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Flaveria is a leading model for C4 plant evolution due to the presence of a dozen C3-C4 intermediate species, many of which are associated with a phylogenetic complex centered around Flaveria linearis. To investigate C4 evolution in Flaveria, we updated the Flaveria phylogeny and evaluated gas exchange, starch δ13C, and activity of C4 cycle enzymes in 19 Flaveria species and 28 populations within the F. linearis complex. A principal component analysis identified six functional clusters: (1) C3, (2) sub-C2, (3) full C2, (4) enriched C2, (5) sub-C4, and (6) fully C4 species. The sub-C2 species lacked a functional C4 cycle, while a gradient was present in the C2 clusters from little to modest C4 cycle activity as indicated by δ13C and enzyme activities. Three Yucatan populations of F. linearis had photosynthetic CO2 compensation points equivalent to C4 plants but showed little evidence for an enhanced C4 cycle, indicating they have an optimized C2 pathway that recaptures all photorespired CO2 in the bundle sheath (BS) tissue. All C2 species had enhanced aspartate aminotransferase activity relative to C3 species and most had enhanced alanine aminotransferase activity. These aminotransferases form aspartate and alanine from glutamate and in doing so could help return photorespiratory nitrogen (N) from BS to mesophyll cells, preventing glutamate feedback onto photorespiratory N assimilation. Their use requires upregulation of parts of the C4 metabolic cycle to generate carbon skeletons to sustain N return to the mesophyll, and thus could facilitate the evolution of the full C4 photosynthetic pathway.
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Asteraceae , Flaveria , Flaveria/genética , Flaveria/metabolismo , Filogenia , Asteraceae/metabolismo , Dióxido de Carbono/metabolismo , Hojas de la Planta/genética , Hojas de la Planta/metabolismo , Fotosíntesis/genética , Plantas/metabolismoRESUMEN
Solar-induced chlorophyll fluorescence (SIF) provides an opportunity to rapidly and non-destructively investigate how plants respond to stress. Here, we explored the potential of SIF to detect the effects of elevated O3 on soybean in the field where soybean was subjected to ambient and elevated O3 throughout the growing season in 2021. Exposure to elevated O3 resulted in a significant decrease in canopy SIF at 760 nm (SIF760), with a larger decrease in the late growing season (36%) compared with the middle growing season (13%). Elevated O3 significantly decreased the fraction of absorbed photosynthetically active radiation by 8-15% in the middle growing season and by 35% in the late growing stage. SIF760 escape ratio (fesc) was significantly increased under elevated O3 by 5-12% in the late growth stage due to a decrease of leaf chlorophyll content and leaf area index. Fluorescence yield of the canopy was reduced by 5-11% in the late growing season depending on the fesc estimation method, during which leaf maximum carboxylation rate and maximum electron transport were significantly reduced by 29% and 20% under elevated O3. These results demonstrated that SIF could capture the elevated O3 effect on canopy structure and acceleration of senescence in soybean and provide empirical support for using SIF for soybean stress detection and phenotyping.
