The peptide GOLVEN10 alters root development and noduletaxis in Medicago truncatula.

The conservation of GOLVEN (GLV)/ROOT MERISTEM GROWTH FACTOR (RGF) peptide encoding genes across plant genomes capable of forming roots or root-like structures underscores their potential significance in the terrestrial adaptation of plants. This study investigates the function and role of GOLVEN peptide-coding genes in Medicago truncatula. Five out of fifteen GLV/RGF genes were notably upregulated during nodule organogenesis and were differentially responsive to nitrogen deficiency and auxin treatment. Specifically, the expression of MtGLV9 and MtGLV10 at nodule initiation sites was contingent upon the NODULE INCEPTION transcription factor. Overexpression of these five nodule-induced GLV genes in hairy roots of M. truncatula and application of their synthetic peptide analogues led to a decrease in nodule count by 25-50%. Uniquely, the GOLVEN10 peptide altered the positioning of the first formed lateral root and nodule on the primary root axis, an observation we term 'noduletaxis'; this decreased the length of the lateral organ formation zone on roots. Histological section of roots treated with synthetic GOLVEN10 peptide revealed an increased cell number within the root cortical cell layers without a corresponding increase in cell length, leading to an elongation of the root likely introducing a spatiotemporal delay in organ formation. At the transcription level, the GOLVEN10 peptide suppressed expression of microtubule-related genes and exerted its effects by changing expression of a large subset of Auxin responsive genes. These findings advance our understanding of the molecular mechanisms by which GOLVEN peptides modulate root morphology, nodule ontogeny, and interactions with key transcriptional pathways.

Gene editing to improve legume-rhizobia symbiosis in a changing climate.

In the last three years, several gene editing techniques have been developed for both model and crop legumes. CRISPR-Cas9-based tools, in particular, are outpacing other comparable gene editing technologies used in legume hosts and their microbial symbionts to understand the molecular basis of symbiotic nitrogen-fixation. Gene editing has helped identify new gene functions, validate genetic screens, resolve gene redundancy, examine the role of tandemly duplicated genes, and investigate symbiotic signaling networks in non-model plants. In this review, we discuss the advances made in understanding the legume-rhizobia symbiosis through the use of gene editing and highlight studies conducted under varying environmental conditions. We reason that future climate-hardy legumes must be able to better integrate environmental signals with nitrogen fixation by fine-tuning long distance signaling, continuing to select efficient rhizobial partners, and adjusting their molecular circuitry to function optimally under variable light and nutrient availability and rising atmospheric carbon dioxide.

Running a research group in the next generation: combining sustainable and reproducible research with values-driven leadership.

In the summer of 2021, we held a community workshop at the International Congress of Arabidopsis Research (ICAR) aimed at early career researchers and focused on values-based lab leadership. Here, we elaborate on ideas emerging from the workshop that we hope will allow current and future group leaders to reflect on and adjust to the rapidly evolving nature of the academic scientific enterprise.

A rulebook for peptide control of legume-microbe endosymbioses.

Plants engage in mutually beneficial relationships with microbes, such as arbuscular mycorrhizal fungi or nitrogen-fixing rhizobia, for optimized nutrient acquisition. In return, the microbial symbionts receive photosynthetic carbon from the plant. Both symbioses are regulated by the plant nutrient status, indicating the existence of signaling pathways that allow the host to fine-tune its interactions with the beneficial microbes depending on its nutrient requirements. Peptide hormones coordinate a plethora of developmental and physiological processes and, recently, various peptide families have gained special attention as systemic and local regulators of plant-microbe interactions and nutrient homeostasis. In this review, we identify five 'rules' or guiding principles that govern peptide function during symbiotic plant-microbe interactions, and highlight possible points of integration with nutrient acquisition pathways.

Comparative evaluation of postoperative pain and tissue response in patients undergoing conventional flap surgeries with or without 940 nm diode laser exposure - A randomized clinical study.

