Efficacy and Safety of High-Viscosity Bone Cement in Percutaneous Vertebroplasty for Kummell's Disease.

Background: To analyze and evaluate the clinical outcomes of using high-viscosity bone cement compared to low-viscosity bone cement in percutaneous vertebroplasty (PVP) for treatment of Kummell's disease. Methods: From July 2017 to July 2019, 68 Kummell's disease patients who underwent PVP were chosen and separated into 2 groups: H group (n = 34), were treated with high-viscosity bone cement and L group (n = 34), treated with low-viscosity bone cement during treatment. The operation time, number of fluoroscopy tests done, and amount of bone cement perfusion were recorded for both groups. Clinical outcomes were compared, by measuring their Visual Analog Scale (VAS), Oswestry Disability Index (ODI), Kyphosis Cobb's angle, vertebral height compression rate, and other complications. Results: High-viscosity group showed less operation time and reduced number of fluoroscopy tests than the low-viscosity group (P < 0.05). When compared to preoperative period, both groups' VAS and ODI scores were significantly reduced at 1 day and 1 year postoperatively (P < 0.05). The vertebral height compression rate and Cobb's angle were significantly lower (P < 0.05) in both groups after surgery compared with those before surgery (P < 0.05). The cement leakage rate in group H was 26.5%, which was significantly lower than that in group L, which was 61.8% (P < 0.05). Conclusions: High-viscosity and low-viscosity bone cement in PVP have similar clinical efficacy in reducing pain in patients during the treatment, but in contrast, high-viscosity bone cement shortens the operative time, reduces number of fluoroscopy views and vertebral cement leakage and improves surgical safety.

The Relationship Between Endplate Defect Scores and Lumbar Sagittal Translation Stability in Lumbar Spondylolisthesis Patients.

BACKGROUND: Lumbar instability and endplate defects are commonly seen in patients with spondylolisthesis. However, little is known about associations between segmental stability and endplate defects. The present study explored associations between stability-related radiographic parameters and endplate defect scores and assessed whether endplate defect scores can predict lumbar stability in lumbar spondylolisthesis. METHODS: Neutral, flexion, and extension radiographs of 159 patients with monosegmental lumbar spondylolisthesis were analyzed. Radiographic parameters included average intervertebral disc height (IDH), slip distance, sagittal translation (ST) and sagittal angulation (SA). Correlation analysis and linear regression analysis were used to explore associations between endplate defect scores and radiographic parameters. Logistic regression analysis was used to assess associations between endplate defect scores and ST stability. Receiver-operating characteristic curve (ROC) analysis was used to evaluate the value of the endplate defect score in predicting ST stability. RESULTS: A total of 11.9% of patients had ST ≥ 4 mm, and 30% of patients had SA ≥ 10°. Endplate defect scores were negatively correlated with ST and IDH and positively correlated with slip distance in isthmic spondylolisthesis but not in degenerative spondylolisthesis. In multiple regression analysis, endplate defect scores were significantly associated with ST, slip distance, IDH, and disc degeneration. ST instability was associated with endplate defect scores in isthmic spondylolisthesis (OR=0.460, P = 0.010). The AUCs for using the endplate defect score to evaluate ST stability in overall patients and isthmic spondylolisthesis patients were 0.672 and 0.774, respectively. The optimal threshold of the endplate defect score constructed by the Youden index was 7.5 for predicting ST stability. CONCLUSIONS: Endplate defect scores increase with a reduction in IDH, progression of slippage and a decrease in ST in isthmic spondylolisthesis but not in degenerative spondylolisthesis. ST instability was associated with endplate defect scores in isthmic spondylolisthesis, and endplate defect scores could be used to reflect lumbar stability at the slippage segment.

Causal associations between modifiable risk factors and intervertebral disc degeneration.

