Development of a cell wash buffer that minimizes nucleic acid loss from Clostridium perfringens 10543 A

1985 ◽  
Vol 31 (6) ◽  
pp. 575-578
Author(s):  
Hans P. Blaschek ◽  
Michael A. Klacik
Keyword(s):  
Nucleic Acid ◽  
Clostridium Perfringens ◽  
Sucrose Concentration ◽  
Wash Temperature ◽  
Wash Buffer ◽  
A Cell ◽  
Autolytic Activity

Autolytic activity and nucleic loss from Clostridium perfringens 10543 A was demonstrated during successive cell washes in hypotonic TES buffer. Autolysis increased nearly sixfold and nucleic acid loss nearly twofold when 10 mM EDTA was added to 0.3 M Tris–sucrose buffer. Attempts to minimize both autolysis and nucleic acid loss from C. perfringens during routine washing steps were unsuccessful when the effects of sucrose concentration, pH, CaCl2 addition, or wash temperature were examined independently. However, autolytic activity was eliminated and nucleic acid loss reduced to less than 5% when C. perfringens cells were washed at 4 or 25 °C in 1.0 M sucrose, 50 mM Tris–HCl, and 25 mM CaCl2 at pH 5.7.

scholarly journals Hybrid-Type SELEX for the Selection of Artificial Nucleic Acid Aptamers Exhibiting Cell Internalization Activity

Pharmaceutics ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 888
Author(s):  
Hiro Uemachi ◽  
Yuuya Kasahara ◽  
Keisuke Tanaka ◽  
Takumi Okuda ◽  
Yoshihiro Yoneda ◽  
...  
Keyword(s):  
Nucleic Acid ◽  
Surface Protein ◽  
Functional Screening ◽  
Nucleic Acid Aptamers ◽  
Hybrid Type ◽  
Cell Internalization ◽  
Promising Target ◽  
A Cell ◽  
Exponential Enrichment

Nucleic acid aptamers have attracted considerable attention as next-generation pharmaceutical agents and delivery vehicles for small molecule drugs and therapeutic oligonucleotides. Chemical modification is an effective approach for improving the functionality of aptamers. However, the process of selecting appropriately modified aptamers is laborious because of many possible modification patterns. Here, we describe a hybrid-type systematic evolution of ligands by exponential enrichment (SELEX) approach for the generation of the artificial nucleic acid aptamers effective against human TROP2, a cell surface protein identified by drug discovery as a promising target for cancer therapy. Capillary electrophoresis SELEX was used for the pre-screening of multiple modified nucleic acid libraries and enrichment of TROP2 binding aptamers in the first step, followed by functional screening using cell-SELEX in the second step for the generation of cell-internalizing aptamers. One representative aptamer, Tac-B1, had a nanomolar-level affinity to human TROP2 and exhibited elevated capacity for internalization by cells. Because of the growing interest in the application of aptamers for drug delivery, our hybrid selection approach has great potential for the generation of functional artificial nucleic acid aptamers with ideal modification patterns in vitro.

Electron microscopy of the replicative events of A25 bacteriophages in group A streptococci

1972 ◽  
Vol 18 (1) ◽  
pp. 93-96 ◽  
Author(s):  
S. E. Read ◽  
R. W. Reed
Keyword(s):  
Electron Microscopy ◽  
Cell Wall ◽  
Electron Microscope ◽  
Nucleic Acid ◽  
Group A Streptococcus ◽  
Group A Streptococci ◽  
Virulent Phage ◽  
Acid Pool ◽  
Group A ◽  
A Cell

The replicative events of a virulent phage (A25) infection of a group A Streptococcus (T253) were studied using the electron microscope. The first intracellular evidence of phage replication in a cell occurred 30 min after infection with arrest of cell division and increase in the nucleic acid pool. Phage heads were evident in the nucleic acid pool of the cells 45 min after infection. Release of phages occurred by splitting of the cell wall along discrete lines. This appeared to be at sites of active wall synthesis, i.e., near the region of septum formation. Many phage components were released but relatively few complete phages indicating a relatively inefficient replicative system.

