Enzymes Of Intermediary Metabolism Research Articles

Use of black soldier fly (Hermetia illucens) larvae meal in diets for gilthead seabream juveniles: Effects on growth-related gene expression, intermediary metabolism, digestive enzymes, and gut microbiota modulation

A study was conducted to evaluate the effects of dietary inclusion of defatted Hermetia illucens larvae meal (HM) on the expression of growth-related genes, plasma metabolites, activity of intermediary metabolism enzymes, and gut microbiota modulation in gilthead seabream (Sparus aurata) juveniles. Four experimental diets were formulated (43% crude protein, 18% crude lipids) with increasing levels of defatted HM: 0 (HM0), 15 (HM15), 30 (HM30), and 45% (HM45) replacing fishmeal (included at 34% in the control diet) at 0, 22, 60, and 100%, respectively. Fish were fed these diets for 67 days. At the end of the trial, the expression of muscle growth hormone receptors (ghr1 and ghr2), insulin-like growth factors (igf1 and igf2), cathepsins (cts-a and cts-b), and myogenic determination factor 1 (myod1) were not affected, while a downregulation of myogenic determination factor 2 (myod2) and upregulation of myostatin (mstn) was observed with HM inclusion. Plasma metabolites profile was unaffected by diet composition, except for a linear decrease trend in total lipids. A linear increase of liver alanine aminotransferase (ALT) and glutamate dehydrogenase (GDH) activity and a linear decrease of glucose 6-phosphate dehydrogenase (G6PDH), malic enzyme (ME), and (FAS) activity were observed with HM inclusion. The activity of β-hydroxy acyl-CoA dehydrogenase (HOAD) followed a quadratic trend, being higher in fish fed with diet HM15 than in the control. Likewise, amylase, trypsin, and chymotrypsin activity were higher in the posterior intestine of fish fed with diet HM15. Digesta of fish fed the HM-containing diets showed an increase in the number of operational taxonomic units, microbial richness, and diversity. Conversely, a reduction in these indexes was observed in the mucosa. Among the identified bacteria, Firmicutes represented the predominant phyla. The inclusion of HM increased the abundance of Oceanobacillus, Lederbergia, Bacillus, and Corynebacterium in the digesta while Lactobacillus and Caldalkalibacillus abundance was reduced. Overall, total FM replacement with defatted HM had no major effects on plasma metabolites and muscle growth-related genes but induced a few differences in intermediary metabolism and digestive enzymes activity. HM inclusion improved gut digesta microbiota richness and diversity, promoting the growth of potential beneficial bacteria.

Formation of a stable RNase Y-RicT (YaaT) complex requires RicA (YmcA) and RicF (YlbF).

In Bacillus subtilis, the RicT (YaaT), RicA (YmcA), and RicF (YlbF) proteins, which form a stable ternary complex, are needed together with RNase Y (Rny) to cleave and thereby stabilize several key transcripts encoding enzymes of intermediary metabolism. We show here that RicT, but not RicA or RicF, forms a stable complex with Rny and that this association requires the presence of RicA and RicF. We propose that RicT is handed off from the ternary complex to Rny. We show further that the two iron-sulfur clusters carried by the ternary Ric complex are required for the formation of the stable RicT-Rny complex. We demonstrate that proteins of the degradosome-like network of B. subtilis, which also interact with Rny, are dispensable for processing of the gapA operon. Thus, Rny participates in distinct RNA-related processes, determined by its binding partners, and a RicT-Rny complex is likely the functional entity for gapA mRNA maturation. IMPORTANCE The action of nucleases on RNA is universal and essential for all forms of life and includes processing steps that lead to the mature and functional forms of certain transcripts. In Bacillus subtilis, it has been shown that key transcripts for energy-producing steps of glycolysis, for nitrogen assimilation, and for oxidative phosphorylation, all of them crucial processes of intermediary metabolism, are cleaved at specific locations, resulting in mRNA stabilization. The proteins required for these cleavages in B. subtilis [Rny (RNase Y), RicA (YmcA), RicF (YlbF), and RicT (YaaT)] are broadly conserved among the firmicutes, including several important pathogens, hinting that regulatory mechanisms they control may also be conserved. Several aspects of these regulatory events have been explored: phenotypes associated with the absence of these proteins have been described, the impact of these absences on the transcriptome has been documented, and there has been significant exploration of the biochemistry and structural biology of Rny and the Ric proteins. The present study further advances our understanding of the association of Ric proteins and Rny and shows that a complex of Rny with RicT is probably the entity that carries out mRNA maturation.

