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1.
J Proteome Res ; 23(3): 929-938, 2024 Mar 01.
Artículo en Inglés | MEDLINE | ID: mdl-38225219

RESUMEN

Mass spectrometry (MS) is a valuable tool for plasma proteome profiling and disease biomarker discovery. However, wide-ranging plasma protein concentrations, along with technical and biological variabilities, present significant challenges for deep and reproducible protein quantitation. Here, we evaluated the qualitative and quantitative performance of timsTOF HT and timsTOF Pro 2 mass spectrometers for analysis of neat plasma samples (unfractionated) and plasma samples processed using the Proteograph Product Suite (Proteograph) that enables robust deep proteomics sampling prior to mass spectrometry. Samples were evaluated across a wide range of peptide loading masses and liquid chromatography (LC) gradients. We observed up to a 76% increase in total plasma peptide precursors identified and a >2-fold boost in quantifiable plasma peptide precursors (CV < 20%) with timsTOF HT compared to Pro 2. Additionally, approximately 4.5 fold more plasma peptide precursors were detected by both timsTOF HT and timsTOF Pro 2 in the Proteograph analyzed plasma vs neat plasma. In an exploratory analysis of 20 late-stage lung cancer and 20 control plasma samples with the Proteograph, which were expected to exhibit distinct proteomes, an approximate 50% increase in total and statistically significant plasma peptide precursors (q < 0.05) was observed with timsTOF HT compared to Pro 2. Our data demonstrate the superior performance of timsTOF HT for identifying and quantifying differences between biologically diverse samples, allowing for improved disease biomarker discovery in large cohort studies. Moreover, researchers can leverage data sets from this study to optimize their liquid chromatography-mass spectrometry (LC-MS) workflows for plasma protein profiling and biomarker discovery. (ProteomeXchange identifier: PXD047854 and PXD047839).


Asunto(s)
Proteínas Sanguíneas , Proteoma , Humanos , Reproducibilidad de los Resultados , Péptidos , Biomarcadores
2.
New Phytol ; 240(3): 1246-1258, 2023 11.
Artículo en Inglés | MEDLINE | ID: mdl-37668195

RESUMEN

Biocrusts are phototroph-driven communities inhabiting arid soil surfaces. Like plants, most photoautotrophs (largely cyanobacteria) in biocrusts are thought to exchange fixed carbon for essential nutrients like nitrogen with cyanosphere bacteria. Here, we aim to compare beneficial interactions in rhizosphere and cyanosphere environments, including finding growth-promoting strains for hosts from both environments. To examine this, we performed a retrospective analysis of 16S rRNA gene sequencing datasets, host-microbe co-culture experiments between biocrust communities/biocrust isolates and a model grass (Brachypodium distachyon) or a dominant biocrust cyanobacterium (Microcoleus vaginatus), and metabolomic analysis. All 18 microbial phyla in the cyanosphere were also present in the rhizosphere, with additional 17 phyla uniquely found in the rhizosphere. The biocrust microbes promoted the growth of the model grass, and three biocrust isolates (Bosea sp._L1B56, Pseudarthrobacter sp._L1D14 and Pseudarthrobacter picheli_L1D33) significantly promoted the growth of both hosts. Moreover, pantothenic acid was produced by Pseudarthrobacter sp._L1D14 when grown on B. distachyon exudates, and supplementation of plant growth medium with this metabolite increased B. distachyon biomass by over 60%. These findings suggest that cyanobacteria and other diverse photoautotrophic hosts can be a source for new plant growth-promoting microbes and metabolites.


Asunto(s)
Plantas , Rizosfera , ARN Ribosómico 16S/genética , Estudios Retrospectivos , Biomasa , Suelo , Microbiología del Suelo
3.
Org Biomol Chem ; 21(33): 6750-6756, 2023 Aug 23.
Artículo en Inglés | MEDLINE | ID: mdl-37554009

RESUMEN

An external oxidant free Ru(II)-catalyzed C-H activation followed by an intermolecular annulation between oximes and sulfoxonium ylides has been developed. This transformation proceeds smoothly with a broad range of substrates, affording a series of isoquinoline derivatives in moderate to good yields. This protocol was successfully applied to the synthesis of moxaverine.