BACKGROUND: Intervertebral disc degeneration (IVDD) is a common degenerative condition, which is thought to be a major cause of lower back pain (LBP). However, the etiology and pathophysiology of IVDD are not yet completely clear. PURPOSE: To examine potential causal effects of modifiable risk factors on IVDD. STUDY DESIGN: Bidirectional Mendelian randomization (MR) study. PATIENT SAMPLE: Genome-wide association studies (GWAS) with sample sizes between 54,358 and 766,345 participants. OUTCOME MEASURES: Outcomes included (1) modifiable risk factors associated with IVDD use in the forward MR; and (2) modifiable risk factors that were determined to have a causal association with IVDD in the reverse MR, including smoking, alcohol intake, standing height, education level, household income, sleeplessness, hypertension, hip osteoarthritis, HDL, triglycerides, apolipoprotein A-I, type 2 diabetes, fasting glucose, HbA1c, BMI and obesity trait. METHODS: We obtained genetic variants associated with 33 exposure factors from genome-wide association studies. Summary statistics for IVDD were obtained from the FinnGen consortium. The risk factors of IVDD were analyzed by inverse variance weighting method, MR-Egger method, weighted median method, MR-PRESSO method and multivariate MR Method. Reverse Mendelian randomization analysis was performed on risk factors found to be caustically associated with IVDD in the forward Mendelian randomization analysis. The heterogeneity of instrumental variables was quantified using Cochran's Q statistic. RESULTS: Genetic predisposition to smoking (OR=1.221, 95% CI: 1.068-1.396), alcohol intake (OR=1.208, 95% CI: 1.056-1.328) and standing height (OR=1.149, 95% CI: 1.072-1.231) were associated with increased risk of IVDD. In addition, education level (OR=0.573, 95%CI: 0.502-0.654)and household income (OR=0.614, 95%CI: 0.445-0.847) had a protective effect on IVDD. Sleeplessness (OR=1.799, 95%CI: 1.162-2.783), hypertension (OR=2.113, 95%CI: 1.132-3.944) and type 2 diabetes (OR=1.069, 95%CI: 1.024-1.115) are three important risk factors causally associated with the IVDD. In addition, we demonstrated that increased levels of triglycerides (OR=1.080, 95%CI:1.013-1.151), fasting glucose (OR=1.189, 95%CI:1.007-1.405), and HbA1c (OR=1.308, 95%CI:1.017-1.683) could significantly increase the odds of IVDD. Hip osteoarthritis, HDL, apolipoprotein A-I, BMI and obesity trait factors showed bidirectional causal associations with IVDD, therefore we considered the causal associations between these risk factors and IVDD to be uncertain. CONCLUSIONS: This MR study provides evidence of complex causal associations between modifiable risk factors and IVDD. It is noteworthy that metabolic disturbances appear to have a more significant effect on IVDD than biomechanical alterations, as individuals with type 2 diabetes, elevated triglycerides, fasting glucose, and elevated HbA1c are at higher risk for IVDD, and the causal association of obesity-related characteristics with IVDD incidence is unclear. These findings provide new insights into potential therapeutic and prevention strategies. Further research is needed to clarify the mechanisms of these risk factors on IVDD.

Identification of mitochondria-related key gene and association with immune cells infiltration in intervertebral disc degeneration.

Intervertebral disc (IVD) degeneration and its inflammatory microenvironment can result in discogenic pain, which has been shown to stem from the nucleus pulposus (NP). Increasing evidence suggests that mitochondrial related genes are strictly connected to cell functionality and, importantly, it can regulate cell immune activity in response to damaged associated signals. Therefore, identification of mitochondria related genes might offer new diagnostic markers and therapeutic targets for IVD degeneration. In this study, we identified key genes involved in NP tissue immune cell infiltration during IVD degeneration by bioinformatic analysis. The key modules were screened by weighted gene co-expression network analysis (WCGNA). Characteristic genes were identified by random forest analysis. Then gene set enrichment analysis (GSEA) was used to explore the signaling pathways associated with the signature genes. Subsequently, CIBERSORT was used to classify the infiltration of immune cells. Function of the hub gene was confirmed by PCR, Western blotting and ELISA. Finally, we identified MFN2 as a crucial molecule in the process of NP cell pyroptosis and NLRP3 inflammasome activation. We speculate that the increased MFN2 expression in NP tissue along with the infiltration of CD8+ T cells, NK cell and neutrophils play important roles in the pathogenesis of IVD degeneration.

