Live-cell imaging reveals square shape spindles and long mitosis duration in the silkworm holocentric cells

Proper chromosome segregation during mitosis requires both the assembly of a microtubule (MT)-based spindle and the assembly of DNA-centromere-based kinetochore structure. Kinetochore-to-MT attachment enables chromosome separation. Monocentric cells, such as found in human, have one unique kinetochore per chromosome. Holocentric cells, such as found in the silkworm, in contrast, have multiple kinetochore structures per chromosome. Interestingly, some human cancer chromosomes contain more than one kinetochore, a condition called di- and tricentric. Thus, comparing how wild-type mono- and holocentric cells perform mitosis may provide novel insights into cancer di- and tricentric cell mitosis. We present here live-cell imaging of human RPE1 and silkworm BmN4 cells, revealing striking differences in spindle architecture and dynamics, and highlighting differential kinesin function between mono- and holocentric cells.