RESUMEN

Sarcasm is a sophisticated figurative language that is prevalent on social media platforms. Automatic sarcasm detection is significant for understanding the real sentiment tendencies of users. Traditional approaches mostly focus on content features by using lexicon, n-gram, and pragmatic feature-based models. However, these methods ignore the diverse contextual clues that could provide more evidence of the sarcastic nature of sentences. In this work, we propose a Contextual Sarcasm Detection Model (CSDM) by modeling enhanced semantic representations with user profiling and forum topic information, where context-aware attention and a user-forum fusion network are used to obtain diverse representations from distinct aspects. In particular, we employ a Bi-LSTM encoder with context-aware attention to obtain a refined comment representation by capturing sentence composition information and the corresponding context situations. Then, we employ a user-forum fusion network to obtain the comprehensive context representation by capturing the corresponding sarcastic tendencies of the user and the background knowledge about the comments. Our proposed method achieves values of 0.69, 0.70, and 0.83 in terms of accuracy on the Main balanced, Pol balanced and Pol imbalanced datasets, respectively. The experimental results on a large Reddit corpus, SARC, demonstrate that our proposed method achieves a significant performance improvement over state-of-art textual sarcasm detection methods.

RESUMEN

Mainstream partial-denitrification with anammox (PD-anammox) process faced the challenge of complex organics involved in real sewage. Herein, PD-anammox coupled with in-situ fermentation was successfully achieved in a full biofilm system formed by three-stage anoxic/oxic reactor to treat real wastewater with low COD/N of 3.6. The total nitrogen (TN) removal efficiency was enhanced to 78.4% ± 3.6% with average TN and ammonium concentrations in effluent of 10.6 and 0.5 mg N/L, respectively. Batch tests confirmed that partial-denitrification was the major nitrite provider for anammox in the anoxic biofilm, while in-situ fermentation could decompose the complex organics to readily-biodegradable organics for full- or partial-denitrification. Additionally, a significant anammox bacteria (Candidatus Brocadia) population was detected in the second (3.53%) and third (4.46%) anoxic zones, while denitrifiers and fermentative bacteria were mainly enriched in the first anoxic zone. This study presents a feasible approach for PD-anammox process in practical application under mainstream condition.

Asunto(s)

Compuestos de Amonio , Aguas Residuales , Oxidación Anaeróbica del Amoníaco , Biopelículas , Reactores Biológicos , Desnitrificación , Fermentación , Nitrógeno , Oxidación-Reducción , Aguas del Alcantarillado

RESUMEN

Hydroxylamine (NH2OH) as the putative intermediate for anammox ensures the robustness of partial nitritation/anammox (PN/A) process; however, the feasible for NH2OH addition to improve the stability of PN/A process under low-strength ammonia (NH4+-N) condition need to be further investigated. In this study, the restoration and steady operation of mainstream PN/A process were investigated to treat real sewage with in situ NH2OH added in a continuous alternating anoxic/aerobic with integrated fixed-film activated sludge (A3-IFAS) reactor. Results showed that the deteriorated PN/A process caused by nitrate (NO3--N) built-up was rapidly restored with a distinct decrease of the NO3--Nproduced/NH4+-Nconsumed ratio from 28.7% to <10.0% within 20 days, after 5 mg N/L of NH2OH was added daily into the aerobic zone of A3-IFAS reactor. After 230 days of operation, the average total nitrogen (TN) and phosphate (PO43--P) removal efficiencies of 80.8% and 91.5%, respectively were stably achieved, with average effluent sCOD, NH4+-N, TN and PO43--P concentrations reaching 23.1, 2.3, 7.7 and 0.4 mg/L, respectively. Microbial community characterization revealed Candidatus Brocadia (3.60% and 2.92%) and Ignavibacteriae (1.56% and 2.66%) as the dominant anammox bacteria and denitrifying bacteria, respectively, jointly attached in the biofilm_1 and biofilm_2, while Candidatus Microthrix (5.17%) dominant in floc sludge was main responsible for phosphorus removal. This study confirmed that NH2OH addition is an effective strategy for nitrite-oxidizing bacteria suppression, contributing to the in situ restoration of PN/A process and high stable mainstream nitrogen and phosphorus removal in a continuous PN/A process from real sewage.

