Substrate Supply Research Articles

Ambient temperature, heat stress and fetal growth: A review of placenta-mediated mechanisms

Pregnancy is increasingly considered a period of vulnerability for extreme heat exposure. Multiple lines of evidence support that heat stress is associated with placental insufficiency, poor fetal growth and decreased birth weight. In this narrative review, we first summarize evidence linking ambient temperature or experimentally-induced heat stress with fetal and placental growth outcomes in humans, ruminants and murine species. We then synthesize the literature on putative underlying biological pathways with a focus on the placenta. Reviewed mechanisms include: reduced uterine-placental blood flow, impaired supply of metabolic substrates to the fetus, activation of the maternal stress-response system, and disruption of other endocrine and immune system endpoints. Taken together, this body of evidence supports that exposure to extreme ambient heat likely has adverse consequences for placental development and function. However, research investigating placenta-mediated pathophysiological mechanisms in humans remains extremely limited.

Rutin forestalls dysregulated cardiac bioenergetics in bisphenol A and dibutyl phthalate-exposed rats through PPARα and AMPK modulation

Objectives: Proper cardiac function is greatly dependent on adequate supply and metabolism of energy substrates. Environmental pollutants exposure including plasticizers can trigger adverse cardiac metabolic events. This study was designed to investigate the ameliorative effect of rutin (Rt) on dysregulated cardiac energy metabolism in plasticizer-exposed rats. Materials and Methods: Forty-two rats were randomised into seven groups (n = 6): Control (0.1% dimethyl sulfoxide), bisphenol A (BPA, 25 mg/kg, p.o), dibutyl phthalate (DBP, 25 mg/kg, p.o), BPA + Rt 25 mg/kg, Rt 50 mg/kg, DBP + Rt (25 mg/kg, Rt 50 mg/kg), BPA + DBP and BPA + DBP + Rt, daily for 21 days. Results: BPA and DBP exposure increased plasma glucose, reduced insulin, and increased plasma and cardiac free fatty-acid. Cardiac glucose-6-phosphate level, hexokinase and pyruvate dehydrogenase activities increased in DBP while BPA reduced these variables. Cardiac glucose transporter-4 expression was reduced in BPA group, while cardiac peroxisome proliferator-activated receptor-alpha (PPARα) and AMP-activated protein kinase (AMPK) expression increased in BPA and DBP-treated rats. However, Rt administration prevents impaired cardiac bioenergetics and glucometabolic regulation. Conclusion: Summarily, Rt improves BPA and DBP-impaired cardiac bioenergetics through PPARα and AMPK modulation.

Variation in epibiotic bacteria on two squat lobster species of Munidopsidae.

The relationships between epibiotic bacteria on deep-sea hosts and host lifestyle factors are of particular interest in the field of deep-sea chemoautotrophic environmental adaptations. The squat lobsters Shinkaia crosnieri and Munidopsis verrilli are both dominant species in cold-seep ecosystems, and they have different distributions and feeding behaviors. These species may have evolved to have distinct epibiotic microbiota. Here, we compared the epibiotic bacterial communities on the M. verrilli carapace (MVcarapace), S. crosnieri carapace (SCcarapace), and S. crosnieri ventral plumose setae (SCsetae). The epibiotic bacteria on SCsetae were dense and diverse and had a multi-layer configuration, while those on MVcarapace and SCcarapace were sparse and had a monolayer configuration. Chemoautotrophic bacteria had the highest relative abundance in all epibiotic bacterial communities. The relative abundance of amplicon sequence variant 3 (ASV3; unknown species in order Thiotrichales), which is associated with sulfide oxidation, was significantly higher in SCsetae than MVcarapace and SCcarapace. Thiotrichales species seemed to be specifically enriched on SCsetae, potentially due to the synthetic substrate supply, adhesion preference, and host behaviors. We hypothesize that the S. crosnieri episymbionts use chemical fluxes near cold seeps more efficiently, thereby supporting the host's nutrient strategies, resulting in a different distribution of the two species of squat lobster.

Lactate as a supplemental fuel for synaptic transmission and neuronal network oscillations: Potentials and limitations.

