[
International Worm Meeting,
2005]
To understand the mechanisms of spatiotemporal cell positioning during embryogenesis, we are measuring and analyzing quantitative cell division patterns of wild-type and RNAi-treated embryos. Early development for 85 wild-type embryos and 604 RNAi-treated embryos (245 genes on the chromosome I and III) whose phenotypes were reported as 100% embryonic lethal (Fraser et al. 2000; Kamath et al. 2003) was recorded by 4D DIC microscope system with 66 focal planes at a distance of 0.5m between adjacent planes, at intervals of 40 seconds for 2 hours. The recorded images were processed by our cell lineage acquisition system (Onami et al. 2001), which detects nuclear regions in each image by image-processing, and then groups regions that correspond to the same nucleus at each time point and connects those groups that correspond to the same nucleus in adjacent time points by using tracking algorithm. Produced cell division pattern consists of 3D positions of nucleus at each time point and their connections from 1-cell stage up to 24-cell stage. To explore function of genes during early embryogenesis, we are developing bioinformatics methods for analyzing these quantitative cell division pattern data. To facilitate the analysis, we developed systematic method to quantify various features of cell division pattern, such as timing of cell division, direction of cell division, relative position between nuclei and cell movement. These quantified features were analyzed by using multivariate analysis methods, such as clustering and pair-wise correlations methods. We also developed methods for finding RNAi phenotypes on various quantified features and those for investigating properties of each quantified feature, such as normality of cell cycle duration. Quantitative analyses of cell division patterns using these methods are in progress.