[Cyanobacterial community formed during the degradation of apogeotropic roots of cycads].
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Biodegradation, Environmental↗
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Results for “Root physiology”
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Localization of flavonoid enzymes in Arabidopsis roots.
Immunofluorescence and immuno-electron microscopy have been used to test the hypothesis that flavonoid metabolism is organized as a membrane-associated enzyme complex. The cellular and subcellular locations of chalcone synthase (CHS) and chalcone isomerase (CHI), the first two enzymes of this pathway, were examined in Arabidopsis roots. High levels of both enzymes were found in the epidermal and cortex cells of the elongation zone and the root tip, consistent with the accumulation of flavonoid endproducts at these sites. Co-localization of CHS and CHI was observed at the endoplasmic reticulum and tonoplast in these cells, and also in electron-dense regions that are, as yet, unidentified. In addition, a striking asymmetric distribution was observed for these enzymes in cortex cells of the elongation zone, which may provide clues about the physiological function of flavonoids in roots. The accumulation of CHS and CHI was also examined in tt7(88), a mutant in the gene for flavonoid 3'-hydroxylase (F3'H), which has been postulated to serve as a membrane anchor for the flavonoid enzyme complex. CHS and CHI accumulated to lower levels in cortex cells and higher levels in epidermal cells in the roots of this mutant as compared with wild-type plants. Moreover, the electron-dense regions containing these two enzymes were not observed. However, localization of CHS and CHI to the ER and tonoplast did not appear to be affected, suggesting that other proteins may function in recruiting the "soluble" flavonoid enzymes to membranes. Staining of flavonoid endproducts with DPBA was consistent with expression of CHS and CHI in these seedlings.
Acyltransferases↗
Ventriculo-aortic junction in human root. A geometric approach.
With advances in tissue engineering and improvement of surgical techniques, stentless biological valves and valve-sparing procedures have become alternatives to traditional aortic valve replacement with stented bioprostheses or mechanical valves. New surgical techniques preserve the advantages of native valves but require better understanding of the anatomical structure of the aortic root. Silicone rubber was injected in fresh aortic roots of nine human cadavers under the physiological closing pressure of 80 mmHg. The casts reproduced every detail of the aortic root anatomy and were used to digitize 27 leaflet attachment lines (LALs) of the aortic valves. LALs were normalized and described with a mathematical model. LALs were found to follow a pattern with the right coronary being the largest followed by the non-coronary and then the left coronary. During diastole, the aortic valve LAL can be described by an intersection between a created tube and an extruded parabolic surface. This geometrical definition of the LAL during end diastole gives a better understanding of the aortic root anatomy and could be useful for heart valve design and improvement of aortic valve reconstruction technique.
Adult↗
Metabolic and fiber size properties of cat tibialis anterior motor units.
The variability among single muscle fiber enzymatic activities and fiber size within a motor unit was studied in the cat tibialis anterior (TA) muscle. Fourteen units were isolated for physiological testing using standard ventral root filament stimulation techniques, and the muscle fibers of these units were identified by glycogen depletion. The cross-sectional areas, succinate dehydrogenase (SDH) and alpha-glycerolphosphate dehydrogenase (GPD) activities, and the relative alkaline myofibrillar adenosine triphosphate staining densities of a sample of glycogen-depleted and -nondepleted muscle fibers were determined using quantitative histochemical techniques. Each of the unit types previously identified to be present in the TA, based on physiological criteria, were represented by the sample population. The variability among the fibers of a unit was significantly more than the variability among repeated measures on a single fiber for cross-sectional area and SDH and GPD activities. The mean coefficients of variation for SDH and GPD activity within motor unit fibers were 29 and 56%, respectively, whereas the variability between fibers of different units within a muscle was significantly greater (53 and 69%, respectively). Additionally, the mean coefficient of variation for cross-sectional area among motor unit fibers was less than that among fibers not depleted of glycogen (25 vs. 46%). These data suggest that although there is clear evidence for some level of neural control of the properties of a muscle unit (variation within a unit was less than the variation across units), this control is not complete, since the variability among fibers of a single unit was significantly more than the variability found between repeated measurements on a single fiber.
