Life stage-specific poly(A) site selection regulated by Trypanosoma brucei DRBD18.

The kinetoplastid parasite, Trypanosoma brucei, undergoes a complex life cycle entailing slender and stumpy bloodstream forms in mammals and procyclic and metacyclic forms (MFs) in tsetse fly hosts. The numerous gene regulatory events that underlie T. brucei differentiation between hosts, as well as between active and quiescent stages within each host, take place in the near absence of transcriptional control. Rather, differentiation is controlled by RNA-binding proteins (RBPs) that associate with mRNA 3' untranslated regions (3'UTRs) to impact RNA stability and translational efficiency. DRBD18 is a multifunctional T. brucei RBP, shown to impact mRNA stability, translation, export, and processing. Here, we use single-cell RNAseq to characterize transcriptomic changes in cell populations that arise upon DRBD18 depletion, as well as to visualize transcriptome-wide alterations to 3'UTR length. We show that in procyclic insect stages, DRBD18 represses expression of stumpy bloodstream form and MF transcripts. Additionally, DRBD18 regulates the 3'UTR lengths of over 1,500 transcripts, typically promoting the use of distal polyadenylation sites, and thus the inclusion of 3'UTR regulatory elements. Remarkably, comparison of polyadenylation patterns in DRBD18 knockdowns with polyadenylation patterns in stumpy bloodstream forms shows numerous similarities, revealing a role for poly(A) site selection in developmental gene regulation, and indicating that DRBD18 controls this process for a set of transcripts. RNA immunoprecipitation supports a direct role for DRBD18 in poly(A) site selection. This report highlights the importance of alternative polyadenylation in T. brucei developmental control and identifies a critical RBP in this process.

On the origin of the biological effects of time varying magnetic fields: quantitative insights.

In a number of recently published experimental studies from our research group, the positive impact of magnetic stimuli (static/pulsed) on cell functionality modulation or bactericidal effects, in vitro, has been established. In order to develop a theoretical understanding of such magnetobiological effects, the present study aimed to present two quantitative models to determine magnetic Maxwell stresses as well as pressure acting on the cell membrane, under the influence of a time varying magnetic field. The model predicts that magnetic field-induced stress on the cell/bacteria is dependent on the conductivity properties of the extracellular region, which is determined to be too low to cause any significant effect. However, the force on the cell/bacteria due to the induced electric field is more influential than that of the magnetic field, which has been used to determine the membrane tension that can cause membrane poration. With a known critical membrane tension for cells, the field parameters necessary to cause membrane rupture have been estimated. Based on the experimental results and theoretically predicted values, the field parameters can be classified into three regimes, wherein the magnetic fields cause no effect or result in biophysical stimulation or induce cell death due to membrane damage. Taken together, this work provides some quantitative insights into the impact of magnetic fields on biological systems.

Deep eutectic solvents: Preparation, properties, and food applications.

Deep Eutectic Solvents (DESs) emerge as innovative 21st-century solvents, supplanting traditional ones like ethanol and n-hexane. Renowned for their non-toxic, biodegradable, and water-miscible nature with reduced volatility, DESs are mostly synthesized through heating and stirring method. Physicochemical properties such as polarity, viscosity, density and surface tension of DESs influenced their application. This review paper gives the overview of application of eco-benign DESs in fruits, vegetables, cereals, pulses, spices, herbs, plantation crops, oil seed crops, medicinal and aromatic plants, seaweed, and milk for the extraction of bioactive compounds. Also, it gives insight of determination of pesticides, insecticides, hazardous and toxic compounds, removal of heavy metals, detection of illegal milk additive, purification of antibiotics and preparation of packaging film. Methodologies for separating bioactive compounds from DESs extracts are systematically examined. Further, safety regulations of DESs are briefly discussed and reviewed literature reveals prevalent utilization of DES-based bioactive compound rich extracts in cosmetics, indicating untapped potential of their application in the food industry.

A Perspective on Various Facets of Nanoemulsions and its Commercial Utilities.

