title: Identification of molecular markers in pectoral fin to predict artificial maturation of female European eels (Anguilla anguilla).
abstract: The European eel is a critically endangered species that cannot be reproduced in captivity yet. Artificial maturation of female European eels can be achieved via a laborious and expensive procedure, including weekly injections with pituitary extracts for up to 6 months. The success rate is highly variable and a minimally invasive method for early selection of responsive eels would prevent the unnecessary and lengthy treatment of non-responding individuals. Since sexual maturation of European eels is accompanied by morphological changes of the pectoral fin, we examined whether fin could be used to monitor the response to the hormone treatment. Farmed eels were subjected to weekly injections with pituitary extracts and representative groups were sampled at 0 and 14-18 weeks of hormone treatment. Responders and non-responders were identified based on the gonado-somatic index. Transcriptomes of pectoral fin samples obtained at the start and end of the trial were mapped using Illumina RNAseq. Responders showed 384 and non-responders only 54 differentially expressed genes. Highly stringent selection based on minimum expression levels and fold-changes and a manual re-annotation round yielded 23 up-regulated and 21 down-regulated maturation marker genes. The up-regulated markers belong to five categories: proteases, skin/mucus structural proteins, steroid hormone signaling, tyrosine/dopamine metabolism and lipid metabolism. The down-regulated markers are either blood markers or lectin-related genes. In conclusion, pectoral fin transcriptomes are a rich source of indicator markers for monitoring hormone induced sexual maturation of female European eels. In addition, these markers provide important new insight into several fundamental processes in eel biology.
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: 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. Electronic address: E.Burgerhout@biology.leidenuniv.nl.
authors.forename: Erik
authors.initials: E
authors.lastname: Burgerhout
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: ozupek@zfscreens.com.
authors.forename: Hulya
authors.initials: H
authors.lastname: Ozupek
authors.affiliation: ZF-screens B.V., J.H. Oortweg 19, 2333 CH Leiden, The Netherlands. Electronic address: koelma@zfscreens.com.
authors.forename: Nynke
authors.initials: N
authors.lastname: Tuinhof-Koelma
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: jongraadsen@zfscreens.com.
authors.forename: Susanne A
authors.initials: SA
authors.lastname: Jong-Raadsen
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: 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: GE
authors.lastname: van den Thillart
mesh_terms: D000811:Anguilla / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D000818:Animals; D015415:Biomarkers / Q000032:analysis*; D015153:Blotting, Western; D005260:Female; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation / Q000187:drug effects*; D059014:High-Throughput Nucleotide Sequencing; D006728:Hormones / Q000494:pharmacology*; D010902:Pituitary Gland / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics; D060888:Real-Time Polymerase Chain Reaction; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012741:Sexual Maturation / Q000187:drug effects / Q000502:physiology*
chemical_list: D015415:Biomarkers; D006728:Hormones; D012333:RNA, Messenger
keywords: Artificial maturation; European eel; Minimally invasive; Pectoral fin; Predictive markers