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At least 379 records · Page 21Linked to original sources
PubMed2003

Identification of water-deficit responsive genes in maritime pine (Pinus pinaster Ait.) roots.

Root adaptation to soil environmental factors is very important to maritime pine, the main conifer species used for reforestation in France. The range of climates in the sites where this species is established varies from flooded in winter to drought-prone in summer. No studies have yet focused on the morphological, physiological or molecular variability of the root system to adapt its growth to such an environment. We developed a strategy to isolate drought-responsive genes in the root tissue in order to identify the molecular mechanisms that trees have evolved to cope with drought (the main problem affecting wood productivity), and to exploit this information to improve drought stress tolerance. In order to provide easy access to the root system, seedlings were raised in hydroponic solution. Polyethylene glycol was used as an osmoticum to induce water deficit. Using the cDNA-AFLP technique, we screened more than 2500 transcript derived fragments, of which 33 (1.2%) showed clear variation in presence/absence between non stressed and stressed medium. The relative abundance of these transcripts was then analysed by reverse northern. Only two out of these 33 genes showed significant opposite behaviour between both techniques. The identification and characterization of water-deficit responsive genes in roots provide the emergence of physiological understanding of the patterns of gene expression and regulation involved in the drought stress response of maritime pine.

Blotting, Northern↗
PubMed2002

Mapping QTLs regulating morpho-physiological traits and yield: case studies, shortcomings and perspectives in drought-stressed maize.

Comparative analysis of a number of studies in drought-stressed maize (Zea mays L.) reporting quantitative trait loci (QTLs) for abscisic acid concentration, root characteristics, other morpho-physiological traits (MPTs) and grain yield (GY) reveals their complex genetic basis and the influence of the genetic background and the environment on QTL effects. Chromosome regions (e.g. near umc11 on chromosome 1 and near csu133 on chromosome 2) with QTLs controlling a number of MPTs and GY across populations and conditions of different water supply have been identified. Examples are presented on the use of QTL information to elucidate the genetic and physiological bases of the association among MPTs and GY. The QTL approach allows us to develop hypotheses accounting for these associations which can be further tested by developing near isogenic lines (NILs) differing for the QTL alleles. NILs also allow for a more accurate assessment of the breeding value of MPTs and, in some cases, may allow for the map-based cloning of the gene(s) underlying the QTL. Although QTL analysis is still time-consuming and resource-demanding, its integration with genomics and post-genomics approaches (e.g. transcriptome, proteome and metabolome analyses) will play an increasingly important role for the identification and validation of candidate genes affecting MPTs and GY.

Abscisic Acid↗
PubMed2002

Dexamethasone decreases blood flow in normal nerves and dorsal root ganglia.

STUDY DESIGN: An experimental physiologic and histologic study of dexamethasone effects on peripheral nerves. OBJECTIVE: To characterize the effect of topically applied 0.4% dexamethasone on acute changes in nerve blood flow and subsequent histologic changes in rat sciatic nerve fibers. SUMMARY OF BACKGROUND DATA: Dexamethasone is an anti-inflammatory glucocorticoid used clinically to reduce the neural consequences of inflammation. Several reports of accidental injury to nerves after steroid injections have raised questions about the mechanisms involved in dexamethasone-induced neurotoxic injury. METHODS: Nerve blood flow studies using a laser Doppler flowmeter were conducted in animals with stable temperature and arterial pressure. Dexamethasone 0.4%, 0.1 mL was applied topically to rat sciatic nerve in the following protocol groups: 1) nerve blood flow recording every 5 minutes for 30 minutes, and 2) initial nerve blood flow recording and repeat recording at 4 hours. Three additional animals had 30-minute nerve blood flow recordings in which normal saline was substituted for dexamethasone; these animals were used for control and to assure that the experimental preparation was viable throughout the observational period. Additional groups of two animals each received dexamethasone but were used only for neuropathologic observation at 2, 4, and 6 days after treatment. Neuropathologic studies were conducted on glutaraldehyde-fixed, plastic-embedded tissue. RESULTS: Application of saline to the exposed sciatic nerves did not significantly change nerve blood flow from baseline values. Nerve blood flow values remained constant throughout the observational period. Dexamethasone, however, significantly reduced nerve blood flow in both the 30-minute and 4-hour groups. Some animals showed an initial transient increase in blood flow before nerve blood flow began to steadily decline to the final values reported. Neuropathologic changes were minimal and consisted only of edema and occasional subperineurial activation of Schwann cells. No demyelination or degeneration was seen. CONCLUSION: Dexamethasone causes statistically significant reductions in normal nerve blood flow at 30 minutes and 4 hours after topical application; however, the reduction is on average below the threshold for causing ischemic changes in the structure of peripheral nerve fibers.

