scholarly journals Phytohormone Priming of Tomato Plants Evoke Differential Behavior in Rhizoctonia solani During Infection, With Salicylate Priming Imparting Greater Tolerance Than Jasmonate

2022 ◽  
Vol 12 ◽  
Author(s):  
Paulami Koley ◽  
Subhadip Brahmachari ◽  
Amitava Saha ◽  
Camelia Deb ◽  
Monimala Mondal ◽  
...  
Keyword(s):  
Rhizoctonia Solani ◽  
Laser Scanning ◽  
Time Course ◽  
Green Fluorescence Protein ◽  
Laser Scanning Microscopy ◽  
Early Infection ◽  
Confocal Laser ◽  
Marker Genes ◽  
Necrotrophic Pathogen ◽  
Tomato Plants

In the field of phytohormone defense, the general perception is that salicylate (SA)-mediated defense is induced against biotrophic pathogens while jasmonate (JA)-mediated defense functions against necrotrophic pathogens. Our goals were to observe the behavior of the necrotrophic pathogen Rhizoctonia solani in the vicinity, on the surface, and within the host tissue after priming the host with SA or JA, and to see if priming with these phytohormones would affect the host defense differently upon infection. It was observed for the first time, that R. solani could not only distinguish between JA versus SA-primed tomato plants from a distance, but surprisingly avoided SA-primed plants more than JA-primed plants. To corroborate these findings, early infection events were monitored and compared through microscopy, Scanning Electron Microscopy, and Confocal Laser Scanning Microscopy using transformed R. solani expressing green fluorescence protein gene (gfp). Different histochemical and physiological parameters were compared between the unprimed control, JA-primed, and SA-primed plants after infection. The expression of a total of fifteen genes, including the appressoria-related gene of the pathogen and twelve marker genes functioning in the SA and JA signaling pathways, were monitored over a time course during early infection stages. R. solani being traditionally designated as a necrotroph, the major unexpected observations were that Salicylate priming offered better tolerance than Jasmonate priming and that it was mediated through the activation of SA-mediated defense during the initial phase of infection, followed by JA-mediated defense in the later phase. Hence, the present scenario of biphasic SA-JA defense cascades during R. solani infection, with SA priming imparting maximum tolerance, indicate a possible hemibiotrophic pathosystem that needs to be investigated further.

The fate of medial edge epithelial cells during palatal fusion in vitro: an analysis by DiI labelling and confocal microscopy

Development ◽  
1992 ◽  
Vol 114 (2) ◽  
pp. 379-388 ◽  
Author(s):  
M.J. Carette ◽  
M.W. Ferguson
Keyword(s):  
Laser Scanning ◽  
Time Course ◽  
Laser Scanning Microscopy ◽  
Confocal Laser ◽  
Palatal Fusion ◽  
Morphological Criteria ◽  
Medial Edge ◽  
Mesenchymal Transformation

Fusion of bilateral shelves, to form the definitive mammalian secondary palate, is critically dependent on removal of the medial edge cells that constitute the midline epithelial seam. Conflicting views suggest that programmed apoptotic death or epithelial-mesenchymal transformation of these cells is predominantly involved. Due in part to the potentially ambiguous interpretation of static images and the notable absence of fate mapping studies, the process by which this is achieved has, however, remained mechanistically equivocal. Using an in vitro mouse model, we have selectively labelled palatal epithelia with DiI and examined the fate of medial edge epithelial (MEE) cells during palatal fusion by localisation using a combination of conventional histology and confocal laser scanning microscopy (CLSM). In dynamic studies using CLSM, we have made repetitive observations of the same palatal cultures in time-course investigations. Our results concurred with the established morphological criteria of seam degeneration; however, they provided no evidence of MEE cell death or transformation. Instead we report that MEE cells migrate nasally and orally out of the seam and are recruited into, and constitute, epithelial triangles on both the oral and nasal aspects of the palate. Subsequently these cells become incorporated into the oral and nasal epithelia on the surface of the palate. We hypothesize an alternative method of seam degeneration in vivo which largely conserves the MEE population by recruiting it into the nasal and oral epithelia.

