127 research outputs found

    Analyse UBM du site de filtration aprÚs sclérectomie profonde postérieure modifiée utillisant un tube Ex-PRESS? X-50

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    Purpose: To study the filtering site using ultrasound biomicroscopy. (UBM) after posterior deep sclerectomy with Ex-PRESS? X-50 implant in patients undergoing filtering surgery.ŠMethods: Twenty-six patients that participated in this prospective, non comparative study underwent a posterior deep sclerectomy and an Ex- PRESS? X-50 tube implantation. Clinical outcome factors recorded include: intraocular pressure, number of antiglaucoma medications, best corrected visual acuity (BCVA), frequency and types of complications. Six months postoperatively, an ultrasound biomicroscopy examination was performed.ŠResults: Mean follow up was 12.0±3.4 months. Mean IOP decreased from 21 ±5.7 mmHg to 12.4±3 mmHg. At last follow-up examination, 65% of eyes had a complete success and 30% a qualified success. The mean number of antiglaucoma medications decreased from 2.5±1.2 preoperatively to 0.7±1 at the last follow-up postoperatively. BCVA was not changed. 27 complications were observed. On the UBM images, the mean intrascleral space volume was 0.25±0.27 mm3 and no relationship was found between volume and intraocular pressure reduction. We noted in 5/26 (19%) eyes a suprachoroĂŻdal hypoechoic. Low-reflective blebs (L-type) were the most common: 15/26 (58%). No correlation between UBM findings and surgical success was evident.ŠConclusions: Deep sclerectomy with Ex-PRESS? X-50 tube implantation seems an efficient glaucoma surgery. It allows satisfactory IOP reduction with a low number of post operative complications. The advantages of deep sclerectomy with collagen implant are maintained with this modified technique. In both, the same reflective types of filtering blebs are present (high, low, encapsulated and flat). The UBM underlines the three mechanisms of aqueous humor resorption previously identified but no correlation with surgical success can be proved.Š-ŠCe travail de thĂšse est une analyse par ultrasonographic biomicroscopique (UBM) du site de filtration aprĂšs sclĂ©rectomie profonde postĂ©rieure modifiĂ©e avec implantation d'un tube Ex- PRESS? X-50.ŠVingt six patients atteints d'un glaucome Ă  angle ouvert, ont participĂ© Ă  cette Ă©tude prospective et non-comparative. Le critĂšre d'inclusion est un glaucome Ă  angle ouvert non contrĂŽlĂ© malgrĂ© un traitement topique maximal.ŠDiffĂ©rents types de chirurgie filtrante sont effectuĂ©s dans la chirurgie du glaucome dont la trabĂ©culectomie et la sclĂ©rectomie profonde.ŠL'intervention chirurgicale pratiquĂ©e dans cette Ă©tude consiste en l'implantation d'un tube Ex-PRESS? X-50 de format dĂ©fini (3 mm de longueur et 50 ΌπÎč de diamĂštre interne) dans la chambre antĂ©rieure,au niveau du trabeculum, sous un volet sclĂ©ral, ce qui permet le drainage de l'humeur aqueuse vers les espaces sous-conjonctivaux, avec diminution de la pression intraoculaire.ŠCette technique implique uniquement une dissection d'un volet sclĂ©ral superficiel , sans volet sclĂ©ral profond comme d'une sclĂ©rectomie profonde classique.ŠLes modes de fonctionnement de cette sclĂ©rectomie profonde modifiĂ©e sont explorĂ©s par UBM, qui donne des images Ă  haute rĂ©solution, semblables Ă  des coupes anatomiques. Le volume de l'espace intrasclĂ©ral crĂ©Ă© artificiellement peut en effet ĂȘtre mesurĂ© et mis en corrĂ©lation avec la pression intraoculaire et donc avec le taux de succĂšs. Les diffĂ©rents types d'Ă©chogĂ©nĂ©citĂ© de la bulle de filtration sous-conjonctivale provoquĂ©e par la dĂ©rivation de l'humeur aqueuse sont Ă©galement observĂ©s. La prĂ©sence Ă©ventuelle d'une filtration supplĂ©mentaire au niveau choroĂŻdien est aussi dĂ©tectĂ©e.ŠDe fĂ©vrier 2007 Ă  juin 2008, nous avons suivi chez les vingt six yeux des vingt six patients le volume intrasclĂ©ral, la filtration sous-conjonctivale et la filtration choroĂŻdienne le cas Ă©chĂ©ant, de mĂȘme que l'acuitĂ© visuelle, la pression intraoculaire, le nombre de traitement antihypertenseur topique et les complications.ŠLes rĂ©sultats dĂ©montrent une rĂ©duction de 41 % par rapport Ă  la pression intraoculaire prĂ©opĂ©ratoire, ce qui est statistiquement significatif (p<0.0005). En ce qui concerne l'acuitĂ© visuelle, les valeurs demeurent stables. Par ailleurs, le nombre de mĂ©dicaments antiglaucomateux diminue de façon significative de 2.5 ± 1.2 en prĂ©opĂ©ratoire Ă  0.7 ± 1.0 au dernier examen (p<0.0005). Le volume de l'espace intrasclĂ©ral, apparaissant toujours en Ă©chographie d'aspect fusiforme, n'est pas corrĂ©lĂ© de façon significative avec un meilleur succĂšs chirurgical bien que l'on aperçoive une tendance Ă  une corrĂ©lation entre un plus grand volume et une pression intraoculaire plus basse.ŠLa classification la bulle de filtration se fait selon les 4 catĂ©gories de bulle de filtration dĂ©crites dans la littĂ©rature. La rĂ©partition rĂ©vĂšle une majoritĂ© de type L soit hypoĂ©chogĂšne: 15/26 (58%) et une proportion identique, soit, 4/26 (16%), de bulles hyperĂ©chogĂšnes (type H) et encapsulĂ©es (type E); les bulles de filtration plates et hyperĂ©chogĂšnes (type F) sont les moins nombreuses 3/26 (11 %).ŠLa ligne hyporĂ©flective visible dans 19 % des cas entre la sclĂšre et la choroĂŻde reprĂ©sentant potentiellement un drainage suprachoroĂŻdien, n'est pas associĂ©e statistiquement Ă  une meilleure filtration et une pression intraoculaire plus basse mais demeure une troisiĂšme voie de filtration, en plus de la filtration sous-conjonctivale et intrasclĂ©rale.ŠEn conclusion, cette technique diffĂ©rente, offrant une plus grande sĂ©curitĂ© et des rĂ©sultats satisfaisants sur l'abaissement de la pression intraoculaire, peut ĂȘtre, dans certains cas, une alternative Ă  la sclĂ©rectomie profonde classique ,dont elle partage les mĂ©canismes de filtration objectivĂ©s par ultrasonographic biomicrioscopique

