Shifts In Nutrient Availability Research Articles

Nutrology and molecular state of art in muscle recovery and sports performance: a systematic review

Introduction: Nutrition makes it possible to recover from the negative impact of an injury induced by physical exercise. Recent progress has been made regarding gut microbiota, regenerative nutrition, and skeletal muscle metabolism. MicroRNAs (miRs) have emerged as critical regulators of numerous biological processes, modulating gene expression at the post-transcriptional level. Objective: It was to carry out a systematic review to elucidate the main considerations of nutrology and molecular state of art through exosomes, microRNAs, and nutrients in muscle recovery and sports performance. Methods: The systematic review rules of the PRISMA Platform were followed. The research was carried out from April to June 2023 in Scopus, PubMed, Science Direct, Scielo, and Google Scholar databases. The quality of the studies was based on the GRADE instrument and the risk of bias was analyzed according to the Cochrane instrument. Results and Conclusion: A total of 237 articles were found. A total of 107 articles were evaluated in full and 52 were included and developed in this systematic review study. Considering the Cochrane tool for risk of bias, the overall assessment resulted in 47 studies with a high risk of bias and 70 studies that did not meet GRADE. Based on the findings, it was concluded that dietary manipulations and metabolites may affect tissue stem cell fate decisions. Self-renewal and differentiation of mesenchymal stem cells can be regulated by manipulating vitamin C, A, or D levels and valine restriction. miRs play an important role as regulatory molecules during the muscle healing process. Myoblasts are known to secrete exosomes enriched with miRs into the inflammatory environment, whereby miR-224 is transferred to macrophages to inhibit M2 polarization. Additional data demonstrate that WNT-9a may be a direct target of miR224 for macrophage polarization. The results showed that miR-122 and myogenic markers were down-regulated in C2C12 cells after TGF-β stimulation, and overexpression of miR-122 can restore myogenesis inhibited by TGF-β. Evidence suggests that the exosome derived from mesenchymal stem cells exhibits functions similar to mesenchymal stem cells with low immunogenicity and without tumorization. High rates of intestinal self-renewal are enabled by intestinal stem cells (LGR5+) at the base of intestinal crypts. LGR5+ activity, including proliferation and differentiation rates, is affected by large shifts in nutrient availability, as occurs on a high-fat diet or fasting. The practice of physical activity, endogenous metabolites, and dietary nutrients can directly influence epigenetic enzymes.

Microbial nutrient limitation along a 2-million-year dune chronosequence

Long-term ecosystem development is characterized by a switch from nitrogen (N) to phosphorus (P) limitation of plant communities as soils age, which leads to changes in plant biomass, diversity, and foliar nutrient concentrations. Similar effects occur belowground, although the extent to which nutrient availability is the primary driver of long-term changes in soil microbial communities remains uncertain. To investigate this, we assessed proxies for soil microbial nutrient limitation along the Jurien Bay dune chronosequence in Western Australia, where a long-term decline in P availability is reflected in strong variation in plant and microbial community composition over 2 million years of soil development. We quantified carbon (C), N, and P in the soil microbial biomass, assayed soil enzymes involved in the acquisition of those nutrients from soil organic matter, and used microbial stoichiometric ratios and vector analysis of enzyme activities to assess whether long-term changes in soil nutrient availability are reflected in nutrient demand by soil microbes. Concentrations of microbial nutrients peaked in Holocene soils (1–6.5 ky), although differences in microbial P were not significant. There were no significant differences in microbial nutrient ratios (C:N, C:P, and N:P) along the chronosequence. Acid phosphatase activity increased continually throughout the chronosequence, while the activities of leucine aminopeptidase and β-glucosidase were greatest in Holocene soils and declined with increasing soil age. Corresponding vector lengths indicated greater investment in C-degrading enzymes in Holocene soils (≤6.5 ky), while vector angles indicated greater investment in the acquisition of P compared with N in Pleistocene soils (≥120 ky). Overall, these findings show that changes in nutrient availability during long-term pedogenesis at Jurien Bay are reflected in microbial investment in nutrient acquisition, but that the soil microbial biomass exhibits a remarkable degree of homeostasis despite major shifts in nutrient availability and community composition over 2 million years of ecosystem development.

