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Fig. 7. Id2 transcription is upregulated in Ovol1-deficient germ cells and
is repressed by Ovol1 protein in vitro. (A) Increased levels of Id2 mRNA in
P16 Ovol1-/- testis. (B) In situ hybridization of P16
wild-type (A',C') and Ovol1-/-
(B',D') testis using an Id2 cRNA probe. (C' and D')
High magnification images of individual tubules showing the strongest Id2
expression. Arrowheads and arrows indicate the Id2-expressing primary
spermatocytes and the non-expressing spermatogonia, respectively. (C) Temporal
expression of Id2 during normal prepubertal testis development. (D) Repression
of Id2 promoter (Id2-P)-luciferase reporter expression by Ovol1. (E)
Activation of Id2-P-luciferase expression by VP16-Ovol1. The triangles
indicate increasing concentrations of expression vectors. The VP16 alone
control is at a concentration corresponding to the highest one used for
VP16-Ovol1. (F) Repression or activation is partially dependent on the CCGTTA
sequence in Id2 promoter. Each bar represents the average of triplicate
samples in a single experiment, and results are representative of several
independent experiments. Luciferase activities are normalized for transfection
efficiency by using a ß-actin promoter driving lacZ as an
internal control.