Nanotechnology is a captivating contemporary technology owing to its extensive range of potential applications. This study emphasizes nanomaterials, substances with a size <100 nm, offering better qualities than coarse particles. Nanoparticles have several advantages compared with conventional drug delivery methods, including enhanced bioavailability and a larger surface area because of their smaller particle size. These characteristics make the nanoparticles a viable clinical candidate. Controlled-release drug delivery systems and targeted drug delivery systems rely heavily on nanoparticles. Because traditional drug delivery methods fail to achieve targeted drug delivery, resulting in toxicity, low bioavailability, poor therapeutic outcomes, and so on, these drug nanoparticles excel in all these areas. Researchers are already interested in developing drug delivery systems such as niosomes, bilosomes, and dendrimers. Nanoemulsion is one of these technologies; nanoemulsions outperform traditional emulsions in terms of pharmacodynamics and pharmacokinetics. Nanoemulsion effectively surpasses the constraints of standard emulsions, primarily by offering enhanced bioavailability, reduced toxicity, improved absorption, and the potential to be used in targeted drug delivery or controlled-release drug delivery systems. This particular work explores several aspects of nanoemulsions, including their constituents, classification, techniques for preparation, criteria for assessment, commercial applications, and future prospects.

Biomineralized fluorocanasite-reinforced biocomposite scaffolds demonstrate expedited osteointegration of critical-sized bone defects.

The development of patient-specific bone scaffolds that can expedite bone regeneration has been gaining increased attention, especially for critical-sized bone defects or fractures. Precise adaptation of the scaffold to the region of implantation and reduced surgery times are also crucial at clinical scales. To this end, bioactive fluorcanasite glass-ceramic microparticulates were incorporated within a biocompatible photocurable resin matrix following which the biocomposite resin precursor was 3D-printed with digital light processing method to develop the bone scaffold. The printing parameters were optimized based on spot curing investigation, particle size data, and UV-visible spectrophotometry. In vitro cell culture with MG-63 osteosarcoma cell lines and pH study within simulated body fluid demonstrated a noncytotoxic response of the scaffold samples. Further, the in vivo bone regeneration ability of the 3D-printed biocomposite bone scaffolds was investigated by implantation of the scaffold samples in the rabbit femur bone defect model. Enhanced angiogenesis, osteoblastic, and osteoclastic activities were observed at the bone-scaffold interface, while examining through fluorochrome labelling, histology, radiography, field emission scanning electron microscopy, and x-ray microcomputed tomography. Overall, the results demonstrated that the 3D-printed biocomposite bone scaffolds have promising potential for bone loss rehabilitation.

Drug kinetics and antimicrobial properties of quaternary bioactive glasses 81S(81SiO2-(16-x)CaO-2P2O5-1Na2O-xMgO); an in-vitro study.

Bioactive glasses have recently been attracted to meet the challenge in bone tissue regeneration, repair, healing, dental implants, etc. Among the conventional bio-glasses, a novel quaternary mesoporous nano bio-glass with composition 81S(81SiO2-(16-x)CaO-2P2O5-1Na2O-xMgO) (x = 0, 1.6, 2.4, 4 and 8 mol%) employing Stober's method has been explored for examining the above potential application through in-vitro SBF assay, MTT assay, antimicrobial activity and drug loading and release ability. With increasing the MgO concentration up to 4 mol%, from in-vitro SBF assay, we observe that HAp layer develops on the surface of the nBGs confirmed from XRD, FTIR and FESEM. MTT assay using MG-63 cells confirms the biocompatibility of the nBGs having cell viability >225 % for MGO_4 after 72 h which is more than the clinically used 45S5 bio-glass. We have observed cell viability of >125 % even after 168 h. Moreover, MGO_4 is found to restrict the growth of E. coli by 65 % while S. aureus by 75 %, confirming the antimicrobial activity. Despite an increase in the concentration of magnesium, nBGs are found to be non-toxic towards the RBCs up to 4 mol% of MgO while for 8 %, the hemolysis percentage is >6 % which is toxic. Being confirmed MGO_4 nBG as a bioactive material, various concentrations of drug (Dexamethasone (DEX)) loading and release kinetics are examined. We show that 80 % of loading in case of 10 mg-ml-1 and 70 % of cumulative release in 100 h. The mesoporous structure of MGO_4 having an average pore diameter of 5 nm and surface area of 216 m2 g-1 confirmed from BET supports the loading and release kinetics. We conclude that the quaternary MGO_4 nBG may be employed effectively for bone tissue regeneration due to its high biocompatibility, excellent in-vitro cell viability, antimicrobial response and protracted drug release.

