TY  - GEN
T1  - Estimation of C. elegans cell- and tissue volumes
AU  - Froehlich, Jonathan J
AU  - Rajewsky, Nikolaus
AU  - Ewald, Collin Y
DO  - 10.17912/micropub.biology.000345
UR  - http://beta.micropublication.org/journals/biology/micropub-biology-000345/
AB  - How large are C. elegans’ tissues? To our surprise, we could not find any quantification of C. elegans’ tissue volumes. By reaching out to the community, we received the following suggestions on how to quantify tissue volumes: First, using tissue-specific fluorescent reporter transgenes, confocal microscopy, and automated segmentation. Second and third, using electron microscopy serial sections (Altun et al. 2020) or methylene blue/pararosaniline-stained cross-sections (McGee et al. 2011) and manual or semi-automated segmentation. Here, we decided to use an alternative approach by directly measuring cell and tissue volumes from the Virtual Worm model (Grove and Sternberg 2011, http://caltech.wormbase.org/virtualworm/). The Virtual Worm is a three-dimensional model of a young adult C. elegans containing cell shape and position based on various sources, including the WormAtlas (Altun et al. 2020), the “Mind of the Worm” (White et al. 1986), and the “C. elegans Atlas” book (Hall and Altun 2007). We determined tissue volumes in the free software Blender by measuring individual cell volumes using the plugin “3D print toolbox” and directly with the plugin “Mesh volume calculator” (see Methods) (Figure 1a). Our quantifications revealed that the intestine was the largest tissue, followed by the hypodermis, gonads (including the volume of the rachis containing the non-somatic germ cells), body wall muscles, cuticle, pharynx, and neurons (Figure 1b, Extended Data). The majority of the total model volume was contributed by the four tissues intestine, hypodermis, body wall muscle, and gonads (including the rachis and germ cells), and each of these roughly contributed by a quarter (Figure 1c, bottom). However, several non-cellular structures were not included in these measurements, for example, the pericellular pseudocoelom, additional spaces in the uterus, and especially the large extracellular cuticle that together could take up 1/6th or more of a total animal. The original Virtual Worm was based on resources that mostly relied on electron microscopy and dehydrating fixation protocols that reduce volume. This likely leads to a general underestimation of volumes. This is also indicated by a comparison between the total model volume of 1.4 million μm3 and the 2.2 million μm3 estimated for a live adult hermaphrodite (Grove 2012). Taken together, our calculations are a zeroth-order approximation of tissue size, however, we can infer relative tissue sizes. Thus, we conclude that intestine > hypodermis > gonads > body wall muscles > pharynx > neurons.
PY  - 2021
JO  - microPublication Biology
ER  -