Summary
Phosphate (Pi) deficiency in soils is a major limiting factor for plant growth. In response to Pi deprivation, one prominent metabolic adaptation in plants is the decrease in membrane ...phospholipids that consume approximately one‐third cellular Pi. The level of two phospholipid‐hydrolyzing enzymes, phospholipase Dζ2 (PLDζ2) and non‐specific phospholipase C4 (NPC4), is highly induced in Pi‐deprived Arabidopsis. To determine the role of PLDζ2 and NPC4 in plant growth under Pi limitation, Arabidopsis plants deficient in both PLDζ2 and NPC4 (npc4pldζ2) were generated and characterized. Lipid remodeling in leaves and roots was analyzed at three different durations of Pi deficiency. NPC4 affected lipid changes mainly in roots at an early stage of Pi deprivation, whereas PLDζ2 exhibited a more overt effect on lipid remodeling in leaves at a later stage of Pi deprivation. Pi deficiency‐induced galactolipid increase and phospholipid decrease were impeded in pldζ2 and npc4pldζ2 plants. In addition, seedlings of npc4pldζ2 had the same root hair density as pldζ2 but shorter root hair length than pldζ2 in response to Pi deficiency. The loss of NPC4 decreased root hair length but had no effect on root hair density. These data suggest that PLDζ2 and NPC4 mediate the Pi deprivation‐induced lipid remodeling in a tissue‐ and time‐specific manner. PLDζ2 and NPC4 have distinctively different roles in root hair growth and development in response to Pi deprivation; PLDζ2 negatively modulates root hair density and length, whereas NPC4 promotes root hair elongation.
Significance Statement
This study reveals that PLDζ2 and NPC4, the two most highly induced phospholipases under Pi deficiency, have distinguishable roles in lipid remodeling and root hair growth in plant adaption to low Pi availability.
The phospholipase D (PLD) family in higher plants is composed of multiple members, and each of the
Arabidopsis PLDs characterized displays distinguishable properties in activity regulation and/or ...lipid preferences. The molecular and biochemical heterogeneities of the plant PLDs play important roles in the timing, location, and amount of phosphatidic acid (PA) produced. PLD-catalyzed production of PA has been shown to play important roles in plant growth, development, and response to various stresses, including drought, salinity, freezing, and nutrient deficiency. PLD and PA affect cellular processes through different modes of action, including direct target protein binding and biophysical effects on cell membranes. Improved knowledge on the mechanism by which specific PLDs and PA mediate given plant responses will facilitate the understanding of the molecular processes that connect the stimulus perception on membranes to intracellular actions and physiological responses.
•Similar primary zirconia properties by speed-sintering as conventional sintering.•Speed-sintering 3Y-TZP decreased its translucency but not that of 5Y-PSZ.•Speed-sintering lowered the mechanical ...reliability of 3Y-TZP and 5Y-PSZ zirconia.
To evaluate the performance of zirconia ceramics sintered in a speed sintering induction furnace by comprehensive understanding of their optical and mechanical properties, microstructure, phase composition and aging stability, in comparison to ceramics sintered in a conventional furnace.
Speed sintered (SS) Katana STMLSS (Kuraray Noritake) (total thermal cycle/sintering time/dwell temperature: 30min/16min/1560°C) and CEREC Zirconia (CEREC ZrSS) (Dentsply Sirona) (15min/2min/1578°C) were compared to conventionally sintered (CS) Katana STMLCS (6.8h/2h/1550°C) and inCoris TZICS (4h/2h/1510°C). The translucency parameter (TP) and contrast ratio (CR) were measured with a spectrophotometer. The chemical composition of the materials was determined by XRF and phase composition was characterized using XRD. Hydrothermal aging behavior was evaluated by measuring the tetragonal-to-monoclinic ZrO2 phase transformation after accelerated hydrothermal aging in steam at 134°C. The indentation fracture toughness, Vickers hardness and biaxial strength of the sintered ceramics were assessed.
Speed and conventionally sintered zirconia revealed similar density, microstructure, average strength and hydrothermal aging stability. Both Katana STMLSS/CS 5Y-PSZ ceramics were characterized with a higher content of cubic phase (≈53wt%), which resulted in a higher amount of Y2O3 in the remaining tetragonal ZrO2 phases compared to the 3Y-TZP CEREC ZrSS and inCoris TZICS (8 and 20wt%, respectively). The sintering program did not affect the hydrothermal aging behavior of Katana STMLSS and CEREC ZrSS. TP of Katana STMLSS (TP≈32) was not affected by speed sintering, while the translucency of CEREC ZrSS (TP=14) was significantly reduced. Hardness, fracture toughness and Weibull characteristic strength of Katana STMLSS and CEREC ZrSS also reached the optimal level, but speed sintering substantially lowered their mechanical reliability.
