Cancer Viruses

Cancer Viruses

Worldwide, cancer viruses are estimated to cause 15 to 20 percent of all cancers in humans. Most viral infections however, do not lead to tumor formation as several factors influence the progression from viral infection to cancer development. The hepatitis B virus (shown above) is an example of a cancer causing virus that has been linked to liver cancer in people with chronic infections.

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Dinosaur Feather Color Determined

Friday March 9, 2012

This is a reconstruction of a Microraptor based on digital overlays of nine fossilized specimens. Credit: AMNH/M. Ellison

Researchers have determined the feather pattern and color of an ancient four-winged dinosaur known as Microraptor. After analyzing a Microraptor fossil discovered in China, it was determined that the creature's feathers were iridescent with hues of black an blue. Comparable in size to a pigeon and in color to a crow, this winged dinosaur had anatomical features similar to a bird, but was not a bird. Microraptor was a non-avian dinosaur, in the same group of dinosaurs as Velociraptors.
According to one of the authors of the study Mark Norell, "This study gives us an unprecedented glimpse at what this animal looked like when it was alive. There's been a lot of speculation about how the feathers of Microraptor were oriented and whether they formed airfoils for flight or whether they had to do with sexual display. So while we've nailed down what color this animal was, even more importantly, we've determined that Microraptor, like many modern birds, most likely used its ornate feathering to give visual social signals." The researchers also believe that Microraptor's tail was used for courtship displays as opposed to helping the bird during flight.
Learn more about this study, see:

• Feathered Dinosaur Offers Fresh Evidence That Feathers Evolved to Attract Mates (Science Daily)

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Angiosperms

Thursday March 8, 2012

Photo courtesy PDPhoto.org

Angiosperms, also called flowering plants, are the most numerous of all the divisions in the Plant Kingdom. They are vital to all life on earth as they provide oxygen, shelter, clothing, food, and medicine for other living organisms. With the exception of extreme habitats, angiosperms populate every land biome and aquatic community.
Angiosperms are characterized by two basic systems: a root system and a shoot system. The flower, a component of the shoot system, is responsible for seed development and reproduction. Flowers that contain both male and female reproductive structures (stamens and carpels) are called perfect flowers. Flowers that are missing either stamens or carpels are called imperfect flowers. A complete flower contains not only stamens and carpels, but sepals and petals as well.