Experimental separation of sensory and motor functions in pea tendrils.

When illuminated pea tendrils from light-grown plants are rubbed on their abaxial side, they rapidly coil in a spiral fashion. If similar tendrils are held in the dark for 3 days and then rubbed, however, they will not coil until they are subsequently illuminated. They can remain uncoiled in the dark for as long as 2 hours after stimulation, and will still coil immediately when they are illuminated. Tendrils that are rubbed and held at 25 degrees C will coil, but those treated at 5 degrees or 10 degrees C will not. However, tendrils rubbed at 25 degrees C and kept from coiling for an hour at 5 degrees C, will immediately coil when restored to the higher temperature. These observations are interpreted to imply separation of sensory and motor functions.

Phytochrome-mediated bioelectric potentials in mung bean seedlings.

Excised root tips from dark-grown mung bean seedlings (Phaseolus aureus) that adhere to a negatively charged glass surface when irradiated with red light and release when irradiated by far-red light develop a positive bioelectric potential (about 1.0 millivolt) at the tip in red light and a negative bioelectric potential in far-red light. The sign of the bioelectric potential was repeatedly photo-reversible, and the adhesion and release kinetics were similar to those of the development of the bioelectric potentials. Photoconversion of the phytochrome holochrome perhaps changes permeability characteristics of the cell membrane, resulting in an induced localized electrochemical gradient manifested as a bioelectric potential. This supports the view that phytochrome in situ is membrane bound.

A pea mutant for the study of hydrotropism in roots.

Plant roots grow in the direction of increasing soil moisture, but studies of hydrotropism have always been difficult to interpret because of the effect of gravity. In this study it was found that roots of the mutant pea ;Ageotropum' are neither gravitropic nor phototropic, but do respond tropically to a moisture gradient, making them an ideal subject for the study of hydrotropism. When the root caps were removed, elongation was not affected but hydrotropism was blocked, suggesting that the site of sensory perception resides in the root cap.

Cholinesterases from plant tissues. VI. Preliminary characterization of enzymes from Solanum melongena L. and Zea mays L.

Enzymes capable of hydrolyzing esters of thiocholine have been assayed in extracts of Solanum melongena L. (eggplant) and Zea Mays L. (corn). The enzymes from both species are inhibited by the anti-cholinesterases neostigmine, physostigmine, and 284c51 and by AMO-1618, a plant growth retardant and they both have pH optima near pH 8.0. The enzyme from eggplant is maximally active at a substrate concentration of 0.15 mM acetylthiocholine and is inhibited at higher substrate concentrations. On the basis of this last property, the magnitude of inhibition by the various inhibitors, and the substrate specificity, we conclude that the enzyme from eggplant, but not that from corn, is a cholinesterase.

Neurologic findings in men with isolated hypogonadotropic hypogonadism.

We studied the neurologic abnormalities in 41 men with isolated hypogonadotropic hypogonadism. Findings included anosmia, hyposmia, mirror movements, ocular motor abnormalities, cerebellar dysfunction, and pes cavus foot deformity. One-third of the subjects had a family history of delayed sexual maturation. Patients with a family history of delayed sexual maturation had a significantly higher incidence of olfactory dysfunction, mirror movements, and pes cavus foot deformity. Our data suggest that isolated hypogonadotropic hypogonadism and its accompanying neurologic abnormalities may arise from a genetically linked developmental abnormality of CNS structures.

Temporary loss of foveal contrast sensitivity associated with panretinal photocoagulation.

Snellen visual acuity and spatial contrast sensitivity measurements were used to monitor changes in foveal vision in two patients undergoing argon laser panretinal photocoagulation (PRP) in both eyes for proliferative diabetic retinopathy. Foveal edema developed in one of the four eyes. The remaining three eyes showed no signs of foveal edema, but developed temporary losses in high spatial frequency contrast sensitivity during the closely spaced PRP treatments. Since Snellen visual acuity remained stable at the prelaser level, these results indicate the need for more sensitive measures of visual resolution to monitor foveal integrity in patients undergoing PRP.

Spatial contrast sensitivity. Importance of controlling the patient's visibility criterion.