Administration, Topical↗
PubMed2025

Integrative spatial transcriptomic analysis pinpoints the role of the ferroxidase, TaMCO3, in wheat root tip iron mobilization.

Roots play a critical role in the sensing and absorption of essential minerals from the rhizosphere. Iron (Fe) deficiency, for example, triggers a well-known series of physiological and molecular responses within roots that facilitate uptake, which differs between monocots and dicots. In monocots, little is known about the molecular responses that occur within specific root development zones in response to iron deprivation, and how these differences result in overall nutrient uptake. Here, we conducted a transcriptome analysis of wheat root tips under Fe deficiency (-Fe) and performed a comparative transcriptome analysis with the previous datasets generated from the whole root. Gene ontology analysis of differentially expressed genes highlighted the significance of oxidoreductase activity and metal/ion transport in the root tip, which are critical for Fe mobilization. Interestingly, wheat, an allohexaploid species consisting of three different genomes (A, B, and D) displayed varying gene expression levels arising from the three genomes that contributed to similar molecular functions. Detailed analysis of oxidoreductase function at the root tip revealed multiple multicopper oxidase (MCO) proteins, such as Fe-responsive TaMCO3, that likely contribute to the overall ferroxidase activity. Further characterization of TaMCO3 shows that it complements the yeast FET3 mutant and rescues the -Fe sensitivity phenotype of Arabidopsis atmco3 mutants by enhancing vascular Fe loading. Transgenic wheat lines overexpressing TaMCO3 exhibited increased root Fe accumulation and improved tolerance to -Fe by augmenting the expression of Fe-mobilizing genes. Our findings highlight the role of spatially resolved gene expression in -Fe responses, suggesting strategies to reprogram cells for improved nutrient stress tolerance.

Triticum↗
PubMed2006

[External root resorption].

Root resorption may be a physiological (resorption of deciduous teeth) or a pathological process (resorption of permanent teeth). In the latter case an external and an internal form of resorption can be distinguished. Root resorption may occur on one tooth or on several teeth within a dentition and it may be caused by trauma, periodontitis, orthodontic treatment, internal bleaching, cysts, tumors, or by stimuli from a necrotic dental pulp. Current knowledge concerning the pathogenesis of root resorption and therapeutic approaches are presented. For cervical resorption, it is assumed that the stimulus for the resorbing cells originates from the bacteria within the gingival sulcus and along the affected root surface. The case presented here was initially diagnosed as chronic periodontitis of medium severity. Scaling and root planing were performed resulting in a significant improvement of the periodontal status. Two years later, following a period of irregular recall visits, the patient presented with large areas of cervical resorption on teeth 36 and 37 which made it impossible to preserve these teeth. After another six months, teeth 34 and 35 showed deep destruction caused by external root resorption, mandating the extraction of these teeth as well. Fourteen months later, external root resorptions were evident on teeth 32 and 33, and at the same time, a recurrence of the chronic periodontitis was noted. Periodontal therapy was performed under a systemic antibiotic regime. It was possible to preserve teeth 32 and 33 through surgical crown lengthening procedures. No additional resorption has been observed ever since.

