Aquaculture Research, 2010, 41, e1^e7 doi:10.1111/j.1365-2109.2009.02463.x Review Article A review of sex determination and searches for sex-specific markers in sturgeon Saeed Keyvanshokooh1 & Ahmad Gharaei2 Department of Fisheries, Faculty of Marine Natural Resources, Khorramshahr University of Marine Science and Technology, Khorramshahr, Khouzestan, Iran Department of Fisheries, Faculty of Natural Resources, University of Zabol, Zabol, Sistan & Blouchestan, Iran Correspondence: S Keyvanshokooh, Department of Fisheries, Faculty of Marine Natural Resources, Khorramshahr University of Marine Science and Technology, Khorramshahr, Khouzestan, Iran E-mail: keyvan56@yahoo.com Abstract The availability of monosex populations of caviarproducing female sturgeon would considerably enhance the economic viability of domestic caviar production systems However, it is not possible to distinguish males from females by morphological characters at larval, juvenile and even adult stages The mechanism of sex determination in sturgeons is poorly understood, and to date no sex-speci¢c markers in sturgeon have been reported This review concentrates on the methodologies used to elucidate the mode of sex determination in sturgeon species and provides information on the molecular tools used to determine genetic sex markers Keywords: sturgeon, sex determination, sex marker, genomics, proteomics Introduction Sturgeon species (FamilyAcipenseridae) belonging to the order Acipenseriformes, are primitive ¢shes (Bemis, Findies & Grande 1997) that evolved approximately 250 million years ago Sturgeon populations are declining worldwide due to over¢shing, pollution and habitat degradation (Birstein 1993; Billard & Lecointre 2001) Production of sturgeon for meat or caviar increasingly has to rely on aquaculture (Logan, Johnston & Doroshov 1995) As sturgeon species are highly prized for their caviar, females are more valuable than males From an aquacultural perspective, it is important that the sex of sturgeon be identi¢ed in r 2010 The Authors Journal Compilation r 2010 Blackwell Publishing Ltd the early stage of development, so that males can be reserved for meat and females for caviar production None of the sturgeon species exhibit external sexual dimorphism, and the absence of external markers for sexing has encouraged the search for a practical technique for gender identi¢cation Blood plasma sex steroid levels in sturgeon remain low until the beginning of gonadal development (Doroshov, Moberg & Van Eenennaam 1997) Although an examination of plasma steroids could be used to sex sturgeon (Webb, Feist, Foster, Schreck & Fitzpatrick 2002), these steroid indicators are in£uenced by age, husbandry conditions and water temperature (Feist,Van Eenennaam, Doroshov, Schreck, Schneider & Fitzpatrick 2004) The current diagnostic technique for sex identi¢cation in these sexually monomorphic species requires surgical biopsy of sexually di¡erentiated gonads (Doroshov et al 1997) Although survival rate is nearly100%, this surgery is invasive (Feist et al 2004) and non-invasive procedures are needed for sexing sturgeon The di¡erent techniques that have been used to elucidate the sex-determining system and to identify sex-speci¢c markers in sturgeon are the subject of this review Elucidation of sex-determining mechanism in sturgeon Sex determination is the genetic or environmental process by which the sex (male or female) of an individual is established in a simple binary fate decision (Penman & Piferrer 2008) Fish use a wide array of mechanisms for sex determination (reviewed by e1 Sex determination in sturgeon S Keyvanshokooh & A Gharaei Devlin & Nagahama 2002) Many species use genetic systems that determine sex at fertilization A number of ¢sh species use intrinsic clues provided by behavioural interactions among conspeci¢cs, some use changes in environmental factors such as temperature, season or year class, whereas in some cases, sex may also be determined by genetic^environmental interactions Intersexuality (ovotestis) is a condition whereby an individual possesses oocytes or di¡erent stages of spermatogonia, at varying degrees of development, within the normal gonad of the opposite gender (i.e spermatocytes in the ovary or oocytes in the testis) (Jackson, Hurvitz, Din, Goldberg, Pearlson, Degani & Levavi-Sivan 2006) Hermaphroditism in sturgeon is not a normal situation, and the few cases of intersexuality that have been reported in wild sturgeon have all been from polluted habitats (Chapman, Van Eenennaam & Doroshov 1996; Van Eenennaam & Doroshov 1998; Harshbarger, Co¡ey & Young 2000) In addition, the sex ratio in adult populations of sturgeon has been 1[...]