The Important Role of Protein Kinases in the p53 Sestrin Signaling Pathway.

p53, a crucial tumor suppressor and transcription factor, plays a central role in the maintenance of genomic stability and the orchestration of cellular responses such as apoptosis, cell cycle arrest, and DNA repair in the face of various stresses. Sestrins, a group of evolutionarily conserved proteins, serve as pivotal mediators connecting p53 to kinase-regulated anti-stress responses, with Sestrin 2 being the most extensively studied member of this protein family. These responses involve the downregulation of cell proliferation, adaptation to shifts in nutrient availability, enhancement of antioxidant defenses, promotion of autophagy/mitophagy, and the clearing of misfolded proteins. Inhibition of the mTORC1 complex by Sestrins reduces cellular proliferation, while Sestrin-dependent activation of AMP-activated kinase (AMPK) and mTORC2 supports metabolic adaptation. Furthermore, Sestrin-induced AMPK and Unc-51-like protein kinase 1 (ULK1) activation regulates autophagy/mitophagy, facilitating the removal of damaged organelles. Moreover, AMPK and ULK1 are involved in adaptation to changing metabolic conditions. ULK1 stabilizes nuclear factor erythroid 2-related factor 2 (Nrf2), thereby activating antioxidative defenses. An understanding of the intricate network involving p53, Sestrins, and kinases holds significant potential for targeted therapeutic interventions, particularly in pathologies like cancer, where the regulatory pathways governed by p53 are often disrupted.

Paleoenvironmental changes across the Mesozoic–Paleogene hyperthermal events

Extreme climate warmth (hyperthermal) events through deep-time offer prescient insights into how the Earth may respond to present-day warming related to greenhouse gas emissions. This special issue deals with Paleoenvironmental changes across the Mesozoic–Paleogene hyperthermal events and comprises 25 interdisciplinary research articles. In this review paper, we summarise the contents of the special issue, placing it into a wider context, and demonstrate that Mesozoic–Paleogene hyperthermal events were among the most devastating and extreme climate modes in the geological record. Key findings are as follows: (1) Multi-proxy geochemical and sedimentological analyses reveal that widespread deoxygenation of oceans and megalakes was a common accompanying feature of most hyperthermals. (2) Evidence exists for complex linkages between volcanism, warm climate conditions, contemporary carbon cycles, aquatic biogeochemical cycles, wildfire activities, and climate-modulated hydrological and terrestrial weathering changes operating at seasonal, orbital and/or tectonic timescales. (3) Pronounced and rapid biological turnovers in the ocean during hyperthermals may have been linked to seawater acidification and shifts in nutrient availability, while promoting significant alterations in primary productivity, biological pump and ecosystem structures. Despite these advances, future interdisciplinary studies are needed to deliver a more comprehensive understanding of the nature and mechanism of complex environmental interactions within the Earth system, as well as the internal and external drivers that may have triggered hyperthermal events.

Effects of Experimental Warming and Canada Goldenrod Invasion on the Diversity and Function of the Soil Nematode Community

Both global warming and alien plant invasion can affect the biotic communities in the soil. Most studies are focused on the soil microbial community, but little is known about how global warming, along with alien plant invasion, affects the diversity and function of the soil nematode community. In this study, the individual and interactive effects of experimental warming and Canada goldenrod (Solidago canadensis L.) invasion on soil nematode communities were measured. Experimental air warming, in combination with different levels of S. canadensis invasion, were applied. The results showed that S. canadensis invasion significantly increased chao1, maturity, and structure indexes of the nematode community by 31.44%, 25.57%, and 329.3%, respectively, and decreased the basal index by 48.70% (all p < 0.05). Only the Simpson index was affected by the interaction between warming and S. canadensis invasion. Warming enhanced the S. canadensis invasion effect on the soil nematode community. The changes in nematode community were correlated with shifts in nutrient availability and resource stoichiometry, as well as microbes in the soil. These findings demonstrated that global warming and S. canadensis invasion may, directly and indirectly, alter the soil nematode community, which may considerably affect the functioning of underground food webs.