scholarly journals Inverted sugar syrup attained from sucrose hydrolysis using a membrane reactor

2010 ◽  
Vol 46 (3) ◽  
pp. 571-577 ◽  
Author(s):  
Ester Junko Tomotani ◽  
Michele Vitolo
Keyword(s):  
Membrane Reactor ◽  
Feeding Rate ◽  
Sucrose Solution ◽  
Sucrose Concentration ◽  
Sucrose Hydrolysis ◽  
Variable Parameters ◽  
Sugar Syrup ◽  
State Duration ◽  
Styrene Divinylbenzene ◽  
A Cell

Invertase, whether adsorbed on styrene-divinylbenzene copolymers or otherwise, was used for continuous sucrose hydrolysis using a cell-type membrane reactor (CTMR), coupled with an ultra (UF-100kDa), or a microfiltration (MF- pore diameter of 5 µm) membrane. In all tests, the pH (5.5), temperature (30 ºC), reaction volume (10 mL) and agitation (100 rpm) were set constant; whereas, variable parameters were: feeding rate (0.4, 0.8 and 1.6 h-1), inlet sucrose concentration (2.5, 6.5, 50 and 100 mM) and enzyme/resin ratio (1.64 mg or 3.28 mg of protein per 25, 50 or 100 mg of resin). The best result (yield of 100%, steady-state duration over 20h and specific reaction rate over 243 x 10-3 mmol/h.mE) was obtained when insoluble invertase (1.64 mg protein/100 mg resin) was used to convert 50 mM or 100 mM of sucrose solution at 0.4 h-1 using a UF-CTMR.

scholarly journals Detergent-Resistant Membrane Microdomains Facilitate Ib Oligomer Formation and Biological Activity of Clostridium perfringens Iota-Toxin

2004 ◽  
Vol 72 (4) ◽  
pp. 2186-2193 ◽  
Author(s):  
Martha L. Hale ◽  
Jean-Christophe Marvaud ◽  
Michel R. Popoff ◽  
Bradley G. Stiles
Keyword(s):  
Clostridium Perfringens ◽  
Cell Types ◽  
Cell Receptor ◽  
Vero Cells ◽  
Membrane Microdomains ◽  
Oligomer Formation ◽  
A Cell ◽  
Clostridium Perfringens Iota Toxin ◽  
Detergent Resistant Membrane ◽  
Soluble Fractions

ABSTRACT Clostridium perfringens iota-toxin consists of two separate proteins identified as a cell binding protein, iota b (Ib), which forms high-molecular-weight complexes on cells generating Na+/K+-permeable pores through which iota a (Ia), an ADP-ribosyltransferase, presumably enters the cytosol. Identity of the cell receptor and membrane domains involved in Ib binding, oligomer formation, and internalization is currently unknown. In this study, Vero (toxin-sensitive) and MRC-5 (toxin-resistant) cells were incubated with Ib, after which detergent-resistant membrane microdomains (DRMs) were extracted with cold Triton X-100. Western blotting revealed that Ib oligomers localized in DRMs extracted from Vero, but not MRC-5, cells while monomeric Ib was detected in the detergent-soluble fractions of both cell types. The Ib protoxin, previously shown to bind Vero cells but not form oligomers or induce cytotoxicity, was detected only in the soluble fractions. Vero cells pretreated with phosphatidylinositol-specific phospholipase C before addition of Ib indicated that glycosylphosphatidyl inositol-anchored proteins were minimally involved in Ib binding or oligomer formation. While pretreatment of Vero cells with filipin (which sequesters cholesterol) had no effect, methyl-β-cyclodextrin (which extracts cholesterol) reduced Ib binding and oligomer formation and delayed iota-toxin cytotoxicity. These studies showed that iota-toxin exploits DRMs for oligomer formation to intoxicate cells.

scholarly journals Clostridium perfringens iota toxin: characterization of the cell-associated iota b complex