Accelerated Osteogenic Response of Electrodynamically Stimulated Mg1-xCaxSi1-xZrxO3 (x = 0-0.4) Bioelectrets.

MgSiO3-based biodegradable ceramics demonstrated remarkable potential for treating small-scale bone defects and temporary bone replacement. In addition, the dissolution behavior of MgSiO3 bioceramics can be tuned by doping of Ca and Zr elements at Mg and Si sites, respectively. The present study reported the influence of formation of Ca- and Zr-codoped Mg1-xCaxSi1-xZrxO3 (x = 0, 0.1, 0.2, 0.3, and 0.4) bioelectrets and electrodynamic stimulation toward improving their osteogenic response. Mg1-xCaxSi1-xZrxO3 electrets were successfully synthesized by a solid-state route. A detailed X-ray photoelectron spectroscopy (XPS) analyses revealed that the electrets produced oxygen-deficient active sites. The formation of Mg1-xCaxSi1-xZrxO3 electrets significantly increased the surface hydrophilicity. Inductively coupled plasma (ICP) analyses were used to examine the leaching behavior of Ca/Zr-codoped MgSiO3 bioceramics. In vitro cell culture analyses indicated that the osteogenesis of MG-63 cells was remarkably enhanced on the electrodynamic field-treated Mg1-xCaxSi1-xZrxO3 bioelectrets as compared to hydroxyapatite (HA). Moreover, a better osteogenic response was observed for higher concentrations of Ca (0.3 and 0.4) and Zr (0.3 and 0.4) doping in the MgSiO3 bioelectrets. Further, the mechanism of enhanced cellular functionality was revealed by the measurement of intracellular Ca2+.

Translational control by Trypanosoma brucei DRBD18 contributes to the maintenance of the procyclic state.

Trypanosoma brucei occupies distinct niches throughout its life cycle, within both the mammalian and tsetse fly hosts. The immunological and biochemical complexity and variability of each of these environments require a reshaping of the protein landscape of the parasite both to evade surveillance and face changing metabolic demands. In kinetoplastid protozoa, including T. brucei, posttranscriptional control mechanisms are the primary means of gene regulation, and these are often mediated by RNA-binding proteins. DRBD18 is a T. brucei RNA-binding protein that reportedly interacts with ribosomal proteins and translation factors. Here, we tested a role for DRBD18 in translational control. We validate the DRBD18 interaction with translating ribosomes and the translation initiation factor, eIF3a. We further show that DRBD18 depletion by RNA interference leads to altered polysomal profiles with a specific depletion of heavy polysomes. Ribosome profiling analysis reveals that 101 transcripts change in translational efficiency (TE) upon DRBD18 depletion: 41 exhibit decreased TE and 60 exhibit increased TE. A further 66 transcripts are buffered, that is, changes in transcript abundance are compensated by changes in TE such that the total translational output is expected not to change. In DRBD18-depleted cells, a set of transcripts that codes for procyclic form-specific proteins is translationally repressed while, conversely, transcripts that code for bloodstream form- and metacyclic form-specific proteins are translationally enhanced. RNA immunoprecipitation/qRT-PCR indicates that DRBD18 associates with members of both repressed and enhanced cohorts. These data suggest that DRBD18 contributes to the maintenance of the procyclic state through both positive and negative translational control of specific mRNAs.

Piezoelectric nanogenerators for self-powered wearable and implantable bioelectronic devices.

