Sensitive Bioassay for Detection of Biologically Active Ricin in Food

2012 ◽  
Vol 75 (5) ◽  
pp. 951-954 ◽  
Author(s):  
REUVEN RASOOLY ◽  
XIAOHUA HE
Keyword(s):  
Large Scale ◽  
Fluorescent Protein ◽  
Vero Cells ◽  
Biologically Active ◽  
Green Fluorescent Protein Gene ◽  
Mouse Bioassay ◽  
Human Embryonic Kidney Cells ◽  
Green Fluorescent ◽  
And Control

The potential use of ricin as an agent of biological warfare highlights the need to develop fast and effective methods to detect biologically active ricin. The current “gold standard” for ricin detection is an in vivo mouse bioassay; however, this method is not practical to test on a large number of samples and raises ethical concerns with regard to the use of experimental animals. In this work, we generated adenoviral vectors that express the green fluorescent protein gene and used the relative fluorescence units intensity inhibition by transduced cells for quantitative measurement of biologically active ricin. The detection limit of the assay was 200 pg/ml, which is over 500,000 times greater than the adult human lethal oral dose. The inhibition of fluorescence intensity between ricin treatment and control was higher in 72-h posttransduction Vero cells than 24-h human embryonic kidney cells. Therefore, to detect biologically active ricin in food matrices that might influence the assay, we used 72-h posttransduction Vero cells. This simple assay could be used for large-scale screening to detect biologically active ricin in food without added substrates or use of cell fixation methods.

Laser-induced gene expression in specific cells of transgenic zebrafish

Development ◽  
2000 ◽  
Vol 127 (9) ◽  
pp. 1953-1960 ◽  
Author(s):  
M.C. Halloran ◽  
M. Sato-Maeda ◽  
J.T. Warren ◽  
F. Su ◽  
Z. Lele ◽  
...  
Keyword(s):  
Green Fluorescent Protein ◽  
Fluorescent Protein ◽  
Green Fluorescent Protein Gene ◽  
Transgenic Zebrafish ◽  
Hsp70 Promoter ◽  
Expression Of Genes ◽  
Transgenic Lines ◽  
Transgenic Embryos ◽  
Green Fluorescent

Over the past few years, a number of studies have described the generation of transgenic lines of zebrafish in which expression of reporters was driven by a variety of promoters. These lines opened up the real possibility that transgenics could be used to complement the genetic analysis of zebrafish development. Transgenic lines in which the expression of genes can be regulated both in space and time would be especially useful. Therefore, we have cloned the zebrafish promoter for the inducible hsp70 gene and made stable transgenic lines of zebrafish that express the reporter green fluorescent protein gene under the control of a hsp70 promoter. At normal temperatures, green fluorescent protein is not detectable in transgenic embryos with the exception of the lens, but is robustly expressed throughout the embryo following an increase in ambient temperature. Furthermore, we have taken advantage of the accessibility and optical clarity of the embryos to express green fluorescent protein in individual cells by focussing a sublethal laser microbeam onto them. The targeted cells appear to develop normally: cells migrate normally, neurons project axons that follow normal pathways, and progenitor cells divide and give rise to normal progeny cells. By generating other transgenic lines in which the hsp70 promoter regulates genes of interest, it should be possible to examine the in vivo activity of the gene products by laser-inducing specific cells to express them in zebrafish embryos. As a first test, we laser-induced single muscle cells to make zebrafish Sema3A1, a semaphorin that is repulsive for specific growth cones, in a hsp70-sema3A1 transgenic line of zebrafish and found that extension by the motor axons was retarded by the induced muscle.

scholarly journals Retroviral-Mediated Transfer of the Green Fluorescent Protein Gene Into Murine Hematopoietic Cells Facilitates Scoring and Selection of Transduced Progenitors In Vitro and Identification of Genetically Modified Cells In Vivo

Blood ◽  
1997 ◽  
Vol 90 (5) ◽  
pp. 1777-1786 ◽  
Author(s):  
Derek A. Persons ◽  
James A. Allay ◽  
Esther R. Allay ◽  
Richard J. Smeyne ◽  
Richard A. Ashmun ◽  
...  
Keyword(s):  
Green Fluorescent Protein ◽  
Gene Transfer ◽  
Fluorescent Protein ◽  
High Titer ◽  
Hematopoietic Cells ◽  
Green Fluorescent Protein Gene ◽  
Retroviral Gene Transfer ◽  
Green Fluorescent ◽  
Marrow Cells

