Aromatase as an enzyme and its role in the conversion of Androgens to female sex steroidal hormones, Aromatase sensitivity to temperature in animals with Temperature dependent sex determination (TSD)

1. Role of Aromatase in
sex determination
Abhijeet Bhattacharya
KSD’s Model College
Dombivali

2. Introduction
➢Sex determination is a mechanism which
determines the individual to be male or
female based on the sex chromosomes
present in it.
➢ In temperature-dependent sex
determination (TSD), the ambient
temperature of the embryos leads to the
development of the bipotential gonads
into either testes or ovaries.

3. Bipotential
Gonads
➢Gonadal development can be modified
by the concentration of sex steroid
hormones in the surrounding system of
the embryos.
➢ An excess of either testosterone or
estrogen during gonadal differentiation
leads to testicular or ovarian
development, respectively, regardless of
the surrounding temperature.

4. Aromatase
➢Cytochrome P450 aromatase, also
known as cyp19a1 or aromatase, is the
enzyme that irreversibly catalyzes
androgens into estrogens.
➢It is also called estrogen synthetase or
estrogen synthase.
➢The enzyme aromatase is found in many
tissues including gonads.
➢Conversion of androgens to estrogen is
done by aromatization.

5. Androgen to Estradiol conversion

6. Temperature-
dependent
sex
determination
➢Animals with Temperature-dependent sex
determination (TSD) more Aromatase
develops female offspring.
➢Aromatase activity is temperature sensitive.
➢However, high Aromatase concentration
overpowers the effect of temperature.
➢i.e. At male producing temperature, high
concentration of Aromatase will produce
female off springs and vice versa.

7. Effect on
Genetic sex
determination
➢Animals with genetic sex determination,
temperature does not affect aromatase
expression and function, suggesting that
aromatase is the target molecule for
temperature during TSD