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PubMed1992

Effect of root canal infection and treatment of traumatized primary incisors on their permanent successors.

The purpose of the present retrospective study was to evaluate the effect of trauma, root canal infection and treatment of non-vital primary incisors on their permanent successors. A total of 117 permanent central incisors were examined clinically and radiographically for the presence of discolorations, hypoplasia, or disturbances in root development. Of these, 29 were succedaneous to traumatized, endodontically involved and treated primary incisors (Group A). Another 29 had their traumatized, endodontically involved, primary predecessors extracted or left untreated (Group B). The remaining 59 incisors were intact and had no history of trauma (Group C). Severe hypoplasia could not be observed in any of the teeth, and no disturbances in root development could be disclosed radiographically. The incidence of defects in Groups B and C was similar, whereas in Group A it was 2 or 3 times higher than in each of the other two groups. Despite this fact, root canal treatment of traumatized non-vital primary incisors should be considered a treatment option, as premature extraction of a primary incisor may lead to speech problems, premature eruption and/or malalignment of the permanent successor, or affect the child's self image.

Chi-Square Distribution↗
PubMed2026

Identification and functional analysis of MeJA-responsive bHLH family genes in Taraxacum kok-saghyz.

Taraxacum kok-saghyz (T. kok-saghyz) is considered a highly promising alternative source of natural rubber (NR), as its roots synthesize high-molecular-weight NR comparable to that produced by Hevea brasiliensis. The basic helix-loop-helix (bHLH) family of transcription factors (TFs) plays crucial roles in plant organogenesis, hormonal signal transduction, and the regulation of secondary metabolism. This study aimed to systematically identify TkbHLH family members and to elucidate their potential functions in responding to methyl jasmonate (MeJA) and regulating root development. Based on the T. kok-saghyz genome, 172 TkbHLH members were identified and phylogenetically classified into 16 subfamilies. Among these, 37 genes were selected due to their significant induction by MeJA. Sequence analysis confirmed all encoded proteins contain the conserved bHLH domain. Subcellular localization verified nuclear localization of five core TkbHLH proteins. Interactions were shown by yeast two-hybrid and bimolecular fluorescence complementation, revealing these proteins form homodimers and heterodimers. Notably, a specific interaction was detected between TkbHLH162 and TkHMGS1, a key enzyme in the mevalonate (MVA) pathway, suggesting a potential molecular link between JA signaling and the rubber biosynthesis precursor pathway. Functional characterization via overexpression assays showed that selected TkbHLH genes significantly either promoted or inhibited root elongation. In summary, this study presents the first systematic characterization of the bHLH TF family in T. kok-saghyz, elucidating its involvement in JA signal response, protein interaction networks, and root development regulation. These findings provide a crucial foundation for further investigation into the molecular mechanisms by which TkbHLH TFs influence root morphogenesis and NR biosynthesis in T. kok-saghyz.

Taraxacum kok-saghyz (T. kok-saghyz)↗
PubMed1988

Longitudinal study of electrometric sensitivity of young permanent incisors.

Electrometric sensitivity of permanent maxillary central incisors was studied longitudinally in 34 children at 6-month intervals over 2 1/2 yr (mean age of the children at the beginning of the study: 94.6 months). Root development stages were determined from radiographs obtained at the beginning of the study, after 1 yr, and after 2 1/2 yr. An increase in sensitivity was found over the study period, but large variations were found from child to child and even within the same child. Especially at the first examinations a few children showed very low sensitivity. Statistical analysis showed that examination number, root development and side of the mouth (right or left central incisor) all were statistically significantly related to sensitivity. Statistically significant differences were also found between the individuals.

Child↗
PubMed2026

Dual Roles of RAD23b and RAD4 on the Desiccation Tolerance of Germinated Seeds.

Desiccation tolerance (DT) is a survival trait enabling orthodox seeds to withstand extremely low water content. While some protective factors are characterised, it remains mechanistically obscure. Here, based on PEG-induced DT re-establishment in germinated Brassica napus L. seeds, we investigated the dual functions of nucleotide excision repair (NER) components RAD23b and RAD4 in DNA repair and transcriptional regulation of root development. PEG pre-treatment alleviated dehydration-induced DNA damage and activated NER genes, suggesting the involvement of NER in seed DT. Unexpectedly, Arabidopsis atrad23b mutant and BnRAD23b/BnRAD4 over-expressing seeds all exhibited significantly decreased DT after dry back, which evoked a hypothesis that BnRAD23b-BnRAD4 functions beyond NER. Normally, BnRAD4 interacted with BnRAD23b and repressed the expression of root development genes NAC103, EMB1444, RRA1 by directly binding to STRE elements within their promoters. Dehydration stress alleviated this repression, drove transcriptional reprogramming and might redirect the complex to execute DNA repair. Genetic analyses revealed that germinated seeds of atnac103, atemb1444, and atrra1 single mutants all exhibited reduced DT, and double mutants under atrad23b background almost abolished DT. This study suggests that RAD23b and RAD4 may regulate DT re-establishment of germinated seeds through balancing genome integrity and radicle development, with implications for DT study broadly.

