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OBJECTIVES: The aim of this study was to explore inflammation of soft tissue around the upper third molar as a prevalent cause of limited mouth opening, identify the clinical and radiographic features, and summarize the therapeutic effectiveness of tooth extraction. MATERIALS AND METHODS: A retrospective analysis of data from 264 patients with limited mouth opening over the last five years was performed. RESULTS: Among the 264 patients, 24 (9.1%) had inflammation of the soft tissue around the upper third molar, which was the second most common cause of limited mouth opening. Twenty-one of the twenty-four affected patients, with an average mouth opening of 19.1 ± 7.6 mm, underwent upper third molar extraction. Gingival tenderness around the upper third molar or maxillary tuberosity mucosa was a characteristic clinical manifestation (p < 0.05). The characteristic features on maxillofacial CT included soft tissue swelling around the upper third molar and gap narrowing between the maxillary nodules and the mandibular ascending branch. Post extraction, the average mouth opening increased to 31.4 ± 4.9 mm (p < 0.05), and follow-up CT demonstrated regression of the inflammatory soft tissue around the upper third molar. CONCLUSIONS: Inflammation of soft tissue around the upper third molar is a common cause of limited mouth opening. Symptoms of pain associated with the upper third molar and distinctive findings on enhanced maxillofacial CT scans are crucial for diagnosis. Upper third molar extraction yields favorable therapeutic outcomes. CLINICAL RELEVANCE: Inflammation of the soft tissue around the maxillary third molar commonly causes limited mouth opening, but this phenomenon has long been overlooked. Clarifying this etiology can reduce the number of misdiagnosed patients with restricted mouth opening and enable more efficient treatment for patients.
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Dente Serotino , Extração Dentária , Humanos , Dente Serotino/cirurgia , Dente Serotino/diagnóstico por imagem , Feminino , Masculino , Estudos Retrospectivos , Adulto , Pessoa de Meia-Idade , Tomografia Computadorizada por Raios X , Inflamação , AdolescenteRESUMO
Quantum mechanical second order Møller-Plesset (MP2) perturbation theory and density functional theory (DFT) Becke, 3-parameter, Lee-Yang-Parr (B3LYP) and Minnesota 2006 local functional (M06L) calculations were performed to optimize structure of nirmatrelvir and compute the Merz-Kollman electrostatic potential (MK ESP), natural population analysis (NPA), Hirshfeld, charge model 5 (CM5), and mulliken partial charges. The mulliken partial charge distribution of nirmatrelvir exhibits a poor correlation with the MK ESP charges in MP2, B3LYP, and M06L calculations respectively. The NPA, Hirshfeld, and CM5 partial charge scheme of nirmatrelvir indicate a reasonable correlation with MK ESP charge assignments in B3LYP and M06L calculations. The above correlations were not improved by the inclusion of implicit solvation model. The MK ESP and CM5 partial charges show a strong correlation between the results of MP2 and two DFT methods. The three optimized structures present a certain degree of differences from the crystal bioactive conformation of nirmatrelvir, suggesting the nirmatrelvir-enzyme complex is formed in the induced-fit model. The Reactivity of warhead electrophilic nitrile is justified by the relatively weaker strength of π bonds in the MP2 calculations. The nirmatrelvir hydrogen bond acceptors consistently show strong delocalization of lone pair electrons in three calculations, whereas hydrogen bond donors are found to have high polarization on the heavy nitrogen atoms in MP2 computations. This work helps to parametrize the force field of nirmatrelvir and improve accuracy of molecular docking and rational inhibitor design.
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Fruit shape is an important quality and yield trait in melon (Cucumis melo). Although some quantitative trait loci for fruit shape have been reported in in this species, the genes responsible and the underlying mechanisms remain poorly understood. Here, we identified and characterized a gene controlling fruit shape from two melon inbred lines, B8 with long-horn fruit and HP22 with flat-round fruit. Genetic analysis suggested that the shape was controlled by a single and incompletely dominant locus, which we designate as CmFSI8/CmOFP13. This gene was finely mapped to a 53.7-kb interval on chromosome 8 based on bulked-segregant analysis sequencing and map-based cloning strategies. CmFSI8/CmOFP13 encodes an OVATE family protein (OFP) and is orthologous to AtOFP1 and SlOFP20. The transcription level of CmFSI8/CmOFP13 in the ovary of HP22 was significantly higher than that in B8, and sequence analysis showed that a 12.5-kb genomic variation with a retrotransposon insertion identified in the promoter was responsible for elevating the expression, and this ultimately caused the differences in fruit shape. Ectopic overexpression of CmFSI8/CmOFP13 in Arabidopsis led to multiple phenotypic changes, including kidney-shaped leaves and shortened siliques. Taken together, our results demonstrate the involvement of an OFP in regulating fruit shape in melon, and our improved understanding of the molecular mechanisms will enable us to better manipulate fruit shape in breeding.
