There is evidence for beneficial effects of acute and long-term exercise interventions on several forms of memory, including procedural motor learning. In the present study we examined how performing ...a single bout of continuous moderate intensity aerobic exercise would impact motor skill acquisition and retention in young healthy adults, compared to a period of rest. We hypothesized that exercise would improve motor skill acquisition and retention, compared to motor practice alone.
Sixteen healthy adults completed sessions of aerobic exercise or seated rest that were immediately followed by practice of a novel motor task (practice). Exercise consisted of 30 minutes of continuous cycling at 60% peak O2 uptake. Twenty-four hours after practice, we assessed motor learning with a no-exercise retention test (retention). We also quantified changes in offline motor memory consolidation, which occurred between practice and retention (offline). Tracking error was separated into indices of temporal precision and spatial accuracy.
There were no differences between conditions in the timing of movements during practice (p = 0.066), at retention (p = 0.761), or offline (p = 0.966). However, the exercise condition enabled participants to maintain spatial accuracy during practice (p = 0.477); whereas, following rest performance diminished (p = 0.050). There were no significant differences between conditions at retention (p = 0.532) or offline (p = 0.246).
An acute bout of moderate-intensity aerobic exercise facilitated the maintenance of motor performance during skill acquisition, but did not influence motor learning. Given past work showing that pairing high intensity exercise with skilled motor practice benefits learning, it seems plausible that intensity is a key modulator of the effects of acute aerobic exercise on changes in complex motor behavior. Further work is necessary to establish a dose-response relationship between aerobic exercise and motor learning.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Sulfoquinovose (SQ), a derivative of glucose with a C6-sulfonate, is produced by photosynthetic organisms and is the headgroup of the sulfolipid sulfoquinovosyl diacylglycerol. The degradation of SQ ...allows recycling of its elemental constituents and is important in the global sulfur and carbon biogeochemical cycles. Degradation of SQ by bacteria is achieved through a range of pathways that fall into two main groups. One group involves scission of the 6-carbon skeleton of SQ into two fragments with metabolic utilization of carbons 1-3 and excretion of carbons 4-6 as dihydroxypropanesulfonate or sulfolactate that is biomineralized to sulfite/sulfate by other members of the microbial community. The other involves the complete metabolism of SQ by desulfonylation involving cleavage of the C-S bond to release sulfite and glucose, the latter of which can enter glycolysis. The discovery of sulfoglycolytic pathways has revealed a wide range of novel enzymes and SQ binding proteins. Biochemical and structural characterization of the proteins and enzymes in these pathways have illuminated how the sulfonate group is recognized by Nature's catalysts, supporting bioinformatic annotation of sulfoglycolytic enzymes, and has identified functional and structural relationships with the pathways of glycolysis.
A biochemical, structural and mechanistic perspective on the pathways of sulfoglycolysis for catabolism of the sulfosugar sulfoquinovose.
Key points
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The discovery of microRNAs (miRNAs) has established new mechanisms that control health, but little is known about the regulation of skeletal muscle miRNAs in response to exercise.
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...This study investigated components of the miRNA biogenesis pathway (Drosha, Dicer and Exportin‐5), muscle enriched miRNAs, (miR‐1, ‐133a, ‐133b and 206), and several miRNAs dysregulated in muscle myopathies, and showed that 3 h following an acute exercise bout, Drosha, Dicer and Exportin‐5, as well as miR‐1, ‐133a, ‐133‐b and miR‐181a were all increased, while miR‐9, ‐23a, ‐23b and ‐31 were decreased.
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Short‐term training increased miR‐1 and miR‐29b, while miR‐31 remained decreased.
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Negative correlations were observed between miR‐9 and HDAC4 protein, miR‐31 and HDAC4 protein and between miR‐31 and NRF1 protein, 3 h after exercise.
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miR‐31 binding to the HDAC4 and NRF1 3′ untranslated region (UTR) reduced luciferase reporter activity.
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Exercise rapidly and transiently regulates several miRNA species potentially involved in the regulation of skeletal muscle regeneration, gene transcription and mitochondrial biogenesis.
The identification of microRNAs (miRNAs) has established new mechanisms that control skeletal muscle adaptation to exercise. The present study investigated the mRNA regulation of components of the miRNA biogenesis pathway (Drosha, Dicer and Exportin‐5), muscle enriched miRNAs, (miR‐1, ‐133a, ‐133b and ‐206), and several miRNAs dysregulated in muscle myopathies (miR‐9, ‐23, ‐29, ‐31 and ‐181). Measurements were made in muscle biopsies from nine healthy untrained males at rest, 3 h following an acute bout of moderate‐intensity endurance cycling and following 10 days of endurance training. Bioinformatics analysis was used to predict potential miRNA targets. In the 3 h period following the acute exercise bout, Drosha, Dicer and Exportin‐5, as well as miR‐1, ‐133a, ‐133‐b and ‐181a were all increased. In contrast miR‐9, ‐23a, ‐23b and ‐31 were decreased. Short‐term training increased miR‐1 and ‐29b, while miR‐31 remained decreased. Negative correlations were observed between miR‐9 and HDAC4 protein (r=−0.71; P= 0.04), miR‐31 and HDAC4 protein (r =−0.87; P= 0.026) and miR‐31 and NRF1 protein (r =−0.77; P= 0.01) 3 h following exercise. miR‐31 binding to the HDAC4 and NRF1 3′ untranslated region (UTR) reduced luciferase reporter activity. Exercise rapidly and transiently regulates several miRNA species in muscle. Several of these miRNAs may be involved in the regulation of skeletal muscle regeneration, gene transcription and mitochondrial biogenesis. Identifying endurance exercise‐mediated stress signals regulating skeletal muscle miRNAs, as well as validating their targets and regulatory pathways post exercise, will advance our understanding of their potential role/s in human health.
