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Results for “CELL DIVISION”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 145 records · Page 8

Overexpression of miR-133 decrease primary endothelial cells proliferation and migration via FGFR1 targeting

Highlights: • FGFR1 signaling can bring about angiogenesis in cancer. • Through downregulating FGFR1, miR-133 caused reductions in bFGF activity. • Reduced bFGF activity result in diminished proliferation and migratory ability of ECs. • Overexpression of miR-133 could reduce the rate of cell division. • MiR-133 could disturb capillary network formation of transfected ECs as well. Angiogenesis is one of the essential hallmarks of cancer that is controlled by the balance between positive and negative regulators. FGFR1 signaling is crucial for the execution of bFGF-induced proliferation, migration, and tube formation of endothelial cells (ECs) and onset of angiogenesis on tumors. The purpose of this study is to identify whether or not miR-133 regulates FGFR1 expression and accordingly hypothesize if it plays a crucial role in modulating bFGF/FGFR1 activity in ECs and blocking tumor angiogenesis through targeting FGFR1. The influences of miR-133 overexpression on bFGF stimulated endothelial cells were assessed by cell growth curve, MTT assaying, tube formation, and migration assays. Forced expression of miR-133 caused significant reductions in bFGF-induced proliferation and migratory ability of ECs. MiR-133 Expression was negatively correlated with both mRNA and protein levels of FGFR1 in the transfected ECs isolated from peripheral blood. Moreover, overexpression of miR-133 drastically reduced the rate of cell division and disturbed capillary network formation of transfected ECs. These findings suggest that miR-133 plays an important function in bFGF-induced angiogenesis processes in ECs and provides a rationale for new therapeutic approaches to suppress tumor angiogenesis and cancer.

60 APPLIED LIFE SCIENCES↗

Non-Ionizing Millimeter Waves Non-Thermal Radiation of Saccharomyces cerevisiae—Insights and Interactions

Non-ionizing millimeter-waves (MMW) interact with cells in a variety of ways. Here the inhibited cell division effect was investigated using 85–105 GHz MMW irradiation within the International Commission on Non-Ionizing Radiation Protection (ICNIRP) non-thermal 20 mW/cm 2 safety standards. Irradiation using a power density of about 1.0 mW/cm 2 SAR over 5–6 h on 50 cells/μL samples of Saccharomyces cerevisiae model organism resulted in 62% growth rate reduction compared to the control (sham). The effect was specific for 85–105 GHz range and was energy- and cell density-dependent. Irradiation of wild type and Δrad52 (DNA damage repair gene) deleted cells presented no differences of colony growth profiles indicating non-thermal MMW treatment does not cause permanent genetic alterations. Dose versus response relations studied using a standard horn antenna (~1.0 mW/cm 2 ) and compared to that of a compact waveguide (17.17 mW/cm 2 ) for increased power delivery resulted in complete termination of cell division via non-thermal processes supported by temperature rise measurements. We have shown that non-thermal MMW radiation has potential for future use in treatment of yeast related diseases and other targeted biomedical outcomes.

59 BASIC BIOLOGICAL SCIENCES↗

SU-E-J-102: Separation of Metabolic Supply and Demand: From Power Grid Economics to Cancer Metabolism

Purpose: To study a new model of glucose metabolism which is primarily governed by the timescale of the energetic demand and not by the oxygen level, and its implication on cancer metabolism (Warburg effect) Methods: 1) Metabolic profiling of membrane transporters activity in several cell lines, which represent the spectrum from normal breast epithelium to aggressive, metastatic cancer, using Seahorse XF reader.2) Spatial localization of oxidative and non-oxidative metabolic components using immunocytochemical imaging of the glycolytic ATP-producing enzyme, pyruvate kinase and mitochondria. 3) Finite element simulations of coupled partial differential equations using COMSOL and MATLAB. Results: Inhibition or activation of pumps on the cell membrane led to reduction or increase in aerobic glycolysis, respectively, while oxidative phosphorylation remained unchanged. These results were consistent with computational simulations of changes in short-timescale demand for energy by cell membrane processes. A specific model prediction was that the spatial distribution of ATP-producing enzymes in the glycolytic pathway must be primarily localized adjacent to the cell membrane, while mitochondria should be predominantly peri-nuclear. These predictions were confirmed experimentally. Conclusion: The results in this work support a new model for glucose metabolism in which glycolysis and oxidative phosphorylation supply different types of energy demand. Similar to power grid economics, optimal metabolic control requires the two pathways, even in normoxic conditions, to match two different types of energy demands. Cells use aerobic metabolism to meet baseline, steady energy demand and glycolytic metabolism to meet short-timescale energy demands, mainly from membrane transport activities, even in the presence of oxygen. This model provides a mechanism for the origin of the Warburg effect in cancer cells. Here, the Warburg effect emerges during carcinogenesis is a physiological response to an increase in energy demands from membrane transporters, required for cell division, growth, and migration. This work is supported by the NIH Physical Sciences in Oncology Center grant 1U54CA143970-03 and NIH R01 CA077575-10.