4.
Cell Mol Biol (Noisy-le-grand) ; 69(10): 222-226, 2023 Oct 31.
Artículo en Inglés | MEDLINE | ID: mdl-37953559

RESUMEN

Aortic Dissection (AD) is a cardiovascular emergency with high mortality, of which one feature is the phenotypic switch of vascular smooth muscle cells (VSMCs). Transient Receptor Potential Channel Interacting (PKD1) has been regarded as one regulator as well as one biomarker for AD. However, multiple candidate pathways were reported though which PKD1 regulates AD in previous study, a comprehensive insight is still absent. In this study, we compared the AD and normal samples in transcriptome scale, and detected 717 PKD1-related differential expressed genes, which enriched in mitogen-activated protein kinase (MAPK) signal transduction (AD tissue preference) and VSMC contraction pathway (normal tissue preference). Furthermore, we also found two important functional hub genes in PKD1 regulation, JUN and ACTN2, and established a carnal-miRNA-mRNA network. Our study demonstrated the co-regulation of muscle development and signal transduction in AD's progression, and also provided the genetic basis for the following mechanism research with AD.


Asunto(s)
Disección Aórtica , MicroARNs , Humanos , Músculo Liso Vascular/metabolismo , Proteínas Quinasas Activadas por Mitógenos/genética , Proteínas Quinasas Activadas por Mitógenos/metabolismo , Transducción de Señal , Disección Aórtica/genética , MicroARNs/genética , MicroARNs/metabolismo , Miocitos del Músculo Liso/metabolismo , Células Cultivadas
5.
BMC Cardiovasc Disord ; 23(1): 147, 2023 03 23.
Artículo en Inglés | MEDLINE | ID: mdl-36959563

RESUMEN

BACKGROUND: Aortic dissection (AD) is a rare disease with severe morbidity and high mortality. Presently, the pathogenesis of aortic dissection is still not completely clear, and studying its pathogenesis will have important clinical significance. METHODS: We downloaded 28 samples from the Gene Expression Omnibus (GEO) database (Accession numbers: GSE147026 and GSE190635), including 14 aortic dissection samples and 14 healthy controls (HC) samples. The Limma package was used to screen differentially expressed genes. The StarBasev2.0 tool was used to predict the upstream molecular circRNA of the selected miRNAs, and Cytoscape software was used to process the obtained data. STRING database was used to analyze the interacting protein pairs of differentially expressed genes under medium filtration conditions. The R package "org.hs.eg.db" was used for functional enrichment analysis. RESULTS: Two hundred genes associated with aortic dissection were screened. Functional enrichment analysis was performed based on these 200 genes. At the same time, 2720 paired miRNAs were predicted based on these 200 genes, among which hsa-miR-650, hsa-miR-625-5p, hsa-miR-491-5p and hsa-miR-760 paired mRNAs were the most. Based on these four miRNAs, 7106 pairs of circRNAs were predicted to be paired with them. The genes most related to these four miRNAs were screened from 200 differentially expressed genes (CDH2, AKT1, WNT5A, ADRB2, GNAI1, GNAI2, HGF, MCAM, DKK2, ISL1). CONCLUSIONS: The study demonstrates that miRNA-associated circRNA-mRNA networks are altered in AD, implying that miRNA may play a crucial role in regulating the onset and progression of AD. It may become a potential biomarker for the diagnosis and treatment of AD.


