57 research outputs found

    Endangered species Conservation in peri-urban habitats. Study of Yellow-bellied Toads Populations (Bombina variegata) in Geneva (Switzerland) - Ethological, Ecological and Genetic Approaches

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    Our planet is strongly suffering from human activities and their consequences. Obviously, the animals and plants have to cope with the variable environmental conditions that result from these anthropic activities. The aquatic species are even more vulnerable as, often, their habitats is affected by climate. As global warming causes the temperature to rise, the increase of evaporation and consequent dryness of ponds can highly affect the survival and fitness of their inhabitants. The amphibians are the mostly threatened vertebrate group, and the Yellow-bellied toad (Bombina variegata) is one of the most endangered amphibian species in Switzerland. In an effort to improve the knowledge on Bombina variegata in Geneva to develop more efficient and robust conservation measures, we monitored 27 sites (21 Genevan and 6 French) during 1 to 5 years using capture-recapture method. In these sites, we monitored 2713 ponds of three different categories: artificial ponds (n=1302), semi-natural ponds (n=1147) and natural ponds (n=264). The first category concerns plastic buckets that were installed in the field. The second category concerns artificial ponds that were dug in the field and made waterproof thanks to clay, or other ancient man-made ponds. The last category concerns natural depressions that were mapped in each site. The sites were monitored at least once a month during the activity period of the toads, for at least one year, but the prospections were much more regular in some sites (TEP: up to 21 sessions during a year, 5 years of monitoring). This census allowed the global observation (sum of capture events) of 2655 toads from 2012 to 2016 in the whole Geneva area. These represent 1587 adults (975 males, 612 females), 737 subadults (444 males, 293 females) and 331 juveniles (52 males, 70 females and 209 not sexed). Among these observations, we were able to recognize 1107 different individuals thanks to the colouration of their belly. We were also able to count 4770 tadpoles and 7819 eggs. The global sex-ratio on the whole study area is 53:47. The observed population size per site range from 2 to 433 individuals. Out of the 27 sites, 6 never allowed the observation of Bombina variegata. Among the 21 sites occupied by the toads, 3 did not allow the observation of breeding indices. Thanks to the analyses of the environmental data, we found that the presence of Bombina variegata is especially influenced by water availability. We also showed that the toads preferentially choose ponds filled between 50% and 75% of water, probably in the aim of balancing the risks due to predators that may feed on larvae and eggs, and the risk of desiccation. Our results indicate that adults Bombina variegata are less tolerant to the presence of Marsh frogs (Pelophylax ridibundus) than Italian crested newt (Triturus carnifex), and that there is no clear effect of the vegetation on the toads. The eggs and tadpoles seem to be the most demanding stage, which means that adults might consider the conditions of the ponds before spawning to increase the survival probability of their larvae. We also suggest some bias of observation due to the turbidity of water and the presence of algae or other vegetation in the ponds. Since water is so important for toads, we considered the impact of the hydroperiod on the movement and breeding of Bombina variegata. We classified the ponds into two categories: predictable ponds (buckets) and unpredictable ponds (semi-natural and natural ponds). It appeared that the detection of toads and breeding indices is higher in buckets. In both categories, the toads stay for one season without breeding, which is consistent with the idea that the animals inspect the conditions of the ponds before starting to breed. Moreover, the toads are more likely to stop breeding in and leave unpredictable ponds. Finally, the probability that an unoccupied pond welcomes breeding is higher in predictable ponds, as well as the probability that an occupied pond without breeding welcomes breeding the following year. We also investigated the resistance of the canton of Geneva to the toads’ movement using the ArcGIS tool Linkage Mapper. It appeared that the sectors of Jussy (East) and Versoix (North) are very isolated from all the other Swiss sites. The Western part of the canton seems better connected, but the Rhône acts as an impassable barrier. A more detailed analysis of the sector of Jussy showed that a potential corridor passes through the area in a North-South axis and especially through the site CAR. The protection of this site is important to keep the whole area connected. Finally, to assess the genetic diversity of Bombina variegata in Geneva, we collected DNA samples using the non-invasive buccal swab method. We analysed 12 microsatellite loci developed either for our target species or for its sister species Bombina bombina. It appeared that the genetic diversity is low, as it was demonstrated in other studies in Switzerland, though the expected heterozygosity is within the range of other studies in Europe. Moreover, the genetic differentiation is moderate. However, even though the values are similar to those in other studies, it is preoccupying that we have such a structure in such a small area. In fact, landscape fragmentation in Geneva is high and it could then likely lead to the isolation of populations. Using Structure and GeneLand softwares, we found that the animals of Geneva come from four original clusters, but that there is not a lot of difference in the attribution of the populations to the clusters. It means that the genetic material of the individuals in each population is not very different. The contrast between this result and the moderated differentiation previously found can be due to missing values in our dataset that reduced the power of the analyses, but can also have a biological explanation. Indeed, amphibians have a generation length long enough to potentially prevent the impact of landscape fragmentation to be noticed on the short term. To place all these considerations in a conservation framework, we can suggest four important guidelines to insure the protection and survival of Bombina variegata in Geneva. First, water is important for this species, so we need to protect and restore humid habitats, especially the ones that includes many temporary ponds. We need to pay particular attention to the key-sites, meaning the sites that are still presenting connections with surrounding areas where the toads are present. Then, we need further field work to detect breeding grounds that were missed and whose absence may have caused the underestimation of reproduction rate. Further prospections on French grounds could allow us to better understand the potential of dispersion around sites that are located on the border. Moreover, we need to improve the ability of dispersal within and between sites. For this, more ponds must be dug to restore or create connections between colonised areas. Amphibian passageways may also be a good way to prevent the barrier effect of important roads. Finally, the degree of genetic differentiation must be regularly monitored to notice any important increase