Brassica napus L.↗
PubMed1988

Glutamate synthase in Medicago sativa L. Occurrence and properties of FD-dependent enzyme in plant cell fraction during root nodule development.

In the plant cell fraction of Medicago sativa (L. cv Europe) nodules, glutamate synthase is active with reduced Fd, MV, NADH and NADPH as an electron donor. Up to 25 to 30 days after inoculation, the activities of Fd-dependent glutamate synthase (EC 1.4.1.7), the most active form of the enzyme, NADH-dependent (EC 1.4.1.14) and NADPH-dependent (EC 1.4.1.13) glutamate synthases increase about 2-fold followed by a relatively constant level per gram fresh weight of nodules. The activities of glutamate synthases with different electron carriers increase constantly about 30-fold after 46 days of inoculation by total fresh weight of nodules per plant. These nodule glutamate synthase activities with Fd, NADH or NADPH represent 30% relative to those of root glutamate synthases per plant with the respective electron donor. Fd-glutamate synthase in nodule plant fraction is a protein molecule immunochemically distinct from pyridine nucleotide-glutamate synthases. MV-linked enzyme activity is associated with Fd-glutamate synthase. The Fd-glutamate synthase has a subunit molecular mass of 68.2 kDa, and it exhibits a high affinity for spinach Fd as an electron carrier. The increase in Fd-glutamate synthase activity during nodule development is accompanied by a rise in the enzyme protein content. The total activity of different forms of glutamate synthase in vitro ensures a higher level than the rate of ammonia production during N2 fixation in bacteroids of Medicago sativa nodules.

Blotting, Western↗
PubMed1978

[Induction of jaw bone formation by tooth autotransplantation].

A case-report of segmental underdevelopment of the alveolar process in the upper jaw of an eleven-year old girl is presented. At the site where the alveolar ridge was underdeveloped, two impacted malformed incisors were found. The malformed teeth had almost normal crowns, but the root-development had terminated 1-2 mm beyond the cementoenamel junction. The patient was treated by removal of the two malformed impacted teeth, followed by autotransplantation of the developing second premolar with the intention of inducing bone formation. The result was promising. After 3 years the alveolar process had developed to almost normal vertical hight. Some considerations are made regarding the possible origin of the bone induction factors in tooth buds. The fact that this patient demonstrated an underdevelopment of the alveolar process in spite of the formation of almost normal crowns, is taken as evidence that the bone stimulating principle in tooth buds are not to be found in the enamel organ proper, but must be related to Hertwig's epithelial sheath, root development and tooth eruption.

Alveolar Process↗
PubMed2026

Genome-Wide Analysis of Triticum aestivum Root Meristem Growth Factor (RGF) Gene Family Highlights TaRGF5 as a Putative Component of Root-Associated Signaling.

Wheat (Triticum aestivum), a key global crop, faces rising drought stress that limits root growth and water uptake. Root meristem growth factors (RGFs) are small peptides that regulate root stem cell maintenance, meristem activity, and lateral root formation in model plants, yet the RGF gene family remains unexplored in wheat. Here, we performed a comprehensive genome-wide analysis of the TaRGF gene family, identifying 15 genes distributed across the A, B, and D subgenomes and classified into five homeologous groups (TaRGF1-TaRGF5), predominantly located on chromosomes 2 and 6. All TaRGFs contained a characteristic RGF motif, with dibasic cleavage sites and Asp-Tyr motifs indicating conserved maturation mechanisms. Based on the phylogenetic analysis, the TaRGF5 homeologs showed the highest similarity to Arabidopsis thaliana RGF5. Tested RNA-seq data revealed predominantly root-enriched expression for all TaRGF genes, with TaRGF5 exhibiting the most root-preferential and downregulation under drought stress. Quantitative real-time PCR (qRT-PCR) confirmed that drought stress suppressed the expression of TaRGF5A, TaRGF5B, and TaRGF5D in roots of wheat cultivar Sids-13 across all time points, unlike the higher accumulation seen in controls. Promoter analysis predicted a unique BES1 transcription factor binding site exclusively in TaRGF5B, linking brassinosteroid signaling to peptide-mediated root regulation. Structural modeling and molecular docking predicted an interaction between wheat TaRGF5 homeologs and root growth factor-insensitive receptor kinase (TaRGI3), characterized by conserved sulfotyrosine-mediated binding and favorable interaction energetics. Based on this characterization of the wheat RGF gene family, particularly the potential role of TaRGF5 in root development and drought-adaptation signaling, we propose targeting this gene for functional analysis to improve wheat resilience under water-limited conditions.