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Cucumis melo , Cucurbitaceae , Mapeamento Cromossômico , Cucumis melo/genética , Cucurbitaceae/genética , Frutas/genética , Genes de Plantas , Melhoramento VegetalRESUMO
The injury of Schwann cells is an important pathological feature of peripheral neuropathy. However, the explicit molecular mechanism and blocking method remains to be explored. In this study, we identified an pivotal executor of necroptosis-RIPK1, performed an unique function in response to oxidative stress-induced injury in Rat Schwann cells. We found that after oxidative stress-simulation by H2O2, RIPK1 was activated independent of genetic up-regulation, but through the post-translational modification, including its protein levels, phosphorylation of Serine 166 and Serine 321 sites and its general ubiquitination levels. Under a confocal microscopy, we found that RIPK1 was significantly accumulated into the mitochondria. And the phosphorylation, ubiquitination levels were also elevated in mitochondrial RIPK1, as indicated by immunoprecipitation. Through the administration of N-Acetyl-L-cysteine (NAC), a ROS inhibitor, we found that the phosphorylation, ubiquitination and mitochondrial location of RIPK1 was significantly suppressed. While administration of Necrostatin-1 (Nec-1) failed to influence the levels of ROS and mitochondrial membrane potential, revealing that RIPK1 served as the down-stream regulators of ROS. Lastly, pharmacological inhibition of RIPK1 by Nec-1 attenuated the levels of necroptosis, increased proliferation, as indicated by Annexin V/PI evaluation, CCK-8 detection, TEM scanning and EdU staining. Our results indicate a previous un-recognized post-translational change of RIPK1 in response to oxidative stress in Schwann cells.
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Peróxido de Hidrogênio , Necroptose , Ratos , Animais , Espécies Reativas de Oxigênio/metabolismo , Peróxido de Hidrogênio/metabolismo , Mitocôndrias/metabolismo , Estresse Oxidativo , Células de Schwann , Proliferação de Células , Serina/metabolismoRESUMO
Silica aerogels, which are constructed with silica nanoparticles and numerous nanoscale pores, have many outstanding attributes, but they are usually brittle and hydrophilic. For the construction of a robust aerogel, the novel polyhedral oligomeric silsesquioxane (POSS) was introduced to prepare a series of aerogels possessing particles covered with elastic cushion to improve the mechanical property. The multialkoxy POSS, which possessed stiff Si-O-Si nanocages and flexible alkyl chains, was synthesized via thiol-ene click chemistry. After a facile and efficient approach, a partially ordered structure of SiO2 nanoparticles and organic elastic cushion would form spontaneously within the aerogels. With the POSS as the only precursor, several outstanding attributes were achieved in a single aerogel such as high specific surface area (SSA), high compression strength, high compression modulus, and noticeable compression flexibility. Meanwhile, the aerogel was superhydrophobic of which the contact angle (CA) was higher than 153°. Moreover, the potential application of oil-water separation is also presented.
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An information system for epidemiological investigation on parasitic diseases was developed. The foreground of this system was realized by using C# programming language, and the ACCESS database was used to implement the data management. The system was improved by continuous field application, and has been updated from version 1.0 to 3.0. The average treatment time, logic error rate, rate of sample loss, and post-processing error rate have now been reduced by 88.0%, 100%, 98.1%, and 100%, respectively (P<0.01). This system can reduce the human error and change the field investigation into effective and high-quality pattern.