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Ozono , Fotosíntesis , Glycine max , Ozono/farmacología , Fluorescencia , Clorofila , Hojas de la Planta , AceleraciónRESUMEN
OBJECTIVE: To compare prostate artery embolisation (PAE) to the combination of tamsulosin and dutasteride therapy as a potential first-line therapy for obstructive benign prostatic hyperplasia (BPH) in treatment-naïve patients in the 'Prostate Embolisation AS first-line therapY compAred to meDication in treatment naïVe men with prostAte eNlargement, a randomised ControllEd trial' (P-EASY ADVANCE). PATIENTS AND METHODS: A total of 39 men with enlarged prostates, moderate-severe lower urinary tract symptoms (LUTS) and obstructed/equivocal urodynamic studies (UDS), and who had no prior treatment for BPH, were randomised to receive either combined medical therapy with tamsulosin and dutasteride (medication) or PAE. Follow-up UDS, International Prostate Symptom Score (IPSS), uroflowmetry and ultrasound were performed at short- to medium-term intervals following interventions and compared to baseline. RESULTS: The medication and PAE treatment groups had similar baseline characteristics, including prostate volumes (87.8 and 85.4 mL respectively), maximum urinary flow rate (Qmax; 6.5 and 6.6 mL/s, respectively), IPSS (19.5 and 21, respectively) and obstructed UDS (79% and 74%, respectively). Both interventions improved voiding and bladder outflow obstruction from baseline, with more patients unobstructed after PAE (63%) compared to medication (28%) (P = 0.03). PAE patients had significantly greater reductions in prostate size (P < 0.001), incomplete emptying (P = 0.002), total IPSS (P = 0.032), Qmax (P = 0.006) and quality of life (P = 0.001). Altered ejaculation, erectile dysfunction and nausea were more common in the medication group. CONCLUSION: Prostate artery embolisation was more effective than combined medical therapy at reducing urinary obstruction, decreasing prostate volume and improving LUTS in patients with BPH who had not previously been treated. This is the first randomised control study to compare PAE and combined medical therapy in exclusively treatment-naïve patients and raises the potential of PAE as an alternative early treatment option for BPH. Further randomised comparative trials are planned to further validate the role of PAE in mitigating obstructive BPH.
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Ozone (O3 ) is a damaging air pollutant to crops. As one of the most reactive oxidants known, O3 rapidly forms other reactive oxygen species (ROS) once it enters leaves through stomata. Those ROS in turn can cause oxidative stress, reduce photosynthesis, accelerate senescence, and decrease crop yield. To improve and adapt our feed, fuel, and food supply to rising O3 pollution, a number of Free Air Concentration Enrichment (O3 -FACE) facilities have been developed around the world and have studied key staple crops. In this review, we provide an overview of the FACE facilities and highlight some of the lessons learned from the last two decades of research. We discuss the differences between C3 and C4 crop responses to elevated O3 , the possible trade-off between productivity and protection, genetic variation in O3 response within and across species, and how we might leverage this observed variation for crop improvement. We also highlight the need to improve understanding of the interaction between rising O3 pollution and other aspects of climate change, notably drought. Finally, we propose the use of globally modeled O3 data that are available at increasing spatial and temporal resolutions to expand upon the research conducted at the limited number of global O3 -FACE facilities.
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Contaminantes Atmosféricos/efectos adversos , Cambio Climático , Productos Agrícolas/fisiología , Ozono/efectos adversos , Fotosíntesis , Agricultura , Contaminación del Aire/efectos adversos , Dióxido de Carbono/metabolismo , Productos Agrícolas/efectos de los fármacos , Productos Agrícolas/genética , Sequías , Variación Genética , Estrés Oxidativo , Fotosíntesis/efectos de los fármacosRESUMEN
The rotation of Paracoccus denitrificans F1-ATPase (PdF1) was studied using single-molecule microscopy. At all concentrations of adenosine triphosphate (ATP) or a slowly hydrolyzable ATP analog (ATPγS), above or below Km, PdF1 showed three dwells per turn, each separated by 120°. Analysis of dwell time between steps showed that PdF1 executes binding, hydrolysis, and probably product release at the same dwell. The comparison of ATP binding and catalytic pauses in single PdF1 molecules suggested that PdF1 executes both elementary events at the same rotary position. This point was confirmed in an inhibition experiment with a nonhydrolyzable ATP analog (AMP-PNP). Rotation assays in the presence of adenosine diphosphate (ADP) or inorganic phosphate at physiological concentrations did not reveal any obvious substeps. Although the possibility of the existence of substeps remains, all of the datasets show that PdF1 is principally a three-stepping motor similar to bacterial vacuolar (V1)-ATPase from Thermus thermophilus This contrasts with all other known F1-ATPases that show six or nine dwells per turn, conducting ATP binding and hydrolysis at different dwells. Pauses by persistent Mg-ADP inhibition or the inhibitory ζ-subunit were also found at the same angular position of the rotation dwell, supporting the simplified chemomechanical scheme of PdF1 Comprehensive analysis of rotary catalysis of F1 from different species, including PdF1, suggests a clear trend in the correlation between the numbers of rotary steps of F1 and Fo domains of F-ATP synthase. F1 motors with more distinctive steps are coupled with proton-conducting Fo rings with fewer proteolipid subunits, giving insight into the design principle the F1Fo of ATP synthase.
