during microsatellite selection is only a minor con- tributor to the variation observed. doi:10.1016/j.aquaculture.2007.07.196 The use of laser microdissection coupled with semiquantitave PCR to study cell-specific gene expression during European sea bass (Dicentrarchus labrax) spermatogenesis J. Viñas, L. Navarro, A. Mechaly, F. Piferrer Institut de Ciències del Mar Consejo Superior de Investigaciones Científicas 08003, Barcelona, Spain The European sea bass (Dicentrarchus labrax), a gonochoristic marine teleost, is the subject of both basic and applied research. A major disadvantage of sea bass culture is the presence of precocious males that mature at the first year of life. One of the key points for understanding the molecular basis of male precocity is the quantification of gene expression in specific cell populations. We optimized a newly developed techni- que, Laser Microdissection Pressure Catapulting, coupled with semiquantitative PCR that allows deter- mining the precise expression pattern of genes in specific cell populations throughout testis development. We quantified the expression pattern of several genes during the germ cell line progression from spermatogo- nia to spermatozoa that were already cloned in the sea bass. The studied genes were: androgen receptor (AR), P450 gonadal aromatase, vasa, and oestrogen receptors (ERα, ERβ1 and ERβ2). Knowledge of the specific expression levels of these genes will be useful to investigate their role in male spermatogenesis and their possible implications in the phenomenon of male precocity in sea bass aquaculture. doi:10.1016/j.aquaculture.2007.07.197 A second generation linkage map of European sea bass F.A.M.J. Volckaert a , C. Batargias b , D. Chatziplis c , D. Chistiakov a, * , Y. Guo d , C.S. Haley d , B. Hellemans a , G. Kotoulas e , A. Law d , A. Libertini f , B.J. McAndrew g , C. Tsigenopoulos e , H.A. Whitaker g a Laboratory of Aquatic Ecology, Katholieke Universi- teit Leuven, Ch. Deberiotstraat 32, Leuven B-3000, Belgium b Nireus Chios Aquaculture S.A., Kardamila, Chios 82 300, Greece c Laboratory of Farm Animal Genetics and Breeding, Department of Animal Production, Aristotle University of Thessaloniki, Thessaloniki 54006, Greece d Roslin Institute (Edinburgh), Division of Genetics and Biometry, Roslin, Midlothian EH25 9PS, UK e Hellenic Centre for Marine Research, Institute of Marine Biology of Crete, Department of Genetics and Molecular Biotechnology, P.O. Box 2214, Iraclio, Greece f Institute of Marine Sciences, Consiglio Nazionale delle Ricerche, Riva 7 Martiri, 1364/A, Venezia I- 30122, Italy g Institute of Aquaculture, Genetics and Reproduction Research Group, University of Stirling, Stirling FK9 4LA, Scotland, UK *Current address: Department of Pathology and Laboratory Medicine, University of Cincinnati Medical Center, 231 Albert Sabin Way, Cincinnati, OH 45267- 0529, USA. The BASSMAP consortium, funded by the European Union, has been set up to improve the genomic resources of European sea bass (Dicentrarchus labrax) and to serve the aquaculture community. The specific aim is to locate genes of known function on the physical map and to compare specific regions among perciforms. A first generation map including 162 microsatellite markers and 25 linkage groups has been published (Chistiakov et al., 2005, Genetics 170: 1821–1826). A second genera- tion linkage map including in total 369 polymorphic microsatellite and AFLP markers includes 34 linkage groups (2n =24). The total sex-averaged map length measures now 1506 cM (1166 cM in males and 1553 cM in females). The map includes twenty nine Expressed Sequence Tags or genes. Fifty eight markers remain unlinked (11 microsatellites and 47 AFLPs). doi:10.1016/j.aquaculture.2007.07.198 Genomic resources for the aquaculture of European sea bass F.A.M.J. Volckaert a , C. Batargias b , F. Bonhomme c , A. Canario d , D. Chistiakov a, * , J.V. Choudhuri e , F. Galibert f , A. Georgoudis g , C.S. Haley h , B. Hellemans a , H. Kuhl i , G. Kotoulas j , A. Law h , A. Libertini k , A. Magoulas j , B.J. McAndrew l , R. Reinhardt i , F. Senger f , E. Souche a , C. Tsigenopoulos j , H.A. Whitaker l S316 Abstracts / Aquaculture 272S1 (2007) S238–S321