Cell Edges Accumulate Gamma Tubulin Complex Components and Nucleate Microtubules following Cytokinesis in Arabidopsis thaliana

Microtubules emanate from distinct organizing centers in fungal and animal cells. In plant cells, by contrast, microtubules initiate from dispersed sites in the cell cortex, where they then self-organize into parallel arrays. Previous ultrastructural evidence suggested that cell edges participate in microtubule nucleation but so far there has been no direct evidence for this. Here we use live imaging to show that components of the gamma tubulin nucleation complex (GCP2 and GCP3) localize at distinct sites along the outer periclinal edge of newly formed crosswalls, and that microtubules grow predominantly away from these edges. These data confirm a role for cell edges in microtubule nucleation, and suggest that an asymmetric distribution of microtubule nucleation factors contributes to cortical microtubule organization in plants, in a manner more similar to other kingdoms than previously thought

Arabidopsis BTB/POZ protein-dependent PENETRATION3 trafficking and disease susceptibility

The outermost cell layer of plant roots (epidermis) constantly encounters environmental challenges. The epidermal outer plasma membrane domain harbours the PENETRATION3 (PEN3)/ABCG36/PDR8 ATP-binding cassette transporter that confers non-host resistance to several pathogens. Here, we show that the Arabidopsis ENDOPLASMIC RETICULUM-ARRESTED PEN3 (EAP3) BTB/POZ-domain protein specifically mediates PEN3 exit from the endoplasmic reticulum and confers resistance to a root-penetrating fungus, providing prime evidence for BTB/POZ- domain protein-dependent membrane trafficking underlying disease resistance.The PENETRATION3 (PEN3/ABCG36/PDR8) ATP-binding cassette transporter of Arabidopsis thaliana is a crucial component of preinvasive defence against some fungal and bacterial non-host pathogens entering by direct penetration1,2,3,4. In above-ground organs, PEN3 is recruited to sites of pathogen attack at the cell surface3,4. In seedling roots, PEN3 polarly localizes to the epidermal outer membrane domain in the absence of pathogens5,6. Root epidermal cells display four major polar plasma membrane domains: the outer domain facing the environment, the inner domain oriented towards the cortical cell layer, the shootward-oriented, apical, and the root tip-oriented, basal, domain6. Proteins in the outer domain that function in regulating the transport of inorganic compounds include, for example, the NIP5;1 boric acid uptake channel7. Factors required for PEN3 and NIP5;1 trafficking from the trans-Golgi network to the outer domain have been identified8,9,10, and exocyst complex components promote polar tethering of several outer domain proteins9,11. However, factors that specifically mediate trafficking of polar outer membrane cargos involved in responses to root-penetrating pathogens remain to be discovered.In a genetic screen for mislocalization of PEN3 fused to green-fluorescent protein (PEN3- GFP) in the root epidermis of seedlings9, we recovered one recessive mutant in which PEN3-GFP localized to a cytoplasmic structure resembling the endoplasmic reticulum (ER) (Fig. 1a–d). This er-arrested pen3-1 (eap3-1) mutation indistinguishably affected localization of PEN3-GFP from that of PEN3-mCherry (Supplementary Fig. 1a,b), which colocalized with the ER-intrinsic chaperone BIP in the eap3-1 mutant (Supplementary Fig. 1c,d), corroborating an ER arrest of PEN3

Технический университет как субъект инновационной инфраструктуры

Материалы ХI Международной науч.-техн. конф. студентов, магистрантов и аспирантов [28-29 апреля 2011 г., г. Гомель]. - Гомель, 2011

Oscillating rolling element bearings: A review of tribotesting and analysis approaches

Rolling element bearings, when subjected to small oscillating movements or vibrations, run the risk of being damaged by mechanisms such as Standstill Marks and False Brinelling. Damages resulting from these phenomena can decrease bearing fatigue life and increase wear-induced friction torque. These failures do not correlate well with standard life estimation approaches. Experimental studies play a crucial role in gaining knowledge in this area. The review integrates knowledge from experiments ranging from single contacts to laboratory and full-scale bearings in wind power and aerospace applications. The generalization is achieved using a non-dimensional amplitude parameter that relates rolling element travel during an oscillation to the Hertzian contact size. The review encompasses testing methods, procedures, reporting practices, result scaling, and application-specific considerations

Functional characterization of the KNOLLE-interacting t-SNARE AtSNAP33 and its role in plant cytokinesis

Cytokinesis requires membrane fusion during cleavage-furrow ingression in animals and cell plate formation in plants. In Arabidopsis, the Sec1 homologue KEULE (KEU) and the cytokinesis-specific syntaxin KNOLLE (KN) cooperate to promote vesicle fusion in the cell division plane. Here, we characterize AtSNAP33, an Arabidopsis homologue of the t-SNARE SNAP25, that was identified as a KN interactor in a yeast two-hybrid screen. AtSNAP33 is a ubiquitously expressed membrane-associated protein that accumulated at the plasma membrane and during cell division colocalized with KN at the forming cell plate. A T-DNA insertion in the AtSNAP33 gene caused loss of AtSNAP33 function, resulting in a lethal dwarf phenotype. atsnap33 plantlets gradually developed large necrotic lesions on cotyledons and rosette leaves, resembling pathogen-induced cellular responses, and eventually died before flowering. In addition, mutant seedlings displayed cytokinetic defects, and atsnap33 in combination with the cytokinesis mutant keu was embryo lethal. Analysis of the Arabidopsis genome revealed two further SNAP25-like proteins that also interacted with KN in the yeast two-hybrid assay. Our results suggest that AtSNAP33, the first SNAP25 homologue characterized in plants, is involved in diverse membrane fusion processes, including cell plate formation, and that AtSNAP33 function in cytokinesis may be replaced partially by other SNAP25 homologues

