Emergence of tissue polarization from synergy of intracellular and extracellular auxin signaling

Here, we provide a novel mechanistic framework for cell polarization during auxin-driven plant development that combines intracellular auxin signaling for regulation of expression of PINFORMED (PIN) auxin efflux transporters and the theoretical assumption of extracellular auxin signaling for regulation of PIN subcellular dynamics.The competitive utilization of auxin signaling component in the apoplast might account for the elusive mechanism for cell-to-cell communication for tissue polarization.Computer model simulations faithfully and robustly recapitulate experimentally observed patterns of tissue polarity and asymmetric auxin distribution during formation and regeneration of vascular systems, and during the competitive regulation of shoot branching by apical dominance.Our model generated new predictions that could be experimentally validated, highlighting a mechanistically conceivable explanation for the PIN polarization and canalization of the auxin flow in plants

Strigolactones inhibit auxin feedback on PIN-dependent auxin transport canalization

Directional transport of the phytohormone auxin is a versatile, plant-specific mechanism regulating many aspects of plant development. The recently identified plant hormones, strigolactones (SLs), are implicated in many plant traits; among others, they modify the phenotypic output of PIN-FORMED (PIN) auxin transporters for fine-tuning of growth and developmental responses. Here, we show in pea and Arabidopsis that SLs target processes dependent on the canalization of auxin flow, which involves auxin feedback on PIN subcellular distribution. D14 receptor- and MAX2 F-box-mediated SL signaling inhibits the formation of auxin-conducting channels after wounding or from artificial auxin sources, during vasculature de novo formation and regeneration. At the cellular level, SLs interfere with auxin effects on PIN polar targeting, constitutive PIN trafficking as well as clathrin-mediated endocytosis. Our results identify a non-transcriptional mechanism of SL action, uncoupling auxin feedback on PIN polarity and trafficking, thereby regulating vascular tissue formation and regeneration

The impact of post-procedural complications on reimbursement, length of stay and mechanical ventilation among patients undergoing transcatheter aortic valve implantation in Germany

BACKGROUND: The impact of various post-procedural complications after transcatheter aortic valve implantation (TAVI) on resource use and their consequences in the German reimbursement system has still not been properly quantified. METHODS: In a retrospective observational study, we use data from the German DRG statistic on patient characteristics and in-hospital outcomes of all isolated TAVI procedures in 2013 (N = 9147). The impact of post-procedural complications on reimbursement, length of stay and mechanical ventilation was analyzed using both unadjusted and risk-adjusted linear and logistic regression analyses. RESULTS: A total of 235 (2.57%) strokes, 583 (6.37%) bleeding events, 474 (5.18%) cases of acute kidney injury and 1428 (15.61%) pacemaker implantations were documented. The predicted reimbursement of an uncomplicated TAVI procedure was €33,272, and bleeding events were associated with highest additional reimbursement (€12,839, p 48 h: OR 6.93, p 48 h: OR 5.73, p < 0.001). Pacemaker implantations, in contrast, were associated with comparably small increases in reimbursement (€662, p = 0.006) and length of stay (3.54 days, p = 0.006) and no impaired likelihood of mechanical ventilation more than 48 h (OR 1.22, p = 0.156). Interestingly, these complication-related consequences remain mostly unchanged after baseline risk-adjustment. CONCLUSIONS: Post procedural complications such as bleeding events, acute kidney injuries and strokes are associated with increased resource use and substantial amounts of additional reimbursement in Germany, which has important implications for decision making outside of the usual clinical sphere

Roots of Ergativity in Africa (and Beyond)

In the literature, it is often assumed that ergative constructions originate in passive constructions. The present contribution explores the likelihood of such a passive-to-ergative analysis for one language (Tima, Niger-Congo, Sudan), showing that this analysis cannot be substantiated and suggesting an origin in active constructions instead. This study is situated in its areal context (outlining similarities to split case marking systems across the region, especially in the Southern branch of Eastern Sudanic) and against the background of discussions in the Indo-Iranian family (from where the passive-to-ergative hypothesis presumably spread)