One of the recent innovations in the field of personalized healthcare is the piezoelectric nanogenerators (PENGs) for various clinical applications, including self-powered sensors, drug delivery, tissue regeneration etc. Such innovations are perceived to potentially address some of the unmet clinical needs, e.g., limited life-span of implantable biomedical devices (e.g., pacemaker) and replacement related complications. To this end, the generation of green energy from biomechanical sources for wearable and implantable bioelectronic devices gained considerable attention in the scientific community. In this perspective, this article provides a comprehensive state-of-the-art review on the recent developments in the processing, applications and associated concerns of piezoelectric materials (synthetic/biological) for personalized healthcare applications. In particular, this review briefly discusses the concepts of piezoelectric energy harvesting, piezoelectric materials (ceramics, polymers, nature-inspired), and the various applications of piezoelectric nanogenerators, such as, self-powered sensors, self-powered pacemakers, deep brain stimulators etc. Important distinction has been made in terms of the potential clinical applications of PENGs, either as wearable or implantable bioelectronic devices. While discussing the potential applications as implantable devices, the biocompatibility of the several hybrid devices using large animal models is summarized. This review closes with the futuristic vision of integrating data science approaches in developmental pipeline of PENGs as well as clinical translation of the next generation PENGs. STATEMENT OF SIGNIFICANCE: Piezoelectric nanogenerators (PENGs) hold great promise for transforming personalized healthcare through self-powered sensors, drug delivery systems, and tissue regeneration. The limited battery life of implantable devices like pacemakers presents a significant challenge, leading to complications from repititive surgeries. To address such a critical issue, researchers are focusing on generating green energy from biomechanical sources to power wearable and implantable bioelectronic devices. This comprehensive review critically examines the latest advancements in synthetic and nature-inspired piezoelectric materials for PENGs in personalized healthcare. Moreover, it discusses the potential of piezoelectric materials and data science approaches to enhance the efficiency and reliability of personalized healthcare devices for clinical applications.

LTE-NBP with holistic UWB-WBAN approach for the energy efficient biomedical application.

Increased use of ultra-wideband (UWB) in biomedical applications based on wireless body area networks (WBAN) opens a variety of options in the field of biomedical research. WBAN may aid in the continuous health monitoring of patients while they go about their everyday lives. Many studies and researchers were conducted several experimentations in the same field for the performance improvement. This study covered the hybridization of UWB technology, as well as on-body, off-body, and human-body ultra-wideband communication (HB-UWB). In this paper, the parameters considered are throughput, energy consumption, energy efficiency, energy used, network survival and delay. An improved model for design and assessment of power-saving UWB-WBAN was developed in this paper. A novel protocol model was introduced in this paper, namely low-power traffic-aware emergency based narrowband protocol (LTE-NBP) to overcome the major drawbacks of emergency, critical data transmission, reliability and the power issues in UWB-WBAN. It's the emergency-based low-power traffic-aware narrowband protocol. It is based on the dual-band physical layer technology. The suggested protocol considered an aware traffic model and an emergency medium access control (MAC) protocol. The proposed model's performance was evaluated and compared with the related algorithms on different performance parameters. The improved model is found to be efficient in throughput, energy efficiency, energy consumption, and delay.

KREH1 RNA helicase activity promotes utilization of initiator gRNAs across multiple mRNAs in trypanosome RNA editing.

Mitochondrial U-indel RNA editing in kinetoplastid protozoa is directed by trans-acting gRNAs and mediated by a holoenzyme with associated factors. Here, we examine the function of the holoenzyme-associated KREH1 RNA helicase in U-indel editing. We show that KREH1 knockout (KO) impairs editing of a small subset of mRNAs. Overexpression of helicase-dead mutants results in expanded impairment of editing across multiple transcripts, suggesting the existence of enzymes that can compensate for KREH1 in KO cells. In depth analysis of editing defects using quantitative RT-PCR and high-throughput sequencing reveals compromised editing initiation and progression in both KREH1-KO and mutant-expressing cells. In addition, these cells exhibit a distinct defect in the earliest stages of editing in which the initiator gRNA is bypassed, and a small number of editing events takes place just outside this region. Wild type KREH1 and a helicase-dead KREH1 mutant interact similarly with RNA and holoenzyme, and overexpression of both similarly disorders holoenzyme homeostasis. Thus, our data support a model in which KREH1 RNA helicase activity facilitates remodeling of initiator gRNA-mRNA duplexes to permit accurate utilization of initiating gRNAs on multiple transcripts.

Effect of carbon quantum dots derived from extracts of UV-B-exposed Eclipta alba on alcohol-induced liver cirrhosis in Golden Hamster.

