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1.
Waste Manag ; 181: 44-56, 2024 May 30.
Article in English | MEDLINE | ID: mdl-38583272

ABSTRACT

Phosphate tailings (PT) was used to reduce the release of heavy metals (HMs) during pyrolysis and the leachable rate of residual HMs, and simultaneously improve the bioavailability of phosphorus in the sludge-based biochar. The concentration of heavy metals and the fractions determined by BCR method was used to investigate the release and the transformation of Zn, Pb, Mn, Ni and Cu during pyrolysis involved with the effects of temperature and the addition of PT. The respective pyrolysis experiments shows that the release of Zn and Pb increases with temperature for both sewage sludge (SS) and PT, and the bioavailable fractions (F1 + F2) of Mn, Ni, and Cu increases with temperature for PT. During co-pyrolysis, blended samples released lower quantities of Zn and Pb and presented lower bioavailability of HMs than the individual SS or PT. A synergistic effect of co-pyrolysis was evident for volatile Zn and Pb. The decomposition of CaMg (CO3)2 from PT produced CaO, by which the volatile ZnCl2 and PbCl2 were transformed into ZnO and PbO with less volatility and higher reactivity with SiO2 and Al2O3 than the chlorides. Then SiO2 and Al2O3 from SS acted as the final stabilizer to immobilize the oxides. The final product combined with SiO2 and Al2O3, such as ZnSiO4 and ZnAl2O4, were detected. The addition of PT also introduced more Ca and P into sludge to produce biochar with higher concentration of apatite phosphorus with higher bioavailability.


Subject(s)
Metals, Heavy , Phosphates , Phosphorus , Pyrolysis , Sewage , Sewage/chemistry , Metals, Heavy/chemistry , Metals, Heavy/analysis , Phosphorus/chemistry , Phosphates/chemistry , Charcoal/chemistry
2.
Front Public Health ; 12: 1332095, 2024.
Article in English | MEDLINE | ID: mdl-38633232

ABSTRACT

Introduction: Adolescent suicide is a prevalent issue globally, with various factors contributing to this phenomenon. This study aimed to investigate these factors and their interrelationships to better understand the causes of adolescent suicide and provide evidence for its prevention. Methods: This study conducted among middle school students in Liaoning Province, China, from April to May 2016, A cross-sectional survey was administered to 1,028 students aged 10-19, using instruments such as the Behavior Questionnaire-Revised (SBQ-R), Children's Perception of Interparental Conflict Scale (CPIC), and revised version of Inventory of Parent Attachment (IPPA-R). Result: Binary logistic regression analysis revealed that adolescents aged 15-19, adolescents with strong perceptions of parental conflict were at high risk of suicide intention. Adolescents living in rural areas, adolescents with high mother-child attachment, adolescents with high father-child attachment were at low risk of suicide intention. Furthermore, parent-child attachment played a mediating role between two dimensions of parental conflict perception (resolved situations and response effect) and suicide intention. Discussion: The study concludes that adolescents living in urban areas, older adolescents, adolescents with a high level of parental conflict intensity, and those with low levels of parent-child attachment are at high risk of suicide intention. parent-child attachment played a mediating role between two dimensions of parental conflict perception (resolved situations and response effect) and suicide intention. Interventions aimed at reducing family conflicts and improving parent-child relationships are recommended to decrease the incidence of adolescent suicide.


Subject(s)
Parents , Suicide , Adolescent , Humans , Cross-Sectional Studies , Parent-Child Relations , China/epidemiology , Students
3.
Org Lett ; 26(7): 1478-1482, 2024 Feb 23.
Article in English | MEDLINE | ID: mdl-38334422

ABSTRACT

Herein, a dual photoredox/nickel catalyzed formylation of aryl bromide with commercially available 2,2-dimethoxy-N,N-dimethylethan-1-amine as an effective CO source has been successfully achieved, delivering a series of aromatic aldehydes in moderate to good yields. Compared with the traditional reductive carbonylation process, this newly designed synthetic protocol provides a straightforward toolbox to access aromatic aldehydes, obviating the use of carbon monoxide and stoichiometric reductants. Finally, the utility of this direct formylation reaction was demonstrated in the pharmaceutical analogue synthesis.

