ISSN:
1573-2657
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Medicine
Notes:
Summary The striated muscle tropomyosin-enriched microfilaments were isolated from developing musclesin ovo by the previously described method with a monoclonal antibody against striated muscle isoforms of tropomyosin (Lin & Lin, 1986). Two-dimensional gel analysis of the isolated microfilaments from developing heart, thigh and breast muscles revealed the coexistence of non-muscle isoforms of tropomyosin and actin throughout all stages of embryogenesis. A small but significant amount of skeletal muscle isoforms (α, β) of tropomyosins and their phosphorylated forms was detected in the microfilaments isolated from hearts of 6–15-day-old embryos. These skeletal isoforms of tropomyosins disappeared after this stage of embryogenesis. In addition, we also detected both embryonic and adult isoforms of troponin T in early developing hearts. In developing thigh and breast muscles, the presence of non-muscle tropomyosin isoforms 2, 3a and 3b in the isolated microfilaments was apparent. The contents of tropomyosin isoform 2 were decreased with development and this non-muscle isoform completely disappeared at the 15th day of embryogenesis. On the other hand, the non-muscle tropomyosin isoforms 3a and 3b were present throughout all stages of development. Double-label immunofluorescence microscopy with monoclonal CH1 (anti-striated muscle isoforms of tropomyosin) and CGβ6 (anti-non-muscle isoforms of tropomyosin) on the isolated, glycerinated skeletal and cardiac muscle cells of 10-day-old or 13-day-old embryos confirmed the colocalization of muscle and non-muscle isoforms of tropomyosins within the same cells. These results suggest that different isoforms of actin and tropomyosin can assemble into a class of microfilaments (i.e. striated muscle tropomyosin-enriched microfilaments)in ovo, which may transform into the thin filaments of mature muscle cells.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF01843573
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