Abscisic acid facilitates phosphate acquisition through the transcription factor ABA INSENSITIVE5 in Arabidopsis.

Low phosphate (LP) in soil is a common nutrient stress that severely restricts agricultural production, but the role, if any, of the major stress phytohormone abscisic acid (ABA) in plant phosphate (Pi) starvation responses remains elusive. Here, we report that LP-induced ABA accumulation promotes Pi uptake in an ABA INSENSITIVE5 (ABI5)-dependent manner in Arabidopsis thaliana. LP significantly activated plant ABA biosynthesis, metabolism, and stress responses, suggesting a role of ABA in the plant response to Pi availability. LP-induced ABA accumulation and expression of two major high-affinity phosphate transporter genes PHOSPHATE TRANSPORTER1;1/1;4 (PHT1;1/1;4) were severely impaired in a mutant lacking BETA-GLUCOSIDASE1 (BG1), which converts conjugated ABA to active ABA, and the mutant had shorter roots and less Pi content than wild-type plants under LP conditions. Moreover, a mutant of ABI5, which encodes a central transcription factor in ABA signaling, also exhibited suppressed root elongation and had reduced Pi content under LP conditions. ABI5 facilitated Pi acquisition by activating the expression of PHT1;1 by directly binding to its promoter, while overexpression of PHT1;1 completely rescued its Pi content under LP conditions. Together, our findings illustrate a molecular mechanism by which ABA positively modulates phosphate acquisition through ABI5 in the Arabidopsis response to phosphate deficiency.

Comparative analysis of the effects of OLIF and TLIF on adjacent segments after treatment of L4 degenerative lumbar spondylolisthesis.

BACKGROUND: The fusion of the lumbar spine may lead to the degeneration of the adjacent segments. In this study, the effects of OLIF and TLIF on adjacent segments after treatment of L4 degenerative lumbar spondylolisthesis (DLS) were compared and analysed. METHODS: This was a retrospective analysis of the medical records of consecutive patients treated with OLIF or TLIF for L4DLS. They were divided into the OLIF group and TLIF group based on different treatment methods. Cage height, segmental lordosis (SL), lumbar lordosis (LL), pelvic incidence (PI), pelvic tilt (PT), and sacral slope (SS) were compared between the two groups, and the postoperative biomechanical changes were analysed by establishing the disc angle (DA). The clinical outcomes were analysed by comparing the visual analogue scale (VAS), Oswestry Disability Index (ODI) and incidence of adjacent segment disease (ASDis) between the two groups. The intervertebral disc height (IDH), intervertebral foramen height (IDH), intervertebral foramen area (IFA), sliding distance (SD), and angular displacement (AD) in L3-4 and L5-S1 were compared between the two groups. The incidence of aggravated disc degeneration (ADD), the incidence of aggravated zygapophyseal joint degeneration (AJD) and the incidence of adjacent segment degeneration (ASDeg) were compared between the two groups for radiological degeneration. RESULTS: At the last follow-up, there was one case of ASDis in the OLIF group (2.78%) and two cases in the TLIF group (5.56%). At the last follow-up, compared with the preoperative values, IDH, IFH, and IFA of the adjacent segments above and below L4-5 decreased in both groups (P < 0.05); the SD and AD increased in both groups (P < 0.05). The cage height and L4-5 IDH in the OLIF group were significantly higher than those in the TLIF group (P < 0.05). SL, LL, PT, SS, and L5- S1DA were significantly improved in the OLIF group compared with the TLIF group (P < 0.05). The incidence of L3-4ASDeg in the two groups was higher than that of L5-S1. The incidence of ASDeg and the incidence of L5-S1ADD in the OLIF group were lower than those in the TLIF group, but the incidence of L5-S1AJD was higher than that in the TLIF group. CONCLUSION: L4DLS after OLIF and TLIF treatment will cause adjacent segment degeneration, and L3-4 degeneration is more obvious than L5-S1 degeneration. OLIF has more advantages in restoring lumbar sagittal balance. Compared with TLIF, OLIF can weaken the degeneration of the L5-S1 disc and increase the degeneration of the L5-S1 zygapophyseal joints.