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Mitocondrias/metabolismo , Paracoccus denitrificans/metabolismo , ATPasas de Translocación de Protón/metabolismo , Adenosina Difosfato/metabolismo , Adenosina Trifosfato/metabolismo , Hidrólisis , Cinética , Rotación , Thermus thermophilus/metabolismoRESUMEN
The leaf economics spectrum (LES) describes multivariate correlations in leaf structural, physiological and chemical traits, originally based on diverse C3 species grown under natural ecosystems. However, the specific contribution of C4 species to the global LES is studied less widely. C4 species have a CO2 concentrating mechanism which drives high rates of photosynthesis and improves resource use efficiency, thus potentially pushing them towards the edge of the LES. Here, we measured foliage morphology, structure, photosynthesis, and nutrient content for hundreds of genotypes of the C4 grass Miscanthus× giganteus grown in two common gardens over two seasons. We show substantial trait variations across M.× giganteus genotypes and robust genotypic trait relationships. Compared to the global LES, M.× giganteus genotypes had higher photosynthetic rates, lower stomatal conductance, and less nitrogen content, indicating greater water and photosynthetic nitrogen use efficiency in the C4 species. Additionally, tetraploid genotypes produced thicker leaves with greater leaf mass per area and lower leaf density than triploid genotypes. By expanding the LES relationships across C3 species to include C4 crops, these findings highlight that M.× giganteus occupies the boundary of the global LES and suggest the potential for ploidy to alter LES traits.
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Ecosistema , Poaceae , Poaceae/genética , Tetraploidía , Triploidía , Fotosíntesis/fisiología , Hojas de la Planta/fisiología , NitrógenoRESUMEN
BACKGROUND: Depressive symptoms are common in patients with Parkinson's disease and depression is a significant predictor of functional impairment, reduced quality of life and general well-being in Parkinson's disease. Despite the high prevalence of depression, evidence on the effectiveness and tolerability of antidepressants in this population is limited. The primary aim of this trial is to establish the clinical and cost effectiveness of escitalopram and nortriptyline for the treatment of depression in Parkinson's disease. METHODS: This is a multi-centre, double-blind, randomised placebo-controlled trial in 408 people with Parkinson's disease with subsyndromal depression, major depressive disorder or persistent depressive disorder and a Beck Depression Inventory-II (BDI-II) score of 14 or above. Participants will be randomised into one of three groups, receiving either escitalopram, nortriptyline or placebo for 12 months. Trial participation is face-to-face, hybrid or remote. The primary outcome measure is the BDI-II score following 8 weeks of treatment. Secondary outcomes will be collected at baseline, 8, 26 and 52 weeks and following withdrawal, including severity of anxiety and depression scores as well as Parkinson's disease motor severity, and ratings of non-motor symptoms, cognitive function, health-related quality of life, levodopa-equivalence dose, changes in medication, overall clinical effectiveness, capability, health and social care resource use, carer health-related quality of life, adverse effects and number of dropouts. DISCUSSION: This trial aims to determine the effectiveness of escitalopram and nortriptyline for reducing depressive symptoms in Parkinson's disease over 8 weeks, to provide information on the effect of these medications on anxiety and other non-motor symptoms in PD and on impact on patients and caregivers, and to examine their effect on change in motor severity. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT03652870 Date of registration - 29th August 2018.