    Why do results conflict regarding the prognostic value of the methylation status in colon cancers? the role of the preservation method

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    <p>Abstract</p> <p>Background</p> <p>In colorectal carcinoma, extensive gene promoter hypermethylation is called the CpG island methylator phenotype (CIMP). Explaining why studies on CIMP and survival yield conflicting results is essential. Most experiments to measure DNA methylation rely on the sodium bisulfite conversion of unmethylated cytosines into uracils. No study has evaluated the performance of bisulfite conversion and methylation levels from matched cryo-preserved and Formalin-Fixed Paraffin Embedded (FFPE) samples using pyrosequencing.</p> <p>Methods</p> <p>Couples of matched cryo-preserved and FFPE samples from 40 colon adenocarcinomas were analyzed. Rates of bisulfite conversion and levels of methylation of <it>LINE-1, MLH1 </it>and <it>MGMT </it>markers were measured.</p> <p>Results</p> <p>For the reproducibility of bisulfite conversion, the mean of bisulfite-to-bisulfite standard deviation (SD) was 1.3%. The mean of run-to-run SD of PCR/pyrosequencing was 0.9%. Of the 40 DNA couples, only 67.5%, 55.0%, and 57.5% of FFPE DNA were interpretable for <it>LINE-1, MLH1</it>, and <it>MGMT </it>markers, respectively, after the first analysis. On frozen samples the proportion of well converted samples was 95.0%, 97.4% and 87.2% respectively. For DNA showing a total bisulfite conversion, 8 couples (27.6%) for <it>LINE-1</it>, 4 couples (15.4%) for <it>MLH1 </it>and 8 couples (25.8%) for <it>MGMT </it>displayed significant differences in methylation levels.</p> <p>Conclusions</p> <p>Frozen samples gave reproducible results for bisulfite conversion and reliable methylation levels. FFPE samples gave unsatisfactory and non reproducible bisulfite conversions leading to random results for methylation levels. The use of FFPE collections to assess DNA methylation by bisulfite methods must not be recommended. This can partly explain the conflicting results on the prognosis of CIMP colon cancers.</p

    Endangered species Conservation in peri-urban habitats. Study of Yellow-bellied Toads Populations (Bombina variegata) in Geneva (Switzerland) - Ethological, Ecological and Genetic Approaches