60 APPLIED LIFE SCIENCES↗

Time as a microbial resource

Microbes need resources for energy and cellular building material. They also need access to clement conditions with liquid water and a cellular damage rate that is lower than repair. When deprived of resources and clement conditions, microbes often enter some form of dormancy (e.g., by ceasing cell division, slowing metabolic rate, or forming an endospore) until they can grow again. For example, at night, phototrophs wait for the sun to return. In winter, soil microbes wait for warmer temperatures. Microbes that cause diseases like tuberculosis can stay dormant for years, waiting for the cessation of antibiotic or immune system bombardment. But what about longer timescales? Unlike multicellular life, microbes survive in an extremely broad range of conditions and can access an amazing variety of resources to maintain cellular functions in the absence of cell division. This means that they have the potential to be dormant for much longer than a few months or years. There is no theoretical reason microbes cannot survive on maintenance energy for hundreds or thousands of years, or longer, with little to no cell proliferation. Here, given this lack of theoretical constraints on the length of microbial dormancy intervals, two questions arise, (i) is there evidence for the existence of organisms experiencing very long dormancies? And (ii) what could be the advantages of such long wait times?

54 ENVIRONMENTAL SCIENCES↗

Use of abnormal preprophase bands to decipher division plane determination

Many premitotic plant cells possess a cortical preprophase band of microtubules and actin filaments that encircles the nucleus. In vacuolated cells, the preprophase band is visibly connected to the nucleus by a cytoplasmic raft of actin filaments and microtubules termed the phragmosome. Typically, the location of the preprophase band and phragmosome corresponds to, and thus is thought to influence, the location of the cell division plane. To better understand the function of the preprophase band and phragmosome in orienting division, we used a green fluorescent protein-based microtubule reporter protein to observe mitosis in living tobacco bright yellow 2 cells possessing unusual preprophase bands. Observations of mitosis in these unusual cells support the involvement of the preprophase band/phragmosome in properly positioning the preprophase nucleus, influencing spindle orientation such that the cytokinetic phragmoplast initially grows in an appropriate direction, and delineating a region in the cell cortex that attracts microtubules and directs later stages of phragmoplast growth. Thus, the preprophase band/phragmosome appears to perform several interrelated functions to orient the division plane. However, functional information associated with the preprophase band is not always used or needed and there appears to be an age or distance-dependent character to the information. Cells treated with the anti-actin drug, latrunculin B, are still able to position the preprophase nucleus suggesting that microtubules may play a dominant role in premitotic positioning. Furthermore, in treated cells, spindle location and phragmoplast insertion are frequently abnormal suggesting that actin plays a significant role in nuclear anchoring and phragmoplast guidance. Thus, the microtubule and actin components of the preprophase band/phragmosome execute complementary activities to ensure proper orientation of the division plane.

NASA Discipline Plant Biology↗

Disruption of estrogen homeostasis as a mechanism for uterine toxicity in Wistar Han rats treated with tetrabromobisphenol A

