Researchers from Osaka University and the National Institute for Basic Biology, Japan, have found a highly significant connection between the molecular mechanisms underlying genetic and environmental sex determination. The scientists report in the open-access journal PLoS Genetics the identification of a gene responsible for the production of males during environmental sex determination in the crustacean Daphnia.
Ways in which an individual organism's sex is determined are diverse among animal lineages and can be broadly divided into two major categories: genetic and environmental. In genetic sex determination (GSD), sex-specific differentiation results from intrinsic genetic differences between males and females, whereas environmental sex determination (ESD) relies upon environmental signals to induce male or female sex determination. In contrast to GSD models, the genetics of ESD organisms are poorly understood.
The researchers cloned Doublesex (Dsx) genes from Daphnia magna, a freshwater brachiopod crustacean that clones itself to produce males in response to certain environmental cues. The Dsx genes play an important role in controlling sexual differences in organisms using GSD such as nematodes, insects, and vertebrates. Knocking out one particular Dsx gene, DapmaDsx1, in male embryos resulted in the production of female traits including ovarian maturation, whereas ectopic expression of DapmaDsx1 in female embryos resulted in the development of male-like phenotypes.
The researchers infer that there is an ancient, previously unidentified link between genetic and environmental sex determination. This study was confined only to the role of Dsx in ESD, so it would be highly desirable to establish the link between the environmental signal and Dsx expression. However, this work lends support to the "Doublesex hypothesis" of sex determination, in which many different sorts of upstream regulatory pathways could converge on Dsx-family genes, which would serve as the basis of sexual differentiation mechanisms across the animal kingdom.
FINANCIAL DISCLOSURE: This study was partly supported through grants from Grants-in-Aid from Ministry of Education, Culture, Sport, Science, and Technology (to HW), grants from Ministry of the Environment of Japan, and a grant of Long-Range Research Initiative (LRI) by Japan Chemical Industry Association (JCIA) (to TI). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
COMPETING INTERESTS: The authors have declared that no competing interests exist.
CITATION: Kato Y, Kobayashi K, Watanabe H, Iguchi T (2011) Environmental Sex Determination in the Branchiopod Crustacean Daphnia magna: Deep Conservation of a Doublesex Gene in the Sex-Determining Pathway. PLoS Genet 7(3): e1001345. doi:10.1371/journal.pgen.1001345
PLEASE ADD THIS LINK TO THE FREELY AVAILABLE ARTICLE IN ONLINE VERSIONS OF YOUR REPORT (the link will go live when the embargo ends): http://www.plosgenetics.org/article/info:doi/10.1371/journal.pgen.1001345
CONTACT: Taisen Iguchi
This press release refers to an upcoming article in PLoS Genetics. The release is provided by journal staff, or by the article authors and/or their institutions. Any opinions expressed in this release or article are the personal views of the journal staff and/or article contributors, and do not necessarily represent the views or policies of PLoS. PLoS expressly disclaims any and all warranties and liability in connection with the information found in the releases and articles and your use of such information.
About PLoS Genetics
PLoS Genetics (http://www.plosgenetics.org) reflects the full breadth and interdisciplinary nature of genetics and genomics research by publishing outstanding original contributions in all areas of biology. All works published in PLoS Genetics are open access. Everything is immediately and freely available online throughout the world subject only to the condition that the original authorship and source are properly attributed. Copyright is retained by the authors. The Public Library of Science uses the Creative Commons Attribution License.
About the Public Library of Science
The Public Library of Science (PLoS) is a non-profit organization of scientists and physicians committed to making the world's scientific and medical literature a freely available public resource. For more information, visit http://www.plos.org.
AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert! system.