Tyrosine phosphorylation following alterations in arteriolar intraluminal pressure and wall tension

2001 ◽  
Vol 281 (3) ◽  
pp. H1047-H1056 ◽  
Author(s):  
Timothy V. Murphy ◽  
Brian E. Spurrell ◽  
Michael A. Hill
Keyword(s):  
Tyrosine Phosphorylation ◽  
Fluorescence Intensity ◽  
Laser Scanning ◽  
Time Course ◽  
Transmural Pressure ◽  
Laser Scanning Microscopy ◽  
Intraluminal Pressure ◽  
Confocal Laser ◽  
Wall Tension ◽  
Myogenic Activity

Arterioles respond to increased transmural pressure with myogenic constriction. The present study investigated the role of tyrosine phosphorylation in myogenic activity. Cannulated segments of a rat cremaster arteriole were fixed under pressure, followed by incubation with fluorescein isothiocyanate (FITC)-conjugated anti-phosphotyrosine. Smooth muscle cell fluorescence intensity was measured with the use of confocal laser-scanning microscopy. Anti-phosphotyrosine fluorescence intensity in muscle cells of arterioles maintained at 100 mmHg was reduced by the tyrosine kinase inhibitor tyrphostin A47 (30 μM) and increased by the tyrosine phosphatase inhibitor pervanadate (100 μM). In time-course experiments, anti-phosphotyrosine fluorescence increased slowly (over 5 min) after an acute increase in intraluminal pressure, and was dissociated from myogenic contraction (within 1 min). In contrast, angiotensin II (0.1 μM) caused rapid constriction and increased tyrosine phosphorylation. Anti-phosphotyrosine fluorescence was also pressure dependent (10–100 mmHg). Abolition of myogenic activity, either through removal of extracellular Ca2+, or exposure to verapamil (5 μM) or forskolin (0.1 μM) caused a further increase in anti-phosphotyrosine fluorescence. We conclude that transmural pressure and/or wall tension in arterioles causes increased tyrosine phosphorylation; however, this is not involved in the acute phase of myogenic constriction but may be involved in later responses, such as sustained myogenic tone or mechanisms possibly related to growth.

scholarly journals Effect of arsenite on swimming motility delays surface colonization in Herminiimonas arsenicoxydans

Microbiology ◽  
2010 ◽  
Vol 156 (8) ◽  
pp. 2336-2342 ◽  
Author(s):  
M. Marchal ◽  
R. Briandet ◽  
S. Koechler ◽  
B. Kammerer ◽  
P. N. Bertin
Keyword(s):  
Laser Scanning ◽  
Time Course ◽  
Wild Type Strain ◽  
Laser Scanning Microscopy ◽  
Confocal Laser ◽  
Wild Type ◽  
Arsenite Oxidase ◽  
Swimming Motility ◽  
In The Wild ◽  
Biofilm Development

Herminiimonas arsenicoxydans is a Gram-negative bacterium able to detoxify arsenic-contaminated environments by oxidizing arsenite [As(III)] to arsenate [As(V)] and by scavenging arsenic ions in an extracellular matrix. Its motility and colonization behaviour have been previously suggested to be influenced by arsenite. Using time-course confocal laser scanning microscopy, we investigated its biofilm development in the absence and presence of arsenite. Arsenite was shown to delay biofilm initiation in the wild-type strain; this was partly explained by its toxicity, which caused an increased growth lag time. However, this delayed adhesion step in the presence of arsenite was not observed in either a swimming motility defective fliL mutant or an arsenite oxidase defective aoxB mutant; both strains displayed the wild-type surface properties and growth capacities. We propose that during the biofilm formation process arsenite acts on swimming motility as a result of the arsenite oxidase activity, preventing the switch between planktonic and sessile lifestyles. Our study therefore highlights the existence, under arsenite exposure, of a competition between swimming motility, resulting from arsenite oxidation, and biofilm initiation.

scholarly journals A Protein Kinase A-Dependent Mechanism by Which Rotavirus Affects the Distribution and mRNA Level of the Functional Tight Junction-Associated Protein, Occludin, in Human Differentiated Intestinal Caco-2 Cells

2007 ◽  
Vol 81 (16) ◽  
pp. 8579-8586 ◽  
Author(s):  
Isabelle Beau ◽  
Jacqueline Cotte-Laffitte ◽  
Raymonde Amsellem ◽  
Alain L. Servin
Keyword(s):  
Protein Kinase ◽  
Protein Kinase A ◽  
Laser Scanning ◽  
Time Course ◽  
Mrna Level ◽  
Laser Scanning Microscopy ◽  
Confocal Laser ◽  
Infected Cells ◽  
Triton X ◽  
Kinase A