Asunto(s)

Compuestos de Amonio , Aguas del Alcantarillado , Reactores Biológicos , Desnitrificación , Hidroxilamina , Hidroxilaminas , Nitrógeno , Oxidación-Reducción , Fósforo , Aguas Residuales

RESUMEN

Dual oxidases (DUOXs) were originally identified as NADPH oxidases (NOXs), found to be associated with the reactive oxygen species (ROS) hydrogen peroxide (H2O2) production at the plasma membrane and crucial in host biological processes. In this study, SpDUOX1 and SpDUOX2 of mud crab (Scylla paramamosain) were identified and studied. Both SpDUOX1 and SpDUOX2 are transmembrane proteins, including an N-signal peptide region and a peroxidase homology domain in the extracellular region, transmembrane regions, and three EF (calcium-binding region) domains, a FAD-binding domain, and a NAD binding domain in the intracellular region. The SpDUOXs were expressed in all tissues examined, but mainly in hepatopancreas, heart, and mid-intestine. The expression of the SpDUOXs in the hemolymph of mud crabs was up-regulated after challenge with Vibrio parahemolyticus or LPS. RNA interference (RNAi) of the SpDUOXs resulted in reduced ROS production in hemolymph. The bacterial count increased in the hemolymph of mud crabs injected with SpDUOX1 or SpDUOX2-RNAi, while the bacterial clearance ability of hemolymph significantly reduced. At the phylum level, the phyla Bacteroidetes and Actinobacteria were significantly increased, while Proteobacteria were significantly reduced following SpDUOX2 knockdown. There was a significant increase in the relative abundance of the genera Marinomonas, Pseudoalteromonas, Shewanella, and Hydrogenoph in SpDUOX2 depleted mud crabs compared with the controls. Our current findings therefore indicated that SpDUOXs might play important roles in maintaining the homeostasis in the hemolymph microbiota of mud crab.

Asunto(s)

Proteínas de Artrópodos/metabolismo , Braquiuros/enzimología , Braquiuros/microbiología , Oxidasas Duales/metabolismo , Hemolinfa/enzimología , Hemolinfa/microbiología , Microbiota/fisiología , Animales , Proteínas de Artrópodos/antagonistas & inhibidores , Proteínas de Artrópodos/genética , Carga Bacteriana , Braquiuros/inmunología , Oxidasas Duales/antagonistas & inhibidores , Oxidasas Duales/genética , Técnicas de Silenciamiento del Gen , Hemolinfa/inmunología , Homeostasis , Microbiota/inmunología , Filogenia , Especies Reactivas de Oxígeno/metabolismo

RESUMEN

CheA-short interacts with CheZ to localize CheZ to cell poles. The fifth helical region (residues 112 to 133) from the phosphotransfer domain of CheA interacts with CheZ and becomes ordered and helical, although it lacks a stable fold in the CheA fragment comprising residues 98 to 150 alone. One CheA molecule binds to one CheZ dimer.

Asunto(s)

Proteínas Bacterianas , Quimiotaxis , Escherichia coli/metabolismo , Proteínas de la Membrana , Proteínas Bacterianas/química , Proteínas Bacterianas/metabolismo , Sitios de Unión , Quimiotaxis/genética , Dimerización , Escherichia coli/genética , Proteínas de Escherichia coli , Histidina Quinasa , Espectroscopía de Resonancia Magnética , Proteínas de la Membrana/química , Proteínas de la Membrana/metabolismo , Proteínas Quimiotácticas Aceptoras de Metilo , Modelos Moleculares , Isótopos de Nitrógeno , Fosforilación , Unión Proteica , Estructura Terciaria de Proteína , Protones , Transducción de Señal

RESUMEN

alpha-Synuclein is a major component of Lewy bodies in Parkinson's disease. Although no signal sequence is apparent, alpha-synuclein expressed in Escherichia coli is mostly located in the periplasm. The possibilities that alpha-synuclein translocated into the periplasm across the inner membrane by the SecA or the Tat targeting route identified in bacteria and that alpha-synuclein was released through MscL were excluded. The signal recognition particle-dependent pathway is involved in the translocation of alpha-synuclein. The C-terminal 99-to-140 portion of the alpha-synuclein molecule plays a signal-like role for its translocation into the periplasm, cooperating with the central 61-to-95 section. The N-terminal 1-to-60 region is not required for this translocation.

Asunto(s)

Escherichia coli/genética , alfa-Sinucleína/metabolismo , Traslocación Bacteriana/fisiología , Membrana Celular/metabolismo , Humanos , Fragmentos de Péptidos/metabolismo , Plásmidos , Transporte de Proteínas , Proteínas Recombinantes/metabolismo , Tripsina , alfa-Sinucleína/genética

RESUMEN

alpha-Synuclein (AS) is a main component of Lewy bodies in midbrain dopamine neurons pathologically characteristic of Parkinson's disease. We show that heat shock protein (Hsp) 70 inhibits AS fibril formation via preventing the formation of prefibrillar AS (PreAS), binding with PreAS to impede nuclei formation, and binding with nuclei to retard fibril elongation. Also, Hsp70 suppresses the PreAS-induced permeabilization of vesicular membrane through interactions with PreAS. The substrate-binding domain alone is sufficient for Hsp70 to inhibit AS fibril formation. The binding of Hsp70 with PreAS only requires the substrate-binding subdomain, and the binding with AS nuclei requires the C-terminal lid subdomain as well. The results may form the molecular basis for elucidating the mechanism of AS fibril formation and the crucial roles of chaperones in protecting proteins from toxic conversion in many conformational diseases.