The Eclipta alba plant is considered hepatoprotective, owing to its phytoconstituents wedelolactone. In the current study, effect of elevated ultraviolet-B (eUV-B) radiation was investigated on biochemical, phytochemical, and antioxidative enzymatic activities of E. alba (Bhringraj) plant. The UV-B exposure resulted in an increase in oxidative stress, which has caused an imbalance in phytochemical, biochemical constituents, and induced antioxidative enzymatic activities. It was observed that the UV-B exposure promoted wedelolactone yield by 23.64%. Further, the leaf extract of UV-B-exposed plants was used for the synthesis of carbon quantum dots (CQDs) using low cost, one-step hydrothermal technique and its biocompatibility was studied using in vitro MTT (3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide) assay on HepG2 liver cell line. It revealed no toxicity in any treatment groups in comparison to the control. Both CQDs and leaf extract were orally administered to the golden hamster suffering from alcohol-induced liver cirrhosis. In the morphometric study, it was clearly observed that a combination of UV-B-exposed leaf extract and synthesized CQDs delivered the best result with maximum recovery of liver tissues. The present study reveals the positive impact of UV-B exposure on the medicinally important plant, increased yield of wedelolactone, and its enhanced hepatoprotective efficacy for the treatment of damaged liver tissues.

Concepts of circular economy for sustainable management of electronic wastes: challenges and management options.

The electronic and electrical industrial sector is exponentially growing throughout the globe, and sometimes, these wastes are being disposed of and discarded with a faster rate in comparison to the past era due to technology advancements. As the application of electronic devices is increasing due to the digitalization of the world (IT sector, medical, domestic, etc.), a heap of discarded e-waste is also being generated. Per-capita e-waste generation is very high in developed countries as compared to developing countries. Expansion of the global population and advancement of technologies are mainly responsible to increase the e-waste volume in our surroundings. E-waste is responsible for environmental threats as it may contain dangerous and toxic substances like metals which may have harmful effects on the biodiversity and environment. Furthermore, the life span and types of e-waste determine their harmful effects on nature, and unscientific practices of their disposal may elevate the level of threats as observed in most developing countries like India, Nigeria, Pakistan, and China. In the present review paper, many possible approaches have been discussed for effective e-waste management, such as recycling, recovery of precious metals, adopting the concepts of circular economy, formulating relevant policies, and use of advance computational techniques. On the other hand, it may also provide potential secondary resources valuable/critical materials whose primary sources are at significant supply risk. Furthermore, the use of machine learning approaches can also be useful in the monitoring and treatment/processing of e-wastes. HIGHLIGHTS: In 2019, ~ 53.6 million tons of e-wastes generated worldwide. Discarded e-wastes may be hazardous in nature due to presence of heavy metal compositions. Precious metals like gold, silver, and copper can also be procured from e-wastes. Advance tools like artificial intelligence/machine learning can be useful in the management of e-wastes.

An in vivo toxicity assessment of piezoelectric sodium potassium niobate [NaxK1-xNbO3 (x = 0.2-0.8)] nanoparticulates towards bone tissue engineering approach.

One of the recent challenges in the design/development of prosthetic orthopedic implants is to address the concern of local/systemic toxicity of debris particles, released due to wear or degradation. Such debris particles often lead to inflammation at the implanted site or aseptic loosening of the prosthesis which results in failure of the implant during long run. Several in vitro studies demonstrated the potentiality of piezoelectric sodium potassium niobate [NaxK1-xNbO3 (x = 0.2, 0.5, 0.8), NKN] as an emerging next-generation polarizable orthopedic implant. In this perspective, we performed an in vivo study to examine the local and systemic toxicity of NKN nanoparticulates, as a first report. In the present study, male Wistar rats were intra-articularly injected to the knee joint with 100 µl of NKN nanoparticulates (25 mg/ml in normal saline). After 7 days of exposure, the histopathological analyses demonstrate the absence of any inflammation or dissemination of nanoparticulates in vital organs such as heart, liver, kidney and spleen. The anti-inflammatory cytokines (IL-4 and IL-10) profile analyses suggest the increased anti-inflammatory response in the treated rats as compared to non-injected (control) rats, preferably for the sodium and potassium rich NKN i.e., Na0.8K0.2NbO3 and Na0.2K0.8NbO3. The biochemical analyses revealed no pathological changes in the liver and kidney of particulate treated rats. The present study is the first proof to confirm the non-toxic nature of NKN nanoparticulates which provides a step forward towards the development of prosthetic orthopedic implants using biocompatible piezoelectric NKN ceramics.

Interplay of surface polarization charge, dynamic electrical stimulation and compositional modification towards accelerated osteogenic response of NaxK1-xNbO3 piezo-bioceramics.