Chronic oral treatment of tetrabromobisphenol A (TBBPA) to female Wistar Han rats resulted in increased incidence of cell proliferation at 250 mg/kg and tumor formation in the uterus at higher doses. The present study was designed to test the hypothesis that disruption of estrogen homeostasis was a major mode-of-action for the observed effects. Biological changes were assessed in serum, liver, and the proximal (nearest the cervix) and distal (nearest the ovaries) sections of the uterine horn of Wistar Han rats 24 h following administration of the last of five daily oral doses of 250 mg/kg. Expression of genes associated with receptors, biosynthesis, and metabolism of estrogen was altered in the liver and uterus. TBBPA treatment also resulted in changes in expression of genes associated with cell division and growth. Changes were also observed in the concentration of thyroxine in serum and in expression of genes in the liver and uterus associated with thyroid hormone receptors. Differential expression of some genes was tissue-dependent or specific to tissue location in the uterus. The biological responses observed in the present study support the hypothesis that perturbation of estrogen homeostasis is a major mode-of-action for TBBPA-mediated cell proliferation and tumorigenesis previously observed in the uterus of TBBPA-treated Wistar Han rats. - Highlights: • Perturbation of estrogen homeostasis in TBBPA-treated female rats was investigated. • Gene expression changes were observed in the liver and uterus of these rats. • Genes associated with estrogen biosynthesis and metabolism were affected. • Genes associated with thyroid homeostasis and cell division/growth were affected. • A mechanism of uterine toxicity via endocrine disruption was indicated.

60 APPLIED LIFE SCIENCES↗

Functional analysis of the Hikeshi-like protein and its interaction with HSP70 in Arabidopsis

Highlights: • HKL, a Hikeshi homologous gene is identified in Arabidopsis. • HKL interacts with two HSP70 isoforms and regulates the subcellular localization of HSC70-1. • The two HSP70 translocate into nucleus in response to heat stress. • Overexpression of HKL confers thermotolerance in transgenic plants. - Abstract: Heat shock proteins (HSPs) refold damaged proteins and are an essential component of the heat shock response. Previously, the 70 kDa heat shock protein (HSP70) has been reported to translocate into the nucleus in a heat-dependent manner in many organisms. In humans, the heat-induced translocation of HSP70 requires the nuclear carrier protein Hikeshi. In the Arabidopsis genome, only one gene encodes a protein with high homology to Hikeshi, and we named this homolog Hikeshi-like (HKL) protein. In this study, we show that two Arabidopsis HSP70 isoforms accumulate in the nucleus in response to heat shock and that HKL interacts with these HSP70s. Our histochemical analysis revealed that HKL is predominantly expressed in meristematic tissues, suggesting the potential importance of HKL during cell division in Arabidopsis. In addition, we show that HKL regulates HSP70 localization, and HKL overexpression conferred thermotolerance to transgenic Arabidopsis plants. Our results suggest that HKL plays a positive role in the thermotolerance of Arabidopsis plants and cooperatively interacts with HSP70.

60 APPLIED LIFE SCIENCES↗

Reparative neurogenesis after cerebral ischemia: Clinical application prospects

At the present time two main approaches are in the focus of neurobiological studies of brain recovery after a stroke. One of them is concerned with the infusion of stem cells in damaged brain. The second approach is directed at the stimulation of endogenous reparative processes, in particular, adult neurogenesis. This review considers alterations of adult neurogenesis caused by cerebral ischemia and possible pathways of its regulation. Multiple studies on animal models have shown that adult neurogenesis is mostly increased by cerebral ischemia. In spite of increasing proliferation and moving neural progenitors to infarct zone, most newborn neurons die before reaching maturity. Besides, an increase of neurogenesis in pathological conditions is mainly due to recruitment of new stem cells, but not due to an additional precursor-cells division that results in an overall decline of the regeneration capacity. Thus, the endogenous reparative mechanisms are not sufficient, and the search for new targets to promote proliferation, survival, and maturation of new neurons after a stroke is needed. Neurotransmitter systems and anti-inflammatory drugs are considered as potential regulators of post-ischemic neurogenesis growth factors.

60 APPLIED LIFE SCIENCES↗

Crystal structure and potential physiological role of zebra fish thioesterase superfamily member 2 (fTHEM2)

Thioesterase superfamily member 2 (THEM2) is an essential protein for mammalian cell proliferation. It belongs to the hotdog-fold thioesterase superfamily and catalyzes hydrolysis of thioester bonds of acyl-CoA in vitro, while its in vivo function remains unrevealed. In this study, Zebra fish was selected as a model organism to facilitate the investigations on THEM2. First, we solved the crystal structure of recombinant fTHEM2 at the resolution of 1.80 Å, which displayed a similar scaffolding as hTHEM2. Second, functional studies demonstrated that fTHEM2 is capable of hydrolyzing palmitoyl-CoA in vitro. In addition, injection of morpholino against fTHEM2 at one-cell stage resulted in distorted early embryo development, including delayed cell division, retarded development and increased death rate. The above findings validated our hypothesis that fTHEM2 could serve as an ideal surrogate for studying the physiological functions of THEM2. - Highlights: • The crystal structure of recombinant fTHEM2 is presented. • fTHEM2 is capable of hydrolyzing palmitoyl-CoA. • The influence of fTHEM2 on early embryo development is demonstrated.