The RNA-binding protein landscapes differ between mammalian organs and cultured cells

System-wide approaches have unveiled an unexpected breadth of the RNA-bound proteomes of cultured cells. Corresponding information regarding RNA-binding proteins (RBPs) of mammalian organs is still missing, largely due to technical challenges. Here, we describe ex vivo enhanced RNA interactome capture (eRIC) to characterize the RNA-bound proteomes of three different mouse organs. The resulting organ atlases encompass more than 1300 RBPs active in brain, kidney or liver. Nearly a quarter (291) of these had formerly not been identified in cultured cells, with more than 100 being metabolic enzymes. Remarkably, RBP activity differs between organs independent of RBP abundance, suggesting organ-specific levels of control. Similarly, we identify systematic differences in RNA binding between animal organs and cultured cells. The pervasive RNA binding of enzymes of intermediary metabolism in organs points to tightly knit connections between gene expression and metabolism, and displays a particular enrichment for enzymes that use nucleotide cofactors. We describe a generically applicable refinement of the eRIC technology and provide an instructive resource of RBPs active in intact mammalian organs, including the brain.

Effects of Fasting on Intermediary Metabolism Enzymes in the Liver and Muscle of Rainbow Trout

Fish can go through periods of feed deprivation, either due to natural causes influenced by temperature or management techniques in animal production, affecting their energy metabolism differently, depending on the duration of fasting in days and water temperature. This study showed the effect of different days of fasting before slaughter in rainbow trout by analyzing the intermediary metabolic enzymes in the muscle and liver. For this purpose, a non-fasting group was compared with trout that fasted for 5, 10, and 20 days (55, 107, and 200 degree days (°C d), respectively). A first phase of increased activity of enzymes involved in glycolysis was observed, increasing hexokinase enzyme activity in muscle and pyruvate kinase enzyme activity in muscle and liver. As the fasting days progressed, enzymes involved in the gluconeogenic and glycogenolytic pathways in the liver such as lactate dehydrogenase and glycogen phosphorylase increased their activity regarding the no fasted group. After 20 days of fasting (200 °C d), lipogenic and protein related enzyme activity depletion was observed, leading to significant changes in energy metabolism. Therefore, prolonged fasting with high degree days duration may compromise the energy supply for the vital development of rainbow trout.

The expanding world of metabolic enzymes moonlighting as RNA binding proteins

RNA binding proteins play key roles in many aspects of RNA metabolism and function, including splicing, translation, localization, stability and degradation. Within the past few years, proteomics studies have identified dozens of enzymes in intermediary metabolism that bind to RNA. The wide occurrence and conservation of RNA binding ability across distant branches of the evolutionary tree suggest that these moonlighting enzymes are involved in connections between intermediary metabolism and gene expression that comprise far more extensive regulatory networks than previously thought.

Metabolic and Redox Biomarkers in Skeletal Muscle Underlie Physiological Adaptations of Two Estivating Anuran Species in a South American Semi-arid Environment.

