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1.
bioRxiv ; 2024 Jan 12.
Article in English | MEDLINE | ID: mdl-38260362

ABSTRACT

In response to antigens, B cells undergo affinity maturation and class switching mediated by activation-induced cytidine deaminase (AID) in germinal centers (GCs) of secondary lymphoid organs, but uncontrolled AID activity can precipitate autoimmunity and cancer. The regulation of GC antibody diversification is of fundamental importance but not well understood. We found that autoimmune regulator (AIRE), the molecule essential for T cell tolerance, is expressed in GC B cells in a CD40-dependent manner, interacts with AID and negatively regulates antibody affinity maturation and class switching by inhibiting AID function. AIRE deficiency in B cells caused altered antibody repertoire, increased somatic hypermutations, elevated autoantibodies to T helper 17 effector cytokines and defective control of skin Candida albicans. These results define a GC B cell checkpoint of humoral immunity and illuminate new approaches of generating high-affinity neutralizing antibodies for immunotherapy.

2.
Environ Sci Pollut Res Int ; 30(60): 125677-125688, 2023 Dec.
Article in English | MEDLINE | ID: mdl-38001293

ABSTRACT

The treatment of cooking oil wastewater is an urgent issue need to be solved. We aimed to screen for efficient oil-degrading bacteria and develop a new microbial agent for degrading waste cooking oil in oily wastewater. Three extremely effective oil-degrading bacteria, known as YZQ-1, YZQ-3, and YZQ-4, were found by the enrichment and acclimation of samples from various sources and separation using oil degradation plates. The 16S rRNA sequencing analysis and phylogenetic tree construction showed that the three strains were Bacillus tropicus, Pseudomonas multiresinivorans, and Raoultella terrigena. Under optimal degradation conditions, the maximal degradation rates were 67.30 ± 3.69%, 89.65 ± 1.08%, and 79.60 ± 5.30%, respectively, for YZQ-1, YZQ-3, and YZQ-4. Lipase activity was highest for YZQ-3, reaching 94.82 ± 12.89 U/L. The best bacterial alliance was obtained by adding equal numbers of microbial cells from the three strains. Moreover, when this bacterial alliance was applied to oily wastewater, the degradation rate of waste cooking oil was 61.13 ± 7.30% (3.67% ± 2.13% in the control group), and COD removal was 62.4% ± 5.65% (55.60% ± 0.71% in the control group) in 72 h. Microbial community analysis results showed YZQ-1 and YZQ-3 were adaptable to wastewater and could coexist with local bacteria, whereas YZQ-4 could not survive in wastewater. Therefore, the combination of YZQ-1 and YZQ-3 can efficiently degrade oil and shows great potential for oily wastewater treatment.


Subject(s)
Oils , Wastewater , RNA, Ribosomal, 16S/metabolism , Phylogeny , Bacteria/metabolism , Biodegradation, Environmental
3.
Huan Jing Ke Xue ; 44(9): 5102-5113, 2023 Sep 08.
Article in Chinese | MEDLINE | ID: mdl-37699828