Asunto(s)
MicroARNs , ARN Circular , Humanos , ARN Circular/genética , MicroARNs/genética , MicroARNs/metabolismo , ARN Mensajero/genética , ARN Mensajero/metabolismo , Biomarcadores , Bases de Datos Factuales , Redes Reguladoras de Genes
6.
Retina ; 43(10): 1816-1819, 2023 10 01.
Artículo en Inglés | MEDLINE | ID: mdl-37721726

RESUMEN

PURPOSE: Allogenic transplantation of retinal pigmented epithelium monolayer sheet has experienced bottlenecks due to imperfect surgical techniques. In this study, we developed a novel approach for allogenic transplantation of big sheets of retinal pigment epithelium (RPE)-Bruch membrane complex. METHODS: RPE-Bruch membrane complex sheets of 5 × 6 mm2 to 10 × 10 mm2 were taken from donated eyes. Through a novel approach, the sheets of RPE-Bruch membrane complex were transplanted into the subretinal space of eight eyes (8 patients) with late-stage retinitis pigmentosa. The patients were followed up for 5 ± 2 months. RESULTS: All RPE-Bruch membrane complexes were successfully inserted into the subretinal space during the surgery. Follow-up examinations also showed that the grafts attached well to the transplantation site. No rejection or retinal detachment was found. CONCLUSION: Through our technique, big sheets of allogenic RPE-Bruch membrane complexes could be implanted into the subretinal space smoothly. This novel approach may be useful for big sheet of allogenic RPE-derived or stem cells-derived RPE transplantation in the treatment of RP and other retinal dystrophic diseases.


Asunto(s)
Desprendimiento de Retina , Enfermedades de la Retina , Retinitis Pigmentosa , Humanos , Epitelio Pigmentado de la Retina , Lámina Basal de la Coroides , Desprendimiento de Retina/cirugía , Retinitis Pigmentosa/cirugía
7.
BMC Ophthalmol ; 23(1): 244, 2023 May 31.
Artículo en Inglés | MEDLINE | ID: mdl-37259051

RESUMEN

PURPOSE: To observe long-term prognosis of anterior segment ischemia (ASI) following hyaluronic acid (HA) injection, propose a severity grading system for ASI and a predictive model for phthisis bulbi (PB) based on long-term secretion dysfunction of ciliary process. METHODS: This is a retrospective case-control study. All enrolled 20 patients were divided into two groups and followed for at least 6 months to observe the formation and transformation characteristics of ASI and long-term prognosis based on the degrees of ciliary function damage. RESULTS: The severity of ASI following HA injection could be subdivided into 4 grades according to the degrees of ciliary function damage, comprising ASI grades 0, 1, 2 and 3. In 20 patients, ophthalmoplegia at 1-month follow-up, ASI within 1 month, ASI at 1-month follow-up, hypotony within 6 months were all significantly more common in study group than in control group (60% vs. 0%, P = 0.011; 100% vs. 20%, P = 0.001; 100% vs. 0%, P < 0.001; 80% vs. 0%, P = 0.001, respectively). Sensitivity, specificity and the area under the receiver operating characteristic curve (AUC) for predicting subsequent PB at 2-year follow-up through the co-occurrence of ophthalmoplegia at 1-month follow-up and hypotony within 6 months was 100%, 100% and 1.00, respectively. CONCLUSIONS: The new grading system for ASI and novel predictive model for PB we proposed could predict the long-term prognosis and probability of subsequent PB due to ASI following HA injection through several dynamic assessments within 6 months. LEVEL OF EVIDENCE: Level IV, observational prognostic study.


Asunto(s)
Técnicas Cosméticas , Oftalmopatías , Oftalmoplejía , Humanos , Ceguera , Estudios de Casos y Controles , Técnicas Cosméticas/efectos adversos , Ácido Hialurónico , Estudios Retrospectivos
8.
Bioprocess Biosyst Eng ; 46(5): 761-769, 2023 May.
Artículo en Inglés | MEDLINE | ID: mdl-36801972

RESUMEN

Hydrogen production from dark fermentation has potential application due to its environmental friendliness, low production cost, and sustainability. However, there is still an obstacle to improving the efficiency of bioH2 production to meet the requirements in practical applications. In this research, copper molybdates are synthesized under different pH conditions as additives to study their different influence processes during anaerobic hydrogen production from cotton straws with the pure cultural system. A series of results indicate that CuMoO4 with appropriate experimental conditions has the highest H2 yield at 191.3 mL/g straws at 37 °C, which is 236% higher than the control group. It can be shown that O. ethanolica 8KG-4 has an obvious accompanying with high stability and low cytotoxicity for this clean energy production system as well as the improvement of metabolic pathway. These results extend new thinking of obtaining higher H2 yield as a biofuel in future production.


