Ioanna Katsiadaki

Publications (70) View all

• Source

  Available from: Chauvigné François

  Article: Piscine Follicle-Stimulating Hormone Triggers Progestin Production in Gilthead Seabream Primary Ovarian Follicles.

  Cinta Zapater, François Chauvigné, Alexander P Scott, Ana Gómez, Ioanna Katsiadaki, Joan Cerdà
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  ABSTRACT: Ovarian growth (vitellogenesis) in most lower vertebrates is mediated by estradiol-17beta (E2) secreted by the follicles in response to the follicle-stimulating hormone (Fsh), whereas oocyte maturation and ovulation is mediated by progestins, such as 17alpha,20beta-dihydroxypregn-4-en-3-one (17,20beta-P), produced in response to the luteinizing hormone (Lh). In teleosts, the follicular synthesis of 17,20beta-P at the time of maturation is primarily due to the up-regulation of P450c17-II (Cyp17a2) and 20beta-hydroxysteroid dehydrogenase (Cbr1) enzymes. Here, we show that follicular cells associated with primary growth (previtellogenic) oocytes of the gilthead seabream also express cyp17a2 and cbr1, in addition to P450c17-I (cyp17a1) and aromatase (cyp19a1), enzymes required for E2 synthesis. Ovaries containing only oogonia and early primary ovarian follicles had a 60-fold higher concentration of 17,20beta-P than ovaries in the succeeding stages; and had a higher expression of cbr1 and the Fsh receptor (fshra). Stimulation of explants of primary follicles in vitro with recombinant piscine Fsh (rFsh), which specifically activates the seabream Fshra, promoted a rapid accumulation of 17,20beta-P, the synthesis being sustained by an external supply of 17alpha-hydroxyprogesterone. In the presence of Cbr1 inhibitors, rFsh-mediated 17,20beta-P production was reduced, with a concomitant increase in testosterone and E2 synthesis. In primary explants, rFsh up-regulated cyp17a2 and cbr1 transcription, and simultaneously down-regulated the cyp17a1 and cyp19a1 steady-state mRNA levels, within 24 h. In contrast, in explants containing vitellogenic follicles, rFsh had no effect on cyp17a2 and cbr1 expression, but increased that of cyp17a1 and cyp19a1. These data suggest a functional Fshra-activated Cyp17a2/Cbr1 steroidogenic pathway in gilthead seabream primary ovarian follicles triggering the production of 17,20beta-P.
  Biology of Reproduction 09/2012; · 4.01 Impact Factor
• Article: Field surveys reveal the presence of anti-androgens in an effluent-receiving river using stickleback-specific biomarkers.

  Ioanna Katsiadaki, Matthew B Sanders, Peter A Henrys, Alexander P Scott, Peter Matthiessen, Tom G Pottinger
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  ABSTRACT: This study was designed to assess whether the removal of endocrine disrupting chemicals (EDCs) and other substances from a Waste Water Treatment Works (WWTW) effluent (receiving water: R. Ray, Swindon, UK) by granular activated carbon (GAC) affected biomarkers of exposure to EDCs [vitellogenin (VTG) and spiggin] in male and female three-spined sticklebacks in the receiving water. A nearby river (R. Ock), with a negligible effluent loading, was used as a control. On each river fish were sampled from four sites on five occasions both before and after remediation of the WWTW effluent. The results show for the first time in a UK field study a clear seasonality of blood VTG concentrations in wild male fish, following closely the VTG profile in female fish from both rivers. VTG levels in male fish from the R. Ray were significantly reduced after the GAC installation. However, VTG levels in males from the control sites also varied significantly across the same period, reducing the significance of this finding. A laboratory exposure to oestradiol (using site-specific lower and upper levels of oestrogenic activity) failed to elevate VTG concentrations in male sticklebacks suggesting that concentrations in the effluent, even prior to remediation, may not have exceeded a critical sensitivity threshold. Most importantly, a significant increase in female kidney spiggin content (a highly specific biomarker of xeno-androgen exposure) occurred in fish in the R. Ray after the GAC installation to levels comparable with those in fish from the control river. The significance of this finding is strengthened by the fact that during the pre-remediation period in the R. Ray, female spiggin levels increased with increasing distance from the WWTW. Our results provide the first in vivo evidence of the presence of anti-androgens in a UK WWTW effluent. To our knowledge this is the first UK-based comprehensive field study on the effects of a WWTW upgrade on biomarkers of EDC exposure using a sentinel fish species and our findings confirm the value of the stickleback as a model species for studying EDCs both in the laboratory and in the wild.
  Aquatic toxicology (Amsterdam, Netherlands) 05/2012; 122-123:75-85. · 3.12 Impact Factor
• Source