ABSTRACT We found that at the tight junctions (TJs) of Caco-2 cell monolayers, rhesus monkey rotavirus (RRV) infection induced the disappearance of occludin. Confocal laser scanning microscopy showed the disappearance of occludin from the cell-cell boundaries without modifying the expression of the other TJ-associated proteins, ZO-1 and ZO-3. Western immunoblot analysis of RRV-infected cells showed a significant fall in the levels of the nonphosphorylated form of occludin in both Triton X-100-insoluble and Triton X-100-soluble fractions, without any change in the levels of the phosphorylated form of occludin. Quantitative reverse transcription-PCRs revealed that the level of transcription of the gene that encodes occludin was significantly reduced in RRV-infected cells. Treatment of RRV-infected cells with Rp-cyclic AMP and protein kinase A inhibitors H89 and KT5720 during the time course of the infection restored the distribution of occludin and a normal level of transcription of the gene that encodes occludin.

scholarly journals Xylella fastidiosa subsp. pauca and fastidiosa Colonize Arabidopsis Systemically and Induce Anthocyanin Accumulation in Infected Leaves

2019 ◽  
Vol 109 (2) ◽  
pp. 225-232 ◽  
Author(s):  
W. E. L. Pereira ◽  
C. B. Ferreira ◽  
R. Caserta ◽  
M. Melotto ◽  
A. A. de Souza
Keyword(s):  
Laser Scanning ◽  
Time Course ◽  
Xylella Fastidiosa ◽  
Olive Tree ◽  
Laser Scanning Microscopy ◽  
Confocal Laser ◽  
Anthocyanin Accumulation ◽  
Bacterial Populations ◽  
Host Interaction ◽  
Genetic Components

The bacterium Xylella fastidiosa is a multihost pathogen that affects perennial crops such as grapevine, sweet orange, and olive tree worldwide. It is inherently difficult to study these pathosystems owing to the long-term growth habit of the host plant. Thus, the availability of model plants becomes essential to accelerate discoveries with economic impact. In this study, we uncovered evidence that the model plant Arabidopsis thaliana can be colonized by two different X. fastidiosa subspecies, pauca and fastidiosa. We observed that these bacteria are able to move away from the inoculation point as high bacterial populations were found in distant tissues. In addition, confocal laser scanning microscopy analysis of bacterial movement inside the petiole revealed the ability of the bacterium to move against the net xylem flow during the time course of colonization forming biofilm. These findings provide evidence for the capacity of X. fastidiosa to colonize Arabidopsis. Furthermore, leaves inoculated with X. fastidiosa showed a significant accumulation of anthocyanin. We propose that the X. fastidiosa subsp. pauca or fastidiosa colonization pattern and anthocyanin accumulation in the Arabidopsis ecotype Col-0 can be used as marker phenotypes to facilitate further studies aimed at improving genetic components involved in X. fastidiosa−host interaction.

scholarly journals Genetic Features of Resident Biofilms Determine Attachment of Listeria monocytogenes

2009 ◽  
Vol 75 (24) ◽  
pp. 7814-7821 ◽  
Author(s):  
Olivier Habimana ◽  
Mickael Meyrand ◽  
Thierry Meylheuc ◽  
Saulius Kulakauskas ◽  
Romain Briandet
Keyword(s):  
Listeria Monocytogenes ◽  
Laser Scanning ◽  
Time Course ◽  
Surface Hydrophobicity ◽  
Flow Cell ◽  
Laser Scanning Microscopy ◽  
Confocal Laser ◽  
Microscopy Imaging ◽  
Initial Fixation ◽  
Genetic Features

ABSTRACT Planktonic Listeria monocytogenes cells in food-processing environments tend most frequently to adhere to solid surfaces. Under these conditions, they are likely to encounter resident biofilms rather than a raw solid surface. Although metabolic interactions between L. monocytogenes and resident microflora have been widely studied, little is known about the biofilm properties that influence the initial fixation of L. monocytogenes to the biofilm interface. To study these properties, we created a set of model resident Lactococcus lactis biofilms with various architectures, types of matrices, and individual cell surface properties. This was achieved using cell wall mutants that affect bacterial chain formation, exopolysaccharide (EPS) synthesis and surface hydrophobicity. The dynamics of the formation of these biofilm structures were analyzed in flow cell chambers using in situ time course confocal laser scanning microscopy imaging. All the L. lactis biofilms tested reduced the initial immobilization of L. monocytogenes compared to the glass substratum of the flow cell. Significant differences were seen in L. monocytogenes settlement as a function of the genetic background of resident lactococcal biofilm cells. In particular, biofilms of the L. lactis chain-forming mutant resulted in a marked increase in L. monocytogenes settlement, while biofilms of the EPS-secreting mutant efficiently prevented pathogen fixation. These results offer new insights into the role of resident biofilms in governing the settlement of pathogens on food chain surfaces and could be of relevance in the field of food safety controls.

