scholarly journals Use of Green Fluorescent Protein Color Variants Expressed on Stable Broad-Host-Range Vectors to Visualize Rhizobia Interacting with Plants

2000 ◽  
Vol 13 (11) ◽  
pp. 1163-1169 ◽  
Author(s):  
Nico Stuurman ◽  
Cristina Pacios Bras ◽  
Helmi R. M. Schlaman ◽  
André H. M. Wijfjes ◽  
Guido Bloemberg ◽  
...  
Keyword(s):  
Green Fluorescent Protein ◽  
Host Range ◽  
Laser Scanning ◽  
Fluorescent Protein ◽  
Yellow Fluorescent Protein ◽  
Confocal Laser ◽  
Broad Host Range ◽  
Enhanced Yellow Fluorescent Protein ◽  
Green Fluorescent ◽  
Color Variants

We developed two sets of broad-host-range vectors that drive expression of the green fluorescent protein (GFP) or color variants thereof (henceforth collectively called autofluorescent proteins [AFPs]) from the lac promoter. These two sets are based on different replicons that are maintained in a stable fashion in Escherichia coli and rhizobia. Using specific filter sets or a dedicated confocal laser scanning microscope setup in which emitted light is split into its color components through a prism, we were able to unambiguously identify bacteria expressing enhanced cyan fluorescent protein (ECFP) or enhanced yellow fluorescent protein (EYFP) in mixtures of the two. Clearly, these vectors will be valuable tools for competition, cohabitation, and rescue studies and will also allow the visualization of interactions between genetically marked bacteria in vivo. Here, we used these vectors to visualize the interaction between rhizobia and plants. Specifically, we found that progeny from different rhizobia can be found in the same nodule or even in the same infection thread. We also visualized movements of bacteroids within plant nodule cells.

scholarly journals Simultaneous Visualization of the Yellow and Green Forms of the Green Fluorescent Protein in Living Cells

1998 ◽  
Vol 46 (9) ◽  
pp. 1073-1076 ◽  
Author(s):  
Chris T. Baumann ◽  
Carol S. Lim ◽  
Gordon L. Hager
Keyword(s):  
Green Fluorescent Protein ◽  
Laser Scanning ◽  
Fluorescent Protein ◽  
Yellow Fluorescent Protein ◽  
Simultaneous Detection ◽  
Argon Laser ◽  
Living Cells ◽  
Left Shoulder ◽  
Enhanced Yellow Fluorescent Protein ◽  
Green Fluorescent

In this study we sought to develop a method for the co-localization of proteins in living cells utilizing the enhanced green fluorescent protein (EGFP) and a redshifted EGFP variant, EYFP (enhanced yellow fluorescent protein). EYFP was expressed as an unsubstituted molecule while EGFP was fused to NF1 (EGFP-NF1), a transcription factor found exclusively in the nucleus. The Leica TCS SP laser scanning confocal microscope was used. This microscope allows the user to monitor the emitted light at defined wavelengths owing to the presence of a monochrometer in the emission light path. pEGFP-NF1 and pEYFP were co-expressed in the same cell and excited with the 476–nm and 488–nm argon laser lines. To separate the EYFP and EGFP fluorescence, EGFP-NF1 emission was recorded between 496 and 505 nm. These wavelengths are on the left shoulder of the EGFP emission peak and exclude most of the EYFP fluorescence. The EYFP emission was followed between 670 and 754 nm, utilizing the tail of EYFP emission that extends well beyond that for EGFP. Under these conditions we obtained excellent discrimination between EYFP fluorescence and EGFP-NF1 emission. These observations demonstrate that EYFP- and EGFP-substituted chimeras can be used for simultaneous detection in living cells.

Postharvest Handling Conditions Affect Internalization of Salmonella in Baby Spinach during Washing

2013 ◽  
Vol 76 (7) ◽  
pp. 1145-1151 ◽  
Author(s):  
VICENTE M. GÓMEZ-LÓPEZ ◽  
ALICIA MARÍN ◽  
ANA ALLENDE ◽  
LARRY R. BEUCHAT ◽  
MARÍA I. GIL
Keyword(s):  
Green Fluorescent Protein ◽  
Laser Scanning ◽  
Fluorescent Protein ◽  
Negative Temperature ◽  
Laser Scanning Microscopy ◽  
Confocal Laser ◽  
Temperature Differential ◽  
Postharvest Handling ◽  
Green Fluorescent ◽  
Spinach Leaves