Asunto(s)
Cobre , Hidrógeno , Anaerobiosis , Fermentación , Hidrógeno/metabolismo
9.
Biochem Biophys Res Commun ; 634: 138-144, 2022 12 17.
Artículo en Inglés | MEDLINE | ID: mdl-36242920

RESUMEN

In recent years, abdominal aortic aneurysm (AAA) lesions have become one of the important diseases that threaten public health. Related studies have confirmed that the occurrence of abdominal aortic aneurysms is related to inflammatory stress, cell apoptosis, and elastic fiber degradation. DDX3x is thought to interact with inflammasomes such as NLRP3 to aggravate the process of the inflammatory response, but its role in the occurrence of AAA remains unclear. Since DDX3x is indispensable in animal embryonic growth, we used an adeno-associated virus to construct gene-overexpressing mice to induce aneurysm development through AngII infusion. The results indicated that the incidence of aneurysms, inflammatory cell infiltration, vascular smooth muscle cell transformation, and oxidative stress levels were significantly increased under the condition of DDX3x overexpression. At the signaling level, activation of the AKT pathway exacerbates aneurysm formation. Taken together, we believe that DDX3x plays a key role in the development of aneurysms and may be a new target for the treatment of aneurysm progression.


Asunto(s)
Aneurisma de la Aorta Abdominal , Ratones , Animales , Aneurisma de la Aorta Abdominal/patología , Ratones Noqueados para ApoE , Aorta Abdominal/patología , Proteínas Proto-Oncogénicas c-akt/metabolismo , Ratones Noqueados , Angiotensina II/metabolismo , Modelos Animales de Enfermedad , Ratones Endogámicos C57BL , ARN Helicasas DEAD-box/genética , ARN Helicasas DEAD-box/metabolismo
10.
Biochem Biophys Res Commun ; 636(Pt 1): 112-120, 2022 12 25.
Artículo en Inglés | MEDLINE | ID: mdl-36332472

RESUMEN

Myocytes undergoing hypoxia condition can recruit macrophages and cause pro-inflammation initiation around the injury area. Mitochondrial dysfunction is related to macrophage pyroptosis. Stomatin-like protein-2 (SLP-2) can regulate mitochondrial biogenesis and function. Whether SLP-2 could affect macrophage pyroptosis remains unclear. In this study, bone marrow derived macrophages (BMDMs) were extracted from WT and SLP-2 knocked out mice, then stimulated by LPS/Nigericin. Western blot showed that SLP-2-/- promoted the expression of NLRP3, GSDMD-N, caspase-11 in macrophages, which means the deficiency of SLP-2 augments macrophage pyroptosis. Higher fluorescence intensity of dihydroethidium and TUNEL represented the increased ROS releasing and macrophage programmed death in SLP-2 deficiency groups. The immunofluorescence intensity of MtioTracker Red decreased and that of mitochondrial ROS (mtROS) increased in SLP-2 deletion groups with LPS/Nigericin stimulation, representing the increased mitochondrial damage. The expression level of HIF-1α increased in SLP-2 deletion macrophages with LPS and Nigericin stimulation. The level of Parkin and the ratio of LC3II/I decreased in SLP-2 deficiency macrophages after stimulated by LPS/Nigericin, compared with untreated macrophages. H9c2 cells were cultured in hypoxia condition before being cocultured with macrophage supernatant. The cocultured H9c2 cells were injured due to the serious pyroptosis of SLP-2 deficiency macrophages. According to these results, we suggest that SLP-2 can reduce macrophage pyroptosis and relieve hypoxia H9c2 cells injury through protecting mitochondrial function.


