Who Killed T-Rex?

A QUANTUM OF SCIENCE

The King of the Dinosaurs may have been done in by a microscopic parasite

When paleontology researchers from major universities and museums around the world started to compare notes on the bone structures of particular specimens, they noticed something strange: cavities. In specific, Tyrannosaurus Rex cavities. Of the 61 specimens examined, 15% had significant lesions in the mandible (jaw bone), most of them occurring on both sides of the jaw. The earlier interpretation – that these were the result of intraspecies predation – was ruled out by comparison to the jaws of crocodiles, which form significant scar tissue when punctured by the teeth of other crocodiles. There was no sign of scarring, the cavities were simply eroded into the jaw bone, characteristic of a microbiological agent.

Researchers concluded that based on the similarities between the morphology and pattern of lesions in the T-rex specimens to those found in modern falcons, a protozoan known as Trichomonas gallinae was most likely responsible. The protozoan could have been transmitted either from infected prey or through violent contact between T-rex muzzles such as might be imagined in instance of either displays of dominance or outright cannibalism. Once the disease progressed to the stage found in many of the examined fossil specimens, feeding would become problematic or even impossible. In another modern equivalent, the Tasmanian Devil is actually starving itself into extinction following a face-biting behavior that spreads an oral cancer between individuals. While not conclusive in their theory that trichomonosis starved the T-rex to death, evidence is accumulating that it may have been the case for some populations of the dinosaur, and the potential exists that scientists may be able to extract DNA from these fossils and provide a more solid conclusion in the near future.

For more information:

Common Avian Infection Plagued the Tyrant Dinosaurs (Wolff et al)

Trichomonas gallinae (Wikipedia)

© AQOS / P. Smalley (2009)
Reproduction with attribution is appreciation

Curing the Mosquito

A QUANTUM OF SCIENCE

How can bacteria help protect humans from malaria?

Malaria is a deadly but neglected tropical disease that has received more money and attention in the last decade than in perhaps the preceding century. The disease is spread by mosquitoes in whose gut live one or more of five protozoan species of the Plasmodium genus. As a protozoa, it is neither a virus nor a bacteria but more like an amoeba or an algae, and thus it is more difficult to fight because its cells look more like human ones than either viruses or bacteria. Malaria is contracted by 350-500 million people every year, and approximately 1-3 million die of it annually - mostly sub-Saharan children. Now a scientist at the Johns Hopkins University Malaria Research Institute think he might have a unique way to help break the cycle of malarial infection.

The answer? Cure the mosquito.

For a long time it was thought that malaria could be controlled by using insecticides and bed screens to keep the mosquitoes away, but these approaches have both proven only partially effective. Insecticides also have their own toll on both human health and the environment, and rapidly become ineffective. But Dr. George Dimopoulos has found a species of bacteria living in the gut of the mosquito whose presence seems to inhibit the growth of the malaria protozoa. When he treated mosquitoes with an antibiotic, the bacteria died and the protozoa multiplied manyfold, making the mosquito a much deadlier vector for the disease. By helping this specific bacterium to stimulate the mosquito's immune system and cure it of the protozoans it carries, Dr. Dimopoulos believes, the spread of malaria could be controlled more effectively than with insecticides or bed screens alone.

If so, this could be a new and unprecedented breakthrough in fighting malaria, one of the great scourges of Africa.

For more information:
VOA News article

Public Library of Science article by Dr. Dimopoulos

Wikipedia entry on protozoa


© A Quantum of Science / Peter Smalley (2009)
Reproduction with attribution is appreciation