To view the fulltext, please log in
To view the pdf, please log in
New data are presented on the sex chromosomes of the fish species Eigenmannia virescens (Gymnotiformes, Sternopygidae). A new finding, involving the occurrence of ZZ/ZW sex chromosomes, is described in specimens sampled from the São Francisco and Amazon river basins in Brazil. All individuals had a chromosome number of 2n = 38. The homologs of the sex chromosome pair from the São Francisco river basin sample differed only in their morphology, while those from the Amazonian sample differed both in morphology and heterochromatin pattern. A possible model for the evolution of the sex chromosomes in E. virescens is proposed, including data from populations from the Paraná (Brazil) river basin, in which male heterogamety has already been described. The occurrence of different sex chromosome systems in species and populations of the neotropical freshwater fish fauna is discussed.
Copyright / Drug Dosage
Copyright: All rights reserved. No part of this publication may be translated into other languages, reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying, recording, microcopying, or by any information storage and retrieval system, without permission in writing from the publisher or, in the case of photocopying, direct payment of a specified fee to the Copyright Clearance Center.
Drug Dosage: The authors and the publisher have exerted every effort to ensure that drug selection and dosage set forth in this text are in accord with current recommendations and practice at the time of publication. However, in view of ongoing research, changes in goverment regulations, and the constant flow of information relating to drug therapy and drug reactions, the reader is urged to check the package insert for each drug for any changes in indications and dosage and for added warnings and precautions. This is particularly important when the recommended agent is a new and/or infrequently employed drug.
Disclaimer: The statements, opinions and data contained in this publication are solely those of the individual authors and contributors and not of the publishers and the editor(s). The appearance of advertisements or/and product references in the publication is not a warranty, endorsement, or approval of the products or services advertised or of their effectiveness, quality or safety. The publisher and the editor(s) disclaim responsibility for any injury to persons or property resulting from any ideas, methods, instructions or products referred to in the content or advertisements.
- Almeida-Toledo LF, Daniel-Silva MFZ, Lopes CE, Toledo-Filho SA: Sex chromosome evolution in fish. II. Second occurrence of an X1X2Y sex chromosome system in Gymnotiformes. Chrom Res 8:335–340 (2000a).
- Almeida-Toledo LF, Foresti F: Morphologically differentiated sex chromosomes in neotropical freshwater fish. Genetica 111:91–100 (2001a).
- Almeida-Toledo LF, Foresti F, Daniel-Silva MFZ, Toledo-Filho SA: Sex chromosome evolution in fish: the formation of the neo-Y chromosome in Eigenmannia (Gymnotiformes). Chromosoma 109:197–200 (2000b).
- Almeida-Toledo LF, Foresti F, Péquignot EV, Daniel-Silva MFZ: XX:XY sex chromosome system with X heterochromatinization: an early stage of sex chromosome differentiation in the neotropic electric eel Eigenmannia virescens. Cytogenet Cell Genet 95:73–78 (2001b).
- Bertollo LAC, Fontes MS, Fenocchio AS, Cano J: The X1X2Y sex chromosome system in the fish Hoplias malabaricus. I. G-, C-, and chromosome replication banding. Chrom Res 5:493–499 (1997).
- Born GG, Bertollo LAC: An XX/XY sex chromosome system in a fish species, Hoplias malabaricus, with a polymorphic NOR-bearing X chromosome. Chrom Res 8:111–118 (2000).
- Campos da Paz R: Sistemática e Taxonomia dos Peixes Elétricos das Bacias dos Rios Paraguai, Paraná e São Francisco, com Notas sobre Espécies Presentes em Rios Costeiros do Leste do Brasil. Tese de Doutorado, Universidade de São Paulo, São Paulo, SP, Brazil (1997).
- Centofante L, Bertollo LAC, Moreira-Filho O: A ZZ/ZW sex chromosome system in a new species of the genus Parodon (Pisces, Parodontidae). Caryologia 55:139–150 (2002).
- Foresti F: Estudos Cromossômicos em Gymnotiformes (Pisces, Ostariophysi). Tese de Livre-Docência, Universidade Estadual Paulista, Botucatu, SP, Brazil (1987).
- Howell WM, Black DA: Controlled silver-staining of nucleolus organizer region with a protective colloidal developer: a 1-step method. Experientia 36:1014–1016 (1980).
- Knudsen EI: Behavioral thresholds to electric signals in high frequency electric fish. J comp Physiol 91:333–353 (1974).
- Nanda I, Volff JN, Weis S, Körting C, Froschauer A, Schmid M, Schartl M: Amplification of long terminal repeat-like element on the Y chromosome of the platyfish, Xiphophorus maculatus. Chromosoma 109:173–180 (2000).
- Nelson JS: Fishes of the World, 3rd Ed (John Wiley & Sons, New York 1994).
- Sumner AT: A simple technique for demonstrating centromeric heterochromatin. Expl Cell Res 75:304–306 (1972).
- Volff JN, Schartl M: Variability of genetic sex determination in poeciliid fishes. Genetica 111:101–110 (2001).