Lactate shuttled from the blood circulation, astrocytes, oligodendrocytes or even activated microglia (resident macrophages) to neurons has been hypothesized to represent a major source of pyruvate compared to what is normally produced endogenously by neuronal glucose metabolism. However, the role of lactate oxidation in fueling neuronal signaling associated with complex cortex function, such as perception, motor activity, and memory formation, is widely unclear. This issue has been experimentally addressed using electrophysiology in hippocampal slice preparations (ex vivo) that permit the induction of different neural network activation states by electrical stimulation, optogenetic tools or receptor ligand application. Collectively, these studies suggest that lactate in the absence of glucose (lactate only) impairs gamma (30-70 Hz) and theta-gamma oscillations, which feature high energy demand revealed by the cerebral metabolic rate of oxygen (CMRO2, set to 100%). The impairment comprises oscillation attenuation or moderate neural bursts (excitation-inhibition imbalance). The bursting is suppressed by elevating the glucose fraction in energy substrate supply. By contrast, lactate can retain certain electric stimulus-induced neural population responses and intermittent sharp wave-ripple activity that features lower energy expenditure (CMRO2 of about 65%). Lactate utilization increases the oxygen consumption by about 9% during sharp wave-ripples reflecting enhanced adenosine-5'-triphosphate (ATP) synthesis by oxidative phosphorylation in mitochondria. Moreover, lactate attenuates neurotransmission in glutamatergic pyramidal cells and fast-spiking, γ-aminobutyric acid (GABA)ergic interneurons by reducing neurotransmitter release from presynaptic terminals. By contrast, the generation and propagation of action potentials in the axon is regular. In conclusion, lactate is less effective than glucose and potentially detrimental during neural network rhythms featuring high energetic costs, likely through the lack of some obligatory ATP synthesis by aerobic glycolysis at excitatory and inhibitory synapses. High lactate/glucose ratios might contribute to central fatigue, cognitive impairment, and epileptic seizures partially seen, for instance, during exhaustive physical exercise, hypoglycemia and neuroinflammation.

Placement of Extracranial Stimulating Electrodes and Measurement of Cerebral Blood Flow and Intracranial Electrical Fields in Anesthetized Mice.

The detection of cerebral blood flow (CBF) responses to various forms of neuronal activation is critical for understanding dynamic brain function and variations in the substrate supply to the brain. This paper describes a protocol for measuring CBF responses to transcranial alternating current stimulation (tACS). Dose-response curves are estimated both from the CBF change occurring with tACS (mA) and from the intracranial electric field (mV/mm). We estimate the intracranial electrical field based on the different amplitudes measured by glass microelectrodes within each side of the brain. In this paper, we describe the experimental setup, which involves using either bilateral laser Doppler (LD) probes or laser speckle imaging (LSI) to measure the CBF; as a result, this setup requires anesthesia for the electrode placement and stability. We present a correlation between the CBF response and the current as a function of age, showing a significantly larger response at higher currents (1.5 mA and 2.0 mA) in young control animals (12-14 weeks) compared to older animals (28-32 weeks) (p < 0.005 difference). We also demonstrate a significant CBF response at electrical field strengths <5 mV/mm, which is an important consideration for eventual human studies. These CBF responses are also strongly influenced by the use of anesthesia compared to awake animals, the respiration control (i.e., intubated vs. spontaneous breathing), systemic factors (i.e., CO2), and local conduction within the blood vessels, which is mediated by pericytes and endothelial cells. Likewise, more detailed imaging/recording techniques may limit the field size from the entire brain to only a small region. We describe the use of extracranial electrodes for applying tACS stimulation, including both homemade and commercial electrode designs for rodents, the concurrent measurement of the CBF and intracranial electrical field using bilateral glass DC recording electrodes, and the imaging approaches. We are currently applying these techniques to implement a closed-loop format for augmenting the CBF in animal models of Alzheimer's disease and stroke.

