THE SIMPLE TRUTH: ANIMAL DEVELOPMENT NOT
AS COMPLICATED AS IT SEEMS
Professor Ricardo Azevedo’s Research on the Simplicity of
Cell Lineages
Explained in Nature Magazine
HOUSTON, Jan. 13, 2005 – Shedding light upon evolution,
a University of Houston professor studying cell lineages now finds
surprising simplicity in the logic of animal development.
Ricardo Azevedo, an assistant professor in the department of biology
and biochemistry, specializes in how evolution changes the way animals
develop. His recent findings using computational biology to reveal
the surprisingly simple patterns of cell division in the embryos
of small invertebrates is described in a paper titled “The
Simplicity of Metazoan Cell Lineages,” appearing in the current
issue of Nature, the weekly scientific journal for biological and
physical sciences research.
“The significance of my findings is that these cell lineages
are not as complicated as many scientists have thus far believed,”
Azevedo said. “Our hope is that our approach of treating development
as a computer program will help developmental biologists to analyze
their favorite organisms.”
Since we now understand much about how genes evolve, the attention
of biologists like Azevedo has shifted toward elucidating the evolution
of developmental mechanisms in the hope of unraveling how evolution
modifies more complicated and, therefore, more interesting traits
like body size, aging or behavior.
Azevedo and his colleagues constructed an algorithm to contrast
the developmental complexity of different organisms based on their
sequences of cell divisions, known in the trade as cell lineages.
They compared the known cell lineages of three different nematode
worms and a sea squirt with those randomly generated by a computer
program. They found that the real embryos did not behave like the
computer-generated ones, but instead showed that these organisms
took fewer “different steps” to fully mature than predicted
by chance. In other words, the development of these animals is simpler
than it looks.
“It’s particularly noteworthy that all four organisms
showed the same pattern,” Azevedo said. “The sea squirt,
a chordate, has a general body plan similar – albeit simplified
– to that of humans, while the nematode worms are more distant
relatives of ours. Yet, they have all evolved toward a similar level
of developmental complexity.”
This type of consistency, says Azevedo, may not only impact developmental
biology, but also medicine. With humans being made up of trillions
of cells, cell lineage analysis has been slower to catch on when
compared to the study of the large groups of cells we call organs,
such as the liver and the brain. However, research into cancer and
stem cells has focused our interest on the behavior of individual
cells. The hope is that cell lineage analysis will become more important
in the future.
For a copy of the article, visit http://wwworm.biology.uh.edu/publications/azevedo05.pdf.
An evolutionary biologist who joined the UH faculty in 2003, Azevedo
received his undergraduate training at the University of Lisbon
in Portugal, followed by his doctorate from the University of Edinburgh
in Scotland. He conducted his postdoctoral research at Imperial
College in London and at the Albert Einstein College of Medicine
in New York.
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