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The African clawed frog, Xenopus laevis , can withstand extremely arid conditions through aestivation, resulting in dehydration and urea accumulation. Aestivating X. laevis reduce their metabolic rate, and rely on anaerobic glycolysis to meet reduced ATP demands. The present study investigated how severe dehydration affected the transcript levels, kinetic profile, and phosphorylation state of the key glycolytic enzyme pyruvate kinase (PK) in the liver and skeletal muscle of X. laevis . Compared to control frogs, severely dehydrated frogs showed an increase in the transcript abundance of both liver and muscle isoforms of PK. While the kinetics of muscle PK did not differ between dehydrated and control frogs, PK from the liver of dehydrated frogs had a lower K m for phosphoenolpyruvate (PEP) (38%), a lower K a for fructose-1,6-bisphosphate (F1,6P 2 ) (32%), and a greater activation of PK via F1,6P 2 (1.56-fold). PK from dehydrated frogs also had a lower phosphorylation-state (25%) in comparison to the enzyme from control frogs in the liver. Experimental manipulation of the phosphorylation-state of liver PK taken from control frogs by endogenous protein phosphatases resulted in decreased phosphorylation, and a similar kinetic profile as seen in dehydrated frogs. The physiological consequence of dehydration-induced PK modification appears to adjust PK function to remain active during a metabolically depressed state. This study provides evidence for the maintenance of PK activity through elevated mRNA levels and a dephosphorylation event which activates frog liver PK in the dehydrated state in order to facilitate the production of ATP via anaerobic glycolysis. [ABSTRACT FROM AUTHOR]

After experiencing anaerobic environments, Aphelenchoides besseyi will enter a state of suspended animation known as anoxybiosis, during which it may use trehalose as an energy supply to survive. To explore the function of trehalose metabolism, two trehalose-6- phosphate synthase (TPS) genes (Ab-tps1 and Ab-tps2) encoding enzymes catalysing trehalose synthesis, and three trehalase (TRE) genes (Ab-ntre1, Ab-ntre2 and Ab-atre) encoding enzymes catalysing the hydrolysis of trehalose, were identified and investigated. Ab-tps1 and Ab-tps2 were active during certain periods of anoxybiosis for A. besseyi, and Ab-tps2, Ab-ntre1, Abntre2 and Ab-atre were active during certain periods of recovery. The results of RNA interference experiments suggested that TRE genes regulated each other and both TPS genes, while a single TPS gene only regulated the other TPS gene. However, two TPS genes together could regulate TRE genes, which indicated a feedback mechanism between these genes. All these genes also positively regulated the survival and resumption of active metabolism of the nematode. Genes functioning at re-aeration have a greater impact on nematode survival, suggesting that these genes could play roles in anoxybiosis regulation, but may function within restricted time frames. Changes in trehalose levels matched changes in TRE activity during the anoxybiosis--re-aeration process, suggesting that trehalose may act as an energy supply source. The observation of up-regulation of TPS genes during anoxybiosis suggested a possible signal role of trehalose. Trehalose metabolism genes could also work together to control trehalose levels at a certain level when the nematode is under anaerobic conditions. [ABSTRACT FROM AUTHOR]

Running events range from 60-m sprints to ultra-marathons covering 100 miles or more, which presents an interesting diversity in terms of the parameters for successful performance. Here, we review the physiological and biomechanical variations underlying elite human running performance in sprint to ultramarathon distances. Maximal running speeds observed in sprint disciplines are achieved by high vertical ground reaction forces applied over short contact times. To create this high force output, sprint events rely heavily on anaerobic metabolism, as well as a high number and large cross-sectional area of type II fibers in the leg muscles. Middle distance running performance is characterized by intermediates of biomechanical and physiological parameters, with the possibility of unique combinations of each leading to high-level performance. The relatively fast velocities in mid-distance events require a high mechanical power output, though ground reaction forces are less than in sprinting. Elite mid-distance runners exhibit local muscle adaptations that, along with a large anaerobic capacity, provide the ability to generate a high power output. Aerobic capacity starts to become an important aspect of performance in middle distance events, especially as distance increases. In distance running events, V̇O2 is an important determinant of performance, but is relatively homogeneous in elite runners. V̇O2 and velocity at lactate threshold have been shown to be superior predictors of elite distance running performance. Ultramarathons are relatively new running events, as such, less is known about physiological and biomechanical parameters that underlie ultra-marathon performance. However, it is clear that performance in these events is related to aerobic capacity, fuel utilization, and fatigue resistance. [ABSTRACT FROM AUTHOR]

Escherichia coli open reading frames ydiO and ydiQRST were identified as genes encoding components of the acyl-CoA dehydrogenase complex of anaerobic fatty acid β-oxidation. Individual or concomitant inactivation of fadE gene, encoding known aerobic acyl-CoA dehydrogenase, and ydiO and/or ydiQRST genes did not affect cellular growth on glucose as a sole carbon source. Aerobic growth on sodium oleate was observed only for the cells with intact fadE gene. With an alternative electron acceptor, the cells possessing intact fadE gene demonstrated anaerobic growth on sodium oleate irrespective of the presence or absence of ydiO and ydiQRST genes. For the fadE-deficient mutants, anaerobic growth on sodium oleate was observed only for cells with intact ydiO and ydiQRST genes, while the fadE/ ydiO and fadE/ ydiQRST mutants failed to grow under the similar conditions. [ABSTRACT FROM AUTHOR]

Highlights: [•] Cu exposure affects the level of free energy in clam hemolymph. [•] Contents of major energy stores in tissues were not affected by Cu exposure. [•] Cu exposure increases clam reliance upon anaerobic energy production. [Copyright &y& Elsevier]

Background: Hepatic steatosis is a major risk factor for graft failure in liver transplantation. Hepatic steatosis shows a greater negative influence on graft function following prolonged cold ischaemia. As the impact of steatosis on hepatocyte metabolism during extended cold ischaemia is not well-described, we compared markers of metabolic capacity and mitochondrial function in steatotic and lean livers following clinically relevant durations of cold preservation. Methods: Livers from 10-week old leptin-deficient obese (ob/ob, n = 9) and lean C57 mice (n = 9) were preserved in ice-cold University of Wisconsin solution. Liver mitochondrial function was then assessed using high resolution respirometry after 1.5, 3, 5, 8, 12, 16 and 24 hours of storage. Metabolic marker enzymes for anaerobiosis and mitochondrial mass were also measured in conjunction with non-bicarbonate tissue pH buffering capacity. Results: Ob/ob and lean mice livers showed severe (>60%) macrovesicular and mild (<30%) microvesicular steatosis on Oil Red O staining, respectively. Ob/ob livers had lower baseline enzymatic complex I activity but similar adenosine triphosphate (ATP) levels compared to lean livers. During cold storage, the respiratory control ratio and complex I-fueled phosphorylation deteriorated approximately twice as fast in ob/ob livers compared to lean livers. Ob/ob livers also demonstrated decreased ATP production capacities at all time-points analyzed compared to lean livers. Ob/ob liver baseline lactate dehydrogenase activities and intrinsic non-bicarbonate buffering capacities were depressed by 60% and 40%, respectively compared to lean livers. Conclusions: Steatotic livers have impaired baseline aerobic and anaerobic capacities compared to lean livers, and mitochondrial function indices decrease particularly from after 5 hours of cold preservation. These data provide a mechanistic basis for the clinical recommendation of shorter cold storage durations in steatotic donor livers. [ABSTRACT FROM AUTHOR]