Asunto(s)

Proteínas HSP70 de Choque Térmico/química , alfa-Sinucleína/química , Humanos , Liposomas/química , Permeabilidad , Unión Proteica , Estructura Terciaria de Proteína

RESUMEN

Escherichia coli DnaJ, possessing both chaperone and thiol-disulfide oxidoreductase activities, is a homodimeric Hsp40 protein. Each subunit contains four copies of a sequence of -CXXCXGXG-, which coordinate with two Zn(II) ions to form an unusual topology of two C4-type zinc fingers, C144DVC147Zn(II)C197NKC200 (Zn1) and C161PTC164Zn(II)C183PHC186 (Zn2). Studies on five DnaJ mutants with Cys in Zn2 replaced by His or Ser (C183H, C186H, C161H/C183H, C164H/183H, and C161S/C164S) reveal that substitutions of one or two Cys residues by His or Ser have little effect on the general conformation and association property of the molecule. Replacement of two Cys residues by His does not interfere with the zinc coordination. However, replacement of two Cys by Ser results in a significant decrease in the proportion of coordinated Zn(II), although the unique zinc finger topology is retained. The mutants of C183H, C186H, and C161S/C164S display full disulfide reductase activity of wild-type DnaJ, while C161H/C183H and C164H/183H exhibit severe defect in the activity. All of the mutations do not substantially affect the chaperone activity. The results indicate that the motif of -CXXC- is critical to form an active site and indispensable to the thiol-disulfide oxidoreductase activity of DnaJ. Each -CXXC- motif in Zn2 but not in Zn1 functions as an active site.

Asunto(s)

Cisteína/química , Proteínas de Escherichia coli/química , Proteínas de Choque Térmico/química , Proteína Disulfuro Reductasa (Glutatión)/química , Dedos de Zinc , Secuencias de Aminoácidos/genética , Secuencia de Aminoácidos , Sustitución de Aminoácidos/genética , Sitios de Unión/genética , Catálisis , Cisteína/genética , Proteínas de Escherichia coli/genética , Proteínas de Escherichia coli/metabolismo , Proteínas del Choque Térmico HSP40 , Proteínas de Choque Térmico/genética , Proteínas de Choque Térmico/metabolismo , Histidina/genética , Chaperonas Moleculares/química , Chaperonas Moleculares/genética , Chaperonas Moleculares/metabolismo , Datos de Secuencia Molecular , Fragmentos de Péptidos/química , Fragmentos de Péptidos/genética , Fragmentos de Péptidos/metabolismo , Conformación Proteica , Proteína Disulfuro Reductasa (Glutatión)/genética , Proteína Disulfuro Reductasa (Glutatión)/metabolismo , Estructura Terciaria de Proteína/genética , Serina/genética , Zinc/química , Dedos de Zinc/genética

RESUMEN

Thioredoxin, DsbA, the N-terminal active-site domain a and the non-active-site domain b of protein-disulfide isomerase are all monomeric with a thioredoxin fold, and each exhibits low or no isomerase and chaperone activity. We have linked the N terminus of the above four monomers, individually, to the C terminus of the N-terminal domain of DsbC via the flexible linker helix of the latter to produce four domain hybrids, DsbCn-Trx, DsbCn-DsbA, DsbCn-PDIa, and DsbCn-PDIb. These four hybrid proteins form homodimers, and except for DsbCn-PDIb they exhibit new or greatly elevated isomerase as well as chaperone activity. Three-dimensional structure prediction indicates that all the four domain hybrids adopt DsbC-like V-shaped structure with a broad uncharged cleft between the two arms for binding of non-native protein folding intermediates. The results provide strong evidence that dimerization creates chaperone and isomerase activity for monomeric thiol-protein oxidases or reductases, and suggesting a pathway for proteins to acquire new functions and/or higher biological efficiency during evolution.