Abstract We have investigated the utility of the green fluorescent protein (GFP) to serve as a marker to assess retroviral gene transfer into hematopoietic cells and as a tool to identify and enrich for cells expressing high levels of the vector-encoded transcript. GFP, by virtue of a naturally occurring chromophore encoded in its primary sequence, displays autonomous fluorescence, thus eliminating the need for antibody or cytochemical staining to detect its expression. A bicistronic murine stem cell virus (MSCV)-based retroviral vector was constructed containing the GFP cDNA and a mutant, human dihydrofolate reductase gene. High-titer, ecotropic retroviral producer cells free of replication competent virus were generated and used to transduce murine bone marrow cells by cocultivation. Within 24 hours after completion of the transduction procedure, a high proportion (40% to 70%) of the marrow cells were intensely fluorescent compared to mock-transduced cells or cells transduced with a control retrovirus. Erythroid and myeloid hematopoietic colonies derived from GFP-transduced marrow were easily scored for retroviral gene transfer by direct in situ fluorescence microscopy. Clonogenic progenitors expressing increased levels of antifolate drug resistance could be enriched from the GFP-transduced marrow population by fluorescence activated cell sorting of cells expressing high levels of GFP. In vivo, splenic hematopoietic colonies and peripheral blood cells from animals transplanted with GFP-transduced marrow displayed intense fluorescence. These results show that GFP is an excellent marker for scoring and tracking gene-modified hematopoietic cells and for allowing rapid selection and enrichment of transduced cells expressing high levels of the transgene.

scholarly journals In vivo tumor delivery of the green fluorescent protein gene to report future occurrence of metastasis

2000 ◽  
Vol 7 (10) ◽  
pp. 1336-1340 ◽  
Author(s):  
Satoshi Hasegawa ◽  
Meng Yang ◽  
Takashi Chishima ◽  
Yohei Miyagi ◽  
Hiroshi Shimada ◽  
...  
Keyword(s):  
Green Fluorescent Protein ◽  
Protein Gene ◽  
Fluorescent Protein ◽  
Green Fluorescent Protein Gene ◽  
Tumor Delivery ◽  
Green Fluorescent

scholarly journals Large-scale translocation reversal within the thylakoid Tat system in vivo

2005 ◽  
Vol 171 (2) ◽  
pp. 281-289 ◽  
Author(s):  
Alessandra Di Cola ◽  
Colin Robinson
Keyword(s):  
Large Scale ◽  
Fluorescent Protein ◽  
Intermediate Size ◽  
Processing Site ◽  
Tat System ◽  
Folded Proteins ◽  
Twin Arginine Translocase ◽  
Green Fluorescent

In vitro import assays have shown that the thylakoid twin-arginine translocase (Tat) system transports folded proteins in a unidirectional manner. Here, we expressed a natural substrate, pre-23K, and a 23K presequence–green fluorescent protein (GFP) chimera in vivo in tobacco protoplasts. Both are imported into chloroplasts, targeted to the thylakoids, and processed to the mature size by the lumen-facing processing peptidase. However, the vast majority of mature GFP and about half of the 23K are then returned to the stroma. Mutations in the twin-arginine motif block thylakoid targeting and maturation, confirming an involvement of the Tat apparatus. Mutation of the processing site yields membrane-associated intermediate-size protein in vivo, indicating a delayed reversal of translocation to the stroma and suggesting a longer lived interaction with the Tat machinery. We conclude that, in vivo, the Tat system can reject substrates at a late stage in translocation and on a very large scale, indicating the influence of factors that are absent in reconstitution assays.

scholarly journals H-NS Silences gfp, the Green Fluorescent Protein Gene: gfpTCD Is a Genetically Remastered gfp Gene with Reduced Susceptibility to H-NS-Mediated Transcription Silencing and with Enhanced Translation

2010 ◽  
Vol 192 (18) ◽  
pp. 4790-4793 ◽  
Author(s):  
Colin P. Corcoran ◽  
Andrew D. S. Cameron ◽  
Charles J. Dorman
Keyword(s):  
Green Fluorescent Protein ◽  
Amino Acid ◽  
Amino Acid Sequence ◽  
Reporter Gene ◽  
Protein Gene ◽  
Fluorescent Protein ◽  
Green Fluorescent Protein Gene ◽  
Bacterial Nucleoid ◽  
Green Fluorescent

ABSTRACT The bacterial nucleoid-associated protein H-NS, which preferentially targets and silences A+T-rich genes, binds the ubiquitous reporter gene gfp and dramatically reduces local transcription. We have redesigned gfp to reduce H-NS-mediated transcription silencing and simultaneously improve translation in vivo without altering the amino acid sequence of the GFP protein.

Anti-viral Effects of Superpositively Charged Mutant of Green Fluorescent Protein

2019 ◽  
Vol 26 (12) ◽  
pp. 930-939 ◽  
Author(s):  
Rouhollah Vahabpour ◽  
Parya Basimi ◽  
Farzin Roohvand ◽  
Hassan Asadi ◽  
Gholnaz M. Irani ◽  
...  
Keyword(s):  
High Efficiency ◽  
Fluorescent Protein ◽  
Vero Cells ◽  
Viral Agent ◽  
In Vivo Detection ◽  
E7 Antigen ◽  
Green Fluorescent ◽  
Cellular Immune

