Improve Research Reproducibility A Bio-protocol resource
- Submit a Protocol
- Receive Our Alerts
- EN
- Protocols
- Articles and Issues
- For Authors
- About
- Become a Reviewer
Past Issue in 2014
Volume: 4, Issue: 9
Cancer Biology
Transwell Co-culture of Bone Marrow Macrophages with Tumor Cells
Bone is a primary site of metastasis from prostate and breast cancers. Bone marrow macrophages (BMMs) are mediators of inflammatory processes and are thought to promote tumor growth in the skeletal sites. In order to elucidate how their interactions with tumor cells impact aggressiveness of metastatic tumors in bone in vitro methods are required. By employing a system in which BMMs and tumor cells are grown separately, yet share the media and exchange soluble factors, contribution of each cell type in the context of BMM-tumor cell relationship in the bone marrow can be investigated. Additional advantages of this system include the ability to study: 1) phenotypic changes in BMMs and tumor cells upon co-culture; 2) cell-specific modulation of protein and gene expression; and 3) effects on proliferation and cell survival. It is noteworthy, that this transwell co-culture system is not limited to BMMs and tumor cells and can be easily modified to include other components of bone marrow microenvironment (e.g., adipocytes, stromal cells, osteoblasts).
Immunostaining Protocol: P-Stat3 (Xenograft and Mice)
We sought to understand the mechanisms behind the potent effect of stromal TGF-beta program on the capacity of colorectal cancer (CRC) cells to initiate metastasis. We discovered that mice subcutaneous tumors and metastases generated in the context of a TGF-beta activated microenvironment displayed prominent accumulation of p-STAT3 in CRC cells compared with those derived from control cells. STAT3 signaling depended on GP130 as shown by strong reduction of epithelial p STAT3 levels upon GP130 shRNA-mediated knockdown in CRC cells.
Detection of Tumor Cell Surface-reactive Antibodies
Vaccine-based immunotherapy is being used to treat dogs with primary brain tumors. The vaccines are composed of a lysate of autologous tumor cells, which stimulate an immune response producing tumor specific antibodies that are capable of inducing antibody-dependent cell-mediated cytotoxicity to allogeneic, as well as autologous, tumor cells. This protocol will describe the tumor cell serum antibody-binding assay to measure the tumor-reactive IgG antibody response. Key features of this assay are that it is performed with sera collected from the canine patient prior to and following vaccination as the source of antibodies and canine brain tumor cells used as the target cells.
Immunostaining Protocol: P-Smad2 (Xenograft and Mice)
Metastasis depends on a gene program expressed by the tumor microenvironment upon TGF-beta stimulation. CRC (Colorectal cancer) cell lines did not induce robust stromal TGF-beta responses when injected into nude mice as shown by lack of p-SMAD2 accumulation in tumor-associated stromal cells. To enforce high TGF-beta signaling in xenografts, we engineered CRC cell lines to secrete active TGF-beta. Subcutaneous tumors obtained from HT29-M6TGF-β, KM12L4aTGF-β cells and SW48TGF-β cells contained abundant p-SMAD2+ stromal cells.
Microbiology
Enterovirus 71 Virus Propagation and Purification
Since its discovery in 1969, enterovirus 71 (EV71) has emerged as a serious worldwide health threat. This member of the picornavirus family causes hand, foot, and mouth disease, and also has the capacity to invade the central nervous system to cause severe disease and death. This is the propagation and purification procedure to produce infectious virion.
Minimal Bactericidal Concentration for Biofilms (MBC-B)
A biofilm is a multicellular consortium of surface associated microbes surrounded by a hydrated, extracellular polymer matrix. The biofilm matrix plays a critical role in preventing desiccation, acquiring nutrients, and provides community protection from environmental assaults. Importantly, biofilms are significantly more resistant to antimicrobials relative to their free-swimming counterparts. The level of antimicrobial tolerance is influenced by a number of factors, including genetic/adaptive resistance mechanisms, stage of biofilm development, and pharmacokinetics of the antibiotic. Here, we describe an in vitro microtiter-based assay to quantify the minimal bactericidal concentration for biofilms (MBC-B) for short exposure times (2 h). This exposure period is significantly shorter than standard over-night and 24-hour treatments described in traditional protocols. This assay was developed to approximate the time an antibiotic is available during a one-time treatment before it is metabolized, sequestered by host proteins, or digested.
