337 MITOCHONDRIA AND REACTIVE OXYGEN SPECIES IN PREBUPERTAL LAMB OOCYTES BEFORE AND AFTER IN VITRO MATURATION

2010 ◽  
Vol 22 (1) ◽  
pp. 325
Author(s):  
M. E. Dell'Aquila ◽  
B. Ambruosi ◽  
R. Guastamacchia ◽  
F. Binetti ◽  
E. Ciani ◽  
...  
Keyword(s):  
Reactive Oxygen Species ◽  
Reactive Oxygen ◽  
Female Reproductive Tract ◽  
Nuclear Chromatin ◽  
Oxygen Species ◽  
Intracellular Ros ◽  
Before And After ◽  
Group A ◽  
Group B

Juvenile in vitro embryo transfer (JIVET) reduces the generation interval and increases the rate of genetic gain. The developmental competence of in vitro-produced embryos is strictly related to oocyte quality. Oxidative stress in the oocyte is an emerging problem in reproductive in vitro technologies, due to the gas atmosphere used to incubate oocytes and the lack of physiological defense mechanisms available in the female reproductive tract. The major source of reactive oxygen species (ROS) is represented by mitochondria where ROS are produced during oxidative phosphorylation. The aim of the present study was to analyze mitochondria and ROS in ovine prepubertal oocytes before and after IVM in order to clarify their suitability in JIVET programs. Cumulus-oocyte complexes from the ovaries of 38 slaughtered prepubertal (less than 8 months of age) lambs of the Comisana breed were analyzed at retrieval (group A) or after IVM (group B; Ambruosi et al. 2009 Theriogenology 71, 1093-1104). After cumulus cell removal, all oocytes underwent nuclear chromatin, mitochondria and ROS evaluation by confocal analysis of fluorescence distribution and intensity. Hoechst 33258 and Mitotracker Orange CMTM Ros (Molecular Probes Inc., Eugene, OR) were used to label nuclear chromatin and mitochondria (Ambruosi et al. 2009) and 2′,7′-dichloro-dihydro-fluorescein diacetate was used for ROS labelling (Hashimoto et al. 2000 Mol. Reprod. Dev. 57, 353-360). Out of 65 oocytes from group A, 38 oocytes with regular size (>130 μm in diameter), morphology and nuclear chromatin at the GV stage were selected for analysis. One-hundred-thirty-eight oocytes underwent IVM (group B). Nuclear maturation rate (metaphase II with 1st polar body extruded) was 54%, 75/138. All MII oocytes were used for analysis. Significantly higher rate of oocytes from group B showed heterogeneous (large aggregates, clusters, pericortical, perinuclear) mitochondrial (mt) distribution pattern than oocytes from group A (55%, 41/75 v. 29%, 11/38, respectively; P < 0.05) which showed uniform distribution of small mt aggregates. Fluorescent intensity of mt labeling did not differ between groups (43.05 ± 16.15 v. 45.89 ± 10.36, for group A and B respectively; NS). In most of the oocytes from both groups, intracellular ROS were distributed in small or large aggregates (35/38, 92% and 62/75, 83%). No statistical difference was observed for intracellular ROS levels between oocytes from group A (66.36 ± 13.2) and group B (72.84 ± 20.63; NS). The culture conditions used in this study provided normal mt distribution and intracellular ROS levels. Qualitative and quantitative evaluation of mitochondria and intracellular ROS could be useful to improve in vitro culture methods in ovine prepubertal oocytes.

270 MITOCHONDRIA AND REACTIVE OXYGEN SPECIES COLOCALIZATION IN IN VIVO AND IN VITRO MATURED OOCYTES FROM SUPEROVULATED ADULT EWES

2011 ◽  
Vol 23 (1) ◽  
pp. 233
Author(s):  
B. Ambruosi ◽  
N. A. Martino ◽  
M. Filioli Uranio ◽  
F. Silvestre ◽  
F. Binetti ◽  
...  
Keyword(s):  
Reactive Oxygen Species ◽  
Cumulus Cell ◽  
Reactive Oxygen ◽  
Oocyte Quality ◽  
Nuclear Chromatin ◽  
Oxygen Species ◽  
Fluorescent Intensity ◽  
Intracellular Ros