Cellular metabolism continuously processes an enormous range of external compounds into endogenous metabolites and is as such a key element in human physiology. The multifaceted physiological role of the metabolic network fulfilling the catalytic conversions can only be fully understood from a whole-body perspective where the causal interplay of the metabolic states of individual cells, the surrounding tissue and the whole organism are simultaneously considered. We here present an approach relying on dynamic flux balance analysis that allows the integration of metabolic networks at the cellular scale into standardized physiologically-based pharmacokinetic models at the whole-body level. To evaluate our approach we integrated a genome-scale network reconstruction of a human hepatocyte into the liver tissue of a physiologically-based pharmacokinetic model of a human adult. The resulting multiscale model was used to investigate hyperuricemia therapy, ammonia detoxification and paracetamol-induced toxication at a systems level. The specific models simultaneously integrate multiple layers of biological organization and offer mechanistic insights into pathology and medication. The approach presented may in future support a mechanistic understanding in diagnostics and drug development. [ABSTRACT FROM AUTHOR]

Dynamic flux balance analysis was utilized to simulate the metabolic behaviour of initially fully respirative and respirofermentative steady-state cultures of Saccharomyces cerevisiae during sudden oxygen depletion. The hybrid model for the dynamic flux balance analysis included a stoichiometric genome-scale metabolic model as a static part and dynamic equations for the uptake of glucose and the cessation of respirative metabolism. The yeast consensus genome-scale metabolic model [Herrgård MJ et al. (2008) Nat Biotechnol 26, 1155-1160; Dobson PD et al. (2010) BMC Syst Biol 4, 145] was refined with respect to oxygen-dependent energy metabolism and further modified to reflect S. cerevisiae anabolism in the absence of oxygen. Dynamic flux balance analysis captured well the essential features of the dynamic metabolic behaviour of S. cerevisiae during adaptation to anaerobiosis. Modelling and simulation enabled the identification of short time-scale flux distribution dynamics under the transition to anaerobic metabolism, during which the specific growth rate was reduced, as well as longer time-scale process dynamics when the specific growth rate recovered. Expression of the metabolic genes was set into the context of the identified dynamics. Metabolic gene expression responses associated with the specific growth rate and with the cessation of respirative metabolism were distinguished. [ABSTRACT FROM AUTHOR]

Abstract: We describe an efficient and scalable procedure for the chemical synthesis of nucleoside 5′-phosphosulfates (NPS) from nucleoside 5′-phosphorimidazolides and sulfate bis(tributylammonium) salt. Using this method we obtained various NPS with yields ranging from 70–90%, including adenosine 5′-phosphosulfate (APS) and 2′,3′-cyclic precursor of 3′-phosphoadenosine 5′-phosphosulfate (PAPS), which are the key intermediates in the assimilation and metabolism of sulfur in all living organisms. [Copyright &y& Elsevier]

Background: Trichostatin A (TSA) is one of the most potent histone deacetylase inhibitors (HDACi) in vitro but it lacks biological activity in vivo when injected intravenously owing to its fast metabolism. Materials and methods: TSA was incorporated into Stealth® liposomes (TSA-lipo) at a high loading and its anticancer activity was evaluated in several types of breast cancer cells and xenografts. Results: In estrogen receptor α (ERα)-positive MCF-7 and T47-D cells, TSA induced a long-term degradation of cyclin A and a proteasome-dependent loss of ERα and cyclin D1, allowed derepression of p21WAF1/CIP1, HDAC1 and RhoB GTPase, concomitantly with blockade in G2/M of the cell cycle and apoptosis induction. In MDA-MB-231 (MDA) and SKBr-3 cells, TSA increased ERα mRNA and p21WAF1/CIP1 protein expression, but decreased cyclin A with a G2/M blockade and cleavage of polyADP-ribose polymerase (PARP). No significant restoration of any ER protein was noticed in any cells. TSA-lipo markedly inhibited tumor growth in MCF-7 and MDA cells xenografts following intravenous injection. Their anticancer effects were characterized by inhibition of Ki-67 labeling, the inhibition of tumor vasculature and an increase of p21WAF1/CIP1 in both tumors. In MCF-7 cell tumors, enhanced RhoB accumulation in the cytoplasm of epithelial cells was noticed, inversely to ERα that was strongly decreased. Conclusion: Such anticancer activity of TSA-lipo is exp-lained by the protection provided by HDACi encapsulation and by the strong tumor accumulation of the nanocarriers as revealed by fluorescence confocal microscopy experi-ments. Together with its lack of toxicity, the enhanced stability of TSA-lipo in vivo justifies its development for therapeutic use in the treatment estradiol-dependent and -independent breast cancers. [ABSTRACT FROM AUTHOR]

Abstract: Genome-based Flux Balance Analysis (FBA) and steady-state isotopic-labeling-based Metabolic Flux Analysis (MFA) are complimentary approaches to predicting and measuring the operation and regulation of metabolic networks. Here, genome-derived models of Escherichia coli (E. coli) metabolism were used for FBA and 13C-MFA analyses of aerobic and anaerobic growths of wild-type E. coli (K-12 MG1655) cells. Validated MFA flux maps reveal that the fraction of maintenance ATP consumption in total ATP production is about 14% higher under anaerobic (51.1%) than aerobic conditions (37.2%). FBA revealed that an increased ATP utilization is consumed by ATP synthase to secrete protons from fermentation. The TCA cycle is shown to be incomplete in aerobically growing cells and submaximal growth is due to limited oxidative phosphorylation. An FBA was successful in predicting product secretion rates in aerobic culture if both glucose and oxygen uptake measurement were constrained, but the most-frequently predicted values of internal fluxes yielded from sampling the feasible space differ substantially from MFA-derived fluxes. [ABSTRACT FROM AUTHOR]