Mycorrhizal effects on decomposition and soil CO2 flux depend on changes in nitrogen availability during forest succession

Abstract Mycorrhizal fungi play a central role in plant nutrition and nutrient cycling, yet our understanding on their effects on free‐living microbes, soil carbon (C) decomposition and soil CO2 fluxes remains limited. Here we used trenches lined with mesh screens of varying sizes to isolate mycorrhizal hyphal effects on soil C dynamics in subtropical successional forests. We found that the presence of mycorrhizal hyphae suppressed soil CO2 fluxes by 17% in early‐successional forests, but enhanced CO2 losses by 20% and 32% in mid‐ and late‐successional forests respectively. The inhibitory effects of mycorrhizal fungi on soil CO2 fluxes in the young stands were associated with changes in soil nitrogen (N) mineralization and microbial activities, suggesting that competition between mycorrhizae and saprotrophs for N likely suppressed soil C decomposition. In the mid‐ and late‐successional stands, mycorrhizal enhancement of CO2 release from soil likely resulted from both hyphal respiration and mycorrhizal‐induced acceleration of organic matter decay. Synthesis. Our results highlight the sensitivity of mycorrhizal fungi‐saprotroph interactions to shifts in nutrient availability and demand, with important consequences for soil carbon dynamics particularly in ecosystems with low nutrient conditions. Incorporating such interactions into models should improve the simulations of forest biogeochemical cycles under global change.

Reindeer grazing history determines the responses of subarctic soil fungal communities to warming and fertilization

Composition and functioning of arctic soil fungal communities may alter rapidly due to the ongoing trends of warmer temperatures, shifts in nutrient availability, and shrub encroachment. In addition, the communities may also be intrinsically shaped by heavy grazing, which may locally induce an ecosystem change that couples with increased soil temperature and nutrients and where shrub encroachment is less likely to occur than in lightly grazed conditions. We tested how 4yr of experimental warming and fertilization affected organic soil fungal communities in sites with decadal history of either heavy or light reindeer grazing using high-throughput sequencing of the internal transcribed spacer2 ribosomal DNA region. Grazing history largely overrode the impacts of short-term warming and fertilization in determining the composition of fungal communities. The less diverse fungal communities under light grazing showed more pronounced responses to experimental treatments when compared with the communities under heavy grazing. Yet, ordination approaches revealed distinct treatment responses under both grazing intensities. If grazing shifts the fungal communities in Arctic ecosystems to a different and more diverse state, this shift may dictate ecosystem responses to further abiotic changes. This indicates that the intensity of grazing cannot be left out when predicting future changes in fungi-driven processes in the tundra.

The serine transporter SdaC prevents cell lysis upon glucose depletion in Escherichia coli.

The amino acid serine plays diverse metabolic roles, yet bacteria actively degrade exogenously provided serine via deamination to pyruvate. Serine deamination is thought to be a detoxification mechanism due to the ability of serine to inhibit several biosynthetic reactions, but this pathway remains highly active even in nutrient‐replete conditions. While investigating the physiological roles of serine deamination in different growth conditions, we discovered that Escherichia coli cells lacking the sdaCB operon, which encodes the serine transporter SdaC and the serine deaminase SdaB, lyse upon glucose depletion in a medium containing no exogenous serine but all other amino acids and nucleobases. Unexpectedly, this lysis phenotype can be recapitulated by deleting sdaC alone and can be rescued by heterologous expression of SdaC. Lysis of ΔsdaC cells can be prevented by omitting glycine from the medium, inhibiting the glycine cleavage system, or by increasing alanine availability. Together, our results reveal that the serine transporter SdaC plays a critical role in maintaining amino acid homeostasis during shifts in nutrient availability in E. coli.

Transcriptional regulation of central carbon metabolism in Pseudomonas aeruginosa

SummaryMicrobes such as Pseudomonas aeruginosa are often challenged by rapidly changing nutritional environments. In order to adapt to these shifts in nutrient availability, bacteria exert tight transcriptional control over the enzymes of central metabolism. This transcriptional control is orchestrated by a series of transcriptional repressors and activators. Although a number of these transcription factors have been identified, many others remain uncharacterized. Here, we present a simple pipeline to uncover and validate the targets of uncharacterized transcriptional regulators in P. aeruginosa. We use this approach to identify and confirm that an orthologue of the Pseudomonas fluorescens transcriptional regulator (RccR) binds to the upstream region of isocitrate lyase (aceA) in P. aeruginosa, thereby repressing flux through the glyoxylate shunt during growth on non‐C2 carbon sources.

