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991.
Eleonora Chiri Chris Greening Rachael Lappan David W. Waite Thanavit Jirapanjawat Xiyang Dong Stefan K. Arndt Philipp A. Nauer 《The ISME journal》2020,14(11):2715
Termite mounds have recently been confirmed to mitigate approximately half of termite methane (CH4) emissions, but the aerobic CH4 oxidising bacteria (methanotrophs) responsible for this consumption have not been resolved. Here, we describe the abundance, composition and CH4 oxidation kinetics of the methanotroph communities in the mounds of three distinct termite species sampled from Northern Australia. Results from three independent methods employed show that methanotrophs are rare members of microbial communities in termite mounds, with a comparable abundance but distinct composition to those of adjoining soil samples. Across all mounds, the most abundant and prevalent methane monooxygenase sequences were affiliated with upland soil cluster α (USCα), with sequences homologous to Methylocystis and tropical upland soil cluster (TUSC) also detected. The reconstruction of a metagenome-assembled genome of a mound USCα representative highlighted the metabolic capabilities of this group of methanotrophs. The apparent Michaelis–Menten kinetics of CH4 oxidation in mounds were estimated from in situ reaction rates. Methane affinities of the communities were in the low micromolar range, which is one to two orders of magnitude higher than those of upland soils, but significantly lower than those measured in soils with a large CH4 source such as landfill cover soils. The rate constant of CH4 oxidation, as well as the porosity of the mound material, were significantly positively correlated with the abundance of methanotroph communities of termite mounds. We conclude that termite-derived CH4 emissions have selected for distinct methanotroph communities that are kinetically adapted to elevated CH4 concentrations. However, factors other than substrate concentration appear to limit methanotroph abundance and hence these bacteria only partially mitigate termite-derived CH4 emissions. Our results also highlight the predominant role of USCα in an environment with elevated CH4 concentrations and suggest a higher functional diversity within this group than previously recognised.Subject terms: Soil microbiology, Biogeochemistry 相似文献
992.
993.
Eleonora Cerasoli Sharon M Kelly John R Coggins Deborah J Boam David T Clarke Nicholas C Price 《European journal of biochemistry》2002,269(8):2124-2132
Shikimate kinase was chosen as a convenient representative example of the subclass of alpha/beta proteins with which to examine the mechanism of protein folding. In this paper we report on the refolding of the enzyme after denaturation in urea. As shown by the changes in secondary and tertiary structure monitored by far UV circular dichroism (CD) and fluorescence, respectively, the enzyme was fully unfolded in 4 m urea. From an analysis of the unfolding curve in terms of the two-state model, the stability of the folded state could be estimated as 17 kJ.mol-1. Approximately 95% of the enzyme activity could be recovered on dilution of the urea from 4 to 0.36 m. The results of spectroscopic studies indicated that refolding occurred in at least four kinetic phases, the slowest of which (k = 0.009 s-1) corresponded with the regain of shikimate binding and of enzyme activity. The two most rapid phases were associated with a substantial increase in the binding of 8-anilino-1-naphthalenesulfonic acid with only modest changes in the far UV CD, indicating that a collapsed intermediate with only partial native secondary structure was formed rapidly. The relevance of the results to the folding of other alpha/beta domain proteins is discussed. 相似文献
994.
Eleonora Olivetta Cinzia Mallozzi Vitalba Ruggieri Donatella Pietraforte Maurizio Federico Massimo Sanchez 《Journal of cellular biochemistry》2009,106(5):812-822
The Nef protein of the human immunodeficiency virus type 1 (HIV‐1) plays a crucial role in AIDS pathogenesis by modifying host cell signaling pathways. We investigated the effects of Nef on the NADPH oxidase complex, a key enzyme involved in the generation of reactive oxygen species during the respiratory burst in human monocyte/macrophages. We have recently shown that the inducible expression of HIV‐1 Nef in human macrophages cell line modulates in bi‐phasic mode the superoxide anion release by NADPH oxidase, inducing a fast increase of the superoxide production, followed by a delayed strong inhibition mediated by Nef‐induced soluble factor(s). Our study is focused on the molecular mechanisms involved in Nef‐mediated activation of NADPH oxidase and superoxide anion release. Using U937 cells stably transfected with different Nef alleles, we found that both Nef membrane localization and intact SH3‐binding domain are needed to induce superoxide release. The lack of effect during treatment with a specific MAPK pathway inhibitor, PD98059, demonstrated that Nef‐induced superoxide release is independent of Erk1/2 phosphorylation. Furthermore, Nef induced the phosphorylation and then the translocation of the cytosolic subunit of NADPH oxidase complex p47phox to the plasma membrane. Adding the inhibitor PP2 prevented this process, evidencing the involvement of the Src family kinases on Nef‐mediated NADPH oxidase activation. In addition, LY294002, a specific inhibitor of phosphoinositide 3‐kinase (PI3K) inhibited both the Nef‐induced p47phox phosphorylation and the superoxide anion release. These data indicate that Nef regulates the NADPH oxidase activity through the activation of the Src kinases and PI3K. J. Cell. Biochem. 106: 812–822, 2009. © 2009 Wiley‐Liss, Inc. 相似文献
995.
