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At least 55 records · Page 3Linked to original sources
PubMed1976

Root fractures in permanent anterior teeth with incomplete root formation.

A follow-up study was made of seven teeth with incomplete root formation observed in a group of 66 permanent teeth with root fracture. Three fractures were overlooked on the initial radiographs, two other teeth were suspected of being fractured, and an accurate diagnosis was made in two cases only. All teeth exhibited markedly increased mobility at the initial examination, and slight dislocation of the coronal fragment was found in two teeth. Following reduction (two teeth) and fixation (all teeth), the observation period ranged from 1 1/2 to 19 years. Retained pulp vitality, repair in the fracture area and, most important, approximately normal root development with closure of the apical foramen were observed in all teeth. Even the occurrence of re-fracture in two semmingly repaired teeth did not jeopardize the long-term result.

Child↗
PubMed2025

Genome-wide identification and analysis of paclobutrazol-resistance gene family in cotton and the positive role of GhPRE3 in salt stress and drought stress resistance.

Compared with other transcription factors, much less studies have been performed on paclobutrazol-resistance (PRE), a subgroup of the extensive bHLH transcription factor gene family, and the research in cotton was also limited. By utilizing the PRE genes and their conserved domains identified in Arabidopsis, a total of 23, 22, 11, and 12 PRE genes were identified from two major cultivated cotton species and their two ancestors, respectively. The cotton PRE gene family was categorized into three subgroups based on evolutionary tree analysis. Motif and intron analyses indicated that the PRE gene has remained highly conserved throughout evolution. Collinearity analysis indicated that gene duplication, particularly through fragment replication, has significantly contributed to the expansion of the cotton PRE family. An exploration of the conserved elements within the PRE gene family uncovered numerous elements associated with plant stress resistance. Additionally, cotton transcriptome and qRT-PCR analysis showed that PRE genes were associated with a variety of abiotic stresses, including salt, drought, and cold treatments. Subcellular localization experiments indicated that the GhPRE3 gene is associated with membrane proteins. Finally, we selected the GhPRE3 gene for a VIGS experiment, which revealed that under salt stress and drought stress conditions, the wilting of leaves in the GhPRE3-silenced plants was significantly more severe than that observed in the control group, with T-AOC levels notably lower and MDA levels significantly higher. Overexpression of GhPRE3 enhanced seed germination and root development in transgenic Arabidopsis thaliana under salt stress and drought stresses. This suggests that GhPRE3 plays a positive regulatory role in cotton tolerance to salt and drought stressed, providing a reference for molecular genetic breeding of cotton with salt and drought tolerance.

Gossypium↗
PubMed1978

A microangiographic study of vascular changes in replanted and autotransplanted teeth of young dogs.

The purpose of the present investigation was to study the revascularization process of the pulp of replanted and autotransplanted teeth with incomplete root development in dogs. A barium-sulfate injection method combined with contact microradiography was used. Ingrowth of apparently new vessels was seen during the first postoperative days. After 10 days, visible vessels were seen in the apical half of the pulp, and after 30 days, in the whole pulp. Branches and apparently also anastomoses between pulpal vessels were seen after 10 days but were especially numerous after 30 days. One hundred eighty days postoperatively, only one of fifteen teeth was devoid of visible vessels, indicating pulpal necrosis. Thirteen of the remaining fourteen teeth exhibited visible vessels throughout the entire length of the pulp. It seems, therefore, that replanted and autotransplanted teeth with open apices have a high potential for repair. The revascularization of the pulp appeared to occur mainly by ingrowth of new vessels. In some instances, however, anastomoses seemed to form to pre-existing vessels in the pulp.

Animals↗
PubMed2026

Establishment of an in vitro culture and regeneration protocol for the native Chilean grass Polypogon australis Brong.

Polypogon australis Brong. is a native Chilean grass frequently found colonizing metal-rich mine tailings, yet it lacks an established in vitro regeneration system to support controlled physiological and biotechnological studies. Here, we report a reproducible protocol for seed germination, callus induction, and plant regeneration using coleoptile-mesocotyl explants. Surface-sterilized seeds were germinated on Murashige and Skoog (MS) medium supplemented with sucrose, achieving a cumulative germination percentage of 47.67 ± 3.15% after 15 days. The coleoptile-mesocotyl explant proved highly responsive to culture on callus induction medium (CIM) supplemented with dicamba, resulting in a callus induction frequency of 30.55 ± 11.96% after 3-5 weeks. Induced calli were predominantly embryogenic, with embryogenic calli representing 65.42 ± 8.61% of the total callus population. Embryogenic calli regenerated complete plantlets with a regeneration efficiency of 45.0 ± 23.3%. Organogenic structures, including primary shoots and roots, developed directly from embryogenic calli maintained on callus induction medium (CIM) supplemented with dicamba, without transfer to a specialized regeneration medium containing organogenesis-promoting growth regulators. After the initiation of organogenesis, cultures were exposed to a 16 h light/8 h dark photoperiod while remaining on CIM, and regenerated plantlets were subsequently transferred to MS+10 S medium for further growth and elongation. This study establishes the first complete in vitro regeneration system for P. australis, providing a practical framework for future physiological studies, large-scale propagation, genetic transformation, and genome engineering applications in this ecologically relevant native Chilean grass.