    Iron limitation in the Western Interior Seaway during the Late Cretaceous OAE 3 and its role in phosphorus recycling and enhanced organic matter preservation

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    The sedimentary record of the Coniacian–Santonian Oceanic Anoxic Event 3 (OAE 3) in the North American Western Interior Seaway is characterized by a prolonged period of enhanced organic carbon (OC) burial. This study investigates the role of Fe in enhancing organic matter preservation and maintaining elevated primary productivity to sustain black shale deposition within the Coniacian–Santonian-aged Niobrara Formation in the USGS #1 Portland core. Iron speciation results indicate the development of a reactive Fe limitation coeval with reduced bioturbation and increased organic matter preservation, suggesting that decreased sulfide buffering by reactive Fe may have promoted enhanced organic matter preservation at the onset of OAE 3. An Fe limitation would also provide a feedback mechanism to sustain elevated primary productivity through enhanced phosphorus recycling. Additionally our results demonstrate inconsistencies between Fe-based and trace metal redox reconstructions. Iron indices from the Portland core indicate a single stepwise change, whereas the trace metal redox proxies indicate fluctuating redox conditions during and after OAE 3. Using Fe speciation to reconstruct past redox conditions may be complicated by a number of factors, including Fe sequestration in diagenetic carbonate phases and efficient sedimentary pyrite formation in a system with limited Fe supply and high levels of export production