Sorting Nexin1 negatively modulates phosphate uptake by facilitating Phosphate Transporter1;1 degradation in Arabidopsis.

High-affinity phosphate (Pi) transporters (PHTs) PHT1;1 and PHT1;4 are necessary for plant root Pi uptake especially under Pi-deficient conditions, but how their protein stability is modulated remains elusive. Here, we identified a Ttransfer DNA insertion mutant of Sorting Nexin1 (SNX1), which had more Pi content and less anthocyanin accumulation than the wild type under deficient Pi. By contrast, the snx1-2 mutant displayed higher sensitivity to exogenous arsenate in terms of seed germination and root elongation, revealing higher Pi uptake rates. Further study showed that SNX1 could co-localize and interact with PHT1;1 and PHT1;4 in vesicles and at the plasma membrane. Genetic analysis showed that increased Pi content in the snx1-2 mutant under low Pi conditions could be extensively compromised by mutating PHT1;1 in the double mutant snx1-2 pht1;1, revealing that SNX1 is epistatic to PHT1;1. In addition, SNX1 negatively controls PHT1;1 protein stability; therefore, PHT1;1 protein abundance in the plasma membrane was increased in the snx1-2 mutant compared with the wild type under either sufficient or deficient Pi. Together, our study (i) identifies SNX1 as a key modulator of the plant response to low Pi and (ii) unravels its role in the modulation of PHT1;1 protein stability, PHT1;1 accumulation at the plasma membrane, and root Pi uptake.

Clinical correlation between osteoporotic thoracolumbar vertebral compression fractures and lumbar spondylolisthesis.

PURPOSE: This study was to explore the clinical correlation between osteoporosis thoracolumbar vertebral compression fracture (thoracolumbar OVCF) and lumbar spondylolisthesis (LS). METHODS: In total, 208 patients with thoracolumbar OVCF (fracture group) and 250 elderly patients with osteoporosis (non-fracture group) were retrospectively analyzed. The incidence of LS was compared between the two groups. At the same time, 75 cases of elderly patients with osteoporosis were selected, including 25 patients with isthmic spondylolisthesis (IS group), 25 patients with degenerative spondylolisthesis (DS group), and 25 patients without LS (non-LS group). All patients underwent full-length spine anteroposterior and lateral X-ray, and the spinal pelvic imaging parameters were collected for comparison. RESULTS: The incidence of LS in the fracture group (10.1%, 21/208) was significantly higher than that in the non-fracture group (4.8%, 12/250); the difference was statistically significant (χ2 = 4.763, P = 0.029). The incidence of trauma in the fracture group (51.0%, 106/208) was significantly higher than that in the non-fracture group (13.6%, 34/250); the difference was statistically significant (χ2 = 74.673, P = 0.000). The LS (OR = 2.273, 95% CI = 1.030-5.017, P = 0.042) and trauma (OR = 6.622, 95% CI = 4.203-10.432, P = 0.000) were independently associated with thoracolumbar OVCF. There were significant differences in pelvic incidence (PI), sacral slope (SS), lumbar lordosis (LL), thoracolumbar kyphosis (TLK), and thoracic kyphosis (TK) among the IS, DS, and non-LS groups (P < 0.05). Among them, PI, SS, LL, TLK, and TK of the IS group and the DS group were significantly higher than those of the non-LS group (P < 0.05). CONCLUSIONS: Patients with LS are more likely to suffer from OVCF in the future, and LS is one of the important risk factors for secondary OVCF.

Maize PHYTOMELATONIN RECEPTOR1 functions in plant tolerance to osmotic and drought stress.