The upregulation of endogenous antioxidants (i.e., preparation for oxidative stress, POS) is part of the biochemical responses underlying the adaptation of animals to adverse environments. Despite the phylogenetic diversity of animals in which POS has been described, most studies focus on animals under controlled laboratory conditions. To address this limitation, we have recently assessed the redox metabolism in the skeletal muscle of Proceratophrys cristiceps estivating under natural settings in the Caatinga. Here, we analyzed biochemical biomarkers in the muscle of another Caatinga species, Pleurodema diplolister, during the rainy (active) and dry (estivating frogs) seasons. We aimed to determine whether P. diplolister enhances its antioxidants during estivation under field conditions and to identify any effect of species on the biochemical responses of P. diplolister and P. cristiceps associated with estivation. To do so, we measured the activities of representative enzymes of intermediary metabolism and antioxidant systems, as well as glutathione and protein carbonyl levels, in the skeletal muscle of P. diplolister. Our findings revealed the suppression of oxidative metabolism and activation of antioxidant enzymes in estivating P. diplolister compared with active specimens. No changes in oxidative damage to proteins were observed and estivating P. diplolister had lower levels of disulfide glutathione (GSSG) and disulfide-to-total glutathione ratio (GSSG/tGSH) than those observed in active individuals. When data for P. diplolister and P. cristiceps were assembled and analyzed, significant effects of species were detected on the activities of metabolic enzymes (citrate synthase, isocitric dehydrogenase, malic enzyme, and creatine kinase) and antioxidant enzymes (catalase, glutathione peroxidase and glutathione transferase), as well as on GSSG/tGSH ratio. Such effects might underlie the physiological and behavioral differences between these two species that share the same microhabitat and survival strategy (i.e., to estivate) during the dry season. Despite some peculiarities, which reflect the physiological diversity of the mechanisms associated with estivation in the Brazilian Caatinga, both P. diplolister and P. cristiceps seem to balance the suppression of oxidative pathways, the maintenance of the capacity of oxygen-independent pathways, and the activation of endogenous antioxidants to preserve muscle function and be ready to resume activity whenever the unpredictable rainy period arrives.

Bio-fertilizers and micronutrients affect the digestibility, detoxification, and intermediary metabolisms of English grain aphid, Sitobion avenae, in greenhouse

• Bio-fertilizers as key players in pest management by improving the plant tolerance. • Plant growth promoting rhizobacteria such as Biofarm showed great effect on physiology English grain aphid. • Bio-fertilizers could be a proper alternative to chemical fertilizers. • Sitobion avenae reared on wheat treated with Biofarm showed the highest activities of antioxidant enzymes. • Digestive enzymes had the highest activities in Sitobion avenae fed on Biofarm treated wheat plants. The English grain aphid, Sitobion avenae (Fabricius) (Hemiptera: Aphididae), is one of the most serious pests of cereals as the transmitter of viral diseases, mainly in wheat, Triticum aestivum . This agricultural pest is controlled with chemical insecticides, which is environmental pollutants and toxic for human. This study evaluated the potential of alternative environmentally friendly compounds to control this insect pest. The activities of digestive, antioxidants, and intermediary metabolism enzymes of S. avenae reared on wheat plants treated with bio-fertilizers (Biofarm and Probio96) and micronutrients (Librel Zinc and α-Iron) in the greenhouse were evaluated. The results reveal that α-amylase, total protease, trypsin, chymotrypsin, amino- and carboxypeptidases, alanine- and aspartate- aminotransferases, and acid phosphatase enzymes had lower activities in S. avenae reared on Biofarm treated plants compared to control. On the other hand, aphids reared on treated plants with Biofarm had the highest activities of antioxidant enzymes superoxide dismutase, catalase, peroxidase, and ascorbate oxidase, γ- glutamyl transferase, as well as lactate dehydrogenase. Moreover, the oxidized/reduced thiols ratio and malondialdehyde indicated higher activity in the aphids reared on Biofarm-treated plants than control. These results suggest that the bio-fertilizer Biofarm may compromise the physiology of S. avenae as a potential alternative toll in the integrated pest management of this aphid.

Effects of dietary arachidonic acid and docosahexanoic acid at different carbohydrates levels on gilthead sea bream growth performance and intermediary metabolism