High Sensitivity Surface Defect Inspection of SiC and SmartSiC&lt;sup&gt;TM&lt;/sup&gt; Substrates Using a DUV Laser-Based System

SmartSiCTM technology enables the supply of cost-effective and high-quality substrates to support the manufacturing of Silicon Carbide (SiC) Power Devices and the transition to High Volume Manufacturing (HVM) [1]. As detailed in [2] SmartSiCTM is prepared using a poly-crystalline handle wafer, it combines the benefit from both an optimized high quality epi-ready 4H-SiC layer and an ultra high conductivity handle material. Smart CutTM technology can be extended to SiC 200mm substrates and first SmartSiCTM 200mm sample has been prepared [2].SmartSiCTM substrates crystal quality is inherited by donor wafers [1, 2] and do not require a systematic control, enabling a new defects monitoring strategy, focusing on surface defects.This paper describes how a commercially available DUV inspection system was utilized for high sensitivity, high-throughput inspections of 150 and 200 mm 4H-SiC and SmartSiCTM substrates, for the HVM environment. The KLA Surfscan® SP A2 unpatterned wafer inspection system offers the opportunity to complement other inspection technologies to optimize SiC substrate defect control, with low threshold detection, below 150 nm.

Insights into the Functional Components in Wheat Grain: Spatial Pattern, Underlying Mechanism and Cultivation Regulation.

Wheat is a staple crop; its production must achieve both high yield and good quality due to worldwide demands for food security and better quality of life. It has been found that the grain qualities vary greatly within the different layers of wheat kernels. In this paper, the spatial distributions of protein and its components, starch, dietary fiber, and microelements are summarized in detail. The underlying mechanisms regarding the formation of protein and starch, as well as spatial distribution, are discussed from the views of substrate supply and the protein and starch synthesis capacity. The regulating effects of cultivation practices on gradients in composition are identified. Finally, breakthrough solutions for exploring the underlying mechanisms of the spatial gradients of functional components are presented. This paper will provide research perspectives for producing wheat that is both high in yield and of good quality.

Gene and protein expression and metabolic flux analysis reveals metabolic scaling in liver ex vivo and in vivo.

Metabolic scaling, the inverse correlation of metabolic rates to body mass, has been appreciated for more than 80 years. Studies of metabolic scaling have largely been restricted to mathematical modeling of caloric intake and oxygen consumption, and mostly rely on computational modeling. The possibility that other metabolic processes scale with body size has not been comprehensively studied. To address this gap in knowledge, we employed a systems approach including transcriptomics, proteomics, and measurement of in vitro and in vivo metabolic fluxes. Gene expression in livers of five species spanning a 30,000-fold range in mass revealed differential expression according to body mass of genes related to cytosolic and mitochondrial metabolic processes, and to detoxication of oxidative damage. To determine whether flux through key metabolic pathways is ordered inversely to body size, we applied stable isotope tracer methodology to study multiple cellular compartments, tissues, and species. Comparing C57BL/6 J mice with Sprague-Dawley rats, we demonstrate that while ordering of metabolic fluxes is not observed in in vitro cell-autonomous settings, it is present in liver slices and in vivo. Together, these data reveal that metabolic scaling extends beyond oxygen consumption to other aspects of metabolism, and is regulated at the level of gene and protein expression, enzyme activity, and substrate supply.

Influence of accelerated arterial ageing in growth restricted cohorts on adult-onset cardiovascular diseases.

Epidemiologists have long documented higher risk of adult-onset cardiovascular diseases (CVD) such as stroke, hypertension and coronary artery disease) and mortality from circulatory causes in low birth weight cohorts (poor in utero substrate supply). Utero-placental insufficiency and in utero hypoxemic state induced alterations in arterial structure and compliance are important initiating factors for adult-onset hypertension. The mechanistic links between fetal growth restriction and CVD include decreased arterial wall elastin/collagen ratio, endothelial dysfunction and heightened renin-angiotensin-aldosterone-system (RAAS). Systemic arterial thickness on fetal ultrasound and vascular changes in placental histopathology in growth restricted cohorts indicate fetal/developmental origins of adult-onset circulatory diseases. Similar findings of impaired arterial compliance have been noticed across age-groups (neonates through to adults). Such changes augment what occurs as 'normal arterial ageing', resulting in accelerated arterial ageing. Data from animal models suggest that hypoxemia-associated vascular adaptations enacted in utero are region specific, reflecting long-term vascular pathology. In this review we explore the influence of birthweight and prematurity on blood pressure and arterial stiffness, demonstrating impaired arterial dynamics in growth restricted cohorts across age-groups, explain how early arterial ageing influences adult-onset CVDs, describe pathophysiology data from experimental models and finally, discuss interventions which may influence ageing by way of altering various cellular and molecular mechanisms of arterial ageing. Age-appropriate interventions which have noted efficacy include prolonged breastfeeding and high polyunsaturated fatty acids dietary intake. Targeting the RAAS seems a promising approach. New data indicates activation of Sirtuin 1 and maternal resveratrol may have beneficial effects.

