Blood found in 46-million-year-old mosquito Fossil

Culiseta species (USNM 559050) (Diptera: Culicidae), a blood-engorgedfemale from the Middle Eocene Kishenehn Formation of northwestern Montana.Note the distended and opaque dark-colored abdomen (compare to themale USNM 559051 in SI Text). From Hemoglobin-derived porphyrins preserved in a Middle Eocene blood-engorged mosquito by Dale E. Greenwalta,1, Yulia S. Gorevab, Sandra M. Siljestr?mb,c,d, Tim Roseb, and Ralph E. HarbacheImprobable event: The fossilised mosquito was found in a US lakebed

Mozzies have been annoying humans for centuries, but they've been sucking blood from other creatures for far longer, close to 50 million years, say scientists, who have ancient blood to prove it. Researchers have found components of red blood cells in a 46-million-year-old fossilised mosquito.

While the discovery sounds like the plot of the popular sci-fi novel Jurassic Park – where scientists use DNA extracted from an amber-encased mosquito to revive dinosaurs – the female specimen represents the world's first fossil of a blood-engorged mosquito.

As research has shown DNA cannot survive more than 6.8 million years, no genetic material was recovered. The insect, with its visibly extended abdomen, was found trapped in oil shale, a sedimentary rock from an ancient lakebed in north-western Montana.

Using non-destruction technologies, the team screened the fossil for a range of compounds, including two components of heme, the protein that transports oxygen in red blood cells.Researchers, led by Dale Greenwalt from the National Museum of Natural History, said the specimen was unique; its preservation an extremely improbable event. "The insect had to take a blood meal, be blown to the water's surface, and sink to the bottom of a pond or similar structure to be quickly embedded in fine anaerobic sediment, all without disruption of its fragile distended blood-filled abdomen," the researchers said in the Proceedings of the National Academy of Sciences.

The detection of these components, iron and porphyrin molecules, in the abdomen of the female – only females suck blood – confirmed the iron was from the insect's last meal and not part of the fossilisation process.

The female specimen was one of 36 mosquitoes recovered from the Kishenehn Formation, part of which formed around 46 million years ago during a time known as the middle eocene.

The fossils are unique because they were preserved in shale rather than amber, the material in which most fossil insects have been found, said the researchers.


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