A growth trial was performed to assess the interactive effects of high dietary levels of arachidonic acid (ARA) or docosahexaenoic acid (DHA), and carbohydrates on growth performance, feed utilization, proximate composition, plasma metabolites, and intermediary metabolism. Four isoproteic (47% crude protein) and isolipidic (18% crude lipids) diets were formulated for gilthead sea bream juveniles (47.5 g of initial mean body weight) to include low or high gelatinized starch (5 and 20% starch; LS and HS diets, respectively) and different dietary ARA/DHA content (2.3/0.3 and 0/2.6; ARA and DHA diets, respectively). Dietary ARA/DHA content did not affect growth performance or feed utilization. However, dietary starch inclusion increased feed efficiency, protein efficiency ratio, and energy retention (% intake). Dietary ARA/DHA profile did not affect the whole-body composition, but dietary starch increased whole-body dry matter, lipid, and gross energy content and decreased protein content. Low dietary ARA/DHA ratio increased plasma total protein and total lipids, triglycerides, and very-low-density lipoprotein cholesterol (VLDL) and decreased high-density lipoprotein cholesterol (HDL) and low-density lipoprotein cholesterol (LDL), independently of the dietary starch level. On the other hand, in LS diets, total cholesterol levels were lower in fish fed the diet rich in DHA than those fed with ARA. HS diets increased glucose, total protein and lipids, triglycerides, and VLDL plasmatic values, and decreased HDL. HS diets increased the carbohydrates intermediary metabolism and lipogenic enzymes. ARA and HS increased fatty acid desaturase 2 (FADS2) and decreased elongation of very long-chain fatty acid 5 protein (ELOVL5) in the liver, and only HS decreased ELOVL5 in the intestine. The muscle fatty acid content followed the dietary fatty acid profile, but ARA, EPA, and DHA content were increased in LS diets. In conclusion, few interactions between ARA or DHA and dietary digestible carbohydrates were found. The results indicate that at least in the presence of high ARA levels the n-3 LC-PUFA requirements were fulfilled with 0.5% EPA + DHA and gilthead sea bream tolerates well dietary inclusion of 20% starch.

Effects of fish oil substitution by hazelnut oil on growth performance, whole‐body fatty acid composition and enzymes of intermediary metabolism of juvenile meagre ( Argyrosomus regius Asso, 1801)

The need for new alternative oil sources in the ever-increasing aquaculture of carnivorous species is imperative. We substituted fish oil (FO) with hazelnut oil (HO) in meagre diet at 20, 40, 60, 80 and 100%. Triplicate groups of 40 fish/tank juvenile meagre (ca 15 g) were used. For the reduction of FO level in meagre diet, a 40% substitution by HO is attainable without affecting growth performance. However, higher substitutions appear to have a negative effect on growth performance and feed efficiency, although daily feed intake seems to remain unaffected by the reduction in FO. No effects on whole-body protein and lipid concentration were observed for fish fed the experimental diets. Whole-body fatty acid composition reflected the dietary fatty acid composition in all dietary groups. Diets with higher than 40% levels of FO substitution significantly reduce highly unsaturated ω-3 fatty acids in the fish. Although the metabolic relationship between carbohydrate and fatty acid exploitation is extremely versatile, and thus it is difficult to reach a safe conclusion, it seems that FO substitution by HO activates fish carbohydrate, rather than fatty acids, exploitation machinery. These results support the use of HO in meagre diets up to 40% FO substitution with a future thought for more efficient use of 30% FO substitution by HO.

The expanding world of metabolic enzymes moonlighting as RNA binding proteins.

RNA binding proteins play key roles in many aspects of RNA metabolism and function, including splicing, transport, translation, localization, stability and degradation. Within the past few years, proteomics studies have identified dozens of enzymes in intermediary metabolism that bind to RNA. The wide occurrence and conservation of RNA binding ability across distant branches of the evolutionary tree suggest that these moonlighting enzymes are involved in connections between intermediary metabolism and gene expression that comprise far more extensive regulatory networks than previously thought. There are many outstanding questions about the molecular structures and mechanisms involved, the effects of these interactions on enzyme and RNA functions, and the factors that regulate the interactions. The effects on RNA function are likely to be wider than regulation of translation, and some enzyme-RNA interactions have been found to regulate the enzyme's catalytic activity. Several enzyme-RNA interactions have been shown to be affected by cellular factors that change under different intracellular and environmental conditions, including concentrations of substrates and cofactors. Understanding the molecular mechanisms involved in the interactions between the enzymes and RNA, the factors involved in regulation, and the effects of the enzyme-RNA interactions on both the enzyme and RNA functions will lead to a better understanding of the role of the many newly identified enzyme-RNA interactions in connecting intermediary metabolism and gene expression.