Abstract: Sulfur deprivation, which is considered as an efficient way to trigger long-term hydrogen photoproduction in unicellular green algae has two major effects: a decrease in PSII which allows anaerobiosis to be reached and carbohydrate (starch) storage. Starch metabolism has been proposed as one of the major factors of hydrogen production, particularly during the PSII-independent (or indirect) pathway. While starch biosynthesis has been characterized in the green alga Chlamydomonas reinhardtii, little remains known concerning starch degradation. In order to gain a better understanding of starch catabolism pathways and identify those steps likely to limit the starch-dependent hydrogen production, we have designed a genetic screening procedure aimed at isolating mutants of the green alga C. reinhardtii affected in starch mobilization. Using two different screening protocols, the first one based on aerobic starch degradation in the dark and the second one on anaerobic starch degradation in the light, eighteen mutants were isolated among a library of 15,000 insertion mutants, eight (std1-8) with the first screen and ten (sda1-10) with the second. Most of the mutant strains isolated in this study showed a reduction or a delay in the PSII-independent hydrogen production. Further characterization of these mutants should allow the identification of molecular determinants of starch-dependent hydrogen production and supply targets for future biotechnological improvements. [ABSTRACT FROM AUTHOR]

The article presents a study which evaluates the oxidative stress responses of Streptococcus pneumoniae and define a role for Rgg in the pneumococcus. It determines the oxidative adaptation of S. pneumoniae through the global gene profile of the microorganism in aerobiosis and anaerobiosis while relation of Rgg in pneumococcal oxidative adaptation was found by constructing an isogenic mutant. The results indicate that the S. pneumonia oxidative response is not limited to gene expression.

The article reports that Vitamin B1 is in its active form thiamine pyrophosphate (TPP), an essential cofactor for several key enzymes in the carbohydrate metabolism. It is mentioned that mammals need to salvage crucial nutrient from their diet in order to complement the deficiency of de novo synthesis. In the human pathogenic bacterium Staphylococcus aureus, two operons were identified which are involved in vitamin B1 metabolism. It is mentioned that the kinetic properties of the enzymes as well as the binding of TPP to the in vitro transcribed RNA of the proposed operons suggest that the vitamin B1 homeostasis in S. aureus is strongly regulated at transcriptional as well as enzymatic levels.

Abstract: Microbial fermentation is a potentially important member of a diverse portfolio of methods available for renewable production of hydrogen using biomass as a substrate. A major factor currently limiting commercial viability of fermentative hydrogen production is poor stoichiometric yield per mole of sugar and end-product feedback inhibition. Although several approaches have been tried to enhance microbial hydrogen productivity, genetic engineering technologies for most promising microorganisms are either unavailable or severely limited. Further efforts to overcome existing issues will need to rely on the ability to analyze, predict and engineer microbial metabolism in native H2-producing strains as well as genetically engineerable strains with constructed H2-metabolism. A shift in the type of biomass substrate from starch-based food crops to ligno-cellulosic crops and wastes that are economically and environmentally less costly to produce, yet more difficult to chemically and biologically process, presents technical challenges that are shared by all emerging biofuel technologies. A brief overview of the current status of fermentative H2-production, including a discussion of directly and indirectly related emerging technologies, is presented. [Copyright &y& Elsevier]

We report the synthesis and X-ray crystal structures of a series of pyridyl ureas of the type currently topical in anion binding and supramolecular gelation applications, along with their anion-binding ability in solution. The structures of the simple pyridyl ureas are dominated by urea···N(pyridyl) hydrogen bonding, because of steric congestion of the urea carbonyl by intramolecular CH···O interations. However, introducing a further competing synthon in the form of alkenic or π-stacking interactions causes a gradual changeover, through a number of interesting intermediate hydrogen bonding motifs, to the urea α-tape arrangement. [ABSTRACT FROM AUTHOR]

Heterotermes tenuis is a native termite of large negative impact on the Brazilian economy. Many studies have focused on optimizing the baiting method for termite control by improving its use and its efficacy. In order to maximize termite bait consumption, this study aimed to select nutrient solutions which are able to enhance termite feeding. The effects of some sugars and urea on feeding preference of the subterranean termite H. tenuis were determined by double choice feeding tests, and the consumption was evaluated by variation in dry mass of filter paper after 28 days of termite feeding. Most of the solutions tested did not significantly influence feeding of H. tenuis. Termites fed preferentially on filter paper treated with 0.03 g/ml trehalose and 0.015 g/ml urea solutions. The data indicate that trehalose and urea solutions are phagostimulants to H. tenuis, and their future use in bait matrices may increase consumption of baits and improve this control technique. [ABSTRACT FROM AUTHOR]

Abstract: In fungi, the velvet gene, or veA, is involved in the regulation of diverse cellular processes, including control of asexual and sexual development as well as secondary metabolism. This global regulator is conserved in numerous fungal species. Interestingly, in Aspergilli, where most of the studies on veA have been carried out, this gene has been described to mediate development in response to light. In recent years the knowledge of this important regulatory system has expanded through the use of Aspergillus nidulans as a model organism, and through the study of veA orthologs across fungal genera. This review includes information on the current understanding of veA function and its mechanism of action. The fact that veA has only been found in fungi, together with advances in the elucidation of the veA mechanism, might be useful in designing future control strategies to decrease the detrimental effects of fungi while enhancing those qualities that are beneficial. [Copyright &y& Elsevier]

Abstract: The posterior cingulate cortex (PCC) is the brain region displaying the earliest sign of energy hypometabolism in patients with amnestic mild cognitive impairment (MCI) who develop Alzheimer’s disease (AD). In particular, the activity of the mitochondrial respiratory enzyme cytochrome oxidase (C.O.) is selectively inhibited within the PCC in AD. The present study is the first experimental analysis designed to model in animals the localized cortical C.O. inhibition found as the earliest metabolic sign of early-stage AD in human neuroimaging studies. Rats were used to model local inhibition of C.O. by direct injection of the C.O. inhibitor sodium azide into the PCC. Learning and memory were examined in a spatial holeboard task and brains were analyzed using quantitative histochemical, morphological and biochemical techniques. Behavioral results showed that sodium azide-treated rats were impaired in their memory of the baited pattern in probe trials as compared to their training scores before treatment, without non-specific behavioral differences. Brain analyses showed that C.O. inhibition was specific to the PCC, and sodium azide increased lipid peroxidation, gliosis and neuron loss, and lead to a network functional disconnection between the PCC and interconnected hippocampal regions. It was concluded that impaired memory by local C.O. inhibition in the PCC may serve to model in animals a metabolic lesion similar to that found in patients with amnestic MCI and early-stage AD. This model may be useful as an in vivo testing platform to investigate neuroprotective strategies to prevent or reduce the amnestic effects produced by posterior cingulate energy hypometabolism. [Copyright &y& Elsevier]