ABSTRACT

Microplastics (MPs) in soil have attracted extensive attention as an emerging pollutant, and the transport of MPs is affected by their own physical and chemical properties, the chemical composition of soil solutions, and soil minerals. However, in the presence of oxides, the underlying mechanism for the transport of MPs in different ionic types and ionic strengths is still not fully understood. In this study, the effects of ionic type, ionic strength, and iron oxide on the transport of polystyrene microplastics (PSMPs) with different functional groups were investigated through stability experiments and transport experiments. The colloid transport model, CD-MUSIC model, and DLVO theory were used to explore the transport mechanism. The results showed that normalized concentrations (c/c0) of PSMPs were 0.99 in the NaH2PO4 background and 0.94 in the CaCl2 background, respectively, which indicated that the strongest stability of PSMPs was observed in the former and the weakest in the latter. Different ionic types had different effects on the transport of PSMPs. For the cations Na+ and Ca2+, Ca2+ strongly inhibited PSMPs transport in pure quartz sand because of the bridging effect and strong charge neutralization effect; the recovery rate of the PSMPs in the effluent was (43.83±1.71)%, and a first-order retention coefficient on the second kinetic Site-2 (k2a) was 1.54 min-1. The presence of iron oxide enhanced the inhibition, the recovery rate of the PSMPs in the effluent decreased to (6.04±0.40)%, and k2a increased to 5.33 min-1. For the anions Cl- and PO43-, the transport of PSMPs in pure quartz sand was dominated by surface electronegativity of PSMPs, and PSMPs exhibited lower electronegativity under Cl- background and thus showed higher recovery[(92.95±0.63)%] and lower k2a (0.19 min-1). However, in the presence of iron oxides, the Zeta potential of the quartz sand surface was the controlling factor for PSMPs transport. According to results of the CD-MUSIC model, PO43- could be easily adsorbed on the iron oxide surface to form innersphere complexes, which reduced the surface electronegativity of the iron-loaded quartz sand and enhanced the transport of PSMPs, higher recovery[(76.22±1.39)%], and lower k2a (0.66 min-1). Moreover, the species of the formed innersphere complex was controlled by the PO43- concentration, and different species of innersphere complexes had distinct negative surface charges. Higher surface electronegativity of the iron-loaded quartz sand was observed under higher PO43- concentration, which was not conducive to the transport of PSMPs. Further, the transport ability of PSMPs decreased with the increase in ionic strength. Finally, the Derjaguin-Landau-Verwey-Overbeek (DLVO) theory was used to calculate the variation in the primary barrier between PSMPs and the collector under the conducted experimental conditions, which helped better elucidate the transport behavior of PSMPs. The variation in the primary barrier was consistent with the transport ability of PSMPs, and a higher primary barrier indicated a larger repulsion between PSMPs and the collector, which was in favor of PSMPs transport.

4.
Environ Sci Pollut Res Int ; 30(37): 87913-87924, 2023 Aug.
Article in English | MEDLINE | ID: mdl-37430081

ABSTRACT

Waste classification management is effective in addressing the increasing waste output and continuous deterioration of environmental conditions. The waste classification behaviour of resident is an important basis for managers to collect and allocate resources. Traditional analysis methods, such as questionnaire, have limitations considering the complexity of individual behaviour. An intelligent waste classification system (IWCS) was applied and studied in a community for 1 year. Time-based data analysis framework was constructed to describe the residents' waste sorting behaviour and evaluate the IWCS. The results showed that residents preferred to use face recognition than other modes of identification. The ratio of waste delivery frequency was 18.34% in the morning and 81.66% in the evening, respectively. The optimal time windows of disposing wastes were from 6:55 to 9:05 in the morning and from 18:05 to 20:55 in the evening which can avoid crowding. The percentage of accuracy of waste disposal increased gradually in a year. The amount of waste disposal was largest on every Sunday. The average accuracy was more than 94% based on monthly data, but the number of participating residents decreased gradually. Therefore, the study demonstrates that IWCS is a potential platform for increasing the accuracy and efficiency of waste disposal and can promote regulations implementation.


Subject(s)
Recycling , Refuse Disposal , Solid Waste , Waste Management , Garbage , Solid Waste/classification , Waste Management/methods , China
5.
Cell Rep ; 42(6): 112577, 2023 06 27.
Article in English | MEDLINE | ID: mdl-37267110

