title: Changes in ovarian gene expression profiles and plasma hormone levels in maturing European eel (Anguilla anguilla); Biomarkers for broodstock selection.
abstract: Complete sexual maturation of European eels (Anguilla anguilla) in captivity can only be achieved via injections with gonadotropins. For female eels this procedure takes 4-6months and the response ranges from "unresponsive" to final maturation and ovulation. Reproductive success could be significantly increased via early selection of responders based on predictive markers and minimally invasive sampling methods. To get a better understanding of the genetic background of ovarian maturation of the European eel we performed a pilot deep-sequencing transcriptome analysis of ovarian tissue derived from a yellow eel, a prepubertal silver eel and a post-spawning matured eel. Two key players in steroidogenesis were strongly correlated with advanced sexual maturation, namely P450c17 and liver receptor homolog-1, suggesting that blood plasma steroids might qualify as minimally invasive markers for early detection of responders. Since the predictive value of plasma sex steroid levels for final maturation of the European eel had not yet been carefully examined, we performed an extensive artificial maturation trial. Farmed silver eels were treated with pituitary extracts and sampled at multiple time intervals. Expression of steroidogenesis-related genes in ovarian tissue of responding and non-responding eels after four weekly injections with pituitary extract was compared using a custom-built microarray and RNAseq. Increased expression of 17β-hsd1 was strongly linked to sexual maturation. Blood plasma levels of sex steroids were measured using ELISAs. We show that a 2.5-fold increase in blood-plasma estradiol level after 4 weekly pituitary extract injections is a strong predictor of final sexual maturation of female European eel.
authors.affiliation: Institute of Biology, Leiden University, P.O. Box 9505, 2300 RA Leiden, The Netherlands. Electronic address: erik.burgerhout@nofima.no.
authors.forename: Erik
authors.initials: E
authors.lastname: Burgerhout
authors.affiliation: Institute of Biology, Leiden University, P.O. Box 9505, 2300 RA Leiden, The Netherlands. Electronic address: y.minegishi@m.tohoku.ac.jp.
authors.forename: Yuki
authors.initials: Y
authors.lastname: Minegishi
authors.affiliation: ZF-screens B.V., J.H. Oortweg 19, 2333 CH Leiden, The Netherlands. Electronic address: brittijn@zfscreens.com.
authors.forename: Sebastiaan A
authors.initials: SA
authors.lastname: Brittijn
authors.affiliation: Institute of Biology, Leiden University, P.O. Box 9505, 2300 RA Leiden, The Netherlands. Electronic address: wijze@viroclinics.com.
authors.forename: Danielle L
authors.initials: DL
authors.lastname: de Wijze
authors.affiliation: ZF-screens B.V., J.H. Oortweg 19, 2333 CH Leiden, The Netherlands. Electronic address: c.v.henkel@biology.leidenuniv.nl.
authors.forename: Christiaan V
authors.initials: CV
authors.lastname: Henkel
authors.affiliation: ZF-screens B.V., J.H. Oortweg 19, 2333 CH Leiden, The Netherlands. Electronic address: jansen@zfscreens.com.
authors.forename: Hans J
authors.initials: HJ
authors.lastname: Jansen
authors.affiliation: Institute of Biology, Leiden University, P.O. Box 9505, 2300 RA Leiden, The Netherlands. Electronic address: h.p.spaink@biology.leidenuniv.nl.
authors.forename: Herman P
authors.initials: HP
authors.lastname: Spaink
authors.affiliation: ZF-screens B.V., J.H. Oortweg 19, 2333 CH Leiden, The Netherlands. Electronic address: dirks@zfscreens.com.
authors.forename: Ron P
authors.initials: RP
authors.lastname: Dirks
authors.affiliation: Institute of Biology, Leiden University, P.O. Box 9505, 2300 RA Leiden, The Netherlands; ZF-screens B.V., J.H. Oortweg 19, 2333 CH Leiden, The Netherlands. Electronic address: g.van.den.thillart@biology.leidenuniv.nl.
authors.forename: Guido E E J M
authors.initials: GEEJM
authors.lastname: van den Thillart
mesh_terms: D000811:Anguilla / Q000097:blood / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D015415:Biomarkers / Q000378:metabolism; D005260:Female; D020869:Gene Expression Profiling; D059014:High-Throughput Nucleotide Sequencing; D010053:Ovary / Q000378:metabolism*; D010902:Pituitary Gland / Q000378:metabolism; D018160:Receptors, Cytoplasmic and Nuclear / Q000235:genetics / Q000378:metabolism; D012741:Sexual Maturation / Q000502:physiology*; D013254:Steroid 17-alpha-Hydroxylase / Q000235:genetics / Q000378:metabolism; D059467:Transcriptome
chemical_list: D015415:Biomarkers; D018160:Receptors, Cytoplasmic and Nuclear; D013254:Steroid 17-alpha-Hydroxylase
keywords: Artificial maturation; European eel; Minimally invasive; Predictive markers; Steroidogenesis; Transcriptome profiling