4.
Front Oncol ; 13: 1291570, 2023.
Article in English | MEDLINE | ID: mdl-38107066

ABSTRACT

SSBP2-CSF1R is an important biomarker for clinical diagnosis and prognosis of Philadelphia chromosome-like acute lymphoblastic leukemia (Ph-like ALL). This case report presents a pediatric Ph-like ALL patient carrying the SSBP2-CSF1R fusion gene. The patient was resistant to most conventional chemotherapy regimens and to dasatinib, an inhibitor that has been reported to have a therapeutic effect on SSBP2-CSF1R fusion Ph-like ALL, as she remained minimal residual disease (MRD) positive (detection by flow cytometry) and SSBP2-CSF1R fusion gene (detection by RT-PCR) positive after five rounds of such regimens. We thus conducted a large-scale in vitro screening to assess the sensitivity of the patient's leukemic cells to anti-cancer drugs. Based on the susceptibility results, we chose to combine cytarabine, homoharringtonine, dexamethasone, fludarabine, vindesine, and epirubicin for treatment. Clinical results showed that after a course of treatment, both MRD and SSBP2-CSF1R fusion gene turned negative, and there was no recurrence during an 18-month follow-up. In conclusion, our study suggests that the SSBP2-CSF1R fusion gene may be an important biomarker of primary drug resistance in Ph-like ALL, and indicate that the combination of cytarabine, homoharringtonine, dexamethasone, fludarabine, vindesine, and epirubicin can achieve optimal therapeutic results in this category of patients.

5.
Front Public Health ; 11: 1165381, 2023.
Article in English | MEDLINE | ID: mdl-37397714

ABSTRACT

In recent years, the aging population and increasing medical expenses among the older adults have emerged as significant public health concerns. National governments must conduct medical expense accounting and implement measures to reduce the burden of medical costs on the older population. However, limited studies have focused on total medical expenditure from a macro perspective, with many researches exploring individual medical expenses from different perspectives. This review introduces the trend of population aging and its impact on health cost change, reviews research on the medical expense burden of the older population and contributing factors, and points out underlying problems and limitations of current studies. Based on the present studies, the review emphasizes the necessity of medical expense accounting and analyzes the medical expense burden of the older population. Future studies should explore the impacts of medical insurance funds and health service system reforms on reducing medical expenses and developing a supporting medical insurance reform plan.


Subject(s)
Health Expenditures , Costs and Cost Analysis
6.
Water Sci Technol ; 87(11): 2634-2647, 2023 Jun.
Article in English | MEDLINE | ID: mdl-37318916

ABSTRACT

Recovering phosphorus from incineration sludge sewage ash (ISSA) is a well-established technology, with a greater recovery potential than that of supernatant or sludge. ISSA can be utilized as a secondary raw material in the fertilizer industry, or as a fertilizer if heavy metal concentrations do not exceed permissible limits, thus reducing the cost of phosphorus recovery. Increasing the temperature to produce ISSA with higher solubility and plant availability of phosphorus is advantageous for both pathways. But a decrease in the extraction of phosphorus is also observed at high temperatures, thereby diminishing the overall economic benefits. In this study, CaCl2 was utilized to mitigate the decrease in the extraction rate and also to promote the bioavailability of phosphorus. The addition of CaCl2 (80 g/kg of dry sludge) effectively promoted the conversion of non-apatite inorganic phosphorus to apatite inorganic phosphorus at a rate of 87.73% at 750 °C. Furthermore, the decrease in the extraction rate of phosphorus at 1,050 °C was comparatively smaller in the presence of CaCl2. If iron flocculants are used to capture P in wastewater management, it may be necessary to pay special attention to the amount of addition and incineration temperature to maximize the economic potential of recycling.