2002 ◽  
Vol 367 (3) ◽  
pp. 801-808 ◽  
Author(s):  
Bradley G. STILES ◽  
Martha L. HALE ◽  
Jean Christophe MARVAUD ◽  
Michel R. POPOFF
Keyword(s):  
Cell Surface ◽  
Molecular Mass ◽  
Clostridium Perfringens ◽  
Surface Protein ◽  
Protein S ◽  
Vero Cells ◽  
Resistant Cell ◽  
Resistant Cell Line ◽  
Neutralizing Monoclonal Antibody ◽  
A Cell

Clostridium perfringens type E iota toxin consists of two unlinked proteins designated as iota a (Ia; molecular mass47kDa), an ADP-ribosyltransferase and iota b (Ib; molecular mass81kDa) which binds to the cell surface and facilitates Ia entry into the cytosol. By Western-blot analysis, Ib incubated with Vero cells at 37°C generated a cell-associated, SDS-insoluble oligomer of Ib (molecular mass>220kDa) within 15s, which was still evident 110min after washing cells. Ib oligomerization was temperature, but not pH, dependent and was facilitated by a cell-surface protein(s). Within 5min at 37°C, cell-bound Ib generated Na+/K+ permeable channels that were blocked by Ia. However, Ib-induced channels or oligomers were not formed at 4°C. Two monoclonal antibodies raised against Ib that recognize unique, neutralizing epitopes within residues 632—655 either inhibited Ib binding to cells and/or oligomerization, unlike a non-neutralizing monoclonal antibody that binds within Ib residues 28—66. The Ib protoxin (molecular mass98kDa), which does not facilitate iota cytotoxicity but binds to Vero cells, did not oligomerize or form ion-permeable channels on cells, and neither trypsin nor chymotrypsin treatment of cell-bound Ib protoxin induced large complex formation. The link between Ib oligomers and iota toxicity was also apparent with a resistant cell line (MRC-5), which bound to Ib with no evidence of oligomerization. Overall, these studies revealed that the biological activity of iota toxin is dependent on a long-lived, cell-associated Ib complex that rapidly forms ion-permeable channels in cell membranes. These results further reveal the similarities of C. perfringens iota toxin with other bacterial binary toxins produced by Bacillus anthracis and C. botulinum.

scholarly journals Live cell PNA labelling enables erasable fluorescence imaging of membrane proteins

2020 ◽  
Author(s):  
Georgina C. Gavins ◽  
Katharina Gröger ◽  
Michael D. Bartoschek ◽  
Philipp Wolf ◽  
Annette G. Beck-Sickinger ◽  
...  
Keyword(s):  
Nucleic Acid ◽  
Cho Cells ◽  
Fluorescent Dyes ◽  
Coiled Coil ◽  
Dna Nanotechnology ◽  
Nucleic Acid Hybridization ◽  
Landing Platform ◽  
Acid Protein ◽  
Reaction Proceeds ◽  
A Cell

AbstractDNA nanotechnology is an emerging field, which promises fascinating opportunities for the manipulation and imaging of proteins on a cell surface. The key to progress in the area is the ability to create the nucleic acid-protein junction in the context of living cells. Here we report a covalent labelling reaction, which installs a biostable peptide nucleic acid (PNA) tag. The reaction proceeds within minutes and is specific for proteins carrying a 2 kDa coiled coil peptide tag. Once installed the PNA label serves as a generic landing platform that enables the recruitment of fluorescent dyes via nucleic acid hybridization. We demonstrate the versatility of this approach by recruiting different fluorophores, assembling multiple fluorophores for increased brightness, and achieving reversible labelling by way of toehold mediated strand displacement. Additionally, we show that labelling can be carried out using two different coiled coil systems, with EGFR and ETBR, on both HEK293 and CHO cells. Finally, we apply the method to monitor internalization of EGFR on CHO cells.

