Replication of action of cholecystokinin tetrapeptide in panic disorder: clinical and behavioral findings.

Eleven patients with panic disorder were challenged with cholecystokinin tetrapeptide (CCK-4) on two occasions. The effects of CCK-4 were consistent except symptom onset was more rapid with the second injection. Demonstrating that the effects of CCK-4 are reproducible in panic patients opens the doors for studies of the effects of drug treatment on CCK-4-induced panic.

Photoreactions Controlling Flowering of Chrysanthemum morifolium (Ramat. and Hemfl.) Illuminated with Fluorescent Lamps.

Flowering of chrysanthemum plants under short photoperiods, as is well known, is prevented when the plants are illuminated near the middle of the long night. Such illumination inhibits flowering whether it is given continuously or intermittently, and whether it comes from incandescent or from fluorescent lamps. We discovered, however, that fluorescent light applied intermittently (cyclically) throughout the entire 16-hour long night was far less inhibitory than when applied during only part of this dark period. By contrast, incandescent filament illumination is strongly inhibitory under these conditions. The cycles of fluorescent light usually lasted 15 minutes, 1.5 minutes of light followed by 13.5 minutes of dark. When such cycles were applied for only 12 hours, leaving 4 hours of uninterrupted darkness in each long night, inhibition of flowering was complete again.

Leaflet movement of Mimosa pudica L. Indicative of phytochrome action.

1. Closing movements of Mimosa pudica pinnae, upon change from light to darkness, depend upon the presence of phytochrome in the far-red-absorbing form. 2. The potentiated control of closing movements by phytochrome can be repeatedly established and reversed by repeated alternations of red and far-red radiation, respectively. 3. Action spectra were measured for the potentiation of closure and for its reversal. 4. The response to phytochrome action is evident in 5 minutes and is fully expressed in 30 minutes. 5. This rapid response and the more rapid potentiation with half times of less than 1 minute for several other responses to phytochrome action indicate that the primary action of phytochrome ist not gene activation, but rather metabolic control at the substrate level.

Opposing Actions of Light in Seed Germination of Poa pratensis and Amaranthus arenicola.

Action spectra were measured for suppression of germination of Poa pratensis L. and Amaranthus arenicola I. M. Johnston seed under prolonged or continuous irradiation. The action maxima for both types of seeds are near 720 nm. The maxima are unchanged in position or magnitude in the presence of radiation in the region of 600 to 670 nm adequate to maintain phytochrome predominantly in the far-red-absorbing form. A reversible potentiation of germination to change in form of phytochrome was observed for both seeds. The bearing of these findings on a high-energy regulatory light response is discussed.

Photocontrol of Mimosa pudica L. leaf movement.

1. Mimosa pudica L. pinnae close in darkness when phytochrome is predominantly in the far-red-absorbing form (Pfr) and remain open when Pfr is low [6]. The leaflets remain open, however, in normal light periods irrespective of the form of phytochrome. Pinnae, after closing in darkness, regularly reopen in light. 2. An action spectrum for the opening response shows maxima for effectiveness near 710 and 480 nm. This action spectrum is similar to that for a high-energy response affecting morphogenesis in many plants. 3. Dropping of the petiole of M. pudica can be photostimulated by irradiation of the primary pulvinus after holding the plants in darkness [4]. 4. The photostimulation of the primary pulvinus is effective only at wavelengths less than 520 nm. Wave bands in the region of 400 to 470 nm are about equally effective. 5. These photoresponses of M. pudica are related to current discussion about the nature of the high-energy and phytochrome photomorphogenic reactions.

The high-energy light action controlling plant responses and development.

Evidence is advanced for a network of three photoreactions and five dark reactions in control of plant growth and development by phytochrome.