Example Research – Cell Lineage
Being transparent and amenable to laboratory manipulation, C. elegans
cell lineage was first completed by John Sulston in the 1980s. Cell lineage is similar to the family tree of cells. The development of a cell’s predecessor and successors can be determined from the lineage.
Creating the Cell Lineage of C. elegans
A bit of history:
“…[B]ut it sufficed to get us started in earnest on the cell lineage. The significance was that although Sydney had wanted from the beginning of the project to follow cell lineages, it was presumed that the most interesting development happened in the egg. So this was the only stage that had been studied, but it was proving very difficult to see anything. It meant, however, that there were already Nomarski DIC (differential interference contrast) microscopes in the lab.
Seeing my first cell division
Read more…. (PDF)
Drawing by Hand
The transparency of C. elegans made the lineaging possible. Dr. John Sulston spent one and a half years (in the dark) to complete the C. elegans cell lineage. Dr. Sulston hand-drew the real-time worm development. Originally, the C. elegans embryo development wasn’t recorded in video for lineaging.
“The cell lineage is the description of the history of each embryonic cell, beginning with the un-cleaved egg. The products of every division are traced until the rudiments of the embryonic organs become distinct.” (Ways of Knowing, John Moore, p. 494)
As the complete cell lineage (JPG, 1 MB) shows, from top to bottom, you can see an un-cleaved, just fertilized zygote, P0 cell divides into two daughter cells (AB and P1 cells) 
. The two daughter cells then divide into more daughter cells 
that eventually form a map and enable one to trace a cell’s predecessors and successors.
Microscopy Techniques
Later, Nomarski optics (also known as Differential Interference Contrast (DIC) microscopy) was also used:
(a one-cell embryo with paternal and maternal pro-nuclei meeting in the center)
This video shows the embryonic development from 1-cell to 100-cell:
(QuickTime, 18 MB)
Research Questions
- What is derived from each cell?
- Do cells from the same mother cell behave the same?
- Do cells migrate after they are born?
- Do all C. elegans embryos develop in the same pattern? Is this true for all organisms?
- Do neighbor cells affect the development of a cell?
More About C. elegans Cell Lineage
The C. elegans Cell Lineage Module: instructional materials for teaching cell lineage by inquiry. Resources can be used/adapted for teaching disciplines (e.g.: developmental biology, cell biology, genetics) with other instructional approaches (e.g.: lectures, lab) as well. Animations, movies, images and hands-on tools are included.
Credits
- Cell Lineage: The embryonic cell lineage of the nematode Caenorhabditis elegans, retrieved 12/10/04, from http://www.wormatlas.org/Sulstonemblin_1983/toc.html.
- Science as a way of knowing-developmental biology. (Moore, A. J., The American Society of Zoologists, 27, 415-573 (1987).
Random Worm Term
or nucleic acid or in the structure of an organ that reflects a common evolutionary origin. Molecules or sequences that exhibit homology are referred to as homologs. In contrast, analogy is a similarity in structure or function that does not reflect a common evolutionary origin.