60 APPLIED LIFE SCIENCES↗

Mechanically induced localisation of SECONDARY WALL INTERACTING bZIP is associated with thigmomorphogenic and secondary cell wall gene expression

Plant growth requires the integration of internal and external cues, perceived and transduced into a developmental programme of cell division, elongation and wall thickening. Mechanical forces contribute to this regulation, and thigmomorphogenesis typically includes reducing stem height, increasing stem diameter, and a canonical transcriptomic response. We present data on a bZIP transcription factor involved in this process in grasses. Brachypodium distachyon SECONDARY WALL INTERACTING bZIP (SWIZ) protein translocated into the nucleus following mechanostimulation. Classical touch-responsive genes were upregulated in B. distachyon roots following touch, including significant induction of the glycoside hydrolase 17 family, which may be unique to grass thigmomorphogenesis. SWIZ protein binding to an E-box variant in exons and introns was associated with immediate activation followed by repression of gene expression. SWIZ overexpression resulted in plants with reduced stem and root elongation. These data further define plant touch-responsive transcriptomics and physiology, offering insights into grass mechanotranduction dynamics.

Coomey, Joshua↗

A p53-inducible microRNA-34a downregulates Ras signaling by targeting IMPDH

Highlights: Black-Right-Pointing-Pointer p53 downregulates IMPDH. Black-Right-Pointing-Pointer p53-dependent miR-34a transactivation inhibits IMPDH transcription. Black-Right-Pointing-Pointer miR-34a-mediated inhibition of IMPDH downregulates GTP-dependent Ras signal. -- Abstract: p53 is a well-known transcription factor that controls cell cycle arrest and cell death in response to a wide range of stresses. Moreover, p53 regulates glucose metabolism and its mutation results in the metabolic switch to the Warburg effect found in cancer cells. Nucleotide biosynthesis is also critical for cell proliferation and the cell division cycle. Nonetheless, little is known about whether p53 regulates nucleotide biosynthesis. Here we demonstrated that p53-inducible microRNA-34a (miR-34a) repressed inosine 5 Prime -monophosphate dehydrogenase (IMPDH), a rate-limiting enzyme of de novo GTP biosynthesis. Treatment with anti-miR-34a inhibitor relieved the expression of IMPDH upon DNA damage. Ultimately, miR-34a-mediated inhibition of IMPDH resulted in repressed activation of the GTP-dependent Ras signaling pathway. In summary, we suggest that p53 has a novel function in regulating purine biosynthesis, aided by miR-34a-dependent IMPDH repression.

60 APPLIED LIFE SCIENCES↗

Sealable femtoliter chamber arrays for cell-free biology

Cell-free systems provide a flexible platform for probing specific networks of biological reactions isolated from the complex resource sharing (e.g. global gene expression, cell division) encountered within living cells. However, such systems, used in conventional macro-scale bulk reactors, often fail to exhibit the dynamic behaviors and efficiencies characteristic of their living micro-scale counterparts. Understanding the impact of internal cell structure and scale on reaction dynamics is crucial to understanding complex gene networks. Here we report a microfabricated device that confines cell-free reactions in cellular scale volumes while allowing flexible characterization of the enclosed molecular system. This multilayered poly(dimethylsiloxane) (PDMS) device contains femtoliter-scale reaction chambers on an elastomeric membrane which can be actuated (open and closed). When actuated, the chambers confine Cell-Free Protein Synthesis (CFPS) reactions expressing a fluorescent protein, allowing for the visualization of the reaction kinetics over time using time-lapse fluorescent microscopy. Lastly, we demonstrate how this device may be used to measure the noise structure of CFPS reactions in a manner that is directly analogous to those used to characterize cellular systems, thereby enabling the use of noise biology techniques to characterize CFPS gene circuits and their interactions with the cell-free environment.