... review Aquaculture 34, 115^143 r 2010 The Authors Journal Compilation r 2010 Blackwell Publishing Ltd, Aquaculture Research, 41, e8^e19 Aquaculture Research, 2010, 41, e8^e19 Live prey Ârst feeding regimes for H hippocampus juveniles F Otero-Ferrer et al Waterstrat P.R (1999) Induction and recovery from anesthetic in channel catÂsh Ictalurus punctatus Ângerlings exposed to clove oil Journal ofWorld Aquaculture. .. ingredients and their eĂects in Âsh Aquaculture 1 99, 197^227 Gatlin D.B III, Barrows F.T., Brown P., Dabrowski K., Gaylord T.G., Hardy R.W., Herman E., Hu G., Krogdahl ., Nelson R., Overturf K., Rust M., Sealey W., Skonberg D., Souza r 2010 The Authors Journal Compilation r 2010 Blackwell Publishing Ltd, Aquaculture Research, 41, e20^e30 Aquaculture Research, 2010, 41, e20^e30 E.J., Stone D., Wilson... fed with commercial yeast (Saccharomyces cerevisiae) and enriched with DHA pro- r 2010 The Authors Journal Compilation r 2010 Blackwell Publishing Ltd, Aquaculture Research, 41, e8^e19 Aquaculture Research, 2010, 41, e8^e19 Live prey Ârst feeding regimes for H hippocampus juveniles F Otero-Ferrer et al tein-Selco (INVE Aquaculture, Dendermonde, Belgium) following the standard protocols of ICCM (Roo,... UniversiteÔ de Bordeaux, France, 379pp Bull C.D 2002 Seahorse Husbandry in Public Aquaria John G Shedd Aquarium, Chicago, IL, USA, 55pp r 2010 The Authors Journal Compilation r 2010 Blackwell Publishing Ltd, Aquaculture Research, 41, e8^e19 Aquaculture Research, 2010, 41, e8^e19 Live prey Ârst feeding regimes for H hippocampus juveniles F Otero-Ferrer et al Casey S., Hall H., Stanley H & Vincent A (2004)... problem, in RA treatment (b) Figure 2 Daily average mortality observed in each treatment, RA (D) and A (O), during the experiment e12 r 2010 The Authors Journal Compilation r 2010 Blackwell Publishing Ltd, Aquaculture Research, 41, e8^e19 Aquaculture Research, 2010, 41, e8^e19 Live prey Ârst feeding regimes for H hippocampus juveniles F Otero-Ferrer et al Figure 3 Measurements of seahorse juvenilessnout... Syngnathidae) Aquaculture 190, 377^388 Woody C.A., Nelson J & Ramstad K (2002) Clove oil as an anaesthetic for adult sockeye salmon: Âeld trials Journal of Fish Biology 60, 340^347 Zar J.H (1996) Biostatistical Analysis, 3rd edn Prentice-Hall, Upper Saddle River, NJ, USA, 662pp r 2010 The Authors Journal Compilation r 2010 Blackwell Publishing Ltd, Aquaculture Research, 41, e8^e19 e19 Aquaculture Research, 2010, ... nitrogen-free extracts 51000 (CP1CL1CA) in limits recommended for Senegalese sole Fish were exposed to an artiÂcial photoperiod of 12 h light r 2010 The Authors Journal Compilation r 2010 Blackwell Publishing Ltd, Aquaculture Research, 41, e20^e30 Aquaculture Research, 2010, 41, e20^e30 Development of a plant-protein rich diet for sole J M G Silva et al Table 2 Indispensable amino acids (IAA, g16 g 1 N) present... hydrolysis, and hence the r 2010 The Authors Journal Compilation r 2010 Blackwell Publishing Ltd, Aquaculture Research, 41, e20^e30 e23 Development of a plant-protein rich diet for sole J M G Silva et al values reported for these AAs (Asx and Glx) represent the sum of the respective amide and acid Resulting peaks were analysed using the BREEZE software (Waters) Aquaculture Research, 2010, 41, e20^e30 body composition... diets while lipid intake was signiÂcantly lower in Âsh fed the test diet (1.9 vs 2.4 g kg 1 ABWday 1), as a reÊection of the lower li- r 2010 The Authors Journal Compilation r 2010 Blackwell Publishing Ltd, Aquaculture Research, 41, e20^e30 Aquaculture Research, 2010, 41, e20^e30 Development of a plant-protein rich diet for sole J M G Silva et al Table 3 Growth performance, total feed oĂered and nutrient... Additionally, instead of feeding by hand, Âsh were fed by automatic feeders during 24 h Data on growth and protein gain in the acceptance trial r 2010 The Authors Journal Compilation r 2010 Blackwell Publishing Ltd, Aquaculture Research, 41, e20^e30 Aquaculture Research, 2010, 41, e20^e30 (Table 3) should be interpreted with caution as this was a very short trial (4 weeks) particularly designed to test the acceptability