Analyses of energy and redox status parameters are emerging technologies to improve oocyte quality assessment. Mitochondria (mt) play a vital role in the oocyte to support maturation, fertilization, and pre-implantation development. They are the major source of reactive oxygen species (ROS) produced during oxidative phosphorylation, which are not only by-products of cell metabolism but also important molecules for regulation of intracellular cell signaling. The aim of the present study was to test for mt/ROS colocalization in oocytes recovered from superovulated adult ewes and examined after in vivo or in vitro maturation (IVM). Cumulus–oocyte complexes of 8 superovulated (fluorogestone acetate + D-cloprostenol for oestrus synchronization, pFSH/pLH and eCG for superovulation) adult (2 to 8 years of age) ewes were recovered (ovariohysterectomy by midventral laparotomy performed 54 h after vaginal sponge removal) either from flushing oviducts (oviducal oocytes) or from ovarian growing follicles (1–5 mm in diameter; follicular oocytes). Follicular oocytes were analysed after IVM (Ambruosi et al. 2009 Theriogenology 71, 1093–1104). After cumulus cell removal, all oocytes underwent nuclear chromatin, mt, and ROS evaluation. Hoechst 33258 and Mitotracker Orange CMTM Ros were used to label nuclear chromatin and mt (Ambruosi et al. 2009) and 2′,7′-dichloro-dihydro-fluorescein diacetate was used for ROS labelling (Hashimoto et al. 2000 Mol. Reprod. Dev. 57, 353–360). Oocytes at the metaphase II (MII) stage showing regular ooplasmic size (>130 μm in diameter) and morphology were selected for confocal analysis of mt/ROS fluorescence distribution, intensity, and colocalization. Forty oviducal MII oocytes recovered from 8 ewes were analysed. Thirty-two oocytes recovered from the ovaries of 4 ewes underwent IVM, and 23 out of 32 (72%) reached nuclear maturation and were analysed. The rate of oocytes showing perinuclear mt distribution pattern did not differ between oviducal and IVM oocytes (33%, 13/40 v. 43%, 10/23; not significant). In these oocytes, fluorescent intensity of mt labelling and intracellular ROS levels did not differ between oviducal and IVM ooocytes (996.27 ± 363.57 v. 798.13 ± 275.91; not significant; and 1808.11 ± 442.78 v. 1473.29 ± 662.49, for mt and ROS, respectively; not significant), whereas mt/ROS colocalization was significantly higher in ovulated oocytes than in IVM oocytes (Pearson coefficient 0.67 ± 0.11 v. 0.39 ± 0.19, respectively; P < 0.001). In conclusion, in oocytes of adult ewes, mt aggregation, apparent energy status, and intracellular ROS levels do not differ between ovulated and IVM oocytes, but mt/ROS colocalization differs between the 2 groups. As it was reported for other cell systems that such a difference can be indicative of healthy status of ovulated oocytes, we suggest that mt/ROS colocalization could be considered as a suitable marker of oocyte quality. Financial support was provided by Fondazione Cassa di Risparmio di Puglia 2008. Project: Salvaguardia di razze ovine autoctone pugliesi (R.U. DPA Resp. Sci. Prof. M. E. DellAquila).

scholarly journals Selection of theIn VitroCulture Media Influences mRNA Expression of Hedgehog Genes,Il-6,and Important Genes regarding Reactive Oxygen Species in Single Murine Preimplantation Embryos

2012 ◽  
Vol 2012 ◽  
pp. 1-8 ◽  
Author(s):  
N. Pfeifer ◽  
D. M. Baston-Büst ◽  
J. Hirchenhain ◽  
U. Friebe-Hoffmann ◽  
D. T. Rein ◽  
...  
Keyword(s):  
Reactive Oxygen Species ◽  
Mrna Expression ◽  
Culture Media ◽  
Expression Profiles ◽  
Reactive Oxygen ◽  
Female Reproductive Tract ◽  
Preimplantation Embryos ◽  
Oxygen Species