Bone remodeling processes involve endogenous bioelectrical signals such as piezoelectric charges. Moreover, external electrical stimulation helps in improving the healing capability of injured tissues by modulating the metabolic signaling pathways of cells. Towards this end, the present study reveals the influence of the combined action of electrostatic surface polarization charge and dynamic pulsed electrical stimulation alongwith compositional modification towards improving the osteogenic response of emerging piezo-bioceramics, sodium potassium niobate [NaxK1-xNbO3 (x = 0.2-0.8), NKN]. The dependence of crystal structure on compositions (x) was retrieved by Rietveld refinement and X-ray peak profile analyses. The surface charge, stored in the polarized (@ 25 kV at 500 °C) NaxK1-xNbO3 (x = 0.2, 0.5, 0.8) samples were measured to be 0.52, 0.50 and 0.47 µC/cm2, respectively, using thermally stimulated depolarized current (TSDC). X-ray photoelectron spectroscopy (XPS) survey scan spectra revealed that the polarization process does not alter the surface chemistry of NKN. Negatively charged surfaces are observed to accelerate early-stage adhesion of osteoblast-like cells which further results in enhanced spreading of adhered cells. Subsequently, the dynamic pulsed electrical stimulation of 1 V/cm with the pulse duration of 400 µs was applied, while the cells were being adhered on electrostatically charged surfaces. The quantitative and qualitative analyses revealed that the synergistic action of electrostatic surface polarization charge and dynamic pulsed electrical stimulation further accelerates cell proliferation and differentiation on negatively charged surfaces of Na and K-rich compositions of NKN. The mechanism of augmented cellular activity was analyzed using intracellular Ca2+ measurement.

Deciphering the role of the two conserved motifs of the ECF41 family σ factor in the autoregulation of its own promoter in Azospirillum brasilense Sp245.

In Azospirillum brasilense, an extra-cytoplasmic function σ factor (RpoE10) shows the characteristic 119 amino acid long C-terminal extension found in ECF41-type σ factors, which possesses three conserved motifs (WLPEP, DGGGR, and NPDKV), one in the linker region between the σ2 and σ4 , and the other two in the SnoaL_2 domain of the C-terminal extension. Here, we have described the role of the two conserved motifs in the SnoaL_2 domain of RpoE10 in the inhibition and activation of its activity, respectively. Truncation of the distal part of the C-terminal sequence of the RpoE10 (including NPDKV but excluding the DGGGR motif) results in its promoter's activation suggesting autoregulation. Further truncation of the C-terminal sequence up to its proximal part, including NPDKV and DGGGR motif, abolished promoter activation. Replacement of NPDKV motif with NAAAV in RpoE10 increased its ability to activate its promoter, whereas replacement of DGGGR motif led to reduced promoter activation. We have explored the dynamic modulation of σ2 -σ4 domains and the relevant molecular interactions mediated by the two conserved motifs of the SnoaL2 domain using molecular dynamics simulation. The analysis enabled us to explain that the NPDKV motif located distally in the C-terminus negatively impacts transcriptional activation. In contrast, the DGGGR motif found proximally of the C-terminal extension is required to activate RpoE10.

ß-Lactam Resistance in Azospirillum baldaniorum Sp245 Is Mediated by Lytic Transglycosylase and ß-Lactamase and Regulated by a Cascade of RpoE7→RpoH3 Sigma Factors.

