A screen to identify NETs that recruit chromosomes to the nuclear periphery. (a) An integrated lacO array marks chromosome 5 that tends to not be at the periphery in line 5.1. NETs fused to mRFP were exogenously expressed to screen for those involved in tethering chromatin to the NE. (b) Detection of the lacO array (arrowheads) and the transfected NETs (red) in the 5.1 line. The lacO array was not observed at the periphery in the untransfected cells (left) or the NET55 transfected cells, but was observed at the periphery in NET29 and NET39 transfected cells. Scale bar, 5 μm. (c) lacO array position was determined relative to five shells of equal area eroded from the periphery (1) to the centre (5) of the nucleus. To avoid errors in z from lacO arrays at the top or bottom of the nucleus, cells were only analyzed if the array occurred in the midplane where arrays occurring in the inner shells would be clearly internal. (d) Percentage of lacO-tagged loci in each of five erosion shells is plotted with the nuclear periphery (shell 1) to the left in dark blue and more internal localization occurring to the right and with lightening shades of blue. n = 50 cells for each NET. Single asterisks designate NETs with lower stringency P-values < 0.05 comparing the position of the array in the NET-transfected cells to the mRFP control using χ2 tests; double asterisks designate NETs with higher stringency P-values < 0.01. Statistics for all NETs are given in Additional file 1. UT, untransfected.