Fig 4. Cardiomyocytes do not re-connect after transient reduction of Talin function.

In a wildtype adult, 6 days after eclosion, phalloidin labeled contractile fibres encompassed the entire heart, and integrin concentrated at cell insertions and the midline (arrowhead, A). This morphology was not altered after a further 6 weeks of aging (arrowhead, F). Talin was transiently depleted during larval, pupal or adult stages as shown by the coloured schema at the bottom of each panel, and stages labeled in (A). UAS-talin RNAi; Hand-Gal4, tub- Gal80 ^ts flies were at 18°C during grey timeline, and Talin levels were normal., Hearts express the RNAi transgene, and deplete Talin levels at 29°C during the green timeline. Depletion during L1 created large gaps in myofibril coverage seen in the adult (B). Depletion during L2 created small gaps, filled with a broadened zone of integrin adhesion to the heart ECM (C). Depletion during pupal stages only generated an intermediate phenotype (D), comparable to depletion during L2, L3 and pupal stages combined (E). Depletion of Talin for 6 weeks of adulthood triggered small changes in the width of integrin labeled insertions (G). In contrast, gaps triggered in L2 persisted in 6 week old adults (H). Confocal projections of immunolabled adult heart dissections.