Ciona Troponin I gene expression. (a–h) Expression of Troponin I transcript as determined by in situ hybridization. Expression is weak as early as gastrulation(a), is very strong by initial tailbud (b), and continues in the muscle through mid-tailbud (c), late tailbud (d), tadpole (e), and juvenile stages (f–h). Note the expression in the trunk ventral cells (TVC; adult heart precursors), during the late tailbud stage in e. (i–n) Expression of lacZ reporter construct tn.pro.1793 as determined by X-gal staining. Expression is strong in mid tailbud (i,j), and continues through late tailbud (k), early tadpole (l), and juvenile stages (m). Ectopic expression in the mesenchyme is common (arrowhead, i). Expression continues in the tail muscle from the late tailbud (k) to the early tadpole (l). Expression also occurs in the TVC (arrowhead, m) and juvenile heart (arrowhead, n).