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Doenças Parasitárias/epidemiologia , Apresentação de Dados , HumanosRESUMO
Repair strategies for injured peripheral nerve have achieved great progresses in recent years. However, the clinical outcomes remain unsatisfactory. Recent studies have found that exosomes secreted by dental pulp stem cells (DPSC-exos) have great potential for applications in nerve repair. In this study, we evaluated the effects of human DPSC-exos on improving peripheral nerve regeneration. Initially, we established a coculture system between DPSCs and Schwann cells (SCs) in vitro to assess the effect of DPSC-exos on the activity of embryonic dorsal root ganglion neurons (DRGs) growth in SCs. We extracted and labeled human DPSC-exos, which were subsequently utilized in uptake experiments in DRGs and SCs. Subsequently, we established a rat sciatic nerve injury model to evaluate the therapeutic potential of DPSC-exos in repairing sciatic nerve damage. Our findings revealed that DPSC-exos significantly promoted neurite elongation by enhancing the proliferation, migration, and secretion of neurotrophic factors by SCs. In vivo, DPSC-exos administration significantly improved the walking behavior, axon regeneration, and myelination in rats with sciatic nerve injuries. Our study underscores the vast potential of DPSC-exos as a therapeutic tool for tissue-engineered nerve construction.
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Exossomos , Regeneração Nervosa , Ratos , Humanos , Animais , Regeneração Nervosa/fisiologia , Ratos Sprague-Dawley , Axônios , Polpa Dentária , Nervo Isquiático/fisiologia , Células-Tronco , Células de SchwannRESUMO
The prognosis of peripheral nerve injury (PNI) is usually poor, and currently, there is no effective treatment for PNI. Studies have shown that exosomes derived from mesenchymal stem cells could promote nerve regeneration by optimizing the function of endogenous Schwann cells (SCs), while the mechanism is unclear. Autophagy, a highly conserved intracellular catabolic process responsible for maintaining cellular homeostasis, has been proved to be involved in the regulation of nerve repair after injury. We explored the effect of exosomes derived from dental pulp stem cells (DPSC-Exos) on the regeneration of myelin sheath in rats with sciatic nerve injury (SNI). In vitro and in vivo experiments were performed to clarify whether the effect of DPSC-Exos is associated with autophagy of SCs and to reveal the mechanism at the molecular level. Our results showed that the SCs of SNI rats exhibited the obvious autophagic characteristics, and the increase of P53 expression was an internal factor of autophagy. Our mechanism research indicated that DPSC-Exos could deliver miR-122-5p from DPSCs into SCs and suppressed the rapamycin (RAPA)-induced autophagy in SCs by inhibiting P53 expression. Rescue experiments showed that both the use of GW4869 and overexpression of exogenous P53 in SCs could reverse the inhibitory effect of DPSCs on the autophagy in SCs from co-culture system. In short, our study indicated that DPSC-Exos could promote the regeneration of the myelin sheath through suppressing the autophagy in SCs caused by PNI via miR-122-5p/P53 pathway; this provides researchers with another option for precise repair of PNI.
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Autofagia , Polpa Dentária , Exossomos , Bainha de Mielina , Regeneração Nervosa , Ratos Sprague-Dawley , Células de Schwann , Nervo Isquiático , Células-Tronco , Animais , Exossomos/metabolismo , Exossomos/transplante , Polpa Dentária/citologia , Bainha de Mielina/metabolismo , Regeneração Nervosa/fisiologia , Autofagia/fisiologia , Células-Tronco/metabolismo , Nervo Isquiático/lesões , Nervo Isquiático/patologia , Células de Schwann/metabolismo , Masculino , Ratos , MicroRNAs/metabolismo , MicroRNAs/genética , Proteína Supressora de Tumor p53/metabolismo , Traumatismos dos Nervos Periféricos/terapia , Traumatismos dos Nervos Periféricos/metabolismo , Traumatismos dos Nervos Periféricos/patologia , Compostos de Anilina , Compostos de BenzilidenoRESUMO
BACKGROUND: Trigeminal neuralgia (TN) is the most common neuropathic disorder in the maxillofacial region. The etiology and pathogenesis of TN have not been clearly determined to date, although there are many hypotheses. OBJECTIVE: The goal of this study was to investigate the interactions between different types of cells in TN, particularly the impact and intrinsic mechanism of demyelination on the trigeminal ganglion, and to identify new important target genes and regulatory pathways in TN. METHODS: TN rat models were prepared by trigeminal root compression, and trigeminal nerve tissues were isolated for spatial transcriptome sequencing. The gene expression matrix was reduced dimensionally by PCA and presented by UMAP. Gene function annotation was analyzed by Metascape. The progression of certain clusters and the developmental pseudotime were analyzed using the Monocle package. Modules of the gene coexpression network between different groups were analyzed based on weighted gene coexpression network analysis and assigned AddModuleScore values. The intercellular communication of genes in these networks via ligand-receptor interactions was analyzed using CellPhoneDB analysis. RESULTS: The results suggested that the trigeminal ganglion could affect Schwann cell demyelination and remyelination responses through many ligand-receptor interactions, while the effect of Schwann cells on the trigeminal ganglion was much weaker. Additionally, ferroptosis may be involved in the demyelination of Schwann cells. CONCLUSIONS: This study provides spatial transcriptomics sequencing data on TN, reveals new markers, and redefines the relationship between the ganglion and myelin sheath, providing a theoretical basis and supporting data for future mechanistic research and drug development.