Rapid Shifts in Soil Nutrients and Decomposition Enzyme Activity in Early Succession Following Forest Fire

While past research has studied forest succession on decadal timescales, ecosystem responses to rapid shifts in nutrient dynamics within the first months to years of succession after fire (e.g., carbon (C) burn-off, a pulse in inorganic nitrogen (N), accumulation of organic matter, etc.) have been less well documented. This work reveals how rapid shifts in nutrient availability associated with fire disturbance may drive changes in soil enzyme activity on short timescales in forest secondary succession. In this study, we evaluate soil chemistry and decomposition extracellular enzyme activity (EEA) across time to determine whether rapid shifts in nutrient availability (1–29 months after fire) might control microbial enzyme activity. We found that, with advancing succession, soil nutrients correlate with C-targeting β-1,4-glucosidase (BG) EEA four months after the fire, and with N-targeting β-1,4-N-acetylglucosaminidase (NAG) EEA at 29 months after the fire, indicating shifting nutrient limitation and decomposition dynamics. We also observed increases in BG:NAG ratios over 29 months in these recently burned soils, suggesting relative increases in microbial activity around C-cycling and C-acquisition. These successional dynamics were unique from seasonal changes we observed in unburned, forested reference soils. Our work demonstrates how EEA may shift even within the first months to years of ecosystem succession alongside common patterns of post-fire nutrient availability. Thus, this work emphasizes that nutrient dynamics in the earliest stages of forest secondary succession are important for understanding rates of C and N cycling and ecosystem development.

From Ecological Stoichiometry to Biochemical Composition: Variation in N and P Supply Alters Key Biosynthetic Rates in Marine Phytoplankton.

One of the major challenges in ecological stoichiometry is to establish how environmental changes in resource availability may affect both the biochemical composition of organisms and the species composition of communities. This is a pressing issue in many coastal waters, where anthropogenic activities have caused large changes in riverine nutrient inputs. Here we investigate variation in the biochemical composition and synthesis of amino acids, fatty acids (FA), and carbohydrates in mixed phytoplankton communities sampled from the North Sea. The communities were cultured in chemostats supplied with different concentrations of dissolved inorganic nitrogen (DIN) and phosphorus (DIP) to establish four different types of resource limitations. Diatoms dominated under N-limited, N+P limited and P-limited conditions. Cyanobacteria became dominant in one of the N-limited chemostats and green algae dominated in the one P-limited chemostat and under light-limited conditions. Changes in nutrient availability directly affected amino acid content, which was lowest under N and N+P limitation, higher under P-limitation and highest when light was the limiting factor. Storage carbohydrate content showed the opposite trend and storage FA content seemed to be co-dependent on community composition. The synthesis of essential amino acids was affected under N and N+P limitation, as the transformation from non-essential to essential amino acids decreased at DIN:DIP ≤ 6. The simple community structure and clearly identifiable nutrient limitations confirm and clarify previous field findings in the North Sea. Our results show that different phytoplankton groups are capable of adapting their key biosynthetic rates and hence their biochemical composition to different degrees when experiencing shifts in nutrient availability. This will have implications for phytoplankton growth, community structure, and the nutritional quality of phytoplankton as food for higher trophic levels.

Bumble bees selectively use native and exotic species to maintain nutritional intake across highly variable and invaded local floral resource pools

1. Changes to plant community composition after invasion are well documented but how these shifts directly affect higher trophic levels is still poorly understood. One potentially important factor is the change in nutritional availability after an invasion. Shifts in nutrient availability could affect the nutrient intake of organisms that live in invaded habitats, causing reduced fecundity and survival.2. The effects of the interaction among nutrient availability, selection, and diet on nutrient intake of a native bumble bee were examined. No nutritional differences were found between exotic and native pollen or collected and non‐collected pollen in protein or amino acid content, suggesting that differences in nutrient intake from random are based on selection.3. Nutrient intake was simulated when pollen was selected randomly across all available plant species and when selection was restricted to native plants only or exotic plants only using a permutation model and compared with observed collection. The results suggest that pollen collection is non‐random and that selecting only native or exotic plants cannot provide the protein or amino acid intake observed.4. These results may help to explain why the responses of native bees to exotic plants are so variable. If the exotic plants in a community can supply the necessary nutrients, bees may readily incorporate them into their diets, but if not, exotic plants may be avoided.