ABSTRACT

Localization of a variety of RNAs to non-membrane-bound cellular compartments such as nucleoli and Cajal bodies is critical for their stability and function. The molecular mechanisms that underly the recruitment and exclusion of RNAs from these phase-separated organelles is incompletely understood. Telomerase is a ribonucleoprotein composed of the reverse transcriptase protein telomerase reverse transcriptase (TERT), the telomerase RNA (TR), and several auxiliary proteins, including TCAB1. Here we show that in the absence of TCAB1, a large fraction of TR is tightly bound to the nucleolus, while TERT is largely excluded from the nucleolus, reducing telomerase assembly. This suggests that nuclear compartmentalization by the non-membrane-bound nucleolus counteracts telomerase assembly, and TCAB1 is required to retain TR in the nucleoplasm. Our work provides insight into the mechanism and functional consequences of RNA recruitment to organelles formed by phase separation and demonstrates that TCAB1 plays an important role in telomerase assembly.


Subject(s)
Telomerase , Cell Nucleolus/metabolism , Cell Nucleus/metabolism , RNA/metabolism , Telomerase/metabolism , Humans , HeLa Cells
6.
J Memb Sci ; 672: 121473, 2023 Apr 15.
Article in English | MEDLINE | ID: mdl-36785656

ABSTRACT

The COVID-19 pandemic has caused serious social and public health problems. In the field of personal protection, the facial masks can prevent infectious respiratory diseases, safeguard human health, and promote public safety. Herein, we focused on preparing a core filter layer for masks using electrospun polyvinyl butyral/apocynum venetum extract nanofibrous membranes (PVB/AVE NMs), with durable interception efficiency and antibacterial properties. In the spinning solution, AVE acted as a salt to improve electrical conductivity, and achieve long-lasting interception efficiency with adjustable pore size. It also played the role of an antibacterial agent in PVB/AVE NMs to achieve win-win effects. The hydrophobicity of PVB-AVE-6% was 120.9° whereas its filterability reached 98.3% when the pressure drop resistance was 142 Pa. PVB-AVE-6% exhibited intriguing properties with great antibacterial rates of 99.38% and 98.96% against S. aureus and E. coli, respectively. After a prolonged usability test of 8 h, the filtration efficiency of the PVB/AVE masks remained stable at over 97.7%. Furthermore, the antibacterial rates of the PVB/AVE masks on S. aureus and E. coli were 96.87% and 96.20% respectively, after using for 2 d. These results indicate that PVB/AVE NMs improve the protective performance of ordinary disposable masks, which has certain application in air filtration.

7.
Environ Technol ; : 1-13, 2023 Mar 08.
Article in English | MEDLINE | ID: mdl-36846968

ABSTRACT

ABSTRACTAerobic composting of food waste (FW) from rural China using a composting device results in a substantial financial burden on the government. This study aimed to assess the feasibility of mitigating this cost using vermicomposting of composted FW. The specific aims were to elucidate the effects of composted FW on earthworm growth and reproduction, reveal the changes in the physical and chemical properties of earthworm casts during vermicomposting, identify the microbial community structure associated with vermicomposting, and perform a financial analysis based on the yield of earthworms and earthworm casts. Mixing composted FW and mature cow dung in an equal ratio achieved the highest earthworm reproduction rate, where 100 adult earthworms produced 567 juvenile earthworms and 252 cocoons in 40 d. Earthworms reduce salt content of vermicomposting substrates by assimilating Na+ and promoting humification by transforming humin into humic and fulvic acid, thus producing earthworm casts with a high generation index > 80%. When composted FW was added to a vermicomposting substrate, a distinctive microbial community structure with alkaliphilic, halophilic, and lignocellulolytic microorganisms dominated the microflora. The dominant bacterial species was Saccharopolyspora rectivirgula, and the dominant fungal species changed from Kernia nitida to Coprinopsis scobicola. Furthermore, microbial genes for refractory organic matter and fat degradation were observed in Vibrio cholerae, Kernia nitida, and Coprinopsis scobicola. Financial analysis showed that vermicomposting has the potential to reduce the cost associated with FW disposal from $ 57 to $ 18/t.