Internalization of foodborne pathogens in fruits and vegetables is an increasing safety concern. The aim of this research was to assess the potential for internalization of an enteric pathogen (Salmonella enterica serotype Typhimurium) in a leafy vegetable (baby spinach) during washing as influenced by three postharvest handling conditions: (i) illumination, (ii) negative temperature differential, and (iii) relative humidity (RH). To compare these potential postharvest handling conditions, leaves were exposed to different levels of illumination (0, 1,000, and 2,000 lx), temperature differential (5, 11, 14, 20, and 26uC), and RH (99, 85, and 74%) for a short time before or during washing. Washing of baby spinach was carried out in water containing green fluorescent protein–tagged Salmonella Typhimurium (6.5 log CFU/ml) at 5uC for 2 min, followed by surface disinfection with chlorine (10,000 μg/ml) for 1 min, two rinses in water for 10 s, and spin drying for 15 s. Internalization was assessed by enumerating the pathogen on Salmonella-Shigella agar and by confocal laser scanning microscopy. Illumination of spinach leaves before and during washing and a negative temperature differential during washing did not significantly (P > 0.05) increase the number of internalized bacteria. However, exposure of leaves to low-RH conditions before washing, which reduced the tissue water content, decreased internalization of Salmonella compared with internalization in baby spinach exposed to high RH (P ≤ 0.05). Green fluorescent protein–tagged Salmonella Typhimurium was visualized by confocal laser scanning microscopy at a depth of up to 30 μm beneath the surface of spinach leaves after exposure to a high inoculum level (8 log CFU/ml) for an extended time (2 h). Results show that internalization of Salmonella into baby spinach leaves can occur but can be minimized under specific postharvest handling conditions such as low RH.

Migration of Salmonella Enteritidis Phage Type 30 through Almond Hulls and Shells

2008 ◽  
Vol 71 (2) ◽  
pp. 397-401 ◽  
Author(s):  
MICHELLE D. DANYLUK ◽  
MARIA T. BRANDL ◽  
LINDA J. HARRIS
Keyword(s):  
Green Fluorescent Protein ◽  
Laser Scanning ◽  
Salmonella Enteritidis ◽  
Fluorescent Protein ◽  
Phage Type ◽  
Laser Scanning Microscopy ◽  
Confocal Laser ◽  
Aqueous Environment ◽  
Serovar Typhimurium ◽  
Green Fluorescent

The ability of Salmonella to migrate from an external aqueous environment through the almond hull and shell, and to colonize the kernel, was evaluated in two ways. First, the outer surface of shell halves from five varieties of almonds that differed in shell hardness were placed in contact with a suspension of Salmonella enterica serovar Enteritidis phage type 30 for 24hat24°C. Salmonella Enteritidis was isolated from the inside of these almond shells in 46 and 100% of the samples, by direct swabbing of the inner surface of the shell and by enrichment from the swab, respectively. These findings suggested that hardness of the shell is not a significant factor in the migration of the pathogen through that tissue. In addition, both motile and nonmotile strains of S. enterica serovar Typhimurium migrated through the almond shells to the same extent under the conditions of this assay, indicating that bacterial migration through the wet shell may be a passive process. Second, whole almonds (intact hull, shell, and kernel) were soaked for 24 to 72 h at 24°C in a suspension of Salmonella Enteritidis phage type 30 labeled with the green fluorescent protein. Green fluorescent protein–labeled Salmonella cells were observed on the outer and inner surfaces of both the almond hull and shell, and on the kernel, by confocal laser scanning microscopy. Our data provide direct evidence that wet conditions allow for Salmonella migration through the hull and shell and onto the almond kernel, thus providing a means by which almond kernels may become contaminated in the field.

scholarly journals Systemic Colonization of Potato Plants by a Soilborne, Green Fluorescent Protein-Tagged Strain of Dickeya sp. Biovar 3

2010 ◽  
Vol 100 (2) ◽  
pp. 134-142 ◽  
Author(s):  
Robert Czajkowski ◽  
Waldo J. de Boer ◽  
Henk Velvis ◽  
Jan M. van der Wolf
Keyword(s):  
Green Fluorescent Protein ◽  
Laser Scanning ◽  
Fluorescent Protein ◽  
Agar Medium ◽  
Lateral Roots ◽  
Laser Scanning Microscopy ◽  
Confocal Laser ◽  
Potato Plants ◽  
Soil Inoculation ◽  
Green Fluorescent

