Academic Journal
Evolution of the gene network underlying gonadogenesis in turtles with temperature-dependent and genotypic sex determination
| العنوان: | Evolution of the gene network underlying gonadogenesis in turtles with temperature-dependent and genotypic sex determination |
|---|---|
| المؤلفون: | Valenzuela, Nicole |
| بيانات النشر: | Oxford University Press |
| سنة النشر: | 2008 |
| المجموعة: | HighWire Press (Stanford University) |
| مصطلحات موضوعية: | Reptile Genomics and Evolutionary Genetics |
| الوصف: | The evolution of sex determination has long fascinated biologists, as it has paramount consequences for the evolution of a multitude of traits, from sex allocation to speciation and extinction. Explaining the diversity of sex-determining systems found in vertebrates (genotypic or GSD and temperature-dependent or TSD) requires a comprehensive and integrative examination from both a functional and an evolutionary perspective. Particularly revealing is the examination of the gene network that regulates gonadogenesis. Here, I review some advances in this field and propose some additional hypotheses about the composition of the gene network underlying sexual development, the functional links among some of its elements and their evolution in turtles. I focus on several pending questions about: (1) What renders TSD systems thermo-sensitive? (2) Is there one developmentally conserved or multiple TSD mechanisms? (3) Have evolutionarily derived GSD species lost all ancestral thermal-sensitivity? New data are presented on embryonic expression of Dax1 (the dosage-sensitive sex-reversal adrenal hypoplasia congenital on the X chromosome gene in the turtles Chrysemys picta (TSD) and Apalone mutica (GSD). No differential Dax1 expression was detected in C. picta at any of the stages examined, consistent with reports on two other TSD turtles and alligators. Notably, significantly higher Dax1 expression was found at 30°C than at 25°C at stage 15 in A. mutica (GSD), likely caused by Wt1's identical expression pattern previously reported. Because Sf1 is an immediate downstream target of Dax1 and its expression is not affected by temperature, it is proposed that Sf1 renders Dax1's differential signal ineffective to induce biased sex ratios in A. mutica , as previously proposed for Wt1's thermosensitive expression. Thus, it is hypothesized that Sf1 plays a major role in the lack of response of sex ratio to temperature of A. mutica , and may function as a sex-determining gene in this GSD species. These and previous data permit ... |
| نوع الوثيقة: | text |
| وصف الملف: | text/html |
| اللغة: | English |
| Relation: | http://icb.oxfordjournals.org/cgi/content/short/48/4/476; http://dx.doi.org/10.1093/icb/icn031 |
| DOI: | 10.1093/icb/icn031 |
| الاتاحة: | http://icb.oxfordjournals.org/cgi/content/short/48/4/476 https://doi.org/10.1093/icb/icn031 |
| Rights: | Copyright (C) 2008, The Society for Integrative and Comparative Biology |
| رقم الانضمام: | edsbas.33B731A |
| قاعدة البيانات: | BASE |
| DOI: | 10.1093/icb/icn031 |
|---|