The objectives of the present study were to evaluate the impact of a single bout of high-intensity aerobic exercise on 1) long-term potentiation (LTP)-like neuroplasticity via response to paired ...associative stimulation (PAS) and 2) the temporal and spatial components of sequence-specific implicit motor learning. Additionally, relationships between exercise-induced increases in systemic brain-derived neurotrophic factor (BDNF) and response to PAS and motor learning were evaluated. Sixteen young healthy participants completed six experimental sessions, including the following: 1) rest followed by PAS; 2) aerobic exercise followed by PAS; 3) rest followed by practice of a continuous tracking (CT) task and 4) a no-exercise 24-h retention test; and 5) aerobic exercise followed by CT task practice and 6) a no-exercise 24-h retention test. The CT task included an embedded repeated sequence allowing for evaluation of sequence-specific implicit learning. Slope of motor-evoked potential recruitment curves generated with transcranial magnetic stimulation showed larger increases when PAS was preceded by aerobic exercise (59.8% increase) compared with rest (14.2% increase, P = 0.02). Time lag of CT task performance on the repeated sequence improved under the aerobic exercise condition from early (-100.8 ms) to late practice (-75.2 ms, P < 0.001) and was maintained at retention (-79.2 ms, P = 0.004) but did not change under the rest condition (P > 0.16). Systemic BDNF increased on average by 3.4-fold following aerobic exercise (P = 0.003), but the changes did not relate to neurophysiological or behavioral measures (P > 0.42). These results indicate that a single bout of high-intensity aerobic exercise can prime LTP-like neuroplasticity and promote sequence-specific implicit motor learning.
Rhizobia are nitrogen-fixing bacteria that engage in symbiotic relationships with plant hosts but can also persist as free-living bacteria in the soil and rhizosphere. Here, we show that free-living
...SRDI565 can grow on the sulfosugar sulfoquinovose (SQ) or the related glycoside SQ-glycerol using a sulfoglycolytic Entner-Doudoroff (sulfo-ED) pathway, resulting in production of sulfolactate (SL) as the major metabolic end product. Comparative proteomics supports the involvement of a sulfo-ED operon encoding an ABC transporter, sulfo-ED enzymes, and an SL exporter. Consistent with an oligotrophic lifestyle, proteomics data revealed little change in expression of the sulfo-ED proteins during growth on SQ versus mannitol, a result confirmed through biochemical assay of sulfoquinovosidase activity in cell lysates. Metabolomics analysis showed that growth on SQ involves gluconeogenesis to satisfy metabolic requirements for glucose-6-phosphate and fructose-6-phosphate. Metabolomics analysis also revealed the unexpected production of small amounts of sulfofructose and 2,3-dihydroxypropanesulfonate, which are proposed to arise from promiscuous activities of the glycolytic enzyme phosphoglucose isomerase and a nonspecific aldehyde reductase, respectively. The discovery of a rhizobium isolate with the ability to degrade SQ builds our knowledge of how these important symbiotic bacteria persist within soil.
Sulfonate sulfur is a major form of organic sulfur in soils but requires biomineralization before it can be utilized by plants. Very little is known about the biochemical processes used to mobilize sulfonate sulfur. We show that a rhizobial isolate from soil,
SRDI565, possesses the ability to degrade the abundant phototroph-derived carbohydrate sulfonate SQ through a sulfoglycolytic Entner-Doudoroff pathway. Proteomics and metabolomics demonstrated the utilization of this pathway during growth on SQ and provided evidence for gluconeogenesis. Unexpectedly, off-cycle sulfoglycolytic species were also detected, pointing to the complexity of metabolic processes within cells under conditions of sulfoglycolysis. Thus, rhizobial metabolism of the abundant sulfosugar SQ may contribute to persistence of the bacteria in the soil and to mobilization of sulfur in the pedosphere.
