Temperature regulates SOX9 expression in cultured gonads of Lepidochelys olivacea, a species with temperature sex determination.
Although sex determination starts in the gonads, this may not be the case for species with temperature sex determination (TSD). Since temperature affects the whole embryo, extragonadal thermosensitive cells may produce factors that induce gonadal sex determination as a secondary event. To establish if gonads of a species with TSD respond directly to temperature, pairs of gonads were cultured, one at female-promoting temperature (FPT) and the contralateral at male-promoting temperature (MPT). Histological and immunohistochemical detection of SOX9 revealed that the response to temperature of isolated gonads was similar to that of the gonads of whole embryos. While gonads cultured at MPT maintained SOX9 expression, it was downregulated in gonads at FPT. Downregulation of SOX9 took longer in gonads cultured at stage 23 than in gonads cultured at stage 24, suggesting that a developmental clock was already established at the onset of culture. To find out if sex commitment occurs in vitro, gonads were switched from FPT to MPT at different days. Results showed that the ovarian pathway was established after 4 days of culture. The present demonstration that gonads have an autonomous temperature detector that regulates SOX9 expression provides a useful starting point from which the molecular pathways underlying TSD can be elucidated.
Moreno-Mendoza
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N
Instituto de Investigaciones Biomedicas, Mexico, D.F, 04510, Mexico.
Harley
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VR
Merchant-Larios
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H
D000595:Amino Acid Sequence; D000818:Animals; D000939:Epitopes / Q000737:chemistry; D005260:Female; D018507:Gene Expression Regulation, Developmental / Q000502:physiology*; D006609:High Mobility Group Proteins / Q000032:analysis / Q000235:genetics*; D007150:Immunohistochemistry; D008297:Male; D008969:Molecular Sequence Data; D009924:Organ Culture Techniques; D010053:Ovary / Q000196:embryology*; D055758:SOX9 Transcription Factor; D012733:Sex Differentiation; D013696:Temperature; D013737:Testis / Q000196:embryology*; D014157:Transcription Factors / Q000032:analysis / Q000235:genetics*; D014426:Turtles / Q000196:embryology*
D000939:Epitopes; D006609:High Mobility Group Proteins; D055758:SOX9 Transcription Factor; D014157:Transcription Factors