Do we even understand the key principles let alone the specific details that orchestrate development biology? We believe that the answer to this question is still no.
……..we believe imaging will play a key role in advancing our understanding of developmental mechanisms across the scales….. imaging can be used to watch, measure, and even perturb developmental processes at all the relevant scales: molecular, cellular, tissue, and organismal. Importantly, we wish to challenge the simplistic notion that imaging is inherently ‘descriptive’ while molecular approaches are inherently ‘mechanistic’…………..key mechanisms and principles are found at many scales. Imaging can assay all of these scales, while molecular approaches are often irrelevant. Observing that tissue Y does not form when gene X is missing does not constitute an explanation of how tissue Y forms, nor what key principles are important in controlling its formation; it is important information, but it is an observation that should begin a mechanistic investigation, not end one. On the other hand, careful time-lapse microscopy has the potential to reveal the dynamics of gene regulatory networks, collective behaviors of cells, and tissue mechanics that underlie the formation of tissue Y.
The molecular paradigm of development has several limitations. One is that mechanism can often not be reduced to a single gene. As developmental biologists, we know that you cannot really draw a straight line between genes and phenotypes. Rather, the mechanisms that control development happen through the often nonlinear interactions of many genes in a dynamic network. Another limitation is that currently, much of development uses only a static readout such as looking at the terminal phenotype of a mutant. Understanding function often results from seeing the dynamics of a process occurring over time such as protein levels in a molecular circuit going up and down as a cell fate decision is computed.
The final limitation of the current paradigm is that mechanism does not occur only at the molecular level; mechanism happens at all scales…………….
Microscopy to mechanism across the scales of development, Harvard and Oxford Universities