P A Rorabaugh

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The possibility that Crassulacean acid metabolism (CAM) is subject to long day photoperiodic control in Portulacaria afra (L.) Jacq., a facultative CAM plant, was studied. Periodic measurements of (14)CO(2) uptake, stomatal resistance, and titratable acidity were made on plants exposed to long and short day photoperiods. Results indicates that waterstressed(More)
Although the Cholodny-Went model of auxin redistribution has been used to explain the transduction phase of gravitropism for over 60 years, problems are apparent, especially with dicot stems. An alternative to an auxin gradient is a physiological gradient in which lower tissues of a horizontal stem become more sensitive than upper tissues to auxin already(More)
Portulacaria afra (L.) Jacq., a perennial facultative Crassulacean acid metabolism (CAM) species, was studied under natural photoperiods and temperatures in San Diego, California. The plants were irrigated every fourth day throughout the study period. Measurements of (14)CO(2) uptake, stomatal resistance, and titratable acidity were made periodically from(More)
An alternative to the Cholodny-Went, auxin-transport hypothesis of gravitropic stem bending was proposed as early as 1958, suggesting that gravistimulation induces changes in sensitivity to auxin, accounting for differential growth and bending. To test the sensitivity hypothesis, we immersed marked, decapitated sunflower (Helianthus annuus L.) hypocotyl(More)
We have studied the effects of several porcine enteric polypeptide hormones on trout calcitonin (tCT) secretion in long-lived monolayer cultures of calcitonin-secreting (C-) cells derived from trout ultimobranchial glands. Gastrin, pancreozymin (CCK-PZ), glucagon, and secretin have dose-related stimulatory effects on tCT secretion; the distinct effects of(More)
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