Subject(s)
Phosphorus , Sewage , Calcium Chloride , Biological Availability , Fertilizers , Incineration
7.
Front Med (Lausanne) ; 10: 1265544, 2023.
Article in English | MEDLINE | ID: mdl-38249987

ABSTRACT

Introduction: Considering the role of bacteria in the onset of acute exacerbation of COPD (AECOPD), we hypothesized that the use of influenza-Streptococcus pneumoniae vaccination, oral probiotics or inhaled amikacin could prevent AECOPD. Methods: In this pilot prospective, muti-central, randomized trial, moderate-to-very severe COPD subjects with a history of moderate-to-severe exacerbations in the previous year were enrolled and assigned in a ratio of 1:1:1:1 into 4 groups. All participants were managed based on the conventional treatment recommended by GOLD 2019 report for 3 months, with three groups receiving additional treatment of inhaled amikacin (0.4 g twice daily, 5-7 days monthly for 3 months), oral probiotic Lactobacillus rhamnosus GG (1 tablet daily for 3 months), or influenza-S. pneumoniae vaccination. The primary endpoint was time to the next onset of moderate-to-severe AECOPD from enrollment. Secondary endpoints included CAT score, mMRC score, adverse events, and survival in 12 months. Results: Among all 112 analyzed subjects (101 males, 96 smokers or ex-smokers, mean ± SD age 67.19 ± 7.39 years, FEV1 41.06 ± 16.09% predicted), those who were given dual vaccination (239.7 vs. 198.2 days, p = 0.044, 95%CI [0.85, 82.13]) and oral probiotics (248.8 vs. 198.2 days, p = 0.017, 95%CI [7.49, 93.59]) had significantly delayed onset of next moderate-to-severe AECOPD than those received conventional treatment only. For subjects with high symptom burden, the exacerbations were significantly delayed in inhaled amikacin group as compared to the conventional treatment group (237.3 vs. 179.1 days, p = 0.009, 95%CI [12.40,104.04]). The three interventions seemed to be safe and well tolerated for patient with stable COPD. Conclusion: The influenza-S. pneumoniae vaccine and long-term oral probiotic LGG can significantly delay the next moderate-to-severe AECOPD. Periodically amikacin inhalation seems to work in symptomatic patients. The findings in the current study warrants validation in future studies with microbiome investigation.Clinical trial registration:https://clinicaltrials.gov/, identifier NCT03449459.

8.
J Mater Chem B ; 10(38): 7780-7788, 2022 10 05.
Article in English | MEDLINE | ID: mdl-36069204

ABSTRACT

Peptides are gaining popularity as neurodegenerative disease-targeting drugs due to their medicinal value and simplicity in the biomedical and pharmaceutical industry fields. Herein, based on previously studied ferrocene-modified dipeptide (Fc-dipeptide) ferrocene-L-Phe-L-Phe (Fc-FF), we developed four Fc-tripeptides, i.e., Fc-FFY, Fc-FFF, Fc-FFD, and Fc-FFK, to further study the anti-amyloid effects of peptide-based inhibitors. The results showed that all Fc-tripeptides inhibited the formation of insulin fibrils in a dose-dependent manner more responsive than Fc-FF. Meanwhile, Fc-FFY and Fc-FFF had a more significant inhibitory effect on insulin amyloid fibrillation than Fc-FFD and Fc-FFK. In addition, molecular dynamics simulations indicated that Fc-FFY and Fc-FFF were contacted mainly with the hydrophobic core residues of insulin chain A and chain B, respectively. The research indicated that Fc-tripeptides have potential effects in preventing protein misfolding diseases and could be further used to design effective anti-amyloidosis compounds.


Subject(s)
Insulin , Neurodegenerative Diseases , Amyloid/metabolism , Dipeptides/chemistry , Ferrous Compounds , Humans , Metallocenes/pharmacology , Peptides/chemistry , Peptides/pharmacology
9.
Plant J ; 111(4): 979-994, 2022 08.
Article in English | MEDLINE | ID: mdl-35694901

ABSTRACT

Chlorophyll (Chl) is made up of the tetrapyrrole chlorophyllide and phytol, a diterpenoid alcohol. The photosynthetic protein complexes utilize Chl for light harvesting to produce biochemical energy for plant development. However, excess light and adverse environmental conditions facilitate generation of reactive oxygen species, which damage photosystems I and II (PSI and PSII) and induce their turnover. During this process, Chl is released, and is thought to be recycled via dephytylation and rephytylation. We previously demonstrated that Chl recycling in Arabidopsis under heat stress is mediated by the enzymes chlorophyll dephytylase 1 (CLD1) and chlorophyll synthase (CHLG) using chlg and cld1 mutants. Here, we show that the mutants with high CLD1/CHLG ratio, by different combinations of chlg-1 (a knock-down mutant) and the hyperactive cld1-1 alleles, develop necrotic leaves when grown under long- and short-day, but not continuous light conditions, owing to the accumulation of chlorophyllide in the dark. Combination of chlg-1 with cld1-4 (a knock-out mutant) leads to reduced chlorophyllide accumulation and necrosis. The operation of CLD1 and CHLG as a Chl salvage pathway was also explored in the context of Chl recycling during the turnover of Chl-binding proteins of the two photosystems. CLD1 was found to interact with CHLG and the light-harvesting complex-like proteins OHP1 and LIL3, implying that auxiliary factors are required for this process.