Abnormal neuronal signaling caused by metabolic changes characterizes several neurological disorders, and in some instances metabolic interventions provide therapeutic benefits. Indeed, altering metabolism either by fasting or by maintaining a low-carbohydrate (ketogenic) diet might reduce epileptic seizures and offer neuroprotection in part because the diet increases mitochondrial biogenesis and brain energy levels. Here we focus on a novel hypothesis that a ketogenic diet-induced change in energy metabolism increases levels of ATP and adenosine, purines that are critically involved in neuron–glia interactions, neuromodulation and synaptic plasticity. Enhancing brain bioenergetics (ATP) and increasing levels of adenosine, an endogenous anticonvulsant and neuroprotective molecule, might help with understanding and treating a variety of neurological disorders. [Copyright &y& Elsevier]

There are two distinctly different pathways for the catabolism ofl-rhamnose in microorganisms. One pathway with phosphorylated intermediates was described in bacteria; here the enzymes and the corresponding gene sequences are known. The other pathway has no phosphorylated intermediates and has only been described in eukaryotic microorganisms. For this pathway, the enzyme activities have been described but not the corresponding gene sequences. The first enzyme in this catabolic pathway is the NAD-utilizingl-rhamnose 1-dehydrogenase. The enzyme was purified from the yeast Pichia stipitis, and the mass of its tryptic peptides was determined using MALDI-TOF MS. This enabled the identification of the corresponding gene, RHA1. It codes for a protein with 258 amino acids belonging to the protein family of short-chain alcohol dehydrogenases. The ORF was expressed in Saccharomyces cerevisiae. As the gene contained a CUG codon that codes for serine in P. stipitis but for leucine in S. cerevisiae, this codon has changed so that the same amino acid was expressed in S. cerevisiae. The heterologous protein showed the highest activity and affinity withl-rhamnose and a lower activity and affinity withl-mannose andl-lyxose. The enzyme was specific for NAD. A northern blot analysis revealed that transcription in P. stipitis is induced during growth onl-rhamnose but not on other carbon sources. [ABSTRACT FROM AUTHOR]

Abstract: The carcinogen and mutagen, 1-aminoanthracene, was efficiently metabolized by the fungal strain Beauveria bassiana ATCC 7159 to yield three new metabolites identified as 1-acetamido-5-[(4′-O-methyl-β-d-glucopyranosyl)oxy]anthracene, 1-acetamido-8-[(4′-O-methyl-β-d-glucopyranosyl)oxy]anthraquinone, and 1-acetamido-6-[(4′-O-methyl-β-d-glucopyranosyl)oxy]anthraquinone, together with 1-acetamidoanthracene and 1-acetamidoanthraquinone. Formation of these metabolites suggests that the metabolic pathways of 1-aminoanthracene in B. bassiana ATCC 7159 involve acetylation, oxidation, hydroxylation, and O-methylglucosylation. [Copyright &y& Elsevier]

Abstract: Catalase (CAT; EC 1.11.1.6) isolated from leaves of the halophytic plant Mesembryanthemum crystallinum is characterized by a high apparent molecular mass of about 320kDa, and high resistance to denaturing agents (10% ME). SDS-treatment breaks active oligomeric CAT into the less active and putatively dimeric form of 160kDa apparent molecular mass. Three subunits are resolved after denaturing PAGE: 79, 74 and 62kDa. Higher molecular masses of subunits coincide with increased activity of CAT. M. crystallinum leaf CAT reveals a diel variation in the resistance to denaturing factors and the stability of CAT is increased in a light-dependent manner both in C3- and in CAM-induced plants. Unchanged level of leaf CAT transcripts is documented in the diurnal cycle of C3 plants and after salinity-induced crassulacean acid metabolism (CAM). [Copyright &y& Elsevier]

Streptococcus thermophilus is unable to metabolize the galactose moiety of lactose. In this paper, we show that a transformant of S. thermophilus SMQ-301 expressing Streptococcus salivarius galK and galM was able to grow on galactose and expelled at least twofold less galactose into the medium during growth on lactose. [ABSTRACT FROM AUTHOR]

The yeast Saccharomyces cerevisiae is a facultative anaerobic organism. Under anaerobiosis, sustained growth relies on the presence of exogenously supplied unsaturated fatty acids and ergosterol that yeast is unable to synthesize in the absence of oxygen or upon haem depletion. In the absence of exogenous supplementation with unsaturated fatty acid, a net accumulation of SFA (saturated fatty acid) is observed that induces significant modification of phospholipid profile [Ferreira, Régnacq, Alimardani, Moreau-Vauzelle and Bergès (2004) Biochem. J. 378, 899–908]. In the present paper, we focus on the role of SFH2/CSR1, a hypoxic gene related to SEC14 and its involvement in lipid metabolism upon haem depletion in the absence of oleic acid supplementation. We observed that inactivation of SFH2 results in enhanced accumulation of SFA and phospholipid metabolism alterations. It results in premature growth arrest and leads to an exacerbated sensitivity to exogenous SFA. This phenotype is suppressed in the presence of exogenous oleic acid, or by a controlled expression of FAS1, one of the two genes encoding FAS. We present several lines of evidence to suggest that Sfh2p and oleic acid regulate SFA synthase in yeast at different levels: whereas oleic acid acts on FAS2 at the transcriptional level, we show that Sfh2p inhibits fatty acid synthase activity in response to haem depletion. [ABSTRACT FROM AUTHOR]

Abstract: Uridine, the major circulating pyrimidine nucleoside, participating in the regulation of a number of physiological processes, is readily uptaken into mammalian cells. The balance between anabolism and catabolism of intracellular uridine is maintained by uridine kinase, catalyzing the first step of UTP and CTP salvage synthesis, and uridine phosphorylase, catalyzing the first step of uridine degradation to β-alanine in liver. In the present study we report that the two enzymes have an additional role in the homeostatic regulation of purine and pyrimidine metabolism in brain, which relies on the salvage synthesis of nucleotides from preformed nucleosides and nucleobases, rather than on the de novo synthesis from simple precursors. The experiments were performed in rat brain extracts and cultured human astrocytoma cells. The rationale of the reciprocal regulation of purine and pyrimidine salvage synthesis in brain stands (i) on the inhibition exerted by UTP and CTP, the final products of the pyrimidine salvage pathway, on uridine kinase and (ii) on the widely accepted idea that pyrimidine salvage occurs at the nucleoside level (mostly uridine), while purine salvage is a 5-phosphoribosyl-1-pyrophosphate (PRPP)-mediated process, occurring at the nucleobase level. Thus, at relatively low UTP and CTP level, uptaken uridine is mainly anabolized to uridine nucleotides. On the contrary, at relatively high UTP and CTP levels the inhibition of uridine kinase channels uridine towards phosphorolysis. The ribose-1-phosphate is then transformed into PRPP, which is used for purine salvage synthesis. [Copyright &y& Elsevier]