    Assessing oxygen depletion in the Northeastern Pacific Ocean during the last deglaciation using I/Ca ratios from multiple benthic foraminiferal species

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    Paleo‐redox proxies are crucial for reconstructing past bottom water oxygen concentration changes brought about by ocean circulation and marine productivity shifts in response to climate forcing. Carbonate I/Ca ratios of multiple benthic foraminifera species from Ocean Drilling Program Hole 1017E—a core drilled within the Californian oxygen minimum zone (OMZ), on the continental slope—are employed to reexamine the transition from the well‐oxygenated last glacial into poorly oxygenated modern conditions. The redox and export productivity history of this site is constrained by numerous proxies used to assess sensitivity of I/Ca ratios of benthic foraminifera to changes in bottom and pore water O2 concentrations. Reconstructed iodate (IO3−) availability is from the I/Ca ratio of epifaunal (Cibicidoides sp.), shallow infaunal (Uvigerina peregrina), and deep infaunal (Bolivina spissa) foraminifera. The reconstructed IO3− availability profile is used to determine the contribution of bottom water O2 relative to oxidant demand on pore water O2 concentrations. These results suggest that high export productivity on the California Margin drove low pore water O2 concentrations during the Bþlling. In contrast, low bottom water O2 concentrations at 950 m water depth only contributed to reduced sediments during the Allerþd. Increased contribution of modified North Pacific Intermediate Water to the California Current System ventilated the California OMZ during the late glacial and the Younger Dryas such that water overlying the site was oxygenated. These results highlight the promising potential of this new proxy for understanding the relative influence of bottom water O2 concentration and pore water oxidant demand on OMZs.Plain Language SummaryIodine is a highly redox‐sensitive element, is well mixed in the ocean, and is one of the first elements to respond to changes in ocean redox. In an oxic water column it is found as IO3−, and with decreasing dissolved O2 concentration it is reduced to I−. In foraminiferal calcite, iodate is thought to substitute for carbonate ions proportionate to the IO3− concentration of the water column, with the potential to be a quantitative proxy for detecting changes in oxygenation of bottom waters. However, core top studies indicate significant interspecies variability of I/Ca in response to O2. Here we measured the I/Ca ratios of multiple benthic foraminiferal species from Ocean Drilling Program‐1017E, a high‐resolution core on the California margin of the Northeast Pacific Ocean, to reconstruct bottom and pore water iodate availability to reexamine the oxygenation history of the California oxygen minimum zone to investigate the potential of this proxy for reconstructing the relative influence of bottom and pore water oxidant demand in response to millennial‐scale climate changes compared with previously published trace metal redox proxies.Key PointsThree benthic foraminifera species show expected I/Ca ratios in Northeast Pacific core record relative to their depth habitatForaminiferal I/Ca‐based O2 reconstructions are supported by multiple proxies in the same sediment samplesOxidant demand was greatest during the Bþlling; pore and bottom waters were most oxygenated during the Younger Dryas and last glacialPeer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/138363/1/palo20430_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/138363/2/palo20430.pd

    Interactions zooplancton-poissons dans une retenue oligotrophe de mise en eau récente (Ste-Croix, Provence, France)