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    Our planet is strongly suffering from human activities and their consequences. Obviously, the animals and plants have to cope with the variable environmental conditions that result from these anthropic activities. The aquatic species are even more vulnerable as, often, their habitats is affected by climate. As global warming causes the temperature to rise, the increase of evaporation and consequent dryness of ponds can highly affect the survival and fitness of their inhabitants. The amphibians are the mostly threatened vertebrate group, and the Yellow-bellied toad (Bombina variegata) is one of the most endangered amphibian species in Switzerland. In an effort to improve the knowledge on Bombina variegata in Geneva to develop more efficient and robust conservation measures, we monitored 27 sites (21 Genevan and 6 French) during 1 to 5 years using capture-recapture method. In these sites, we monitored 2713 ponds of three different categories: artificial ponds (n=1302), semi-natural ponds (n=1147) and natural ponds (n=264). The first category concerns plastic buckets that were installed in the field. The second category concerns artificial ponds that were dug in the field and made waterproof thanks to clay, or other ancient man-made ponds. The last category concerns natural depressions that were mapped in each site. The sites were monitored at least once a month during the activity period of the toads, for at least one year, but the prospections were much more regular in some sites (TEP: up to 21 sessions during a year, 5 years of monitoring). This census allowed the global observation (sum of capture events) of 2655 toads from 2012 to 2016 in the whole Geneva area. These represent 1587 adults (975 males, 612 females), 737 subadults (444 males, 293 females) and 331 juveniles (52 males, 70 females and 209 not sexed). Among these observations, we were able to recognize 1107 different individuals thanks to the colouration of their belly. We were also able to count 4770 tadpoles and 7819 eggs. The global sex-ratio on the whole study area is 53:47. The observed population size per site range from 2 to 433 individuals. Out of the 27 sites, 6 never allowed the observation of Bombina variegata. Among the 21 sites occupied by the toads, 3 did not allow the observation of breeding indices. Thanks to the analyses of the environmental data, we found that the presence of Bombina variegata is especially influenced by water availability. We also showed that the toads preferentially choose ponds filled between 50% and 75% of water, probably in the aim of balancing the risks due to predators that may feed on larvae and eggs, and the risk of desiccation. Our results indicate that adults Bombina variegata are less tolerant to the presence of Marsh frogs (Pelophylax ridibundus) than Italian crested newt (Triturus carnifex), and that there is no clear effect of the vegetation on the toads. The eggs and tadpoles seem to be the most demanding stage, which means that adults might consider the conditions of the ponds before spawning to increase the survival probability of their larvae. We also suggest some bias of observation due to the turbidity of water and the presence of algae or other vegetation in the ponds. Since water is so important for toads, we considered the impact of the hydroperiod on the movement and breeding of Bombina variegata. We classified the ponds into two categories: predictable ponds (buckets) and unpredictable ponds (semi-natural and natural ponds). It appeared that the detection of toads and breeding indices is higher in buckets. In both categories, the toads stay for one season without breeding, which is consistent with the idea that the animals inspect the conditions of the ponds before starting to breed. Moreover, the toads are more likely to stop breeding in and leave unpredictable ponds. Finally, the probability that an unoccupied pond welcomes breeding is higher in predictable ponds, as well as the probability that an occupied pond without breeding welcomes breeding the following year. We also investigated the resistance of the canton of Geneva to the toads’ movement using the ArcGIS tool Linkage Mapper. It appeared that the sectors of Jussy (East) and Versoix (North) are very isolated from all the other Swiss sites. The Western part of the canton seems better connected, but the Rhône acts as an impassable barrier. A more detailed analysis of the sector of Jussy showed that a potential corridor passes through the area in a North-South axis and especially through the site CAR. The protection of this site is important to keep the whole area connected. Finally, to assess the genetic diversity of Bombina variegata in Geneva, we collected DNA samples using the non-invasive buccal swab method. We analysed 12 microsatellite loci developed either for our target species or for its sister species Bombina bombina. It appeared that the genetic diversity is low, as it was demonstrated in other studies in Switzerland, though the expected heterozygosity is within the range of other studies in Europe. Moreover, the genetic