Asunto(s)
Proteína con Dominio Pirina 3 de la Familia NLR , Piroptosis , Ratones , Animales , Proteína con Dominio Pirina 3 de la Familia NLR/metabolismo , Especies Reactivas de Oxígeno/metabolismo , Lipopolisacáridos/metabolismo , Nigericina , Macrófagos/metabolismo , Mitocondrias/metabolismo , Hipoxia/metabolismo , Inflamasomas/metabolismo
11.
Org Biomol Chem ; 20(4): 783-789, 2022 01 26.
Artículo en Inglés | MEDLINE | ID: mdl-34989388

RESUMEN

The synthesis of isoindolinones from N-methoxy benzamides and saturated ketones via a bimetallic tandem catalytic annulation has been accomplished. The reaction is catalyzed by a Rh/Cu-cocatalytic system and proceeds via the combination of Cu-catalyzed dehydrogenation of ketones and Rh-catalyzed direct C-H functionalization with the assistance of the N-methoxy amide group which also acts as an oxidant to regenerate the Rh catalyst. This method shows good compatibility with a wide range of substrates and functional groups, and provides an alternative strategy to obtain diverse isoindolinones.

12.
Molecules ; 27(4)2022 Feb 21.
Artículo en Inglés | MEDLINE | ID: mdl-35209218

RESUMEN

BACKGROUND: This study aimed to develop an ultrathin nanofibrous membrane able to, firstly, mimic the natural fibrous architecture of human Bruch's membrane (BM) and, secondly, promote survival of retinal pigment epithelial (RPE) cells after surface functionalization of fibrous membranes. METHODS: Integrin-binding peptides (IBPs) that specifically interact with appropriate adhesion receptors on RPEs were immobilized on Bruch's-mimetic membranes to promote coverage of RPEs. Surface morphologies, Fourier-transform infrared spectroscopy spectra, contact angle analysis, Alamar Blue assay, live/dead assay, immunofluorescence staining, and scanning electron microscopy were used to evaluate the outcome. RESULTS: Results showed that coated membranes maintained the original morphology of nanofibers. After coating with IBPs, the water contact angle of the membrane surfaces varied from 92.38 ± 0.67 degrees to 20.16 ± 0.81 degrees. RPE cells seeded on IBP-coated membranes showed the highest viability at all time points (Day 1, p < 0.05; Day 3, p < 0.01; Days 7 and 14, p < 0.001). The proliferation rate of RPE cells on uncoated poly(ε-caprolactone) (PCL) membranes was significantly lower than that of IBP-coated membranes (p < 0.001). SEM images showed a well-organized hexa/polygonal monolayer of RPE cells on IBP-coated membranes. RPE cells proliferated rapidly, contacted, and became confluent. RPE cells formed a tight adhesion with nanofibers under high-magnification SEM. Our findings confirmed that the IBP-coated PCL membrane improved the attachment, proliferation, and viability of RPE cells. In addition, in this study, we used serum-free culture for RPE cells and short IBPs without immunogenicity to prevent graft rejection and immunogenicity during transplantation. CONCLUSIONS: These results indicated that the biomimic BM-IBP-RPE nanofibrous graft might be a new, practicable approach to increase the success rate of RPE cell transplantation.


Asunto(s)
Lámina Basal de la Coroides , Nanofibras , Péptidos , Epitelio Pigmentado de la Retina/trasplante , Ingeniería de Tejidos , Materiales Biocompatibles , Biomimética/métodos , Adhesión Celular , Trasplante de Células , Células Cultivadas , Fenómenos Químicos , Humanos , Integrinas/metabolismo , Nanofibras/química , Nanofibras/ultraestructura , Péptidos/metabolismo , Análisis Espectral
13.
Org Biomol Chem ; 19(26): 5899-5904, 2021 07 07.
Artículo en Inglés | MEDLINE | ID: mdl-34132728

RESUMEN

A direct C2-H thiolation of azoles with Bunte salts was achieved under the combined action of copper and silver salts. This protocol could furnish various substituted 2-thioazoles in moderate to good yields. This method has a broad substrate scope and shows good functional group tolerance.