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Doenças Desmielinizantes , Neuralgia do Trigêmeo , Ratos , Animais , Neuralgia do Trigêmeo/genética , Ligantes , Transcriptoma , Nervo Trigêmeo , Doenças Desmielinizantes/complicações , Doenças Desmielinizantes/metabolismo , Doenças Desmielinizantes/patologiaRESUMO
PURPOSES: Transcriptomics-based analysis of key transcriptional molecules in the pathogenesis of trigeminal neuropathic pain was conducted to screen key molecules in the pathogenesis of trigeminal neuralgia. METHODS: Rat trigeminal nerve pathological pain model, namely chronic constriction injury of distal infraorbital nerve (IoN-CCI), was constructed and animal behaviors postsurgery were observed and analyzed. Trigeminal ganglia were collected for RNA-seq transcriptomics analysis. StringTie was used to annotate and quantify genome expression. DESeq2 was applied to compare between groups with P value less than 0.05 and fold change greater than 2 times and less than 0.5 times to screen differential genes, and display them with volcano graphs and cluster graphs. ClusterProfiler software was used to perform GO function enrichment analysis of differential genes. RESULTS: On the fifth postoperative day (POD5), the rat's face-grooming behavior increased to a peak; on the seventh postoperative day (POD7), the von-frey value dropped to the lowest value, indicating that the mechanical pain threshold of rats was significantly decreased. RNA-seq analysis of IoN-CCI rat ganglia found that the significantly up-regulated signaling pathways included B cell receptor signaling pathway, cell adhesion, complement and coagulation cascade pathways; significantly down-regulated pathways were related to systemic lupus erythematosus. Multiple genes among Cacna1s, Cox8b, My1, Ckm, Mylpf, Myoz1, Tnnc2 were involved in mediating the occurrence of trigeminal neuralgia. CONCLUSIONS: B cell receptor signaling pathway, cell adhesion, complement and coagulation cascade pathways, neuroimmune pathways are closely related to the occurrence of trigeminal neuralgia. The interaction of multiple genes among Cacna1s, Cox8b, My11, Ckm, Mylpf, Myoz1, Tnnc2 leads to the occurrence of trigeminal neuralgia.
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Nervo Trigêmeo , Neuralgia do Trigêmeo , Animais , Ratos , Neuralgia do Trigêmeo/genética , Nervo Trigêmeo/patologia , Gânglio Trigeminal , RNA-Seq , Modelos Animais de DoençasRESUMO
Intermolecular interaction between key residue N501 of the epitope on SARS-CoV-2 RBD and screening antibody B38 was studied using the QM/MM and QM approach. The QM/MM optimized geometry shows that angle X-H---Y is 165° for O-H---O between mAb light chain S30 and RBD N501. High level MP2 calculations indicated the interaction between RBD N501 and S30 of B38 Fab light chain provide a relatively strong attractive force of - 3.32 kcal/mol, whereas the hydrogen bond between RBD Q498 and S30 was quantified as 0.10 kcal/mol. The decrease in ESP partial charge on hydrogen atom of hydroxyl group on S30 drops from 0.38 a.u. to 0.31 a.u., exhibiting the sharing of 0.07 a.u. from the lone pair electron oxygen of N501 due to hydrogen bond formation. The NBO occupancy of hydrogen atom also decreases from 25.79 % to 22.93 % in the hydroxyl H-O NBO bond of S30. However, the minor change of NBO hybridization of hydroxyl oxygen of S30 from sp3.00 to sp3.05 implies the rigidity of hydrogen bond tetrahedral geometry in the relative dynamic protein complex. The O-H---O angle is 165° which is close but not exactly linear. The structural requirement for sp3 hybridization of oxygen for hydroxyl group on S30 and dimension of protein likely prevent O-H---O from adopting linear geometry. The hydrogen bond strengths were also calculated using a variety of DFT methods, and the result of - 3.33 kcal/mol from the M06L method is the closest to that of the MP2 calculation. Results of this work may aid in the COVID-19 vaccine and drug screening.