Regeneration↗
PubMed2016

Characterization of Class III Peroxidases from Switchgrass.

Class III peroxidases (CIIIPRX) catalyze the oxidation of monolignols, generate radicals, and ultimately lead to the formation of lignin. In general, CIIIPRX genes encode a large number of isozymes with ranges of in vitro substrate specificities. In order to elucidate the mode of substrate specificity of these enzymes, we characterized one of the CIIIPRXs (PviPRX9) from switchgrass (Panicum virgatum), a strategic plant for second-generation biofuels. The crystal structure, kinetic experiments, molecular docking, as well as expression patterns of PviPRX9 across multiple tissues and treatments, along with its levels of coexpression with the majority of genes in the monolignol biosynthesis pathway, revealed the function of PviPRX9 in lignification. Significantly, our study suggested that PviPRX9 has the ability to oxidize a broad range of phenylpropanoids with rather similar efficiencies, which reflects its role in the fortification of cell walls during normal growth and root development and in response to insect feeding. Based on the observed interactions of phenylpropanoids in the active site and analysis of kinetics, a catalytic mechanism involving two water molecules and residues histidine-42, arginine-38, and serine-71 was proposed. In addition, proline-138 and gluntamine-140 at the 137P-X-P-X140 motif, leucine-66, proline-67, and asparagine-176 may account for the broad substrate specificity of PviPRX9. Taken together, these observations shed new light on the function and catalysis of PviPRX9 and potentially benefit efforts to improve biomass conservation properties in bioenergy and forage crops.

Amino Acid Sequence↗
PubMed1979

The nutritional significance of root and tuber crop development as staples in the Caribbean community.

The competition between cereals and root crops as CARICOM staples is described. The move to substitute locally grown food for imported wheat is shown to favor root crop development in the region. Against this background, traditional nutrition-prompted objections to wheat substitution by root crops are examined. Evidence is cited to show the essential adequacy of protein in root crops, except plantain and cassava and for all humans except perhaps some infants. The low protein in cassava and plantain, it is proposed, can be easily overcome in the process of local root crop development. Finally, it is argued that there exists the potential to obtain cheap calories from root crops. This and the generation of economic activity among small farmers, concomitant with root crop development, are seen as possible indicators of good nutrition for the region in the future.

Diet↗
PubMed2026

Habitat-Adapted Fungal Symbionts Promote Salt Stress Tolerance Through Distinct Root Mechanisms and Shared Shoot Regulatory Networks in Arabidopsis thaliana.

Salinity is a major constraint to crop productivity. Beneficial plant-fungus interactions represent a promising strategy to enhance stress resilience. Here, we investigated fungal endophytes isolated from the roots of Oryza sativa cultivated in saline-prone marshlands of the Guadalquivir River, Spain. From a collection of 38 isolates, five salt-tolerant strains exhibiting plant growth-promoting activity were identified, including a previously uncharacterized Reticulascus sp. strain S5. Co-cultivation assays with the non-native host plant Arabidopsis thaliana demonstrated that S5 increased the root and shoot biomass under salt stress. To elucidate the underlying molecular mechanisms, a comprehensive RNA-Seq analysis of the roots and shoots under control and saline conditions was performed. Fungal colonization induced pronounced transcriptomic changes, particularly in the shoots, including rewiring of the auxin- and abscisic acid-related pathways and the induction of genes associated with cell wall remodeling. Concurrently, defense-related processes, including glucosinolate biosynthesis and ethylene signaling, were broadly repressed, suggesting attenuated stress perception in colonized plants. In the roots, S5 inoculation suppressed the expression of genes involved in root hair development and cell wall organization, indicating a fungus-driven reconfiguration of root development. Moreover, comparative analysis with Fusarium sp. K-23, a fungus that has previously been demonstrated to promote plant growth under salinity stress, revealed distinct root-associated mechanisms but convergence on a shared regulatory module in shoots involving ABA-responsive transcription factors and osmotic stress regulators. Collectively, our findings demonstrate that Reticulascus sp. S5 enhances plant salt stress tolerance through the coordinated transcriptional reprogramming of growth, hormone signaling, and stress responses, highlighting a possible potential of habitat-adapted endophytes for sustainable crop improvement.

