Steroid Profiles in Cultured Female Jundia ´, the Siluridae Rhamdia quelen (Quoy and Gaimard, Pisces Teleostei), during the First Reproductive Cycle Leonardo J. G. Barcellos, * ,1 Guillermo F. Wassermann, * Alexander P. Scott, † Viviane M. Woehl, * Rosmari M. Quevedo, ‡ Istva ´n Ittze ´s, ‡ Marta Helena Krieger, § and Francisco Lulhier ¶ * Laboratory of Experimental Endocrinology, Federal University of the State of Rio Grande do Sul (UFRGS), Instituto de Cie ˆncias Ba ´sicas da Sau ´de, Rua Sarmento Leite, 500, Departamento de Fisiologia, sala 212, laborato ´rio 7, CEP 90050- 170, Porto Alegre, RS, Brazil; ‡ Laboratory of Aquaculture, University of Passo Fundo (UPF), Campus Universita ´rio do Bairro Sa ˜o Jose ´, Caixa Postal 611, CEP 99001-970; § Institute of Biology, State University of Campinas, UNICAMP, Cidade Universita ´ria Zeferino Vaz, Caixa Postal 6109, CEP 13083-970 — Distrito de Bara ˜o Geraldo, Campinas, SP, Brazil; † Center for Environment, Fisheries and Aquaculture Science, Pakefield Road, Lowestoft, Suffolk, NR33 0HT, United Kingdom; and ¶ Laborato ´rio de Radioimunoenssaio, Hospital das Clı´nicas, Federal University of the State of Rio Grande do Sul, Porto Alegre, RS, Brazil Accepted December 20, 2000 The jundia ´ Rhamdia quelen (Quoy and Gaimard) is a te- leost species from the Siluridae family and is an impor- tant species for aquaculture in temperate and subtropical climates. Gonad and blood tissue samples were taken from cultured jundia ´ females between 1998 and 1999. Plasma concentrations of 17 -estradiol (E 2 ), testosterone (T), 11-ketotestosterone (11-KT), 17-hydroxy-4-preg- nene-3,20-dione (17-P), 17,20 -dihydroxy-4-pregnen-3- one (17,20 -P), and 17,20 ,21-trihydroxy-4-pregnen-3- one (20 -S) were measured by radioimmunoassay and potential correlations with the stage of oogenesis and sexual maturation examined. During the experimental period two spawning episodes were observed. Plasma concentrations of E 2 increased progressively during oo- cyte development, simultaneously with the appearance of yolk vesicles and increasing amounts of deposited yolk. In female jundia ´, the T peak occurred in October and was coincident with the peak in gonadosomatic index. Two distinct peaks of progestogens were detected, corre- sponding to the two spawning episodes, suggesting that one or more of these steroids might act as the “matura- tional-inducing steroid” in jundia ´. Unusually large amounts of 11-KT were also measured in the plasma of mature jundia ´ females. The identity of 11-KT was con- firmed by thin-layer chromatography. Although the pro- files of the other steroids are compatible with the roles proposed for the action of these hormones in other te- leosts, the role of 11-KT, normally found only in males, is unknown. © 2001 Academic Press Key Words: 17 -estradiol; C21 steroids; Rhamdia quelen; testosterone; 11-ketotestosterone. INTRODUCTION The jundia ´(Rhamdia quelen, Quoy and Gaimard) is an endemic species in South America. It can withstand cold winters and can grow fast in the summer. In aquaculture systems, at a density of two to four fish per square meter, it will reach 600 – 800 g body weight in 8 months. It is a suitable species for fish production 1 To whom correspondence should be addressed at Prac ¸a das Nac ¸o ˜es Unidas, 61, Apto 801 - CEP 90690-430, Porto Alegre - RS - Brazil. Fax: +55 51 316.3302. E-mail: leohelo@cpovo.net. General and Comparative Endocrinology 121, 325–332 (2001) doi:10.1006/gcen.2001.7603, available online at http://www.idealibrary.com on 0016-6480/01 $35.00 Copyright © 2001 by Academic Press All rights of reproduction in any form reserved. 325