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Trastorno Depresivo Mayor , Enfermedad de Parkinson , Humanos , Enfermedad de Parkinson/complicaciones , Enfermedad de Parkinson/tratamiento farmacológico , Trastorno Depresivo Mayor/tratamiento farmacológico , Calidad de Vida , Escitalopram , Antidepresivos/uso terapéutico , Nortriptilina/uso terapéutico , Resultado del Tratamiento , Método Doble Ciego , Ensayos Clínicos Controlados Aleatorios como Asunto , Estudios Multicéntricos como AsuntoRESUMEN
Introduction: Finite resources limit the amount of time EMS agencies can dedicate to continuing education in pediatric emergencies. EMS instructors need effective, efficient, and affordable educational strategies for these high-risk, low frequency events.Objective: To compare the effectiveness of four training methods in management of pediatric emergencies for paramedics.Methods: A validated, performance-based, simulated clinical assessment module was used to provide a baseline measurement of paramedics' resuscitation skills during three simulated pediatric emergencies. Educational modules were developed that targeted deficiencies identified by the baseline assessment, including advanced pediatric life support skills, airway management, use of the Broselow-Luten Tape®, pediatric drug dose calculations and drug delivery, seizure management, and trauma assessment. Paramedics from five EMS agencies in Michigan were randomized to four education intervention groups. The control group used an existing, online, continuing education course. Three experimental groups were exposed to the same content during five, one-hour sessions conducted over 2.5 years. Instruction was delivered using high-fidelity, simulated case-based training, low-fidelity simulation training, or lecture with procedural skills lab, based on group assignment. After the training, all groups were tested within 4-6 months using methods identical to baseline testing.Results: One hundred forty-seven subjects completed the study. There were no differences in baseline skill levels among the four groups. Only the low fidelity simulation training group demonstrated improvement of combined scenario scores (p = 0.0008). Scores for targeted skills improved in one scenario in the high-fidelity group, two in the low-fidelity group, one in the lecture/lab group, and none in the control group.Conclusions: Although improvements in those skills included in the training were found in three groups, two hours of training in pediatric emergencies per year was insufficient to produce a substantial improvement overall. Expensive, high-fidelity simulators were not necessary for teaching pediatric resuscitation skills to paramedics; instructive scenarios using low-fidelity manikins and debriefings appear to be adequate. The content delivered by an online refresher course did not provide any improvement in performance as measured by simulated, case-based assessments.
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Urgencias Médicas , Servicios Médicos de Urgencia , Técnicos Medios en Salud/educación , Niño , Competencia Clínica , Educación Continua , HumanosRESUMEN
PURPOSE: To evaluate the relationship between lifestyle behaviours, emotional health factors, and low back pain (LBP) resilience. METHODS: This retrospective longitudinal study utilised 1,065 twins with a recent history of LBP from the Washington State Twin Registry. A lifestyle behaviour score was built using variables of body mass index, physical activity engagement, sleep quality, smoking status, and alcohol consumption. An emotional health score was built using variables of the absence of depressed mood, perceived stress, and active coping. The main outcome was LBP resilience, assessed as recovery ("bouncing back"), and sustainability (maintaining high levels of function despite LBP). RESULTS: After adjusting for covariates, there was no relationship between the lifestyle behaviour score (OR 1.05, 95% CI 0.97-1.15, p = 0.218) and the emotional health score (OR 1.08, 95% CI 0.98-1.19, p = 0.142) with the likelihood of recovering from LBP. There was however, evidence of a positive association between the lifestyle behaviour score (ß 0.20, 95% CI 0.04-0.36, p = 0.013), the emotional health score (ß 0.22, 95% CI 0.00-0.43, p = 0.049), and greater levels of sustainability. These results were confirmed by a within-pair analysis (lifestyle behaviour score: ß 1.79, 95% CI 0.05-3.53, p = 0.043) and (emotional health score: ß 0.52, 95% CI 0.09-0.96, p = 0.021) adjusting for genetic and early shared environmental confounding. CONCLUSION: Findings from this study suggest that people who adopt optimal lifestyle behaviours and positive emotional factors are more likely to be resilient and maintain high levels of function despite suffering from LBP.
