Plant cells create highly structured microtubule arrays at the cell cortex without a central organizing center to anchor ends. In vivo imaging of individual microtubules in Arabidopsis plants revealed that new are initiated and exhibit dynamics both Polymerization-biased dynamic instability one end slow depolymerization other result sustained migration across by hybrid treadmilling mechanism. This motility causes widespread repositioning contributes changes array organization through...

Summary Establishment of the Rhizobium –legume symbiosis depends on a molecular dialogue, in which rhizobial nodulation (Nod) factors act as symbiotic signals, playing key role control specificity infection and nodule formation. Using nodulation‐defective (Nod − ) mutants Medicago truncatula to study mechanisms controlling Nod factor perception signalling, we have previously identified five genes that components factor‐activated signal transduction pathway. Characterisation new M. mutant led...

Localization of dynein-green fluorescent protein (GFP) to cytoplasmic microtubules allowed us obtain one the first views dynamic properties astral in live budding yeast. Several novel aspects microtubule function were revealed by time-lapse, three-dimensional fluorescence microscopy. Astral microtubules, about four six number for each pole, exhibited asynchronous instability throughout cell cycle, growing at approximately 0.3-1.5 micron/min toward surface then switching shortening similar...

Bacterial flagella are highly conserved molecular machines that have been extensively studied for assembly, function and gene regulation. Less is how why bacteria differ based on the number arrangement of they synthesize. Here we explore cell biology peritrichous in model bacterium Bacillus subtilis by fluorescently labelling flagellar basal bodies, hooks filaments. We find average B. assembles approximately 26 bodies show body controlled SwrA. Basal assembled rapidly (< 5 min) but assembly...

Significance This study answers two long-standing questions about FtsZ dynamics and its relationship to septal peptidoglycan (PG) synthesis in Streptococcus pneumoniae . In previous models, concertedly moves from midcell septa MapZ rings that have reached the equators of daughter cells. Instead, results presented here show FtsZ, FtsA, EzrA filaments/bundles move continuously out early as part rings. addition, this establishes movement bPBP2x:FtsW complexes PG depends on likely mirrors new is...

Bacterial cell shapes are manifestations of programs carried out by multi-protein machines that synthesize and remodel the resilient peptidoglycan (PG) mesh other polymers surrounding cells. GpsB protein is conserved in low-GC Gram-positive bacteria not essential rod-shaped Bacillus subtilis, where it plays a role shuttling penicillin-binding proteins (PBPs) between septal side-wall sites PG synthesis. In contrast, we report here ellipsoid-shaped, ovococcal Streptococcus pneumoniae...

Abstract Modulation of intracellular calcium levels plays a key role in the transduction many biological signals. Here, we characterize early responses wild-type and mutant Medicago truncatula plants to nodulation factors produced by bacterial symbiont Sinorhizobium meliloti using dual-dye ratiometric imaging technique. When presented with 1 nm Nod factor, root hair cells exhibited only previously described spiking response initiating 10 min after application. factor (10 nm) elicited an...

Hydrogen peroxide (H(2)O(2)) efflux was measured from Medicago truncatula root segments exposed to purified Nod factor and poly-GalUA (PGA) heptamers. factor, at concentrations > 100 pM, reduced H(2)O(2) rates 60% of baseline levels beginning 20 30 min after exposure, whereas the PGA elicitor, 75 nM, caused a rapid increase in >200% rates. Pretreatment plants with alters effect by limiting maximum rate 125% that observed for untreated plants. Two factor-related compounds showed no ability...

As the legume-rhizobia symbiosis is established, plant recognizes bacterial-signaling molecules, Nod factors (NFs), and initiates transcriptional developmental changes within root to allow bacterial invasion construction of a novel organ, nodule. Plant mutants defective in nodule initiation (Nod - ) are thought have defects NF-signal transduction. However, it unknown whether WT plants respond NF-independent bacterial-derived signals or show global symbiosis-associated gene expression. To...