differentiation is moderate. However, even though the values are similar to those in other studies, it is preoccupying that we have such a structure in such a small area. In fact, landscape fragmentation in Geneva is high and it could then likely lead to the isolation of populations. Using Structure and GeneLand softwares, we found that the animals of Geneva come from four original clusters, but that there is not a lot of difference in the attribution of the populations to the clusters. It means that the genetic material of the individuals in each population is not very different. The contrast between this result and the moderated differentiation previously found can be due to missing values in our dataset that reduced the power of the analyses, but can also have a biological explanation. Indeed, amphibians have a generation length long enough to potentially prevent the impact of landscape fragmentation to be noticed on the short term. To place all these considerations in a conservation framework, we can suggest four important guidelines to insure the protection and survival of Bombina variegata in Geneva. First, water is important for this species, so we need to protect and restore humid habitats, especially the ones that includes many temporary ponds. We need to pay particular attention to the key-sites, meaning the sites that are still presenting connections with surrounding areas where the toads are present. Then, we need further field work to detect breeding grounds that were missed and whose absence may have caused the underestimation of reproduction rate. Further prospections on French grounds could allow us to better understand the potential of dispersion around sites that are located on the border. Moreover, we need to improve the ability of dispersal within and between sites. For this, more ponds must be dug to restore or create connections between colonised areas. Amphibian passageways may also be a good way to prevent the barrier effect of important roads. Finally, the degree of genetic differentiation must be regularly monitored to notice any important increase.Il nostro pianeta soffre enormemente delle attività antropiche e delle loro conseguenze e, chiaramente, gli animali devono confrontarsi con le condizioni ambientali variabili che ne conseguono. Le specie acquatiche sono particolarmente vulnerabili in quanto, spesso, il loro habitat è fortemente influenzato dal clima del pianeta. Dato che il riscaldamento climatico implica un innalzamento delle temperature, la maggior evaporazione ed il conseguente aumento del prosciugamento di stagni e specchi d’acqua può influenzare in maniera grave la sopravvivenza e il successo riproduttivo delle specie presenti in questi ambienti. Tra i vertebrati, gli anfibi sono i più minacciati, e tra gli anfibi più minacciati in Svizzera vi è il rospo ululone dal ventre giallo (Bombina variegata). Per meglio conoscere Bombina variegata a Ginevra e ottenere informazioni utili ai fini conservazionistici, la specie è stata studiata, mediante un approccio di cattura-ricattura, in 27 siti (21 ginevrini e 5 francesi). In questi siti abbiamo controllato 2713 tra stagni e pozze d’acqua, suddivisi in tre diverse categorie: artificiali (n = 1302), semi-naturali (n = 1147) e naturali (n = 264). La prima categoria è rappresentata da secchi di plastica appositamente sistemati sul terreno. La seconda categoria si riferisce a siti d’acqua artificiali, scavati nel terreno e impermeabilizzati con argilla durante questo studio, oppure ad altri punti costruiti dall’uomo e già presenti in loco. L’ultima categoria è rappresentata da depressioni naturali che sono state cartografate in ognuno dei siti. I siti sono stati ispezionati almeno una volta al mese durante il periodo di attività dei rospi, per almeno un anno, ma in certi siti le prospezioni sono state più regolari e prolungate (TEP: fino a 21 sessioni in un anno e per 5 anni). Questo censimento ha permesso l’osservazione globale (somma degli episodi di cattura) di 2655 rospi dal 2012 al 2016 su tutto il bacino ginevrino. Si tratta di 1587 adulti (975 maschi, 612 femmine), 737 sub-adulti (444 maschi, 293 femmine) e 331 giovanili (52 maschi, 70 femmine e 209 con sesso no determinato). Complessivamente, grazie alla colorazione del ventre, è stato possibile riconoscere 1107 diversi individui tra le 2655 osservazioni. Sono stati inoltre osservati 4770 girini e 7819 uova. Il rapporto tra i sessi, calcolato complessivamente per tutta la zona studiata, è di 53:47. Le popolazioni osservati variano di numero da 2 a 433 individui per sito. Sui 27 siti studiati, 6 non hanno permesso di osservare Bombina variegata. La riproduzione non è stata osservata in 3 dei 21 siti in cui sono stati trovati rospi. Grazie all’analisi dei dati ambientali è stato possibile rilevare come la presenza di Bombina variegata sia influenzata soprattutto dalla disponibilità di acqua. E’ stato anche dimostrato che i rospi preferiscono stagni e pozze d’acqua con un riempimento d’acqua che va dal 50% al 75%, probabilmente allo scopo di controbilanciare i rischi legati ai predatori che possono nutrirsi di larve e di uova e il rischio di