Background. The aim of this paper was to determine the influence of differentin vitroculture media on mRNA expression of Hedgehog genes,il-6,and important genes regarding reactive oxygen species in single mouse embryos.Methods. Reverse transcription of single embryos either culturedin vitrofrom day 0.5 until 3.5 (COOK’s Cleavage medium or Vitrolife’s G-1 PLUS medium) orin vivountil day 3.5post coitum. PCR was carried out forβ-actinfollowed by nested-PCR forshh, ihh, il-6, nox, gpx4, gpx1,andprdx2.Results. The number of murine blastocysts cultured in COOK medium which expressedil-6, gpx4, gpx1,andprdx2mRNA differed significantly compared to thein vivogroup. Except fornox, the mRNA profile of the Vitrolife media group embryos varied significantly from thein vivoones regarding the number of blastocysts expressing the mRNA ofshh, ihh, il-6, gpx4, gpx1andprdx2.Conclusions. The present study shows that differentin vitroculture media lead to different mRNA expression profiles during early development. Even the newly developedin vitroculture media are not able to mimic the female reproductive tract. The question of long-term consequences for children due to assisted reproduction techniques needs to be addressed in larger studies.

Reduced levels of intracellular reactive oxygen species and apoptotic status are not correlated with increases in cryotolerance of bovine embryos produced in vitro in the presence of antioxidants

2014 ◽  
Vol 26 (6) ◽  
pp. 797 ◽  
Author(s):  
Nathália A. S. Rocha-Frigoni ◽  
Beatriz C. S. Leão ◽  
Ériklis Nogueira ◽  
Mônica F. Accorsi ◽  
Gisele Z. Mingoti
Keyword(s):  
Reactive Oxygen Species ◽  
Reactive Oxygen ◽  
Intracellular Reactive Oxygen Species ◽  
Control Group ◽  
Bovine Embryo ◽  
Oxygen Species ◽  
Antioxidant Supplementation ◽  
In Vitro Production ◽  
Intracellular Ros

The effects of intracellular (cysteine and β-mercaptoethanol) and extracellular (catalase) antioxidant supplementation at different times during in vitro production (IVM and/or in vitro culture (IVC)) on bovine embryo development, intracellular reactive oxygen species (ROS) levels, apoptosis and re-expansion rates after a vitrification–thawing process were examined. Blastocyst frequencies were not affected by either antioxidant supplementation (40.5%–56.4%) or the timing of supplementation (41.7%–55.4%) compared with control (48.7%; P > 0.05). Similarly, antioxidants and the moment of supplementation did not affect (P > 0.05) the total number of blastomeres (86.2–90.5 and 84.4–90.5, respectively) compared with control (85.7). However, the percentage of apoptotic cells was reduced (P < 0.05) in groups supplemented during IVM (1.7%), IVC (2.0%) or both (1.8%) compared with control (4.3%). Intracellular ROS levels measured in Day 7 blastocysts were reduced (P < 0.05) in all groups (0.60–0.78), with the exception of the group supplemented with β-mercaptoethanol during IVC (0.88), which did not differ (P > 0.05) from that in the control group (1.00). Re-expansion rates were not affected (P > 0.05) by the treatments (50.0%–93.0%). In conclusion, antioxidant supplementation during IVM and/or IVC reduces intracellular ROS and the rate of apoptosis; however, supplementation does not increase embryonic development and survival after vitrification.

The early embryo response to intracellular reactive oxygen species is developmentally regulated

2011 ◽  
Vol 23 (4) ◽  
pp. 561 ◽  
Author(s):  
Nathan T. Bain ◽  
Pavneesh Madan ◽  
Dean H. Betts
Keyword(s):  
Reactive Oxygen Species ◽  
Ex Vivo ◽  
Reactive Oxygen ◽  
Dependent Manner ◽  
Oxygen Species ◽  
Blastocyst Development ◽  
Developmentally Regulated ◽  
H2o2 Treatment ◽  
Intracellular Ros

In vitro embryo production (IVP) suffers from excessive developmental failure. Its inefficiency is linked, in part, to reactive oxygen species (ROS) brought on by high ex vivo oxygen (O2) tensions. To further delineate the effects of ROS on IVP, the intracellular ROS levels of early bovine embryos were modulated by: (1) varying O2 tension; (2) exogenous H2O2 treatment; and (3) antioxidant supplementation. Although O2 tension did not significantly affect blastocyst frequencies (P > 0.05), 20% O2 accelerated the rate of first cleavage division and significantly decreased and increased the proportion of permanently arrested 2- to 4-cell embryos and apoptotic 9- to 16-cell embryos, respectively, compared with embryos cultured in 5% O2 tension. Treatment with H2O2, when applied separately to oocytes, zygotes, 2- to 4-cell embryos or 9- to 16-cell embryos, resulted in a significant (P < 0.05) dose-dependent decrease in blastocyst development in conjunction with a corresponding increase in the induction of either permanent embryo arrest or apoptosis in a stage-dependent manner. Polyethylene glycol–catalase supplementation reduced ROS-induced embryo arrest and/or death, resulting in a significant (P < 0.05) increase in blastocyst frequencies under high O2 culture conditions. Together, these results indicate that intracellular ROS may be signalling molecules that, outside an optimal range, result in various developmentally regulated modes of embryo demise.