Abstract The Arabidopsis thaliana MAP65-1 and MAP65-2 genes are members of the larger eukaryotic MAP65/ASE1/PRC gene family microtubule-associated proteins. We created fluorescent protein fusions driven by native promoters that colocalized to a subset interphase microtubule bundles in all epidermal hypocotyl cells. labeling was highly dynamic within bundles, showing episodes linear extension retraction coincident with growth shortening. Dynamic colocalization MAP65-1/2 polymerizing...

Summary The relative localization patterns of class B penicillin‐binding proteins Pbp2x and Pbp2b were used as positional indicators septal peripheral (side‐wall‐like) peptidoglycan ( PG ) synthesis, respectively, in the mid‐cell regions S treptococcus pneumoniae cells at different stages division. We confirm that are essential strain D 39 genetic background, which differs from laboratory strains. show , like A Pbp1a follows a pattern than FtsZ remains division septa after reappears equators...

Abstract The acentriolar cortical microtubule arrays in dark-grown hypocotyl cells organize into a transverse coaligned pattern that is critical for axial plant growth. In light-grown Arabidopsis thaliana seedlings, the array on outer (periclinal) cell face creates variety of patterns with significant bias (&amp;gt;3:1) microtubules polymerizing edge-ward and side (anticlinal) faces cell. To study mechanisms required creating coalignment, we developed dual-hormone protocol synchronously...

ABSTRACT In this study, we investigate the role of polar secretion and resulting asymmetry in cell wall establishing polarity Fucus zygotes. We have utilized brefeldin-A to selectively interrupt Golgi-derived material into as assayed by toluidine blue O staining sulfated fucoidin. show that is targeted a cortical site zygote identified localization actin filaments dihydropyridine receptors. The deposition at target temporally coincident with required for axis fixation. propose local...

Localization of mRNA is a well-described mechanism to account for the asymmetric distribution proteins in polarized somatic cells and embryos animals. In zygotes brown alga Fucus, F-actin localized at site polar growth accumulates cell plates first two divisions embryo. We used nonradioactive, whole-mount situ hybridization protocol show pattern actin localization. Until division, localization identical that total poly(A)+ RNA, is, symmetrical zygote followed by an actin-dependent...

The bipolar budding pattern of a /α Saccharomyces cerevisiae cells appears to depend on persistent spatial markers in the cell cortex at two poles cell. Previous analysis mutants with specific defects identifiedBUD8 and BUD9 as potentially encoding components distal proximal birth scar, respectively. Further genetic reported here supports this hypothesis. Mutants deleted for BUD8 orBUD9 grow normally but bud exclusively from poles, respectively, double-mutant phenotype suggests that pathway...

Flowering plants evolved an array of environmental sensors important for guiding adaptive morphological responses. The response to elevated ambient temperature involves the thermo-conversion light-sensing protein, PHYTOCHROME B (PhyB), leading activation nuclear transcription factor, INTERACTING FACTOR 4 (PIF4). Here we employ and light treatments dissect role WAVE DAMPENED2-LIKE (WDL4), a microtubule associated cytoplasmic in modulating this signaling pathway. WDL4 mutant ( wdl4-3 )...

Abstract Fluorescent microspheres were used as material markers to investigate the relative rates of cell surface expansion at growing tips Medicago truncatula root hairs. From analysis tip shape and microsphere movements, we propose three characteristic zones in The center apical dome is an area 1- 2-μm diameter with relatively constant curvature high growth rate. Distal apex a more rapidly expanding region 1 2 μm width exhibiting surges off-axis growth. This middle forms annulus maximum...

Abstract Wall expansion in tip-growing cells shows variations according to position and direction. In Medicago truncatula root hairs, wall exhibits a strong meridional gradient with maximum near the pole of cell. Root hair also show striking anisotropy, i.e. over most dome surface rate circumferential exceeds expansion. Concomitant measurements rates stresses reveal that extensibility cell must vary abruptly along meridian maintain To determine mechanical basis we compared patterns predicted...