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The Blood-brain Barrier

In the human brain, there are approximately 400-425 miles of capillaries. Because the brain is basically a small neurochemistry factory, which makes our behavior a function of its interior chemical balances, the brain must protect its own chemical integrity by carefully controlling the levels of chemical substances in the brain's blood supply. That ...

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BloodBrain
Biology

Marmaduke and the Taco Bell Chihuahua Are Cousins

You would never think Marmaduke, the enormous great dane of the newspaper cartoons, and the tiny Taco Bell chihuahua are close relatives. But the fact is, ALL dogs are pretty close relatives. ... Continue reading

Marmaduke
Biology

Is It Sexism or Racism?

Can you judge a cat by the color of its coat? Well, you can judge the gender by the color of its coat! Only 1 in 27 orange cats are girls, and more surprisingly, only 1 in 3000 calico cats are males! ... Continue reading

SexismRacism
Chemistry

What Are Aerosols?

Aerosols are tiny particles suspended in the air. Most occur naturally, originating from volcanoes, dust storms, forest and grassland fires, living vegetation, and sea spray (Figure 1). Human ... Continue reading

Aerosols
Biology

Embryo Transfer and Cloning

Scientists use embryo transfer technology to obtain more offspring from a genetically superior animal. For instance, if a farmer owns a cow that produces excellent milk and wants more cows to produce ... Continue reading

EmbryoTransferandCloning

Resistance is NOT Futile!

ResistanceisNOTFutileMaybe if you are a Star Trek heroine up against the Borg, 'resistance is futile.' But if you are a germ that makes people sick, resistance - to antibiotics - is not futile at all.

When penicillin began to be widely used over fifty years ago, it could kill most of the bacteria that made us sick. Such bacteria are called 'pathogens,' to distinguish them from the many bacteria that are harmless or even useful. Nowadays, many pathogens are 'resistant' to a lot of the antibiotics we use to combat them. They have evolved the ability to fight off the effects of the drugs, so the drugs cannot cure you. This can be very dangerous in hospitals, where drug-resistant pathogens can spread rapidly and kill many people.

How can bacteria evolve drug resistance so quickly? The genes for drug resistance are usually not carried as part of the regular chromosome, but on extra rings of DNA called plasmids. These can be passed on to the bacterial cell's descendants, and can also sometimes be passed around to any other bacteria that happen to be in the area, even those of other species. If a drug kills all the susceptible bacteria, any few that are resistant will be free to multiply without competition and take over the population. So we are involved in an 'arms race' between biologists and chemists inventing new antibiotics, and pathogens inventing new ways to resist them.