Where does the biological model in nature come from?

Zebra stripes, sea shells, butterfly wings: these are all examples of patterns in nature. Pattern formation is a puzzle for both mathematicians and biologists. How does the delicate texture of butterfly wings appear from a single fertilized egg? How does the pattern come from no pattern?

Using computer models and living cells, researchers at Johns Hopkins University have discovered a certain pattern that can guide cell movement and help us understand metastatic cancer cells. How to move.

According to Dr. Denise Montell, a biochemist at Hopkins University: 'Modeling is a classic issue of the embryology industry. At some point, the cells in the embryo must split into cells that grow into heart cells, liver, blood, etc. Although this has been studied for many years, there are still many things we don't understand. '

An example of pattern formation, the researchers looked at how six cells in the fruit fly separate themselves from neighboring cells and move from one position in the ovary to another in egg development process.'In order for this cell migration process to occur, you must have the cells to leave and the cells stay. There must be a clear distinction - the separation of cell types on the surface is identical. '

Previous work identified a specific signal needed for moving egg cells, the problem was that this signal was 'selected'. Like ink falling on wet paper, the signal moves between surrounding cells, gradually turning off when it moves outward . But the pattern requires clear boundaries - there is no gray area between the black and white stripes of a zebra, between liver and heart cells and, in this case, between migrating cells and cells in again.

(Photo: iStockphoto / Ismael Montero Verdu)

How are the selected signals converted into a clear or moving signal? By examining flies with variations in different genes, scientists found that a particular gene, called apontic , is important in converting selected signals.

According to Dr. Michelle Starz-Gaiano, postdoctoral fellow in biochemistry: 'When apontic genes are mutated, the difference between migratory and non-migrating cells is blurred. In those variations, we witness many cases where migrating cells do not accurately separate from neighboring cells but instead float as they move. ' This shows that only selective signals are not enough to launch an exact number of cells, but instead need help from apontic.

Once the team discovers the important apontic in making these cells move, they begin to imagine how apontic works. In collaboration with mathematician Dr. Hans Meinhardt, honorary lecturer at the Max Planck Institute in Germany, they designed a computer model that can reproduce how the selected signals are converted into commands for cells stay or move.

By making assumptions about each gene and distributing the function to each protein, the group built a simple circuit that could predict the action of a cell based on selective signals, apontic and one type. The previously discovered protein is slbo . Computer models show that in cells, selective signals activate both apontic and slbo . But apontic and slbo work against each other and fight each other: when one side gains the advantage, the other is weak, and thus helps the stronger side get stronger. This happens until a protein dominates a cell. If slbo wins, the cell moves and if apontic wins, the cell stays; so the clear separation between going and staying is formed.

"This is not only a new solution to the problem of how to create a pattern from no sample, but we also discovered that apontic is a new cellular migration agent," Montell said .

Cell migration may contain the spread of cancer cells from a root tumor to other parts of the body. Understanding and thereby being able to control the path of cell migration can prevent the development of new tumors.

"At this stage, it is more about understanding what are the positive and negative cell migration coordinators."

This work is funded by the American Cancer Society and the Health Research Institute.