Clinical spatial contrast sensitivity measurements are typically made using psychophysical methods that do not specify the response criterion being used by the patient in judging grating visibility. Results of this report show the necessity of such methods for (1) maximizing detectability of early contrast sensitivity deficits by minimizing normal sample variance, and (2) ensuring that changes in an individual's contrast sensitivity reflect changes in vision and not simply fluctuations in the patient's criterion for judging grating visibility.

Abnormal retinal function associated with fenretinide, a synthetic retinoid.

Five patients with basal cell carcinoma received fenretinide. Two patients while receiving the drug had evidence of abnormal rod photoreceptor function that reversed rapidly on cessation of therapy. We speculate that fenretinide may interfere with the binding of vitamin A to opsin or with the transport of vitamin A.

Imaging of urinary tract disease. Current approaches.

Current modalities and techniques used in imaging of the urinary tract offer prompt and accurate diagnoses as well as treatment in some cases. Careful planning and judgement in the choice of the imaging sequence is important in avoiding redundant or ill-advised tests. Individual tailoring will be necessary in some patients. It is hoped that with the rational use of the diagnostic tools now available and with the continued improvement in MRI technology, safe and accurate diagnoses will be expected in practically all patients with diseases of the urinary tract.

The effect of metoclopramide on the Ganzfeld electroretinogram.

Antecedent light flashes enhance the amplitude of the electroretinogram (ERG) oscillatory potentials, but do not modify other ERG responses nor dark-adaptation sensory thresholds. Metoclopramide infusion (i.v.) has a generally attenuating effect on the ERG, which is more evident under conditions of dark- than light-adaptation. Metoclopramide decreases the peak amplitude of the rod b-wave and the dark-adapted cone b-wave in a similar manner; it also significantly increases the implicit time of the rod b-wave, but not of the dark-adapted cone b-wave. In addition metoclopramide reverses the enhancement of the oscillatory potentials by the antecedent light flashes.

Microscopic artifact found during examination of the skin: plant hair of Viburnum dentatum.

Examination of skin specimens with microscopic techniques requires differentiation of pathogenic structures from artifact. While preparing potassium hydroxide preparations for fungal identification or immersion oil preparations for scabies identification, we have recently seen several examples of a bizarre stellate or cruciform plant structure. These artifactual particles were identified as plant hairs from Viburnum dentatum, or arrowwood. Clinicians and laboratory technicians should be aware of this artifact in order to interpret microscopic skin specimens appropriately.

Evidence for the regulation of phytochrome-mediated processes in bean roots by the neurohumor, acetylcholine.

Using pharmacological and chromatographic techniques, it was shown that acetylcholine was present in all organs of both light- and dark-grown mung bean seedings (Phaseolus aureus). The highest concentrations were found in tissues containing active growing points: buds and secondary roots. Within 4 minutes, red light caused an increase in the efflux of acetylcholine from secondary root tips as well as a significant increase in the endogenous titer. Four minutes of subsequent far red light reduced the latter to a level comparable to that in the dark.Acetylcholine, given for 4 minutes in the dark, was able to substitute for red light in reducing the formation of secondary roots, inducing increased H(+) efflux, and causing the root tips to adhere to a negatively charged glass surface. Acetylcholine-esterase and atropine inhibited the latter phenomenon, whereas eserine inhibited the far red-induced release from glass. THESE AND OTHER DATA SUPPORT THE CONCLUSION THAT ACETYLCHOLINE FUNCTIONS IN MUNG BEAN ROOTS AS IT DOES IN ANIMAL SYSTEMS: by mediating changes in ion flux across cell membranes. It also seems probable that acetylcholine acts as a local hormone which regulates these phytochrome-mediated phenomena.

The Role of ATP in Mechanically Stimulated Rapid Closure of the Venus's Flytrap.

When the midribs of untreated traps of Dionaea muscipula are frozen in liquid nitrogen after rapid closure, they contain significantly less ATP than those frozen before closure. Exogenous ATP causes a significant increase in the rate of mechanically stimulated trap closure. Illuminated traps close faster than those kept in the dark. The traps of plants placed in 100% O(2) close much faster than do air controls, while 100% CO(2) inhibits closure. It is concluded that ATP is probably the native source of potential energy for contraction of the trap's midrib, and that if the endogenous ATP titer is increased by oxidative phosphorylation or an exogenous source, the trap will close faster.