Pasquale Chieco Maura Pagnoni Eleonora Romagnoli Cinzia Melchiorri 《The Histochemical journal》1993,25(8):569-577
Summary Mitotic index is a clinically important parameter in cancer pathology. We developed a staining method using Toluidine Blue
to detect efficiently and rapidly mitotic figures in sections of formalin-fixed paraffin-embedded human and rat tisues. Sections
were stained at acid pH with a 0.01% Toluidine Blue solution after removal of RNA with hydrochloric acid or ribonuclease.
The optimal pH of the TB staining solution was found to be 4.5 for rat tissues and 3.5 for human tissues. This procedure stained
mitotic figures much more intensely than other (extra)cellular structures. A quantitative estimate of the total number of
nuclei in the field where mitotic figures were counted, was obtained in an adjacent section hydrolysed in 5 N hydrochloric
acid and stained by the Feulgen reaction with a Schiff-type reagent containing 0.01% Toluidine Blue. This method specifically
stained interphase and mitotic nuclei and the field cellularity could be quantified by image cytometry. When these procedures
were performed on two consecutive serial sections, a mitotic index could be determined accurately by relating the count of
mitotic figures to the number of tumour cells. 相似文献
996.
Diversity of inorganic arsenite biotransformation 总被引:2,自引:0,他引:2
Sheila M. Healy Eric Wildfang Robert A. Zakharyan H. Vasken Aposhian 《Biological trace element research》1999,68(3):249-266
Biotransformation of inorganic arsenic in mammals is catalyzed by three serial enzyme activities: arsenate reductase, arsenite
methyltransferase, and monomethylarsonate methyltransferase. Our laboratory has purified and characterized these enzymes in
order to understand the mechanisms and elucidate the variations of the responses to arsenate /arsenite challenge. Our results
indicate a marked deficiency and diversity of these enzyme activities in various animal species. 相似文献
997.
998.
Leonardo Potenza Patrizia Barozzi Daniela Vallerini Eleonora Zanetti Giuseppe Torelli Mario Luppi 《Current fungal infection reports》2009,3(4):216-222
The expansion of the antifungal armamentarium and the implementation of imaging techniques and new nonculture-based fungal
diagnostics (NCBFDs) have improved the survival of patients with invasive asper-gillosis (IA). However, mortality rates still
remain high, possibly influenced by several pitfalls, affecting NCBFDs and reducing the window of opportunity for earlier
treatment. A large body of in vitro and in vivo studies has demonstrated that several fungal proteic components are strongly
immunogenic, and both the adaptive immunity and the innate branch are heavily involved in the recognition and clearance of
fungal pathogens, resulting, on occasion, in a useful tool for the treatment of IA. By evaluating these studies, this review
considers the possibility of exploiting either components of the innate or adaptive immunity to support the rapid and early
diagnosis of IA. 相似文献
999.