8.
Environ Technol ; 44(27): 4199-4209, 2023 Nov.
Article in English | MEDLINE | ID: mdl-35678156

ABSTRACT

Food waste is a potential resource to prepare microbial fertilizer. However, functional microorganisms derived from the food waste compost (FWC) are relatively lacking. We have isolated, identified, characterized and optimized a high-yielding indole-3-acetic acid (IAA) strain from FWC and further evaluated its growth promoting effect on plants. A IAA high-yielding strain, Providencia sp.Y, with an initial IAA yield of 139.98 mg L-1, was obtained through high-throughput screening, and identified by 16S rRNA gene sequence. The novel strain Y may simultaneously involve the following three pathways from L-tryptophan to IAA, which were identified using liquid chromatography-tandem mass spectrometry: (1) L-tryptophan-indole-3-ethanol-indole-3-acetaldehyde-indole-3-acetic acid; (2) L-tryptophan-1-hydroxy-indole-3-ethanol-indole-3-acetic acid; (3) L-tryptophan-indole-3-acetamide-indole-3-acetic acid. The most suitable comprehensive conditions for IAA production, which were optimized by single factor experiment, were: culture time 12 h, inoculation amount 2% (v/v), NaCl concentration 4% (w/v), culture temperature 25℃, initial pH = 5, and L-tryptophan concentration 3.0 g L-1. The yield of IAA after optimization was increased by 590.48%, from 139.98 mg L-1 (before optimization) to 966.54 mg L-1. Diluted 200-fold microbial suspension could significantly improve the growth of pakchoi seedlings. The seedling plant height, root length, leaf width, leaf length, and fresh weight with microbial suspension increased by 17.39%, 107.35%, 77.98%, 37.75%, and 215.38%, respectively, compared with those without microbial suspension. The increase was greater than that of commercial bacterial agents. In conclusion, this isolated strain can be used as an economical microbial inoculant and provides a new germplasm resource for developing microbial fertilizers.


Subject(s)
Composting , Refuse Disposal , Food , Tryptophan/metabolism , Fermentation , RNA, Ribosomal, 16S/genetics , Metabolic Networks and Pathways , Plants/genetics , Plants/metabolism
9.
Nucleic Acids Res ; 50(19): 11058-11071, 2022 10 28.
Article in English | MEDLINE | ID: mdl-36263813

ABSTRACT

DNA double strand breaks (DSBs) are induced by external genotoxic agents (ionizing radiation or genotoxins) or by internal processes (recombination intermediates in lymphocytes or by replication errors). The DNA ends induced by these genotoxic processes are often not ligatable, requiring potentially mutagenic end-processing to render ends compatible for ligation by non-homologous end-joining (NHEJ). Using single molecule approaches, Loparo et al. propose that NHEJ fidelity can be maintained by restricting end-processing to a ligation competent short-range NHEJ complex that 'maximizes the fidelity of DNA repair'. These in vitro studies show that although this short-range NHEJ complex requires DNA ligase IV (Lig4), its catalytic activity is dispensable. Here using cellular models, we show that inactive Lig4 robustly promotes DNA repair in living cells. Compared to repair products from wild-type cells, those isolated from cells with inactive Lig4 show a somewhat increased fraction that utilize micro-homology (MH) at the joining site consistent with alternative end-joining (a-EJ). But unlike a-EJ in the absence of NHEJ, a large percentage of joints isolated from cells with inactive Lig4 occur with no MH - thus, clearly distinct from a-EJ. Finally, biochemical assays demonstrate that the inactive Lig4 complex promotes the activity of DNA ligase III (Lig3).