Subject(s)
Arabidopsis , Chlorophyllides , Arabidopsis/genetics , Arabidopsis/metabolism , Chlorophyll/metabolism , Chlorophyllides/metabolism , Light , Photosynthesis , Photosystem I Protein Complex/metabolism , Photosystem II Protein Complex/genetics , Photosystem II Protein Complex/metabolism
11.
Plant Sci ; 302: 110682, 2021 Jan.
Article in English | MEDLINE | ID: mdl-33288004

ABSTRACT

Chlorophyll (Chl) is composed of a tetrapyrrole ring and a phytol tail, which facilitate light energy absorbance and assembly with photosynthetic protein complexes, respectively. Chl dephytylation, the hydrolytic removal of the phytol tail, is considered a pivotal step in diverse physiological processes, such as Chl salvage during repair of the photosystem, the Chl cycle in the adjustment of antenna size, and Chl breakdown in leaf senescence and fruit maturation. Moreover, phytol is a component of the tocopherols, a major form of vitamin E that is essential in the human diet. This phytol mostly comes from Chl hydrolysis. However, the authentic enzyme responsible for Chl dephytylation has proved elusive. CHLOROPHYLLASE (CLH) which was discovered over a century ago, was the first enzyme found to have dephytylation activity in vitro, but its role in Chl metabolism has been questioned and remains under debate. Recently, novel dephytylases, i.e., PHEOPHYTINASE (PPH) and CHLOROPHYLL DEPHYTYLASE1 (CLD1) have emerged from genetic studies, indicating that dephytylation in Chl catabolism involves different players and is more complicated than previously thought. Based on sequence homology, substrate specificity, and subcellular localization, CLH, PPH, and CLD1 belong to different types of dephytylase, which prompted us to re-examine the dilemmas and missing links that still exist in Chl metabolism. This review thus focuses on the hitherto unanswered questions involving the Chl dephytylation reaction by highlighting relevant literature, updating recent progress, and synthesizing ideas.


Subject(s)
Chlorophyll/metabolism , Photosynthesis , Phytol/metabolism , Plants/enzymology , Plants/metabolism
12.
Environ Sci Pollut Res Int ; 27(18): 22758-22769, 2020 Jun.
Article in English | MEDLINE | ID: mdl-32323229

ABSTRACT

Recently, the research on conversion of biodiesel by-products to high value-added products has received much attention, due to the adverse effects of large accumulations of biodiesel by-products caused by the rapid increase in biodiesel production. Herein, this study investigated the utilization of by-products crude glycerol (CG-1 and CG-2) from two different industrial methods of biodiesel production and the favorable fermentation conditions for the high yield of ß-farnesene by an engineered Escherichia coli F4, which harbored an optimized mevalonate pathway. Through analyzing by-products' components and fermentation performance, we found that CG-2 did not contain harmful impurities such as methanol and black solid impurities, and the ß-farnesene production was up to 2.7 g/L from CG-2, which was similar to that from pure glycerol (2.5 g/L) and higher than that (2.21 g/L) from CG-1. Therefore, CG-2 was more suitable for ß-farnesene production than CG-1, which might provide a reference for choosing a more suitable method on practical biodiesel production. Afterward, a variety of important fermentation conditions were explored using CG-2 as a substrate in shaken flasks. Under the optimal conditions (including induced cell density 1.0, initial cell density 0.25, temperature after induction 33 °C, initial medium pH 6.5), the yield of ß-farnesene from CG-2 reached 10.31 g/L in a 5-L bioreactor, which was 2.8-fold higher than initial conditions in shake flasks and was the highest yield of ß-farnesene produced from biodiesel by-products by fermentation as well. The recommended fermentation conditions in this work will provide a valuable reference for the industrial production of ß-farnesene utilizing biodiesel by-products.