Adult↗
PubMed2003

The evolution of polar fish hemoglobin: a phylogenetic analysis of the ancestral amino acid residues linked to the root effect.

Originating from a benthic ancestor, the suborder Notothenioidei (the dominant fish fauna component of the Antarctic sea) underwent a remarkable radiation, which led notothenioids to fill several niches. The ecological importance of notothenioids in Antarctica and their biochemical adaptations have prompted great efforts to study their physiology and phylogeny, with special attention to the evolutionary adaptation of the oxygen-transport system. We herewith report the evolutionary history of alpha- and beta-globins under the assumption of the molecular clock hypothesis as a basis for reconstructing the phylogenetic relationships among species. These studies have been extended to fish species of other latitudes, including the Arctic region. The northern and southern polar oceans have very different characteristics; indeed, in many respects the Antarctic and Arctic ichthyofaunas are more dissimilar than similar. Our results show that the inferred phylogeny of Arctic and Antarctic globins is different. Taking advantage of the wealth of information collected on structure and function of hemoglobins, we have attempted to investigate the evolutionary history of an important physiological feature in fish, the Root effect. The results suggest that the amino acid residues reported to play a key role in the Root effect may be regarded as ancestor characters, but the lack of this effect in extant species can hardly be associated with the presence of synapomorphies.

Adaptation, Physiological↗
PubMedDate not supplied

[The dynamics of hormonal status of developing red beet root (Beta vulgaris L.) in correlation with the dynamics of sugar accumulation].

We studied the dynamics of phytohormone levels (indole-3-acetic acid, abscisic acid, cytokinins, and gibberellin-like substances) in red beet (Beta vulgaris L.) roots at different developmental stages in comparison with the data on the dynamics of sugar accumulation in order to test possible hormonal regulation of sugar accumulation. The obtained data suggest the involvement of cytokinins and gibberellin-like substances in the control of sugar accumulation in the roots, while indole-3-acetic acid, abscisic acid, and gibberellin-like substances can control the outflow. The data on the dynamics of phytohormone levels shed light on their specific physiological role in red beet root development.

Beta vulgaris↗
PubMed1990

Inverse Relationship between Polyamine Levels and the Degree of Phenotypic Alteration Induced by the Root-Inducing, Left-Hand Transferred DNA from Agrobacterium rhizogenes.

Floral induction in plants is a paradigm for signal perception, transduction, and physiological response. The introduction of root-inducing, left-hand transferred DNA (Ri T-DNA) into the genomes of several plants results in modifications of flowering (D Tepfer [1984] Cell 47: 959-967), including a delay in flowering in tobacco (Nicotiana tabacum). Conjugated polyamines are markers for flowering in numerous species of plants. In tobacco their accumulation is correlated with the onset of flowering (F Cabanne et al. [1981] Physiol Plant 53: 399-404). Using tobacco, we have explored the possibility of a correlation between the expression of Ri TL-DNA and changes in polyamine metabolism. We made use of two levels of phenotypic change, designated T and T', that retard flowering by 5 to 10 and 15 to 20 days, respectively. We show that delay in flowering is correlated with a reduction in polyamine accumulation and with a delay in appearance of conjugated polyamines, and we propose that genes carried by the Ri TL-DNA intervene either directly in polyamine metabolism or that polyamine metabolism is closely linked to direct effects of Ri T-DNA expression.

Journal Article↗
PubMed2002

Detection of lumbosacral nerve root compression with a novel composite nerve conduction measurement.