Iron-induced reactive oxygen species mediate transporter DMT1 endocytosis and iron uptake in intestinal epithelial cells

2015 ◽  
Vol 309 (8) ◽  
pp. C558-C567 ◽  
Author(s):  
Andrés Esparza ◽  
Ziomara P. Gerdtzen ◽  
Alvaro Olivera-Nappa ◽  
J. Cristian Salgado ◽  
Marco T. Núñez
Keyword(s):  
Reactive Oxygen Species ◽  
Iron Uptake ◽  
Apical Membrane ◽  
Reactive Oxygen ◽  
Surface Protein ◽  
Radical Scavenger ◽  
Oxygen Species ◽  
Intestinal Epithelial ◽  
Intracellular Ros ◽  
Before And After

Recent evidence shows that iron induces the endocytosis of the iron transporter dimetal transporter 1 (DMT1) during intestinal absorption. We, and others, have proposed that iron-induced DMT1 internalization underlies the mucosal block phenomena, a regulatory response that downregulates intestinal iron uptake after a large oral dose of iron. In this work, we investigated the participation of reactive oxygen species (ROS) in the establishment of this response. By means of selective surface protein biotinylation of polarized Caco-2 cells, we determined the kinetics of DMT1 internalization from the apical membrane after an iron challenge. The initial decrease in DMT1 levels in the apical membrane induced by iron was followed at later times by increased levels of DMT1. Addition of Fe2+, but not of Cd2+, Zn2+, Cu2+, or Cu1+, induced the production of intracellular ROS, as detected by 2′,7′-dichlorofluorescein (DCF) fluorescence. Preincubation with the antioxidant N-acetyl-l-cysteine (NAC) resulted in increased DMT1 at the apical membrane before and after addition of iron. Similarly, preincubation with the hydroxyl radical scavenger dimethyl sulfoxide (DMSO) resulted in the enhanced presence of DMT1 at the apical membrane. The decrease of DMT1 levels at the apical membrane induced by iron was associated with decreased iron uptake rates. A kinetic mathematical model based on operational rate constants of DMT1 endocytosis and exocytosis is proposed. The model qualitatively captures the experimental observations and accurately describes the effect of iron, NAC, and DMSO on the apical distribution of DMT1. Taken together, our data suggest that iron uptake induces the production of ROS, which modify DMT1 endocytic cycling, thus changing the iron transport activity at the apical membrane.

scholarly journals Differential expression pattern of genes involved in oxygen metabolism in epithelial oviductal cells during primary in vitro culture

2019 ◽  
Vol 7 (2) ◽  
pp. 66-76
Author(s):  
Katarzyna Stefańska ◽  
Sandra Knap ◽  
Magdalena Kulus ◽  
Ievgenia Kocherova ◽  
Piotr Celichowski ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Reactive Oxygen Species ◽  
Epithelial Cells ◽  
In Vitro Culture ◽  
Cellular Response ◽  
Reactive Oxygen ◽  
Oxygen Metabolism ◽  
Female Reproductive Tract ◽  
Oxygen Species

