The molecular mechanisms regulating animal tissue size during development are unclear. This question has been extensively studied in the Drosophila wing disc. Although cell growth is regulated by the kinase TORC1, no readout exists to visualize TORC1 activity in situ in Drosophila. Both the cell cycle and the morphogen Dpp are linked to tissue growth, but whether they regulate TORC1 activity is not known. We develop here an anti-phospho-dRpS6 antibody that detects TORC1 activity in situ. We find, unexpectedly, that TORC1 activity in the wing disc is patchy. This is caused by elevated TORC1 activity at the cell cycle G/S transition due to CycD/Cdk4 phosphorylating TSC1/2. We find that TORC1 is also activated independently of CycD/Cdk4 when cells with different levels of Dpp signaling or Brinker protein are juxtaposed. We thereby characterize the spatial distribution of TORC1 activity in a developing organ.

This article examines the development of the Leningrad subway second line as a tool to make the diverse city space merge and shrink. While planning the Leningrad subway, architects and engineers had to consider recent and historical developments. Bringing together urban developments from the nineteenth century up to the reconstruction in the 1940s was crucial for the construction of this urban infrastructure and the city space. The blue line, which opened in 1961, cuts through the city on a straight line. During the planning and construction process, city planners considered various routes and developments to bring together rather different parts of Leningrad and make the city grow into one urban space. Whereas the perception of city spaces is mostly connected to its surface, the subterranean structures play a crucial role to understand not just the development of the city space itself but also its current perception.