Search for more papers by this author. Significance: The precise role and impact of reactive oxygen species ROS in stem cells, which are essential for lifelong tissue homeostasis and regeneration, remain of significant interest to the field. The long-term regenerative potential of a stem cell compartment is determined by the delicate balance between quiescence, self-renewal, and differentiation, all of which can be influenced by ROS levels.
The role of glutamate in neuronal ion homeostasis: A case study of spreading depolarization.
Recent Advances: The past decade has seen a growing appreciation for the importance of ROS and redox homeostasis in various stem cell compartments, particularly those of hematopoietic, neural, and muscle tissues. In recent years, the importance of proteostasis and mitochondria in relation to stem cell biology and redox homeostasis has garnered considerable interest.
Critical Issues: Here, we explore the reciprocal relationship between ROS and stem cells, with significant emphasis on mitochondria as a core component of redox homeostasis. We discuss how redox signaling, involving cell-fate determining protein kinases and transcription factors, can control stem cell function and fate. We also address the impact of oxidative stress on stem cells, especially oxidative damage of lipids, proteins, and nucleic acids. We further discuss ROS management in stem cells, and present recent evidence supporting the importance of mitochondrial activity and its modulation via mitochondrial clearance, biogenesis, dynamics, and distribution [ i.
Future Directions: Therefore, elucidating the intricate links between mitochondria, cellular metabolism, and redox homeostasis is envisioned to be critical for our understanding of ROS in stem cell biology and its therapeutic relevance in regenerative medicine. Redox Signal. Login to your account Username. Forgot password? Keep me logged in. New User. Change Password. Old Password. New Password. Password Changed Successfully Your password has been changed.
Create a new account Email. Returning user. Can't sign in? The potential P flux defined here provides a good indicator for assessing P concentration gradients between overlying water and porewater, with high values suggesting a high risk of P transfer from soil to overlying water. In this study, aquatic macrophytes e.
Data collected from water and soil samples were expressed as the mean plus standard error. Paired Student's t -tests were used to compare the effects of warming on soil microorganism and C fractions, P concentrations in porewater and overlying water, and potential P flux. On average, potential P flux in the six wetlands ranged from 0. Two-way analysis of variance indicated that experimental warming significantly increased potential P flux, except in the SQ wetland.
There were also significant differences in soil C pools and potential P flux between Warmed and Control treatments Table 3. A significant interaction between treatment and season sampling date was found for soil C pools and potential P flux as well, although there were no significant differences in these variables by season alone. The values of H in the warmed treatment were lower than those in the control, with H values of 1.
Ecosystem Dynamics – Systems Innovation
Results from the other two samplings data not shown were fundamentally similar to the Mar. There was no consistent pattern in the homeostasis model fit between DOC and microorganism C among the three samplings Table 4. However, strongly significant and positive correlations between DRP in porewater and soil microorganism biomass P fit a power model for these three consecutive samplings Fig. Sampling date is March Coefficients fitting the data to the equation for stoichiometric homeostasis are given along with an estimate of H C.
Coefficients fitting the data to the equation for stoichiometric homeostasis are given along with an estimate of H P.
Hypothesis and Theory ARTICLE
The tight linkages in this study between different pools of soil labile C and soil microbial C Fig. This supports the view that stoichiometric homeostasis is an important mechanism underpinning the dynamics of C and P resource availability at the soil-microbe interphase in wetland ecosystems. Based on the principle of homeostatic regulation ability  and its prior application to a grassland ecosystem  , decreased H values for soil labile C and DRP in warmed columns indicate that experimental warming impaired the ability of soil organisms to regulate C and P biogeochemical turnover in the studied wetland ecosystems.
This loss of homoeostatic regulation ability is consistent with the observed decrease in soil TOC Table 1 and the increase in potential P flux Table 2. Comparison of the data for the decrease in soil TOC and the increase in both soil labile C and microorganism C Table 1 further indicates that losses of total organic C in warmed soils were mainly derived from non-active C pools; i.
Recalcitrant organic fractions generally represent a large proportion of the total C pool and have relatively slow turnover rates  ,  , and generation of recalcitrant organic matter is regarded as a vital process for C sequestration . Excluding P that is assimilated into microbial biomass Table 1 , warming subjects the remaining P pool to increases in enzymatic biodegradation of organic phosphorus  , P desorption  ,  , and inorganic P solubilization  , which could enhance the strength of potential P flux Table 2 as well as increase DRP in porewater.