  Available from: Ioanna Katsiadaki

  Article: Flow regime affects building behaviour and nest structure in sticklebacks

  Ben J. Rushbrook, Megan L. Head, Ioanna Katsiadaki, Iain Barber
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  ABSTRACT: Animals usually build nests to provide protection, for themselves or their offspring, from adverse environmental conditions. However, different nest structures may be better at providing protection in different environments. The ability to adjust building behaviour and design of nests in response to variation in environmental conditions is therefore likely to be important in determining individual fitness. Here, we look at how the nests of three-spined stickleback (Gasterosteus aculeatus) males differ between still and flowing water conditions. Within flowing water treatments, we find that males select nesting sites with lower than average flow. We also find that nests built in flowing water are smaller and more streamlined than those built in still water. Nests built in flowing water contain more spiggin—an endogenous glycoprotein secreted by nesting males—per gramme of nest material than still water nests, though the absolute spiggin content of nests did not vary with flow regime. These results suggest that male sticklebacks may adjust nest-site selection and nest structure to suit environmental conditions in which they are building. Because flow regime is a factor that is often altered by anthropogenic activities, such as impoundment, channelization and abstraction, this study may also have implications for the conservation of freshwater fish populations. KeywordsNest building-Stickleback-Animal construction-Spiggin-Phenotypic plasticity
  Behavioral Ecology and Sociobiology 04/2012; 64(12):1927-1935. · 3.18 Impact Factor
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  Available from: Ioanna Katsiadaki

  Article: Towards a system level understanding of non-model organisms sampled from the environment: a network biology approach.

  Tim D Williams, Nil Turan, Amer M Diab, Huifeng Wu, Carolynn Mackenzie, Katie L Bartie, Olga Hrydziuszko, Brett P Lyons, Grant D Stentiford, John M Herbert, Joseph K Abraham, Ioanna Katsiadaki, Michael J Leaver, John B Taggart, Stephen G George, Mark R Viant, Kevin J Chipman, Francesco Falciani
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  ABSTRACT: The acquisition and analysis of datasets including multi-level omics and physiology from non-model species, sampled from field populations, is a formidable challenge, which so far has prevented the application of systems biology approaches. If successful, these could contribute enormously to improving our understanding of how populations of living organisms adapt to environmental stressors relating to, for example, pollution and climate. Here we describe the first application of a network inference approach integrating transcriptional, metabolic and phenotypic information representative of wild populations of the European flounder fish, sampled at seven estuarine locations in northern Europe with different degrees and profiles of chemical contaminants. We identified network modules, whose activity was predictive of environmental exposure and represented a link between molecular and morphometric indices. These sub-networks represented both known and candidate novel adverse outcome pathways representative of several aspects of human liver pathophysiology such as liver hyperplasia, fibrosis, and hepatocellular carcinoma. At the molecular level these pathways were linked to TNF alpha, TGF beta, PDGF, AGT and VEGF signalling. More generally, this pioneering study has important implications as it can be applied to model molecular mechanisms of compensatory adaptation to a wide range of scenarios in wild populations.
  PLoS Computational Biology 08/2011; 7(8):e1002126. · 5.22 Impact Factor
• Article: Assessment of reproductive biomarkers in three-spined stickleback (Gasterosteus aculeatus) from sewage effluent recipients.

  Carina Björkblom, Noora Mustamäki, Per-Erik Olsson, Ioanna Katsiadaki, Tom Wiklund
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  ABSTRACT: The aim of this study was to examine the occurrence of endocrine disruption close to sewage treatment plant effluent discharges along the Finnish Baltic Sea coast using a set of reproductive biomarkers present in adult three-spined stickleback (Gasterosteus aculeatus). Possible variation and sensitivity of the biomarkers during an entire reproductive period were also examined. The analysis of vitellogenin (VTG) for estrogenic activity and spiggin for androgenic activity, together with histopathological analysis indicated that sticklebacks were exposed to estrogenic loads sufficient to cause inappropriate production of VTG and to disrupt normal testicular structure in adult male sticklebacks. No androgenic disruption was observed. The results emphasize the need of a combination of several reproductive biomarkers in fish and repeated sampling for the detection of potential endocrine modulating substances under field condition. © 2011 Wiley Periodicals, Inc. Environ Toxicol, 2011.
  Environmental Toxicology 06/2011; · 2.41 Impact Factor