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Photocatalytic disinfection has long been used to combat pathogenic bacteria. However, the specific mechanism underlying photocatalytic disinfection and its corresponding targets remain unclear. In this study, an analysis of the potential mechanism underlying photocatalytic disinfection was performed based on integrated metabolic networks and transcriptional data. Two sets of RNA-seq data (wild type and a photocatalysis-resistant mutant mediated by titanium dioxide (TiO 2)) were processed to constrain the genome scale metabolic models (GSMM) of E. coli. By analyzing the metabolic network, the differential metabolic flux of every reaction was computed in constrained GSMM, and several significantly differential metabolic fluxes in reactions were extracted and analyzed. Most of these reactions were involved in the transmembrane transport of substances and occurred on the inner membrane or were an important component of the cell membrane. These results, which are consistent with the reported information, validated our analysis process. In addition, our work also identified other new and valuable metabolic pathways, such as the reaction ALCD2x, which has a great effect on the energy production process under bacterial anaerobic conditions. The DHAK reaction is also related to the metabolic process of ATP. These reactions with large differential metabolic fluxes merit further research. Additionally, to provide a strategy to address photocatalysis-resistant mutant bacteria, a metabolic compensation analysis was also performed. The metabolic compensation analysis results provided suggestions for a combined method that can effectively combat resistant bacteria. This method could also be used to explore the mechanisms of drug resistance in other microorganisms. Image 1 [ABSTRACT FROM AUTHOR]

Hypoxia is common in aquatic environments and has substantial effects on development, metabolism and survival of aquatic organisms. To understand the physiological effects of hypoxia and its dependence on temperature, metabolic rate ( M ̇ O 2 ) and cardiorespiratory function were studied in response to acute hypoxia (21 → 5 kPa) at different measurement temperatures (T a ; 4, 8 and 12 °C) in Salmo salar alevins that were incubated under normoxic conditions (P O 2 = 21 kPa) or following hypoxic acclimation (P O 2 = 10 kPa) as well as two different temperatures (4 °C or 8 °C). Hypoxic acclimation lead to a developmental delay manifested through slower yolk absorption. The general response to acute hypoxia was metabolic depression (~ 60%). Hypoxia acclimated alevins had higher M ̇ O 2 s when measured in normoxia than alevins acclimated to normoxia. M ̇ O 2 s were elevated to the same degree (~ 30% per 4 °C change) irrespective of T a . Under severe, acute hypoxia (~ 5 kPa) and irrespective of T a or acclimation, M ̇ O 2 s were similar between most groups. This suggests that despite different acclimation regimes, O 2 transport was limited to the same degree. While cardiorespiratory function (heart-, ventilation rate) was unchanged in response to acute hypoxia after normoxic acclimation, hypoxic acclimation led to cardiorespiratory changes predominantly in severe hypoxia, indicating earlier onset and plasticity of cardiorespiratory control mechanisms. Although M ̇ O 2 in normoxia was higher after hypoxic acclimation, at the respective acclimation P O 2 , M ̇ O 2 was similar in normoxia and hypoxia acclimated alevins. This is indicative of metabolic compensation to an intrinsic M ̇ O 2 at the acclimation condition in hypoxia-acclimated alevins after re-exposure to normoxia. [ABSTRACT FROM AUTHOR]

Most experiments examining acid-base regulation of chicken embryos have employed static, single time point measurements rather than dynamic, multiple time point measurements that might reveal additional components of developing acid-base regulation. Thus, we studied blood acid-base balance and hematology of day 15 chicken embryos under 24 h exposure to graded hypercapnia (1%–7% CO 2 ) accompanied by graded hypoxia (20% O 2 down to 13% O 2 ). Across all hypercapnic/hypoxic environments, respiratory acidosis occurred 2 h after exposure in proportion to the magnitude of hypercapnia. An additional metabolic alkalosis occurred in ≥16% O 2 , and metabolic acidosis in ≤14% O 2 . As exposure progressed, compensatory metabolic alkalosis occurred in all groups at 6 h, but partial metabolic compensation could not be preserved as hypoxia increased (≤18% O 2 ). Across all hypercapnic/hypoxic groups, hematocrit, mean corpuscular volume and red blood cell concentration significantly increased by 24 h, most likely due to hypoxia rather than hypercapnia. Overall, day 15 chicken embryos cannot maintain even partial compensation in their acid-base physiology after 24 h exposure to hypercapnic/hypoxic environments of ≥5% CO 2 + ≤15% O 2 . [ABSTRACT FROM AUTHOR]