14.
Heart Lung Circ ; 30(10): 1449-1455, 2021 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-34088631

RESUMEN

Stomatin-like protein-2 (SLP-2) is a mitochondrial-associated protein that is abundant in cardiomyocytes. Many reports have shown that SLP-2 plays an important role in mitochondria. The treatment of mitochondrial cardiomyopathy (MCM) needs further improvement, so the relationship between SLP-2 and MCM is worth exploring. This study reviewed some protective mechanisms of SLP-2 on mitochondria. Published studies have shown that SLP-2 protects mitochondria by stabilising the function of optic atrophy 1 (OPA1), promoting mitofusin (Mfn) 2 expression, interacting with prohibitins and cardiolipin, forming SLP-2-PARL-YME1L (SPY) complex, and stabilising respiratory chain complexes, suggesting that SLP-2 is a new potential target for the treatment of MCM. However, the specific mechanism of SLP-2 needs to be confirmed by further research.


Asunto(s)
Cardiomiopatías , Proteínas de la Membrana , Proteínas Sanguíneas , Cardiomiopatías/tratamiento farmacológico , Humanos , Proteínas de la Membrana/genética , Membranas Mitocondriales , Proteínas Mitocondriales/genética
15.
J Cell Mol Med ; 24(14): 8138-8150, 2020 07.
Artículo en Inglés | MEDLINE | ID: mdl-32529766

RESUMEN

Recently, the first-line anti-diabetic drug metformin shows versatile protective effects against several diseases and is potentially prescribed to healthy individual for prophylactic use against ageing or other pathophysiological processes. However, for healthy individuals, it remains unclear what effects metformin treatment will induce on their bodies. A systematic profiling of the molecular landscape of metformin treatment is expected to provide crucial implications for this issue. Here, we delineated the first transcriptomic landscape induced by metformin in 10 tissues (aorta, brown adipose, brain, eye, heart, liver, kidney, skeletal muscle, stomach and testis) of healthy mice by using RNA-sequencing technique. A comprehensive computational analysis was performed. The overrepresentation of cardiovascular disease-related gene sets, positive correlation with hypertension-related transcriptomic signatures and the associations of drugs with hypertensive side effect together indicate that although metformin does exert various beneficial effects, it would also increase the risk of hypertension in healthy mice. This prediction was experimentally validated by an independent animal experiments. Together, this study provided important resource necessary for investigating metformin's beneficial/deleterious effects on various healthy tissues, when it is potentially prescribed to healthy individual for prophylactic use.


Asunto(s)
Perfilación de la Expresión Génica , Regulación de la Expresión Génica/efectos de los fármacos , Hipoglucemiantes/farmacología , Metformina/farmacología , Transcriptoma , Animales , Presión Sanguínea/efectos de los fármacos , Presión Sanguínea/genética , Biología Computacional/métodos , Modelos Animales de Enfermedad , Relación Dosis-Respuesta a Droga , Femenino , Hipertensión/etiología , Hipoglucemiantes/efectos adversos , Masculino , Metformina/efectos adversos , Ratones , Anotación de Secuencia Molecular , Especificidad de Órganos/efectos de los fármacos , Especificidad de Órganos/genética , Factores de Tiempo
16.
Glob Chang Biol ; 26(2): 669-681, 2020 02.
Artículo en Inglés | MEDLINE | ID: mdl-31344298

RESUMEN

Species-rich plant communities have been shown to be more productive and to exhibit increased long-term soil organic carbon (SOC) storage. Soil microorganisms are central to the conversion of plant organic matter into SOC, yet the relationship between plant diversity, soil microbial growth, turnover as well as carbon use efficiency (CUE) and SOC accumulation is unknown. As heterotrophic soil microbes are primarily carbon limited, it is important to understand how they respond to increased plant-derived carbon inputs at higher plant species richness (PSR). We used the long-term grassland biodiversity experiment in Jena, Germany, to examine how microbial physiology responds to changes in plant diversity and how this affects SOC content. The Jena Experiment considers different numbers of species (1-60), functional groups (1-4) as well as functional identity (small herbs, tall herbs, grasses, and legumes). We found that PSR accelerated microbial growth and turnover and increased microbial biomass and necromass. PSR also accelerated microbial respiration, but this effect was less strong than for microbial growth. In contrast, PSR did not affect microbial CUE or biomass-specific respiration. Structural equation models revealed that PSR had direct positive effects on root biomass, and thereby on microbial growth and microbial biomass carbon. Finally, PSR increased SOC content via its positive influence on microbial biomass carbon. We suggest that PSR favors faster rates of microbial growth and turnover, likely due to greater plant productivity, resulting in higher amounts of microbial biomass and necromass that translate into the observed increase in SOC. We thus identify the microbial mechanism linking species-rich plant communities to a carbon cycle process of importance to Earth's climate system.