The relation between acute changes in the systemic inflammatory response and circulating thiamine and magnesium concentrations after elective knee arthroplasty

Thiamine diphosphate (TDP) and magnesium are co-factors for key enzymes in human intermediary metabolism. However, their role in the systemic inflammatory response (SIR) is not clear. Therefore, the aim of the present study was to examine the relation between acute changes in the SIR and thiamine and magnesium dependent enzyme activity in patients undergoing elective knee arthroplasty (a standard reproducible surgical injury in apparently healthy individuals). Patients (n = 35) who underwent elective total knee arthroplasty had venous blood samples collected pre- and post-operatively for 3 days, for measurement of whole blood TDP, serum and erythrocyte magnesium, erythrocyte transketolase activity (ETKA), lactate dehydrogenase (LDH), glucose and lactate concentrations. Pre-operatively, TDP concentrations, erythrocyte magnesium concentrations, ETKA and plasma glucose were within normal limits for all patients. In contrast, 5 patients (14%) had low serum magnesium concentrations (< 0.75 mmol/L). On post-operative day1, both TDP concentrations (p < 0.001) and basal ETKA (p < 0.05) increased and serum magnesium concentrations decreased (p < 0.001). Erythrocyte magnesium concentrations correlated with serum magnesium concentrations (rs = 0.338, p < 0.05) and remained constant during SIR. Post-operatively 14 patients (40%) had low serum magnesium concentrations. On day1 serum magnesium concentrations were directly associated with LDH (p < 0.05), WCC (p < 0.05) and neutrophils (p < 0.01). Whole blood TDP and basal ETKA increased while serum magnesium concentrations decreased, indicating increased requirement for thiamine and magnesium dependent enzyme activity during SIR. Therefore, thiamine and magnesium represent potentially modifiable therapeutic targets that may modulate the host inflammatory response. Erythrocyte magnesium concentrations are likely to be reliable measures of status, whereas serum magnesium concentrations and whole blood TDP may not.ClinicalTrials.gov: NCT03554668.

Effect of dietary carbohydrates on growth performance, feed efficiency and glucose metabolism in common snook (Centropomus undecimalis) and yellowtail snapper (Ocyurus chrysurus) juveniles

In recent years, interest in commercial farming of the common snook Centropomus undecimalis and yellowtail snapper Ocyurus chrysurus has been increasing in the Atlantic West; however, these species are carnivorous with a high protein requirement in the diet. A 75-day feeding trial was conducted to evaluate the effect of dietary carbohydrates on growth performance, feed efficiency, glycemic response, digestive and key liver enzymes of intermediary metabolism of C. undecimalis and O. chrysurus. Two diets were formulated to contain 51.6% protein, 7.9% lipid and 20% corn starch (High digestive carbohydrates diet, HC) or 20% wheat bran (Control diet, C). Growth performance was not affected by dietary carbohydrates in both species. The feed efficiency (FE) and protein efficiency ratio (PER) improved in C. undecimalis fed the HC diet; however, for O. chrysurus, FE and PER were not affected by the HC diet. The hepatic glycogen and whole-body lipid content increased in C. undecimalis fed the HC diet, but this did not occur in O. chrysurus. Intestinal amylase activity increased in both species with the HC diet. Blood glucose peaked in C. undecimalis six hours after being fed with the HC diet (7.8 mmol L−1), whereas the glucose peak in O. chrysurus occurred until nine hours (14.1 mmol L−1). Hepatic glucokinase (GK) activity increased with the HC diet in both fish species. However, at the molecular level, GK mRNA expression was higher in C. undecimalis fed the HC diet, but for O. chrysurus, GK mRNA expression did not differ between diets. Glucose-6-phosphate dehydrogenase (G6PDH) and 6-phosphogluconate dehydrogenase (6PGDH) activities increased only in C. undecimalis fed the HC diet. Pyruvate kinase (PK) increased and fructose-1, 6-bisphosphatase (FBPase) decreased in both species fed the HC diet. Alanine aminotransferase (ALT) activity was unaffected by experimental diets, but O. chrysurus showed higher activity than C. undecimalis. These results suggest that both fish species are able to adapt to a high-carbohydrate diet by reorganization carbohydrate metabolism. However, C. undecimalis showed a greater capacity to utilize and store carbohydrates than O. chrysurus.