Animals↗
Anorectal continence and bladder function. Effects of major sacral resection.
The effect of sacral resection up to S-2 has been investigated in two patients with "chordomas," surgical division of the spinal roots was unilateral and bilateral, respectively. Anal manometry, electromyography of the sphincters, and the ascertaining of tactile, thermic, and painful stimuli perception in the perineum and anal canal were executed to determine the effects of denervation on anorectal continence. Vesical function was tested by vesical manometry. Results differ strongly between the two patients: the first, with unilateral loss of S-2, has perfect anorectal continence. The second, with bilateral loss of S-2, is incontinent and unable to discriminate rectal contents. It is sufficient to retain only one S-2 root for the maintenance of physiologic continence, including distinction between different types of bowel contents (gaseous or solid) passing through the anal canal. The same is true concerning bladder function.
Anal Canal↗
Intrinsic and environmental response pathways that regulate root system architecture.
Root system development is an important agronomic trait. The right architecture in a given environment allows plants to survive periods of water of nutrient deficit, and compete effectively for resources. Root systems also provide an optimal system for studying developmental plasticity, a characteristic feature of plant growth. This review proposes a framework for describing the pathways regulating the development of complex structures such as root systems: intrinsic pathways determine the characteristic architecture of the root system in a given plant species, and define the limits for plasticity in that species. Response pathways co-ordinate environmental cues with development by modulating intrinsic pathways. The current literature describing the regulation of root system development is summarized here within this framework. Regulatory pathways are also organized based on their specific developmental effect in the root system. All the pathways affect lateral root formation, but some specifically target initiation of the lateral root, while others target the development and activation of the lateral root primordium, or the elongation of the lateral root. Finally, we discuss emerging approaches for understanding the regulation of root system architecture.
Cell Cycle↗
Plant-induced changes in soil chemistry do not explain differences in uranium transfer.
A greenhouse experiment was set up with maize, ryegrass, Indian mustard, wheat and pea to evaluate to what extent differences in uranium (U) transfer factors can be explained by root-mediated changes in selected soil properties. The experiment involved an acid and an alkaline soil contaminated with (238)U. U soil-to-shoot transfer factors (TFs) ranged between 0.0005 and 0.021 on the acid soil and between 0.007 and 0.179 on the alkaline soil. Indian mustard showed the highest U uptake in shoots and maize the lowest. The root TFs, only available for the acid soil, ranged from 0.58 for maize and Indian mustard to 1.38 for ryegrass. The difference in U uptake between the two soils and the five plants was only partially explained by the different initial U concentrations in soil solution or differences in soil properties in the two soils. However, we obtained a significant relation for differences in shoot TFs observed between the two soils when relating shoot TFs with concentration of UO(2)(2+) and uranyl carbonate complexes in soil solution (R(2)=0.88). The physiological mechanisms by which root-to-shoot U transfer is inhibited or promoted seemed at least as important as the plant-induced changes in soil characteristics in determining soil-to-shoot TFs.
Plants↗
Inactivation by saliva and serum of the antimicrobial activity of some commonly used root canal sealer cements.
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Anti-Infective Agents, Local↗
Citric acid demineralization of cementum and dentin: the effect of application pressure.