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Dolor de la Región Lumbar , Humanos , Dolor de la Región Lumbar/epidemiología , Estudios Retrospectivos , Estudios Longitudinales , Estilo de Vida , GemelosRESUMEN
BACKGROUND: Ensuring access to healthcare is a complex, multi-dimensional health challenge. Since the inception of the coronavirus pandemic, this challenge is more pressing. Some dimensions of access are difficult to quantify, namely characteristics that influence healthcare services to be both acceptable and appropriate. These link to a patient's acceptance of services that they are to receive and ensuring appropriate fit between services and a patient's specific healthcare needs. These dimensions of access are particularly evident in rural health systems where additional structural barriers make accessing healthcare more difficult. Thus, it is important to examine healthcare access barriers in rural-specific areas to understand their origin and implications for resolution. METHODS: We used qualitative methods and a convenience sample of healthcare providers who currently practice in the rural US state of Montana. Our sample included 12 healthcare providers from diverse training backgrounds and specialties. All were decision-makers in the development or revision of patients' treatment plans. Semi-structured interviews and content analysis were used to explore barriers-appropriateness and acceptability-to healthcare access in their patient populations. Our analysis was both deductive and inductive and focused on three analytic domains: cultural considerations, patient-provider communication, and provider-provider communication. Member checks ensured credibility and trustworthiness of our findings. RESULTS: Five key themes emerged from analysis: 1) a friction exists between aspects of patients' rural identities and healthcare systems; 2) facilitating access to healthcare requires application of and respect for cultural differences; 3) communication between healthcare providers is systematically fragmented; 4) time and resource constraints disproportionately harm rural health systems; and 5) profits are prioritized over addressing barriers to healthcare access in the US. CONCLUSIONS: Inadequate access to healthcare is an issue in the US, particularly in rural areas. Rural healthcare consumers compose a hard-to-reach patient population. Too few providers exist to meet population health needs, and fragmented communication impairs rural health systems' ability to function. These issues exacerbate the difficulty of ensuring acceptable and appropriate delivery of healthcare services, which compound all other barriers to healthcare access for rural residents. Each dimension of access must be monitored to improve patient experiences and outcomes for rural Americans.
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Personal de Salud , Accesibilidad a los Servicios de Salud , Comunicación , Humanos , Investigación Cualitativa , Población Rural , Estados UnidosRESUMEN
Regulation of enzyme activity is vital for living organisms. In metalloenzymes, far-reaching rearrangements of the protein scaffold are generally required to tune the metal cofactor's properties by allosteric regulation. Here structural analysis of hydroxyketoacid aldolase from Sphingomonas wittichii RW1 (SwHKA) revealed a dynamic movement of the metal cofactor between two coordination spheres without protein scaffold rearrangements. In its resting state configuration (M2+ R ), the metal constitutes an integral part of the dimer interface within the overall hexameric assembly, but sterical constraints do not allow for substrate binding. Conversely, a second coordination sphere constitutes the catalytically active state (M2+ A ) at 2.4â Å distance. Bidentate coordination of a ketoacid substrate to M2+ A affords the overall lowest energy complex, which drives the transition from M2+ R to M2+ A . While not described earlier, this type of regulation may be widespread and largely overlooked due to low occupancy of some of its states in protein crystal structures.