Advances in understanding the impacts of global warming on marine fishes farmed offshore: Sparus aurata as a case study.

Monitoring variations in proteins involved in metabolic processes, oxidative stress responses, cell signalling and protein homeostasis is a powerful tool for developing hypotheses of how environmental variations affect marine organisms' physiology and biology. According to the oxygen- and capacity-limited thermal tolerance hypothesis, thermal acclimation mechanisms such as adjusting the activities of enzymes of intermediary metabolism and of antioxidant defence mechanisms, inducing heat shock proteins (Hsps) or activating mitogen-activated protein kinases may all shift tolerance windows. Few studies have, however, investigated the molecular, biochemical and organismal responses by fishes to seasonal temperature variations in the field to link these to laboratory findings. Investigation of the impacts of global warming on fishes farmed offsore, in the open sea, can provide a stepping stone towards understanding effects on wild populations because they experience similar environmental fluctuations. Over the last 30 years, farming of the gilthead sea bream Sparus aurata (Linnaeus 1758) has become widespread along the Mediterranean coastline, rendering this species a useful case study. Based on available information, the prevailing seasonal temperature variations expose the species to the upper and lower limits of its thermal range. Evidence for this includes oxygen restriction, reduced feeding, reduced responsiveness to environmental stimuli, plus a range of molecular and biochemical indicators that change across the thermal range. Additionally, close relationships between biochemical pathways and seasonal patterns of metabolism indicate a connection between energy demand and metabolic processes on the one hand, and cellular stress responses such as oxidative stress, inflammation and autophagy on the other. Understanding physiological responses to temperature fluctuations in fishes farmed offshore can provide crucial background information for the conservation and successful management of aquaculture resources in the face of global change.

Seasonal metabolic and oxidative stress responses of commercially important invertebrate species—correlation with their habitat

Habitat conditions play a crucial role in food acquisition and the energetic and physiological performance of marine organisms during seasonal changes. However, across a wide distribution, populations of the same species might face physiological constraints driven by the oceanographic and climatological characteristics of their habitats. In the context of climate change, biochemical and metabolic data may be important in identifying marine areas in which inhabiting organisms are more or less physiologically constrained. As a first step in identifying such marine areas on the Greek coast, we studied the seasonal metabolic and antioxidant responses of blue crab Callinectes sapidus, cuttlefish Sepia officinalis, sea cucumber Holothuria tubulosa and clam Venus verrucosa, collected from 3 different Greek gulfs: Thermaikos, Pagasitikos and Vistonikos. Seasonal analysis of metabolic responses was based on the activity of the following intermediary metabolic enzymes: lactate dehydrogenase (L-LDH), octopine dehydrogenase (ODH), β-hydroxyacyl-CoA dehydrogenase (HOAD) and citrate synthase (CS). Antioxidant responses were based on the activities of the following enzymes: superoxide dismutase (SOD), glutathione reductase (GR) and catalase, and on lipid peroxidation estimation. The blue crab and clam exhibited the most significant seasonal changes compared to the sea cucumber and cuttlefish, which exhibited no changes. The intermediary metabolism enzymatic activity of blue crab and clam decreased and antioxidant enzymatic activity increased during summer. Higher activity levels for all examined species were observed in Pagasitikos and lower levels in Vistonikos Gulf, indicating corresponding oxidative stress. These results are correlated with the spatial oceanographic conditions of the habitats and are discussed based on future projections of global warming in the Mediterranean Sea.

Correlation between intermediary metabolism, Hsp gene expression, and oxidative stress-related proteins in long-term thermal-stressed Mytilus galloprovincialis.