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COVID-19 , SARS-CoV-2 , Humanos , Vacinas contra COVID-19 , Oxigênio , Hidrogênio , Ligação ProteicaRESUMO
Introduction: Selenium is a critical trace element with antioxidant activities that has been related to the preservation of kidney function. Few studies, however, have looked at the effects of excess selenium on kidneys. The purpose of the present study was performed to investigate the relationship between dietary selenium intake and the prevalence of microalbuminuria in American adults with obesity. Methods: A total of 8,547 participants with obesity in the National Health and Nutrition Examination Survey (NHANES) with the age of 19 years or older were included in the present study. Multivariable regression and subgroup analyses were performed to examine the association between dietary selenium and microalbuminuria in the two genders, separately. A selenium intake above the median was defined as high selenium intake. Results: Dietary selenium intake was significantly higher in men compared to women (139.49 µg/day vs. 101.06 µg/day; P < 0.0001). Among female participants, the prevalence of microalbuminuria was significantly higher in participants with a high selenium intake compared with those without a high selenium intake (13.82 vs. 9.96%; P = 0.008), whereas this difference did not exist in male participants (10.79 vs. 11.97%; P = 0.40). Dietary selenium is not significantly correlated with microalbuminuria (P = 0.68) in the male population, whereas each 1 µg/day of increase in selenium consumption was independently associated with a 6h higher risk of microalbuminuria (OR = 1.006; 95% CI, 1.001-1.011, P = 0.01) in females. Conclusion: According to our research, excessive selenium consumption is positively correlated with microalbuminuria in females with obesity, but not in males with obesity.
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OBJECTIVE: To evaluate the field application of IHA and ELISA for schistosomiasis japonica detection at low transmission status. METHODS: 728 and 799 persons were examined by Kato-Katz's method, IHA and ELISA for schistosomiasis in an endemic village in the year of 2008 and 2010, respectively. The results of IHA and ELISA was evaluated in comparison to that of Kato-Katz (27 slides with 3 stool specimens) used as gold standard. RESULTS: The positive rate of Kato-Katz's method, IHA and ELISA were 10.3% (75/728), 40.0% (291/728) and 40.1% (292/728) in 2008, and 3.8% (30/799), 31.5% (252/799) and 40.1% (320/799) in 2010 respectively, in which significant difference was observed for the result between Kato-katz's method (chi2 = 26.92, P < 0.05) and IHA (chi2 = 11.82, P < 0.05). The consistency between the result of antibody detection and that of Kato-Katz's method was poor, lower than 0.2 (P < 0.01). If routine screening diagnosis mode was adopted, namely, population screened with IHA or ELISA first and confirmed with Kato-Katz's method, correlation analysis showed that the positive rate of Kato-Katz's method increased with the number of stool specimens and slides (rIHA2008 = 0.922, rELISA2008 = 0.908, rIHA2010 = 0.749, rELISA = 0.798; P < 0.05) . Those with egg positive but missed by IHA or ELISA mainly were cases with low infection intensity. When EPG < or = 40, the rate of detection ranged from 66.1% (39/59) to 87.0% (20/23) with IHA, and 62.7% (37/59) to 100% (23/23) with ELISA. When EPG > 40, however, all cases could be detected with ELISA, but some missed with IHA. CONCLUSION: In low transmission areas, the determination of target population for chemotherapy should be based on the examination of nine slides per stool specimen by Kato-Katz's method after serological screening.
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Ensaio de Imunoadsorção Enzimática/métodos , Testes de Hemaglutinação/métodos , Schistosoma japonicum/imunologia , Esquistossomose Japônica/diagnóstico , Esquistossomose Japônica/imunologia , Adolescente , Adulto , Idoso , Animais , Criança , Pré-Escolar , China/epidemiologia , Humanos , Masculino , Pessoa de Meia-Idade , Contagem de Ovos de Parasitas , Esquistossomose Japônica/epidemiologia , Adulto JovemRESUMO
Trigeminal neuralgia (TN) is a chronic neuropathic pain disorder characterized by spontaneous and elicited paroxysms of electric-shock-like or stabbing pain in a region of the face. The epigenetic regulation of TN is still obscure. In current study, a rat TN model subject to carbamazepine (CBZ) treatment was established, and transcriptome- and genome-scale profiling of H3K9ac and HDAC3 was performed by RNA-seq and ChIP-seq. We observed that H3K9ac levels in the trigeminal ganglion were lower in the TN rats compared with those in the control, and CBZ treatment led to recovery of H3K9ac levels. Further, we found that HDAC3 was overactivated, which interfered with H3K9 acetylation due to higher phosphorylation in TN compared with that in the control. Finally, the phosphokinase leucine-rich repeat kinase 2 (LRRK2) was demonstrated to contribute to HDAC3 activity via the MAPK signaling pathway. Taken together, we identified a regulatory mechanism in which the phosphate groups transferred from activated ERK and LRRK2 to HDAC3 caused genome-scale deacetylation at H3K9 and resulted in the silencing of a large number of genes in TN. The kinases or important enzymes within this regulatory axis may represent important targets for TN therapy and prevention.