The metabolic state of the heart regulates mitochondrial supercomplex abundance in mice

Mitochondrial supercomplexes are observed in mammalian tissues with high energy demand and may influence metabolism and redox signaling. Nevertheless, the mechanisms that regulate supercomplex abundance remain unclear. In this study, we examined the composition of supercomplexes derived from murine cardiac mitochondria and determined how their abundance changes with substrate provision or by genetically induced changes to the cardiac glucose-fatty acid cycle. Protein complexes from digitonin-solubilized cardiac mitochondria were resolved by blue-native polyacrylamide gel electrophoresis and were identified by mass spectrometry and immunoblotting to contain constituents of Complexes I, III, IV, and V as well as accessory proteins involved in supercomplex assembly and stability, cristae architecture, carbohydrate and fat oxidation, and oxidant detoxification. Respiratory analysis of high molecular mass supercomplexes confirmed the presence of intact respirasomes, capable of transferring electrons from NADH to O2. Provision of respiratory substrates to isolated mitochondria augmented supercomplex abundance, with fatty acyl substrate (octanoylcarnitine) promoting higher supercomplex abundance than carbohydrate-derived substrate (pyruvate). Mitochondria isolated from transgenic hearts that express kinase-deficient 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase (GlycoLo), which decreases glucose utilization and increases reliance on fatty acid oxidation for energy, had higher mitochondrial supercomplex abundance and activity compared with mitochondria from wild-type or phosphatase-deficient 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase-expressing hearts (GlycoHi), the latter of which encourages reliance on glucose catabolism for energy. These findings indicate that high energetic reliance on fatty acid catabolism bolsters levels of mitochondrial supercomplexes, supporting the idea that the energetic state of the heart is regulatory factor in supercomplex assembly or stability.

Enhancing nitrogen removal of carbon-limited municipal wastewater in step-feed biofilm batch reactor through integration of anammox

The biological nitrogen removal of municipal wastewater was successfully improved by integrating anammox in a step-feed sequencing biofilm batch reactor. Despite fluctuating influent carbon to nitrogen ratio (1.9–5.1) and decreasing temperature (24.1–16.3 ℃), nitrogen removal efficiency of 95.9 ± 1.4 % and nitrogen removal rate of 0.23 ± 0.02 kg N/(m3·d) were successfully maintained without requirement of external carbon sources. The advanced removal performance was mainly attributed to the enhanced anammox. Anammox bacteria presented a high relative abundance (42.9% in biofilms, 1.5% in flocs) and anammox activity was as high as 5.42 ± 0.12 mg N/(g volatile suspended solids·h). Further analysis suggested that flexible control of influent organic and ammonium through step-feeding could provide multiple substrate supply for anammox reaction, potentially resulting in stable combination of anammox with hybrid-nitrite-shunt processes. Overall, this study provides a promising anammox-related application with simple-control step-feed strategy for enhanced and stable nitrogen removal from carbon-limited municipal wastewater.

Revealed mechanism of micron-pore size of 3D bio-anode on the behavior of biofilm and system performance in microbial electrochemical system

Microbial electrochemical systems (MESs) are widely studied as a promising technology for recovering bioenergy from wastewater. The anode has a great impact on the performance of the MES and more and more three-dimensional (3D) porous anodes are constructed to improve the bioenergy recovery and the system performance. However, the establishment of suitable pore sizes for MES 3D anodes and the effect of different micron-pore sizes on system performance has not been thoroughly studied. Here, we found the change in pore size affected the start-up time and bio-electrochemical performance by affecting the physical characteristics (surface area and porosity) and mass transfer of the 3D anode. The introduction of pore size on 3D anodes led to the mass transfer limitation of substrate and buffer species, and this phenomenon was severe as pore size decreased. The mass transfer limitation of substrate supply inside the pore imposed a selective pressure to enrich Geobacter from 18.45% to 72.96% when the pore size decreased from 800 μm to 100 μm. However, the acidification brought by the mass transfer limitation of the buffer species affected the activity of microorganisms and played a more important role leading to the 3D anode with 800 μm pore size achieving higher power densities (4593.3 ± 78.2 mW/m3), 1.7 times that of the 3D anode with 100 μm pore size (2782.6 ± 79.2 mW/m3). The present research provides a reference for the construction of high-performance 3D structured anodes and an in-depth understanding of the effect of pore size on system performance.