BACKGROUND: Over the past few years, a growing body of evidence has allowed us to ascertain that the initiation of periodontitis stems from the existence of oral microbial biofilm and that this requires definitive treatment. Owing to its exceptional usability, affordability, and antibacterial activity, the "diode laser" (DL) has increasingly become a popular and important tool in a dentist's armamentarium. However, there is a scarcity of scientific evidence on the utility and advantages of using "diode laser" in periodontal flap surgery. The study aimed to determine the efficacy of 940 nm diode laser exposure in combination with conventional periodontal flap surgery for the treatment of chronic periodontitis to evaluate postoperative discomfort and clinical parameters. MATERIALS AND METHODS: A total of 10 subjects (7 males and 3 females) with generalized chronic periodontitis were recruited and completed the study without any dropouts. For this split-mouth study, 40 sample sites with pocket probing depth (PPD) 5-7 mm post periodontal Phase I therapy were selected. The quadrants were randomly allocated to Groups A, B, C, and D using the fish bowl lottery method. Kirkland flap surgery with laser and modified Widman flap (MWF) with laser were performed in Group A and C, respectively, while Kirkland flap surgery and MWF surgery were performed in Group B and Group D. Clinical parameters including visual analog scale (VAS) score and gingival inflammation were determined at 3rd and 7th day postoperatively while PPD, clinical attachment level (CAL), and sulcus bleeding index (SBI) were recorded at baseline and 6 months following treatment. Wilcoxon signed-rank test and Kruskal-Wallis test were used for intra-group and inter-group comparison of parameters, respectively. RESULTS: Statistically significant difference was attained with postoperative discomfort in laser-assisted groups on 1st and 3rd day postoperatively (P < 0.001). There was no significant difference in the proportion of subjects with gingival inflammation. A statistically significant reduction in mean PPD at 6 months postoperatively was seen among all study groups (P < 0.05) but the inter-group difference was not statistically significant. SBI score reduced significantly from baseline to 6 months follow-up among all four groups (P < 0.05). However, we did not find the inter-group difference to be statistically non-significant. CONCLUSION: Diode laser as an adjunct to the surgical procedure can demonstrate appreciable benefits by increasing the CAL and minimizing the postoperative pain and the probing pocket, but such additional effects were not observed with gingival inflammation.

MtNPF6.5 mediates chloride uptake and nitrate preference in Medicago roots.

The preference for nitrate over chloride through regulation of transporters is a fundamental feature of plant ion homeostasis. We show that Medicago truncatula MtNPF6.5, an ortholog of Arabidopsis thaliana AtNPF6.3/NRT1.1, can mediate nitrate and chloride uptake in Xenopus oocytes but is chloride selective and that its close homologue, MtNPF6.7, can transport nitrate and chloride but is nitrate selective. The MtNPF6.5 mutant showed greatly reduced chloride content relative to wild type, and MtNPF6.5 expression was repressed by high chloride, indicating a primary role for MtNPF6.5 in root chloride uptake. MtNPF6.5 and MtNPF6.7 were repressed and induced by nitrate, respectively, and these responses required the transcription factor MtNLP1. Moreover, loss of MtNLP1 prevented the rapid switch from chloride to nitrate as the main anion in nitrate-starved plants after nitrate provision, providing insight into the underlying mechanism for nitrate preference. Sequence analysis revealed three sub-types of AtNPF6.3 orthologs based on their predicted substrate-binding residues: A (chloride selective), B (nitrate selective), and C (legume specific). The absence of B-type AtNPF6.3 homologues in early diverged plant lineages suggests that they evolved from a chloride-selective MtNPF6.5-like protein.

Role of Selective Serotonin Reuptake Inhibitors in Prognosis Dental Implants: A Retrospective Study.

