Fig. 5

Stable clonal growth of muscle perdures throughout life. (A,B) Single 8-month-old, adult Musclebow2-marked fish that were heat-shocked for 5 min at 37°C at 30% epiboly show distinct patterns of EYFP-marked myotomes on left and right side and between epaxial and hypaxial somite (A). When the right side of the same fish was imaged for all four fluorescent proteins, this fish had faint tdT throughout muscle and RFP in lens, indicating Cre expression, that had triggered clonal marking of several half somites in either EYFP or mCer. Asterisks indicate background blue autofluorescence from xanthophores. Box, magnified in inset, shows regions of hypaxial myotomes 11 and 14 marked by EYFP, whereas a region of somite 15 near the HZM is marked by mCer only. In a similar region of myotome 14, muscle is marked by both mCer and EYFP. (C-E) Eight-month-old adult Musclebow2-marked BB3mus7 siblings (C) that were heat shocked for 5 min at 39°C at 24 hpf. Note the similar size but lower frequency of mCer clones compared to EYFP clones in Fish 6. Boxed region, magnified in D, reveals layers of fibres with distinct orientations (fibre ends indicated by pairs of arrowheads) and individual marked fibres (arrows). Ventral view of pectoral fin region of Fish 6 (E). (F) Fish 1 from C at 15 and 32 months of age showing similar clonal pattern. Numbered boxes are magnified at right. Scale bar: 50 µm.