Subject(s)
Biofuels , Sesquiterpenes , Escherichia coli , Fermentation , Glycerol
13.
J Mater Chem B ; 8(15): 3076-3086, 2020 04 21.
Article in English | MEDLINE | ID: mdl-32202581

ABSTRACT

Peptide-based inhibitors have gradually been implicated as drugs for treating protein folding diseases because of their favorable biocompatibility and low toxicity. To develop potential therapeutic strategies for amyloid-related disorders, short peptides modified by Fc, ferrocene-l-Phe-l-Phe (Fc-FF) and ferrocene-l-Phe-l-Tyr (Fc-FY), were used as inhibitors for the investigation of the aggregation behavior of insulin. Firstly, molecular docking predicted the interaction between both Fc-peptides and insulin. Then, the experimental data from ThT, DLS, CD and TEM confirmed that Fc-FF and Fc-FY effectively inhibited insulin fibrillation and disaggregated mature insulin fibrils. Based on a dose-dependent manner, both Fc-peptides can strongly inhibit insulin fibrillation, extend lag phase time, reduce final fibril formation (beyond 99% by Fc-peptides of 400 µM), decrease the formation of high-content ß-sheet structures and reduce the size of insulin fibrils. Additionally, we found that compared with Fc-FY, the better inhibitory effect of Fc-FF at concentration below 400 µM was mainly resulted from the difference in π-π interaction and hydrogen bonds between Fc-peptides and insulin, according to molecular dynamics analysis. Our results demonstrated Fc-peptides, Fc-FF and Fc-FY, may play effective roles in the development of new therapeutic drugs or strategies for amyloid-related disorders, and the molecular dynamics simulation may be helpful for designing appropriate inhibitors of anti-amyloidosis diseases.


Subject(s)
Amyloid beta-Peptides/antagonists & inhibitors , Ferrous Compounds/pharmacology , Insulin/metabolism , Metallocenes/pharmacology , Molecular Dynamics Simulation , Peptides/pharmacology , Amyloid beta-Peptides/metabolism , Animals , Cattle , Ferrous Compounds/chemistry , Metallocenes/chemistry , Particle Size , Peptides/chemistry , Protein Aggregates/drug effects , Surface Properties
14.
Biomedicines ; 8(1)2020 Jan 01.
Article in English | MEDLINE | ID: mdl-31906292

ABSTRACT

The aim of this review was to provide an updated overview of studies on the medical-biological activities of Cinnamomum osmophloeum (C. osmophloeum) in vitro and in vivo and the potential therapeutic use of natural agents prepared from this plant for the alleviation of oral mucositis (OM). Reported articles were collected using web search engine tools. The systematic review was organized according to the preferred reporting items for reviews and meta-analyses (PRISMA) statement. Additional sources were identified through cross-referencing to identify the potential use of C. osmophloeum in the alleviation of OM. The results disclosed that C. osmophloeum is comprised of bioactive ingredients that could act diversely as a reagent in anti-inflammation, antibacterial, antioxidant, anti-hyperglycemic, antidyslipidemia, anti-cancer, renal disease therapy and anti-hyperuricemia capacities. Recent studies revealed that the overall effects on anti-inflammation, wound repair, and the antibacterial and antioxidant activities of its constituents would act as a potential remedy for oral mucositis. Up-to-date in vitro and in vivo studies on the medical-biological activities of C. osmophloeum suggested that C. osmophloeum and its constituents could be promising remedies as adjuvants in OM therapy and warrant further investigation.