Asunto(s)

Chaperonas Moleculares/química , Sitios de Unión , Dicroismo Circular , Dimerización , Electroforesis en Gel de Poliacrilamida , Escherichia coli/metabolismo , Guanidina/química , Modelos Moleculares , Plásmidos/metabolismo , Unión Proteica , Conformación Proteica , Proteína Disulfuro Isomerasas/química , Pliegue de Proteína , Estructura Terciaria de Proteína , Tiorredoxinas/química , Factores de Tiempo

RESUMEN

Hydantoin-utility-enzyme is widely used in enzymic production of various amino acids. One of its component, carbamoylase, is responsible for the conversion of N-carbamylamino acids to corresponding amino acids, which is crucial for the stereoselectivity and rate limiting. To improve the production of the enzyme, an L-N-carbamoylase gene from Arthrobacter BT801, a hydantoinase producting strain being able to convert 5-benzylhydantoin to phenylalanine, was cloned into E. coli. The gene was highly expressed in E. coli M15 under control of T5 promoter. A protein band about 44kD was detected by SDS-PAGE in the recombinant cell lysate. The objective product, which is principally in soluble form, represented 40% of total cell protein. The N-carbamoylase specific activity of the recombinant M15/pQE60- hyuC is 53 times higher than that of Arthrobacter BT801. The total biotransformation activity increased 8.1 times when. M15/pQE60-hyuC was added into the Arthrobacter BT801 reaction system. The successful expression of the enzyme is significant for the application of the hydantoinase producing strain or the enzyme thereof.

Asunto(s)

Amidohidrolasas/metabolismo , Arthrobacter/genética , Escherichia coli/metabolismo , Amidohidrolasas/genética , Arthrobacter/enzimología , Electroforesis en Gel de Poliacrilamida , Escherichia coli/genética , Vectores Genéticos/genética , Hidantoínas/metabolismo , Modelos Genéticos , Fenilalanina/metabolismo , Plásmidos/genética , Reacción en Cadena de la Polimerasa

RESUMEN

Hydantoinase can be widely used in enzymic production of various amino acids. In order to obtain the hydantoinase genes in Arthrobacter BT801, its chromatosomal DNA is isolated and partialy digested with Sau3A I to collect fragments of about 30kb. Then, this fragment is inserted into the Hpa I and Pst I site of cosmid pKC505. The genomic library was thus constructed by packing in vitro with lambda phage package protein and transfecting E. coli DH5alpha. A positive transformant was selected from the library using thin layer chromatography and other methods. A DNA fragment containing complete hydantoinase genes was sequenced by sub-cloning into pUC18. The gene can express active protein under control of its own promoter and T5 promoter in E. coli. The isolation of the gene established foundition for research and application of the hydantoinase.

Asunto(s)

Amidohidrolasas/aislamiento & purificación , Amidohidrolasas/metabolismo , Arthrobacter/genética , Biblioteca de Genes , Amidohidrolasas/genética , Bacteriófago lambda/genética , Cromatografía en Capa Delgada , Clonación Molecular , Electroforesis en Gel de Agar , Electroforesis en Gel de Poliacrilamida , Escherichia coli/genética , Escherichia coli/metabolismo , Regiones Promotoras Genéticas/genética

RESUMEN

The effects of applying nitrogen fertilizer in ploughed furrow at different stages on dry matter production and yield of rice were studied in a field experiment in 1999. The results showed that applying N fertilizer at booting stage (BS) had better effects on dry weight (2.9 g.hill-1) of leaf, stem and whole plant than at panicle primordia formation stage (PPFS), tillering stage (TS) and regular N fertilization (RF). Meanwhile, the dry weight of leaf and sheath as well as the leaf area index (LAI, 8.9) could be maintained at a high level for a relative long time in BS treatment, compared with PPFS, TS and RF treatments. Similar phenomenon was observed in the growth velocity (0.73 g.d-1.hill-1) of stem and whole plant, and the dry weight (10434 kg.hm-2) of seed. The grain yield of rice followed the sequence of BS > or = PPFS > TS > or = RF. Thus, the optimum stage of applying N fertilizer in ploughed furrow was the booting stage.

Asunto(s)

Fertilizantes , Nitrógeno/química , Oryza/fisiología , Agricultura , Productos Agrícolas

RESUMEN

The hydantoinase-producing conditions from strain Arthrobacter K1108 were investigated. It is shown that the hydantoinase in the strain is intracellular and inducible. Its optimal inducer is 5-benzylhydantoin, while 5-indolylmethylhydantoin and 5-phenylhydantoin cannot induce the production of hydantoinase in K1108. A gratuitous inducer was designed, with which the hydantoinase production is 343% as much as that with 5-benzylhydantoin. The media for culturing the bacteria were screened and optimized. Under optimal conditions, the specific activity of K1108 cells reached 10.8 U/mL.

Asunto(s)

Amidohidrolasas/biosíntesis , Arthrobacter/enzimología , Hidantoínas/farmacología , Arthrobacter/citología , Técnicas de Cultivo de Célula , Medios de Cultivo