Subject(s)
DNA End-Joining Repair , DNA Repair , DNA/genetics , DNA Breaks, Double-Stranded , DNA Ligase ATP/genetics , DNA Ligases/genetics , DNA Ligases/metabolism , Biocatalysis
10.
Acta Biochim Biophys Sin (Shanghai) ; 54(6): 759-766, 2022 May 25.
Article in English | MEDLINE | ID: mdl-35975606

ABSTRACT

Activation-induced cytidine deaminase (AID) initiates somatic hypermutation of immunoglobulin (Ig) gene variable regions and class switch recombination (CSR) of Ig heavy chain constant regions. Two decades of intensive research has greatly expanded our knowledge of how AID functions in peripheral B cells to optimize antibody responses against infections, while maintaining tight regulation of AID to restrain its activity to protect B cell genomic integrity. The many exciting recent advances in the field include: 1) the first description of AID's molecular structure, 2) remarkable advances in high throughput approaches that precisely track AID targeting genome-wide, and 3) the discovery that the cohesion-mediate loop extrusion mechanism [initially discovered in V(D)J recombination studies] also governs AID-medicated CSR. These advances have significantly advanced our understanding of AID's biochemical properties in vitro and AID's function and regulation in vivo. This mini review will discuss these recent discoveries and outline the challenges and questions that remain to be addressed.


Subject(s)
Cytidine Deaminase , Somatic Hypermutation, Immunoglobulin , B-Lymphocytes , Cytidine Deaminase/chemistry , Cytidine Deaminase/genetics , Immunoglobulin Class Switching/genetics , Somatic Hypermutation, Immunoglobulin/genetics
11.
J Hazard Mater ; 440: 129716, 2022 10 15.
Article in English | MEDLINE | ID: mdl-35952431

ABSTRACT

Microbial bioremediation offers a solution to the problem of residual antibiotics in wastewater associated with animal farms. Efficient degradation of antibiotic residues depends upon the genetic make-up of microbial degraders, which requires a comprehensive understanding of the degradation mechanisms. In this study, a novel, efficient tylosin (TYL)-degrading bacterium, Providencia stuartii TYL-Y13 (Y13) was isolated, which could completely degrade 100 mg/L TYL within 15 h under optimal operating conditions at 40 â„ƒ, pH 7.0 %, and 1 % (v/v) bacterial inoculation rate. Whole genome sequencing revealed that strain Y13 consists of a circular chromosome and two plasmids. A new biodegradation pathway of TYL including desugarification, hydrolysis, and reduction reactions was proposed through the analysis of biodegradation products. It was demonstrated that strain Y13 gradually decreased the biotoxicity of TYL and its metabolites based on the results of the ecological structural activity relationships (ECOSAR) model analysis and toxicity assessment. Moreover, Y13 promoted the reduction of the target macrolide resistance genes in wastewater and disappeared within 84 h. These results shed new light on the mechanism of TYL biodegradation and better utilization of microbes to remediate TYL contamination.


Subject(s)
Tylosin , Wastewater , Animals , Anti-Bacterial Agents/chemistry , Anti-Bacterial Agents/pharmacology , Biodegradation, Environmental , Drug Resistance, Bacterial , Genetic Background , Macrolides , Providencia , Risk Assessment , Swine , Tylosin/chemistry
12.
Methods Mol Biol ; 2528: 55-66, 2022.
Article in English | MEDLINE | ID: mdl-35704185

ABSTRACT

During transcription and replication, R-loops that contain RNA-DNA hybrids are generated across numerous genomic loci and contribute to many biological events. Using S9.6, a monoclonal antibody against RNA-DNA hybrids, accelerated the study of R-loop biology. An outpouring of recent studies has implicated various contributions of R-loop in physiological cellular functions. Earlier studies using nondenaturing sodium bisulfite probing also supported existence of DNA-RNA hybrids formation in mammalian cells. In activated B cells, RNA-DNA hybrids formation at IgH gene locus of B cells is crucial for class switch recombination that ensure the proper effector function of the antibody. Here, we describe the identification of R-loops associated with the IgH locus using RNA-DNA hybrid immunoprecipitation sequencing and nondenaturing sodium bisulfite probing. This will be helpful for future studies of R-loops status on whole genome as well as on IgH locus in B cells.