Phytomelatonin is a universal signal molecule that regulates plant growth and stress responses; however, only one receptor that can directly bind with and perceive melatonin signaling has been identified so far, namely AtPMTR1/CAND2 in Arabidopsis. Whether other plants contain a similar receptor and, if so, how it functions is still unknown. In this study, we identified a new phytomelatonin receptor in the monocot maize (Zea mays), and investigated its role in plant responses to osmotic and drought stress. Using homology searching, we identified a plasma membrane-localized protein, Zm00001eb214610/ZmPMTR1, with strong binding activity to melatonin as a potential phytomelatonin receptor in maize. Overexpressing ZmPMTR1 in Arabidopsis Col-0 promoted osmotic stress tolerance, and rescued osmotic stress sensitivity of the Arabidopsis cand2-1 mutant. Furthermore, ZmPMTR1 also largely rescued defects in melatonin-induced stomatal closure in the cand2-1 mutant, thereby reducing water loss rate and increasing tolerance to drought stress. In addition, we identified a maize mutant of ZmPMTR1, EMS4-06e2fl, with a point-mutation causing premature termination of protein translation, and found that this mutant had lower leaf temperatures, increased rate of water loss, and enhanced drought stress sensitivity. Thus, we present ZmPMTR1 as the first phytomelatonin receptor to be identified and examined in a monocot plant, and our results indicate that it plays an important function in the response of maize to drought stress.

Overexpressing the N-terminus of CATALASE2 enhances plant jasmonic acid biosynthesis and resistance to necrotrophic pathogen Botrytis cinerea B05.10.

Salicylic acid (SA) acts antagonistically to jasmonic acid (JA) in plant immunity. We previously reported that CATALASE2 (CAT2) promotes JA-biosynthetic acyl-CoA oxidase (ACX) activity to enhance plant resistance to necrotrophic Botrytis cinerea, and SA represses JA biosynthesis through inhibiting CAT2 activity, while the underlying mechanism remains to be further elucidated. Here, we report that the truncated CAT2 N-terminus (CAT2-N) interacts with and promotes ACX2/3, and CAT2-N-overexpressing plants have increased JA accumulation and enhanced resistance to B. cinerea B05.10, but compromised antagonism of SA on JA. Catalase inhibitor treatment or mutating CAT2 active amino acids abolished CAT2 H2 O2 -decomposing activity but did not affect its promotion of ACX2/3 activity via interaction. CAT2-N, a truncated protein with no catalase activity, interacted with and promoted ACX2/3. Overexpressing CAT2-N in Arabidopsis plants resulted in increased ACX activity, higher JA accumulation, and stronger resistance to B. cinerea B05.10 infection. Additionally, SA dramatically repressed JA biosynthesis and resistance to B. cinerea in the wild type but not in the CAT2-N-overexpressing plants. Together, our study reveals that CAT2-N can be utilized as an accelerator for JA biosynthesis during plant resistance to B. cinerea B05.10, and this truncated protein partly relieves SA repression of JA biosynthesis in plant defence responses.

Mutual Promotion of LAP2 and CAT2 Synergistically Regulates Plant Salt and Osmotic Stress Tolerance.

Almost all abiotic stresses induce reactive oxygen species (ROS) overaccumulation, causing oxidative damages to plant cells. Catalase (CAT) plays a vital role in plant oxidative stress tolerance by scavenging stress-induced excess H2O2; thus, the identification of factors regulating catalase function will shed light on the underlying regulatory mechanisms. Here, we identified leucine aminopeptidase 2 (LAP2) as a novel CAT2-interacting protein and showed a mutual promotion effect of the two proteins in plant stress responses. LAP2 has a physical interaction with CAT2 in plant cells. The loss-of-function mutant of LAP2, lap2-3, is hypersensitive to salt or osmotic stress with increased ROS accumulation and malondialdehyde content and decreased catalase activity. The lap2-3 mutant has less CAT2 protein levels as CAT2 protein stability is impaired in the mutant. Scavenging excess ROS by glutathione or overexpressing CAT2 in the lap2-3 mutant recovers its hypersensitive phenotype to salt or osmotic stress. Further study showed that CAT2 promotes LAP2 hydrolysis activity with leucine-4-methylcoumaryl-7-amides as a substrate in vivo and in vitro, and thus, similar to the lap2-3 mutant, the cat2-1 mutant also has lower γ-aminobutyric acid content than the wild type. Together, our study reveals mutual promotion effects of CAT2 and LAP2 in conferring plant salt and osmotic stress tolerance.

Vitamin D inhibits TNF-α induced apoptosis of human nucleus pulposus cells through regulation of NF-kB signaling pathway.