Peroxidase Profiling Reveals Genetic Linkage between Peroxidase Gene Clusters and Basal Host and Non-Host Resistance to Rusts and Mildew in Barley

Background: Higher plants possess a large multigene family encoding secreted class III peroxidase (Prx) proteins. Peroxidases appear to be associated with plant disease resistance based on observations of induction during disease challenge and the presence or absence of isozymes in resistant vs susceptible varieties. Despite these associations, there is no evidence that allelic variation of peroxidases directly determines levels of disease resistance. Methodology/Principal Findings: The current study introduces a new strategy called Prx-Profiling. We showed that with this strategy a large number of peroxidase genes can be mapped on the barley genome. In order to obtain an estimate of the total number of Prx clusters we followed a re-sampling procedure, which indicated that the barley genome contains about 40 peroxidase gene clusters. We examined the association between the Prxs mapped and the QTLs for resistance of barley to homologous and heterologous rusts, and to the barley powdery mildew fungus. We report that 61 % of the QTLs for partial resistance to P. hordei, 61 % of the QTLs for resistance to B. graminis and 47 % of the QTLs for non-host resistance to other Puccinia species co-localize with Prx based markers. Conclusions/Significance: We conclude that Prx-Profiling was effective in finding the genetic location of Prx genes on the barley genome. The finding that QTLs for basal resistance to rusts and powdery mildew fungi tend to co-locate with Prx clusters provides a base for exploring the functional role of Prx-related genes in determining natural differences in levels o

High lipid order of Arabidopsis cell‐plate membranes mediated by sterol and DYNAMIN‐RELATED PROTEIN1A function

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/109568/1/tpj12674.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/109568/2/tpj12674-sup-0002-FigS2.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/109568/3/tpj12674-sup-0001-FigS1.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/109568/4/tpj12674-sup-0003-FigS3.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/109568/5/tpj12674-sup-0004-FigS4.pd

Endocytosis restricts Arabidopsis KNOLLE syntaxin to the cell division plane during late cytokinesis

Cytokinesis represents the final stage of eukaryotic cell division during which the cytoplasm becomes partitioned between daughter cells. The process differs to some extent between animal and plant cells, but proteins of the syntaxin family mediate membrane fusion in the plane of cell division in diverse organisms. How syntaxin localization is kept in check remains elusive. Here, we report that localization of the Arabidopsis KNOLLE syntaxin in the plane of cell division is maintained by sterol-dependent endocytosis involving a clathrin- and DYNAMIN-RELATED PROTEIN1A-dependent mechanism. On genetic or pharmacological interference with endocytosis, KNOLLE mis-localizes to lateral plasma membranes after cell-plate fusion. Fluorescence-loss-in-photo-bleaching and fluorescence-recovery-after-photo-bleaching experiments reveal lateral diffusion of GFP-KNOLLE from the plane of division to lateral membranes. In an endocytosis-defective sterol biosynthesis mutant displaying lateral KNOLLE diffusion, KNOLLE secretory trafficking remains unaffected. Thus, restriction of lateral diffusion by endocytosis may serve to maintain specificity of syntaxin localization during late cytokinesis

Rino FISICHELLA, La fede come risposta di senso. Abbandonarsi al mistero, Ed. Paoline («Diaconia alla verità», 2), Milano 2005, 175 pp., 12 x 21, ISBN 88-315-2795-9. [RESEÑA]

S (D). (E) Quantification of the number of bulged and non-bulged epidermal cells in the trichoblast or atrichoblast positions of wild-type, and mutants. Error bars show sd. Bar = 100 μm A, B; 50 μm, C, D.<p><b>Copyright information:</b></p><p>Taken from "Insight into the early steps of root hair formation revealed by the cellulose synthase mutant of "</p><p>http://www.biomedcentral.com/1471-2229/8/57</p><p>BMC Plant Biology 2008;8():57-57.</p><p>Published online 16 May 2008</p><p>PMCID:PMC2396171.</p><p></p

Оценка и пути повышения конкурентоспособности промышленного предприятия (на примере ОАО «8 Марта»)

The coordination of cell polarity within the plane of the tissue layer (planar polarity) is crucial for the development of diverse multicellular organisms. Small Rac/Rho-family GTPases and the actin cytoskeleton contribute to planar polarity formation at sites of polarity establishment in animals and plants. Yet, upstream pathways coordinating planar polarity differ strikingly between kingdoms. In the root of Arabidopsis thaliana, a concentration gradient of the phytohormone auxin coordinates polar recruitment of Rho-of-plant (ROP) to sites of polar epidermal hair initiation. However, little is known about cytoskeletal components and interactions that contribute to this planar polarity or about their relation to the patterning machinery. Here, we show that ACTIN7 (ACT7) represents a main actin isoform required for planar polarity of root hair positioning, interacting with the negative modulator ACTIN-INTERACTING PROTEIN1-2 (AIP1-2). ACT7, AIP1-2 and their genetic interaction are required for coordinated planar polarity of ROP downstream of ethylene signalling. Strikingly, AIP1-2 displays hair cell file-enriched expression, restricted by WEREWOLF (WER)-dependent patterning and modified by ethylene and auxin action. Hence, our findings reveal AIP1-2, expressed under control of the WER-dependent patterning machinery and the ethylene signalling pathway, as a modulator of actin-mediated planar polarity