How mitochondria showcase evolutionary mechanisms and the importance of oxygen

Darwinian evolution can be simply stated: natural selection of inherited variations increasing differential reproduction. However, formulated thus, links with biochemistry, cell biology, ecology, and population dynamics remain unclear. To understand interactive contributions of chance and selection, higher levels of biological organization (e.g., endosymbiosis), complexities of competing selection forces, and emerging biological novelties (such as eukaryotes or meiotic sex), we must analyze actual examples. Focusing on mitochondria, I will illuminate how biology makes sense of life's evolution, and the concepts involved. First, looking at the bacterium - mitochondrion transition: merging with an archaeon, it lost its independence, but played a decisive role in eukaryogenesis, as an extremely efficient aerobic ATP generator and internal ROS source. Second, surveying later mitochondrion adaptations and diversifications illustrates concepts such as constructive neutral evolution, dynamic interactions between endosymbionts and hosts, the contingency of life histories, and metabolic reprogramming. Without oxygen, mitochondria disappear; with (intermittent) oxygen diversification occurs in highly complex ways, especially upon (temporary) phototrophic substrate supply. These expositions show the Darwinian model to be a highly fruitful paradigm.

Quantitative discrimination of algae multi-impacts on N2O emissions in eutrophic lakes: Implications for N2O budgets and mitigation

It is generally accepted that eutrophic lakes significantly contribute to nitrous oxide (N2O) emissions. However, how these emissions are affected by the formation, disappearance, and mechanisms of algal blooms in these lakes has not been systematically investigated. This study examined and determined the relative contribution of spatiotemporal N2O production pathways in hypereutrophic Lake Taihu. Synchronously, the multi-impacts of algae on N2O production and release potential were measured in the field and in microcosms using isotope ratios of oxygen (δ18O) and bulk nitrogen (δ15N) to N2O and to intramolecular 15N site preference (SP). Results showed that N2O production in Lake Taihu was derived from microbial effects (nitrification and incomplete denitrification) and water air exchanges. N2O production was also affected by the N2O reduction process. The mean dissolved N2O concentrations in the water column during the pre-outbreak, outbreak, and decay stages of algae accumulation were almost the same (0.05 μmol·L–1), which was 2–10 times higher than in lake areas algae was not accumulating. However, except for the central lake area, all surveyed areas (with and without accumulated algae) displayed strong release potential and acted as the emission source because of dissolved N2O supersaturation in the water column. The mean N2O release fluxes during the pre-outbreak, outbreak, and decay stages of algae accumulation areas were 17.95, 26.36, and 79.32 μmol·m–2·d–1, respectively, which were 2.0–7.5 times higher than the values in the non-algae accumulation areas. In addition, the decay and decomposition of algae released large amounts of nutrients and changed the physiochemical properties of the water column. Additionally, the increased algae biomass promoted N2O release and improved the proportion of N2O produced via denitrification process to being 9.8–20.4% microbial-derived N2O. This proportion became higher when the N2O consumption during denitrification was considered as evidenced by isotopic data. However, when the algae biomass was excessive in hypereutrophic state, the algae decomposition also consumed a large amount of oxygen, thus limiting the N2O production due to complete denitrification as well as due to the limited substrate supply of nitrate by nitrification in hypoxic or anoxic conditions. Further, the excessive algae accumulation on the water surface reduced N2O release fluxes via hindering the migration of the dissolved N2O into the atmosphere. These findings provide a new perspective and understanding for accurately evaluating N2O release fluxes driven by algae processes in eutrophic lakes.

Patterns and drivers of anaerobic nitrogen transformations in sediments of thermokarst lakes.