Minireview: hey U(PS): metabolic and proteolytic homeostasis linked via AMPK and the ubiquitin proteasome system.

One of the master regulators of both glucose and lipid cellular metabolism is 5'-AMP-activated protein kinase (AMPK). As a metabolic pivot that dynamically responds to shifts in nutrient availability and stress, AMPK dysregulation is implicated in the underlying molecular pathology of a variety of diseases, including cardiovascular diseases, diabetes, cancer, neurological diseases, and aging. Although the regulation of AMPK enzymatic activity by upstream kinases is an active area of research, less is known about regulation of AMPK protein stability and activity by components of the ubiquitin-proteasome system (UPS), the cellular machinery responsible for both the recognition and degradation of proteins. Furthermore, there is growing evidence that AMPK regulates overall proteasome activity and individual components of the UPS. This review serves to identify the current understanding of the interplay between AMPK and the UPS and to promote further exploration of the relationship between these regulators of energy use and amino acid availability within the cell.

The control of lipid metabolism by mRNA splicing in Drosophila

The storage of lipids is an evolutionarily conserved process that is important for the survival of organisms during shifts in nutrient availability. Triglycerides are stored in lipid droplets, but the mechanisms of how lipids are stored in these structures are poorly understood. Previous in vitro RNAi screens have implicated several components of the spliceosome in controlling lipid droplet formation and storage, but the in vivo relevance of these phenotypes is unclear. In this study, we identify specific members of the splicing machinery that are necessary for normal triglyceride storage in the Drosophila fat body. Decreasing the expression of the splicing factors U1-70K, U2AF38, U2AF50 in the fat body resulted in decreased triglyceride levels. Interestingly, while decreasing the SR protein 9G8 in the larval fat body yielded a similar triglyceride phenotype, its knockdown in the adult fat body resulted in a substantial increase in lipid stores. This increase in fat storage is due in part to altered splicing of the gene for the β-oxidation enzyme CPT1, producing an isoform with less enzymatic activity. Together, these data indicate a role for mRNA splicing in regulating lipid storage in Drosophila and provide a link between the regulation of gene expression and lipid homeostasis.

Contrasting Patterns of Community Assembly in the Stratified Water Column of Great Salt Lake, Utah

Phylogenetic examinations of communities sampled along geochemical gradients provide a framework for inferring the relative importance of niche-based ecological interactions (competition, environmental filtering) and neutral-based evolutionary interactions in structuring biodiversity. Great Salt Lake (GSL) in Utah exhibits strong spatial gradients due to both seasonal variation in freshwater input into the watershed and restricted fluid flow within North America's largest saline terminal lake ecosystem. Here, we examine the phylogenetic structure and composition of archaeal, bacterial, and eukaryal small subunit (SSU) rRNA genes sampled along a stratified water column (DWR3) in the south arm of GSL in order to infer the underlying mechanism of community assembly. Communities sampled from the DWR3 epilimnion were phylogenetically clustered (i.e., coexistence of close relatives due to environmental filtering) whereas those sampled from the DWR3 hypolimnion were phylogenetically overdispersed (i.e., coexistence of distant relatives due to competitive interactions), with minimal evidence for a role for neutral processes in structuring any assemblage. The shift from phylogenetically clustered to overdispersed assemblages was associated with an increase in salinity and a decrease in dissolved O2 (DO) concentration. Likewise, the phylogenetic diversity and phylogenetic similarity of assemblages was strongly associated with salinity or DO gradients. Thus, salinity and/or DO appeared to influence the mechanism of community assembly as well as the phylogenetic diversity and composition of communities. It is proposed that the observed patterns in the phylogenetic composition and structure of DWR3 assemblages are attributable to the meromictic nature of GSL, which prevents significant mixing between the epilimnion and the hypolimnion. This leads to strong physicochemical gradients at the halocline, which are capable of supporting a greater diversity. However, concomitant shifts in nutrient availability (e.g., DO) at and below the halocline drive competitive interactions leading to hypolimnion assemblages with minimal niche overlap.

