Changes in Cotyledon mRNA during Ethylene Inhibition of Floral Induction in Pharbitis nil Strain Violet.

Floral induction in seedlings of Pharbitis nil strain Violet, with one cotyledon removed, was manipulated by applying various ethylene treatments to the remaining cotyledon during a 16 hour inductive dark period. Exposure of cotyledons to ethylene (100 microliters per liter) for 4 hours at different times during the dark period inhibited flowering to some extent, with inhibition being greater towards the end of the dark period. RNA from cotyledons given a 16 hour dark period (induced) or exposed to 100 microliters per liter ethylene throughout the dark period, which completely inhibited flowering, was examined. The poly(A)(+)RNA was translated in vitro using a wheat germ system, and the resulting translation products were analyzed by two-dimensional sodium dodecyl sulfate-polyacrylamide gel electrophoresis. There were substantial qualitative and quantitative differences between the poly(A)(+)RNA extracted from induced cotyledons and that from those exposed to ethylene throughout the dark period. Some of these changes are similar to those observed when flowering was inhibited by photoperiodic treatments (M Lay-Yee, RM Sachs, MS Reid 1987 Planta. In press). The significance of these findings to our understanding of the molecular control of flower induction is discussed.

Changes in cotyledon mRNA during floral induction of Pharbitis nil CV. Violet.

Floral induction in seedlings of Pharbitis nil Choisy cv. Violet, with one cotyledon removed, was manipulated by applying various photoperiodic treatments to the remaining cotyledon. Populations of polyadenylated RNA from treated cotyledons were examined to identify messages specifically involved in floral induction. The RNA was translated in vitro using a wheat-germ system, and the resulting translation products were analysed by two-dimensional polyacrylamide gel electrophoresis. Substantial qualitative and quantitative differences were found between mRNA from cotyledons of seedlings kept in continuous light (non-induced) and of seedlings given a 16-h dark period (induced). In contrast, inhibition of flowering with a night-break resulted only in one detectable, quantitative difference in mRNA.

An evaluation of spontaneous adverse drug reaction monitoring systems.

The Food and Drug Administration maintains an adverse drug reaction reporting system. Physicians report suspected adverse reactions that occur while a patient is taking a drug; reporting is voluntary and spontaneous. Data from spontaneous adverse drug reaction reporting systems are designed to signal that rare, unsuspected adverse reactions exist as a result of using a specific drug. Problems arise when attempts are made to use such data for other purposes. Specifically, spontaneous adverse drug reaction data, such as those published by the Food and Drug Administration, are inappropriate for calculating actual adverse drug reaction rates for specific drugs or for making safety comparisons among drugs. This is because these data are subject to numerous biases that can be easily identified and described but not easily corrected. As a result, data from spontaneous adverse drug reaction reporting systems bear little relationship to the actual incidence of adverse drug reactions.

Piroxicam in recent epidemiologic studies.

Data from nine epidemiologic studies indicate that nonsteroidal anti-inflammatory drugs as a class are much better tolerated by the gastrointestinal tract than is aspirin, and that piroxicam, specifically, is at least as well tolerated as other nonsteroidal anti-inflammatory drugs.

Psychophysical tuning curves for combination tones 2f1-f2 and f2-f1.

A simultaneous masking paradigm was employed to demonstrate that combination tones are "stimulus-like" in nature. Three musically sophisticated listeners adjusted the level of pure tones at various frequencies to just mask a pulsing signal corresponding to a tone at 1200 Hz and 20 dB SPL. The signal was produced by four stimulus conditions: (1) a pulsing tone at 1200 Hz; (2) a combination tone at 2f1-f2 = 1200 Hz produced by a continuous f1 at 1650 Hz and a pulsing f2 at 2100 Hz; (3) a control for condition 2 with a pulsing tone at 1200 Hz and a continuous f1 at 1650 Hz; and (4) a combination tone at f2-f1 = 1200 Hz produced by a continuous f1 at 1900 Hz and a pulsing f2 at 3100 Hz. Across subjects and stimulus conditions the shapes of the tuning curves were similar; whether for an externally presented single tone or a combination tone, minimum masker level (which corresponds to the tuning-curve "tip," the frequency at which masking is most effective) was always at frequencies near 1200 Hz. These findings are consistent with previous psychophysical as well as recent physiological evidence which indicates that, regardless of how generated, each of the combination tones 2f1-f2 and f2-f1 is present in the motion of the basilar membrane in the cochlear region around the characteristic place of the combination-tone frequency.

Photosynthesis as a function of short day induction and gibberellic Acid treatment in bougainvillea "san diego red".

Short day induction in Bougainvillea "San Diego Red" increases photosynthetic rates in mature leaves; gibberellic acid treatments, which inhibit flowering, cancel the short day effect. These results lend support of a nutritional hypothesis that suggests that in Bougainvillea assimilate supply to the reproductive axis increases before floral initiation and during flower development.