Thigmomorphogenesis: The response of plant growth and development to mechanical stimulation : With special reference to Bryonia dioica.

When young plants of Hordeum vulgare. Bryonia dioica. Cucumis sativus. Phaseolus vulgaris. Mimosa pudica. and Ricinus communis. were given a gentle mechanical stimulus by rubbing the internodes for about 10 s once or twice daily, elongation was significantly retarded. Plants of Cucurbita pepo Pisum sativum and Triticum aestivum did not exhibit any such response. The initial response to rubbing was very rapid, elongation stopping less than 3 min after application of the stimulus. When the stimulus was discontinued after 7 days, elongation accelerated, reaching a normal or supernormal rate within 3 or 4 days. Mechanical stimulation also affected aspects of growth and development other than stem elongation. In Mimosa pudica, flower bud production was retarded, as was the growth of the tendrils, leaves, and petioles in Bryonia dioica. It is suggested that this response be called thigmomorphogenesis, and that it represents an adaptation designed to protect plants from the stresses produced by high winds and moving animals. Some evidence indicates that thigmomorphogenesis may be mediated by ethylene.

Physiological Studies on Pea Tendrils: VI. The Characteristics of Sensory Perception and Transduction.

Tendrils may be said to possess a sense of touch, and the direction and amplitude of the coiling response can be used to define the characteristics of this sense. These characteristics are, first, that the tendril will coil only in response to ventral mechanical stimulation, that this coiling can be inhibited by subsequent dorsally presented stimulation, and that dorsal stimulation alone causes no coiling. This phenomenon seems to be due to some asymmetry in the response system. Second, the nature of the response is always determined by the location (i.e., dorsal or ventral) of the last stimulation the tendril experienced. Third, the ability of dorsally presented stimulation to reverse ventrally stimulated coiling is gradually lost. Complete escape from reversibility is attained if the interval between ventral and dorsal stimulation reaches 9 minutes. Fourth, the magnitude of response is determined by both the number and the frequency of the stimuli. Both ventrally stimulated coiling and dorsally stimulated inhibition of coiling can be temporarily stopped by a 9-minute cold break at 10 C, given immediately after stimulation. As soon as the tendrils are restored to room temperature, they proceed to respond to the stimulus.The pulling ability of the tendrils generated by contact coiling, as measured by an electronic monitoring system, is of the order of 6 milligrams per minute. Whenever these two factors have been compared, pulling weight parallels contact coiling, regardless of treatment.The relationship between the stimulus and the response appears to follow rules very similar to those followed by various sensory response systems in animals. It is therefore proposed that many of these systems may have functional characteristics in common.

Physiological Studies on Pea Tendrils: VII. Evaluation of a Technique for the Asymmetrical Application of Ethylene.

A technique has been devised for the asymmetrical application of ethylene to specific surfaces of plant tissue. 2-Chloroethylphosphonic acid (CEPA) was dissolved in a phosphate buffer (pH 6.5) containing Tween-20 or dimethylsulfoxide as adjuvant. Ethylene evolution from tendrils of Pisum sativum cv. Alaska was greater during coiling than when they were at rest; and via topical application to the ventral surface, CEPA was able to stimulate contact coiling. Within 1 day of application of CEPA, the tendrils showed symptoms of senescence. It is concluded that ethylene participates in the control of contact coiling stimulated by touch, and it is suggested that this control may be exerted via permeability changes in the membranes of the motor cells.

On heliotropism in tendrils of Pisum sativum: A response to infrared irradiation.

In 1876, Darwin observed that tendrils of Pisum sativum oriented the long axis of their circumnutational sweep to keep it approximately normal to the direction of the sun's rays. Using various types of irradiation sources, the present study confirms Darwin's findings. Although blue light slightly increases the rate of circumnutation, only infrared irradiation (i.e. heat), effects the reorientation. The response can therefore be termed Diathermotropic. Diathermotropism in circumnutating tendrils is probably a device to bend the leaves of the elongating weak-stemmed plant away from the shade and toward the sun.