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Science 20 May 1966:
Vol. 152. no. 3725, pp. 1078 - 1080
DOI: 10.1126/science.152.3725.1078
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Articles

Neurosecretory Cells: Daily Rhythmicity in Leiobunum longipes

Dona J. Fowler 1 and Clarence J. Goodnight 1

1 Department of Biology, Western Michigan University, Kalamazoo

A fluorometric-analysis procedure, used to quantitate indoles, confirmed the presence of 5-hydroxytryptamine (5-HT) in an arachnid; there was unimodal cyclic production of 5-HT in brain and intestinal tissues over a 24-hour period. The same tissues produced 5-HT after 80-day culture; bimodal cyclic output was indicated during continuous 24-hour study. One peak occurred at 0200 hours, at the same time as the peak in vivo, suggesting an endogenously controlled mechanism of secretion. The second peak occurred at midmorning, a time when production in vivo was lowest, suggesting that there is a possible feedback-control mechanism in the organism that inhibits the endogenous output of 5-HT.

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Science. ISSN 0036-8075 (print), 1095-9203 (online)