Questão 29

TEXTO

  Scientists are starting to understand why one
person’s face can look so different from another’s.
Working on mice, researchers have identified thousands
of small regions of DNA that influence the way facial
[5] features develop. The study also shows that tweaks to
genetic material can subtly alter face shape. The findings,
published in Science, could also help researchers to
learn how facial birth defects arise.
  The researchers said that although the work was
[10] carried out on animals, the human face was likely to
develop in the same way. Professor Axel Visel, from the
Joint Genome Institute at the Lawrence Berkeley
National Laboratory in California, told BBC News: “We’re
trying to find out how these instructions for building the
[15] human face are embedded in human DNA.”Somewhere
in there must be that blueprint that defines what our face
looks like.”
  The international team has found more than 4,000
“enhancers” in the mouse genome that appear to play a
[20] role in facial appearance. These short stretches of DNA
act like switches, turning genes on and off. And for 200
of these, the researchers have identified how and where
they work in developing mice. Prof Visel said: “In the
mouse embryos we can see where exactly, as the face
[25] develops, this switch turns on the gene that it controls.”
  The scientists also looked at what happened when
some of these genetic switches were removed from mice.
“These mice looked pretty normal, but it is really hard
for humans to see differences in the face of mice,”
[30] explained Prof. Visel. By comparing the transgenic mice
with unmodified mice, the researchers found that the
changes were very subtle. However some mice developed
longer or shorter skulls, while others have wider or
narrower faces. “What this really tells us is that this
[35] particular switch also plays a role in development of the
skull and can affect what exactly the skull looks like,”

he explained.
  Understanding this could also help to reveal why
and how things can go wrong as embryos develop in the
[40] womb, leading to facial birth defects. Prof Visel said:
“There are many kinds of craniofacial birth defects; cleft
of the lip and palate are the most common ones.And
they have severe implications for the kids that are
affected. They affect feeding, speech, breathing, they
[45] can require extensive surgery and they have psychological
implications.”While some of these are caused by genetic
mutations, the researchers want to understand how the
genetic switches interact.
  Professor Visel added that scientists were just at
[50] the beginning of understanding the processes that shape
the face, but their early results suggested it was an
extremely complex process. He said it was unlikely in
the near future that DNA could be used to predict
someone’s exact appearance, or that parents could alter
[55] genetic material to change the way a baby looks.

MORELLE,Rebecca,Science reporter,BBC World Service Disponível: .Acesso em: 8 dez. 2014. Adaptado.

According to the text, researchers are very hopeful that these findings