Freezing survival was assessed in three species of terrestrial slugs, a holarctic but native North American species, Deroceras laeve, and two species introduced from Europe, D. reticulatum and Arion circumscriptus. The introduced species showed very poor freezing survival. Supercooling points of the introduced species were quite high (∼−3°C) and their freezing survival was very poor, limited to short-term freezing at −1.2 to −1.5°C and low ice contents (23–44%). D. laeve showed a significant elevation of supercooling point between slugs collected in the autumn (−4.8°C ± 0.5) and those collected early in the spring (−3.1°C ± 0.4). This species also showed substantial freezing survival which was greater for spring-collected slugs (100% survival of 1 h freezing at −2°C with an ice content of 65%) than for autumn animals (100% survival for 1 h at −1°C with ∼40% ice). Carbohydrate and amino acid responses to freezing and anoxia exposures were compared in the two Deroceras species. D. laeve showed a strong hyperglycemic response to freezing, a 100-fold increase in glucose levels that suggested that glucose may have a cryoprotective function in this species. D. reticulatum did not accumulate glucose and neither species produced glycerol or lactate. Both species showed typical responses to anoxia (aspartate and glutamate catabolism, alanine and succinate accumulation) and D. laeve also showed this pattern during freezing, suggesting a natural switch to anaerobiosis to support freezing survival. [ABSTRACT FROM AUTHOR]

Many regard metabolism as one of the central phenomena (or criteria) of life. Yet, the earliest infrabiological systems may have been devoid of metabolism: such systems would have been extreme heterotrophs. We do not know what level of complexity is attainable for chemical systems without enzymatic aid. Lack of template-instructed enzymatic catalysis may put a ceiling on complexity owing to inevitable spontaneous decay and wear and tear of chemodynamical machines. Views on the origin of metabolism critically depend on the assumptions concerning the sites of synthesis and consumption of organic compounds. If these sites are different, non-enzymatic origin of autotrophy is excluded. Whether autotrophy is secondary or not, it seems that protocell boundaries may have become more selective with time, concurrent with the enzymatization of the metabolic network. Primary heterotrophy and autotrophy imply pathway innovation and retention, respectively. The idea of metabolism–membrane coevolution leads to a scenario of progressive sequestration of the emerging living system from its exterior milieu. Comparative data on current protein enzymes may shed some light on such a primeval process by analogy, since two main ideas about enzymatization (the retroevolution and the patchwork scenarios) may not necessarily be mutually exclusive and the earliest enzymatic system may have used ribozymes rather than proteins. [ABSTRACT FROM AUTHOR]

In the absence of oxygen, Escherichia coli can use alternative exogenous electron acceptors, including trimethylamine oxide (TMAO), to generate energy. In this study, we showed that in contrast to the other anaerobic respiratory systems, the TMAO reductase (Tor) system was expressed during both aerobiosis and anaerobiosis. By using a torA–lacZ fusion and quantitative reverse transcription polymerase chain reaction, we established that the torCAD operon encoding the Tor system was induced in the presence of TMAO mainly during exponential phase, and that optimal induction required a certain level of DNA supercoiling. We also showed that the presence of oxygen prevented neither the biogenesis of the Tor system nor the reduction of TMAO. The physiological role of TMAO reduction during aerobiosis has not been yet established, but our experiments suggest that alkaline TMA production could enhance the growth conditions by increasing the pH of the culture. [ABSTRACT FROM AUTHOR]

The purpose of this study was to examine the responses of the oyster Crassostrea gigas to oxygen levels at subcellular and whole organism levels. Two experiments were carried out. The first experiment was designed to measure the clearance and oxygen consumption rates of oysters exposed at different concentrations of oxygen at 15, 20 and 25°C for 20 h. The goal of this first part was to estimate the hypoxic threshold for oysters below which their metabolism shifts towards anaerobiosis, by estimating the oxygen critical point (PcO2) at 15, 20 and 25°C. The second experiment was carried out to evaluate the metabolic adaptations to hypoxia for 20 days at three temperatures: 12, 15 and 20°C. The metabolic pathways were characterized by the measurement of the enzymes pyruvate kinase (PK) and phosphoenolpyruvate carboxykinase (PEPCK), the alanine and succinate content and the adenylate energy charge. Respiratory chain functioning was estimated by the measurement of the activity of the electron transport system (ETS). The values of PcO2 were 3.02±0.15, 3.43±0.20 and 3.28±0.24 mg O2 l-1 at 15, 20 and 25°C, respectively. In whole oysters, hypoxia involved the inhibition of PK whatever the temperature, but PEPCK was not stimulated. Succinate accumulated significantly only at 12°C and alanine at 12 and 15°C. A negative relationship between the PK activity and the alanine content was only found in hypoxic oysters. Finally, hypoxia increased significantly the activity of ETS. With high PcO2 values, the metabolic depression occurred quickly, showing that oysters had a low capacity to regulate their respiration when oxygen availability is reduced, particularly in the summer. [ABSTRACT FROM AUTHOR]

Abstract: Studies have proposed the involvement of oxidative stress and neuronal energy dysfunctions in the pathophysiology of bipolar disorder (BD). This study evaluates plasma levels of the oxidative/energy metabolism markers, thiobarbituric acid reactive substances (TBARS), superoxide dismutase (SOD), catalase (CAT), and neuron-specific enolase (NSE) during initial episodes of mania compared to controls in 75 subjects. Two groups of manic subjects (unmedicated n =30, and lithium-treated n =15) were age/gender matched with healthy controls (n =30). TBARS and antioxidant enzymes activity (SOD and CAT) were increased in unmedicated manic patients compared to controls. Conversely, plasma NSE levels were lower during mania than in the controls. In contrast, acute treatment with lithium showed a significant reduction in both SOD/CAT ratio and TBARS levels. These results suggest that initial manic episodes are associated with both increased oxidative stress parameters and activated antioxidant defenses, which may be related to dysfunctions on energy metabolism and neuroplasticity pathways. Antioxidant effects using lithium in mania were shown, and further studies are necessary to evaluate the potential role of these effects in the pathophysiology and therapeutics of BD. [Copyright &y& Elsevier]

