A new way to study cell shape characteristics, or cell morphometrics, has been developed. This method, called lobe contribution elliptical Fourier analysis (LOCO-EFA), generates from digitalized 2D cell outlines meaningful descriptors that can be directly matched to morphological features. Cell morphometrics is increasing important in developmental biology, especially as advanced imaging technologies and analytical tools reveal more cell shape information.
The LOCO-EFA technique, described in a Development article published today, involves decomposing two-dimensional cell shapes—the shapes you can see under a microscope—into a series of ellipses. These are further broken down and regrouped in a specific manner to uniquely describe shape properties, which can be summed up to yield back the shape. The process resembles that of the geometric drawing toy Spirograph that uses circles to draw complex shapes.
Using mathematical procedures, these patterns are condensed into a series of numbers that add up to a characteristic "fingerprint." This captures the distribution of protrusions or lobes that comprise the complex geometry of the cell, leaf, or organ under scrutiny.
"Like the different notes played by instruments, our method is able to retrieve the pitch of a shape—for example its number of protrusions,” report Veronica Grieneisen of John Innes Centre. “Continuing the analogy, we can quantify amplitude—how pronounced the shape is. And, finally, we can distinguish timbre: in the same way one can distinguish between a violin and an oboe, our method can distinguish between different species or mutants and wild-types, even when displaying the same absolute number of main protrusions, the same pitch."
The tool will enable better phenotyping of cell shapes and also understanding of how cell shapes change in relation to others, and over time, she says. But the appeal and applications are much wider, "Our method will open the door to quantifying 2D shapes in all biology," Grieneisen says.