Although the Human Genome Project announced the completed sequencing of 20,000 human genes more than 20 years ago, scientists are still working to grasp how fully formed beings emerge from basic genetic instructions.
Biomedical efforts to learn how disorders can take hold in the earliest stages of development would benefit from knowing specifically how complex organisms arise from a single fertilized cell. Researchers from the University of California San Diego have captured a new understanding of how embryonic development unfolds through the lens of a simple model organism.
This gallery depicts a collection of embryos after genes were blocked one at a time. The distinct outcomes (or characteristics observed) for each embryo reflects the specific functions of the genes tested.
The comprehensive report led by School of Biological Sciences scientist Rebecca Green and Professor Karen Oegema provides a play-by-play of how genes function during embryonic development in Caenorhabditis elegans (C. elegans), a millimeter-long roundworm known to biologists as “the worm.” Despite its tiny size, C. elegans has been a workhorse for scientists because so much of its biology, including early developmental stages, resembles that of higher organisms, including humans. The research, which forges a decade’s worth of work by a collaborative multidisciplinary team into a “genetic atlas,” is published in the journal Cell.
“By characterizing many of these poorly understood genes in a simple model organism, we can learn about what they are doing in more complex systems like humans,” said Green, a bioinformatics scientist and first author of the paper. “While the work is done using C. elegans, the majority of genes analyzed are present in humans and mutations in many of them are associated with human developmental disorders.”
The researchers developed an automated system for profiling the function of genes required for embryogenesis, the process by which a fertilized egg, which starts as a single cell, develops into an organism with different tissues, such as skin, digestive tract, neurons and muscles. They used time-lapse 4-D imaging to methodically track the function of each gene throughout all embryonic stages, including when cell identity is determined and when the tissues in the organism take shape. The researchers monitored this process using an approach known as “computer vision” to track specific aspects of development, including the number of cells in each tissue. They also tracked the mass, position and shape of the tissues within the developing organism.
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