Digital model of human metabolic system incorporated with real anatomical structure can be seen as an important tool in order to understand and study the processes of metabolism. This paper presented a whole body digital model framework of [18F]2-fluoro-2-deoxy-D-glucose (FDG) metabolism based on the segmented Visible Human Project (VHP) data set as the anatomical structure framework. First, the blood time-activity curve (BTAC) and the tissues time-activity curves (TTAC) were obtained from kinetic analysis. According to the obtained BTAC and TTACs, a set of corresponding values were assigned to the segmented VHP image frames. Thus a set of dynamic volume data were derived to show the 18F distribution in human body for the predetermined sampling schedule. Finally, the simulated FDG distribution was visualized by coronal, axial, and sagittal slices and volume rendering method. The model established here was especially for the metabolism of FDG; however, the modeling method is general for all tracers. The proposed model represented functional information of dynamical process of human metabolism with high visualization resolution. The results of modeling and visualization provide a useful tool for education and research on nuclear imaging, and may provide a novel technical platform for the study of pharmacokinetics. [ABSTRACT FROM AUTHOR]

Abstract: The growth of 29 human strains from the three main pathogenic species of Borrelia burgdorferi sensu lato on a solid BSK-based medium was compared in two culture atmospheres: 3% CO2 air and anaerobiosis. All strains grew under anaerobic conditions, whereas only 13 strains were able to grow in aerobiosis with 3% CO2 (). In the latter condition, 75% of the B. burgdorferi sensu stricto strains grew versus 33% of the B. garinii and B. afzelii strains. These data suggest that, especially for B. garinii and B. afzelii species, anaerobic conditions enhance growth yield and speed of low-passage Borrelia strains. [Copyright &y& Elsevier]

Abstract: A series of conformationally restricted inhibitors of human soluble epoxide hydrolase (sEH) has been developed. Inhibition potency of the described compounds ranges from 4.2μM to 1.1nM against recombinant sEH. N-(1-Acetylpiperidin-4-yl)-N′-(adamant-1-yl) urea (5a) was found to be a potent inhibitor (IC50 =7.0nM) that was also orally bioavailable in canines. [Copyright &y& Elsevier]

A mathematical model of performance describing aerobic and anaerobic energy production during exercise was applied to middle-distance running data from world records (WR) and from a group of elite runners (NL). The model is based on the assumption that, above a critical power (Pc), a continuous rate of anaerobic energy production occurs, until the entire anaerobic stores (W') are depleted. The fraction of metabolic power above Pc provided by anaerobic metabolism is denoted alpha. A second power threshold (Pt) sets the limit above which any further increase in power is met exclusively by anaerobic sources. The oxygen uptake kinetics was described by a monoexponential equation with time constant tau. The results show that the model successfully fits the WR over 1,500-5,000 m. However, in the range of distances from 800 to 5,000 m the performance over 800 and 1,000 m were overestimated. Contrary to Pc and the anaerobic contribution at steady state oxygen uptake, the estimate of W' was sensitive to the value assigned to tau in the range from 0 to 30 s. Using best performances from 1,500 to 5,000 m in NL resulted in Pc estimates not significantly different from the metabolic power at the lactate threshold. The anaerobic contribution at steady state oxygen uptake increased from zero at Pc to 8.3% (WR) and 7.8+/-3.1% (NL) at Pt. This suggests that a substantial contribution of anaerobic processes occurs in the range between Pc and Pt, even though the exercise does not elicit maximal aerobic power. [ABSTRACT FROM AUTHOR]

1. River metabolism was measured over an annual cycle at three sites distributed along a 1000 km length of the lowland Murray River, Australia. 2. Whole system metabolism was measured using water column changes in dissolved oxygen concentrations while planktonic and benthic metabolism were partitioned using light-dark bottles and benthic chambers. 3. Annual gross primary production (GPP) ranged from 775 to 1126 g O2 m−2 year−1 which in comparison with rivers of similar physical characteristics is moderately productive. 4. Community respiration (CR) ranged from 872 to 1284 g O2 m−2 year−1 so that annual net ecosystem production (NEP) was near zero, suggesting photosynthesis and respiration were balanced and that allochthonous organic carbon played a minor role in fuelling metabolism. 5. Planktonic rates of gross photosynthesis and respiration were similar to those of the total channel, indicating that plankton were responsible for much of the observed metabolism. 6. Respiration rates correlated with phytoplankton standing crop (estimated as the sum of GPP plus the chlorophyll concentration in carbon units), yielding a specific respiration rate of −1.1 g O2 g C−1 day−1. The respiration rate was equivalent to 19% of the maximum rate of phytoplankton photosynthesis, which is typical of diatoms. 7. The daily GPP per unit phytoplankton biomass correlated with the mean irradiance of the water column giving a constant carbon specific photon fixation rate of 0.35 gO2 g Chl a−1 day−1 per μmole photons m−2 s−1 (ca. 0.08 per mole photons m−2 on a carbon basis) indicating that light availability determined daily primary production. 8. Annual phytoplankton net production (NP) estimates at two sites indicated 25 and 36 g C m−2 year−1 were available to support riverine food webs, equivalent to 6% and 11% of annual GPP. 9. Metabolised organic carbon was predominantly derived from phytoplankton and was fully utilised, suggesting that food-web production was restricted by the energy supply. [ABSTRACT FROM AUTHOR]

1. Reduced metabolic rate among cave organisms compared with surface species has long been suggested as an adaptation to food shortage in cave environments. However, comparisons of metabolic rates between species have not often included closely related surface and cave species. By measuring metabolic rate across three seasons and over a range of body sizes, we examined the hypothesis that the routine metabolic rate of Gammarus acherondytes, a federally listed stygobitic amphipod, is lower than that of the closely related stygophilic Gammarus troglophilus. To determine if human activities increased the supply of organic matter to caves, we also examined the relationship between residential development and bacterial contamination in water wells. 2. For G. acherondytes, the slope of the overall relationship between oxygen consumption and body dry mass did not differ from zero and did not vary seasonally, whereas for G. troglophilus it was positive and higher in summer than in winter and spring. These results provide insights into a potential novel metabolic adaptation among stygobites. Higher metabolic rate in young G. acherondytes would allow efficient use of typically transient energy sources and a low metabolic rate at larger body sizes would increase survival through periods of food scarcity. 3. The number of wells with faecal coliform contamination was weakly but positively correlated with the number of residential building permits, indicating that surface land-use changes probably increase the availability of energy in groundwater systems inhabited by G. acherondytes. This may give stygophilic animals, with higher metabolic rates, a competitive advantage in the caves, thus reducing the abundance of stygobites such as G. acherondytes. [ABSTRACT FROM AUTHOR]