Asunto(s)
Carbono , Suelo , Biomasa , Alemania , Microbiología del Suelo
17.
Soil Biol Biochem ; 135: 304-315, 2019 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-31579295

RESUMEN

Microbial nitrogen use efficiency (NUE) is the efficiency by which microbes allocate organic N acquired to biomass formation relative to the N in excess of microbial demand released through N mineralization. Microbial NUE thus is critical to estimate the capacity of soil microbes to retain N in soils and thereby affects inorganic N availability to plants and ecosystem N losses. However, how soil temperature and soil moisture/O2 affect microbial NUE to date is not clear. Therefore, two independent incubation experiments were conducted with soils from three land uses (cropland, grassland and forest) on two bedrocks (silicate and limestone). Soils were exposed to 5, 15 and 25 °C overnight at 60% water holding capacity (WHC) or acclimated to 30 and 60% WHC at 21% O2 and to 90% WHC at 1% O2 over one week at 20 °C. Microbial NUE was measured as microbial growth over microbial organic N uptake (the sum of growth N demand and gross N mineralization). Microbial NUE responded positively to temperature increases with Q10 values ranging from 1.30 ± 0.11 to 2.48 ± 0.67. This was due to exponentially increasing microbial growth rates with incubation temperature while gross N mineralization rates were relatively insensitive to temperature increases (Q10 values 0.66 ± 0.30 to 1.63 ± 0.15). Under oxic conditions (21% O2), microbial NUE as well as gross N mineralization were not stimulated by the increase in soil moisture from 30 to 60% WHC. Under suboxic conditions (90% WHC and 1% O2), microbial NUE markedly declined as microbial growth rates were strongly negatively affected due to increasing microbial energy limitation. In contrast, gross N mineralization rates increased strongly as organic N uptake became in excess of microbial growth N demand. Therefore, in the moisture/O2 experiment microbial NUE was mainly regulated by the shift in O2 status (to suboxic conditions) and less affected by increasing water availability per se. These temperature and moisture/O2 effects on microbial organic N metabolism were consistent across the soils differing in bedrock and land use. Overall it has been demonstrated that microbial NUE was controlled by microbial growth, and that NUE controlled gross N mineralization as an overflow metabolism when energy (C) became limiting or N in excess in soils. This study thereby greatly contributes to the understanding of short-term environmental responses of microbial community N metabolism and the regulation of microbial organic-inorganic N transformations in soils.

18.
Soil Biol Biochem ; 133: 37-49, 2019 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-31579313

RESUMEN

Proteins constitute the single largest soil organic nitrogen (SON) reservoir and its decomposition drives terrestrial N availability. Protein cleavage by extracellular enzymes is the rate limiting step in the soil organic N cycle and can be controlled by extracellular enzyme production or protein availability/stabilization in soil. Both controls can be affected by geology and land use, as well as be vulnerable to changes in soil temperature and moisture/O2. To explore major controls of soil gross protein depolymerization we sampled six soils from two soil parent materials (calcareous and silicate), where each soil type included three land uses (cropland, pasture and forest). Soil samples were subjected to three temperature treatments (5, 15, 25 °C at 60% water-holding capacity (WHC) and aerobic conditions) or three soil moisture/O2 treatments (30 and 60% WHC at 21% O2, 90% WHC at 1% O2, at 20 °C) in short-term experiments. Samples were incubated for one day in the temperature experiment and for one week in the moisture/O2 experiment. Gross protein depolymerization rates were measured by a novel 15N isotope pool dilution approach. The low temperature sensitivity of gross protein depolymerization, the lack of relationship with protease activity and strong effects of soil texture and pH demonstrate that this process is constrained by organo-mineral associations and not by soil enzyme content. This also became apparent from the inverse effects in calcareous and silicate soils caused by water saturation/O2 limitation. We highlight that the specific soil mineralogy influenced the response of gross depolymerization rates to water saturation/O2 limitation, causing (I) increasing gross depolymerization rates due to release of adsorbed proteins by reductive dissolution of Fe- and Mn-oxyhydroxides in calcareous soils and (II) decreasing gross depolymerization rates due to mobilization of coagulating and toxic Al3+ compounds in silicate soils.

