After leaving this trail of cellular death and destruction in its wake, the parasite is finally taken up again from the blood when another mosquito bites. Then it reproduces and waits for the mosquito to bite again to infect another person.
Researchers have long assumed that the form of the parasite that infects red blood cells, called a merozoite, was released from a ruptured liver cell and moved on its own back to the bloodstream. But studies in the laboratory have shown that the liver's resident macrophage immune cells happily gobble up free-moving merozoites.
"This was a paradox," said Ménard. "We could not understand how the rate of infection could be so successful."
Heussler's research team noticed irregular protrusions on the surface of liver cells that had been grown in a culture dish and infected with malaria. So they asked Ménard and Amino for help finding out whether liver cells in an infected animal developed the same protrusions.
Amino captured a series of images inside living mice at one-second intervals to track the parasites' journey. By using parasites labeled with a green fluorescent marker and staining the mouse's blood vessels with a red fluorescent marker, Amino was able to record microscopic images inside the animal's liver. He found that not only did the structures Heussler's group saw on the liver cells in the culture dish, called merosomes, protrude from the animal's liver cells as well, but the scientists watched as they pinched off and carried the parasite safely into the blood vessels.
Amino recalls watching the first data "movie" with Heussler. They could clearly see the merosome forming, pinching off the parasite, and traveling away with it along the blood vessel. "That is the beaut
'"/>
Source:Howard Hughes Medical Institute