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Researchers believe that the rocks containing these fossils, found in southern Anhui Provence, date between 635 million and 580 million years ago. The new types of organisms discovered in them include two that are fan-shaped, as long as 2 inches (5 centimeters), and resemble seaweed, as well as three other new types of organisms that are difficult to classify as animal or plant.
Until now, scientists had thought the oldest collection of fossils of large, complex life forms was the Avalon assemblage, dating back to about 579 million to 565 million years ago. It contained equally strange and unclassifiable organisms called rangeomorphs.
Baculoviruses infect invertebrates, with each species of virus typically infecting only one species of host. Caterpillars are a particularly favorite target; the insects swallow baculoviruses sprinkled on the leaves they munch. (“How did the viruses get there?” you may ask. Very good question–which we’ll get to in good time.)Once inside the caterpillar, a baculovirus infects a host cell. The cell produces huge numbers of new baculoviruses. They come in two forms. Some of the viruses can slip out of the host cell on their own to infect new cells. Others stay in the cell, which makes huge quantities of a viral protein called polyhedrin. The viruses become embedded in massive polyhedrin blocks, like fruits in a fruitcake. A caterpillar may produce 10 million viruses from swallowing a single viral fruitcake. It even becomes visibly swollen with all its new viruses.Soon the virus-packed host gets an uncontrollable urge to creep its way to the tops of plants, where it clamps on tight, hanging down as shown in the picture above. In fact, scientists noticed these strange death throes long before they knew that baculoviruses that caused it. They dubbed it tree-top disease.After an infected caterpillar takes its position at the top of a plant, the virus releases an enzyme that literally makes the animal dissolve. The tough viral fruitcakes come tumbling out, landing on leaves below where they can infect a new host.Hearing about tree-top disease gave me a deep sense of deja vu. A number of very different parasites have evolved the same strategy for getting to new hosts. Just a couple weeks ago, for example, I blogged about a fungus that sends its ant hosts to the undersides of leaves, whereupon the fungus sprouts branches out of the ant’s head and showers spores down on new victims. Lancet flukes send their hosts up to the tips of grass blades so that they can be eaten by grazing cows and sheep. It’s fascinating that even a virus–with just a few genes–can trigger this behavior as well.
...Vitargent combined the green fluorescent protein gene from jellyfish and spliced it into the genome of the fish directly next to a gene that detects oestrogen. Chemicals that have oestrogen-like activity cause the 1mm long fish larvae to express the modified gene, making them glow. The higher the concentration of oestrogen, the brighter the glow.