Figure 4.

Essential TRGs have a biological role in chromosome segregation. (A) Wormnet connections for essential TRGs in C. elegans. Nodes which are TRGs are shown with a thick border; other genes have a thin border. Genes annotated with chromosome segregation GO terms which we found enriched in this set are colored in light blue, while other nodes are white. The Wormnet network shows the largest connected component of essential TRGs. (B) Yeastnet connections for essential TRGs in S. cerevisiae. The meaning of nodes and connections is the same as in (A). The Yeastnet network shows the largest connected component of essential TRGs as well as the top 100 connected genes. Essential TRGs are shown as enlarged nodes. (C) Targeting essential TRGs by RNAi results in chromosome-segregation defects in early embryos. Bacteria expressing dsRNA were fed to L4 animals that transgenically express fluorescent proteins marking chromatin (red) and the plasma membrane (green) for 72 hr, during which they developed into adults and laid embryos. Embryos were visualized by fluorescence microscopy. Nontargeting dsRNAs (control) had no effect on chromosome segregation, whereas targeting essential TRGs had penetrant chromosome-segregation defects leading to anucleate cells (blue arrowheads), multinucleate cells (yellow arrowheads), or chromatin bridges between dividing cells (white arrowheads). (D) Representative micrographs highlighting yeast cells with wild-type (top left panel) and aberrant spindle and spindle pole body morphologies (remaining panels). Dad2-GFP and Hta2-mCherry fluorescent signals are overlaid on DIC images, and cells of interest are indicated with white arrows (wild-type image) and blue arrows (mutants).