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Primordial
hermaphroditic
gonad
Sox3, Aromatase
High E 2 level
Ovary
Sox3, p450 aromA,FTZ-F1
Dm rt1,sox9, TS H
High T level
T
E
S
T
I
S
Fig. 44. A hypothetic model of genetic and endocrine mechanisms of protogynous sex change
in hermaphroditic groupers. ← = inhibition, → = activation
like G. aculeatus sox9b, O. latipes sox9b and D. rerio sox 9b as well as
protogynous hermaphrodites E. coioides sox9 and M. albus sox9a1. The
cluster 2 includes D. rerio sox9a, G. aculeatus sox9a, O. latipes sox9a and
Monopterus albus sox9a (Luo et al., 2010). Clearly, both gonochoristic
and hermaphroditic fi shes employ the same sex differentiation genes.
sox9 is a sex related transcription factor and the earliest known marker
of Sertoli cell differentiation. Over-expression of sox9 causes male
sexual development in an XX individual (Gardner et al., 2003).
In E. coioides sox3 expression is detected very early in the nuclei of
some PGCs along germinal epithelium. Ecsox3- positive PGCs develop
toward spermatogonia. But on cessation of Ecsox3 expression, the
expressed Ecsox3 are concentrated in one or two signal spots and
are located outside the nuclei. Ecsox3 transcripts begin to express at
the lowest, as detected from MT-treated sex reversing grouper. The
interesting data of Yao et al. (2007) indicate that as the transcription
factor, Ecsox3 has a more important role in oogenesis than
spermatogenesis. sox5 is involved in expressing Ikappaβ, a protein
 
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