19.
Soil Biol Biochem ; 128: 45-55, 2019 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-31579288

RESUMEN

The ratio of carbon (C) that is invested into microbial growth to organic C taken up is known as microbial carbon use efficiency (CUE), which is influenced by environmental factors such as soil temperature and soil moisture. How microbes will physiologically react to short-term environmental changes is not well understood, primarily due to methodological restrictions. Here we report on two independent laboratory experiments to explore short-term temperature and soil moisture effects on soil microbial physiology (i.e. respiration, growth, CUE, and microbial biomass turnover): (i) a temperature experiment with 1-day pre-incubation at 5, 15 and 25 °C at 60% water holding capacity (WHC), and (ii) a soil moisture/oxygen (O2) experiment with 7-day pre-incubation at 20 °C at 30%, 60% WHC (both at 21% O2) and 90% WHC at 1% O2. Experiments were conducted with soils from arable, pasture and forest sites derived from both silicate and limestone bedrocks. We found that microbial CUE responded heterogeneously though overall positively to short-term temperature changes, and decreased significantly under high moisture level (90% WHC)/suboxic conditions due to strong decreases in microbial growth. Microbial biomass turnover time decreased dramatically with increasing temperature, and increased significantly at high moisture level (90% WHC)/suboxic conditions. Our findings reveal that the responses of microbial CUE and microbial biomass turnover to short-term temperature and moisture/O2 changes depended mainly on microbial growth responses and less on respiration responses to the environmental cues, which were consistent across soils differing in land use and geology.

20.
Soil Biol Biochem ; 136: 107521, 2019 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-31700196

RESUMEN

Microorganisms are critical in mediating carbon (C) and nitrogen (N) cycling processes in soils. Yet, it has long been debated whether the processes underlying biogeochemical cycles are affected by the composition and diversity of the soil microbial community or not. The composition and diversity of soil microbial communities can be influenced by various environmental factors, which in turn are known to impact biogeochemical processes. The objectives of this study were to test effects of multiple edaphic drivers individually and represented as the multivariate soil environment interacting with microbial community composition and diversity, and concomitantly on multiple soil functions (i.e. soil enzyme activities, soil C and N processes). We employed high-throughput sequencing (Illumina MiSeq) to analyze bacterial/archaeal and fungal community composition by targeting the 16S rRNA gene and the ITS1 region of soils collected from three land uses (cropland, grassland and forest) deriving from two bedrock forms (silicate and limestone). Based on this data set we explored single and combined effects of edaphic variables on soil microbial community structure and diversity, as well as on soil enzyme activities and several soil C and N processes. We found that both bacterial/archaeal and fungal communities were shaped by the same edaphic factors, with most single edaphic variables and the combined soil environment representation exerting stronger effects on bacterial/archaeal communities than on fungal communities, as demonstrated by (partial) Mantel tests. We also found similar edaphic controls on the bacterial/archaeal/fungal richness and diversity. Soil C processes were only directly affected by the soil environment but not affected by microbial community composition. In contrast, soil N processes were significantly related to bacterial/archaeal community composition and bacterial/archaeal/fungal richness/diversity but not directly affected by the soil environment. This indicates direct control of the soil environment on soil C processes and indirect control of the soil environment on soil N processes by structuring the microbial communities. The study further highlights the importance of edaphic drivers and microbial communities (i.e. composition and diversity) on important soil C and N processes.

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