BACKGROUND: Many recent research shows that antidepressants interfere with the osseointegration of implants. The main purpose of this study was to determine the association between selective serotonin reuptake inhibitors (SSRI) and dental implant failure. MATERIALS AND METHODOLOGY: A retrospective study consisted of 410 patients (720 dental implants). Patients' records were used to retrieve the history of SSRI use and medication. The study consists of two groups. Group I (SSRI users) consisted of 128 patients (245 dental implants) patients, whereas Group II (non-SSRI users) was formed by 282 patients (475 dental implants). The implant failure rate was evaluated and statistically examined using the Chi-square test. RESULTS: Group I had 30 implant failures with 13 (12%) males and 14 (11.8%) females, whereas Group II had 28 implant failures with 12 (6.3%) males and 16 (5.6%) females. In Group I, 26% of the implants failed in the age group >50 years, whereas it was 10.4% in Group II. However, in the age group <50 years, it was 6% and 4.2% Groups I and II, respectively. Group I shows that out of 40 implants in diabetic patients, 12 had failure, whereas in Group II, out of 32 implants placed in diabetics, 7 had failure. In smokers, 48% of the implants failed in Group I, and 29% in group II. In non-smokers the failure was seen in 7.7% cases in Group I and 2.1% cases in Group II. The difference was statistically significant (P < 0.05). CONCLUSION: The usage of SSRIs is associated with an increased rate of implant failure. It has a deleterious effect on bone remodeling and leads to excessive osteoporosis.

Evaluation of Healing of Periapical Tissue in Permanent Incisors with Open Apices after Unintentional Extrusion of Mineral Trioxide Aggregate - A Retrospective Study.

AIM: The aim of the present study was to retrospectively assess the healing of periapical lesions in permanent central incisors with open apices after unintentional extrusion of mineral trioxide aggregate (MTA). MATERIALS AND METHODS: The clinical and radiographic records of 75 maxillary permanent central teeth treated by MTA apexification were evaluated. Teeth with unintentionally extruded MTA formed the study group (Group 1, n = 28), whereas the teeth with no MTA extrusion formed the control group (Group 2, n = 47). For both the groups, the records were analyzed for a follow-up period of 3 years. RESULTS: Complete healing (CH) was observed in 25 teeth in the study group, whereas all the teeth in the control group showed CH (P > 0.05). Within the study group, 6 teeth (21%) showed CH in the 6th month in Group 1, whereas in the control group, 34 teeth (72.3%) showed CH (P < 0.001). At the 1-year follow-up appointment, 19 teeth (67.8%) showed CH in Group 1, whereas 9 teeth (19.1%) showed the same result in Group 2 (P < 0.001). At the end of the 3-year follow-up period, it was noticed that in 21 (84%) teeth, extruded MTA remained unchanged, whereas it was reduced in 4 (16%) of them (P < 0.001). CONCLUSION: Extrusion of MTA does not have a significant effect on the healing of the periapical lesion. However, it may lead to a delay in the healing of periapical healing. Patients should be informed about the complication and consequences of extruded MTA and should be kept on follow-up to observe periapical healing.

Evaluation of Preoperative Salivary Cortisol Level in Patients Undergoing Major Maxillofacial Surgery.

AIM: The main purpose of the study was to compare the preoperative salivary cortisol levels 3 days before the major surgery under general anesthesia and to compare it with the patients undergoing extraction under local anesthesia. MATERIALS AND METHODS: Forty-two patients were undergoing major surgery and 42 age- and sex-matched patients undergoing dental extraction were included and their salivary cortisol levels were analyzed before and after the dental procedure. RESULTS: Results showed that there is a significant increase in the mean salivary cortisol concentration after extraction (23.7 ± 9.2) than before extraction (18.9 ± 23.7) in the study group (P = 0.015) as well as in the control group. The comparison between salivary cortisol in the study group before (18.9 ± 23.7) and after (23.7 ± 9.2) surgery was significantly higher than the control group (15.2 ± 5.5) (P = 0.013 and 0.005), respectively. CONCLUSION: We have concluded from this study that the salivary cortisol level shows a significant increase on the day of surgery.

A multiple ion-uptake phenotyping platform reveals shared mechanisms affecting nutrient uptake by roots.

