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These stories describe NIGMS-funded medical research projects. Although only the lead scientists are named, they work together in teams to do this research.

Cancer Therapy's Got Rhythm

Day-night rhythms affect how well some cancer drugs work.

Day-night rhythms affect how well some cancer drugs work.

Scientists know that cancer therapy is more effective when given at certain times of the day. Research on the body’s daily cycle may explain why.

Circadian rhythms are physical, mental and behavioral changes that follow a roughly 24-hour cycle in synch with light and darkness in the environment. They are found in most living things, including animals, plants and even microbes.

They are to blame for jet lag and seasonal affective disorder. New evidence suggests that circadian rhythms also affect the safety and effectiveness of certain cancer drugs.

Molecular biologist Aziz Sancar of the University of North Carolina in Chapel Hill measured the activity at various times of day of a DNA repair system in the brains of mice. Some cancer drugs target these DNA repair processes.

Sancar discovered that the DNA repair system is most active in the afternoon and evening and least active in the morning. This may explain why cancer therapy is more effective early in the day because that is when this system is less able to repair DNA damage in cancer cells.
—Alison Davis

Why Sleep?

Nerve cell proteins (reddish orange) build up in the brains of sleep-deprived flies (right). Courtesy: UW Health Public Affairs

Nerve cell proteins (reddish orange) build up in the brains of sleep-deprived flies (right). Courtesy: UW Health Public Affairs

All animals sleep, including flies. Like us, these insects need more sleep if deprived of it, they perk up with caffeine and their primitive brains have small electrical surges while they snooze.

However, unlike people, flies breed quickly, and since researchers have a detailed knowledge of their genetics and behavior, flies are an ideal model system for studying biology.

Scientists are using fruit flies to find out why we sleep-and what happens when we do.

Neuroscientists Chiara Cirelli and Giulio Tononi of the University of Wisconsin-Madison conclude that sleep refreshes nerve cell connections that become overworked while we are awake.

They found that levels of proteins in synapses-the working ends of nerve cells-plummet at night in well-rested flies, presumably clearing away excess "noise" built up during the preceding day.

The scientists reason that the molecular housecleaning that takes place during sleep readies the brain for learning and allows it to save energy. If proven true in humans, the results could deepen understanding about insomnia and other sleep disorders.
-A.D.

Algae Clean Up Arsenic

This Yellowstone hot spring-fed creek is
green because the arsenic-eating algae have formed a thick mat. Courtesy: Tim McDermott

This Yellowstone hot spring-fed creek is green because the arsenic-eating algae have formed a thick mat. Courtesy: Tim McDermott

Arsenic is the most common toxic substance in our environment, and it is also a global health problem: Contamination of groundwater has led to poisoning deaths in many poverty-stricken areas of the developing world.

Geothermal environments, like the hot springs in Yellowstone National Park, are known for their high arsenic content and thus provide a natural lab for studying the metal.

Biochemist Barry Rosen of Florida International University in Miami and his team recently discovered algae living in Yellowstone hot springs that chemically change arsenic to make it less toxic. These unusual organisms thrive in extremely hot and acidic water-up to 135 degrees Fahrenheit, with a pH factor ranging from 0.5 to 3.5. In contrast, the pH range for drinking water is 6 to 8.5.

Rosen and his coworkers, ecophysiologist Tim McDermott 1 and chemist Chris Le 2 reason that the algae can survive in such harsh environments because they play an important ecological role in cycling arsenic.

Someday, the arsenic-tolerant algae may help with arsenic decontamination efforts around the world. —A.D.

Reading DNA Like a Book

A new genome-reading method scans
DNA like words in a book.

A new genome-reading method scans DNA like words in a book.

You know that DNA "letters" spell out instructions to RNA, which makes proteins. But how do slightly different DNA spellings of genes translate to the differences that makes each of us unique?

One way researchers are uncovering the meanings in our genes is by comparing human gene sequences to each other or to those of animals, which share a good amount of our DNA sequence.

Now, scientists have tweaked a computerized technique that scans the text in books to scan DNA instead. When all punctuation and spaces are removed from the text of a book, the sequence of alphabetic letters resembles the gene order of a genome.

Chemist Sung-Hou Kim of the University of California, Berkeley, used the method to create a dictionary of all adjacent DNA "words" in various genomes. He then counted how often the word features repeated.

When Kim tested his genome-scanning technique on actual online books, he discovered that the method was more successful at identifying related books than other text-scanning methods that searched for the frequency of real words. -A.D.

This page last reviewed on May 18, 2011