Triticum↗
PubMed1988

Improvement of dental development in osteopetrotic mice by maternal vitamin D3 sulfate administration.

Utilizing the microphthalamic mouse, (mi/mi) as a model of osteopetrosis, vitamin D3 (cholecalciferol) was administered prenatally and postnatally to study its effects on tooth development and subsequent eruption. It has previously been reported that vitamin D3 crosses the placental barrier and is absorbed into mammary gland milk. Fifteen heterozygotes (+/mi) were used as breeders. There were three study groups: A) 5.0 ng/gm cholecalciferol sulfate; B) 2.5 ng/gm cholecalciferol sulfate; and C) no therapy. Intraperitoneal injections were administered three times per week, beginning when pregnancy was evident, and continuing for 4 additional weeks during lactation. Approximately half of the 59 offspring were sacrificed at age 1 day and the other half at 4 weeks. The former group was studied for crown development, and the latter group was studied for root development and eruption. When the osteopetrotic offspring of group A were compared with osteopetrotic offspring of group C, crown development and tooth eruption were substantially more advanced. Parameters examined were maturity of the ameloblasts and odontoblasts, dentin and enamel formation, root sheath development, status of eruption, and degree of apex closure. It was concluded that cholecalciferol sulfate significantly improves tooth development and subsequent eruption in the osteopetrotic mouse. A genetic disease has had its phenotype modified by vitamin therapy during gestation.

Animals↗
PubMed1987

Development of the spinal nerves in the lamprey: III. Spinal ganglia and dorsal roots in 26-day (13 mm) larvae.

Serial sections of the trunk and tail of 26-day (13 mm) larval lampreys were examined by light and electron microscopy. Trunk region: Spinal ganglia and ventral nerves are seen alternately along the spinal cord and the notochord in the trunk. Spinal ganglia are located medially in intermyotome spaces with intersegmental blood vessels and send "dorsal nerves" ventrally along the vessels. "Ventral nerves" are seen on the midmedial surface of each myotome. Fibers containing dense-cored vesicles occur in the dorsal root but not in the ventral root. Caudal region: In the caudal one-third of the tail the ventral nerves are formed earlier than spinal ganglia and dorsal nerves. The most caudal (primitive) ventral nerve (root) develops at the 12th myotome from the caudal end of the series of myotomes, the caudalmost ganglion being formed between the 15th and the 14th myotome in a 13-mm larval lamprey. The intimate association of dorsolateral outflow (DLO) fibers (Nakao and Ishizawa: J. Comp. Neurol. 256:356-368, '87b) with neural crest cells (DO cells of Nakao and Ishizawa; ibid.) strongly suggested that these fibers play an important role as the substrate for guiding the cells to form compact cell masses as primitive spinal ganglia. Two types of cell groups are progressively distinguished in primitive spinal ganglia during development. One of them has a light round nucleus with a prominent nucleolus and a large amount of the perinuclear cytoplasm that contains abundant free ribosomes, rough endoplasmic reticulum (ER), numerous Golgi apparatuses, and dense bodies. Cells of the other type are characterized by a dense, flattened nucleus with a small amount of perinuclear cytoplasm that extends as a thin cytoplasmic sheet to surround cells of the other type as a whole, the basal lamina surrounding the whole cell mass. The former type is interpreted as neural cells and the latter satellite cells of the ganglion. Central processes of ganglionic neural cells are assumed to enter the spinal cord along DLO fibers by using them as a substrate to establish the dorsal root. Intersegmental blood vessels develop later than spinal ganglia and peripheral processes extend along the vessels.

Animals↗
PubMed1987

In vivo effect of brain-derived neurotrophic factor on the survival of developing dorsal root ganglion cells.

Implantation of silastic membranes between neural tube and somites at somitic levels 20-24 in 30-somite-stage chick embryos results in separation of early migrated neural crest cells of the dorsal root ganglion (DRG) anlage from the neural tube and their death within a few hours [Kalcheim and Le Douarin, (1986) Dev. Biol., 116, 451-460]. The in vivo effects of brain-derived neutrotrophic factor (BNDF) on survival of HNK-1 immunoreactive DRG cells separated from the tube were examined by implantation of laminin-treated silastic membranes (controls) or BDNF/laminin-treated membranes. In the presence of BDNF/laminin-treated membranes, 20/25 grafted embryos fixed 10 h after implantation, contained many rescued cells on the operated side. In contrast, only a few rescued cells on the operated side. In contrast, only a few rescued cells were observed in sections on the operated in 2/11 embryos implanted with laminin-treated silastic membranes, and no rescued cells at all could be detected in embryos implanted with NGF/laminin-treated (seven embryos) or untreated silastic membranes (12 embryos). The data presented support the hypothesis that early survival and differentiation of neural crest-derived sensory cells depend on central nervous system-derived factor(s). Moreover, this is the first evidence for the in vivo activity of BDNF on survival of developing DRG cells.