scholarly journals News Insights into the Host-Parasite Interactions of Amyloodiniosis in European Sea Bass: A Multi-Modal Approach

Pathogens ◽  
2022 ◽  
Vol 11 (1) ◽  
pp. 62
Author(s):  
Michela Massimo ◽  
Donatella Volpatti ◽  
Marco Galeotti ◽  
James E. Bron ◽  
Paola Beraldo
Keyword(s):  
Laser Scanning ◽  
Time Course ◽  
Parasite Burden ◽  
Sea Bass ◽  
Laser Scanning Microscopy ◽  
Confocal Laser ◽  
Cell Degeneration ◽  
European Sea Bass ◽  
Starting Point ◽  
Host Parasite

Amyloodiniosis is a disease resulting from infestation by the ectoparasitic dinoflagellate Amyloodinium ocellatum (AO) and is a threat for fish species such as European sea bass (ESB, Dicentrarchus labrax), which are farmed in lagoon and land-based rearing sites. During the summer, when temperatures are highest, mortality rates can reach 100%, with serious impacts for the aquaculture industry. As no effective licensed therapies currently exist, this study was undertaken to improve knowledge of the biology of AO and of the host-parasite relationship between the protozoan and ESB, in order to formulate better prophylactic/therapeutic treatments targeting AO. To achieve this, a multi-modal study was performed involving a broad range of analytical modalities, including conventional histology (HIS), immunohistochemistry (IHC) and confocal laser scanning microscopy (CLSM). Gills and the oro-pharyngeal cavity were the primary sites of amyloodiniosis, with hyperplasia and cell degeneration more evident in severe infestations (HIS). Plasmacells and macrophages were localised by IHC and correlated with the parasite burden in a time-course experimental challenge. CLSM allowed reconstruction of the 3D morphology of infecting trophonts and suggested a protein composition for its anchoring and feeding structures. These findings provide a potential starting point for the development of new prophylactic/therapeutic controls.

scholarly journals Biofilm Formation by the Fish Pathogen Flavobacterium columnare: Development and Parameters Affecting Surface Attachment

2013 ◽  
Vol 79 (18) ◽  
pp. 5633-5642 ◽  
Author(s):  
Wenlong Cai ◽  
Leonardo De La Fuente ◽  
Covadonga R. Arias
Keyword(s):  
Biofilm Formation ◽  
Laser Scanning ◽  
Time Course ◽  
Laser Scanning Microscopy ◽  
Confocal Laser ◽  
Freshwater Species ◽  
Flavobacterium Columnare ◽  
Fish Pathogen ◽  
Flow Conditions ◽  
Content Type

ABSTRACTFlavobacterium columnareis a bacterial fish pathogen that affects many freshwater species worldwide. The natural reservoir of this pathogen is unknown, but its resilience in closed aquaculture systems posits biofilm as the source of contagion for farmed fish. The objectives of this study were (i) to characterize the dynamics of biofilm formation and morphology under static and flow conditions and (ii) to evaluate the effects of temperature, pH, salinity, hardness, and carbohydrates on biofilm formation. NineteenF. columnarestrains, including representatives of all of the defined genetic groups (genomovars), were compared in this study. The structure of biofilm was characterized by light microscopy, confocal laser scanning microscopy, and scanning electron microscopy.F. columnarewas able to attach to and colonize inert surfaces by producing biofilm. Surface colonization started within 6 h postinoculation, and microcolonies were observed within 24 h. Extracellular polysaccharide substances and water channels were observed in mature biofilms (24 to 48 h). A similar time course was observed whenF. columnareformed biofilm in microfluidic chambers under flow conditions. The virulence potential of biofilm was confirmed by cutaneous inoculation of channel catfish fingerlings with mature biofilm. Several physicochemical parameters modulate attachment to surfaces, with the largest influence being exerted by hardness, salinity, and the presence of mannose. Maintenance of hardness and salinity values within certain ranges could prevent biofilm formation byF. columnarein aquaculture systems.