Arabidopsis↗
PubMed1979

Development of the nitrogen-fixing and protein-synthesizing apparatus of bacteroids in pea root nodules.

Some aspects of root nodule development of Pisum sativum inoculated with Rhizobium leguminosarum were examined. 1. Nitrogenase activity (measured as acetylene reduction) appears to be preceded by leghemoglobin synthesis (measured immunologically). 2. Syntheses of component I and component II of nitrogenase are not strictly coordinated. Synthesis of component I starts before component II. 3. Plant and bacteroid protein synthesis (measured by [35S]sulfate labeling) in root nodules declines rapidly during nodule development. Corresponding with this decline is a decrease in quantity and quality of rRNA.

Fabaceae↗
PubMed1978

Studies on hexachlorophene-induced myelin lesions in the trigeminal root transitional region in developing and adult mice.

Hexachlorophene (HCP)-induced intramyelinic vacuolation was studied in the transitional region of the trigeminal root of suckling and adult mice. HCP produced an extensive vacuolation in the central compartment of the region in both suckling and adult mice, while in the peripheral compartment myelin lesions were only seen in mice less than 16 days of age. Gas chromatographic measurements showed that in suckling mice the blood concentration of HCP decreased with age, apparently reflecting a faster elimination of HCP from the blood. By substantially increasing the HCP dose, higher blood concentrations were obtained in adult than less the 16-day-old mice; in spite of this, PNS myelin changes occurred only in the latter. Thus, by observing the HCP effect on the transitional region, where CNS and PNS directly meet, it is concluded that CNS of both suckling and adult mice is more severely effected by HCP than PNS, and that the reaction of the PNS myelin is age-dependent during the period of myelinogenesis; it is particularly vulnerable to a cytotoxic edema inducing substance.

Age Factors↗
PubMed2026

The genome of Thesium ramosoides (Santalales) reveals evolutionary dynamics associated with parasitism and alpine adaptation.

Plant species adapting to complex environments experience contrasting selection pressures that drive the expansion and contraction of different gene families. However, few studies have investigated simultaneous genomic responses to such diverse selective forces. Here, we generate a high-quality genome assembly for the hemiparasitic plant Thesium ramosoides, the first for the largest genus in the Santalales, and explore the genomic basis underlying the evolution of parasitism and alpine adaptation. Unlike many other parasitic plants, the Thesium genome has not undergone additional rounds of whole-genome duplication, making it particularly tractable for studying gene family evolution. Our analyses reveal substantial loss of photosynthesis-related genes and contraction of biotic defense gene families, likely reflecting adaptation to a hemiparasitic lifestyle and reduced pathogen pressure at high altitudes. The absence of key root hair development genes correlates with the degenerate root hair phenotype observed in this species. Furthermore, hallmarks of high-altitude adaptation include the expansion of gene families involved in responses to hypoxia. Notably, expansion of gene families associated with meristem development is consistent with the presence of below-ground crown buds that enable rapid regeneration after mountain fires. Unexpectedly, we detected tandem duplication and diversification of the strigolactone receptor gene D14, which regulates secondary shoot formation, but not of its ancestral paralog KAI2, which mediates seed germination in response to the smoke-derived compound karrikin. This finding suggests divergent signaling mechanisms underlying fire adaptation across different parasitic plant lineages. By integrating time-series transcriptomic data, we propose a post-fire "defense first, repair later, recovery last" model, in which resources are reallocated from immediate defense to rapid repair and ultimately to long-term recovery, to explain the adaptation of T. ramosoides to fire-prone habitats. Our study provides critical insights into the complex and contrasting genomic dynamics that drive adaptation to multiple co-occurring selection pressures.

Genome, Plant↗
PubMed2026

Glucose-TOR Signaling Regulates Root Hair Elongation in Arabidopsis via the RHD6-RSL4 Transcriptional Cascade.