15.
Burns ; 46(3): 647-651, 2020 05.
Article in English | MEDLINE | ID: mdl-31629615

ABSTRACT

INTRODUCTION: In China, although burn treatment develops rapidly, and ranks in the forefront of the world, there is a relative shortage of burn specialists, which limits the development of burn education. In traditional curriculum of surgery education, burn surgery education accounts for few proportions, which results in the indifference to the burn surgery among medical students. To date, few research reported the application of Clinical pathway- Problem based Learning (CP-PBL) in burn surgery education. The objective of the study is to explore the teaching effect of this novel teaching method in burn surgery education. METHODS: A pilot study was performed. One hundred and six students were randomly divided into a Lecture based Learning (LBL) only group (control group) and a LBL combined Clinical pathway- Problem based Learning group (observation group). A set of test was designed as evaluation criteria based on questions of burn surgery in National Medical Licensing Examination (NMLE) from 2011 to 2018. RESULTS: The students with Clinical pathway- Problem based Learning had better academic performances in profession theory. Type A2 and Type A3/A4 scores in the observation group were higher than those in the control group (p < 0.05). The scores of the observation group were higher than those of control group in the domains of understanding and application (p < 0.05). They also have higher favorable impressions of learning experience. CONCLUSIONS: More active approaches yield more learning and are viewed more favorable, which provides a vital message for the evolution of curriculum in Chinese medical schools.


Subject(s)
Burns , Curriculum , Education, Medical, Undergraduate/methods , Specialties, Surgical/education , China , Female , Humans , Male , Problem-Based Learning , Random Allocation , Young Adult
16.
Chromosome Res ; 28(2): 129-138, 2020 06.
Article in English | MEDLINE | ID: mdl-31712937

ABSTRACT

Supernumerary B chromosomes (Bs) are nonessential chromosomes that are considered genetically inert. However, the maize B carries control elements that direct its behavior, such as that of nondisjunction, during the second pollen mitosis, and affects normal A chromosomes during cell division. Recently, the maize B has been found to contain transcriptionally active sequences and to affect the transcription of genes on A chromosomes. To better understand the regulatory mechanisms underlying the maize B, we constructed two small RNA libraries from maize B73 inbred lines with and without Bs. The sequencing results revealed that 18 known microRNAs (miRNAs) were significantly differentially expressed in response to the presence of the B, and most target mRNAs were characterized as transcription factors. Moreover, three novel B-derived miRNAs were identified via stem-loop reverse transcriptase-polymerase chain reaction (RT-PCR)-based analysis, and all showed consistent B-specific expression in almost all analyzed inbred lines and in all tissue types, including leaves, roots, and pollen grains. By the use of B-10L translocations, the three B-derived miRNAs were mapped to specific B regions. The results from this study suggest that the maize B can express miRNAs and affect the expression of A-derived miRNAs, which could regulate the expression of A-located genes.


Subject(s)
Chromosomes, Plant/genetics , Gene Expression Regulation, Plant , MicroRNAs/genetics , RNA Interference , Zea mays/genetics , Chromosome Mapping , Gene Library , High-Throughput Nucleotide Sequencing , Inbreeding , Plant Breeding , Sequence Analysis, RNA
17.
Mol Genet Genomics ; 295(2): 313-325, 2020 Mar.
Article in English | MEDLINE | ID: mdl-31729549

ABSTRACT

Supernumerary B chromosomes are dispensable parts of the nuclear genome and occur in all eukaryotic groups. They differ from the normal A chromosomes in morphology, genetic behavior, and inheritance. Because they are nonessential for individual development, B chromosomes are considered to be genetically inert and to lack functional genes. However, the maize B chromosome carries control elements that direct its behavior and affects A chromosomes during cell division. Therefore, the maize B chromosome might contain genic regions that differ from the genic regions of A chromosomes. Yet, only a few B-specific transcript sequences have been isolated. To identify more B-specific transcriptionally active sequences, we constructed de novo transcriptome assemblies for maize B73 inbred lines with 0B (+0B) and 2B (+2B). Comparative analysis of the B73 + 0B and B73 + 2B assemblies revealed that unigenes annotated to 201 gene ontology terms were differentially expressed. Using RT-PCR analysis of novel transcript sequences specific to B73 + 2B, we identified 32 novel B-related transcript sequences, and most sequences showed consistent B-specific transcription in different inbred lines. Moreover, 20 of those novel B-related transcript sequences were further confirmed to be located only on the B chromosome by genomic PCR analysis. A total of 19 novel B-specific transcript sequences were mapped to various positions along the B chromosome using B-10L translocations. Taken together, our results suggest that the maize B chromosome indeed affects the expression of A-located genes and that a substantial amount of novel B-specific transcriptionally active sequences are present throughout the maize B chromosome. Therefore, the maize B chromosome seems not to be genetically inert.