Subject(s)
R-Loop Structures , RNA , Animals , DNA/genetics , Immunoglobulin Class Switching/genetics , Immunoprecipitation , Mammals/genetics , RNA/genetics
13.
DNA Repair (Amst) ; 110: 103271, 2022 02.
Article in English | MEDLINE | ID: mdl-34990960

ABSTRACT

Activation-induced deaminase (AID) only deaminates cytosine within single-stranded DNA. Transcription is known to increase AID deamination on duplex DNA substrates during transcription. Using a purified T7 RNA polymerase transcription system, we recently found that AID deamination of a duplex DNA substrate is reduced if RNase A is added during transcription. This finding prompted us to consider that the mRNA tail may contribute to AID action at the nearby transcribed strand (TS) or non-transcribed strand (NTS) of DNA, which are transiently single-stranded in the wake of RNA polymerase movement. Here, we used a purified system to test whether a single-stranded oligonucleotide (oligo) consisting of RNA in the 5' portion and DNA in the 3' portion (i.e., 5'RNA-DNA3', also termed an RNA-DNA fusion substrate) could be deaminated equally efficiently as the same sequence when it is entirely DNA. We found that AID acts on the RNA-DNA fusion substrate and the DNA-only substrate with similar efficiency. Based on this finding and our recent observation on the importance of the mRNA tail, we propose a model in which the proximity and length of the mRNA tail provide a critical site for AID loading to permit a high local collision frequency with the NTS and TS in the transient wake of the RNA polymerase. When the mRNA tail is not present, we know that AID action drops to levels equivalent to when there is no transcription at all. This mRNA tether model explains several local and global features of Ig somatic hypermutation and Ig class switch recombination, while integrating structural and functional features of AID.


Subject(s)
Cytidine Deaminase , Somatic Hypermutation, Immunoglobulin , Cytidine Deaminase/chemistry , Cytidine Deaminase/genetics , DNA/genetics , Immunoglobulin Class Switching , RNA , RNA, Messenger/genetics
14.
Org Biomol Chem ; 19(15): 3374-3378, 2021 04 26.
Article in English | MEDLINE | ID: mdl-33899899

ABSTRACT

Proteoglycans (PGs) play important roles in many biological processes including tumor progression, cell adhesion, and regulation of growth factor activities. With glycosaminoglycan chains attached to the core proteins in nature, PGs are highly challenging synthetic targets due to the difficulties in integrating the sulfated glycans with the peptide backbone. To expedite the synthesis, herein, the utility of human xylosyltransferase I (XT-I), the enzyme responsible for initiating PG synthesis, has been explored. XT-I was found to be capable of efficiently installing the xylose unit onto a variety of peptide structures on mg scales. Furthermore, an unnatural sugar, i.e., 6-azidoglucose can be transferred by XT-I introducing a reactive handle onto the glycopeptide for selective functionalization. XT-I can be coupled with ß-4-galactosyl transferase-7 for one pot synthesis of glycopeptides bearing galactose-xylose disaccharide, paving the way toward efficient chemoenzymatic synthesis of PG glycopeptides and glycoproteins.


Subject(s)
Pentosyltransferases/metabolism , Proteoglycans/biosynthesis , Humans , Protein Conformation , Proteoglycans/chemistry , UDP Xylose-Protein Xylosyltransferase
16.
Mol Cell Biol ; 40(16)2020 07 29.
Article in English | MEDLINE | ID: mdl-32513818

ABSTRACT

Activation-induced cytidine deaminase (AID) initiates immunoglobulin (Ig) class switch recombination (CSR), somatic hypermutation (SHM), and gene conversion by converting DNA cytosines to uracils at specific genomic regions. In this study, we examined AID footprints across the entire length of an engineered switch region in cells ablated for uracil repair. We found that AID deamination occurs predominantly at WRC hot spots (where W is A or T and R is A or G) and that the deamination frequency remains constant across the entire switch region. Importantly, we analyzed monoallelic AID deamination footprints on both DNA strands occurring within a single cell cycle. We found that AID generates few and mostly isolated uracils in the switch region, although processive AID deaminations are evident in some molecules. The frequency of molecules containing deamination on both DNA strands at the acceptor switch region correlates with the class switch efficiency, raising the possibility that the minimal requirement for DNA double-strand break (DSB) formation is as low as even one AID deamination event on both DNA strands.