59 BASIC BIOLOGICAL SCIENCES↗

The cross roles of sphingosine kinase 1/2 and ceramide glucosyltransferase in cell growth and death

Sphingosine-1-phosphate is synthesized by two sphingosine kinases, cytosolic SK1 and nuclear SK2 but SK2 expression was much higher than SK1in mouse skin fibroblasts. However, in SK2{sup −/−} cells, SK1 expression was markedly increased to SK2 levels whereas in SK1{sup −/−} cells, SK2 expression was unaffected. Ceramide, glucosylceramide and sphingosine levels were all increased in SK1{sup −/−} but less so in SK2{sup −/−} cells and S1P levels were not significantly reduced in either SK1{sup −/−} or SK2{sup −/−} cells. Greatly increased Ceramide glucosyltransferase expression was observed in SK1{sup −/−} cells but less so in SK2{sup −/−} cells suggested a role in drug resistance. SK2{sup −/−} cells grew faster than control and SK1{sup −/−}. The cell division gene PCNA was significantly overexpressed in SK2{sup −/−} cells, suggesting a cross regulation between SKs and Ceramide glucosyltransferase.

60 APPLIED LIFE SCIENCES↗

Regulation of assimilate import into sink organs: update on molecular drivers of sink strength

Recent developments have altered our view of molecular mechanisms that determine sink strength, defined here as the capacity of non-photosynthetic structures to compete for import of photoassimilates. We review new findings from diverse systems, including stems, seeds, flowers, and fruits. An important advance has been the identification of new transporters and facilitators with major roles in the accumulation and equilibration of sugars at a cellular level. Exactly where each exerts its effect varies among systems. Sugarcane and sweet sorghum stems, for example, both accumulate high levels of sucrose, but may do so via different paths. The distinction is central to strategies for targeted manipulation of sink strength using transporter genes, and shows the importance of system-specific analyses. Another major advance has been the identification of deep hypoxia as a feature of normal grain development. This means that molecular drivers of sink strength in endosperm operate in very low oxygen levels, and under metabolic conditions quite different than previously assumed. Successful enhancement of sink strength has nonetheless been achieved in grains by up-regulating genes for starch biosynthesis. Additionally, our understanding of sink strength is enhanced by awareness of the dual roles played by invertases (INVs), not only in sucrose metabolism, but also in production of the hexose sugar signals that regulate cell cycle and cell division programs. These contributions of INV to cell expansion and division prove to be vital for establishment of young sinks ranging from flowers to fruit. Since INV genes are themselves sugar-responsive “feast genes,” they can mediate a feed-forward enhancement of sink strength when assimilates are abundant. Greater overall productivity and yield have thus been attained in key instances, indicating that even broader enhancements may be achievable as we discover the detailed molecular mechanisms that drive sink strength in diverse systems.

54 ENVIRONMENTAL SCIENCES↗

Production of minimally disturbed synchronous cultures of hematopoietic cells

A method is describedforproducing sizable quantities of synchronously dividing, minimally disturbed mammalian cells. Cultures were grown immobilized on surfaces such that cell division within the population resulted in the continuous release of synchronous newborn cells. As judged by the quality and duration of synchronous growth, cell size distributions, and DNA compositions, newborn mouse L1210 cells grew with a very high level of synchrony without overt evidence of growth disturbances. The technology should be applicable to a variety of hematopoietic cells, as evidenced by similar results with human MOLT-4 and U937 cell lines.

Non-NASA Center↗

Two-stage model of radon-induced malignant lung tumors in rats: effects of cell killing