BACKGROUND: To observe the effects of vitamin D on the apoptotic human nucleus pulposus cells under tumor necrosis factor-α (TNF-α) treatment. METHODS: The gene expression data was downloaded from the NCBI Gene Expression Omnibus (GEO) database ( https://www.ncbi.nlm.nih.gov/geo/query/acc.cgi?acc=GSE34095 ). Differentially expressed genes between degenerative disc and non-degenerative disc were performed by R software. Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genome (KEGG) pathway enrichment analyses were performed using The Database for Annotation, Visualization and Integrated Discovery (DAVID). Then, the human nucleus pulposus tissue was harvested from 12 patients according to the modified Pfirrmann classification and human nucleus pulposus cells were obtained from digestion of herniated nucleus pulposus tissue. The collected nucleus pulposus cells were treated with different concentration of TNF-α, and cellular apoptosis was measured by flow cytometry. Then, human nucleus pulposus cells were divided into following groups: normal culture medium, TNF-α treated, TNF-α, and vitamin D-treated groups. Cellular apoptosis rate was quantified by flow cytometry. Protein expression of p-p65, p65, and IkBa was detected with western blot analysis. RESULTS: A total of 536 differentially expressed genes were identified through bioinformatic analysis. KEGG pathway revealed that NF-kB signaling pathway was involved in the process of disc degeneration. In the NP cell cultures, vitamin D significantly increased cell proliferation potency. Furthermore, vitamin D inhibited TNF-α induced apoptosis of human nucleus pulposus cells. Vitamin D reduced the phospho-NF-κB/p65 expression in the TNF-α-treated NP cells. CONCLUSION: Vitamin D can attenuate TNF-α-induced NP cells apoptosis through interfering with the NF-κB pathway.

CAND2/PMTR1 Is Required for Melatonin-Conferred Osmotic Stress Tolerance in Arabidopsis.

Osmotic stress severely inhibits plant growth and development, causing huge loss of crop quality and quantity worldwide. Melatonin is an important signaling molecule that generally confers plant increased tolerance to various environmental stresses, however, whether and how melatonin participates in plant osmotic stress response remain elusive. Here, we report that melatonin enhances plant osmotic stress tolerance through increasing ROS-scavenging ability, and melatonin receptor CAND2 plays a key role in melatonin-mediated plant response to osmotic stress. Upon osmotic stress treatment, the expression of melatonin biosynthetic genes including SNAT1, COMT1, and ASMT1 and the accumulation of melatonin are increased in the wild-type plants. The snat1 mutant is defective in osmotic stress-induced melatonin accumulation and thus sensitive to osmotic stress, while exogenous melatonin enhances the tolerance of the wild-type plant and rescues the sensitivity of the snat1 mutant to osmotic stress by upregulating the expression and activity of catalase and superoxide dismutase to repress H2O2 accumulation. Further study showed that the melatonin receptor mutant cand2 exhibits reduced osmotic stress tolerance with increased ROS accumulation, but exogenous melatonin cannot revert its osmotic stress phenotype. Together, our study reveals that CADN2 functions necessarily in melatonin-conferred osmotic stress tolerance by activating ROS-scavenging ability in Arabidopsis.

WDR5a functions in cadmium-inhibited root meristem growth by regulating nitric oxide accumulation in Arabidopsis.

MAIN CONCLUSION: Cadmium stress induces WDR5a expression to promote NO accumulation to repress root meristem growth via suppressing auxin transport and synthesis in Arabidopsis. Nitric oxide (NO) synthase (NOS)-like activity plays a vital role in toxic cadmium (Cd)-induced NO production and inhibition of root meristem growth, while factor(s) regulating NOS-like activity and root meristem growth in plant response to Cd has not been identified yet. Here, we report that WD40 repeat 5a (WDR5a) functions in Cd-induced NOS-like activity, NO accumulation and root meristem growth suppression. We found that wdr5a-1 mutant root has increased root meristem growth with lower NOS-like activity and NO accumulation than wild type upon Cd exposure, and exogenous NO donors sodium nitroprusside or nitrosoglutathione can restore its reduced Cd sensitivity. In addition, Cd activates WDR5a expression in roots, and overexpressing WDR5a results in increased NO accumulation and suppressed root meristem growth similar to Cd-stressed wild-type roots, while scavenging NO or inhibiting NOS-like activity significantly reverts these effects of Cd. Furthermore, WDR5a acts in Cd-repressed auxin accumulation through reducing the levels of auxin efflux carriers PIN1/3/7 and biosynthetic enzyme TAA1, and reduced sensitivity of wdr5a-1 root meristem to Cd can be partially reverted by inhibiting TAA1 activity pharmaceutically or mutating TAA1 genetically. This study identified WDR5a as a key factor modulating NO accumulation and root meristem growth in plant response to Cd.