Flowering in bougainvillea: a function of assimilate supply and nutrient diversion.

Reproductive development, whether expressed as first node to flower or numbers of inflorescences developing, is promoted in direct relationship to leaf area and in inverse relationship to the numbers of axillary branches developing. Per cent soluble solids in the reproductive shoots vary with reproductive development. Cytokinin treatments promote inflorescence development and per cent soluble solids, further supporting a nutritional hypothesis in the control of flowering in Bougainvillea "San Diego Red." Gibberellin treatments inhibit reproductive development completely without significant lowering of per cent soluble solids, which is counter to expectations for a nutritional hypothesis. A closer examination of the reproductive axes, the tissues in which morphogenetic change occurs, must be made for the gibberellin-treated tissues.

Control of flowering in bougainvillea "san diego red.": metabolism of benzyladenine and the action of gibberellic Acid in relation to short day induction.

Benzyladenine (BA) and short day (SD) induction promote and gibberellic acid (GA) inhibits flowering in Bougainvillea "San Diego Red." GA is an overriding vegetative signal maintaining plants in a vegetative state even when BA is applied in SD conditions. SD promotes a more rapid conversion of BA to the ribotide and other "polar derivatives" (containing adenine derivatives). This effect of SD on BA metabolism is seen in root, stem, and apical bud tissues and is completely prevented by prior or simultaneous application of GA. GA treatment reduces the rate of polar derivative formation to that found in plants held in long days. The working hypothesis is that SD promotes flowering in Bougainvillea owing to reduced transport of gibberellins from leaves to roots and apical buds permitting metabolism of cytokinin, and perhaps other purine bases, to more polar forms that are more readily translocated and active in promoting reproductive development of the inflorescences axes.

Combination tones at frequencies greater than the primary tones.

The existence of audible combination tones at frequencies greater than the primary tones that generate them has long been problematic. With primary tones at frequencies f1 and f2, combination tones at f1 + f2 - f1, and other frequencies can be demonstrated and measured by using a contralateral probe tone to establish a binaural interaction with a given combination tone. The estimated amplitudes of these higher-frequency combination tones are generally 20 to 40 decibels below the amplitude of the primary tones.

Sound pressure in insert earphone couplers and real ears.

It is known that sound pressure, measured in couplers via a probe-tube microphone, often shows a pressure vs frequency response that drops sharply at a single frequency. In this study sound pressure was theoretically determined at various locations within a hard-walled cylindrical cavity, driven by a constant-volume velocity source with circular symmetry. At each location in the volume, a transfer impedance was defined as the ratio of pressure to inlet-volume velocity. In the region around the inlet, the transfer impedance passes through zero as it changes from negative to positive reactance with increasing frequency. Two hard-walled cavity examples were examined in detail (1) the main cavity of a 2-cm3 HA-2 coupler, and (2) a cavity having dimensions approximately equal to the occluded ear canal between an ear-mold tip and the eardrum. Contours of constant minimum sound pressure vs frequency are given for these two cylindrical volumes with experimental verification. Implications for probe microphone calibration and measurement of sound pressure in ears are discussed.

Nonmetabolic catalysis of C-furfuryl amino purine (kinetin) on plant surfaces, glass, and porcelain ware.

Kinetin-8-(14)C degraded rapidly upon drying on living or inert surfaces. However, when care was exercised to avoid taking solutions to dryness during fractionation of plant extracts containing (14)C-kinetin and before partitioning by thin layer chromatography, little degradation occurred. A procedure for 24-hour ethyl acetate partitioning, using a continuous liquid-liquid extractor, which permits nearly complete removal of kinetin from aqueous solutions, is herein described. High natural light intensities in the greenhouse or from fluorescent/incandescent sources greatly enhanced nonmetabolic degradation of kinetin on leaf (Bougainvillea) or glass surfaces, which indicated that this may be a confounding factor in analyzing metabolism of kinetin in plant tissues. One of the degradation products is probably adenine.

Enhanced inflorescence development in bougainvillea "san diego red" by removal of young leaves and cytokinin treatments.

Removal of young leaves and application of the cytokinin, N-benzyla-alpha-(tetrahydro-2H-pyran-2yl)-adenine promote inflorescence development in Bougainvillea "San Diego Red". Defoliation greatly increased the amount of assimilate accumulated at the shoot tip 1 to 2 days after treatment. Cytokinin applications further increased the amount accumulated and this increase was apparent 4 days before morphological changes could be detected at the inflorescence axes. Short days promoted inflorescence development and also increased assimilate accumulation at the reproductive axes; thus, it is suggested that the role of short day induction in bougainvillea may be that of redirecting the flow of assimilates, perhaps by its influence on cytokinin synthesis and distribution.