A two-stage stochastic model of carcinogenesis is used to analyze lung tumor incidence in 3750 rats exposed to varying regimens of radon carried on a constant-concentration uranium ore dust aerosol. New to this analysis is the parameterization of the model such that cell killing by the alpha particles could be included. The model contains parameters characterizing the rate of the first mutation, the net proliferation rate of initiated cells, the ratio of the rates of cell loss (cell killing plus differentiation) and cell division, and the lag time between the appearance of the first malignant cell and the tumor. Data analysis was by standard maximum likelihood estimation techniques. Results indicate that the rate of the first mutation is dependent on radon and consistent with in vitro rates measured experimentally, and that the rate of the second mutation is not dependent on radon. An initial sharp rise in the net proliferation rate of initiated cell was found with increasing exposure rate (denoted model I), which leads to an unrealistically high cell-killing coefficient. A second model (model II) was studied, in which the initial rise was attributed to promotion via a step function, implying that it is due not to radon but to the uranium ore dust. This model resulted in values for the cell-killing coefficient consistent with those found for in vitro cells. An "inverse dose-rate" effect is seen, i.e. an increase in the lifetime probability of tumor with a decrease in exposure rate. This is attributed in large part to promotion of intermediate lesions. Since model II is preferable on biological grounds (it yields a plausible cell-killing coefficient), such as uranium ore dust. This analysis presents evidence that a two-stage model describes the data adequately and generates hypotheses regarding the mechanism of radon-induced carcinogenesis.

NASA Program Radiation Health↗

3D pattern formation of a protein–membrane suspension

Many essential cellular processes, including cell division and the establishment of cell polarity during embryogenesis, are regulated by pattern-forming proteins. These proteins often need to bind to a substrate, such as the cell membrane, onto which they interact and form two-dimensional (2D) patterns. It is unclear how the membrane’s continuity and dimensionality impact pattern formation. Here, we address this gap using the MinDE system, a prototypical example of pattern-forming membrane proteins. We show that when the lipid substrate is fragmented into submicrometer-sized diffusive liposomes, adenosine triphosphate-driven protein–protein interactions generate three-dimensional (3D) spatially extended patterns, despite the complete loss of membrane continuity. Remarkably, these 3D patterns emerge at scales four orders of magnitude larger than the individual liposomes. By systematically varying protein concentration, liposome size, and density, we observed and characterized a variety of 3D dynamical patterns not seen on continuous 2D membranes, including traveling waves, dynamical spirals, and a coexistence phase. Simulations and linear stability analysis of a coarse-grained model revealed that the physical properties of the dispersed membrane effectively rescale both the protein–membrane binding rates and diffusion, two key parameters governing pattern formation and wavelength selection. These findings highlight the robustness of Min’s pattern-forming ability, suggesting that protein–membrane suspensions could serve as an adaptable template for studying out-of-equilibrium self-organization in 3D, beyond in vivo contexts.

36 MATERIALS SCIENCE↗

Study of Oak Ridge soils using BONCAT-FACS-Seq reveals that a large fraction of the soil microbiome is active

The ability to link soil microbial diversity to soil processes requires technologies that differentiate active subpopulations of microbes from so-called relic DNA and dormant cells. Measures of microbial activity based on various techniques including DNA labelling have suggested that most cells in soils are inactive, a fact that has been difficult to reconcile with observed high levels of bulk soil activities. We hypothesized that measures of in situ DNA synthesis may be missing the soil microbes that are metabolically active but not replicating, and we therefore applied BONCAT (Bioorthogonal Non Canonical Amino Acid Tagging) i.e. a proxy for activity that does not rely on cell division, to measure translationally active cells in soils. We compared the active population of two soil depths from Oak Ridge (TN) incubated under the same conditions for up to seven days. Depending on the soil, a maximum of 25 – 70% of the cells were active, accounting for 3-4 million cells per gram of soil type, which is an order of magnitude higher than previous estimates. The BONCAT positive cell fraction was recovered by fluorescence activated cell sorting (FACS) and identified by 16S rDNA amplicon sequencing. The diversity of the active fraction was a selected subset of the bulk soil community. Excitingly, some of the same members of the community were recruited at both depths independently from their abundance rank. On average, 86% of sequence reads recovered from the active community shared >97% sequence similarity with cultured isolates from the field site. Our observations are in line with a recent report that, of the few taxa that are both abundant and ubiquitous in soil, 45% are also cultured – and indeed some of these ubiquitous microorganisms were found to be translationally active. The use of BONCAT on soil microbiomes provides evidence that a large portion of the soil microbes can be active simultaneously. We conclude that BONCAT coupled to FACS and sequencing is effective for interrogating the active fraction of soil microbiomes in situ and provides new perspectives to link metabolic capacity to overall soil ecological traits and processes.

58 GEOSCIENCES↗