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Metal light show follows fertilization
By Rachel Ehrenberg
Sex is often associated with metaphorical fireworks, but there’s a real shower
of sparks at the moment of conception.
Scientists have witnessed mammalian
eggs explosively releasing zinc atoms
just after fertilization in a series of brief,
intense outbursts that appear to jump-start embryonic development.
The research, reported online April
28 in ACS Chemical Biology , reveals new
details about how a single cell eventually becomes a full-blown organism
and highlights that metals such as zinc
can orchestrate major cellular events.
In living things, zinc is better known
for supporting roles, such as stabilizing
a protein’s conformation or assisting
enzymes that spur chemical reactions.
“This really shows that elements,
that chemistry, is in control of biology
in a way we haven’t thought about,” says
reproductive biologist Teresa Woodruff
of Northwestern University in Chicago.
May lessen severity of illness
rather than prevent infection
By Tina Hesman Saey
Sickle-cell hemoglobin may gas malaria
into submission, a new study proposes.
Carriers of a mutation that deforms
the oxygen-carrying protein in red blood
cells are well known to be protected from
malaria. Scientists used to think the
mutation prevented the malaria parasite
from entering blood cells. But researchers
led by Miguel Soares at the Gulbenkian
Institute of Science in Oeiras, Portugal,
now suggest another mechanism.
The sickle-cell mutation bumps up
production of a protein called heme
oxygenase- 1, which helps make carbon
monoxide gas. The gas can reduce inflam-
mation and protect against death in mice
with malaria infections in their brains,
the team reports in the April 29 Cell.
Using mice genetically engineered to
make human hemoglobin with the sickle-cell mutation, Soares and his colleagues
discovered that the mutation primes the
body to deal with the red blood cell–
shredding activities of the malaria parasite.
Hemoglobin breaks down more easily
in people with the sickle-cell mutation,
Soares says, releasing a toxic compound
called heme. To compensate, the body
makes more heme oxygenase- 1, leading
to more carbon monoxide production.
The carbon monoxide latches on to
hemoglobin and prevents heme from
popping off and causing more trouble.
The extra carbon monoxide also prepares cells for the effects of the malaria
parasite. The parasite can still infect
cells, but the host doesn’t get as sick,
allowing more time for the immune system to deal with the infection.
Mice infected with malaria fared well
when kept in a chamber with a tiny bit
of carbon monoxide, while infected mice
kept in a chamber with regular air died,
the team found. That finding suggests
that very low doses of carbon monoxide
could help treat malaria, Soares says.
Although the study carefully teases
apart the mechanism, researchers don’t
know how well heme oxygenase- 1 works
against malaria in people.
“Humans may not react as uniformly
as mice do,” says Michael Walther, formerly a senior immunologist at the
United Kingdom’s Medical Research
Council Unit, The Gambia.
This new mechanism may be one of
several ways sickle cell protects against
malaria, says Rick Fairhurst, an immunologist at the National Institutes of
Health in Rockville, Md. But he thinks
other immune system factors may be
more important for keeping malaria in
check in people with the mutation.