Histological distribution and developmental changes of tropomyosin isoforms in three chicken digestive organs

Histological localization of tropomyosin isoforms in three digestive organs from embryonic and adult chickens was performed by using rabbit antisera against chicken skeletal muscle tropomyosin and against low-Mr-type tropomyosin from chicken small intestine mucosa. The former antiserum (named TM-SH) reacted with alpha, beta, and high-Mr-type isoforms, and the latter (named TM-HL) reacted with alpha, beta, high-Mr-type and low-Mr-type isoforms, alpha and beta Isoforms were detected in muscle cells of the muscular layer and the muscularis mucosa. Low-Mr-type isoforms, however, were detected along the cell membrane and cytoplasm of almost all nonmuscle cells, especially in terminal webs of epithelial cells. Developmental changes of tropomyosin isoforms in digestive organs were studied by two-dimensional gel electrophoresis and image analysis. The relative amounts of alpha and beta isoforms increased in the course of development, but those of low-Mr-type and high-Mr-type isoforms decreased.