Abstract: Indoleamine 2,3-dioxygenase (EC 1.13.11.42) is a heme-containing dioxygenase which catalyzes the first and rate-limiting step in the major pathway of l-tryptophan catabolism in mammals. Much attention has recently been focused on the dioxygenase because this metabolic pathway is involved not only in a variety of physiological functions but also in many diseases. In this review, the discovery and unique catalytic properties of dioxygenase are described first, and then the recent findings regarding the dioxygenase-initiated tryptophan metabolism are summarized, with special emphasis on the detrimental role of dioxygenase in side effects of interferon-γ and interleukin-12 (by systemic tryptophan depletion), the escape of malignant tumors from immune surveillance (by immunosuppression caused by tryptophan depletion), several neurodegenerative disorders including Alzheimer’s disease (by an aberrant production of neurotoxin, quinolinic acid), and age-related cataract (due to “Kynurenilation,” a novel post-translational modification of lens proteins with tryptophan-derived UV filters). [Copyright &y& Elsevier]

Trichoderma viride was capable of growth and conidiation in the presence of high concentrations of the uncoupler 3,3′,4′,5-tetrachlorosalicylanilide (up to 100 µmol·L–1) and of the respiration inhibitor mucidin (up to 100 µmol·L–1) in both submerged and surface cultivation. When vegetative mycelia were cultivated on the solid Czapek-Dox medium with yeast autolysate under an anaerobic and CO2-containing atmosphere, the growth was observed only rarely but the microorganism survived as long as 3 months under these conditions. Major products of metabolism of both aerobic and anaerobic submerged mycelia were identified by means of 1H-NMR measurements. Major products excreted to the medium under aerobic conditions were succinic and citric acids. Major metabolites present in the submerged mycelia were γ-aminobutyric (and glutamic) acid and alanine. Under anaerobic conditions, citric acid was not excreted into the medium but ethanol appeared. Its production could not be increased upon increasing the sugar concentration. The appearance of secondary metabolites was found to be modified by oxygen availability during the mycelial growth. Results suggest that the vegetative form of T. viride is capable of fermentative metabolism characterized by the production of ethanol and succinate and that the excretion of carboxylic acids is developmentally regulated and modified by oxygen availability. [ABSTRACT FROM AUTHOR]

Abstract: A general trend of supramolecular chemistry is the building of mesoscopic-oriented nanotubes. When the typical radius of the channel almost fits the mean supramolecular cross-sectional radius, the guest supramolecule is ultraconfined in the channel. In that case, only rotational disorder around the channel axis is allowed. For sufficiently low temperatures, we expect this 2D disorder to be static on the NMR timescale, and it should reflect the local symmetry of the channels. In this article, we show that experiments performed with deuterium single crystal solid-state NMR as a function of rotation around the channel axis may lead to important information concerning the static orientational disorder of the confined supramolecules. Using an inversion method with Tikhonov regularization and a positivity constraint, that also takes into account of the nonideal pulse sequence response, the orientational probability density can be obtained from 1D experiments performed at different angles, even for significant disorder. As a first step, the method is validated on four different theoretical distributions. It is then applied to 2H NMR single crystal experiments performed on an archetype of parallel channels intergrowth compounds: selectively deuterated 1,10-decanedicarboxylic diacids in hydrogenated urea channels. The diacids form one-dimensional infinite hydrogen-bonded chains ultraconfined in urea linear channels. [Copyright &y& Elsevier]

Peter Hochachka was one of the most creative forces in the field of comparative physiology during the past half-century. His career was truly an exploratory adventure, in both intellectual and geographic senses. His broad comparative studies of metabolism in organisms as diverse as trout, tunas, oysters, squid, turtles, locusts, hummingbirds, seals, and humans revealed the adaptable features of enzymes and metabolic pathways that provide the biochemical bases for diverse lifestyles and environments. In its combined breadth and depth, no other corpus of work better illustrates the principle of "unity in diversity" that marks comparative physiology. Through his publications, his stimulating mentorship, his broad editorial services, and his continuous-and highly infectious-enthusiasm for his field, Peter Hochachka served as one of the most influential leaders in the transformation of comparative physiology. [ABSTRACT FROM AUTHOR]

The tiger beetle, Phaeoxantha klugii Chaudoir, survives the annual inundation period in Central Amazonian floodplains as a third-instar larvae submerged in the soil at approximately 29°C for up to 3.5 months. Previous studies showed an exceptional anoxia resistance in these larvae and this study investigates whether they perform anaerobiosis. Larvae collected in the field were exposed to a pure nitrogen atmosphere for 0-9 days in the laboratory. The content of lactate, alanine, free sugars and glycogen is analysed in surviving larvae. Lactate and alanine contents rise during anoxia from around 1.5 and 7 to 6-14 and 15-22 µmol g-1 fresh mass, respectively, providing evidence for anaerobic metabolism. Both compounds show a steep increase during the first 12 h and a tendency to rise further with increasing duration of anoxic conditions, indicating a significant metabolic depression within the first day. Content of free sugars and glycogen varies greatly between individuals and ranges from 0.08-2.5 and 0.05-2.9 mg g-1 fresh mass, respectively. Whether glycogen is used as metabolic substrate for anaerobiosis could not be verified. The findings for free sugars indicate that larvae apparently maintain the ability to regulate the level of glucose and/or trehalose even after 9 days of anoxia. [ABSTRACT FROM AUTHOR]

Peter W. Hochachka led a grand life of science adventure and left as his legacy a whole new field—biochemical adaptation. Oxygen was at the core of Peter''s career and his laboratory made major contributions to our understanding of how animals deal with variation in oxygen availability in many forms. He analyzed the molecular mechanisms that support facultative anaerobiosis, studied muscle exercise metabolism for high speed flight, swimming and running, investigated mammalian diving on many trips to the Antarctic to study Weddell seals, and probed the metabolic and genetic adaptations that provide optimal hypoxia tolerance for humans residing at high altitudes. His work illuminated both biochemical and physiological mechanisms that are used to optimize aerobic metabolism, to compensate for hypoxic insults, and to conserve energy by strong metabolic rate depression under anoxia. His articles, books and lectures galvanized the field with leading-edge insights and theories and he consistently challenged comparative biochemists to use their unique model systems to explore the range and breadth of animal strategies of biochemical adaptation. Lessons drawn from my training in Peter''s laboratory have led me on continuing explorations of adaptations in enzyme function, signal transduction, gene expression, and antioxidant defenses ranging over systems of anoxia tolerance, freezing survival, estivation, and mammalian hibernation. [Copyright &y& Elsevier]