Recognition of a pathogen and a nonpathogen by barley coleoptile cells. III. Responses of microtubules and actin filaments in barley coleoptile cells to penetration attempts

1992 ◽  
Vol 70 (9) ◽  
pp. 1815-1823 ◽  
Author(s):  
Issei Kobayashi ◽  
Yuhko Kobayashi ◽  
Naoto Yamaoka ◽  
Hitoshi Kunoh
Keyword(s):  
Confocal Laser Scanning Microscopy ◽  
Actin Filaments ◽  
Laser Scanning ◽  
Time Course ◽  
Laser Scanning Microscopy ◽  
Confocal Laser Scanning ◽  
Scanning Microscopy ◽  
Confocal Laser ◽  
Cortical Region ◽  
Erysiphe Pisi

New arrangements of microtubules and actin filaments in coleoptile cells of barley that had been inoculated with either a nonpathogen, Erysiphe pisi, or a pathogen, E. graminis, were observed by cytochemistry and confocal laser scanning microscopy. In uninoculated coleoptile cells, microtubules were oriented almost obliquely or transversely to the long axis of the cells and actin filaments almost obliquely or longitudinally. A thick actin bundle was located beneath approximately 70% of appressoria of E. pisi when the appressoria matured 3–4 h before they attempted penetration. This phenomenon occurred below approximately 30% of appressoria of E. graminis. Microtubules were gathered beneath the appressoria when and after the inoculated fungi induced cytoplasmic aggregation. This phenomenon also occurred more frequently below appressoria of E. pisi than those of E. graminis. Confocal laser scanning microscopy confirmed the localization of microtubules and actin filaments in a cortical region of the coleoptile cell beneath the appressorium. The time-course study revealed that the new arrangement of actin filaments was initiated 3–4 h prior to the fungal penetration attempt, whereas that of microtubules began at the time of initiation of cytoplasmic aggregation. The incidence of cells with newly arranged cytoskeletons was distinctly higher when E. pisi rather than E. graminis was used as inoculum. The possibilities that actin filaments might be involved in sensing the presence of the fungi and that both microtubules and actin filaments might be involved in localized resistance mechanisms are discussed. Key words: microtubule, F-actin, Erysiphe pisi, E. graminis, resistance mechanism.

scholarly journals Contribution of alginate and levan production to biofilm formation by Pseudomonas syringae

Microbiology ◽  
2006 ◽  
Vol 152 (10) ◽  
pp. 2909-2918 ◽  
Author(s):  
Heike Laue ◽  
Alexander Schenk ◽  
Hongqiao Li ◽  
Lotte Lambertsen ◽  
Thomas R. Neu ◽  
...  
Keyword(s):  
Spatial Distribution ◽  
Pseudomonas Syringae ◽  
Biofilm Formation ◽  
Laser Scanning ◽  
Time Course ◽  
Complex Structure ◽  
Laser Scanning Microscopy ◽  
Confocal Laser ◽  
Bacterial Cells ◽  
Biofilm Development

Exopolysaccharides (EPSs) play important roles in the attachment of bacterial cells to a surface and/or in building and maintaining the three-dimensional, complex structure of bacterial biofilms. To elucidate the spatial distribution and function of the EPSs levan and alginate during biofilm formation, biofilms of Pseudomonas syringae strains with different EPS patterns were compared. The mucoid strain PG4180.muc, which produces levan and alginate, and its levan- and/or alginate-deficient derivatives all formed biofilms in the wells of microtitre plates and in flow chambers. Confocal laser scanning microscopy with fluorescently labelled lectins was applied to investigate the spatial distribution of levan and an additional as yet unknown EPS in flow-chamber biofilms. Concanavalin A (ConA) bound specifically to levan and accumulated in cell-depleted voids in the centres of microcolonies and in blebs. No binding of ConA was observed in biofilms of the levan-deficient mutants or in wild-type biofilms grown in the absence of sucrose as confirmed by an enzyme-linked lectin-sorbent assay using peroxidase-linked ConA. Time-course studies revealed that expression of the levan-forming enzyme, levansucrase, occurred mainly during early exponential growth of both planktonic and sessile cells. Thus, accumulation of levan in biofilm voids hints to a function as a nutrient storage source for later stages of biofilm development. The presence of a third EPS besides levan and alginate was indicated by binding of the lectin from Naja mossambica to a fibrous structure in biofilms of all P. syringae derivatives. Production of the as yet uncharacterized additional EPS might be more important for biofilm formation than the syntheses of levan and alginate.

Sign in / Sign up

Export Citation Format

Share Document