prosciugamento. I risultati ottenuti indicano che gli adulti di Bombina variegata tollerano meno la presenza di rane verdi maggiori (Pelophylax ridibundus) che quella di tritoni crestati italiani (Triturus carnifex), e che non c’è un effetto marcato della vegetazione sull’abbondanza di rospi. Uova e girini sono le classi di età più esigenti, il che implica che la scelta da parte degli adulti, prima di deporre le uova, di un punto d'acqua con condizioni adeguate, è fondamentale per aumentare la probabilità di sopravvivenza delle uova stesse. Lo studio effettuato ha inoltre fornito alcune indicazioni sul fatto che alcuni fattori, come la torbidità dell’acqua e la presenza di alghe o di altra vegetazione nei punti d’acqua, potrebbero avere influito sulle osservazioni. Data l’importanza dell’acqua per i rospi, abbiamo preso in considerazione l’impatto dell’idro-periodo sul movimento e sulla riproduzione di Bombina variegata. I punti d’acqua sono stati classificati in due categorie: punti d’acqua prevedibili (vasche) o imprevedibili (aree semi-naturali e naturali). È chiaro che il reperimento di rospi e gli indici di riproduzione sono più elevati nelle vasche. In entrambe le categorie i rospi rimangono per una stagione senza riprodursi, il che è consistente con il concetto che gli animali valutano le condizioni dei punti d’acqua prima di cominciare a riprodursi. Per di più, i rospi possono interrompere la riproduzione e abbandonare i punti d’acqua imprevedibili. Finalmente, la probabilità che un punto d’acqua libero diventi un sito di riproduzione è più alta nelle aree prevedibili, come pure la probabilità che un punto d’acqua occupato ma senza riproduzione diventi sito di riproduzione l’anno successivo. Utilizzando l’ArcGIS Linkage Mapper abbiamo pure studiato la resistenza del cantone di Ginevra verso il movimento dei rospi. Si è evidenziato che i settori di Jussy (Est) e di Versoix (Nord) sono molto isolati rispetto agli altri siti svizzeri. La parte Ovest del cantone sembra meglio collegata, ma il Rodano svolge un ruolo di barriera invalicabile. Un’analisi più dettagliata del settore di Jussy ha dimostrato che un corridoio potenziale passa attraverso la zona in un asse Nord-Sud e soprattutto attraverso il sito CAR. La protezione di questo sito è importante per far sì che la zona intera resti collegata. Infine, per studiare la diversità genetica di Bombina variegata a Ginevra abbiamo raccolto campioni di DNA col metodo non invasivo dello striscio buccale. Abbiamo analizzato 12 microsatelliti sviluppati sia per la nostra specie in studio sia per la sua specie sorella, Bombina bombina (ululone dal ventre rosso). Si è evidenziato che la diversità genetica è bassa, come dimostrato in altri studi in Svizzera, nonostante che l’eterozigosi attesa rimanga nell’ambito degli altri studi europei. Inoltre la differenziazione genetica è modesta. Ciò nonostante, è preoccupante che vi sia una tale struttura in una zona così ristretta. Ciò suggerisce che la frammentazione del territorio di Ginevra sia alta e suscettibile di causare l’isolamento delle popolazioni di rospi. Attraverso il programma Structure e GenLand abbiamo trovato che gli animali di Ginevra discendono da quattro gruppi d’origine, ma che non esiste una grande differenza nell’attribuire le popolazioni ai raggruppamenti. Ciò vuol dire che il materiale genetico degli individui in ogni popolazione non è molto differente. Il contrasto tra questo risultato e la differenziazione moderata trovata in precedenza può essere dovuto a dei valori mancanti nella nostra serie di dati che riducono la potenza dell’analisi, ma può avere ugualmente una spiegazione biologica. In effetti gli anfibi hanno tempi di generazione abbastanza lunghi perché l’impatto della frammentazione del paesaggio sia evidente in tempi brevi. Per porre tutte queste considerazioni nel quadro della conservazione delle specie, possiamo suggerire quattro importanti linee di condotta per assicurare la protezione e la sopravvivenza di Bombina variegata a Ginevra. In primo luogo, per questa specie l’acqua è importante, per cui dobbiamo proteggere e ripristinare le zone umide, in particolare quelle che includono punti d’acqua temporanei. Dobbiamo prestare un’attenzione particolare ai siti-chiave, cioè ai siti che presentano ancora collegamenti con le zone circostanti dove sono presenti i rospi. Poi, abbiamo bisogno di un lavoro supplementare sul terreno per individuare siti di riproduzione che non sono stati rilevati portando a una sottostima del tasso di riproduzione. Ulteriori prospezioni nelle zone francesi possono permetterci di comprendere meglio il potenziale di dispersione intorno ai siti localizzati sulla frontiera. Dobbiamo inoltre migliorare la capacità di dispersione all’interno e tra i siti. A questo fine punti d’acqua supplementari devono essere creati per ripristinare le connessioni tra le zone colonizzate. Degli ecodotti per batraci possono anche essere un buon metodo per prevenire l’effetto-barriera rappresentato da strade importanti. Infine, stime del grado di differenziazione genetica devono essere effettuate regolarmente per evidenziare un aumento importante