Global change and the future of harmful algal blooms in the ocean

The frequency and intensity of harmful algal blooms (HABs) and phytoplankton community shifts toward toxic species have increased worldwide. Although most research has focused on eutrophication as the cause of this trend, many other global- and regional-scale anthropogenic influences may also play a role. Ocean acidification (high pCO2/low pH), green- house warming, shifts in nutrient availability, ratios, and speciation, changing exposure to solar irradiance, and altered salinity all have the potential to profoundly affect the growth and toxicity of these phytoplankton. Except for ocean acidification, the effects of these individual factors on harmful algae have been studied extensively. In this review, we summarize our understanding of the influence of each of these single factors on the physiological properties of important marine HAB groups. We then examine the much more limited literature on how rising CO2 together with these other concurrent environmental changes may affect these organisms, including what is pos- sibly the most critical property of many species: toxin production. New work with several diatom and dinoflagellate species suggests that ocean acidification combined with nutrient limitation or temperature changes may dramatically increase the toxicity of some harmful groups. This obser- vation underscores the need for more in-depth consideration of poorly understood interactions between multiple global change variables on HAB physiology and ecology. A key limitation of global change experiments is that they typically span only a few algal generations, making it difficult to predict whether they reflect likely future decadal- or century-scale trends. We con- clude by calling for thoughtfully designed experiments and observations that include adequate consideration of complex multivariate interactive effects on the long-term responses of HABs to a rapidly changing future marine environment.

Periconceptional influences on offspring sex ratio and placental responses

Maternal diet and secondary factors can strikingly influence fetal outcomes, including biasing offspring sex ratio and altering the molecular biological responses of the conceptus, namely within the placenta. Alterations in the in utero environment might also lead to profound developmental origin of health and disease (DOHaD) outcomes into adulthood, including increased risk for cardiovascular disease, obesity and cancer, with males in general being at greater risk for these diseases. Female mice maintained on a very high fat (VHF) diet birth more sons than those on a chow-based and low fat (LF), high carbohydrate diet, with the latter group producing more daughters. However, neither the underlying mechanisms that contribute to this shift in offspring sex ratio nor when they occur during pregnancy have been resolved. In this review, we consider the evidence that maternal diet and other factors influence secondary sex ratio in a variety of species, including humans, and discuss when this skewing might occur. Additionally, we examine how fetal sex and maternal diet influences gene expression patterns in the mouse placenta, which serves as the primary nutrient acquisition and communication organ between the mother and her developing pups. These adaptations to diet observed as changes in gene expression are likely to provide insight into how the placenta buffers the fetus proper from environmental shifts in nutrient availability during pregnancy and whether male and female conceptuses respond differently to such challenges.

Changes in nutrient availability from calcareous to acid wetland habitats with closely related brown moss species: increase instead of decrease in N and P

To test whether shifts in nutrient availability from calcareous to mineral-poor habitats could be a driving force in the evolution of seven closely related wetland brown mosses, we measured soil and vascular plant nutrients and conducted a laboratory incubation experiment with Swedish and some Dutch samples, in which net N and P-mineralization, respiration and microbial characteristics were measured. In spite of high respiration and microbial N, net N-mineralization appeared to be low for the calcareous Palustriella falcata and Scorpidium spp. Net N-mineralization significantly increased (and respiration and microbial N decreased) for the mineral-poor Sarmentypnum exannulatum, Straminergon stramineum and Warnstorfia fluitans, probably due to a decrease in microbial N-demand. Even though values were mainly negative, net P-mineralization showed a similar increase from calcareous to mineral-poor fens, probably due to lower precipitation of calcium phosphate. The calcareous habitat of the early wetland mosses may thus have been nutrient-poor instead of nutrient-rich. Adaptation to mineral-poor habitats, probably driven by expansion of mineral-poor wetlands when the boreal zone became colder and wetter, may have been associated with higher availability of ammonium and phosphate. However, this may have stimulated Sphagnum more than brown mosses, which may have been restricted to particular niches with perhaps some nitrification.