Significant attention has been given to the way in which the soil nitrogen (N) cycle responds to permafrost thaw in recent years, yet little is known about anaerobic N transformations in thermokarst lakes, which account for more than one-third of thermokarst landforms across permafrost regions. Based on the N isotope dilution and tracing technique, combined with qPCR and high-throughput sequencing, we presented large-scale measurements of anaerobic N transformations of sediments across 30 thermokarst lakes over the Tibetan alpine permafrost region. Our results showed that gross N mineralization, ammonium immobilization, and dissimilatory nitrate reduction rates in thermokarst lakes were higher in the eastern part of our study area than in the west. Denitrification dominated in the dissimilatory nitrate reduction processes, being two and one orders of magnitude higher than anaerobic ammonium oxidation (anammox) and dissimilatory nitrate reduction to ammonium (DNRA), respectively. The abundances of the dissimilatory nitrate reduction genes (nirK, nirS, hzsB, and nrfA) exhibited patterns consistent with sediment N transformation rates, while α diversity did not. The inter-lake variability in gross N mineralization and ammonium immobilization was dominantly driven by microbial biomass, while the variability in anammox and DNRA was driven by substrate supply and organic carbon content, respectively. Denitrification was jointly affected by nirS abundance and organic carbon content. Overall, the patterns and drivers of anaerobic N transformation rates detected in this study provide a new perspective on potential N release, retention, and removal upon the formation and development of thermokarst lakes.

Different responses of the gross nitrification rate to N enrichment in topsoil and subsoil

Nitrogen (N) deposition has continually increased since the industrial revolution and its rate varies widely around the world. The dynamic of soil nitrification under N enrichment affects nitrous oxide (N2O) emissions and nitrate (NO3−) leaching which are related to current environmental problems. However, the response of soil nitrification, particularly in subsoil, to a N enrichment gradient and the mechanisms involved have not been well studied. In this study, the gross nitrification rates (GNRs) and relevant abiotic and biotic factors along a N addition gradient in a field were determined at three soil depths using a 15N-labeling method. The GNR in topsoil (0–10 cm) followed a bell-shaped curve as the N addition rate increased. The GNR in subsoil (10–20 and 20–40 cm) linearly decreased as the N addition rate increased. The GNR positively correlated with the ammonia-oxidizing bacteria (AOB) abundance in topsoil (P < 0.05) and the gross mineralization rate in subsoil (P < 0.05). The results indicated that changes in the AOB abundance contributed to the bell-shaped pattern of GNR in the topsoil, and the decrease in mineralization rate contributed to the decrease in GNR with N enrichment by reducing substrate supply in the subsoil. The different responses of soil nitrification to N enrichment at different soil depths and the mechanisms involved should be taken into consideration in biogeochemical models to better predict the soil N cycling in the context of N enrichment.

Steering the product spectrum in high-pressure anaerobic processes: CO2 partial pressure as a novel tool in biorefinery concepts

BackgroundElevated CO2 partial pressure (pCO2) has been proposed as a potential steering parameter for selective carboxylate production in mixed culture fermentation. It is anticipated that intermediate product spectrum and production rates, as well as changes in the microbial community, are (in)directly influenced by elevated pCO2. However, it remains unclear how pCO2 interacts with other operational conditions, namely substrate specificity, substrate-to-biomass (S/X) ratio and the presence of an additional electron donor, and what effect pCO2 has on the exact composition of fermentation products. Here, we investigated possible steering effects of elevated pCO2 combined with (1) mixed substrate (glycerol/glucose) provision; (2) subsequent increments in substrate concentration to increase the S/X ratio; and (3) formate as an additional electron donor.ResultsMetabolite predominance, e.g., propionate vs. butyrate/acetate, and cell density, depended on interaction effects between pCO2–S/X ratio and pCO2–formate. Individual substrate consumption rates were negatively impacted by the interaction effect between pCO2–S/X ratio and were not re-established after lowering the S/X ratio and adding formate. The product spectrum was influenced by the microbial community composition, which in turn, was modified by substrate type and the interaction effect between pCO2–formate. High propionate and butyrate levels strongly correlated with Negativicutes and Clostridia predominance, respectively. After subsequent pressurized fermentation phases, the interaction effect between pCO2–formate enabled a shift from propionate towards succinate production when mixed substrate was provided.ConclusionsOverall, interaction effects between elevated pCO2, substrate specificity, high S/X ratio and availability of reducing equivalents from formate, rather than an isolated pCO2 effect, modified the proportionality of propionate, butyrate and acetate in pressurized mixed substrate fermentations at the expense of reduced consumption rates and increased lag-phases. The interaction effect between elevated pCO2 and formate was beneficial for succinate production and biomass growth with a glycerol/glucose mixture as the substrate. The positive effect may be attributed to the availability of extra reducing equivalents, likely enhanced carbon fixating activity and hindered propionate conversion due to increased concentration of undissociated carboxylic acids.