Microfluidic-based Time-kill Kinetic Assay
In many environments, bacteria favor a sessile, surface-attached community lifestyle. These communities, termed biofilms, are ubiquitous among many species of bacteria. In some cases, biofilms form under flow conditions. Flow chambers, and in particular microfluidic channels, can be used to observe biofilm development and physiological effects while varying nutrient conditions, flow velocities, or introducing antimicrobials to the biofilm in real time. Here, we describe a microfluidic-based kill-kinetics assay for the observation of antimicrobial effects on biofilms under flowing conditions.
ELISA for Alpha-hemolysin (Hla) in Methicilin-resistant Staphylococcus aureus (MRSA)
Anti-virulence agents against MRSA inhibit the production of disease-causing virulence factors, such as alpha-hemolysin, but are neither bacteriostatic nor bactericidal. Here we discuss a rapid method to screen for MRSA anti-virulence agents by measuring alpha-hemolysin production through ELISA. This protocol can be used with other alpha-hemolysin producing bacteria or for other excreted toxins to which antibodies exist.
Extraction and Quantification of Poly P, Poly P Analysis by Urea-PAGE
Inorganic polyphosphate (poly P) molecules, linear chains containing hundreds of orthophosphate (Pi) residues linked by high-energy phosphoanhydride bonds are abundant in every cell in nature. These molecules are widely distributed among bacteria, including key pathogens, and eukaryotes, poly P is present in organelles, including nuclei, mitochondria, and vesicles.Remarkable properties of this molecule as a polyanion have been discovered and have made it suited for a crucial role in the emergence of cells on earth. Poly P is essential for bacterial responses to stresses and starvation, motility, quorum sensing, biofilm formation, and virulence and essential for survival. Polymers of different lengths are present in different locations and have different roles in the cell.
Amino Acid Racemase Enzyme Assays
Amino acid racemases are enzymes that invert the α-carbon stereochemistry of amino acids (AAs), interconverting amino acids between their L- and D-enantiomers in a reversible reaction. In bacteria, they are known to have catabolic physiological functions but are also involved in the synthesis of many D-AAs, including D-glutamate and D-alanine, which are necessary components of the peptidoglycan layer of the bacterial cell wall. As such, amino acid racemases represent significant targets for the development of bactericidal compounds. Amino acid racemases are also regarded by the biotechnological industry as important catalysts for the production of economically relevant D-AAs. Here, we provide a detailed protocol using high performance liquid chromatography (HPLC) and 1-fluoro-2,4-dinitrophenyl-5-L-alanine amide (FDAA, also Marfey’s reagent) for the characterization of novel amino acid racemases. The protocol described here was designed to obtain accurate kinetic parameters (kcat, KM values). Enzyme concentrations and reaction times were optimized so as to minimize the reverse reaction, which can confound results when measuring racemase reactions.
In vitro Analysis for Macrophage Binding and Pro-inflammatory Responses to Candida albicans
Macrophage recognition of Candida albicans (C. albicans) is facilitated by pattern recognition receptors that interact with the fungal pathogen associated molecular patterns (PAMPs). Dectin-1 is the major macrophage receptor that is known to recognize fungal Beta-glucans leading to induction of various immune responses. This receptor is also known to be required for in vivo protection against C. albicans (Taylor et al., 2007). We recently showed that the Dectin-1 mediated protection in vivo is strain-dependent, and that C. albicans can adapt to modulate immune recognition by Dectin-1 (Marakalala et al., 2013). In vitro analysis, however, showed a Dectin-1-dependent and pro-inflammatory responses against all strains tested. This protocol describes in detail the in vitro analysis used in the paper. In particular, methods involved in fluorescent labeling of live C. albicans, quantification of macrophage binding of the pathogen, and pro-inflammatory responses to yeast and hyphal forms of the fungi are described.
Plant Science
Extraction and Measurement the Activities of Cytosolic Phosphoenolpyruvate Carboxykinase (PEPCK) and Plastidic NADP-dependent Malic Enzyme (ME) on Tomato (Solanum lycopersicum)
A recent study demonstrated that cytosolic phosphoenolpyruvate carboxykinase (PEPCK) and NADP-malic enzyme (NADP-ME) have an important role in malate metabolism during fruit ripening (Osorio et al., 2013). PEPCK catalyze the ATP-dependent decarboxylation of oxaloacetate (OAA) to phosphoenolpyruvate (PEP) and NADP-ME, the reversible conversion of malate and pyruvate. Here, we present the detailed protocols to measure PEPCK activity in carboxylation direction by following oxidation of NADH and to measure NADP-ME activity based upon the reduction of NADP+.