AbstractOxygen metabolism is crucial in establishing successful pregnancy, since excessive amount of reactive oxygen species (ROS) may exert deleterious effects on the developing embryo. There are several defense mechanisms against oxidative stress in the female reproductive tract, including production of antioxidant enzymes by oviductal epithelial cells (OECs). Undoubtedly, OECs play major part in female fertility and may also serve as an in vitro model of the oviduct. Therefore, the aim of this study was to investigate the expression of genes involved in oxygen metabolism. We have isolated OECs from oviducts of crossbred gilts (n=45) and maintained their in vitro culture for 30 days, collecting their RNA at days 1, 7, 15 and 30. The gene expression was determined with the use of Affymetrix® Porcine Gene 1.1 ST Array Strip. Our results revealed 166 differentially expressed genes belonging to four ontology groups: „cellular response to oxidative stress”, “cellular response to oxygen-containing compound”, “cellular response to oxygen levels” and “cellular response to reactive oxygen species”, most of which are also involved in other major processes in the organism. However, our findings provide a valuable insight into porcine reproductive biology and may be utilized in optimization of assisted reproduction techniques.Running title: Genes involved in oxygen metabolism in oviductal epithelial cells

90 INTRACELLULAR REACTIVE OXYGEN SPECIES IN BOVINE EMBRYOS CULTURED IN VITRO WITH CATALASE UNDER VARIOUS OXYGEN TENSIONS

2012 ◽  
Vol 24 (1) ◽  
pp. 157 ◽  
Author(s):  
N. A. S. Rocha ◽  
B. C. S. Leão ◽  
M. F. Accorsi ◽  
G. Z. Mingoti
Keyword(s):  
Oxidative Stress ◽  
Reactive Oxygen Species ◽  
Embryonic Development ◽  
Embryo Development ◽  
Reactive Oxygen ◽  
Oxygen Species ◽  
Bovine Embryos ◽  
Intracellular Ros ◽  
Oxygen Tensions

The production of reactive oxygen species (ROS), such as superoxide anion (O2–), hydroxyl radical (OH–) hydrogen peroxide (H2O2) and organic peroxides, is a normal process that occurs in the cellular mitochondrial respiratory chain. The high oxygen tension in in vitro culture (IVC) conditions is believed to induce oxidative stress, as a result of increase in ROS intracellular production, that can be correlated with embryonic developmental failure. Supplementation with antioxidants during IVC appears to increase the resistance of bovine embryos to the oxidative stress and consequently improve embryo development. The aim of this study was to evaluate the effects of antioxidant (catalase) and oxygen tensions during IVC on the embryonic development and quantification of intracellular ROS. Cumulus–oocyte complexes (COC; n = 337) were in vitro matured (IVM) in TCM-199 supplemented with 0.2 mM pyruvate, 25 mM sodium bicarbonate, 75 μg mL–1 gentamicin, 10% FCS and hormones for 24 h at 38.5°C and 5% CO2 in air. Then they were fertilized and the presumptive zygotes were cultured in SOFaa medium without (control) or with 100 UI catalase (CAT) for 7 days at 38.5°C in one of 2 types of humified atmosphere: 5% CO2 in air (≈20% O2) or in gaseous mixture (7% O2, 5% CO2 and 88% N2). The cleavage rate was evaluated at 72 hours post-insemination (hpi) and the embryonic development at 168 hpi. At this time, the level of intracellular ROS was measured using the fluorescent probe 6-carboxy-2′,7′-dichlorodihydrofluorescein diacetate (H2DCFDA; Molecular Probes, Invitrogen, Oakville, Canada), at 5 μM (Bain et al. 2011 Reprod. Fertil. Dev. 23, 561–575). Stained embryos were imaged immediately using an inverted microscope and analysed by Q-Capture Pro image software (QImaging, Surrey, BC, Canada). The signal intensity values of embryos were subtracted by the average of backgrounds in the images. Embryo development was analysed by chi-squared test and means of the intensity of fluorescence were compared by ANOVA followed by Tukey's test (P < 0.05). The cleavage rates were 84.04%a (control 20% O2), 77.55%a (CAT 20% O2), 77.03%a (control 7% O2) and 71.83%a (CAT 7% O2). The embryonic development rates were 40.43%a (control 20% O2), 33.67%a (CAT 20% O2), 20.27%b (control 7% O2) and 16.90%b (CAT 7% O2). The fluorescent intensity were 3.9 ± 0.4a (control 20% O2), 1.8 ± 0.2b (CAT 20% O2), 2.7 ± 0.2ab (control 7% O2) and 2.8 ± 0.2ab (CAT 7% O2). Although catalase did not significantly affect blastocyst frequencies (P > 0.05), embryo development was adversely affected by reduced O2 tension (P < 0.05). H2DCFDA staining indicated a significant (P < 0.05) reduction in the levels of intracellular ROS within embryos cultured with catalase under 20% O2 compared with the control group in the same O2 tension. Additionally, a consistent but insignificant reduction in intracellular ROS within embryos cultured under 7% O2 was found. We can conclude that supplementation with catalase to IVC medium at 20% O2 is suitable for lowering intracellular ROS levels in IVP bovine embryos, without lowering the rates of blastocysts production. This finding corroborates with theory that antioxidants are beneficial to embryo quality. Alta Genetics Brazil, Deoxi Biotecnologia.