Previous work has shown that a 25-30% citric acid solution was the most effective concentration with which to demineralize dentin. The purpose of this investigation was to study the topography, using a scanning electron microscope, of root surfaces treated with a 30% citric acid solution using various application pressures. 20 freshly extracted human teeth were collected and stored in physiologic saline at room temperature. 3 root specimens, approximately 3x5x5 mm in size, were prepared from the coronal periodontally healthy area of each tooth. 30 specimens were root planed to expose dentin (dentin group) while the remaining 30 specimens were lightly scaled to remove periodontal soft tissue (cementum group). A freshly made 30% citric acid (CA) solution, (pH = 1.60), was applied to each of the experimental areas. Cotton pellets soaked in the citric acid solution were either placed (CAP), lightly rubbed (CAR) or heavily burnished (CAB) on the prepared root surface for 3 min. Pellets were resoaked every 30 s. The root sections were rinsed, fixed in glutaraldehyde, dehydrated in graded ethanol, critically point dried in liquid CO2 and sputter coated in gold. The treated surfaces were assessed for fibril tufting using scanning electron microscopy. Assessment was made of: (i) the % of surface area tufted; (ii) tufting depth (0-3); (iii) tufting density (1-3). Results of the study showed significantly more tufted surface area and greater tufting depth on both dentin and cementum for CAR and CAB compared to CAP. CAP produced a flat/mat fibril surface with no evidence of tufting.(ABSTRACT TRUNCATED AT 250 WORDS)
Acid Etching, Dental↗
Bacteriologic evaluation of the efficacy of mechanical root canal instrumentation in endodontic therapy.
The presence of bacteria in 17 single-rooted teeth, with periapical lesions, was studied throughout a whole period of treatment. The root canals were irrigated with physiologic saline solution during instrumentation. No antibacterial solutions or dressings were used. Bacteria were found in all initial specimens from the teeth (median number of bacterial cells 4 x 10(5), range 10(2) - 10(7)) and the number of strains in the specimens ranged from 1 to 10.88% of the strains were anaerobic. The most commonly isolated species were: Peptostreptococcus micros, Peptostreptococcus anaerobius, Fusobacterium nucleatum, Bacteroides oralis, Bacteroides melaninogenicus subsp intermedius and Eubacterium alactolyticum. Mechanical instrumentation reduced the number of bacteria considerably. Specimens taken at the beginning of each appointment usually contained 10(4) - 10(6) bacterial cells and at the end 10(2) - 10(3) fewer. Bacteria were eliminated from the root canals of eight teeth during the treatment. In seven root canals bacteria persisted despite treatment on five successive occasions. There was no evidence that specific microorganisms were implicated in these persistent infections. Teeth where the infection persisted despite being treated five times were those with a high number of bacteria in the initial sample.
Adolescent↗
[Physiological approach to peripheral neuropathy. Conventional nerve conduction studies and magnetic motor root stimulation].
In this communication, I first show some points we should mind in the conventional peripheral nerve conduction studies and later present clinical usefulness of motor root stimulation for peripheral neuropathy. CONVENTIONAL NERVE CONDUCTION STUDIES (NCS): The most important point revealed by the conventional NCSs is whether neuropathy is due to axonal degeneration or demyelinating process. Precise clinical examination with this neurophysiological information leads us to a diagnosis and treatment. Poor clinical examination makes these findings useless. Long standing axonal degeneration sometimes induces secondary demyelination at the most distal part of involved nerves. On the other hand, severe segmental demyelination often provokes secondary axonal degeneration at distal parts to the site of demyelination. These secondary changes show the same abnormal neurophysiological findings as those of the primary involvement. We should be careful of this possibility when interpreting the results of NCS. NCS of sensory nerves is not good at revealing demyelinating process. Mild temporal dispersion of potentials often reduces an amplitude of SNAP or loss of responses, which usually suggests axonal degeneration, because of short duration of sensory nerve potentials. MOTOR ROOT STIMULATION IN PERIPHERAL NEUROPATHY: Magnetic stimulation with a coil placed over the spine activates motor roots and evokes EMG responses from upper and lower limb muscles. The site of activation with this method was determined to be where the motor roots exit from the spinal canal (intervertebral foramina) (J Neurol Neurosurg Psychiatry 52 (9): 1025-1032, 1989) because induced currents are very dense at such a foramen made by electric resistant bones. In several kinds of peripheral neuropathy, this method has been used to detect a lesion at a proximal part of the peripheral nerves which can not be detected by the conventional NCSs. I present a few cases in whom motor root stimulation had a clinical merit. In a patient with neuralgic amyotrophy, motor root stimulation disclosed a conduction block between the cervical intervertebral foramen and brachial plexus which was not detected by conventional NCSs. Motor root stimulation clearly revealed demyelination in a patient with CIDP in whom sural nerve biopsy findings suggested axonal degeneration, that must be secondary to demyelination. In a patient with tomacular neuropathy, magnetic stimulation revealed conduction delay in the spinal nerve within the spinal canal (Clin Neurol (Jap), 28: 447-452, 1988). Based on the above results, combination of NCSs and magnetic motor root stimulation must brush up the neurophysiological approach to peripheral neuropathy.
