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At least 73 records · Page 4Linked to original sources
PubMed2026

Penicillium melinii promotes root growth through subtle host reprogramming across model and crop species.

Root development is highly responsive to microbial interactions, yet the mechanisms by which beneficial fungi promote root growth remain incompletely understood. Here, we identified Penicillium melinii 'isolate 2' through a screen of endophytic fungi isolated from Arabidopsis and characterized it as a promoter of root development in both Arabidopsis and crop species. We combined phenotyping in vitro, rhizotron, greenhouse and field assays with reporter and mutant analyses, transcriptomics, phytohormone profiling and sequencing and annotation of the fungal genome to investigate the basis of this interaction. P. melinii consistently stimulated root growth and modified root architecture across experimental systems and host species. These effects were associated with subtle but reproducible host transcriptional reprogramming, supporting a model in which the fungus fine-tunes endogenous developmental programmes rather than broadly perturbing stress or growth pathways. Genetic and reporter analyses further suggested that this interaction modulates root branching through localized developmental reprogramming. Genomic analysis provided a framework for understanding the fungal traits associated with this beneficial interaction. The conservation of the response across model and crop species supports the relevance of P. melinii as both a useful experimental system to study beneficial plant-fungus interactions and a promising candidate for improving root traits and crop performance.

Penicillium melinii↗
PubMed1990

Toxicity of root canal sealers on rat bone cells in primary culture.

The cytotoxic effects on cultured rat bone cells of newly-developed root canal sealers and commercially available sealers were compared. Various root canal sealers were applied to cultured bone cells obtained from rat calvaria by the enzyme digestion method. Measurement of [3H]-thymidine incorporation, alkaline phosphatase activity, and calcium release were performed after 24 and 48 h. No significant difference was found in cellular DNA synthesis and alkaline phosphatase activity between cells exposed to New B-1, New B-5 and controls after exposure for 24 and 48 h. Cells in contact with Tubliseal, Diaket and AH-26 demonstrated a significant difference from controls in DNA synthesis and alkaline phosphatase activity. Calcium release at 24 h was significantly different in the cells treated with New B-1 and New B-5 than in controls. No appreciable difference was found, however, between New B-6, Sealapex and controls. At 48 h, cells treated with New B-1, New B-5 and New B-6 showed differed significantly difference from controls, but the cells exposed to Sealapex did not. The newly-developed root canal sealers had lower toxicity in vitro than five types of commercially available root canal sealers.

Alkaline Phosphatase↗
PubMedDate not supplied

The relationship between nodulin gene expression and the Rhizobium nod genes in Vicia sativa root nodule development.

The role of the Rhizobium nod genes in the induction of nodulin gene expression was examined by analyzing nodules formed on vetch roots by bacterial strains containing only the nod region. Introduction of an 11-kb cloned nod region of the R. leguminosarum sym plasmid pRL1JI into sym plasmid-cured rhizobia conferred on the recipient strains the ability to induce nodules in which all nodulin genes were expressed. This proves that from the sym plasmid only the nod region is involved in the induction of nodulin gene expression. A transconjugant of Agrobacterium carrying the same nod region induces nodules in which only early nodulin gene expression is detected. Thus, the nod region is essential for the induction of early nodulin gene expression. In this case, nodule cytology may indicate that a defense response of the plant interferes with the induction of late nodulin gene expression. Indirect evidence is presented that indeed the Rhizobium nod genes are also in some way involved in the induction of the expression of late noduling genes. The combination between histological data and pattern of nodulin gene expression furthermore reveals a correlation between nodule structure and nodulin gene expression. This correlation may aid in speculations about the functions of nodulins.

Blotting, Western↗
PubMed1989

Prognosis of root-fractured permanent incisors--prediction of healing modalities.