Speed sintering of 3Y-TZP and 5Y-PSZ in a speed sintering induction oven appeared suitable for clinical applications. However, further studies should focus on improving of translucency and mechanical reliability of the speed-sintered zirconia ceramics.
Phosphorus is an essential macronutrient that often limits plant growth and development. Under phosphorus-limited conditions, plants undergo substantial alterations in membrane lipid composition to ...cope with phosphorus deficiency. To characterize the changes in lipid species and to identify enzymes involved in plant response to phosphorus starvation, 140 molecular species of polar glycerolipids were quantitatively profiled in rosettes and roots of wild-type Arabidopsis (Arabidopsis thaliana) and phospholipase D knockout mutants pldζ1, pldζ2, and pldζ1pldζ2. In response to phosphorus starvation, the concentration of phospholipids was decreased and that of galactolipids was increased. Phospholipid lost in phosphorus-starved Arabidopsis rosettes was replaced by an equal amount of galactolipid. The concentration of phospholipid lost in roots was much greater than in rosettes. Disruption of both PLDζ1 and PLDζ2 function resulted in a smaller decrease in phosphatidylcholine and a smaller increase in digalactosyldiacylglycerol in phosphorus-starved roots. The results suggest that hydrolysis of phosphatidylcholine by PLDζs during phosphorus starvation contributes to the supply of inorganic phosphorus for cell metabolism and diacylglycerol moieties for galactolipid synthesis.
To evaluate the overall efficacy and safety of endoscopic enucleation of the prostate (EP) vs open prostatectomy (OP) for large benign prostatic hyperplasia (BPH).
We conducted an electronic search ...of PubMed/Medline, EMBASE, The Cochrane Library, and Web of Science to detect all relevant randomized controlled trials (RCTs) comparing EP with OP. A meta-analysis was performed using Review Manager 5.3.
Seven RCTs (735 patients) were included. At the 3-, 6- and 12-month follow-up, there were no significant differences in the International Prostate Symptom Score (IPSS), maximum flow rate (Qmax), quality of life (QoL) score and post-void residual urine volume (PVR) between EP and OP. The International Index of Erectile Function (IIEF-5) was higher with EP (weighted mean difference WMD: 1.00, 95% confidence interval CI: 0.21 to 1.78, p=0.01) at the 12-month follow-up. The catheterization time (WMD: 3.80 d, 95%CI: -5.11 to -2.48, P<0.00001) and hospital stay (WMD: 4.93 d, 95%CI: -5.96 to -3.89, P<0.00001) were shorter with EP. The duration of operation was longer for EP compared with OP (WMD: 16.21 min, 95%CI: 3.72 to 28.70, P=0.01). The resected tissue weight (WMD: -9.63 g, 95%CI: -14.46 to -4.81, P<0.0001) and decrease in hemoglobin (WMD: -1.14 g/dL, 95%CI: -1.81 to -0.47, P=0.0008) were less with EP. EP was associated with fewer blood transfusions (risk ratio: 0.22, 95%CI: 0.10 to 0.47, P=0.0001). There were no significant differences between EP and OP when comparing other complications.
Although only a limited number of RCTs with relatively limited follow-up are available, EP is shown to have a similar postoperative profile and comparable safety to OP. By contrast, EP may have a more desirable perioperative profile. EP appears to be an effective and safe minimally invasive option for treating large prostates that requires only brief convalescence.
Summary
Abietane diterpenoids are major constituents of conifer resins that have important industrial and medicinal applications. However, their function in plants is poorly understood. Here we show ...that dehydroabietinal (DA), an abietane diterpenoid, is an activator of systemic acquired resistance (SAR), which is an inducible defense mechanism that is activated in the distal, non‐colonized, organs of a plant that has experienced a local foliar infection. DA was purified as a SAR‐activating factor from vascular sap of Arabidopsis thaliana leaves treated with a SAR‐inducing microbe. Locally applied DA is translocated through the plant and systemically induces the accumulation of salicylic acid (SA), an important activator of defense, thus leading to enhanced resistance against subsequent infections. The NPR1 (NON‐EXPRESSOR OF PR GENES1), FMO1 (FLAVIN‐DEPENDENT MONOOXYGENASE1) and DIR1 (DEFECTIVE IN INDUCED RESISTANCE1) genes, which are critical for biologically induced SAR, are also required for the DA‐induced SAR, which is further enhanced by azelaic acid, a defense priming molecule. In response to the biological induction of SAR, DA in vascular sap is redistributed into a SAR‐inducing ‘signaling DA’ pool that is associated with a trypsin‐sensitive high molecular weight fraction, a finding that suggests that DA‐orchestrated SAR involves a vascular sap protein(s).
Pathogen infection of higher plants often induces rapid production of phosphatidic acid (PA) and changes in lipid profiles, but the enzymatic basis and the function of the lipid change in ...pathogen–plant interactions are not well understood.