Rufibacter hautae sp. nov., a red-pigmented bacterium from freshwater lake sediment, and proposal of Rufibacter quisquiliarum as a latter heterotypic synonym of Rufibacter ruber.

A taxonomic identification using a polyphasic approach was performed on strain NBS58-1T, which was isolated from the interfacial sediment of Taihu Lake in China. Strain NBS58-1T was Gram-stain-negative, aerobic, non-spore-forming and catalase-positive. Phylogenetic analyses based on 16S rRNA gene and three housekeeping genes (rpoB, gyrB and dnaK) sequences supported the position that strain NBS58-1T should be classified within the genus Rufibacter. The 16S rRNA gene sequence of strain NBS58-1T possessed the highest similarity to Rufibacter sediminis H-1T (96.60 %), followed by Rufibacter glacialis MDT1-10-3T (96.17 %). And the ANI value between strain NBS58-1T and R. glacialis MDT1-10-3T was 79.3 %. The respiratory quinone was menaquinone 7 (MK-7). The major cellular fatty acids comprised iso-C15 : 0 and summed feature 3. Phosphatidylethanolamine, two unidentified phospholipids and four unidentified lipids were the main polar lipids. The genomic DNA G+C content was 51.3 mol%. Based on phenotypic features and phylogenetic position, a novel species with the name Rufibacter hautae sp. nov. is proposed. The type strain is NBS58-1T=(KACC 21309T=MCCC 1K04037T). We also proposed Rufibacter quisquiliarum as a latter heterotypic synonym of Rufibacter ruber.

Jasmonic acid promotes leaf senescence through MYC2-mediated repression of CATALASE2 expression in Arabidopsis.

Plants relocate nutrients and energy from aging leaves to developing tissues during leaf senescence, which is important for plant growth, development, and responses to various environmental stimuli. Both jasmonic acid (JA) and H2O2 are two crucial signalling molecules positively regulating leaf senescence, whereas whether and how they are coordinated in leaf senescence remains elusive. Here, we report that H2O2 accumulates in JA-treated leaves, while scavenging the increased H2O2 can significantly suppresses JA-induced leaf senescence and the expression of senescence-associated genes (SAGs). The mutant myc2 with a mutation of MYC2, a master transcription factor in JA signalling pathway, exhibits delayed leaf senescence with increased catalase activity and decreased H2O2 accumulation compared with the wild type upon JA treatment. Further study showed that MYC2 downregulates CATALASE 2 (CAT2) expression by binding to its promoter, thus promoting JA-induced H2O2 accumulation and leaf senescence. Moreover, the delayed leaf senescence with reduced H2O2 accumulation and SAGs expression of the myc2 mutant is significantly reverted by the cat2-1 mutation in myc2 cat2-1 double mutant. Thus, our study reveals that JA represses CAT2 expression to increase H2O2 accumulation, thus promoting leaf senescence in a MYC2 dependent manner in Arabidopsis.

Agrococcus sediminis sp. nov., an actinobacterium isolated from lake sediment.