Nutrient uptake is critical for crop growth and is determined by root foraging in soil. Growth and branching of roots lead to effective root placement to acquire nutrients, but relatively little is known about absorption of nutrients at the root surface from the soil solution. This knowledge gap could be alleviated by understanding sources of genetic variation for short-term nutrient uptake on a root length basis. A modular platform called RhizoFlux was developed for high-throughput phenotyping of multiple ion-uptake rates in maize (Zea mays L.). Using this system, uptake rates were characterized for the crop macronutrients nitrate, ammonium, potassium, phosphate, and sulfate among the Nested Association Mapping (NAM) population founder lines. The data revealed substantial genetic variation for multiple ion-uptake rates in maize. Interestingly, specific nutrient uptake rates (nutrient uptake rate per length of root) were found to be both heritable and distinct from total uptake and plant size. The specific uptake rates of each nutrient were positively correlated with one another and with specific root respiration (root respiration rate per length of root), indicating that uptake is governed by shared mechanisms. We selected maize lines with high and low specific uptake rates and performed an RNA-seq analysis, which identified key regulatory components involved in nutrient uptake. The high-throughput multiple ion-uptake kinetics pipeline will help further our understanding of nutrient uptake, parameterize holistic plant models, and identify breeding targets for crops with more efficient nutrient acquisition.

Three Common Symbiotic ABC Subfamily B Transporters in Medicago truncatula Are Regulated by a NIN-Independent Branch of the Symbiosis Signaling Pathway.

Several ATP-binding cassette (ABC) transporters involved in the arbuscular mycorrhizal symbiosis and nodulation have been identified. We describe three previously unreported ABC subfamily B transporters, named AMN1, AMN2, and AMN3 (ABCB for mycorrhization and nodulation), that are expressed early during infection by rhizobia and arbuscular mycorrhizal fungi. These ABCB transporters are strongly expressed in symbiotically infected tissues, including in root-hair cells with rhizobial infection threads and arbusculated cells. During nodulation, the expression of these genes is highly induced by rhizobia and purified Nod factors and is dependent on DMI3 but is not dependent on other known major regulators of infection, such as NIN, NSP1, or NSP2. During mycorrhization their expression is dependent on DMI3 and RAM1 but not on NSP1 and NSP2. Therefore, they may be commonly regulated through a distinct branch of the common symbiotic pathway. Mutants with exonic Tnt1-transposon insertions were isolated for all three genes. None of the single or double mutants showed any differences in colonization by either rhizobia or mycorrhizal fungi, but the triple amn1 amn2 amn3 mutant showed an increase in nodule number. Further studies are needed to identify potential substrates of these transporters and understand their roles in these beneficial symbioses.[Formula: see text] Copyright © 2021 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.

Application of Synthetic Peptide CEP1 Increases Nutrient Uptake Rates Along Plant Roots.

The root system of a plant provides vital functions including resource uptake, storage, and anchorage in soil. The uptake of macro-nutrients like nitrogen (N), phosphorus (P), potassium (K), and sulphur (S) from the soil is critical for plant growth and development. Small signaling peptide (SSP) hormones are best known as potent regulators of plant growth and development with a few also known to have specialized roles in macronutrient utilization. Here we describe a high throughput phenotyping platform for testing SSP effects on root uptake of multiple nutrients. The SSP, CEP1 (C-TERMINALLY ENCODED PEPTIDE) enhanced nitrate uptake rate per unit root length in Medicago truncatula plants deprived of N in the high-affinity transport range. Single structural variants of M. truncatula and Arabidopsis thaliana specific CEP1 peptides, MtCEP1D1:hyp4,11 and AtCEP1:hyp4,11, enhanced uptake not only of nitrate, but also phosphate and sulfate in both model plant species. Transcriptome analysis of Medicago roots treated with different MtCEP1 encoded peptide domains revealed that hundreds of genes respond to these peptides, including several nitrate transporters and a sulfate transporter that may mediate the uptake of these macronutrients downstream of CEP1 signaling. Likewise, several putative signaling pathway genes including LEUCINE-RICH REPEAT RECPTOR-LIKE KINASES and Myb domain containing transcription factors, were induced in roots by CEP1 treatment. Thus, a scalable method has been developed for screening synthetic peptides of potential use in agriculture, with CEP1 shown to be one such peptide.

Arsenic induced alteration in Mrp-1 like activity leads to zebrafish hepatocyte apoptosis: The cellular GSH connection.