It is known that the presence of ammonia inhibits hydrogen production by photosynthetic bacteria. In order to avoid it, a two-step process containing ammonia removal and hydrogen production was investigated in this study. Firstly, the effects of carbonate presence on ammonia removal by photosynthetic bacteria were investigated by the vial tests because it is known that the uptake of volatile fatty acids (VFAs) sometimes requires carbonate. The results of them showed that the presence of carbonate promoted the uptake of VFAs and ammonia. Especially, the uptake of propionate and/or butyrate required the presence of carbonate. The results of the batch experiments of two-step hydrogen production showed that the depletion of ammonia triggered hydrogen evolution. Herein, the presence of albumin did not inhibit hydrogen evolution and preferably it increased the hydrogen production rate. And the VFA-C/NH4-N ratio in substrate fed into two-step hydrogen production process should be more than 6.0. [Copyright &y& Elsevier]

The abundance of specific membrane lipids, 2-methylhopanoids, indicates that cyanobacteria played a key role in the seemingly global deposition of black shales during the early Aptian (ca. 120.5 Ma) and late Cenomanian (ca. 93.5 Ma) oceanic anoxic events. Organic matter-rich sediments deposited during these events are characterized by a 15N content typical of newly fixed N2, indicating that cyanobacterial N2 fixation was the main source for nutrient N. We propose that denitrification and anaerobic ammonium oxidation effectively cut off the return of nutrient N from the anoxic deep waters to the photic zone in the oceans, giving N2-fixing cyanobacteria a competitive advantage over algae during these oceanic anoxic events. [ABSTRACT FROM AUTHOR]

During anaerobiosis Saccharomyces cerevisiae strongly increases glycerol production to provide for non-respiratory oxidation of NADH to NAD+. We here report that respiratory-deficient cells become strictly dependent on the Gpd2p isoform of the NAD+-linked glycerol-3-phosphate dehydrogenase (Gpd). The growth inhibition of respiratory incompetent cox18Δ cells lacking GPD2 is reversed by the addition of acetoin, an alternative sink for NADH oxidation. Growth is also restored by addition of lysine or glutamic acid/glutamine, the synthesis of which involves production of mitochondrial NADH. Lysine produced a stronger growth stimulating effect than glutamic acid consistent with an upregulated expression of the IDP3 gene for peroxisomal synthesis of the glutamate precursor aa-ketoglutarate. Gpd2p is known to be a cytosolic protein but possesses a classical mitochondrial presequence, which we show is sufficient for mitochondrial targeting. A partial mitochondrial localization of Gpd2p will provide for establishment of intramitochondrial redox balance under non-respiratory conditions. Gpd1p, the other Gpd isoform, is partly cytosolic and partly peroxisomal and becomes more strictly peroxisomal in respiratory-deficient mutants. The different cellular distribution of Gpd1p and Gpd2p thus appears to be the main reason Gpd1p cannot substitute for Gpd2p in cox18Δgpd2Δ cells, despite similar kinetic characteristics of the two iso-enzymes. [ABSTRACT FROM AUTHOR]

An important functional advantage of hypoxic hypometabolism is that it blunts the acid–base consequences of hypoxia. Hypoxia can lead to anaerobiosis and metabolic acidosis and, in animals that are apneic, to respiratory acidosis. A fall in blood and tissue pH is a major limiting factor in hypoxic tolerance and a variety of strategies occur in vertebrates, in concert with hypometabolism, to respond to this acid–base challenge. These include sequestering of lactic acid away from the circulating blood during the hypoxic exposure, either in underperfused tissues or in mineralized tissues, supplementing extracellular buffering by releasing bone mineral into the circulation, and utilizing alternative metabolic pathways for anaerobiosis to produce ethanol rather than lactate as the principal end-product. For submerged air-breathing ectotherms, effective cutaneous O2 and CO2 exchange can also allow an animal to avoid or minimize both anaerobiosis and respiratory acidosis. These responses serve to maintain a viable acid–base state in the body and to extend the time that the hypoxic stress can be endured. [Copyright &y& Elsevier]

Actinobacillus pleuropneumoniae is the causative agent of an economically significant form of porcine pleuropneumonia. This bacterium produces four distinct RTX toxins (ApxI–ApxIV) that play a key role in its pathogenesis, but further characterization of these hemolytic toxins is needed to identify the environmental signals and genes that affect their production during infection. In this report, we examined the effect of oxygen limitation on the production of ApxI and ApxII, the two RTX toxins that are produced by all highly virulent strains in North America. Batch cultures of ApxI- and ApxII-producing strains were grown in heart infusion broth supplemented with NAD, and samples were prepared throughout the growth curve. We compared batch cultures with normal oxygen levels to those that were maintained in an oxygen-depleted state. ApxI and ApxII hemolytic activity were nearly identical under both growth conditions. The level of toxin activity was confirmed by examination of extracellular ApxI concentrations and apxII mRNA levels. In addition, toxin activity examined on blood agar plates grown aerobically or anaerobically showed no significant difference. These results have important implications for the disease state where high-density growth is likely to result in local anaerobic or microaerophilic environments. [Copyright &y& Elsevier]

From a collection of over 2800 Salmonella enterica subspecies Enterica serotype Typhimurium F98 Tn5-TC1 insertion mutants 14 were identified as expressing growth-non-suppressive phenotype under strict anaerobic conditions. Sequence analysis of regions flanking the Tn insertions revealed that most of the selected mutants were defective in genes contributing to the anaerobic fumarate uptake and generation (insertions in dcuA, dcuB and aspA), or to the anaerobic l-arginine utilisation pathway (insertions in STM4467 encoding a putative arginine deiminase, and in between speF encoding ornithine decarboxylase and kdpE coding a response regulator protein). Mutants defective in flagellum synthesis (flhA) were also identified. In contrast to the in vitro results, all the mutants colonised 1-day-old chicks efficiently and suppressed the super-infection of chicks by the parent strain. This clearly indicates that neither of the metabolic pathways mentioned above nor motility play essential roles in lower intestinal tract colonisation. [Copyright &y& Elsevier]

Isoflavonoids found in legumes, such as soybeans, are converted by intestinal bacteria to metabolites that might have increased or decreased estrogenic activity. Variation in the effects of dietary isoflavonoids among individuals has been attributed to differences in their metabolism by intestinal bacteria. To investigate this variation, the metabolism of the isoflavonoid daidzein by bacteria from ten fecal samples, provided at different times by six individuals on soy-containing diets, was compared. After anaerobic incubation of bacteria with daidzein for 2 weeks, four samples had metabolized daidzein and six samples had not. Three of the positive samples were from individuals whose microflora had not metabolized daidzein in previous samples. Dihydrodaidzein was observed in one sample, dihydrodaidzein and equol in another sample, and equol and O-desmethylangolensin in two other samples. These results corroborate the hypothesis that the microflora of the gastrointestinal tract of an individual influences the particular isoflavone metabolites produced following consumption. [ABSTRACT FROM AUTHOR]