Variable temperatures within a nest cause asynchronous development within clutches of freshwater turtle embryos, yet synchronous hatching occurs and is thought to be an important survival strategy for hatchlings. Metabolic compensation and circadian rhythms in heart rates of embryonic turtles indicate the potential of communication between embryos in a nest. Heart rates were used to identify metabolic circadian rhythms in clutches of an Australian freshwater turtle ( Chelodina longicollis ) and determine whether embryos metabolically compensate and hatch synchronously when incubated in asynchronous environments. The effects of a group environment during incubation on egg development and incubation period were also investigated during the final 3 weeks of development. Chelodina longicollis hatch synchronously and metabolically compensate so that less advanced embryos catch up to more advanced clutch-mates. Heart rates of embryos remained stable from week 4–7 in asynchronous (M = 89 bpm) and synchronous (M = 92 bpm) groups and declined in the final 2 weeks of incubation (M = 72 and 77 bpm). Circadian rhythms were present throughout development and diel heart rates of embryos in asynchronous groups showed less deviation from the mean (M = − 0.5 bpm) than synchronous groups (M = − 4 bpm). Eggs incubated in groups had a significantly shorter incubation period than eggs incubated individually. Phenotypic traits including size, performance, and growth of all hatchlings were not affected. Egg position within a turtle nest is important for coordinating development throughout incubation and facilitating synchronous hatching. [ABSTRACT FROM AUTHOR]

Time specific acid–base metabolic compensation and responses of hematological respiratory variables were measured in day 15 layer (Hyline) and broiler (Cornish Rock) chicken embryos during acute hypercapnic challenges (3, 6, 10 and 20% CO 2 ). Control acid–base status and hematology differed between two strains. Broiler embryos were relatively respiratory acidotic and had higher hematocrit (Hct) and hemoglobin concentration. The partial metabolic compensation for respiratory acidosis produced by ≤10% CO 2 exposures occurred in proportion to CO 2 concentrations in both strains, but metabolic compensation for 20% CO 2 respiratory acidosis was depressed at 2, 6 and 24 h, particularly in broiler embryos. Exposure to ≤10% CO 2 induced the same hematological responses across CO 2 concentrations; i.e., Hct and mean corpuscular volume (MCV) increased while RBC concentration remained unchanged. In response to 20% CO 2 exposure, Hct and MCV increased dramatically in both stains. Consequently, altered acid–base and hematology responses to 20% CO 2 exposure compared to ≤10% CO 2 suggest that the hypercapnic threshold to compensation for acidosis and regulation of hematology is >10% CO 2 . [ABSTRACT FROM AUTHOR]

In order to examine the effects of seasonal acclimation on mitochondrial metabolic functions and test tissue-specific pattern of the metabolic compensation within individuals of the southern catfish ( Silurus meridionalis Chen), rates of mitochondrial respiration and activities of cytochrome c oxidase (COX) in the heart, liver, kidney, brain and white muscle of this fish in the summer-acclimatized group (153.20 ± 1.66 g) and winter-acclimatized group (177.71 ± 3.04 g) were measured at seven assay temperatures (7.5, 12.5, 17.5, 22.5, 27.5, 32.5 and 37.5 °C), respectively. The results show that compensatory adjustments in state III respiratory rate and COX activity occur significantly in the heart, kidney and liver, but do not in the brain and white muscle, which suggest that the metabolic compensation of this fish in response to seasonal acclimation exhibits a tissue-specific pattern. The cold acclimation increases mitochondrial oxidative capacities in the heart, kidney and liver concomitantly with reducing their upper thermal limits of mitochondrial functions at acute warming and the thermal tolerance shifts in the same tissue-specific pattern as the metabolic compensation. When combining the effects of seasonal acclimation on mitochondrial oxidative capacity and organ mass, the metabolic compensation demonstrates an organ-specific pattern with four categories: over-compensation in the heart, complete compensation in the kidney, partial compensation in the liver and no compensation in the brain. The organ-specific pattern of metabolic compensation might be a trade-off strategy of the performance adjustments in the seasonal acclimation for this fish to maximize its fitness. [ABSTRACT FROM AUTHOR]

Abstract: In day 15 chicken embryos, we determined the time course responses of acid–base balance and hematological respiratory variables during 24h exposure to 15, 20, 40 or 90% O2, in the presence of 5% CO2. Hypercapnic respiratory acidosis was initially (2h) only slightly (∼20%) compensated by metabolic alkalosis in normoxic/hyperoxic embryos. After 6h, respiratory acidosis was partially (∼40–50%) compensated not only in normoxic/hyperoxic embryos, but also in hypoxic embryos. However, partial metabolic compensation in 15% O2 could not be preserved after 24h. Preservation of metabolic compensation required oxygen concentration ([O2]) above 20%, but the magnitude of partial metabolic compensation was unrelated to [O2]. Hematocrit (Hct), together with mean corpuscular volume (MCV), markedly increased in hypercapnic hypoxia, and was maintained at 24h due to a subsequent increase in red blood cell concentration ([RBC]). In contrast, Hct, together with MCV, decreased in hypercapnic normoxia/hyperoxia accompanied by a subsequent decrease in [RBC] at 24h. Regulation of variables takes place similarly irrespective of environmental [O2] above 20%, matching acid–base regulation. [Copyright &y& Elsevier]