaceae, yet little is known about its phylogenetic history, biogeography, and morphological character evolution. To address these knowledge gaps, we conducted Bayesian and maximum likelihood (ML) analyses of nuclear ITS and plastid trnL–F regions to test the monophyly of Monnina s.l. We used this phylogenetic framework to (i) infer divergence time estimates of lineages within the genus and reconstruct their historical biogeography; (ii) reconstruct the evolution of morphological characters of putative ecological and evolutionary importance in Monnina; and (iii) test for correlations between our phylogenetic hypothesis and environmental data. Our results reveal that Monnina is monophyletic with an indehiscent, 1–2-seeded fruit as a synapomorphy for the genus. We identify six clades within Monnina based on our combined phylogenetic results: Clades A, B, and D are primarily distributed in southern and eastern South America, Clades C and E are primarily Central Andean, and Clade F is chiefly distributed in the Northern Andes and Central America. The ancestor of the Monnina stem lineage dispersed from Australia/Africa to South America during the late Eocene to early Oligocene. The divergences of major lineages within the genus began in the early Miocene. We inferred the most recent common ancestor of Monnina to be an herbaceous plant with one-seeded samaroid fruits. The origins of fleshy fruits and shrubby habits are phylogenetically correlated within Monnina, and their concerted convergent evolution may have promoted increased net diversification rates in the two most species-rich subclades of the genus

Generation of aggregation prone N-terminally truncated amyloid β peptides by meprin β depends on the sequence specificity at the cleavage site

BACKGROUND: The metalloprotease meprin β cleaves the Alzheimer's Disease (AD) relevant amyloid precursor protein (APP) as a β-secretase reminiscent of BACE-1, however, predominantly generating N-terminally truncated Aβ2-x variants. RESULTS: Herein, we observed increased endogenous sAPPα levels in the brains of meprin β knock-out (ko) mice compared to wild-type controls. We further analyzed the cellular interaction of APP and meprin β and found that cleavage of APP by meprin β occurs prior to endocytosis. The N-terminally truncated Aβ2-40 variant shows increased aggregation propensity compared to Aβ1-40 and acts even as a seed for Aβ1-40 aggregation. Additionally, we observed that different APP mutants affect the catalytic properties of meprin β and that, interestingly, meprin β is unable to generate N-terminally truncated Aβ peptides from Swedish mutant APP (APPswe). CONCLUSION: Concluding, we propose that meprin β may be involved in the generation of N-terminally truncated Aβ2-x peptides of APP, but acts independently from BACE-1

Conveyed leader PsyCap predicting leader effectiveness through positive energizing

Whereas past research on psychological capital (PsyCap) has tended to focus on how one's self-attributed PsyCap affects one's work behaviors, we extend this literature by examining the concept of conveyed PsyCap and its downstream consequences, above and beyond the influence of self-attributed PsyCap. Drawing from the emotions-as-social-information model, we tested a model of conveyed leader PsyCap predicting leader effectiveness through team positive energizing. A laboratory experiment and a multisource study provided support for our hypotheses. We furthermore found that a leader's within-team consistency in conveyed PsyCap moderates these effects, such that leaders who are more consistent in conveyed PsyCap are rated by followers as better leaders, via the mediating effect of team positive energizing. A post hoc analysis further suggests that conveyed PsyCap is more consistent when conveyed PsyCap is congruent with self-attributed PsyCap. Our work contributes to a better understanding of the underlying mechanisms that make leaders with greater conveyed PsyCap more effective and advances the conceptualization and measurement of PsyCap.info:eu-repo/semantics/acceptedVersio