Root hairs are tubular protrusions of root epidermal cells that expand the root surface area to facilitate water and nutrient uptake. The target of rapamycin (TOR) kinase has been identified as a positive regulator of root hair elongation, and the RHD6-RSL4 bHLH transcriptional cascade is well established as a core module that governs root hair morphogenesis. However, whether TOR signaling acts upstream of the RHD6-RSL4 pathway and how glucose signals are integrated into this transcriptional regulatory network during root hair development remain incompletely understood. In this study, transcriptome profiling combined with pharmacological and genetic functional assays was performed to elucidate the TOR-mediated transcriptional regulatory pathway of root hair elongation in Arabidopsis. Chemical inhibition of TOR triggered genome-wide transcriptional reprogramming in seedling roots, including disruption of auxin and ethylene signal transduction and pronounced downregulation of hundreds of genes related to root hair development. Glucose-activated TOR signaling modulates the expression of root hair-specific (RHS) genes mainly through the core RHD6-RSL4 transcriptional cascade. The transcription of RSL1-RSL5 was strongly dependent on functional TOR activity, whereas RHD6 transcript abundance was specifically induced by glucose-TOR signaling under carbon-starvation recovery conditions. Genetic overexpression of either RHD6 or RSL4 partially rescued root hair elongation defects caused by TOR suppression, confirming that the RHD6-RSL4 cascade functions as a critical downstream transcriptional module of glucose-TOR signaling. Collectively, this work establishes a transcriptional framework in which glucose-TOR signals modulate root hair elongation via transcriptional activation of the master bHLH regulators RHD6 and RSL4.

RHD6-RSL4 cascade↗
PubMed1977

The influence of protein-calorie malnutrition on the development of paranodal regions in spinal roots. A study with the OTAN method on rat.

During the early postnatal development of spinal roots in rats paranodal regions were often found, containing OTAN-positive inclusions in the Schwann cell cytoplasm. The presence of OTAN-positive paranodal regions showed variations in time, which were synchronous for ventral and dorsal roots. Dorsal roots, however, showed a more marked presence during development than ventral roots. Spinal roots of animals submitted to a 50% food restriction, were shown to contain more OTAN-positive paranodal regions than controls. This was true for ventral as well as dorsal roots. It is suggested that crowding of internodal segments could be one factor, determining the presence of paranodal, OTAN-positive material.

Animals↗
PubMed1978

Proliferative and degenerative events in the early development of chick dorsal root ganglia. II. Responses to altered peripheral fields.

Responses of chick embryo dorsal root ganglia to early wing bud amputation were examined histologically using tritiated thymidine (3H-TdR) and autoradiography to analyze proliferation and the Feulgen procedure to visualize degenerating cells. Right wing buds were amputated at stage 15 or 16. At 4.5 to 9.5 days of incubation embryos were given a 1-hour exposure to 3H-TdR and fixed. Feulgen-stained autoradiographs were examined for percentage of cells labelled (labelling index) or degenerating (degeneration index) in lateroventral (LV) and mediodorsal (MD) regions of brachial (G14-16) and nonbrachial (G12, 13, 17) ganglia. The earliest response to amputation was a highly significant increase in degeneration indices of LV and MD regions of ipsilateral brachial ganglia at 5.5 days. Significant brachial LV responses were observed throughout the remainder of the experimental period. Two peaks occur in this response: at 5.5 days, corresponding to the peak seen in normal nonbrachial ganglia, and at 8.5 days, having no counterpart in normal development. In brachial MD regions significant degenerative responses occur at most times examined. Significant responses also occur at 7.5 and 8.5 days in MD regions of nonbrachial ganglia. The presence of MD responses in our material indicates that maturation of at least some MD neurons occurs earlier than previously thought. Significant labelling responses occur in brachial LV regions from 7.5 days on. Because other studies (Carr and Simpson, '78a) show that this time is after the end of large-scale neuronal production, this labelling response must be nonneuronal in nature. We conclude that this response is a secondary response to amputation, consequent to the greatly increased cellular degeneration. Results of experiments involving addition of limb buds at the brachial level are also presented.

Amputation, Surgical↗
PubMed1979

Development of mouse dorsal root ganglia: an autoradiographic and quantitative study.

Pulse labelling with tritiated thymidine was used to determine the cell birthdays of dorsal root ganglion (DRG) neurons in foetal mice. The peak number of cell birthdays occurred at 11.5 days foetal age in cervical DRGs, and at 12.5 days in lumbar DRGs. The satellite cells were becoming heavily labelled by day 13.5 in lumbar and some hours earlier in cervical regions. A very sharp peak of satellite cell labelling was seen at 13 days in the lumbar region. Evidence for the existence of more than one neuronal cell type is presented. The earliest cells to stop dividing were part of a widely spread distribution which included all the large neurons. The birthdays of the population of small neurons began later and continued for at least 48 h after division of the large cells had ceased.

Animals↗