Lauren J. Green Stephen H. Kennedy Lucy Mackillop Stephen Gerry Manorama Purwar Eleonora Staines Urias Leila Cheikh Ismail Fernando Barros Cesar Victora Maria Carvalho Eric Ohuma Yasmin Jaffer J. Alison Noble Michael Gravett Ruyan Pang Ann Lambert Enrico Bertino Aris T. Papageorghiou Cutberto Garza Zulfiqar Bhutta Jos Villar Peter Watkinson for the International Fetal Newborn Growth Consortium for the st Century 《PLoS medicine》2021,18(4)
BackgroundGestational hypertensive and acute hypotensive disorders are associated with maternal morbidity and mortality worldwide. However, physiological blood pressure changes in pregnancy are insufficiently defined. We describe blood pressure changes across healthy pregnancies from the International Fetal and Newborn Growth Consortium for the 21st Century (INTERGROWTH-21st) Fetal Growth Longitudinal Study (FGLS) to produce international, gestational age-specific, smoothed centiles (third, 10th, 50th, 90th, and 97th) for blood pressure.Methods and findingsSecondary analysis of a prospective, longitudinal, observational cohort study (2009 to 2016) was conducted across 8 diverse urban areas in Brazil, China, India, Italy, Kenya, Oman, the United Kingdom, and the United States of America. We enrolled healthy women at low risk of pregnancy complications. We measured blood pressure using standardised methodology and validated equipment at enrolment at <14 weeks, then every 5 ± 1 weeks until delivery.We enrolled 4,607 (35%) women of 13,108 screened. The mean maternal age was 28·4 (standard deviation [SD] 3.9) years; 97% (4,204/4,321) of women were married or living with a partner, and 68% (2,955/4,321) were nulliparous. Their mean body mass index (BMI) was 23.3 (SD 3.0) kg/m2. Systolic blood pressure was lowest at 12 weeks: Median was 111.5 (95% CI 111.3 to 111.8) mmHg, rising to a median maximum of 119.6 (95% CI 118.9 to 120.3) mmHg at 40 weeks’ gestation, a difference of 8.1 (95% CI 7.4 to 8.8) mmHg. Median diastolic blood pressure decreased from 12 weeks: 69.1 (95% CI 68.9 to 69.3) mmHg to a minimum of 68.5 (95% CI 68.3 to 68.7) mmHg at 19+5 weeks’ gestation, a change of −0·6 (95% CI −0.8 to −0.4) mmHg. Diastolic blood pressure subsequently increased to a maximum of 76.3 (95% CI 75.9 to 76.8) mmHg at 40 weeks’ gestation. Systolic blood pressure fell by >14 mmHg or diastolic blood pressure by >11 mmHg in fewer than 10% of women at any gestational age. Fewer than 10% of women increased their systolic blood pressure by >24 mmHg or diastolic blood pressure by >18 mmHg at any gestational age. The study’s main limitations were the unavailability of prepregnancy blood pressure values and inability to explore circadian effects because time of day was not recorded for the blood pressure measurements.ConclusionsOur findings provide international, gestational age-specific centiles and limits of acceptable change to facilitate earlier recognition of deteriorating health in pregnant women. These centiles challenge the idea of a clinically significant midpregnancy drop in blood pressure.Lauren Green and colleagues study blood pressure in pregnant women across a range of countries. 相似文献
1000.
Ibtisam Salim Eleonora Staines-Urias Sam Mathewlynn Lior Drukker Manu Vatish Lawrence Impey 《PLoS medicine》2021,18(1)
BackgroundBreech presentation at term contributes significantly to cesarean section (CS) rates worldwide. External cephalic version (ECV) is a safe procedure that reduces term breech presentation and associated CS. A principal barrier to ECV is failure to diagnose breech presentation. Failure to diagnose breech presentation also leads to emergency CS or unplanned vaginal breech birth. Recent evidence suggests that undiagnosed breech might be eliminated using a third trimester scan. Our aim was to evaluate the impact of introducing a routine 36-week scan on the incidence of breech presentation and of undiagnosed breech presentation.Methods and findingsWe carried out a population-based cohort study of pregnant women in a single unit covering Oxfordshire, United Kingdom. All women delivering between 37+0 and 42+6 weeks gestational age, with a singleton, nonanomalous fetus over a 4-year period (01 October 2014 to 30 September 2018) were included. The mean maternal age was 31 years, mean BMI 26, 44% were nulliparous, and 21% were of non-white ethnicity. Comparisons between the 2 years before and after introduction of routine 36-week scan were made for 2 primary outcomes of (1) the incidence of breech presentation and (2) undiagnosed breech presentation. Secondary outcomes related to ECV, mode of birth, and perinatal outcomes. Relative risks (RRs) with 95% confidence intervals (CIs) are reported. A total of 27,825 pregnancies were analysed (14,444 before and 13,381 after). A scan after 35+0 weeks was performed in 5,578 (38.6%) before, and 13,251 (99.0%) after (p < 0.001). The incidence of breech presentation at birth did not change significantly (2.6% and 2.7%) (RR 1.02; 95% CI 0.89, 1.18; p = 0.76). The rate of undiagnosed breech before labour reduced, from 22.3% to 4.7% (RR 0.21; 95% CI 0.12, 0.36; p < 0.001). Vaginal breech birth rates fell from 10.3% to 5.3% (RR 0.51; 95% CI 0.30, 0.87; p = 0.01); nonsignificant increases in elective CS rates and decreases in emergency CS rates for breech babies were seen. Neonatal outcomes were not significantly altered. Study limitations include insufficient numbers to detect serious adverse outcomes, that we cannot exclude secular changes over time which may have influenced our results, and that these findings are most applicable where a comprehensive ECV service exists.ConclusionsIn this study, a universal 36-week scan policy was associated with a reduction in the incidence but not elimination of undiagnosed term breech presentation. There was no reduction in the incidence of breech presentation at birth, despite a comprehensive ECV service.Ibtisam Salim and co-workers report on incidence of breech presentation in pregnant women receiving a 36-week scan. 相似文献