This study examines a perovskite-based graphene field effect transistor (P-GFET) device for X-ray detection. The device architecture consisted of a commercially available GFET-S20 chip, produced by ...Graphenea, with a layer of methylammonium lead iodide (MAPbI3) perovskite spin coated onto the top of it. This device was exposed to the field of a molybdenum target X-ray tube with beam settings between 20-60 kVp (X-ray tube voltage) and 30-300 uA (X-ray tube current). Dose measurements were taken with an ion-chamber and thermo-luminescent dosimeters and used to determine the sensitivity of the device as a function of the X-ray tube voltage and current, as well as source-drain voltage. The X-ray tube was also simulated in this work with GEANT4 and MCNP to determine the dose rate and power incident on the device during irradiation. These simulations were then used to determine the responsivity as a function of the X-ray tube voltage and current, as well as the source-drain voltage. Overall, a strong positive correlation between sensitivity and source-drain voltage was found. Conversely, the sensitivity was found to decrease - roughly exponentially - as a function of both the X-ray tube current and energy. Similar trends were seen with responsivity. We report the models used for the study as well as address the feasibility of the device as a low-energy (< 70 keV) X-ray photon detector.
The solute-binding protein (SBP) components of periplasmic binding protein-dependent ATP-binding cassette (ABC)-type transporters often possess exquisite selectivity for their cognate ligands. ...Maltose binding protein (MBP), the best studied of these SBPs, has been extensively used as a fusion partner to enable the affinity purification of recombinant proteins. However, other SBPs and SBP-ligand based affinity systems remain underexplored. The sulfoquinovose-binding protein SmoF, is a substrate-binding protein component of the ABC transporter cassette in
Agrobacterium tumefaciens
involved in importing sulfoquinovose (SQ) and its derivatives for SQ catabolism. Here, we show that SmoF binds with high affinity to the octyl glycoside of SQ (octyl-SQ), demonstrating remarkable tolerance to extension of the anomeric substituent. The 3D X-ray structure of the SmoFoctyl-SQ complex reveals accommodation of the octyl chain, which projects to the protein surface, providing impetus for the synthesis of a linker-equipped SQ-amine using a thiolene reaction as a key step, and its conjugation to cyanogen bromide modified agarose. We demonstrate the successful capture and release of SmoF from SQ-agarose resin using SQ as competitive eluant, and selectivity for release
versus
other organosulfonates. We show that SmoF can be captured and purified from a cell lysate, demonstrating the utility of SQ-agarose in capturing SQ binding proteins from complex mixtures. The present work provides a pathway for development of capture-and-release affinity resins for the discovery and study of SBPs.
Conjugation of sulfoquinovose to agarose
via
a linker provided SQ-agarose, which captures a sulfoquinovose-binding protein, and releases it upon elution with sulfoquinovose.
A high-resolution mapping and sampling study of the Gakkel ridge was accomplished during an international ice-breaker expedition to the high Arctic and North Pole in summer 2001. For this ...slowest-spreading endmember of the global mid-ocean-ridge system, predictions were that magmatism should progressively diminish as the spreading rate decreases along the ridge, and that hydrothermal activity should be rare. Instead, it was found that magmatic variations are irregular, and that hydrothermal activity is abundant. A 300-kilometre-long central amagmatic zone, where mantle peridotites are emplaced directly in the ridge axis, lies between abundant, continuous volcanism in the west, and large, widely spaced volcanic centres in the east. These observations demonstrate that the extent of mantle melting is not a simple function of spreading rate: mantle temperatures at depth or mantle chemistry (or both) must vary significantly along-axis. Highly punctuated volcanism in the absence of ridge offsets suggests that first-order ridge segmentation is controlled by mantle processes of melting and melt segregation. The strong focusing of magmatic activity coupled with faulting may account for the unexpectedly high levels of hydrothermal activity observed.
Celotno besedilo
Dostopno za:
DOBA, IJS, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
To compare blood alkalosis, gastrointestinal symptoms and indicators of strong ion difference after ingestion of 500 mg.kg-1 BM sodium citrate over four different periods.
Sixteen healthy and active ...participants ingested 500 mg.kg-1 BM sodium citrate in gelatine capsules over a 15, 30, 45 or 60 min period using a randomized cross-over experimental design. Gastrointestinal symptoms questionnaires and venous blood samples were collected before ingestion, immediately post-ingestion, and every 30 min for 480 min post-ingestion. Blood samples were analysed for blood pH, HCO3-, Na+, Cl- and plasma citrate. Linear mixed models were used to estimate the effect of the ingestion protocols.
For all treatments, blood HCO3- was significantly elevated above baseline for the entire 480 min post-ingestion period, and peak occurred 180 min post-ingestion. Blood HCO3- and pH were significantly elevated above baseline and not significantly below the peak between 150-270 min post-ingestion. Furthermore, blood pH and HCO3- were significantly lower for the 60 min ingestion period when compared to the other treatments. Gastrointestinal symptoms were minor for all treatments; the mean total session symptoms ratings (all times summed together) were between 9.8 and 11.6 from a maximum possible rating of 720.
Based on the findings of this investigation, sodium citrate should be ingested over a period of less than 60 min (15, 30 or 45 min), and completed 150-270 min before exercise.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
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