Colonization of potato plants by soilborne, green fluorescent protein (GFP)-tagged Dickeya sp. IPO2254 was investigated by selective plating, epifluorescence stereo microscopy (ESM), and confocal laser scanning microscopy (CLSM). Replicated experiments were carried out in a greenhouse using plants with an intact root system and plants from which ca. 30% of the lateral roots was removed. One day after soil inoculation, adherence of the pathogen on the roots and the internal colonization of the plants were detected using ESM and CLSM of plant parts embedded in an agar medium. Fifteen days post-soil inoculation, Dickeya sp. was found on average inside 42% of the roots, 13% of the stems, and 13% of the stolons in plants with undamaged roots. At the same time-point, in plants with damaged roots, Dickeya sp. was found inside 50% of the roots, 25% of the stems, and 25% of the stolons. Thirty days postinoculation, some plants showed true blackleg symptoms. In roots, Dickeya sp. was detected in parenchyma cells of the cortex, both inter- and intracellularly. In stems, bacteria were found in xylem vessels and in protoxylem cells. Microscopical observations were confirmed by dilution spread-plating the plant extracts onto agar medium directly after harvest. The implications of infection from soilborne inoculum are discussed.

scholarly journals Green Fluorescent Protein-Marked Pseudomonas fluorescens: Localization, Viability, and Activity in the Natural Barley Rhizosphere

1999 ◽  
Vol 65 (10) ◽  
pp. 4646-4651 ◽  
Author(s):  
Bo Normander ◽  
Niels B. Hendriksen ◽  
Ole Nybroe
Keyword(s):  
Green Fluorescent Protein ◽  
Pseudomonas Fluorescens ◽  
Laser Scanning ◽  
Fluorescent Protein ◽  
Green Fluorescent Protein Fluorescence ◽  
Laser Scanning Microscopy ◽  
Confocal Laser ◽  
Protein Fluorescence ◽  
Dividing Cells ◽  
Green Fluorescent

ABSTRACT The gfp-tagged Pseudomonas fluorescensbiocontrol strain DR54-BN14 was introduced into the barley rhizosphere. Confocal laser scanning microscopy revealed that the rhizoplane populations of DR54-BN14 on 3- to 14-day-old roots were able to form microcolonies closely associated with the indigenous bacteria and that a majority of DR54-BN14 cells appeared small and almost coccoid. Information on the viability of the inoculant was provided by a microcolony assay, while measurements of cell volume, the intensity of green fluorescent protein fluorescence, and the ratio of dividing cells to total cells were used as indicators of cellular activity. At a soil moisture close to the water-holding capacity of the soil, the activity parameters suggested that the majority of DR54-BN14 cells were starving in the rhizosphere. Nevertheless, approximately 80% of the population was either culturable or viable but nonculturable during the 3-week incubation period. No impact of root decay on viability was observed, and differences in viability or activity among DR54-BN14 cells located in different regions of the root were not apparent. In dry soil, however, the nonviable state of DR54-BN14 was predominant, suggesting that desiccation is an important abiotic regulator of cell viability.

scholarly journals Spitzenkörper Localization and Intracellular Traffic of Green Fluorescent Protein-Labeled CHS-3 and CHS-6 Chitin Synthases in Living Hyphae of Neurospora crassa

2007 ◽  
Vol 6 (10) ◽  
pp. 1853-1864 ◽  
Author(s):  
Meritxell Riquelme ◽  
Salomon Bartnicki-García ◽  
Juan Manuel González-Prieto ◽  
Eddy Sánchez-León ◽  
Jorge A. Verdín-Ramos ◽  
...  
Keyword(s):  
Green Fluorescent Protein ◽  
Neurospora Crassa ◽  
Laser Scanning ◽  
Fluorescent Dyes ◽  
Fluorescent Protein ◽  
Golgi Body ◽  
Laser Scanning Microscopy ◽  
Confocal Laser ◽  
Chitin Synthases ◽  
Green Fluorescent

ABSTRACT The subcellular location and traffic of two selected chitin synthases (CHS) from Neurospora crassa, CHS-3 and CHS-6, labeled with green fluorescent protein (GFP), were studied by high-resolution confocal laser scanning microscopy. While we found some differences in the overall distribution patterns and appearances of CHS-3-GFP and CHS-6-GFP, most features were similar and were observed consistently. At the hyphal apex, fluorescence congregated into a conspicuous single body corresponding to the location of the Spitzenkörper (Spk). In distal regions (beyond 40 μm from the apex), CHS-GFP revealed a network of large endomembranous compartments that was predominantly comprised of irregular tubular shapes, while some compartments were distinctly spherical. In the distal subapex (20 to 40 μm from the apex), fluorescence was observed in globular bodies that appeared to disintegrate into vesicles as they advanced forward until reaching the proximal subapex (5 to 20 μm from the apex). CHS-GFP was also conspicuously found delineating developing septa. Analysis of fluorescence recovery after photobleaching suggested that the fluorescence of the Spk originated from the advancing population of microvesicles (chitosomes) in the subapex. The inability of brefeldin A to interfere with the traffic of CHS-containing microvesicles and the lack of colocalization of CHS-GFP with the endoplasmic reticulum (ER)-Golgi body fluorescent dyes lend support to the idea that CHS proteins are delivered to the cell surface via an alternative route distinct from the classical ER-Golgi body secretory pathway.

