MPhil Thesis Presentation - Allometric Analysis of the Growth in Worm Body and Cellular Constituents Regulated by BMP/DBL-1 Pathway in Specific Cell Types in Caenorhabditis elegans

To understand the coordination of volume and dimension control among bodies, cells, nuclei and ploidy, we use C. elegans as a multicellular organism to address questions about size regulation. Correlation analysis was conducted on the relationships among worm body size, cell size, nucleus size and ploidy of intestinal cells, specifically Int2 cell. The study also investigates the change in sizes of worm body and cellular constituents of multiple cell types via BMP signaling. By addressing the question, we want to find out how the size of a multicellular body be constituted from the sizes of its cellular constituents.

For all the volume and dimensions measured, it is found that in C. elegans, body volume and dimensions are positively correlated with those of Int2 cells, and such correlation is the strongest comparing with the size correlations among worm bodies, Int2 nuclei and ploidy. The result also shows that the changes in length and width are independent of each other for worm bodies and Int2 cells. Furthermore, BMP signaling has differential effect on the sizes of multiple cell types. The volumetric changes of Int2 cells and their nuclei fluctuates the most, when BMP level changes, over those of oocytes and coelomocytes.

This study concludes that body volume and dimensions control act through the change in the volume and dimensions of Int2 cell, rather than those of Int2 nucleus and Int2 ploidy. The growth of Int2 cells is consistent with the worm body longitudinally but not radially. Moreover, comparing with oocytes and coelomocytes, Int2 cells have more contribution to the BMP-dependent volume change of worm body.