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Neuralgia do Trigêmeo , Acetilação , Animais , Epigênese Genética , Histonas/metabolismo , Lisina/metabolismo , Ratos , Gânglio Trigeminal/metabolismo , Neuralgia do Trigêmeo/genética , Neuralgia do Trigêmeo/metabolismoRESUMO
Background: Balloon compression (BC) is a simple and effective operation to treat trigeminal neuralgia (TN). The most difficult procedure in BC is related to fast and accurate foramen ovale (FO) insertion. In this study, we introduced a new method incorporating a personalized tooth-supported digital guide plate to reduce patient trauma, improve the accuracy and the success rate of insertion, and reduce surgeons' radiation exposure. Methods: In total, 15 TN patients aged 55-70 years were recruited between January 2019 and November 2020 and retrospectively analyzed. Before the operation, based on Mimics 3D reconstruction and the modeling of patients' maxillary teeth, personalized tooth-supported digital guide plates were designed and 3D printed. All operational procedures were simulated. Then, all patients underwent BC with a personalized tooth-supported digital guide plate. Results: In the study, guide plate insertion was completed within 60 seconds for all patients. Puncturing time was limited to 5 seconds. Successful insertion into the FO was achieved in 1 attempt for all 15 participants. No patients required more than 3 postinsertion adjustments to obtain a pear-shaped balloon. There were no postoperative complications, such as cerebrospinal fluid leakage, intracranial infection, or visual acuity change. The trigger points, attack frequency per day, attack duration, and Barrow Neurological Institute (BNI) pain intensity scores of all 15 participants were significantly improved postoperation. The visual analog scale (VAS) score significantly decreased postoperation compared with that obtained preoperation (all P<0.001) and gradually decreased with the extension of follow-up time. Conclusions: By applying a personalized tooth-supported digital guide plate, we can significantly avoid the use of an incision outside the mouth, decrease the difficulty of FO insertion, and reduce patient trauma. The operation is more suitable for novice surgeons and protects surgeons from the harm of radiation. This new technology may improve the success rate and accuracy of FO insertion, although a multicenter, large sample, randomized controlled trial is needed.
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In order to investigate the effects of Burkholderia sp. Y4 on rice seedlings under cadmium (Cd) stress, seed germination and vermiculite culture experiments were conducted using low Cd-accumulation xiangzaoxian 24 (X24) and high Cd-accumulation Tyou 705 (T705) varieties. The effects of Burkholderia sp. Y4 on rice growth, oxidative damage caused by Cd, and Cd accumulation were studied. Additionally, the Cd2+ flux rates in the elongation zone of rice roots under Burkholderia sp. Y4 application were detected using non-invasive micro-test technology. Burkholderia sp. Y4 alleviated the inhibition effect of Cd on rice seed germination by 13.8%. After inoculation with Burkholderia sp. Y4 for 7 d, the length of rice roots and buds increased by 83.3% and 12.2%, and their dry weight increased by 56.8% and 12.5%, respectively; those in the 10 d Y4 inoculation group increased by 28.6% and 20.0% in length and by 113.2% and 46.0% in dry weight, respectively. Burkholderia sp. Y4 inoculation also alleviated rice oxidative stress damage caused by Cd. The application of strain Y4 significantly reduced the content of the oxidative damage product malondialdehyde (MDA) in the shoots and roots of rice seedlings by 21.5% and 16.9%, respectively. Under Burkholderia sp. Y4 inoculation, the significant changes in antioxidant enzyme SOD and CAT activities caused by Cd stress disappeared in rice roots; those in shoots also decreased from 176.9% and 74.8% to 53.3% and 21.5%, respectively. Conversely, Burkholderia sp. Y4 inhibited Cd uptake by rice seedlings with different genotypes, including the low Cd-accumulation variety X24 and high Cd-accumulation variety T705. The root application of strain Y4 significantly reduced Cd accumulation in the shoots and roots of rice seedlings by 79.2% and 62.7% in T705 and by 57.3% and 24.1% in X24, respectively. The Cd2+ flux rate of high Cd-accumulation variety T705 was significantly higher than that of low Cd-accumulation variety X24. Under Burkholderia sp. Y4 inoculation, the yellow membrane was formed on the root surface of rice seedlings, and the Cd2+ flux rate in the elongation zone of T705 and X24 roots decreased by 36.0% and 35.0% in 3-day-old seedlings, as well as by 44.6% and 24.9% in 10-day-old seedlings, respectively. In conclusion, Burkholderia sp. Y4 inoculation inhibited the toxic effects of Cd on rice seedling growth through alleviating oxidative stress and damage caused by Cd. Furthermore, the root application of Burkholderia sp. Y4 effectively decreased the Cd2+ flux rate in the elongation zone of roots to inhibit the Cd uptake and accumulation in roots and shoots of rice seedlings. This study provides theoretical basis and data support for the application of Burkholderia sp. Y4 as a Cd-reducing and growth-promoting agent for rice in contaminated farmland.