Electric Stimulation↗
[Effect of subarachnoidal perfusion of frozen physiological saline on changes in action potentials of the thalamus and dorsal root].
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Action Potentials↗
Effects of acid mist on needles from mature Sitka spruce grafts. Part II. Influence of developmental stage, age and needle morphology on visible damage.
Mature grafts of five Sitka spruce (Picea sitchensis (Bong.) Carr.) clones were exposed to simulated acid mist comprising an equimolar mixture of H(2)SO(4) and NH(4)NO(3) (1.6 and 0.01 mol m(-3)) at pH 2.5 and 5.0. Mist was applied to potted plants growing in open-top chambers on consecutive days, four times a week, at a precipitation equivalent of 1 mm per day. The total exposure to polluted mist was equivalent to three times that measured at an upland forest in SE Scotland. The aim of the experiment was to characterize the response of juvenile foliage produced by physiologically mature grafts (on seedling root stock) and compare it with the behaviour of juvenile foliage on seedlings. Development of visible foliar damage was followed through the growing season. Measurements of needle length, diameter, weight, surface area, surface was weight and wettability were made on current year needles to determine whether particular foliar characteristics increased susceptibility to injury. Significant amounts (> 10%) of visible needle damage was observed on only one of the five clones. Damage was most severe on the clone with the most horizontal branch and needle habit, but over the five clones there was no relationship between angle of branch display and damage. Likewise no combination of needle characteristics (length, width, area, amount of wax) was indicative of potential susceptibility. A comparison with previous acid misting experiments using seedlings suggests that juvenile foliage on physiologically mature trees is equally susceptible to visible injury as juvenile seedling foliage. Data of budburst differed among clones, and in this experiment exerted the over-riding influence on development of injury symptoms. Foliage exposed to a combination of strong acidity and high sulphate concentrations over the few weeks immediately following budburst suffered most visible injury. The absence of significant amounts of visible damage in UK forests probably reflects the general low susceptibility to visible injury of Sitka spruce exposed to acid mist.
Journal Article↗
Physiological relevance of T-tube model parameters with emphasis on arterial compliances.
The T-tube model of systemic arterial circulation was examined with respect to the physiological relevance of model parameters. root aortic pressure [Pao(t)] and flow [Qao(t)] and descending aortic flow [Qb(t)] were measured in anesthetized, open-chest dogs under control conditions, during inflation of a balloon positioned in the left external iliac artery (n = 5), and during infusion of vasoactive drugs nitroprusside (NTP, n = 4) and phenylephrine (PHL, n = 5). With Pao(t) as the input, the model accurately predicted both Qao(t) and Qb(t) under all conditions (r2 > 0.96). The balloon inflation data established the ability of the model to discriminate between proximal and distal arterial mechanical properties. Furthermore, proximal properties (i.e., tube characteristic impedances and transit times) were independent of distal properties such as terminal compliances and resistances (or equivalently, wave reflections). The effects of NTP and PHL were pharmacologically consistent and served to further validate this model. NTP primarily affected distal (load) properties, whereas PHL altered both load and tube parameters. Physiological interpretation of model parameters, particularly compliance, is also discussed. The ability of the model to correctly discriminate between proximal and distal arterial properties is relevant because these properties may affect cardiovascular function differently.