Bacterial resistance to ß-lactam antibiotics is often mediated by ß-lactamases and lytic transglycosylases. Azospirillum baldaniorum Sp245 is a plant-growth-promoting rhizobacterium that shows high levels of resistance to ampicillin. Investigating the molecular basis of ampicillin resistance and its regulation in A. baldaniorum Sp245, we found that a gene encoding lytic transglycosylase (Ltg1) is organized divergently from a gene encoding an extracytoplasmic function (ECF) σ factor (RpoE7) in its genome. Inactivation of rpoE7 in A. baldaniorum Sp245 led to increased ability to form cell-cell aggregates and produce exopolysaccharides and biofilm, suggesting that rpoE7 might contribute to antibiotic resistance. Inactivation of ltg1 in A. baldaniorum Sp245, however, adversely affected its growth, indicating a requirement of Ltg1 for optimal growth. The expression of rpoE7, as well that of as ltg1, was positively regulated by RpoE7, and overexpression of RpoE7 conferred ampicillin sensitivity to both the rpoE7::km mutant and its parent. In addition, RpoE7 negatively regulated the expression of a gene encoding a ß-lactamase (bla1). Out of the 5 paralogs of RpoH encoded in the genome of A. baldaniorum Sp245, RpoH3 played major roles in conferring ampicillin sensitivity and in the downregulation of bla1. The expression of rpoH3 was positively regulated by RpoE7. Collectively, these observations reveal a novel regulatory cascade of RpoE7-RpoH3 σ factors that negatively regulates ampicillin resistance in A. baldaniorum Sp245 by controlling the expression of a ß-lactamase and a lytic transglycosylase. In the absence of a cognate anti-sigma factor, addressing how the activity of RpoE7 is regulated by ß-lactams will unravel new mechanisms of regulation of ß-lactam resistance in bacteria. IMPORTANCE Antimicrobial resistance is a global health problem that requires a better understanding of the mechanisms that bacteria use to resist antibiotics. Bacteria inhabiting the plant rhizosphere are a potential source of antibiotic resistance, but their mechanisms controlling antibiotic resistance are poorly understood. A. baldaniorum Sp245 is a rhizobacterium that is known for its characteristic resistance to ampicillin. Here, we show that an AmpC-type ß-lactamase and a lytic transglycosylase mediate resistance to ampicillin in A. baldaniorum Sp245. While the gene encoding lytic transglycosylase is positively regulated by an ECF σ-factor (RpoE7), a cascade of RpoE7 and RpoH3 σ factors negatively regulates the expression of ß-lactamase. This is the first evidence showing involvement of a regulatory cascade of σ factors in the regulation of ampicillin resistance in a rhizobacterium.

A Rare Gingival Lesion in Children: Fibroepithelial Hyperplasia.

Aim and objective: This case report aims to describe the management of a case of rare gingival lesion in a young pediatric patient. Background: An increase in the size of the gingival tissue is known as gingival hyperplasia. This can cause esthetic as well as functional problems, and interfere with normal functions like mastication and speech. A histological form of fibroma, fibroepithelial hyperplasia is a proliferative fibrous lesion of the gingival tissue. These lesions can be caused by trauma or persistent irritation, or they can develop from the periodontal, periodontal ligament, or periosteum cells. Case description: This paper discusses a situation in which the parents of a 4-year-old girl presented to the department with a major complaint of swelling in the upper front tooth region, who was diagnosed with fibroepithelial hyperplasia with the help of a biopsy and histologic evaluation. Conclusion: In this case surgical excision was performed under local anesthesia with no postoperative complications, and a 2-year follow-up was made with a positive outcome. Clinical significance: When these type of gingival lesions are present, they should be investigated and diagnosed properly. They should be managed as soon as possible without causing any further complications to permanent dentition. How to cite this article: Niranjan B, Shashikiran ND, Dubey A, et al. A Rare Gingival Lesion in Children: Fibroepithelial Hyperplasia. Int J Clin Pediatr Dent 2022;15(4):468-471.

Role of a fasciclin domain protein in photooxidative stress and flocculation in Azospirillum brasilense Sp7.

Fasciclin domain proteins (FDP) are found in all domains of life, but their biological role and regulation are not clearly understood. While studying the proteome of a mutant (Car1) of Azospirillum brasilense Sp7 with a Tn5 insertion in the gene encoding an anti-sigma factor (ChrR1), we found that FDP was maximally expressed. To study the biological role of this FDP, we inactivated fdp in A. brasilense Sp7 and in its Car1 mutant, which rendered them sensitive to methylene blue (MB) and toluidine blue (TB) in the presence of light. The transcription of fdp was also strongly upregulated by an ECF sigma factor (RpoE1) and photooxidative stress. The fdp null mutants of A. brasilense Sp7 and its Car1 mutant produced relatively fewer carotenoids and showed reduced flocculation. The reduced ability of fdp null mutants to flocculate was partly due to their reduced ability to produce carotenoids as inhibition of carotenoid synthesis by diphenylamine reduced their flocculation ability by 15-20%. Hence, FDP plays an important role in protecting A. brasilense Sp7 against photo-oxidative stress by supporting carotenoid accumulation and cell aggregation.