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Burkholderia , Oryza , Poluentes do Solo , Antioxidantes , Burkholderia/fisiologia , Cádmio/análise , Cádmio/toxicidade , Raízes de Plantas/química , Plântula , Poluentes do Solo/toxicidadeRESUMO
The role of the nonbonded CH···π interaction in the hydrogen abstraction from glycerol by the coenzyme B(12)-independent glycerol dehydratase (GDH) was examined using the QM/MM (ONIOM), MP2, and CCSD(T) methods. The studied CH···π interaction included the hydrogen atom of the -C(2)H(OH)- group of the glycerol substrate and the tyrosine-339 residue of the dehydratase. A contribution of this interaction to the stabilization of the transition state for the transfer of a hydrogen atom from the adjacent terminal C(1)H(2)(OH) group to cysteine 433 was determined by ab initio HF, MP2, and CCSD(T) calculations with the aug-cc-pvDZ basis set for the corresponding methane/benzene, methanol/phenol, and glycerol radical/phenol subsystems. The calculated CH···π distance, defined as the distance between the H atom and the center of the phenol ring, shortened from 2.62 to 2.52 Å upon going from the ground- to the transition-state of the GDH-catalyzed reaction. However, this shortening was not accompanied by the expected lowering of the CH···π interaction free energy. Instead, this interaction remained weak (about -1 kcal/mol) along the entire reaction coordinate. Additionally, the mutual orientation of the CH group and the phenol ring did not change significantly during the reaction. These results suggest that the phenol group of the tyrosine-339 does not contribute to lowering the activation barrier in the enzyme, but do not exclude the possibility that tyrosine 339 facilitates proper orientation of glycerol for the electrostatic catalysis, or inhibits side-reactions of the reactive glycerol radical intermediate.
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Hidroliases/metabolismo , Hidrogênio/metabolismo , Biocatálise , Hidroliases/química , Hidrogênio/química , Teoria Quântica , TermodinâmicaRESUMO
To evaluate the feasibility of applying L-cysteine (L-Cys) as a foliar conditioner for Cd reduction in rice, a field experiment was conducted to investigate the concentration of Cd and mineral elements in rice after the foliar application of L-Cys. The variation in Cd distribution and morphology in key rice organs was examined to study the Cd reduction mechanisms of spraying L-Cys on rice. The results showed that foliar application of L-Cys at the rice-flowering stage significantly decreased Cd concentration in grains, in a concentration dependent manner, without inhibiting the accumulation of mineral elements Ca, Mg, K, Mn, and Zn. With a 10 mmol ·L-1 L-Cys application, Cd concentration in rice grains decreased by 59.2%, to below 0.2 mg ·kg-1, which is the maximum safety limit in China. Foliar application of L-Cys also inhibited Cd accumulation in rice vegetative organs, including rachises, first nodes, neck-panicles, flag leaves, second internodes, second nodes, second leaves, stalks, and roots (58.3%, 56.0%, 62.7%, 67.0%, 59.3%, 61.5%, 60.2%, 54.9%, and 50.3%, respectively). After transfer factor calculation, first nodes were found to be the key organ for Cd blocking in rice. The application of L-Cys increased Cd transfer from flag leaves and second internodes to first nodes (105.4% and 45.8%, respectively), but decreased Cd transfer from first nodes up to neck-panicles (27.5%). In rice first nodes, the concentrations of Cd in the inorganic, water soluble, and residue states were all lower following L-Cys application, and the proportion of residual Cd increased to 94.4%. Therefore, foliar application of L-Cys significantly inhibited Cd transport and accumulation in rice grains, by decreasing the Cd concentrations of various vegetative organs and improving Cd interception in the first nodes. This is a promising way to produce rice with lower Cd concentrations and normal mineral element concentrations in Cd-contaminated paddy fields.
