#developmental genetics

[lolmythesis]

Put a worm where there's no food: it'll crawl away.

Developmental Genetics, Rockefeller University.

The long-range directional behavior of the nematode C. elegans.

[phil-iannaccone]

Dinosaurs, Fruit Flies, and Us

July 26th, 2013

There have been revolutionary advances in our knowledge of genetics in the past 30 years. This is particularly true in a field of endeavor called developmental genetics, which strives to understand how genes work to put us together. To make a baby that grows and eventually makes its own babies.

We have found that genes which coordinate development in the fruit fly are similar in structure, function, expression, and genomic organization to genes in human beings (i.e., how they are arranged on chromosomes, what regulates them and how they interact with each other). Yet fruit flies are not like us: among other obvious differences they have wings and we don't (even if we wish we did!).

The formation of wings or legs or a segmented abdomen or hundreds of other steps are all part of a genetically specified developmental program leading to a body plan, a process which is called pattern formation. The revolution in part is the understanding of the degree of conservation of the genes responsible across huge phylogenetic chasms. In other words the degree to which the genes are the same even though we evolved into different animals almost a hundred million years ago.

This knowledge implies that relatively few successful strategies for making a body plan made it through the Cretaceous-Tertiary Boundary (this was the time some 65 million years ago when a giant asteroid struck Earth and wiped out most life). It also implies that the variation between living things and newly evolving species came after that mass extinction event [Read more about the Cretaceous-Tertiary Boundary (or K-T Boundary as it's known) here, or listen to a BBC Radio 4 program about it here].

We are now in a position to know at a molecular level how multicellular organisms put themselves together and how mistakes in the process cause diseases like cancer and birth defects.

Developmental geneticists over the past few decades have researched fundamental and essential questions of life: How does fertilization occur?

What is compaction?

How can the relative location of cells in the embryo affect the genes they express?

Can the topology of the early embryo when it is only a few cells define a sequence of genetic events?

How are the genes that drive development organized in other animals like a fruit fly?

As we saw in a previous post (find it here), we can learn the answers to these questions and much more about humans from flies on a banana peel!

  A brief summary:

How limbs, organs, and every part of us grow and develop is part of an orchestrated and organized body plan through a process called pattern formation.

We can study simpler organisms like fruit flies to understand their pattern formation and how genes regulate the body plan.

Because of the mass extinction at the Cretaceous-Tertiary Boundary (or K-T Boundary), the species that survived and repopulated Earth still share some common genetic traits.

These shared traits allow us to apply what we've learned from simpler organisms to our own development.

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