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5 December 2013 11:26 am ,
Vol. 342 ,
Dyslexia, a learning disability that hinders reading, hasn't been associated with deficits in vision, hearing, or...
Exotic, elusive, and dangerous, snakes have fascinated humankind for millennia. They can be hard to find, yet their...
Researchers have sequenced and analyzed the first two snake genomes, which represent two evolutionary extremes. The...
Snake venoms are remarkably complex mixtures that can stun or kill prey within minutes. But more and more researchers...
At age 30, Dutch biologist Freek Vonk has built up a respectable career as a snake scientist. But in his home country,...
Since arriving on the island of Guam in the 1940s, the brown tree snake ( Boiga irregularis ) has extirpated native...
An animal rights group known as the Nonhuman Rights Project filed lawsuits in three New York courts this week in an...
Researchers have been hot on the trail of the elusive Denisovans, a type of ancient human known only by their DNA and...
- 5 December 2013 11:26 am , Vol. 342 , #6163
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Blood Rh Factor's Job Described
30 October 2000 7:00 pm
Do you know your blood type? No matter what kind, it ends in either a "positive" or "negative," which refers to which kind of so-called Rhesus factor you carry. Although scientists have been typing blood for decades, no one knew the purpose of Rh proteins. Now a study shows that the proteins transport ammonium, a toxic by-product of energy metabolism, and possibly keep the blood's pH level balanced.
Until now, the Rh proteins that dot the surface of red blood cells were known for the problems they can cause for blood transfusions and pregnancy. If a patient receives a transfusion with mismatched Rh proteins, antibodies build up and attack the new blood. Likewise, an Rh-positive fetus can trigger an immune response in an Rh-negative mother that, if untreated, can injure or kill the fetus.
The link between Rh proteins and ammonium transport was unexpected. Several years ago, a team of yeast researchers led by Bruno André of the Free University in Brussels, Belgium, identified yeast proteins that transport ammonium. They entered the sequence of the gene that encoded the transporters in a genome data bank and saw that it closely matched the genes for Rh proteins in humans. To find out whether Rh proteins perform a similar function, the team knocked out ammonium transporter genes in yeast and replaced them with human Rh protein genes. The Rh proteins pumped ammonium out of the cells, they report in the November issue of Nature Genetics.
"This is the first strong evidence for a biological role" for Rh proteins, says hematologist Peter Agre of Johns Hopkins University. André and his team suggest that red blood cells pick up excess ammonium in the bloodstream and deliver it to the kidneys, which filter it out. This system would clear the blood of toxic ammonium and maintain pH, they claim.