Mammalian chimaeras / Anne McLaren.

  • McLaren, Anne.
Date:
[1976]
Catalogue details

Licence: Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0)

Credit: Mammalian chimaeras / Anne McLaren. Source: Wellcome Collection.

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    16 Techniques prove unreliable. Weak histocompatibility antigens, such as the male antigen, H-Y, cannot at present be localized by immunofluorescent techniques; strong histocompatibility differences, at the H-2 locus, have been successfully used in some laboratories (Barnes, Holliday & Tuffrey, 1974); perhaps the most valuable application of such techniques so far is in the analysis of inter¬ species chimaeras (Gardner & Johnson, 1973). Biochemical markers Other biochemical variations have also proved valuable. Erythrocyte chi- maerism can be studied using haemoglobin variants (Wegmann & Oilman, 1970) as well as antigenic markers. Serum proteins (e.g. transferrins) can be typed (Pighills, Hancock & Hall, 1968). Genetically determined enzyme variation, detectable by starch or Polyacrylamide gel electrophoresis, has been widely used, particularly with reference to isocitrate dehydrogenase (IDH) and glucose phosphate isomerase (GPI). These enzymes are distributed in most tissues of the body, so with their aid chimaerism can be detected in liver, kidneys, gonads, lungs, heart, spleen, brain, blood (not IDH), skeletal muscle and placenta (both foetal and maternal components). The test for GPI is particularly sensitive, and can detect a minor component at the 1 % level (Chapman, Ansell & McLaren, 1972) using very small amounts of tissue, such as the ectoplacental cones of individual mouse embryos 8 days p.c. (Chapman et al., 1972), or single somites from 10-day embryos (Gearhart & Mintz, \911a). Both IDH and GPI are dimers, so that the presence or absence of a 'hybrid band' on the gel can be used as a test of cell fusion in a chimaeric tissue (Mintz & Baker, 1967; Chapman et al., 1972; Gearhart & Mintz, 1972Ò; Ansell, Barlow & McLaren, 1974). The chief drawback of the electrophoretic approach is that it requires homogenization of the tissues, so that no information can be derived as to the spatial distribution of the chimaera components at the cellular level. This problem could be overcome by the use of histochemical techniques, but so far the only enzyme variation detectable histochemically in the mouse is an activity difference affecting /^-glucuronidase (Condamine, Custer & Mintz, 1971; West, 1976f), and this is of limited usefulness since it appears to be manifest only in the liver (Fig. 7). Liver chimaerism can also be diagnosed in living animals by electrophoresis of urine, using a combination of strains that differ at the Mup-1 locus {major urinary protein) (Baker & Mintz, cited by Condamine et al., 1971). Chromosomal markers Chromosome variations between strains (e.g. translocations) provide a useful and technically straightforward approach to determining the relative pro-