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    Les peuplements zooplanctoniques et piscicoles de la retenue de Sainte-Croix (lac oligotrophe profond) ont été suivis de la mise en eau (1974) à 1986.La phase initiale de colonisation (1974-1975), caractérisée par le calanide Acanthodiaptomus denticornis et la dominance des espÚces piscicoles peuplant antérieurement le Verdon lotique (Barbus fluvatilis, Leuciscus cephalus) a été de courte durée. Par la suite, les cladocÚres sont restés dominants avec cependant de profondes modifications dans la structure du peuplement. En 1977-78, Daphnia longispina était dominante tout au long de l'année (76 %). Plus récemment, cette espÚce ne représentait plus que 34 %. des effectifs (1983-84), puis 24 % (1985-1986). La situation actuelle est caractérisée par la présence de Diaphanosoma brachyurum en été et l'abondance des petites formes (bosmines).L'ichtyofaune s'est elle aussi modifiée avec, notamment, une importante population d'ablette (Alburnus cluburnus), exploitant la zone pélagique. Son régime alimentaire est largement zooplanctonophage mais inclut mollusques et insectes lorsqu'elle est capturée en zone littorale.Cette augmentation de la pression de prédation a entraßné un net déplacement du spectre des tailles du zooplancton vers tes classes inférieures à 0,8 mm en 1986 (82 %) alors que les grandes formes ( > à 1 mm) représentaient 60 % des effectifs en 1977-78. Les densités de D. longispina et D. brachyurum décroissent rapidement entre 1983 et 1986.Les conséquences de cette prédation sélective sont discutées (évolution prévisible du systÚme) ainsi que les causes pouvant expliquer l'absence de régulation efficace (densité-dépendance) dans un tel systÚme prédateur-proie.The aim of this study was to identify relationships between changes that occurred, from 1974 to 1986, both in the limnetic zooplankton and the fish communities of the large reservoir of Sainte-Croix (Southern France).This reservoir (figure 1) is characterized by a capacity of 767 hm3 and a long average renewal period (280 days). It was filled up in 1974. Changes in levels can attain 16 m, especially in winter. During summer, the lake is clearly stratified : surface mater temperatures are about 22-250°C whereas waters below the thermocline are cooler ( < 10° C) but well oxygenated (more than 50 % saturation). According to the mean annual total phosphorus (19 mg/m3) and chlorophyll a (ranging from 0.5 to 2 mg/m3), the lake is oligotrophic.The zooplankton was collected with a Clarke-Bumpus devise sampler (125 ”m mesh-size) during both the 1974-1978 and the 1983-1984 periods. More recently (1985-1986), vertical hauls of zooplankton were made with a 50 ”m mesh-size aperture net. Only relative abundance of large species (excluding small rotifers) have been taken into account for comparisons between different periods (figure 2). For the last four years (1983-1986), a set of data on filtration efficiency and comparison between sampling methods provides information concerning the evolution of annual mean densities of zooplankton species (figure 3).Successive inventories of the fish species were made in 1976, 1977, 1984 and 1987 at the same location with 15 mm, 27 mm and 50 mm mesh-size nets respectively. Figure 1 shows that abundant autochtonous species (Chondrostoma chondrostoma, Barbus fluviatilis) during the first period (1976-1977) are now relatively scarce, whereas the roach (Rutilus rutilus), an introduced species, is now largely dominant. Likewise, the relative abundance of the bleak, Alburnus alburnus, also increased, especially during the last period (1984-1987). Only this last species was caught by fine mesh-size nets in the pelagic epilimnion. Adults fed mostly on zooplankton but also took more molluscs in the littoral area (stomach analysis).In 1974, one year after an overflow, the calanoid Acanthodiaptomus denticornis represented the majority of zooplankton collected but it disappeared quickly. Since 1976, cladocerans are largely dominant. General evolutive trends show a decrease in relative abundance of Daphnia longispina from 1978 to 1986 whereas Diaphanosoma brachyurum have been recorded since 1983. Quantitative data (figure 3), available for the fast 4 years (1983-1986) show that the population densities of both these two large cladoceran and cyclopoïd species (mainly Macrocyclops albius) declined radically. On the other hand, small species such as Bosmina longirostris, Bosmina coregoni and Asplancha priodonta exhibited the same population densities throughout the fast period. Comparisons of phytoplankton community structure from 1982 to 1986 do not show signicative trends. Thus, variations in resource abundance cannot explain the long-term evolution of zooplankton communities.By comparing the mean annual length frequency distributions of zooplankton in 1977-78 and 1986 (figure 4), a marked decline of large bodied forms is seen. The individuals larger than 1.0 mm represented 60 % of total organisms in 1977-73 against 14.5 % in 1986. Mean annual lenghts were 0.8 mm in 1977-78 and 0.3 mm in 1986. These results are in good agreement with BROOKS and DODSON hypothesis that planktivorous fish can have a profound effect on zooplankton community taxonomics and size structure. They show that the control of structure and abundance of zooplankton by fish predation in new man-made lakes is a reality.Most fish are general predators. As demonstrated by MURDOCH and BENCE (1987), this can explain the instability of the coupled predator-prey system in the pelagic portion of Sainte-Croix reservoir because of : i) the capacity of the bleak to use fat reserves and to change its diet when large zooplankton prey density is too low, ii) the generation time of the predator is much longer than that of planktonic preys. Thus, the classical density-dependence mechanisms do not stabilize the predator-prey system and the main planktonic prey tend to disappear (D. longispina, in our case).Nevertheless, some potentially stabilizing mechanisms could interfere in the system before the local extinction of the prey : compensatory responses by the prey and significant changes in the fish community. There is reason to consider :1) The existence of refuges in space. Vertical size distribution of D. longispina (unpublished data) show that there is a strong vertical size gradient during daylight hours. Larger-bodied reproductive forms (longer than 1 mm) are only present in the deeper layers (20-30 m) whereas, during the night all the organises migrate to the superficial layer.2) The existence of refuge in time. In the past (1976-1978), D. longispina was dominant all year around. More recently (1983-1986), population densities were high only in spring (figure 5). From April to June, bleaks tend to assemble in the littoral zone for reproduction.3) An increase in the bleak mortality rate due to a recent development of large predator populations, such as Esox esox, could permit a reduction or, at least, a stabilization of the bleak population growth rate