Animals↗
[Studies on rhubarb root grown in the Netherlands. III. The structure of the glycosides of rhein].
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Anthraquinones↗
Chemical and biological studies on 1,2-dihydro-s-triazines. XI. Inhibition of root growth and its reversal by citrovorum factor.
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Biological Phenomena↗
Iron-mediated control of the basic helix-loop-helix protein FER, a regulator of iron uptake in tomato.
Root iron mobilization genes are induced by iron deficiency downstream of an unknown signaling mechanism. The FER gene, encoding a basic helix-loop-helix domain protein and putative transcription factor, is required for induction of iron mobilization genes in roots of tomato (Lycopersicon esculentum). To study upstream regulatory events of FER action, we examined the control of FER gene and FER protein expression in response to iron nutritional status. We analyzed expression of the FER gene and FER protein in wild-type plants, in mutant plants with defects in iron uptake regulation, and in 35S transgenic plants that overexpressed the FER gene. An affinity-purified antiserum directed against FER epitopes was produced that recognized FER protein in plant protein extracts. We found that the FER gene and FER protein were consistently down-regulated in roots after generous (100 mum, physiologically optimal) iron supply compared to low (0.1 mum) and sufficient (10 mum) iron supply. FER gene and FER protein expression were also occasionally down-regulated at sufficient compared to low iron supply. Analysis of FER protein expression in FER overexpression plants, as well as cellular protein localization studies, indicated that FER was down-regulated by high iron at the posttranscriptional level. The FER protein was targeted to plant nuclei and showed transcriptional activation in yeast (Saccharomyces cerevisiae). FER protein regulation in the iron accumulation mutant chloronerva indicated that FER protein expression was not directly controlled by signals derived from iron transport. We conclude that FER is able to affect transcription in the nucleus and its action is controlled by iron supply at multiple regulatory levels.
Cell Nucleus↗
The pharmacology and ionic dependency of amino acid responses in the frog spinal cord.
1. The isolated frog spinal cord was used to study the action of amino acids and their antagonists on primary afferent terminals and motoneurones. The direct effects of these substances were observed by bathing the cord in 20 mM magnesium sulphate (thus blocking synaptic transmission) and recording the polarization level of the dorsal and ventral roots.2. gamma-Aminobutyric acid (GABA) and glutamic acid depolarized the dorsal root and reduced dorsal-root potentials, while glycine produced only weak and variable effects. Glutamic acid also depolarized the ventral root; GABA usually produced either a hyperpolarization or had little effect, while glycine caused variable effects.3. Bicuculline and picrotoxin antagonized all the synaptic potentials recorded on the dorsal root, as well as the GABA responses on both dorsal and ventral roots.4. All the synaptic potentials examined remained and were markedly prolonged in the absence of external chloride except the ventral root-dorsal root potential. Replacement of the physiologic complement of chloride during chloride-free perfusion restored the potentials to their original time courses.5. Depolarizing amino acid responses remained in the absence of external chloride, while hyperpolarizing responses were reversed into depolarizations. Return to normal Ringer solution re-established the hyperpolarizations.6. Removal of external sodium reversibly abolished the amino acid depolarizations but had little effect on the depolarizations in response to applications of high external potassium concentrations.7. The results support the hypotheses (a) that GABA mediates presynaptic inhibition by depolarizing primary afferent terminals and (b) that the GABA-mediated depolarization is sodium dependent.8. The results also indicate that GABA utilizes different ionic mechanisms to mediate presynaptic inhibition (sodium) and post-synaptic inhibition (chloride) in the amphibian (and presumably in the mammal).
Action Potentials↗