Accumulation and localization of troponin-T in developing hearts of Ambystoma mexicanum.
Troponin-T (Tn-T) expression in developing hearts of axolotls, Ambystoma mexicanum, was studied with the use of polyclonal and monoclonal antibodies and SDS-polyacrylamide gel electrophoresis. In precontractile hearts (stage 32/33), Tn-T was present in addition to myosin, actin and tropomyosin as evidenced by the presence of the protein bands in SDS-gels and by indirect immunofluorescence. Tn-T was localized in amorphous collections at the peripheries of these precontractile cells. Hearts of normal and cardiac lethal mutant siblings were also analysed for Tn-T expression. No detectable differences in the quantity of protein present was observed by gel electrophoresis or by indirect immuno-fluorescence. The most striking difference concerned the localization of the protein. In normal hearts, Tn-T was primarily localized in the I-bands of organized myofibrils; however, in mutant cells the Tn-T was localized in amorphous collections at the cell peripheries suggesting a reduction of myofibrillar organization in these cells. No differences were observed in the contractile protein composition between normal and mutant embryonic hearts by gel electrophoresis experiments.
D000199:Actins / Q000032:analysis; D000557:Ambystoma / Q000196:embryology*; D000558:Ambystoma mexicanum / Q000196:embryology*; D000818:Animals; D000911:Antibodies, Monoclonal; D004591:Electrophoresis, Polyacrylamide Gel; D005455:Fluorescent Antibody Technique; D006321:Heart / Q000196:embryology*; D006330:Heart Defects, Congenital / Q000196:embryology / Q000378:metabolism; D005779:Immunodiffusion; D008856:Microscopy, Fluorescence; D009206:Myocardium / Q000737:chemistry*; D009210:Myofibrils / Q000737:chemistry; D014335:Tropomyosin / Q000032:analysis; D014336:Troponin / Q000032:analysis*; D020107:Troponin T
D000199:Actins; D000911:Antibodies, Monoclonal; D014335:Tropomyosin; D014336:Troponin; D020107:Troponin T