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Metaloproteínas , Metaloproteínas/química , Metales , Fructosa-Bifosfato Aldolasa/metabolismo , Regulación AlostéricaRESUMEN
Background: Upregulation of the endocannabinoid enzyme fatty acid amide hydrolase (FAAH) has been linked to abnormal activity in frontoamygdalar circuits, a hallmark of posttraumatic stress disorder. We tested the hypothesis that FAAH levels in the amygdala were negatively correlated with functional connectivity between the amygdala and prefrontal cortex, subserving stress and affect control. Methods: Thirty-one healthy participants completed positron emission tomography (PET) imaging with the FAAH probe [C-11]CURB, and resting-state functional MRI scans. Participants were genotyped for the FAAH polymorphism rs324420, and trait neuroticism was assessed. We calculated amygdala functional connectivity using predetermined regions of interest (including the subgenual ventromedial prefrontal cortex [sgvmPFC] and the dorsal anterior cingulate cortex [dACC]) and a seed-to-voxel approach. We conducted correlation analyses on functional connectivity, with amygdala [C-11]CURB binding as a variable of interest. Results: The strength of amygdala functional connectivity with the sgvmPFC and dACC was negatively correlated with [C-11]CURB binding in the amygdala (sgvmPFC: r = -0.38, q = 0.04; dACC: r = -0.44; q = 0.03). Findings were partly replicated using the seed-to-voxel approach, which showed a cluster in the ventromedial prefrontal cortex, including voxels in the dACC but not the sgvmPFC (cluster-level, family-wise error rate corrected p < 0.05). Limitations: We did not replicate earlier findings of a relationship between an FAAH polymorphism (rs324420) and amygdala functional connectivity. Conclusion: Our data provide preliminary evidence that lower levels of FAAH in the amygdala relate to increased frontoamygdalar functional coupling. Our findings were consistent with the role of FAAH in regulating brain circuits that underlie fear and emotion processing in humans.
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Amidohidrolasas/metabolismo , Amígdala del Cerebelo/fisiología , Imagen por Resonancia Magnética , Tomografía de Emisión de Positrones , Adulto , Amígdala del Cerebelo/diagnóstico por imagen , Femenino , Voluntarios Sanos , Humanos , Masculino , Corteza Prefrontal/diagnóstico por imagen , Corteza Prefrontal/metabolismoRESUMEN
Bedaquiline (BDQ), an inhibitor of the mycobacterial F1Fo-ATP synthase, has revolutionized the antitubercular drug discovery program by defining energy metabolism as a potent new target space. Several studies have recently suggested that BDQ ultimately causes mycobacterial cell death through a phenomenon known as uncoupling. The biochemical basis underlying this, in BDQ, is unresolved and may represent a new pathway to the development of effective therapeutics. In this communication, we demonstrate that BDQ can inhibit ATP synthesis in Escherichia coli by functioning as a H+/K+ ionophore, causing transmembrane pH and potassium gradients to be equilibrated. Despite the apparent lack of a BDQ-binding site, incorporating the E. coli Fo subunit into liposomes enhanced the ionophoric activity of BDQ. We discuss the possibility that localization of BDQ at F1Fo-ATP synthases enables BDQ to create an uncoupled microenvironment, by antiporting H+/K+ Ionophoric properties may be desirable in high-affinity antimicrobials targeting integral membrane proteins.
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Adenosina Trifosfato/biosíntesis , Antituberculosos/farmacología , Diarilquinolinas/farmacología , Proteínas de Escherichia coli/metabolismo , Escherichia coli/metabolismo , Ionóforos/farmacología , ATPasas de Translocación de Protón/metabolismo , Concentración de Iones de HidrógenoRESUMEN
The ϵ subunit of ATP synthases has been proposed to regulate ATP hydrolysis in bacteria. Prevailing evidence supports the notion that when the ATP concentration falls below a certain threshold, the ϵ subunit changes its conformation from a non-inhibitory down-state to an extended up-state that then inhibits enzymatic ATP hydrolysis by binding to the catalytic domain. It has been demonstrated that the ϵ subunit from Bacillus PS3 is selective for ATP over other nucleotides, including GTP. In this study, the purine triphosphate selectivity is rationalized by using results from MD simulations and free energy calculations for the R103A/R115A mutant of the ϵ subunit from Bacillus PS3, which binds ATP more strongly than the wild-type protein. Our results are in good agreement with experimental data, and the elucidated molecular basis for selectivity could help to guide the design of novel GTP sensors.