STUDY DESIGN: Multivariate logistic regression techniques were used to develop a composite nerve conduction measurement that detects lumbosacral (L5, S1, or both) nerve root compression. OBJECTIVES: To evaluate the diagnostic efficacy of a composite nerve conduction measurement for detection of lumbosacral nerve root compression. SUMMARY OF BACKGROUND DATA: Nerve root involvement is characterized by clinical abnormalities and confirmed by radiologic and electrodiagnostic studies. Imaging studies visualize structural abnormalities; however, they are associated with high false-positive rates. Electrodiagnostic methods assess the physiologic integrity of the nerve roots. One form of electrodiagnostic testing, nerve conduction studies, is widely used for evaluation of musculoskeletal and neuromuscular complaints. Although similar clinical value is expected for the evaluation of nerve root compromise, prior applications of nerve conduction studies have yielded widely varying results. METHODS: Two groups of subjects were compared. The L5-S1 compression group was composed of 25 patients with magnetic resonance imaging-confirmed lumbosacral (L5, S1, or both) nerve root compression and symptoms in the appropriate segmental distribution. The majority of subjects (22) had at least one of the following findings on physical examination: positive straight-leg raise test, diminished ankle reflexes, sensory loss, or weakness. The control group consisted of 35 asymptomatic individuals with no history of radiculopathy or potentially confounding neuropathology. The posterior tibial and deep peroneal nerves were evaluated bilaterally in all study subjects using standard nerve conduction procedures, which consisted of the measurement of distal motor latencies and F-wave latencies that assess nerve root pathophysiology. A composite nerve conduction measurement was determined using multivariate logistic regression analysis. The efficacy of the composite measurement was assessed by receiver operating characteristic curve analysis and by the diagnostic sensitivity and specificity. RESULTS: Five F-wave latency parameters (peroneal mean F-wave latency, odds ratio = 0.42; peroneal seventh F-wave latency decile, odds ratio = 2.71; tibial mean F-wave latency, odds ratio = 8.90; tibial first F-wave latency decile, odds ratio = 0.47; tibial maximum F-wave latency, odds ratio = 0.44) were found to be predictive of nerve root compression. A composite nerve conduction measurement, NC composite, constructed from these five parameters (NC composite = exp(phi)/(1 + exp(phi)), phi = -31.2 + 1.0 * Per7 Decile - 0.88 * PerMean + 2.2 * TibMean - 0.88 * Tib1 Decile - 0.83 * TibMax) yielded an area under the receiver operating characteristic curve of 0.91. At a threshold of 0.20, NC composite had a diagnostic specificity of 84.3% and a sensitivity of 83.3%. CONCLUSION: This preliminary study suggests that a novel composite nerve conduction measurement, based on F-wave latency parameters, may be highly effective at detecting magnetic resonance imaging-confirmed lumbosacral nerve root compression. Because these measurements provide objective evidence of functional nerve root compromise and are noninvasive, they may be of diagnostic value to clinicians evaluating patients presenting with low back and leg pain.

Adult↗
PubMedDate not supplied

Idiopathic external root resorption associated to hypercalciuria.

Although external root resorption (ERR) is a physiological process in deciduous dentition, it is very infrequent in permanent dentition - where the phenomenon is related to the existence of inadequate occlusal forces, periodontal pathology and microtraumatisms, etc. However, in many cases root resorption cannot be attributed to any concrete cause; such cases are defined as idiopathic external root resorption (IERR). Epidemiological studies have found that the underlying cause can only be established in 5% of all ERR. The present study describes three cases of IERR with different degrees of involvement and associated to mild calciuria and a history of nephrolithiasis. Hypercalciuria with normal blood calcium levels is usually idiopathic and exhibits a familial trait, with a prevalence of 20-40 cases per 1,000 individuals in adults. A form of hypercalciuria associated to nephrolithiasis with a mutation of the CLCN5 gene has been identified, involving low molecular weight proteinuria - though this mutation has not been uniformly demonstrated in most cases of idiopathic hypercalciuria. The peculiarity of the cases described in the present study is attributable to the coexistence of IERR with normocalcemic hypercalciuria and nephrolithiasis - thus pointing to the need for in-depth evaluation of the possible association of these three clinical situations.

Adolescent↗
PubMed1987

Astrocytes block axonal regeneration in mammals by activating the physiological stop pathway.