Subject(s)
Chromosomes, Plant/genetics , Transcription, Genetic , Translocation, Genetic/genetics , Zea mays/genetics , Genome, Plant/genetics , Genomics , In Situ Hybridization, Fluorescence , Sequence Analysis, DNA
18.
Plant Signal Behav ; 12(11): e1382797, 2017 Nov 02.
Article in English | MEDLINE | ID: mdl-28937840

ABSTRACT

Tocopherols are synthesized in photosynthetic organisms, playing a role in plant stress tolerance. Recent studies showed that the phytol moiety of tocopherols comes from the salvaged phytol chain during chlorophyll degradation. However, the enzyme(s) responsible for chlorophyll dephytylation remains unclear. Recently, we reported the identification and characterization of CHLOROPHYLL DEPHYTYLASE1 (CLD1) of Arabidopsis, suggesting its role in chlorophyll turnover at steady state. In this addendum to the report, we presented and discussed the results related to the function of CLD1 in tocopherol biosynthesis. The tocopherol levels in the mature seeds were not altered in the transgenic lines with reduced CLD1 expression but were moderately increased in the plants with supraoptimal CLD1 activity compared to wild type. These results suggest that manipulating CLD1 activity could affect tocopherol biosynthesis to a certain extent and that other dephytylating enzymes are sharing redundant function in contributing the phytol pool in plant cells.


Subject(s)
Arabidopsis Proteins/metabolism , Arabidopsis/metabolism , Seeds/metabolism , Arabidopsis/genetics , Arabidopsis Proteins/genetics , Chlorophyll/metabolism , Gene Expression Regulation, Plant , Phytol/metabolism , Seeds/genetics , Tocopherols/metabolism
19.
Plant Cell ; 28(12): 2974-2990, 2016 12.
Article in English | MEDLINE | ID: mdl-27920339

ABSTRACT

Chlorophyll turns over in green organs during photosystem repair and is salvaged via de- and rephytylation, but the enzyme involved in dephytylation is unknown. We have identified an Arabidopsis thaliana thylakoid protein with a putative hydrolase domain that can dephytylate chlorophyll in vitro and in vivo. The corresponding locus, CHLOROPHYLL DEPHYTYLASE1 (CLD1), was identified by mapping a semidominant, heat-sensitive, missense allele (cld1-1). CLD1 is conserved in oxygenic photosynthetic organisms, sharing structural similarity with pheophytinase, which functions in chlorophyll breakdown during leaf senescence. Unlike pheophytinase, CLD1 is predominantly expressed in green organs and can dephytylate chlorophyll in vitro. The specific activity is significantly higher for the mutant protein encoded by cld1-1 than the wild-type enzyme, consistent with the semidominant nature of the cld1-1 mutation. Supraoptimal CLD1 activities in cld1-1 mutants and transgenic seedlings led to the proportional accumulation of chlorophyllides derived from chlorophyll dephytylation after heat shock, which resulted in light-dependent cotyledon bleaching. Reducing CLD1 expression diminished thermotolerance and the photochemical efficiency of photosystem II under prolonged moderate heat stress. Taken together, our results suggest that CLD1 is the long-sought enzyme for removing the phytol chain from chlorophyll during its turnover at steady state within the chloroplast.


Subject(s)
Arabidopsis Proteins/metabolism , Arabidopsis/metabolism , Chlorophyll/metabolism , Alleles , Chlorophyllides/metabolism
20.
J Fluoresc ; 26(5): 1699-708, 2016 Sep.
Article in English | MEDLINE | ID: mdl-27349802

ABSTRACT

A new efficient chemosensor 1 was prepared, for the detection of Fe(3+) in solutions as a colorimetric and fluorescent sensor. The visual and fluorescent behaviors of the receptor toward various metal ions were also explored. The receptor shows exclusive response toward Fe(3+) ions and also distinguishes Fe(3+) from other cations by color change and fluorescence enhancement in hydroalcoholic solution (MeOH/H2O = 9/1, v/v). Thus, the receptor can be used as a colorometric and fluorescent sensor for the determination of Fe(3+) ion. The fluorescence microscopy experiments showed that the chemosensor is efficient for detection of Fe(3+) in vitro, developing a good image of the biological organelles. Graphical Abstract ᅟ.

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