Long-term exposure of Mytilus galloprovincialis to temperatures beyond 26°C triggers mussel mortality. The present study aimed to integratively illustrate the correlation between intermediary metabolism, hsp gene expression, and oxidative stress-related proteins in long-term thermally stressed Mytilus galloprovincialis and whether they are affected by thermal stress magnitude and duration. We accordingly evaluated the gene expression profiles, in the posterior adductor muscle (PAM) and the mantle, concerning heat shock protein 70 and 90 (hsp70 and hsp90), and the antioxidant defense indicators Mn-SOD, Cu/Zn-SOD, catalase, glutathione S-transferase, and the metallothioneins mt-10 and mt-20. Moreover, we determined antioxidant enzyme activities, oxidative stress through lipid peroxidation, and activities of intermediary metabolism enzymes. The pattern of changes in relative mRNA expression levels indicate that mussels are able to sense thermal stress even when exposed to 22°C and before mussel mortality is initiated. Data indicate a close correlation between the magnitude and duration of thermal stress with lipid peroxidation levels and changes in the activity of antioxidant enzymes and the enzymes of intermediary metabolism. The gene expression and increase in the activities of antioxidant enzymes support a scenario, according to which exposure to 24°C might trigger reactive oxygen species (ROS) production, which is closely correlated with anaerobic metabolism under hypometabolic conditions. Increase and maintenance of oxidative stress in conjunction with energy balance disturbance seem to trigger mussel mortality after long-term exposure at temperatures beyond 26°C. Eventually, in the context of preparation for oxidative stress, certain hypotheses and models are suggested, integrating the several steps of cellular stress response.

Inborn errors of metabolite repair.

It is traditionally assumed that enzymes of intermediary metabolism are extremely specific and that this is sufficient to prevent the production of useless and/or toxic side‐products. Recent work indicates that this statement is not entirely correct. In reality, enzymes are not strictly specific, they often display weak side activities on intracellular metabolites (substrate promiscuity) that resemble their physiological substrate or slowly catalyse abnormal reactions on their physiological substrate (catalytic promiscuity). They thereby produce non‐classical metabolites that are not efficiently metabolised by conventional enzymes. In an increasing number of cases, metabolite repair enzymes are being discovered that serve to eliminate these non‐classical metabolites and prevent their accumulation. Metabolite repair enzymes also eliminate non‐classical metabolites that are formed through spontaneous (ie, not enzyme‐catalysed) reactions. Importantly, genetic deficiencies in several metabolite repair enzymes lead to ‘inborn errors of metabolite repair’, such as L‐2‐hydroxyglutaric aciduria, D‐2‐hydroxyglutaric aciduria, ‘ubiquitous glucose‐6‐phosphatase’ (G6PC3) deficiency, the neutropenia present in Glycogen Storage Disease type Ib or defects in the enzymes that repair the hydrated forms of NADH or NADPH. Metabolite repair defects may be difficult to identify as such, because the mutated enzymes are non‐classical enzymes that act on non‐classical metabolites, which in some cases accumulate only inside the cells, and at rather low, yet toxic, concentrations. It is therefore likely that many additional metabolite repair enzymes remain to be discovered and that many diseases of metabolite repair still await elucidation.

Alterations of Mitochondria and Related Metabolic Pathways in Leukemia: A Narrative Review.

Dysregulation of mitochondrial function often precedes malignant transformation of hematopoietic stem cells (HSCs). Mitochondria have a direct role in the maintenance of HSC functions. For example, D-2-hydroxyglutarate, generated due to the activity of mutated mitochondrial isocitrate dehydrogenase (IDH), has been implicated in the pathogenesis of leukemia. Furthermore, disturbances in the fatty acid breakdown and pyruvate oxidation are often seen in leukemic cells. These and other abnormalities expedite leukemogenesis and chemoresistance of leukemic cells. However, it needs to be elucidated whether these aberrations are the result or cause of leukemogenesis. Accordingly, for this review, a search was carried out in PubMed and Google Scholar databases until June 2019 to assess the relationship between metabolic pathways in altered mitochondria and leukemia development. In the present review, an overview of mitochondria-related mechanisms and their abnormalities in leukemia is presented, with mitochondrial pathways and factors, such as mitophagy, intermediary metabolism enzymes, oncometabolites and reactive oxygen species' generation, discussed as potential diagnostic and therapeutic targets in leukemia.

