That Orange Goo? Rust Fungus

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The additional examination results of the orange goo from Alaska's remote Kivalina village are in — and they show that the suspected eggs are not eggs at all, but rather the spores from an unidentified species of rust fungus, a common plant disease.

BLOG: Mystery Orange Goo Invades Alaska Village

When NOAA marine biologists in Juneau first viewed the substance under regular microscopic magnification, they saw tiny orange beads what they estimated to be about 100-200 microns in diameter, a range typical for marine invertebrate eggs.

Still, to conduct further testing they sent a sample to the Marine Biotoxins Lab at the NOAA National Ocean Service Center for Coastal Environmental Health and Biomolecular Research, based in Charleston, S.C.

Suspicions were soon raised over whether or not these were indeed microscopic eggs.

Invertebrate marine biologist Jason Hodin at Stanford, upon seeing the regular microscope image and asked if these might be sea urchin eggs as one Discovery News reader suggested, told Discovery News: "They don't look like urchin eggs to me, more like mollusk eggs…if they are in fact eggs at all."

He pointed out that the mystery orange substance under regular magnification did not seem to show any cleavage to indicate cellular division. If these were eggs he asked, "why are they all apparently unfertilized? In a mass spawning event, one expects males to spawn too."

Toxicologist John Ramsdell, branch chief scientist of the marine biotoxin lab in Charleston, told Discovery News that his team was conducting X-ray diffraction analysis, to identify what element in the periodic table this material was composed of, as well as electron microscopy imaging which provides a magnified view of the material that is 2,500 times what the human eye can see.

Taxonomist Steve Morton with the NOAA Charleston lab explained the diffraction analysis further. He told Discovery News that: "The EDS [Energy-dispersive X-ray spectroscopy] told us that the cell wall was organic and not made of minerals. Many small protozoans have cell wall composed of different minerals. This was one pieces of evidence we used to narrow the possibilities."

The image at right shows the spines on the spores in detail as seen under electron microscopy. This technique also provided the image at the top of this blog that showed the substance was much smaller than first identified: slightly more than 10 microns in diameter. That took these mystery eggs and knocked them down into the spore range for sizes. The marine physiologists working with a network of specialists then identified the spores as belonging to the Pucciniales order of fungi, a plant parasite.

"The spores are unlike others we and our network of specialists have examined; however, many rust fungi of the Arctic tundra have yet to be identified," reported Morton in a press release.

"Rust fungi reproduce to infect other plants by releasing spores which disperse often times great distances by wind and water. However, whether this spore belongs to one of the 7,800 known species of rust fungi has not yet been determined," announced the marine physiologists in the press release.

IMAGE 1: Electron microscopy image of the orange substance, now identified as spores from a rust fungus in Kivalina, Alaska. (NOAA)

IMAGE 2: Regular microscopic magnification of the orange substance from Kivalina, Alaska. (NOAA)

IMAGE 3: Detailed electron microscopy image of the orange substance from Kivalina, Alaska. (NOAA)

IMAGE 4: A soya rust (Phakopsora pachyrhizi) on diseased Soybean leaves. (Corbis)

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