Multidrug-resistance protein-1 facilitates the efflux of arsenic conjugated with reduced glutathione nonetheless; the relation between Mrp-1 ATPase activity and cellular GSH levels is contentious. To study this, Mrp-1-ATPase activity was measured in 5 µM arsenic trioxide exposed zebrafish hepatocytes (ZFH) and correlated with intracellular GSH levels. Alongside, mrp-1 gene expression as well as Mrp-1 protein level was also monitored. Diverse mode of Mrp-1 inhibition was reflected from differential level of Km and Vmax of Mrp-1 at different time points. 3 h post-arsenic treatment demonstrated non-competitive inhibition. At 6 h, there was significant increase in Km and ZFH death, suggesting reduced binding affinity of Mrp-1 for ATP. Increased caspase-9-cytochromeC-ATP levels (putative apoptosome), reinforced ZFH apoptosis. The increase in Vmax coupled with reduced substrate affinity of Mrp-1 suggests malfunctioning in arsenic- tolerance mechanisms. We posit the triggering glutathione level regulate arsenic tolerance in ZFH. Irreversible impairment of ATP binding to Mrp-1 culminates in arsenic-induced ZFH apoptosis.

MtSSPdb: The Medicago truncatula Small Secreted Peptide Database.

A growing number of small secreted peptides (SSPs) in plants are recognized as important regulatory molecules with roles in processes such as growth, development, reproduction, stress tolerance, and pathogen defense. Recent discoveries further implicate SSPs in regulating root nodule development, which is of particular significance for legumes. SSP-coding genes are frequently overlooked, because genome annotation pipelines generally ignore small open reading frames, which are those most likely to encode SSPs. Also, SSP-coding small open reading frames are often expressed at low levels or only under specific conditions, and thus are underrepresented in non-tissue-targeted or non-condition-optimized RNA-sequencing projects. We previously identified 4,439 SSP-encoding genes in the model legume Medicago truncatula To support systematic characterization and annotation of these putative SSP-encoding genes, we developed the M. truncatula Small Secreted Peptide Database (MtSSPdb; https://mtsspdb.noble.org/). MtSSPdb currently hosts (1) a compendium of M. truncatula SSP candidates with putative function and family annotations; (2) a large-scale M. truncatula RNA-sequencing-based gene expression atlas integrated with various analytical tools, including differential expression, coexpression, and pathway enrichment analyses; (3) an online plant SSP prediction tool capable of analyzing protein sequences at the genome scale using the same protocol as for the identification of SSP genes; and (4) information about a library of synthetic peptides and root and nodule phenotyping data from synthetic peptide screens in planta. These datasets and analytical tools make MtSSPdb a unique and valuable resource for the plant research community. MtSSPdb also has the potential to become the most complete database of SSPs in plants.

Celebrating 20 Years of Genetic Discoveries in Legume Nodulation and Symbiotic Nitrogen Fixation.

Since 1999, various forward- and reverse-genetic approaches have uncovered nearly 200 genes required for symbiotic nitrogen fixation (SNF) in legumes. These discoveries advanced our understanding of the evolution of SNF in plants and its relationship to other beneficial endosymbioses, signaling between plants and microbes, the control of microbial infection of plant cells, the control of plant cell division leading to nodule development, autoregulation of nodulation, intracellular accommodation of bacteria, nodule oxygen homeostasis, the control of bacteroid differentiation, metabolism and transport supporting symbiosis, and the control of nodule senescence. This review catalogs and contextualizes all of the plant genes currently known to be required for SNF in two model legume species, Medicago truncatula and Lotus japonicus, and two crop species, Glycine max (soybean) and Phaseolus vulgaris (common bean). We also briefly consider the future of SNF genetics in the era of pan-genomics and genome editing.

Identification and Functional Investigation of Genome-Encoded, Small, Secreted Peptides in Plants.

