Cell hybridization techniques

Lebaron, P. Catala, P. Fajon, C. Joux, F. Baudart, J. Bernard, L. A new sensitive, whole-cell hybridization technique for detection of bacteria involving a biotinylated oligonucleotide probe targeting rRNA and tyramide signal amplification. Appl. Environ. Microbiol. 1997, 63, 3274-3278. 

Omalizumab is a monoclonal antibody developed through somatic cell hybridization techniques and was identified as a murine anti-human IgE antibody, originally called MAE11 (48). It is designed to interact with the site that binds to FceRI on mast cells. Additional amino acid sequences have been incorporated into the antibody so that a humanized product resulted that only differs by 5% nonhuman amino acid residues. 

The development of cell hybridization techniques has greatly extended the information on genetic linkage obtainable by family studies, and has resulted in the assignment of numerous biochemical markers to specific chromosomes. Since with few exceptions we do not yet understand disorders of keratinization in enzymatic terms, and have no abnormalities reliably identifiable in cultured cells, this approach has not yet been exploited directly in the ichthyoses and related disorders, but is likely to prove extremely valuable once primary biochemical abnormalities are found. 

The basic scheme of this algorithm is similar to cell-to-cell mapping techniques [14] but differs substantially In one important aspect If applied to larger problems, a direct cell-to-cell approach quickly leads to tremendous computational effort. Only a proper exploitation of the multi-level structure of the subdivision algorithm (also for the eigenvalue problem) may allow for application to molecules of real chemical interest. But even this more sophisticated approach suffers from combinatorial explosion already for moderate size molecules. In a next stage of development [19] this restriction will be circumvented using certain hybrid Monte-Carlo methods. 

McFadden G. In situ hybridization techniques molecular cytology goes ultrastruc-tural, in Electron Microscopy of Plant Cells (Hall J, Hawes C, eds.), Academic Press, London, 1991, pp. 219-255. 

In situ hybridization (ISH) consists of the application of hybridization techniques to intact cells which demonstrate genetic information within a morphologic context. This technology takes advantage of the hybridization properties of nucleic acids and offers a distinct technique to directly analyze sequence information in intact tissues. In essence, it combines cytogenetic techniques with molecular biology to probe gene alterations at molecular levels. Development of... 

Immunocytochemistry and in situ hybridization techniques were used to detect HIV-1 infected cells in the testis (P5), excurrent ducts, and prostate. Distinct pathologic changes were observed in the majority of testis of AIDS patients that included azoospermia, hyalinization of the boundary wall of seminiferous tubules, and lymphocytic infiltration of the interstitium. In the testis, many white blood cells were shown to the CD4 + HIV-1 positive cells of lymphocy-tic/monocytic morphology, found in the seminiferous tubules and interstitium of the testis, epididymal epithelium, and connective tissue of the epididymis and prostate. There was no evidence of active HIV-1 infection in germ cells or Sertoli cells of the seminiferous tubules or other epithelial cells lining the excurrent ducts or prostatic glands. 

If cellular localization of the antigen-antibody complex is not required, enzyme immunolabeling can be performed on cells adherent to a microtiter plate, and the color change resulting from the enzymatic reaction can be detected as a change in absorbance with an automatic plate reader (see Chapter 28). Biotinylation of antibodies and the use of the avidin-biotin complex has further extended the versatility and sensitivity of the enzymatic techniques (see Chapters 7 and 25-27). Most recently, the principles behind these techniques have been applied in combination with in situ hybridization techniques. Using nucleic acid-antibody complexes as probes, specific DNA or RNA sequences can be localized (see Chapters 46 9). 

The hybrid is able to produce more alkaloids than the basic callus, which is an undifferentiated mass of cells. Alkaloid production in cell cultures can be more successful with the immobihzation of plant cells and enzymes and by using bioreactor systems . Alkaloid produced in cell cultures can be isolated directly from this culture or from young plants grown from this culture. More than 250 alkaloids are reported to be produced by cell-culture techniques. Only a limited number of species have been researched in this respect. The species studied are known to produce alkaloids with special use in applications. The most researched alkaloids produced by cell cultures are mentioned in Table 25. 

Fig. 4. In situ hybridization technique. Part of an erythroid precursor cell infected with the human parvovirus B19 and probed for viral DNA. The BI9 nucleic acid is located within the centra electron lucent area of the nucleus (N) and also at nuclear pores (arrowheads). Ch, chromatin M, mitochondrion. A three-step detection protocol was used (see ref. 5 for details). Sheep antidigoxigenin followed by rabbit antisheep Ig and then goat antirabbit Ig conjugated to 10-nm gold. Bar is 0.5 pm.

In most insects, pheromones are synthesized in specialized cells or tissues associated with the epidermis (Tillman et al., 1999). Biochemical analyses traced the localization of Scolytid pheromone accumulation to portions of the alimentary canal, particularly the hindgut (e.g. Borden et al., 1969 Byers, 1983), but the actual tissue source of pheromone components was unknown. Fortunately, the tight correlation of HMG-R gene expression with pheromone component biosynthesis meant that hybridization techniques could be used to map the location of pheromone biosynthesis. Northern blots provided the first maps, while in situ hybridizations definitively showed which tissues were elevating HMG-R mRNA in response to feeding or JH III treatment. As with endocrine regulation studies, the molecular and biochemical data complemented each other. 

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