A population of 85 patients, comprising 95 root-fractured permanent incisors followed up to 11 years, was studied prospectively for the type of fracture healing that occurred (i.e. union of the fragments by interposition of hard tissue (HT) or connective tissue (CT), or nonunion characterized by interposition of granulation tissue between the fragments (GT)). Initial treatment was provided according to established treatment guidelines by the attending oral surgeon at the emergency room. Follow-up examination and treatment were provided by 2 of the authors. It appeared that GT could be diagnosed after approximately 3 weeks, while HT or CT could be diagnosed approximately 6 weeks after trauma. Many factors considered one at a time were found to have a significant or nearly significant effect on the type of fracture healing that occurred. However, a multivariate regression analysis revealed that the following factors were significantly related to fracture healing by HT: a large diameter of the apical foramen and severity of luxation of the coronal fragment (concussion/subluxation greater than lateral luxation greater than extrusion); fracture healing by CT: the presence of restorations in the injured teeth at the time of injury and the presence of marginal periodontal disease; and fracture nonhealing by GT: type of fixation (i.e. orthodontic band fixation versus acid etch or no fixation), antibiotic therapy, a constricted apical foramen, increased loosening of the coronal fragment, and stage of root development (GT never occurred in teeth with open apices). It was previously demonstrated following luxation injuries that type of luxation, stage of root development and type of fixation (orthodontic bands versus acid etch or no fixation) determined the prognosis of pulp survival. It therefore appears that the general factors that are able to predict the type of healing seen after root fracture are the same as those after luxation injuries, supporting the hypothesis that root fractures are another form of luxation injury, this time of only the coronal fragment.

Humans↗
PubMed1978

Proliferative and degenerative events in the early development of chick dorsal root ganglia. I. Normal development.

Development of the chick dorsal root ganglia was examined in 4.5- to 9.5-day embryos. Tritiated thymidine (3H-TdR) and autoradiography was used to analyze proliferative activity and the Feulgen procedure to analyze degenerative activity in ganglia 12-17. Proliferative activity was found to be elevated through 4.5 days of incubation when as many as 14% of the ganglionic cells become labelled following a one-hour exposure to 3H-TdR. By 6.5 to 7.5 days proliferative activity decreases to 2-4% in the lateroventral (LV) regions and to approximately 1% in the mediodorsal (MD) regions of the ganglia. However, there appears to be increased proliferative activity by the end of the experimental period at 9.5 days. Birthdate studies demonstrate that large-scale neuronal production occurs between 4.5 and 6.5 days in the LV regions and between 4.5 and 7.5 days in the MD regions. After those times ganglionic proliferative activity must be largely nonneuronal in nature. This nonneuronal proliferation is greater in LV than in MD regions and in brachial than in nonbrachial ganglia. Degenerative activiy was found to be absent from the ganglia until after 4.5 days of incubation. It then increases rapidly, and by 5.5 days 5% of the LV cells in nonbrachial ganglia are degenerating. Degenerative activity then declines but is still present at 9.5 days. In contrast to results of an earlier study (Hamburger and Levi-Montalcini, '49), degenerative activity was also found in the LV region of brachial ganglia and the MD regions of brachial and nonbrachial ganglia. The pattern of LV degenerative activity in brachial ganglia is similar to that in nonbrachial ganglia, but the level of activity is lower. In the MD regions degenerative activity increases throughout the experimental period, and by 9.5 days as many as 4% of the MD cells are degenerating.

Age Factors↗
PubMed1976

Radiographic and clinical manifestations of the impacted mandibular third molar.

Observations were made on 200 impacted mandibular third molars that were removed from 200 unselected patients under local anesthesia. Sixty percent of the teeth were found to be in apparent relationship with the inferior dental canal: 19 % in true relationship and 41 % in superimposition. The vertical impacted molars were mainly found to be in true relationship with the inferior dental canal. On comparison of the clinical postoperative diagnosis with the radiographic preoperative findings an error of only 0.8 % was shown. Most of the molars showed fully developed roots in the third decade of life. Most of the teeth in this series were vertically impacted having mostly fully developed roots. There was a significant correlation between the patients suffering from pain, trismus, and swelling. Swelling and trismus were the mostly affected postoperative sequelae.

Adolescent↗
PubMed1988

Autogenous free tooth transplantation in man by a 2-stage operation technique. A longitudinal intra-individual radiographic assessment.

Insufficient nutrition to the root surface of autotransplanted mature human teeth after transplantation could be an explanation for the high rates of complications such as root resorption and loss of the tooth transplant. Insufficient nutrition is suggested as being due to the distance between the recipient site tissue and the root surface, and the presence of a blood-clot between the tissues. Improved nutrition could be achieved by transplanting into contact with the vascularised connective tissue of a healing wound. To test this hypothesis, a series of human teeth with fully developed roots were autotransplanted to recipient sites prepared and left to heal for 14 days before transplantation. This study is a follow-up of 57 transplants with a minimum observation time of 1 year. Periodic radiographic examinations of the teeth were performed up to 5 years after transplantation. The results presented, showed a lower incidence of root resorption and extractions than previously reported for teeth with fully developed roots.