Subject(s)
B-Lymphocytes/cytology , Cytosine/metabolism , Immunoglobulin Class Switching/immunology , Somatic Hypermutation, Immunoglobulin/immunology , Animals , Cytidine Deaminase/metabolism , DNA/metabolism , DNA Breaks, Double-Stranded , Deamination/immunology , Recombination, Genetic/genetics
17.
Crit Rev Biochem Mol Biol ; 54(4): 333-351, 2019 08.
Article in English | MEDLINE | ID: mdl-31509023

ABSTRACT

Immunoglobulin (Ig) class switch recombination (CSR) is the gene rearrangement process by which B lymphocytes change the Ig heavy chain constant region to permit a switch of Ig isotype from IgM to IgG, IgA, or IgE. At the DNA level, CSR occurs via generation and joining of DNA double strand breaks (DSBs) at intronic switch regions located just upstream of each of the heavy chain constant regions. Activation-induced deaminase (AID), a B cell specific enzyme, catalyzes cytosine deaminations (converting cytosines to uracils) as the initial DNA lesions that eventually lead to DSBs and CSR. Progress on AID structure integrates very well with knowledge about Ig class switch region nucleic acid structures that are supported by functional studies. It is an ideal time to review what is known about the mechanism of Ig CSR and its relation to somatic hypermutation. There have been many comprehensive reviews on various aspects of the CSR reaction and regulation of AID expression and activity. This review is focused on the relation between AID and switch region nucleic acid structures, with a particular emphasis on R-loops.


Subject(s)
Cytidine Deaminase/genetics , Cytidine Deaminase/metabolism , Immunoglobulin Class Switching/genetics , Immunoglobulin Switch Region/genetics , Recombination, Genetic , Somatic Hypermutation, Immunoglobulin/genetics , Animals , B-Lymphocytes/metabolism , DNA/genetics , DNA/metabolism , DNA Breaks, Double-Stranded , Humans , Immunoglobulins/genetics , R-Loop Structures/genetics , Translocation, Genetic
18.
J Environ Manage ; 239: 96-102, 2019 Jun 01.
Article in English | MEDLINE | ID: mdl-30889523

ABSTRACT

The recalcitrance of green waste, caused by its high lignocellulose content, is a technical challenge for accelerating green waste composting. However, because lignocellulose degradation in litter (similar to green waste) can be promoted during the freeze-thaw season, and the composting is difficult to implement in this period (due to the low temperature); seasonal freeze-thaw was intended to be used as a pretreatment strategy for the existing technical challenge in the winter of cold regions. In this process, green waste was pretreated with seasonal freeze-thaw to enhance its lignocellulose degradation for subsequent composting. To verify this assumption, two strategies for the pretreatment were used: the green waste was either drenched or immersed in water during the freeze-thaw season, and the effects on subsequent composting were evaluated. The results demonstrated that both strategies can significantly promote the mineralization of TOC (total organic carbon, by 2.73%-8.01% compared with the control, the following comparisons were all based on the control), TN (total nitrogen, by 0.21%-0.52%), and lignocellulose (lignin degradation was promoted by 3.52%-3.73%, cellulose degradation was promoted by 13.23%-14.26%) during composting and that the synthesis of humus was also enhanced (by 19.19%-21.43%). Furthermore, since the loss of NH4+N and NO3-N was significantly less in the drenched treatment than in the immersed treatment (by 9.15% for the loss of NH4+N and 7.66% for the loss of NO3-N), drenching the green waste during the freeze-thaw season might be a better strategy than immersing for nitrogen conservation. An additional advantage of drenching compared to immersing is water conservation.