Salinity determines performance, functional populations, and microbial ecology in consortia attenuating organohalide pollutants.

Organohalide pollutants are prevalent in coastal regions due to extensive intervention by anthropogenic activities, threatening public health and ecosystems. Gradients in salinity are a natural feature of coasts, but their impacts on the environmental fate of organohalides and the underlying microbial communities remain poorly understood. Here we report the effects of salinity on microbial reductive dechlorination of tetrachloroethene (PCE) and polychlorinated biphenyls (PCBs) in consortia derived from distinct environments (freshwater and marine sediments). Marine-derived microcosms exhibited higher halotolerance during PCE and PCB dechlorination, and a halotolerant dechlorinating culture was enriched from these microcosms. The organohalide-respiring bacteria (OHRB) responsible for PCE and PCB dechlorination in marine microcosms shifted from Dehalococcoides to Dehalobium when salinity increased. Broadly, lower microbial diversity, simpler co-occurrence networks, and more deterministic microbial community assemblages were observed under higher salinity. Separately, we observed that inhibition of dechlorination by high salinity could be attributed to suppressed viability of Dehalococcoides rather than reduced provision of substrates by syntrophic microorganisms. Additionally, the high activity of PCE dechlorinating reductive dehalogenases (RDases) in in vitro tests under high salinity suggests that high salinity likely disrupted cellular components other than RDases in Dehalococcoides. Genomic analyses indicated that the capability of Dehalobium to perform dehalogenation under high salinity was likely owing to the presence of genes associated with halotolerance in its genomes. Collectively, these mechanistic and ecological insights contribute to understanding the fate and bioremediation of organohalide pollutants in environments with changing salinity.

Differential Effects of Viruses on the Growth Efficiency of Freshwater Bacterioplankton in Eutrophic Relative to Non-Eutrophic Lakes

In aquatic environments, the consensus of viral impact on bacterial carbon metabolism with the nutrient environment as an important axis is limited. Henceforth, we explored the viral regulation of carbon-based bacterial growth efficiency (BGE) in a set of freshwater systems from French Massif Central, which were broadly classified based on two trophic statuses: eutrophic and non-eutrophic lakes. Comparative analysis showed that microbial abundances (viruses and bacteria) were 3-fold higher in eutrophic compared with non-eutrophic lakes, and so were bacterial production and viral lytic infection. The observed variability in BGE (10-60%) was explained by the uncoupling between bacterial respiration and production. Viruses through selective lysis of susceptible host communities had an antagonistic impact on BGE in the eutrophic lakes, whereas the release of substrates via viral shunt exerted a synergistic influence on the carbon metabolism of non-targeted host populations in non-eutrophic lakes. The decisive effect of the two individual processes (i.e., lysis and substrate release) on BGE was supported by regressions of bacterial abundance as a function of bacterial production, which is considered as a proxy of top-down processes. The role of viruses through their negative impact via mortality and positive impact via substrate supply can eventually have implications on carbon transfer through bacterioplankton in freshwaters.

Review of ESPEN-2021 Practice Guidelines for Patients with Cancer. Part 2: Interventions Relevant to Specific Patient Categories

This study further discussed the 2021 ESPEN practical recommendations for nutritional support in oncology. The updated version of the 2021 ESPEN practice guidelines differs slightly from the 2017 version and contains flowcharts to facilitate the use of the guidelines in clinical practice, which is also relevant for domestic healthcare. ESPEN-2021 Clinical Guidelines, which offer practical solutions in all areas of oncology, are significant to both oncologists and allied specialists working in oncology. The second part of the review discusses particular issues of nutritional support for patients with cancer and analyzes the domestic experience of their use. The review provides the main protocols for artificial nutrition in surgery, during irradiation, and in drug therapy in patients in remission and at the palliative stage and proves the need to maintain physical activity in patients with cancer. The presented practical guidance allows organizing an adequate supply of nutrient substrates to patients with cancer receiving various types of anticancer treatment, in remission, and at the stage of palliative care.