    Interview sur les femmes immigrées

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    info:eu-repo/semantics/publishe

    Manipulating waterbody hydroperiod affects movement behaviour and occupancy dynamics in an amphibian

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    Species that occur in ephemeral habitats such as temporary waterbodies have evolved specific strategies that allow them to respond to spatial and temporal variations in water availability and quality. Their life-history strategies, involving complex life cycles, have evolved to allow individuals to escape deteriorating environmental conditions when a waterbody dries up. These adaptations have led to the emergence of complex movement behaviour, which might then be expected to affect the spatiotemporal dynamics of reproduction. To date, few empirical studies have investigated how the risks of waterbody drying out affects movement behaviour at the individual level and how movement decisions then shape waterbody occupancy dynamics. In this study, we examined this issue in an endangered amphibian, the yellow-bellied toad (Bombina variegata). For this purpose, we experimentally manipulated waterbody hydroperiod and collected capture-recapture and presence-absence data in 334 waterbodies located in 15 B.variegata populations in the region of Geneva (Switzerland) during a 5-year period (2012-2016). The results of our analyses reveal that the waterbody hydroperiod affects this species' movement behaviour. Adults were less likely to leave waterbodies with a long hydroperiod both intra- and inter-annually. In addition, breeding occupancy strongly depended on a waterbody's hydroperiod. In particular, interannual changes in breeding occurrence were less frequent in waterbodies with a long hydroperiod. Our findings show that the hydroperiod strongly affects ecological processes at different levels, from individuals' movement decisions to waterbody occupancy dynamics. The results demonstrate that adults adjust their movement decisions according to the risk of breeding failure driven by the hydroperiod, which then affects the waterbody occupancy dynamics

    Effects of apple form on energy intake during a mid-afternoon snack: A preload paradigm study in school-aged children

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    International audienceConsuming foods with a form or a texture that requires longer oral processing is a way to decrease food intake. Although this approach is promising for leveraging healthier eating patterns in adults, it has never been explored in children. This study evaluated whether starting a mid-afternoon snack by eating either apple segments or applesauce would modify hunger and subsequent food intake during this meal. Forty-four children (8–10 years old) participated in two videotaped mid-afternoon snacks, during which they received one of the two forms of apple as a food preload followed 10 min later by ad libitum consumption of sweetened cottage cheese. They self-reported their level of hunger throughout consumption, and the weight of cottage cheese consumed was determined at the end of the snack. Children's chewing capabilities and eating traits were parent-reported. Eating a raw apple increased oral exposure time and decreased bite size compared to eating applesauce. However, neither the reported hunger nor consecutive food intake were modified. Regardless of the meal, children eating fast had a higher ad libitum energy intake. The individual eating rate for the cottage cheese was correlated with the eating rate observed for applesauce but not for apple segments, the latter being associated with children's chewing difficulties. This study suggests that the form of a fruit offered at the start of a mid-afternoon snack does not impact food intake; the findings clearly call for more exploration of satiation mechanisms related to food texture properties among children and indicate the need to consider children's oral processing skills
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