scholarly journals Propolis, a Constituent of Honey, Inhibits the Development of Sugar Cataracts and High-Glucose-Induced Reactive Oxygen Species in Rat Lenses

2016 ◽  
Vol 2016 ◽  
pp. 1-6 ◽  
Author(s):  
Teppei Shibata ◽  
Shinsuke Shibata ◽  
Naoko Shibata ◽  
Etsuko Kiyokawa ◽  
Hiroshi Sasaki ◽  
...  
Keyword(s):  
Reactive Oxygen Species ◽  
Cell Death ◽  
Cell Viability ◽  
High Glucose ◽  
Reactive Oxygen ◽  
Oxygen Species ◽  
Histochemical Analysis ◽  
Intracellular Ros ◽  
Sugar Cataract

Purpose.This study investigated the effects of oral propolis on the progression of galactose-induced sugar cataracts in rats and thein vitroeffects of propolis on high-glucose-induced reactive oxygen species (ROS) and cell death in cultured rat lens cells (RLECs).Methods. Galactose-fed rats and RLECs cultured in high glucose (55 mM) medium were treated with propolis or vehicle control. Relative lens opacity was assessed by densitometry and changes in lens morphology by histochemical analysis. Intracellular ROS levels and cell viability were measured.Results. Oral administration of propolis significantly inhibited the onset and progression of cataract in 15% and 25% of galactose-fed rats, respectively. RLECs cultured with high glucose showed a significant increase in ROS expression with reduced cell viability. Treatment of these RLECs with 5 and 50 μg/mL propolis cultured significantly reduced ROS levels and increased cell viability, indicating that the antioxidant activity of propolis protected cells against ROS-induced damage.Conclusion. Propolis significantly inhibited the onset and progression of sugar cataract in rats and mitigated high-glucose-induced ROS production and cell death. These effects may be associated with the ability of propolis to inhibit hyperglycemia-evoked oxidative or osmotic stress-induced cellular insults.

scholarly journals The extracellular reactive oxygen species levels in primary in vitro culture of human ovarian granulosa and cumulus cells

2020 ◽  
Vol 8 (3) ◽  
pp. 112-117
Author(s):  
Ievgeniia Kocherova ◽  
Rut Bryl ◽  
Igor Crha ◽  
Pavel Ventruba ◽  
Jana Zakova ◽  
...  
Keyword(s):  
Reactive Oxygen Species ◽  
Primary Culture ◽  
Atmospheric Oxygen ◽  
Ovarian Follicle ◽  
Reactive Oxygen ◽  
Cumulus Cells ◽  
Oxygen Metabolism ◽  
Female Reproductive Tract ◽  
Oxygen Species

AbstractIn the female reproductive tract, reactive oxygen species (ROS) may exert physiological and pathophysio-logical effects. Although ROS play an essential role as the signaling molecules, their excessive accumulation contributes to the pathogenesis of many reproductive processes. In the ovarian follicle, ROS affect multiple physiological processes, including oocyte maturation and fertilization. However, a lack of studies showing to which extend ovarian granulosa and cumulus cells can contribute to the development of oxidative stress within the ovarian follicle. In the presented research, the extracellular ROS accumulation level was investigated using GCs and CCs primary in vitro cultures. The obtained results demonstrated a steady decrease in extracellular ROS level during GCs primary culture. By contrast, ROS concentration in CCs conditioned medium increased gradually between the first and the seventh days of culture. The observed changes may reflect the proliferation status and metabolic activity of GCs and CCs during in vitro culture. Additionally, the elevated ROS level at respective points of time could occur as a consequence of culture in atmospheric oxygen. The distinct function and localization within the ovarian follicle may explain the differences between GCs and CCs oxygen metabolism.Running title: Reactive oxygen species in primary culture of human follicular cells

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