Subject(s)
Composting , Freezing , Nitrogen , Seasons , Soil , Temperature
19.
J Biol Chem ; 294(13): 5198-5207, 2019 03 29.
Article in English | MEDLINE | ID: mdl-30705092

ABSTRACT

The base excision repair (BER) pathway is an important DNA repair pathway and is essential for immune responses. In fact, it regulates both the antigen-stimulated somatic hypermutation (SHM) process and plays a central function in the process of class switch recombination (CSR). For both processes, a central role for apurinic/apyrimidinic endonuclease 1 (APE1) has been demonstrated. APE1 acts also as a master regulator of gene expression through its redox activity. APE1's redox activity stimulates the DNA-binding activity of several transcription factors, including NF-κB and a few others involved in inflammation and in immune responses. Therefore, it is possible that APE1 has a role in regulating the CSR through its function as a redox coactivator. The present study was undertaken to address this question. Using the CSR-competent mouse B-cell line CH12F3 and a combination of specific inhibitors of APE1's redox (APX3330) and repair (compound 3) activities, APE1-deficient or -reconstituted cell lines expressing redox-deficient or endonuclease-deficient proteins, and APX3330-treated mice, we determined the contributions of both endonuclease and redox functions of APE1 in CSR. We found that APE1's endonuclease activity is essential for IgA-class switch recombination. We provide evidence that the redox function of APE1 appears to play a role in regulating CSR through the interleukin-6 signaling pathway and in proper IgA expression. Our results shed light on APE1's redox function in the control of cancer growth through modulation of the IgA CSR process.


Subject(s)
DNA-(Apurinic or Apyrimidinic Site) Lyase/metabolism , Immunoglobulin A/genetics , Immunoglobulin Class Switching , Animals , B-Lymphocytes/metabolism , Cell Line , DNA Repair , Humans , Interleukin-6/metabolism , Mice , Mice, Inbred C57BL , Oxidation-Reduction , Signal Transduction
20.
Waste Manag ; 79: 443-453, 2018 Sep.
Article in English | MEDLINE | ID: mdl-30343774

ABSTRACT

The aims of this study are to determine the feasibility of applying QROD (quadratic regression orthogonal design) to optimize a combination of microorganisms and to develop a composite inoculum for promoting lignocellulose degradation during GWC (green waste composting). This feasibility was studied in a laboratory scale experiment, using three lignocellulolytic microorganisms, isolated from the mature phase of GWC by the dilution plating method. After the feasibility was confirmed, a composite inoculum was developed through the results of the optimization, whose effect was evaluated by comparing it with Phanerochaete chrysosporium and EM (Effective Microorganisms) in a pilot scale experiment of GWC. The use of QROD to finish this optimization was proven feasible, because the p value of the regression equation was less than 0.05 (0.0108), meaning that the quadratic regression model is suitable for describing the relationship between the combination of the three microorganisms and their ability to degrade lignocellulose. Additional proof of this feasibility is that the composite inoculum in the quadratic regression orthogonal experiment demonstrated lignocellulose degradation ability similar to the GWC experiment. Although the lignin degradation ability of the composite inoculum did not surpass Phanerochaete chrysosporium, it was stronger than EM. Meanwhile, cellulose degradation ability and humus synthesis ability of the composite inoculum were stronger than for Phanerochaete chrysosporium and were close to EM. It is hard to tell which inoculum is the best since each inoculum had advantages in different aspects, while the composite inoculum still showed a considerable effect of lignocellulose degradation during GWC.


Subject(s)
Composting , Phanerochaete , Biodegradation, Environmental , Lignin
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