Hundreds to thousands of small secreted peptides (SSPs) are encoded in plant genomes but have been overlooked, and most remain unannotated and unstudied. Despite their low profile, they have been found to confer dramatic effects on growth and development of plants. With the growing appreciation of their significance, the development of appropriate methods to identify and functionally assess the myriad SSPs encoded in plant genomes has become critical. Here, we provide protocols for the computational and physiological analysis of SSPs in plant genomes. We first describe our methodology successfully used for genome-wide identification and annotation of SSP-coding genes in the model legume Medicago truncatula, which can be readily adapted for other plant species. We then provide protocols for the functional analysis of SSPs using various synthetic peptide screens. Considerations for the design and handling of peptides are included. © 2019 by John Wiley & Sons, Inc.

Blue-fluorescent and biocompatible carbon dots derived from abundant low-quality coals.

Coal is one of the most abundant natural carbonaceous materials. This paper reports a novel oxidative chemical method for the synthesis of high-value carbon dots (CDs) from cheap and abundant low-quality high­sulfur coals for use in high-end applications. These CDs were synthesized by using wet-chemical ultrasonic stimulation-induced process which is environmentally facile and less drastic compared to other chemical methods of production of CDs. The sizes of the synthesized CDs from different types of coal samples were estimated to be in the range of 1-4 nm, 1-6 nm, 2-5 nm, and 10-30 nm. The quantum yield (QY) of the CDs was determined and it was found to be around 3-14%. For high-end field application, the CDs were further tested for toxicity and were reported to be safe for environmental and biological applications. The cell image analysis under the fluorescence microscope further indicated that the synthesized CDs could be used as a promising bio-compatible material for optical-imaging as well as bio-imaging. The CDs showed promising fluorescent sensing property and can be utilized as a good probe for silver ion detection/sensing. The CDs is also found to be a promising reagent for silver nanoparticles synthesis. The results provide a new avenue for large-scale synthesis of CDs.

Reattachment of complex fractures; a reality by advances in self-etch bonding systems.

An 18-year-old female patient reported to the Department of Conservative and Endodontics with the chief complaint of fractured tooth with respect to 21 and increased pain and mobility tooth with respect to 22. Intraoral periapical radiograph of 21 revealed coronal loss of tooth structure involving enamel, dentin, and pulp, suggestive of split tooth with respect to 21. Intraoral examination revealed a fracture of coronal structure of 22 and increased mobility in the coronal aspect, suggestive of horizontal crown-root fracture. For management of 21, after endodontic phase, placement of fiberpost, and coronal buildup, intentional reimplantation was done to expose and reattach the vertically fractured root fragment. For management of 22, after endodontic phase, crown lengthening was done, and the fractured fragment was reattached by making it a Natural Richmond's Crown. Radiographs revealed a complete sealing of the fractured fragment and proper positioning of the tooth.

NIN Acts as a Network Hub Controlling a Growth Module Required for Rhizobial Infection.

The symbiotic infection of root cells by nitrogen-fixing rhizobia during nodulation requires the transcription factor Nodule Inception (NIN). Our root hair transcriptomic study extends NIN's regulon to include Rhizobium Polar Growth and genes involved in cell wall modification, gibberellin biosynthesis, and a comprehensive group of nutrient (N, P, and S) uptake and assimilation genes, suggesting that NIN's recruitment to nodulation was based on its role as a growth module, a role shared with other NIN-Like Proteins. The expression of jasmonic acid genes in nin suggests the involvement of NIN in the resolution of growth versus defense outcomes. We find that the regulation of the growth module component Nodulation Pectate Lyase by NIN, and its function in rhizobial infection, are conserved in hologalegina legumes, highlighting its recruitment as a major event in the evolution of nodulation. We find that Nodulation Pectate Lyase is secreted to the infection chamber and the lumen of the infection thread. Gene network analysis using the transcription factor mutants for ERF Required for Nodulation1 and Nuclear Factor-Y Subunit A1 confirms hierarchical control of NIN over Nuclear Factor-Y Subunit A1 and shows that ERF Required for Nodulation1 acts independently to control infection. We conclude that while NIN shares functions with other NIN-Like Proteins, the conscription of key infection genes to NIN's control has made it a central regulatory hub for rhizobial infection.