The ecological role of wetland soil as a source for C and P, coupled with lower H values observed in the warming treatment compared to the control, suggests that H may yield valuable insight into the ecological role of soil in C and P biogeochemical turnover and its response to global warming.
Oxygen Homeostasis and Its Dynamics
Because macronutrients are coupled with various biochemical and cellular constituents, the ratios of these elements remained relatively constant compared to the potentially decoupled resource stoichiometry changes in the surrounding environment that were induced by warming  , . This may be explained by soil microorganisms regulating the equilibrium between the elemental composition of their biomass and the efficiencies of microbial nutrient assimilation and growth through ecoenzymatic interactions .
Further, simultaneous N and P enrichment by photosynthetic biota produces strongly positive, synergistic responses in ecosystems . This is also in line with general ecological theory on the elemental stoichiometries of microbial biomass and environmental availability relative to microbial nutrient assimilation and growth  , .
For example, increases in N concentration in biomass are usually accompanied by increases in P uptake for vascular plants . In ecoenzymatic stoichiometry theory  ,  , the relative availability of hydrolyzed P via ecoenzymes such as phosphatase in soils relative to C in the microbial community composition was higher under experimental warming than in the control treatments. Furthermore, relatively high abundances of fungi in soil ecosystems increase the secretion of P-hydrolyzing enzymes in soils  ,  , .
Meanwhile, functional gene array data verified that soil P utilization genes such as polyphosphate kinase and exopolyphosphate were also enhanced by warming  , leading to increases in soil microbial P pools Table 1 and speeding up nutrient cycling processes. S3 were found for sediment sampled from the warmed column compared to the control treatment.
This indicates that the redox-enhanced sediment under the warmed treatment could increase dissimilatory reduction of P-bound metal oxides and the decomposition of organic matter, liberating P from sediment aggregates. This may explain the relatively high levels of P in porewater and potential P flux under warming Table 2. In addition to stimulating net primary production, warming could significantly increase both soil respiration and the associated C-degrading microbial genes  ,  , increasing the C flux from terrestrial ecosystems to the atmosphere in the global C cycle .
Soil C losses in this study were traced to the recalcitrant fraction, while pools of labile C were not depleted Table 1. Carbon availability from HLOC for the soil microorganism assemblage and metabolism is generally higher than for the rest of the C sources  ; therefore the index of HLOC is relatively sensitive to C dynamics for microorganism acquisition.
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Efforts to predict P flux or P dynamics from the soil biosphere to aquatic ecosystems are becoming increasingly important in light of concerns related to eutrophication, climate change, and other anthropogenic impacts  ,  ,  , . Statistics-based modeling integrates various parameters, such as soil physicochemical properties, regional meteorology, and anthropogenic activities  ,  ,  , and can be used to predict P flux under IPCC climate scenarios .
However, these models are insufficiently related to the ecological forcing of microorganisms in the soil micro-ecosystem, even though such microorganisms essentially mediate and drive Earth's biogeochemical cycles  , . Similarly, changes in potential P flux Eq 5 were jointly determined by differences in the concentration of DRP in soil porewater vs.
Moreover, values of these two indices were distinctly influenced by experimental warming Table 2 , Fig. Therefore, the strong, negative allometric relationship observed between these indices Fig.
Further, they can also both be viewed in terms of an energy landscape i. Although soil respiration at the global scale responds positively to air temperature, in the long term warming may also mobilize older stored carbon, potentially resulting in higher carbon inputs to the soil biosphere .
Such an outcome would be somewhat inconsistent with the near-term decrease in soil C stock Table 1 and increase in potential P flux Table 2 we observed in the current microcosm warming experiment. In summary, microcosm warming impaired the stoichiometric homeostatic ability H of soil microorganisms to regulate P and C biogeochemical processes. Based on our results, we advocate further use of homeostatic regulation indices H as novel ecological tools for assessing potential P flux and other biogeochemical dynamics in the face of global climate change.
Dynamics of dissolved oxygen DO concentration in overlying water during 12 d of sediment incubation.