    Redox Chemistry and Molybdenum Burial in a Mesoproterozoic Lake

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    While marine sediments have been used to constrain a history of redox chemistry throughout the Precambrian, far fewer data have been generated from lakes. With major biological innovations thought to have occurred in Proterozoic lakes, understanding their chemistry is critical for understanding the evolution of eukaryotic life. We use sediment geochemistry to characterize the redox conditions of the Nonesuch Formation (~1.1 Ga) and a modern analogue for the Proterozoic: the Middle Island Sinkhole in Lake Huron (USA). Iron speciation, Mo contents, and Mo‐U covariation demonstrate oxic and anoxic—not euxinic—environments, with no clear indicators of enhanced biological productivity in the Nonesuch Formation. Moderate Mo enrichments observed in the Nonesuch Formation are not attributed to euxinia, but instead to an authigenic particulate shuttle. We suggest that the Fe and Mo sediment geochemistry of these lacustrine systems reflect only local water column and sediment burial conditions and not atmospheric oxygenation.Plain Language SummaryLakes are proposed to have been critical environments for the evolution of life during the Proterozoic (~2.5 to 0.5 billion years ago). However, relatively little is known about the chemistry of ancient lakes, including the availability of oxygen for biological productivity, and how local oxygen availability can be extrapolated to understand global oxygen availability. In addition, with no lakes remaining from the Proterozoic, the only way to study ancient lakes is to use the chemistry of the sediments left behind. This study uses the sediment chemistry of elements that are sensitive to oxygen to understand oxygen availability in a Proterozoic lake environment. These data were then compared to modern lake environments with known chemistry and oxygen levels in order to interpret the results better. We found that oxygen availability in the Proterozoic lake was variable, with no clear indicators of abundant biological productivity. We conclude that ancient lake sediments only constrain the chemistry of the local environment, with no major implications for global or even regional atmospheric oxygenation.Key PointsFe, Mo, and U sediment geochemistry of the Nonesuch Formation (~1.1 Ga; USA) indicate fluctuating oxic and anoxic redox chemistryMo and U covariation in the Nonesuch Formation and modern analogue sediments confirm euxinia is not necessary for moderate Mo burialComparison of Nonesuch Formation and modern analogue indicates that Proterozoic lakes are unlikely to constrain atmospheric oxygenPeer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/150528/1/grl59087_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/150528/2/grl59087.pd