A novel strain, designated NS18T, was isolated from sediment sampled at Taihu Lake, PR China. Cells of the isolate were spherical, aerobic, non-motile, Gram-stain-positive and non-endospore-forming. Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain NS18T clustered in a clade of the genus Agrococcus. Its closest phylogenetic neighbour was Agrococcus lahaulensis DSM 17612T with 98.2 % 16S rRNA gene sequence similarity. The complete genome of NS18T was 2 736 037 bp and its genomic DNA G+C content was 72.8 mol%. The average nucleotide identity and digital DNA-DNA hybridization values between strain NS18T and A. lahaulensis DSM 17612T based on their whole genomes were 85.1 and 28.7 %, respectively. The major fatty acids were anteiso-C17 : 0 and anteiso-C15 : 0. The predominant menaquinones were MK11 and MK12. The polar lipids comprised diphosphatidylglycerol, phosphatidylglycerol and two unidentified lipids. The components of the peptidoglycan were Ala, Gly, Asp, Thr and DAB. The whole-cell sugars contained rhamnose, ribose, xylose and glucose. According to the results of phenotypic, chemotaxonomic and phylogenetic analyses, strain NS18T (=NBRC 113859T=MCCC 1K03759T) represents a novel species, for which the name Agrococcus sediminis sp. nov is proposed.

Efficient expression of novel glutamate decarboxylases and high level production of γ-aminobutyric acid catalyzed by engineered Escherichia coli.

Glutamate decarboxylase (GAD) has the potential of converting L-glutamate to gamma-aminobutyric acid (GABA), which is an important non-proteinogenic amino acid that has a potential use as food additive or dietary supplement for its physiological functions. A novel pyridoxal 5'-phosphate (PLP)-dependent glutamate decarboxylase (LsGAD) was cloned from GRAS (generally recognized as safe) Lactobacillus senmaizukei by genome mining and efficiently expressed in Escherichia coli BL21. The LsGAD displayed excellent temperature property, pH property and kinetic parameters compared with the probe LbGAD and the other GADs. By increasing the copy number of the LsGAD encoding gene, the expression level of LsGAD and the biosynthesis yield of GABA were increased, which was near to 2 times of that was expressed in single copy. These results established a solid foundation for increasing the added value of L-glutamate and the biosynthesis of GABA.

High level and enantioselective production of L-phenylglycine from racemic mandelic acid by engineered Escherichia coli using response surface methodology.

L-Phenylglycine (L-PHG) is a member of unnatural amino acids, and becoming more and more important as intermediate for pharmaceuticals, food additives and agrochemicals. However, the existing synthetic methods for L-PHG mainly rely on toxic cyanide chemistry and multistep processes. To provide green, safe and high enantioselective alternatives, we envisaged cascade biocatalysis for the one-pot synthesis of L-PHG from racemic mandelic acid. A engineered E. coli strain was established to co-express mandelate racemase, D-mandelate dehydrogenase and L-leucine dehydrogenase and catalyze a 3-step reaction in one pot, enantioselectively transforming racemic mandelic acid to give L-PHG (e.e. >99 %). After the conditions for biosynthesis of L-PHG optimized by response surface methodology, the yield and space-time yield of L-PHG can reach 87.89 % and 79.70 g·L-1·d-1, which was obviously improved. The high-yielding and enantioselective synthetic methods use cheap and green reagents, and E. coli whole-cell catalysts, thus providing green and useful alternative methods for manufacturing L-PHG.

Gemmobacter caeruleus sp. nov., a novel species originating from lake sediment.

An aerobic, Gram-stain-negative, non-spore-forming and rod-shaped bacterial strain, designated N8T, was isolated from the interfacial sediment of Taihu Lake in PR China. The strain formed white to blue colonies on R2A agar. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain N8T represented a member of the genus Gemmobacter and was most closely related to Gemmobacter aquaticus A1-9T (97.97 %). The average nucleotide identity and digital DNA-DNAhybridization values between strain N8T and G. aquaticus A1-9T based on their whole genomes were 78.8 and 21.7 %, respectively. Q-10 was the main predominant ubiquinone. The major fatty acids were summed feature 8 (C18 : 1ω7c and/or C18 : 1ω6c), C18 : 0 and C16 : 0. The G+C content of the genomic DNA was 66.1 mol%. The polar lipids comprised phosphatidylethanolamine, phosphatidylglycerol, phosphatidylcholine, one unidentified phospholipid, two unidentified glycolipids and two unidentified lipids. Based on its physiological, biochemical and chemotaxonomic characteristics, strain N8T represents a novel species of the genus Gemmobacter, for which the name Gemmobacter caeruleus sp. nov. is proposed. The type strain is N8T=(KACC 21307T=MCCC 1K04036T).