Animal cells, fusion

Hybridoma production can be broken down into four processes, immunization of donor animals, cell fusion, cell selection, and expansion. Each of these stages is important for the quality of the final product. Antigens used to immunize animals must be representative of the target substance (see Note 3) or the likelihood of producing cell lines with the correct specificity is remote. Cell... 

The method involves cell fusion, and the resulting permanent cell line is called a hybridoma. Typically, B cells are obtained from the spleen of a mouse (or other suitable animal) previously injected with an antigen or mixture of antigens (eg, foreign cells). The B cells are... 

My hypothesis otherwise remains what it was in 1993 - the epithelial component originated from an epithelial animal and the amoeboid component originated from an amoeboid animal equipped with a protocnidocysts, and possibly already living as an intracellular parasite on the epithelial animal during some stage of its life cycle. One or another device for cell fusion would have to be invoked to explain how an amoeba and an epithelium... 

Spontaneous fusion of cultured cells occurs only rarely. However, the rate at which it happens can be markedly increased by the addition of certain viruses or chemical fusogens to the culture. Sendai virus, as used in early somatic cell fusions, has a lipoprotein envelope similar in structure to the animal cell membrane. It has been suggested that a glycoprotein in the envelope promotes cell fusion by an as yet unexplained mechanism. 

Physical methods of gene transfer. Genes can often be transferred without the use of a cloning vehicle. This is especially important for certain plant cells, such as those of cereal grains, for which transfer of genes via the Ti plasmid has been difficult.167 If DNA, which may be in a plasmid, is coprecipitated with calcium phosphate, it can often be taken up directly either by animal cells or by plant protoplasts.168 169 Polycations also facilitate DNA uptake cationic liposomes seem to be especially effective.170 In the widely used electroporation technique a short electrical pulse of a few hundred volts / cm is applied to create transient pores in the plasma membrane through which the DNA can enter a cell.111 8,171 175 Chromosomes can be transferred by cell fusion and either... 

Membranes of plant and animal cells are typically composed of 40-50 % lipids and 50-60% proteins. There are wide variations in the types of lipids and proteins as well as in their ratios. Arrangements of lipids and proteins in membranes are best considered in terms of the fluid-mosaic model, proposed by Singer and Nicolson % According to this model, the matrix of the membrane (a lipid bilayer composed of phospholipids and glycolipids) incorporates proteins, either on the surface or in the interior, and acts as permeability barrier (Fig. 2). Furthermore, other cellular functions such as recognition, fusion, endocytosis, intercellular interaction, transport, and osmosis are all membrane mediated processes. 

If the immune response is good (see Note 8) rest the animals for a minimum of 8-10 wk before cell fusion work. If the immune response is poor give another immunization on d 61 and assess the circulating antibody level on d 68. 

Antibodies are expressed by hybridoma cells formed by cell fusion of sensitized animal or human B lymphocytes with myeloma cells, or they are generated by EBV (Epstein-Barr virus) transformation of sensitized B lymphocytes. Other heterologous expression systems such as bacteria, yeast, insect cells, and mammalian cells have also been used for expression of antibodies and their fragments. However, because of renaturation problems, glycosylation, and expression levels, mammalian cells are mostly used for the expression of monoclonal antibodies. More recently, technologies have been extensively developed for the expression of antibodies in transgenic animals and transgenic plants. 

Three or four days before carrying out a spleen cell fusion give the chosen animal an iv injection (0.5 mL) of a suspension of DNA/mBSA complex prepared as in Step 2. 

Somatic cell hybrid The cell resulting from the fusion of animal cells derived from somatic cells that differ genetically. 

Since there is an absence of reports detailing the activation of human SCNT oocytes and the successful production of cloned blastocysts, it was necessary to identify several parameters, including the reprogramming time (the time between cell fusion and egg activation, returning the gene expression profile of the somatic cell to that needed for appropriate embryonic development) and activation methods. Based on results from animal SCNT oocytes and the parthenogenetic activation of human oocytes, we initially employed a porcine activation protocol (simultaneous fusion and activation with electrical pulse) which used hu-... 

A EXPERIMENTAL FIGURE 11-43 Fusion proteins from expression vectors demonstrate that the hormone-binding domain of the glucocorticoid receptor (GR) mediates translocation to the nucleus in the presence of hormone. Cultured animal cells were transfected with expression vectors encoding the proteins diagrammed at the bottom. Immunofluorescence with a labeled antibody specific for p-galactosidase was used to detect the expressed proteins in transfected cells, (a) In cells that expressed p-galactosidase alone, the enzyme... 

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