The co-chaperone p23 controls root development through the modulation of auxin distribution in the Arabidopsis root meristem

p23 co-chaperones play a key role in the root meristem maintenance via regulation of auxin signalling and the consequent balance between cell differentiation and division rate at the transition zon

The Mitochondrial Protein Whirly2 Regulates Seed Germination and Early Stages of Growth in Arabidopsis Thaliana

Variations in amount and structural integrity of organellar DNA are tightly regulated by nuclear-organelle cross-talk. Whirly proteins are DNA binding proteins that were shown to play a role in organellar DNA maintenance and organization [Marechal et al. 2008; Cappadocia et al 2010]. Arabidopsis thaliana has three Whirly proteins with different subcellular localization: Whirly1 and Whirly3 are targeted to chloroplasts, while Whirly2 is targeted to mitochondria [Krause et al. 2005]. WHIRLY2 gene expression is related to early plant development, being expressed in imbibed seeds, shoot apex and roots of young seedlings. A T-DNA insertional mutant for the WHIRLY2 gene shows an obvious phenotype on seeds, germination and early stages of plant growth. At subcellular level Whirly2 regulates mitochondria morphology, dynamics and functionality of the electron transport chain. Transmitted electron microscopy (TEM) revealed that Whirly2 is a major mitochondrial nucleoids organizer, and it influences both mtDNA and ptDNA copy number. Moreover, our results suggest a coordination of WHIRLY genes that controls expression of target genes of organellar signals upon development and stress conditions.Le variazioni della quantità e dell'integrità strutturale del DNA degli organelli sono strettamente regolate dal cross-talk tra i vari compartimenti subcellulari. Le proteine Whirly sono in grado di legare il DNA ed è stato dimostrato come esse abbiano un ruolo chiave nel mantenimento e nell’organizzazione strutturale del DNA degli organelli [Marechal et al. 2008; Cappadocia et al 2010]. Arabidopsis thaliana possiede tre proteine Whirly con diversa localizzazione subcellulare: Whirly1 e Whirly3 localizzano nei cloroplasti, mentre Whirly2 localizza a livello mitocondriale [Krause et al. 2005]. È stato osservato come l’espressione del gene WHIRLY2 sia modulata durante la crescita della pianta. In particolare, WHIRLY2 è maggiormente espresso nei semi imbibiti e nei meristemi apicali e radicali. Il mutante inserzionale per il gene WHIRLY2 presenta infatti, un chiaro fenotipo nello sviluppo del seme e nella germinazione. A livello subcellulare, Whirly2 regola la morfologia, la dinamica e la funzionalità mitocondriale. Inoltre, è stato rilevato come Whirly2 sia indispensabile nel mantenimento strutturale dei nucleoidi mitocondriali e del contenuto DNA negli organelli. In aggiunta, i nostri risultati suggeriscono un coordinamento nell’espressione dei geni WHIRLY con lo scopo di mantenere un’adeguata omeostasi cellulare sia durante lo sviluppo che in condizioni di stress

The Mitochondrial Protein Whirly2 Regulates Seed Germination and Early Stages of Growth in Arabidopsis Thaliana

Variations in amount and structural integrity of organellar DNA are tightly regulated by nuclear-organelle cross-talk. Whirly proteins are DNA binding proteins that were shown to play a role in organellar DNA maintenance and organization [Marechal et al. 2008; Cappadocia et al 2010]. Arabidopsis thaliana has three Whirly proteins with different subcellular localization: Whirly1 and Whirly3 are targeted to chloroplasts, while Whirly2 is targeted to mitochondria [Krause et al. 2005]. WHIRLY2 gene expression is related to early plant development, being expressed in imbibed seeds, shoot apex and roots of young seedlings. A T-DNA insertional mutant for the WHIRLY2 gene shows an obvious phenotype on seeds, germination and early stages of plant growth. At subcellular level Whirly2 regulates mitochondria morphology, dynamics and functionality of the electron transport chain. Transmitted electron microscopy (TEM) revealed that Whirly2 is a major mitochondrial nucleoids organizer, and it influences both mtDNA and ptDNA copy number. Moreover, our results suggest a coordination of WHIRLY genes that controls expression of target genes of organellar signals upon development and stress conditions

Systemic Calcium Wave Propagation in Physcomitrella patens

The adaptation to dehydration and rehydration cycles represents a key step in the evolution of photosynthetic organisms and requires the development of mechanisms by which to sense external stimuli and translate them into signaling components. In this study, we used genetically encoded fluorescent sensors to detect specific transient increases in the Ca2+ concentration in the moss Physcomitrella patens upon dehydration and rehydration treatment. Observation of the entire plant in a single time-series acquisition revealed that various cell types exhibited different sensitivities to osmotic stress and that Ca2+ waves originated from the basal part of the gametophore and were directionally propagated towards the top of the plant. Under similar conditions, the vascular plant Arabidopsis thaliana exhibited Ca2+ waves that propagated at a higher speed than those of P. patens. Our results suggest that systemic Ca2+ propagation occurs in plants even in the absence of vascular tissue, even though the rates can be different

Effects of prolonged flushing interval in totally implantable venous access devices (TIVADs)

Totally implantable venous access device (TIVAD) lumen occlusion is a long-term complication of central venous catheters, associated with risks of infection, therapy interruptions and increased healthcare costs. The role of flushing and locking in maintaining TIVAD patency is paramount. Most flushing protocols are based on manufacturers' recommendations, which indicate that 4 weeks is the safest interval between two consecutive flushing procedures during periods when TIVADs are not in use. Conversely, results of several studies suggest that extended flushing intervals (FIs) do not increase the rate of obstructive or infective complications. The study aimed to describe the effects of prolonged FIs in a cohort of 317 patients with cancer. The authors found no significant difference in terms of TIVAD problems between long (>45 days) and short ( 6445 days) FI groups, which raises questions over the validity of current practice