Ninety male Sprague-Dawley rats were exposed to 1:1-h light-dark (LD1:1) cycles for 50-90 days, and then they were released into constant darkness (DD). During LD1:1 cycles, behavioral rhythms were gradually disintegrated, and circadian rhythms of locomotor activity, drinking, and urine 6-sulfatoxymelatonin excretion were eventually abolished. After release into DD, 44 (49%) rats showed arrhyth...

For the scientific community, the ability to fly mice under weightless conditions in space offers several advantages over the use of rats. These advantages include the option of testing a range of transgenic animals, the ability to increase the number of animals that can be flown, and reduced demands on shuttle resources (food, water, animal mass) and crew time (for water refill). Mice have bee...

To identify genetic expression of mandibular condylar cartilage during natural growth and under mechanical strain as a result of mandibular advancement. One hundred and forty four 35 days old female Sprague-Dawley rats were sacrificed on 8 different experimental days. Total RNA was extracted for oligonucleotide microarray gene chips containing 15,923 transcripts. Sixteen genes representing the ...