Animals↗
PubMed1987

Effects of Rhizobium meliloti nif and fix mutants on alfalfa root nodule development.

Ineffective alfalfa nodules were examined at the light and electron microscope level after inoculation with Rhizobium meliloti strains with mutations in nif and fix genes. All the mutant strains induced nodules that contained elongated bacteroids within the host cells, but the bacteroids quickly senesced. The nodules were small and numerous, and the host cells also exhibited symptoms of an ineffective symbiosis. nifB, fixA, and fixB bacteroids appeared to be completely differentiated (by ultrastructural criteria), i.e., as bacteroids developed, they increased in diameter and length and their cytoplasm underwent a change from homogeneous and electron dense to heterogeneous and electron transparent after enlargement. In contrast, nifA bacteroids rarely matured to this state. The bacteroids degenerated at an earlier stage of development and did not become electron transparent.

Medicago sativa↗
PubMed1987

Lupin leghemoglobins during root nodule development.

Two yellow lupin leghemoglobins, Lb I and Lb II, were purified to homogeneity using the HPLC technique for final separation. Lb I and Lb II were identified by the N-terminal sequences and their reaction with antibodies against electrophoretically pure leghemoglobin. The third Lb species was detected by the combined method of isoelectrofocusing and PAGE of Lb I. It seems that Lb III represents a posttranslational modification of Lb I. Developmental changes in Lb multiple forms were examined using the Western blotting method. The content of leghemoglobin, first detectable approximately 3 weeks after infection, increased up to 6-7 weeks, and then it remained at the same level until 8-9 weeks after the infection. At the early stages of nodule formation Lb I prevailed over Lb II, while later Lb II became the predominant form. This suggests physiological role of particular forms and precise regulation of the expression of Lb genes.

Amino Acid Sequence↗
PubMed1990

A long-term study of 370 autotransplanted premolars. Part III. Periodontal healing subsequent to transplantation.

The purpose of the present investigation was to determine the long-term prognosis of autotransplanted premolars with respect to periodontal healing. The subjects consisted of 195 patients aged 7 to 35 years, with a total of 370 autotransplanted all operated and followed with a standard technique. The observation period ranged from 1 to 13 years. Periodontal healing as demonstrated radiographically was complete in most cases after 8 weeks. Root resorption occurring after transplantation was divided into surface-, inflammatory- and replacement resorption (ankylosis). Root resorption occurred in 52 of the transplanted teeth and was usually diagnosed within 6 months. Root resorption was found to be significantly related to increasing stage of root development and the stage of eruption at the time of transplantation. Subsequent orthodontic movement of teeth with completed root formation at the time of transplantation resulted in a slight increase in the frequency of both surface and inflammatory resorption. The present study indicates that trauma to the PDL of the transplant is the explanatory factor for the development of root resorption.

Adolescent↗
PubMed1990

[Tooth movement of an impacted lower 2nd premolar in the root developmental stage--a follow-up radiographic observation on the root formation].

A 9 year old girl presented an impacted lower right 2nd premolar which not only was in horizontal position, but its crown was directed lingually. As a lower right 2nd premolar was in such a position that normal eruption was impossible, the deciduous predecessor was extracted at 9 years of age, and then sufficient space had been created for the lower right 2nd premolar to be erupted, and the eruption of it was observed for about 2 years. 2 years later, radiographic indication showed that no spontaneous eruption of a lower right 2nd premolar was to be expected. At 11 years of age, surgical exposure and traction of a lower right 2nd premolar was attempted. When the lower right 2nd premolar was upright, its root formation was in the 1st stage of root developmental stages according to Moorrees et al. Follow up radiographic observations on surgical exposure and traction of a lower right 2nd premolar 3 years later revealed the following results: 1. The root development went on to amount to about 90 percent of the root formation of the other tooth concerned without the curvature of the root. 2. Lamina dura and periodontal space were normal. The continued root formation was narrowing the root apex and the pulpal tissue of apical foramina was continuous with the periodontal space surrounding the root. 3. Bone deposition occurred at the alveolar crest and the latter was recontoured normally. The interdental and inter-radicular trabecula were good. As based on these results, normal development of the root of a lower right 2nd premolar with normal periodontium can be anticipated. Clinically, the lower right 2nd premolar had completely erupted and was in normal position on the arch and in occlusion. Color, vitality and mobility were normal. Periodontal support was good. The above-mentioned findings give support to the possibility that "early treatment" enables the impacted tooth to correct.

Bicuspid↗