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Bacillus/enzimología , ATPasas de Translocación de Protón/metabolismo , Purinas/metabolismo , Adenosina Trifosfato/química , Adenosina Trifosfato/metabolismo , Sitios de Unión , Simulación de Dinámica Molecular , Subunidades de Proteína , ATPasas de Translocación de Protón/química , Purinas/química , TermodinámicaRESUMEN
Wavelength-tunable, time-locked pairs of ultrafast pulses are crucial in modern-day time-resolved measurements. We demonstrate a simple means of generating configurable optical pulse sequences: sub-picosecond pulses are carved out from a continuous wave laser via pump-induced optical Kerr switching in 10 cm of a commercial single-mode fiber. By introducing dispersion to the pump, the near transform-limited switched pulse duration is tuned between 305-570 fs. Two- and four-pulse signal trains are also generated by adding birefringent α-BBO plates in the pump beam. These results highlight an ultrafast light source with intrinsic timing stability and pulse-to-pulse phase coherence, where pulse generation could be adapted to wavelengths ranging from ultraviolet to infrared.
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The aerobic thermoalkaliphile Caldalkalibacillus thermarum strain TA2.A1 is a member of a separate order of alkaliphilic bacteria closely related to the Bacillales order. Efforts to relate the genomic information of this evolutionary ancient organism to environmental adaptation have been thwarted by the inability to construct a complete genome. The existing draft genome is highly fragmented due to repetitive regions, and gaps between and over repetitive regions were unbridgeable. To address this, Oxford Nanopore Technology's MinION allowed us to span these repeats through long reads, with over 6000-fold coverage. This resulted in a single 3.34 Mb circular chromosome. The profile of transporters and central metabolism gives insight into why the organism prefers glutamate over sucrose as carbon source. We propose that the deamination of glutamate allows alkalization of the immediate environment, an excellent example of how an extremophile modulates environmental conditions to suit its own requirements. Curiously, plant-like hallmark electron transfer enzymes and transporters are found throughout the genome, such as a cytochrome b6c1 complex and a CO2-concentrating transporter. In addition, multiple self-splicing group II intron-encoded proteins closely aligning to those of a telomerase reverse transcriptase in Arabidopsis thaliana were revealed. Collectively, these features suggest an evolutionary relationship to plant life.
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Bacillaceae/genética , Bacillaceae/metabolismo , Genómica , Aerobiosis , Evolución Biológica , Secuencias Repetitivas de Ácidos NucleicosRESUMEN
The synthetic properties of the Thiamine diphosphate (ThDP)-dependent pyruvate dehydrogenase E1 subunit from Escherichia coli (EcPDH E1) was assessed for carboligation reactions with aliphatic ketoacids. Due to its role in metabolism, EcPDH E1 was previously characterised with respect to its biochemical properties, but it was never applied for synthetic purposes. Here, we show that EcPDH E1 is a promising biocatalyst for the production of chiral α-hydroxyketones. WT EcPDH E1 shows a 180-250-fold higher catalytic efficiency towards 2-oxobutyrate or pyruvate, respectively, in comparison to engineered transketolase variants from Geobacillus stearothermophilus (TKGST). Its broad active site cleft allows for the efficient conversion of both (R)- and (S)-configured α-hydroxyaldehydes, next to linear and branched aliphatic aldehydes as acceptor substrates under kinetically controlled conditions. The alternate, thermodynamically controlled self-reaction of aliphatic aldehydes was shown to be limited to low levels of conversion, which we propose to be due to their large hydration constants. Additionally, the thermodynamically controlled approach was demonstrated to suffer from a loss of stereoselectivity, which makes it unfeasible for aliphatic substrates.