    Interleukin-7 Links T Lymphocyte and Intestinal Epithelial Cell Homeostasis

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    Interleukin-7 (IL-7) is a major survival factor for mature T cells. Therefore, the degree of IL-7 availability determines the size of the peripheral T cell pool and regulates T cell homeostasis. Here we provide evidence that IL-7 also regulates the homeostasis of intestinal epithelial cells (IEC), colon function and the composition of the commensal microflora. In the colon of T cell-deficient, lymphopenic mice, IL-7-producing IEC accumulate. IEC hyperplasia can be blocked by IL-7-consuming T cells or the inactivation of the IL-7/IL-7R signaling pathway. However, the blockade of the IL-7/IL-7R signaling pathway renders T cell-deficient mice more sensitive to chemically-induced IEC damage and subsequent colitis. In summary, our data demonstrate that IL-7 promotes IEC hyperplasia under lymphopenic conditions. Under non-lymphopenic conditions, however, T cells consume IL-7 thereby limiting IEC expansion and survival. Hence, the degree of IL-7 availability regulates both, T cell and IEC homeostasis

    Homeostatic apoptosis prevents competition-induced atrophy in follicular B cells

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    While the intrinsic apoptosis pathway is thought to play a central role in shaping the B cell lineage, its precise role in mature B cell homeostasis remains elusive. Using mice in which mature B cells are unable to undergo apoptotic cell death, we show that apoptosis constrains follicular B (FoB) cell lifespan but plays no role in marginal zone B (MZB) cell homeostasis. In these mice, FoB cells accumulate abnormally. This intensifies intercellular competition for BAFF, resulting in a contraction of the MZB cell compartment, and reducing the growth, trafficking, and fitness of FoB cells. Diminished BAFF signaling dampens the non-canonical NF-ÎșB pathway, undermining FoB cell growth despite the concurrent triggering of a protective p53 response. Thus, MZB and FoB cells exhibit a differential requirement for the intrinsic apoptosis pathway. Homeostatic apoptosis constrains the size of the FoB cell compartment, thereby preventing competition-induced FoB cell atrophy.StĂ©phane Chappaz, Kate McArthur, Liam Kealy, Charity W. Law, Maximilien Tailler, Rachael M. Lane ... et al

    Non-Sexual Transmission of Trichomonas vaginalis in Adolescent Girls Attending School in Ndola, Zambia

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    OBJECTIVES: To identify risk factors for trichomoniasis among young women in Ndola, Zambia. METHOD: The study was a cross-sectional study among adolescent girls aged 13-16 years in Ndola, Zambia. Study participants were recruited from schools in selected administrative areas that represented the different socio-economic strata in town. Consenting participants were interviewed about their socio-demographic characteristics; sexual behaviour; and hygiene practices. Self-administered vaginal swabs were tested for Trichomonas vaginalis. HSV-2 antibodies were determined on serum to validate the self-reported sexual activity. RESULTS: A total of 460 girls participated in the study. The overall prevalence of trichomoniasis was 27.1%, 33.9% among girls who reported that they had ever had sex and 24.7% among virgins. In multivariate analysis the only statistically significant risk factor for trichomoniasis was inconsistent use of soap. For the virgins, none of the risk factors was significantly associated with trichomoniasis, but the association with use of soap (not always versus always) and type of toilet used (pit latrine/bush versus flush toilet) was of borderline significance. CONCLUSION: We found a high prevalence of trichomoniasis in girls in Ndola who reported that they had never had sex. We postulate that the high prevalence of trichomoniasis in virgins in Ndola is due to non-sexual transmission of trichomoniasis via shared bathing water and inconsistent use of soap