Background: Supercharged GFP proteins were known as effective carriers for delivery of macromolecules into eukaryotic cells as well as fluorescent fusion tags for in vitro and in vivo detection. Objective: Herein, anti-viral effects of +36 GFP and its anti-tumor effects were studied in vitro and in vivo, respectively. Methods: We evaluated anti-HIV, anti-HSV, and anti-HCV effects of +36 GFP in vitro using ELISA, and real time PCR as common techniques for their detection, respectively. Moreover, we assessed the role of +36 GFP for eliciting HPV-related anti-tumor effects in mice due to the lack of HPV replication in vitro. Results: Our data showed that +36 GFP efficiently enter the cells and augment the transfection rate of HPV16E7 antigen, as well. Furthermore, +36 GFP significantly reduced HCV, HIV and HSV replication up to 75%, 49% and 43% in HCV-infected Huh7.5 cells, HIV-infected Hela cells and HSV-infected Vero cells, respectively. On the other hand, mice immunization with +36 GFP complexed with HPV16 E7 antigen (+36GFP + E7) or fused to HPV16 E7 antigen (+36GFP-E7) elicited a higher Th1 cellular immune response with the predominant IgG2a, IgG2b, IFN-γ and Granzyme B levels than those induced by other groups. These regimens protected mice against TC- 1 tumor challenge (~ 67%) compared to E7 protein alone (~ 33%). These data suggested that +36 GFP can act as an anti-viral agent at certain dose due to its high efficiency in cell penetration in vitro and in vivo. Conclusion: Generally, +36 GFP targets viral replication in vitro as well as helps to suppress the growth of HPV-related tumors in vivo.

scholarly journals Clathrin exchange during clathrin-mediated endocytosis

2001 ◽  
Vol 155 (2) ◽  
pp. 291-300 ◽  
Author(s):  
Xufeng Wu ◽  
Xiaohong Zhao ◽  
Lauren Baylor ◽  
Shivani Kaushal ◽  
Evan Eisenberg ◽  
...  
Keyword(s):  
Large Scale ◽  
Fluorescent Protein ◽  
Fundamental Property ◽  
Structural Rearrangement ◽  
Coated Pits ◽  
Planar Structures ◽  
Green Fluorescent ◽  
In Vitro Data

During clathrin-mediated endocytosis, clathrin-coated pits invaginate to form clathrin-coated vesicles (CVs). Since clathrin-coated pits are planar structures, whereas CVs are spherical, there must be a structural rearrangement of clathrin as invagination occurs. This could occur through simple addition of clathrin triskelions to the edges of growing clathrin-coated pits with very little exchange occurring between clathrin in the pits and free clathrin in the cytosol, or it could occur through large scale exchange of free and bound clathrin. In the present study, we investigated this question by studying clathrin exchange both in vitro and in vivo. We found that in vitro clathrin in CVs and clathrin baskets do not exchange with free clathrin even in the presence of Hsc70 and ATP where partial uncoating occurs. However, surprisingly FRAP studies on clathrin-coated pits labeled with green fluorescent protein–clathrin light chains in HeLa cells show that even when endocytosis is blocked by expression of a dynamin mutant or depletion of cholesterol from the membrane, replacement of photobleached clathrin in coated pits on the membrane occurs at almost the same rate and magnitude as when endocytosis is occurring. Furthermore, very little of this replacement is due to dissolution of old pits and reformation of new ones; rather, it is caused by a rapid ATP-dependent exchange of clathrin in the pits with free clathrin in the cytosol. On the other hand, consistent with the in vitro data both potassium depletion and hypertonic sucrose, which have been reported to transform clathrin-coated pits into clathrin cages just below the surface of the plasma membrane, not only block endocytosis but also block exchange of clathrin. Taken together, these data show that ATP-dependent exchange of free and bound clathrin is a fundamental property of clathrin-coated pits, but not clathrin baskets, and may be involved in a structural rearrangement of clathrin as clathrin-coated pits invaginate.

scholarly journals Weak but Uniform Enrichment of the Histone Variant macroH2A1 along the Inactive X Chromosome

2008 ◽  
Vol 29 (1) ◽  
pp. 150-156 ◽  
Author(s):  
Flore Mietton ◽  
Aditya K. Sengupta ◽  
Annie Molla ◽  
Gisele Picchi ◽  
Sophie Barral ◽  
...  
Keyword(s):  
X Chromosome ◽  
Genome Stability ◽  
Large Scale ◽  
Fluorescent Protein ◽  
Chromosome Region ◽  
Histone Variant ◽  
Hek 293 ◽  
Tiling Microarrays ◽  
Green Fluorescent

ABSTRACT We studied the enrichment and distribution of the histone variant mH2A1 in the condensed inactive X (Xi) chromosome. By using highly specific antibodies against mH2A1 and stable HEK 293 cell lines expressing either green fluorescent protein (GFP)-mH2A1 or GFP-H2A, we found that the Xi chromosome contains ∼1.5-fold more mH2A1 than the autosomes. To determine the in vivo distribution of mH2A1 along the X chromosome, we used a native chromatin immunoprecipitation-on-chip technique. DNA isolated from mH2A1-immunoprecipitated nucleosomes from either male or female mouse liver were hybridized to tiling microarrays covering 5 kb around most promoters or the entire X chromosome. The data show that mH2A1 is uniformly distributed across the entire Xi chromosome. Interestingly, a stronger mH2A1 enrichment along the pseudoautosomal X chromosome region was observed in both sexes. Our results indicate a potential role for macroH2A in large-scale chromosome structure and genome stability.

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