Use of Green Fluorescent Protein To Tag and Investigate Gene Expression in Marine Bacteria

1998 ◽  
Vol 64 (7) ◽  
pp. 2554-2559 ◽  
Author(s):  
Serina Stretton ◽  
Somkiet Techkarnjanaruk ◽  
Alan M. McLennan ◽  
Amanda E. Goodman
Keyword(s):  
Gene Expression ◽  
Green Fluorescent Protein ◽  
Marine Bacteria ◽  
Laser Scanning ◽  
Fluorescent Protein ◽  
Single Cells ◽  
Bacterial Species ◽  
Epifluorescence Microscopy ◽  
Broad Host Range ◽  
Green Fluorescent

ABSTRACT Two broad-host-range vectors previously constructed for use in soil bacteria (A. G. Matthysse, S. Stretton, C. Dandie, N. C. McClure, and A. E. Goodman, FEMS Microbiol. Lett. 145:87–94, 1996) were assessed by epifluorescence microscopy for use in tagging three marine bacterial species. Expression of gfp could be visualized in Vibrio sp. strain S141 cells at uniform levels of intensity from either the lac or thenpt-2 promoter, whereas expression of gfp could be visualized in Psychrobacter sp. strain SW5H cells at various levels of intensity only from the npt-2 promoter. Green fluorescent protein (GFP) fluorescence was not detected in the third species, Pseudoalteromonas sp. strain S91, when thegfp gene was expressed from either promoter. A new mini-Tn10-kan-gfp transposon was constructed to investigate further the possibilities of fluorescence tagging of marine bacteria. Insertion of mini-Tn10-kan-gfp generated random stable mutants at high frequencies with all three marine species. With this transposon, strongly and weakly expressed S91 promoters were isolated. Visualization of GFP by epifluorescence microscopy was markedly reduced when S91 (mini-Tn10-kan-gfp) cells were grown in rich medium compared to that when cells were grown in minimal medium. Mini-Tn10-kan-gfp was used to create an S91 chitinase-negative, GFP-positive mutant. Expression of the chi-gfp fusion was induced in cells exposed toN′-acetylglucosamine or attached to chitin particles. By laser scanning confocal microscopy, biofilms consisting of microcolonies of chi-negative, GFP+ S91 cells were found to be localized several microns from a natural chitin substratum. Tagging bacterial strains with GFP enables visualization of, as well as monitoring of gene expression in, living single cells in situ and in real time.

Green fluorescent protein: Use of GFP-chimeras in the analysis of microtubule-associated protein 4 domains and microtubule dynamics

1996 ◽  
Vol 54 ◽  
pp. 888-889
Author(s):  
J.B. Olmsted ◽  
K.R. Olson ◽  
M.L. Gonzalez-Garay ◽  
F. Cabral
Keyword(s):  
Green Fluorescent Protein ◽  
Laser Scanning ◽  
Fluorescent Protein ◽  
Laser Scanning Microscopy ◽  
Confocal Laser ◽  
Gfp Reporter ◽  
Associated Proteins ◽  
Potential Applications ◽  
Exogenous Expression ◽  
Green Fluorescent

Green Fluorescent Protein (GFP) is an endogenous 27 kDa fluorophore of the jellyfish, Aequorea victoria. Chalfie et al., first described the exogenous expression of this molecule in bacteria, and its utility as a reporter in higher eukaryotes. Potential applications of GFP have been expanded through the construction of variants with enhanced brightness and/or different spectral properties.We have explored using GFP for the analysis of the real-time behaviors of microtubules and their associated proteins. Constructs of microtubule-associated protein 4 (MAP 4) or β-tubulin were generated in pRC/CMV vectors and used in either transient or stable transfection assays in a variety of cultured cell lines (3T3, PtKl, BHK, CHO, Cos). The GFP-chimeras were visualized using conventional fluorescence microscopy and confocal laser scanning microscopy. Unusual features of the GFP reporter are that fluorescence intensity increased 2-10 fold upon illumination, and that phototoxicity was low.

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