    Molybdenum Geochemistry in Salt Marsh Pond Sediments

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    The concentration and isotopic composition of sedimentary molybdenum (Mo) has been used to distinguish different redox environments in modern marine settings and in the geological record. We report Mo concentrations and ή98Mo from porewaters and sediments in three anoxic East Anglian salt marsh pond environments: (1) ‘iron-rich’ sediments containing high concentrations of dissolved ferrous iron (up to 2 mM), (2) ‘sulfide-rich’ sediments containing very high concentrations of aqueous sulfide (up to 10 mM) and, (3) sediments that we consider to be intermediate between ‘iron-rich’ and ‘sulfide-rich’ conditions. In iron-rich sediments, we suggest that iron speciation and mineralogy controls the concentration and isotopic composition of Mo. Despite similar aqueous sulfide profiles, the intermediate and sulfide-rich pond sediment have different porewater Mo concentrations and ή98Mo. In the sulfide-rich pond sediment, we suggest that the concentration and isotopic composition of Mo is controlled by solubility equilibrium with an Fe-Mo-S mineral species (e.g. FeMoS4) due to similarities in sediment and porewater ή98Mo throughout the sediment column. In the intermediate pond sediment, we conclude that active breakdown of iron oxides redistributes porewater Mo, observable as a peak of dissolved Mo (>100ppb), which diffuses within the sedimentary porewaters. The sedimentary ή98Mo is higher in sulfide-rich and intermediate pond sediment (mean = 1.66‰, range = 0.98–1.92‰) than in iron-rich pond sediment (mean = 1.10‰, range = 0.28–1.65‰) with all ponds having sedimentary ή98Mo that is lower than seawater. The maximum sedimentary ή98Mo observed in these anoxic sediments, which is 0.5-0.7‰ lower than seawater, appears to be set by Fe-Mo-S equilibration with ambient thiomolybdate species. We suggest diagenetic overprinting can cause more efficient capture of pond water Mo and causes sediment ή98Mo of originally iron-rich pond sediment to evolve to higher values at progressively higher aqueous sulfide concentrations

    Cross-species amplification of 41 microsatellites in European cyprinids: A tool for evolutionary, population genetics and hybridization studies

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    <p>Abstract</p> <p>Background</p> <p>Cyprinids display the most abundant and widespread species among the European freshwater Teleostei and are known to hybridize quite commonly. Nevertheless, a limited number of markers for conducting comparative differentiation, evolutionary and hybridization dynamics studies are available to date.</p> <p>Findings</p> <p>Five multiplex PCR sets were optimized in order to assay 41 cyprinid-specific polymorphic microsatellite loci (including 10 novel loci isolated from <it>Chondrostoma nasus nasus, Chondrostoma toxostoma toxostoma </it>and <it>Leuciscus leuciscus</it>) for 503 individuals (440 purebred specimens and 63 hybrids) from 15 European cyprinid species. The level of genetic diversity was assessed in <it>Alburnus alburnus, Alburnoides bipunctatus, C. genei, C. n. nasus, C. soetta, C. t. toxostoma, L. idus, L. leuciscus, Pachychilon pictum, Rutilus rutilus, Squalius cephalus </it>and <it>Telestes souffia</it>. The applicability of the markers was also tested on <it>Abramis brama, Blicca bjoerkna </it>and <it>Scardinius erythrophtalmus </it>specimens. Overall, between 24 and 37 of these markers revealed polymorphic for the investigated species and 23 markers amplified for all the 15 European cyprinid species.</p> <p>Conclusions</p> <p>The developed set of markers demonstrated its performance in discriminating European cyprinid species. Furthermore, it allowed detecting and characterizing hybrid individuals. These microsatellites will therefore be useful to perform comparative evolutionary and population genetics studies dealing with European cyprinids, what is of particular interest in conservation issues and constitutes a tool of choice to conduct hybridization studies.</p
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