Adolescent↗
PubMed1989

[Study of trace elements in bovine permanent teeth germ].

It is well documented that uptake of various trace elements take place during tooth development. The purpose of this experiment was to analyze the uptake amount of these various trace elements, in particular Cd, Zn, Pb and Cu throughout the tooth germ formation all the way up to the eruption stage. Bovine permanent tooth germs were used in this experiment. Instead of the conventional morphologic stages, further subdivision into eight groups were employed. The resultant findings were as follows: 1) Uptake of Cd and Zn were verified during the root development to early tooth eruption stage in enamel. Meanwhile, for dentin, the uptake was corroborated from the root development to the late tooth eruption stage. 2) Uptake of Cu was verified during the late tooth eruption stage in enamel. However, no uptake occurred in dentin in any of the various stages. 3) Uptake of Pb occurred during the late tooth eruption stage in enamel. Meanwhile, in dentin, constant equivalent amount of uptake was seen throughout all of the stages. 4) Quantitative analysis of the Cd, Zn and Pb uptake in both enamel and dentin clearly indicated that enamel showed much higher values. The uptake of Cu was found to be significantly high in the groups of the coronal one-third and the eruption four-fifth groups for enamel. Meanwhile, the crown completion group to the half erupted group showed significantly high values for dentin. Based on the above findings, one can deduce clear correlation between enamel organ development and the uptake of the said various trace elements.

Animals↗
PubMed1991

Synchronous expression of leghaemoglobin genes in Medicago truncatula during nitrogen-fixing root nodule development and response to exogenously supplied nitrate.

Two leghaemoglobin genes from the diploid, autogamous Medicago truncatula (Mtlb1 and Mtlb2) have been cloned and their nucleotide sequences determined. The deduced amino acid sequences encoded by these two genes differ significantly (18%), confirming that they belong to different sub-groups of Medicago leghaemoglobin genes. RNAse protection experiments have been used to show that both genes are transcriptionally active, and are expressed specifically in the nitrogen-fixing root nodule of M. truncatula. Whilst Mtlb1 mRNA is present at approximatively 3-fold higher steady-state levels than Mtlb2 mRNA, the transcription of both genes is triggered concomitantly during nodule development (5 days after inoculation with Rhizobium meliloti), and the ratio of the steady-state levels of the two mRNA species remains constant throughout nodule maturation. When the growth medium of nodulated M. truncatula is supplemented with 5 mM KNO3 over a period of 2-3 days there is a progressive drop in specific nitrogen fixation activity to only 20-25% of the original level. This is accompanied with a parallel and synchronous reduction in the quantities of mRNA corresponding to both Mtlb1 and Mtlb2. By contrast, the expression of the nodule parenchyma-specific gene ENOD2 is not significantly modified following nitrate treatment, clearly demonstrating differences in tissue-specific gene regulation in response to combined nitrogen.

Amino Acid Sequence↗
PubMed1990

Expression of attachment proteins during cementogenesis.

There is general agreement that during development the extracellular environment plays a critical role in controlling cell differentiation. Data generated from numerous studies support the possibility that cell attachment proteins and their corresponding cell receptors are possible candidates for this role. In particular, our studies are directed at identifying attachment proteins in mature cementum and establishing the function of these proteins during root formation. Fractionation of guanidine HCL/EDTA extracts of cementum revealed the presence of a bone-associated attachment, BSP, as well as fractions containing as of yet undetermined attachment proteins. Immunofluorescent examination of 1st molar tissues during root formation, obtained from 7 day-old mice neonates, for bone-associated attachment proteins indicated that osteopontin is expressed in the area of Hertwig's epithelial root sheath, but not in the region of the dental papillae. However, dental papillae cells, considered to have the capacity to form cementum, attached to osteopontin coated dishes, in vitro. Thus, unique attachment proteins, as well as those previously identified, were found in mature cementum and during root development. Future studies focused on identifying attachment proteins of mature cementum and determining the spatial and temporal localization of these proteins, pre- and post-cementogenesis, will provide important information necessary for establishing the function of these proteins during root development.

Animals↗
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↗