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Proteínas de Escherichia coli/metabolismo , Escherichia coli/enzimología , Complejo Piruvato Deshidrogenasa/metabolismo , Tiamina Pirofosfato/metabolismo , Escherichia coli/genética , Geobacillus stearothermophilus/enzimología , Geobacillus stearothermophilus/genética , Especificidad por Sustrato , Tiamina Pirofosfato/genética , Transcetolasa/genética , Transcetolasa/metabolismoRESUMEN
Bradbury, DG, Landers, GJ, Benjanuvatra, N, and Goods, PS. Comparison of linear and reverse linear periodized programs with equated volume and intensity for endurance running performance. J Strength Cond Res 34(5): 1345-1353, 2020-This investigation examined the effectiveness of 2 periodization methods on endurance running performance. Thirty recreational runners (25.2 ± 7.4 years; 175.4 ± 8.1 cm; 69.0 ± 9.8 kg) were assigned to 3 groups based on preintervention test results: linear periodization group (LPG, n = 10), reverse linear periodization group (RPG, n = 10), and control group (CG, n = 10). The LPG and RPG completed 3 training sessions (2 supervised and 1 unsupervised) per week in two 6-week blocks. The LPG went through a high-volume training program while the RPG performed higher intensity, lower volume training in the initial block. Training volume and intensity was reversed in the second 6-week training block. All subjects completed pre-training (week 0), midpoint (week 7), and post-training (week 14) testing, which included anthropometric measurements (body mass and sum of 8 skinfolds), treadmill tests for running economy (RE) and V[Combining Dot Above]O2max, and a 5,000-m time trial (TT) on a 400-m grass track. Greater improvements in the 5,000-m TT were observed in the LPG (76.8 ± 55.8 seconds, p = 0.009, d = 1.27) and the RPG (112.8 ± 83.4 seconds, p = 0.002, d = 1.51) than the CG (3.6 ± 59 seconds). No significant differences were found between the LPG and RPG (p = 0.321, d = 0.51). No group differences were found for V[Combining Dot Above]O2peak (p = 0.955) or RE at 9 km·h (p = 0.329) or 11 km·h (p = 0.558), respectively. However, significant improvements were seen in these variables after training: V[Combining Dot Above]O2peak (p = 0.010), RE 9 km·h (p < 0.001), and RE 11 km·h (p = 0.004). These results do not support linear periodization or reverse linear periodization as a superior method; however, periodized training elicited greater improvements in endurance performance than nonperiodized training, highlighting the importance of planned training structure.
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Resistencia Física/fisiología , Carrera/fisiología , Adulto , Pesos y Medidas Corporales , Prueba de Esfuerzo , Femenino , Humanos , Masculino , Persona de Mediana Edad , Estado Nutricional , Consumo de Oxígeno , Adulto JovenRESUMEN
Type-II NADH:quinone oxidoreductases (NDH-2s) are an important element of microbial pathogen electron transport chains and an attractive drug target. Despite being widely studied, its mechanism and catalysis are still poorly understood in a hydrophobic membrane environment. A recent report for the Escherichia coli NDH-2 showed NADH oxidation in a solution-based assay but apparently showed the reverse reaction in electrochemical studies, calling into question the validity of the electrochemical approach. Here we report electrochemical catalysis in the well-studied NDH-2 from Caldalkalibacillus thermarum (CthNDH-2). In agreement with previous reports, we demonstrated CthNDH-2 NADH oxidation in a solution assay and electrochemical assays revealed a system artifact in the absence of quinone that was absent in a membrane system. However, in the presence of either immobilized quinone or mobile quinone in a membrane, NADH oxidation was observed as in solution-phase assays. This conclusively establishes surface-based electrochemistry as a viable approach for interrogating electron transfer chain drug targets.
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Bacillaceae/enzimología , Proteínas del Complejo de Cadena de Transporte de Electrón/metabolismo , NADH Deshidrogenasa/metabolismo , NAD/metabolismo , Benzoquinonas/metabolismo , Biocatálisis , Dominio Catalítico , Espectroscopía Dieléctrica , Electrodos , Transporte de Electrón , Cinética , Membrana Dobles de Lípidos/metabolismo , Vitamina K 3/metabolismoRESUMEN
The ability to generate mode-engineered single photons to interface with disparate quantum systems is of importance for building a quantum network. Here we report on the generation of a pulsed, heralded single photon source with a sub-GHz spectral bandwidth that couples to indium arsenide quantum dots centered at 942 nm. The source is built with a type-II PPKTP down-conversion crystal embedded in a semi-confocal optical cavity and pumped with a 76 MHz repetition rate pulsed laser to emit collinear, polarization-correlated photon pairs resonant with a single quantum dot. In order to demonstrate direct coupling, we use the mode-engineered cavity-SPDC single-photon source to resonantly excite an isolated single quantum dot.