Figure 1.

Crystallization of HEX-1 from N. crassa in living insect cells. Light-microscopic images of Sf9 cells four days after infection with a recombinant baculovirus encoding the target protein (MOI = 1). Most cells produce a single crystal per cell (a). Two different crystal morphologies can appear. The first is a spindle-like morphology with flat ends and a slightly increased diameter in the middle (b) showing a hexagonal cross section (c). These crystals sometimes grow in a star-like manner, conjoined in the middle (d). The second morphology is bipyramidal (e) with pointed tips and a square base (f). These crystals can sometimes form somewhat irregular forms with rounded tips (g). Both morphologies can grow cytoplasmatically as well as within the cell nucleus [(b) versus (h) and (e) versus (i)]. After cell lysis the crystals show high stability in the cell-culture medium, while mostly sticking to cell remnants (j). Bipyramidal crystals constitute about 13% of the total crystal population. The size distribution shows that the bipyramidal crystals form shorter but broader crystals overall compared with the spindle-like crystals (k). Size bars: 50 µm (a), 10 µm (b)–(j).