Regenerating sensory axons in the dorsal roots of adult mammals are stopped at the junction between the root and spinal cord by reactive astrocytes. Do these cells stop axonal elongation by activating the physiological mechanisms that normally operate to stop axons during development, or do they physically obstruct the elongating axons? In order to distinguish these possibilities, the cytology of the axon tips of regenerating axons that were stopped by astrocytes was compared with the axon tips that were physically obstructed at a cul-de-sac produced by ligating a peripheral nerve. The terminals of the physically obstructed axon tips were distended with neurofilaments and other axonally transported structures that had accumulated when the axons stopped elongating. By contrast, neurofilaments did not accumulate in the tips of regenerating axons that were stopped by spinal cord astrocytes at the dorsal root transitional zone. These axo-glial terminals resembled the terminals that axons make on target neurons during normal development. On the basis of these observations, astrocytes appear to stop axons from regenerating in the mammalian spinal cord by activating the physiological stop pathway that is built into the axon and that normally operates when axons form stable terminals on target cells.

Animals↗
PubMed2001

Phytoextraction of Cd and Pb and physiological effects in potato plants (Solanum tuberosum var. Spunta): importance of root temperature.

Three consecutive years of field experiments were carried out to investigate the effect of different root-zone temperatures, induced by the application of mulches, on the concentration and accumulation of Cd and Pb and on bioindicators (chlorophylls, catalase, peroxidase and cell wall fractions) in different organs of potato plants (roots, tubers, stems, and leaflets). Four different plastic covers were employed (T1, transparent polyethylene; T2, white polyethylene; T3, white and black coextruded polyethylene, and T4, black polyethylene), using uncovered plants as the control (T0). The different treatments had a significant effect on the mean root-zone temperatures (T0 = 16 degrees C, T1 = 20 degrees C, T2 = 23 degrees C, T3 = 27 degrees C, and T4 = 30 degrees C) and induced significantly different responses in the Cd and Pb concentrations and phytoaccumulation, with T2 (23 degrees C) and T3 (27 degrees C) giving high concentrations of Cd in the roots and low concentrations in other organs. In relation to Pb, T2 and T3 reached higher levels in the tubers and lower levels in the roots, stems, and leaves. In terms of phytoaccumulation, the roots and tubers were the most effective organs for Cd and Pb. On the other hand, the highest values of peroxidase and catalase activities were obtained for T3. In addition, most of the carbohydrate fractions in both the roots and the tubers were highest for T3. Meanwhile, the lowest pigment values were registered for T1 (20 degrees C). For phytoremediation, it is necessary to ascertain the relevance and control of the thermal regime of the soil to optimize the phytoextraction of pollutant elements (Cd and Pb).

Cadmium↗
PubMed2003

A coupled fluid-structure finite element model of the aortic valve and root.

BACKGROUND AND AIM OF THE STUDY: The study aim was to develop a three-dimensional coupled fluid-structure finite element model of the aortic valve and root. This model extends previous purely structural finite element models, and represents a significant step toward realistic simulation of the complex interactions among tissue material properties and valvular function. METHODS: The aortic root and valve geometry were extracted from magnetic resonance images and imported into the LS-Dyna explicit finite element package. Leaflet and root tissue were modeled with elastic material properties, and blood was modeled as a Newtonian liquid. A dynamic, fully unsteady analysis was performed in which blood flow through the valve was computed along with the motion of the leaflets and root in response to standard physiologic pressure wave profiles. RESULTS: The opening and closing of the aortic valve under physiological loading conditions was successfully simulated, and feasibility of the model illustrated. The motion of the simulated leaflets was consistent with that seen in intact hearts. Analysis of fluid flow patterns revealed eddy structures in the sinus regions and flow into the coronary circulation. CONCLUSION: The addition of blood flow to structural models of the aortic valve and root is a significant advance in modeling, and allows a closer simulation of valvular function. The model will be used to further assess normal and abnormal physiology as well as the effects of surgical intervention.

Aorta, Thoracic↗