The moonlighting RNA-binding activity of cytosolic serine hydroxymethyltransferase contributes to control compartmentalization of serine metabolism.

Enzymes of intermediary metabolism are often reported to have moonlighting functions as RNA-binding proteins and have regulatory roles beyond their primary activities. Human serine hydroxymethyltransferase (SHMT) is essential for the one-carbon metabolism, which sustains growth and proliferation in normal and tumour cells. Here, we characterize the RNA-binding function of cytosolic SHMT (SHMT1) in vitro and using cancer cell models. We show that SHMT1 controls the expression of its mitochondrial counterpart (SHMT2) by binding to the 5′untranslated region of the SHMT2 transcript (UTR2). Importantly, binding to RNA is modulated by metabolites in vitro and the formation of the SHMT1–UTR2 complex inhibits the serine cleavage activity of the SHMT1, without affecting the reverse reaction. Transfection of UTR2 in cancer cells controls SHMT1 activity and reduces cell viability. We propose a novel mechanism of SHMT regulation, which interconnects RNA and metabolites levels to control the cross-talk between cytosolic and mitochondrial compartments of serine metabolism.

Synergistic inactivation and mechanism of thermal and ultrasound treatments against Bacillus subtilis spores

Some Bacillus species are causative agents of food spoilage and a wide array of diseases. Due to their ability to form highly heat-resistant spores, it is of great interest to develop more effective inactivation strategies whereby these spores could be inactivated. Therefore, this work assessed inactivation of thermal and ultrasound treatments against Bacillus subtilis spores. The study further investigated the thermosonication (thermal and ultrasound, TS) -induced inactivation to the spores through a combination of morphology observation and internal factor analyses. The results of TS indicated that the TS combination synergistically inactivated spores by the maximum log reduction of 2.43 ± 0.08 at 80 °C and 20 W/ml and caused severe cell damage. The visual images revealed that the destructive mode of action of TS had multitarget sites, including coat, cortex, and inner membrane. Three distinct sub-populations were detected by Flow cytometry (FCM), and an unknown step with some physical compromise of the spore's inner membrane and partially hydrolyzed cortex involving the three steps model of inactivation was suggested. The combination of DPA (pyridine-2,6 dicarboxylic acid) content and the relative viabilities of the fractions suggested that during the TS treatment DPA release took place largely after spore death. The dead spores that retained DPA germinated relatively normally, but outgrow poorly, indicating that some key enzymes of intermediary metabolism has been damaged by TS treatment. Such understanding of the lethal action of TS may lead to the development of novel strategies involving spore destruction.

O-GlcNAc in cancer: An Oncometabolism-fueled vicious cycle.

Cancer cells exhibit unregulated growth, altered metabolism, enhanced metastatic potential and altered cell surface glycans. Fueled by oncometabolism and elevated uptake of glucose and glutamine, the hexosamine biosynthetic pathway (HBP) sustains glycosylation in the endomembrane system. In addition, the elevated pools of UDP-GlcNAc drives the O-GlcNAc modification of key targets in the cytoplasm, nucleus and mitochondrion. These targets include transcription factors, kinases, key cytoplasmic enzymes of intermediary metabolism, and electron transport chain complexes. O-GlcNAcylation can thereby alter epigenetics, transcription, signaling, proteostasis, and bioenergetics, key 'hallmarks of cancer'. In this review, we summarize accumulating evidence that many cancer hallmarks are linked to dysregulation of O-GlcNAc cycling on cancer-relevant targets. We argue that onconutrient and oncometabolite-fueled elevation increases HBP flux and triggers O-GlcNAcylation of key regulatory enzymes in glycolysis, Kreb's cycle, pentose-phosphate pathway, and the HBP itself. The resulting rerouting of glucose metabolites leads to elevated O-GlcNAcylation of oncogenes and tumor suppressors further escalating elevation in HBP flux creating a 'vicious cycle'. Downstream, elevated O-GlcNAcylation alters DNA repair and cellular stress pathways which influence oncogenesis. The elevated steady-state levels of O-GlcNAcylated targets found in many cancers may also provide these cells with a selective advantage for sustained growth, enhanced metastatic potential, and immune evasion in the tumor microenvironment.