Blogs for March 15,16, 17,18,19

1. Which statement correctly identifies a difference bewteen the function of most arteries and veins?
a. Arteries carry red blood cells, whereas veins carry white blood cells.
b. Veins carry red blood cells, whereas arteries carry white blood cells.
c. Arteries carry blood to the heart, whereas veins carry blood away from the heart.
d. Veins carry blood to the heart whereas arteries carry blood away from the heart.

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Chickens ‘One-Up’ Humans in Ability to See Color

Researchers at Washington University School of Medicine in St. Louis have peered deep into the eye of the chicken and found a masterpiece of biological design.

Scientists mapped five types of light receptors in the chicken’s eye. They discovered the receptors were laid out in interwoven mosaics that maximized the chicken’s ability to see many colors in any given part of the retina, the light-sensing structure at the back of the eye.

“Based on this analysis, birds have clearly one-upped us in several ways in terms of color vision,” says Joseph C. Corbo, M.D., Ph.D., senior author and assistant professor of pathology and immunology and of genetics. “Color receptor organization in the chicken retina greatly exceeds that seen in most other retinas and certainly that in most mammalian retinas.”

Corbo plans follow-up studies of how this organization is established. He says such insights could eventually help scientists seeking to use stem cells and other new techniques to treat the nearly 200 genetic disorders that can cause various forms of blindness.

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Contaminated House Dust Linked to Parking Lots With Coal Tar Sealant

Coal-tar-based sealcoat — the black, shiny substance sprayed or painted on many parking lots, driveways, and playgrounds — has been linked to elevated concentrations of the contaminants polycyclic aromatic hydrocarbons (PAHs) in house dust. Apartments with adjacent parking lots treated with the coal-tar based sealcoat contained house dust with much higher concentrations of PAHs than apartments next to other types of parking lots, according to new research published online in Environmental Science and Technology (ES&T).

The study was conducted in Austin, Texas, by scientists at the U.S. Geological Survey (USGS).

Coal tar is a byproduct of the coking of coal, and can contain 50 percent or more PAHs by weight. Coal-tar-based pavement sealants therefore have very high levels of PAHs compared to other PAH sources (e.g., soot, vehicle emissions, used motor oil). PAHs are an environmental health issue because several are probable human carcinogens and they are toxic to fish and other aquatic life.

Small particles of sealcoat, which contains extremely high concentrations of PAHs, likely are tracked indoors by residents after they walk across the parking lot. The study found that apartments adjacent to coal-tar-sealcoated parking lots contained concentrations of PAHs in house dust with that were 25 times higher than in house dust from apartments with concrete, asphalt, Read the story »