Introduction to the Principles of Virology

2020 ◽  
pp. 11-22
Author(s):  
Michael B. A. Oldstone
Keyword(s):  
Nucleic Acid ◽  
Nobel Prize ◽  
Viral Protein ◽  
Living Cell ◽  
Cell Walls ◽  
Severity Of Illness ◽  
Cell Receptor ◽  
The Body ◽  
Bad News ◽  
A Cell

This chapter defines what a virus is, how it replicates, and how it causes diseases. Peter Medawar, a biologist awarded the Nobel Prize for Medicine and Physiology in 1960, defined viruses as a piece of nucleic acid surrounded by bad news. Viruses cannot multiply until they invade a living cell. However, viruses can enter all cellular forms of life from plants and animals to bacteria, fungi, and protozoa. As opposed to plants and animals, which are made up of cells, viruses lack cell walls and are therefore obligatory parasites that depend for replication on the cells they infect. The attachment or binding of a viral protein to a cell receptor is the first step that initiates infection of a cell. The type of cells with such receptors and/or with the ability to replicate a given virus often determines the severity of illness that a virus can cause, the distribution of areas in the body that can be affected, and the host’s potential for recovery.

scholarly journals Diagnostic Accuracy of Nucleic Acid Amplification-Based Assays for Clostridium perfringens-Associated Diseases: a Systematic Review and Meta-analysis

2020 ◽  
Vol 58 (9) ◽  
Author(s):  
Ke Chen ◽  
Sarfraz Ahmed ◽  
Yun-Juan Sheng ◽  
Changfeng Sun ◽  
Cun-Liang Deng ◽  
...  
Keyword(s):  
Nucleic Acid ◽  
Diagnostic Accuracy ◽  
Likelihood Ratio ◽  
Clostridium Perfringens ◽  
Meta Analysis ◽  
Reference Standards ◽  
Nucleic Acid Amplification ◽  
Content Type ◽  
Microbiological Culture ◽  
Associated Diseases

ABSTRACT Timely and accurate methods for detecting Clostridium perfringens-associated diseases (CPAD) are crucial to improve patient care. A number of studies have evaluated the accuracy of nucleic acid amplification tests (NAAT) in detecting CPAD, but decisive results about their effectiveness have not been reported. We conducted a meta-analysis to evaluate the diagnostic performance of NAAT for detecting C. perfringens in clinical diarrheal samples. Five databases including PubMed, Embase, Scopus, Web of Science, and the Cochrane library were systematically probed for studies published before 6 December 2019. From 2,632 citations, we identified five eligible studies comprising 817 samples. Three studies (n = 695 samples) compared NAAT with a microbiological culture while the other three studies (n = 322 samples) compared NAAT with an immunoassay. NAAT revealed higher diagnostic accuracy against immunoassay (sensitivity, 0.53 [95% confidence interval [CI], 0.35 to 0.7]; specificity, 0.97 [95% CI, 0.95 to 0.99]; positive likelihood ratio [PLR], 23.2 [95% CI, 3.49 to 153.98]; negative likelihood ratio [NLR], 0.25 [95% CI, 0 to 245.28]; diagnostic odds ratio [DOR], 74.11 [95% CI, 2.11 to 2,593.7]) than microbiological culture (sensitivity, 0.31 [95% CI, 0.22 to 0.41]; specificity, 0.95 [95% CI, 0.93 to 0.97]; PLR, 11.56 [95% CI, 3.87 to 34.6]; NLR, 0.57 [95% CI, 0.27 to 1.21]; DOR, 18.1 [95% CI, 4.83 to 67.8]). NAAT pooled specificity was consistently ≥95% against that of applied reference standards. A meta-regression and subgroup analysis of sample condition, gene target, study design, and reference standards could not explain the heterogeneity (P > 0.05) in the diagnostic efficiency. The analysis has demonstrated that the diagnostic accuracy of NAAT is relatively insufficient to replace traditional reference standards as a single diagnostic test. NAAT can be applied in combination with microbiological culture because of the advantage of time to result and in scenarios where traditional tests are not feasible. Further investigations in this direction with larger sample sizes are still warranted to support our findings.

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