Infection of phospholipase D β1 (PLDβ1)-deficient plants by Pseudomonas syringae tomato pv DC3000 (Pst DC30000) resulted in less bacterial growth than in wild-type plants, and the effect was more profound in virulent Pst DC3000 than avirulent Pst DC3000 (carrying the avirulence gene avrRpt2) infection. The expression levels of salicylic acid (SA)-inducible genes were higher, but those inducible by jasmonic acid (JA) showed lower expression in PLDβ1 mutants than in wild-type plants.
However, PLDβ1-deficient plants were more susceptible than wild-type plants to the fungus Botrytis cinerea. The PLDβ1-deficient plants had lower levels of PA, JA and JA-related defense gene expression after B. cinerea inoculation.
PLDβ1 plays a positive role in pathogen-induced JA production and plant resistance to the necrotrophic fungal pathogen B. cinerea, but a negative role in the SA-dependent signaling pathway and plant tolerance to infection with biotrophic Pst DC3000. PLDβ1 is responsible for most of the increase in PA production in response to necrotrophic B. cinerea and virulent Pst DC3000 infection, but contributes less to avirulent Pst DC3000 (avrRpt2)-induced PA production.
Summary
Glycerophosphodiester phosphodiesterase (GDPD), which hydrolyzes glycerophosphodiesters into sn‐glycerol‐3‐phosphate (G‐3‐P) and the corresponding alcohols, plays an important role in various ...physiological processes in both prokaryotes and eukaryotes. However, little is known about the physiological significance of GDPD in plants. Here, we characterized the Arabidopsis GDPD family that can be classified into canonical GDPD (AtGDPD1‐6) and GDPD‐like (AtGDPDL1‐7) subfamilies. In vitro analysis of enzymatic activities showed that AtGDPD1 and AtGDPDL1 hydrolyzed glycerolphosphoglycerol, glycerophosphocholine and glycerophosphoethanolamine, but the maximum activity of AtGDPD1 was much higher than that of AtGDPDL1 under our assay conditions. Analyses of gene expression patterns revealed that all AtGDPD genes except for AtGDPD4 were transcriptionally active in flowers and siliques. In addition, the gene family displayed overlapping and yet distinguishable patterns of expression in roots, leaves and stems, indicating functional redundancy as well as specificity of GDPD genes. AtGDPDs but not AtGDPDLs are up‐regulated by inorganic phosphate (Pi) starvation. Loss‐of‐function of the plastid‐localized AtGDPD1 leads to a significant decrease in GDPD activity, G‐3‐P content, Pi content and seedling growth rate only under Pi starvation compared with the wild type (WT). However, membrane lipid compositions in the Pi‐deprived seedlings remain unaltered between the AtGDPD1 knockout mutant and WT. Thus, we suggest that the GDPD‐mediated lipid metabolic pathway may be involved in release of Pi from phospholipids during Pi starvation.
A direct‐infusion electrospray ionization triple–quadrupole mass spectrometry method with multiple reaction monitoring (MRM) was employed to measure 264 lipid analytes extracted from leaves of ...Arabidopsis thaliana subjected to mechanical wounding. The method provided precise measurements with an average coefficient of variation of 6.1%. Lipid classes analyzed comprised galactolipids and phospholipids (including monoacyl molecular species, molecular species with oxidized acyl chains, phosphatidic acids (PAs)), tri‐ and tetra‐galactosyldiacylglycerols (TrGDGs and TeGDGs), head‐group‐acylated galactolipids, and head‐group‐acylated phosphatidylglycerol (acPG), sulfoquinovosyldiacylglycerols (SQDGs), sphingolipids, di‐ and tri‐acylglycerols (DAGs and TAGs), and sterol derivatives. Of the 264 lipid analytes, 254 changed significantly in response to wounding. In general, levels of structural lipids decreased, whereas monoacyl molecular species, galactolipids and phosphatidylglycerols (PGs) with oxidized fatty acyl chains, PAs, TrGDGs, TeGDGs, TAGs, head‐group‐acylated galactolipids, acPG, and some sterol derivatives increased, many transiently. The observed changes are consistent with activation of lipid oxidizing, hydrolyzing, glycosylating, and acylating activities in the wounding response. Correlation analysis of the levels of lipid analytes across individual control and treated plants was used to construct a lipid dendrogram and to define clusters and sub‐clusters of lipid analytes, each composed of a group of lipids which occurred in a coordinated manner. Current knowledge of metabolism supports the notion that observed sub‐clusters comprise lipids generated by a common enzyme and/or metabolically downstream of a common enzyme. This work demonstrates that co‐occurrence analysis, based on correlation of lipid levels among plants, is a powerful approach to defining lipids generated in vivo by a common enzymatic pathway.
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