Assuntos
Oryza , Poluentes do Solo , Cádmio/análise , China , Cisteína , Minerais , Solo , Poluentes do Solo/análiseRESUMO
Cadmium (Cd) pollution in paddy soil seriously endangers food safety production. To investigate the effects and microbiological mechanisms of calcium-magnesium-phosphate (CMP) fertilizer application on Cd reduction in rice, field experiments were conducted in Cd-contaminated paddy soil. Compared with conventional compound fertilizer, CMP fertilizer treatments inhibited Cd uptake through plant roots, significantly decreasing Cd content in rice grains from 0.340 to 0.062 mg/kg. Soil pH and total Ca, Mg and P contents increased after CMP fertilizer application, resulting in a further decrease in soil available Cd content from 0.246 to 0.181 mg/kg. Specific extraction analysis recorded a decrease in both available Fe content and the ratio of nitrate to ammonium nitrogen, indicating that the soil Fe-N cycle was affected by the addition of CMP fertilizer. This finding was also recorded using soil bacterial community sequencing, with CMP fertilizer promoting the progress of nitrate-dependent Fe-oxidation driven by Thiobacillus (1.60-2.83%) and subsequent dissimilatory nitrate reduction to ammonium (DNRA) driven by Ignavibacteriae (1.01-1.92%); Fe-reduction driven by Anaeromyxobacter (3.09-2.23%) was also inhibited. Our results indicate that CMP fertilizer application regulates the Fe-N coupling cycle driven by the soil microbial community to benefit remediation of Cd contaminated paddy soil.
Assuntos
Microbiota , Oryza , Poluentes do Solo , Cádmio/análise , Cádmio/toxicidade , Cálcio , Fertilizantes/análise , Ferro , Óxido de Magnésio , Nitrogênio , Fosfatos , Solo , Poluentes do Solo/análise , Poluentes do Solo/toxicidadeRESUMO
The combination of endophytes and hyperaccumulator plants can significantly improve the efficiency of heavy metal phytoremediation in contaminated soil. A plant endophyte named Herbaspirillum R-13 was isolated from rice roots in a cadmium (Cd) contaminated paddy field. This strain exhibited a strong tolerance to Cd2+ and could grow on a solid medium with a Cd2+ concentration of 300 mg·kg-1. The R-13 strain was able to produce siderophores and Indole acetic acid (IAA), through color reactions. In addition, Pikovskaya's and Ashby's solid medium tests showed that the R-13 strain had a lower capacity for dissolving phosphorus but a higher capacity for fixing nitrogen. In the pot experiment, high-throughput sequencing technology was used to track the colonization of the R-13 strain in Solanum nigrum L. roots. Three days after inoculation, the relative abundance of Herbaspirillum in the root of Solanum nigrum L. had increased by 201.88% compared to the blank control (CK) and after two inoculations, the relative abundance of Herbaspirillum in the root of Solanum nigrum L. had increased by 1182.44% compared to CK. The relative abundance of Herbaspirillum in the root of Solanum nigrum L. began to decrease significantly from 5 days after inoculation. Inoculation with 20 mL·pot-1 of R-13 fermentation broth resulted in no significant effects on the Cd content of roots, stems, leaves, or fruits of S. nigrum L. With 40 mL·pot-1 of fermentation broth, the Cd content of vegetative organs and fruits was significantly increased. When it reached 200 mL·pot-1, the Cd content of vegetative organs was the highest, with Cd concentrations in the roots, stems, leaves, and fruits increasing by 84.42%, 43.67%, 64.06%, and 20.29%, respectively. In conclusion, root inoculation with endophytic Herbaspirillum R-13 can significantly increase the relative content of Herbaspirillum in the root system and enhance Cd absorption of S. nigrum L. Therefore, this strain has excellent prospects for application in the phytoremediation of soil contaminated with Cd.