== Overview ==
Our general aim is to establish a simple synthetic organisim which will
be capable to measure the influence of endocrine disruptors on the
natural balance of sexual determination in all kind of vertebrates. The
measurement itself will be cost-efficient, environment-friendly and
sensitive.
Naturally occuring iron receptors of the PAQR family are found to
repress the fet3 promotor on high level of extra-cellular iron.
According to Smith et al. human mPR expressed in yeast induced the same
signal when binding to progesterone. Relying on this results we will
express various mPRs of Danio rerio and Xenopus laevis in yeast to
measure endocrine substances that influence fish and amphibians.
We will transform the negative signal (fet3 repression) into a positive
signal by regulating a repressor (rox1 or mig1) with Pfet3. This
repressor will in turn regulate the expression of the reporter gene
(firefly luciferase or beta-galactosidase) and allow quantitative
measurement.
Motivation
''Why do we want to establish a mechanism for steroid measurement?''
Steroid hormones, especially estrogens, occur in all vertebrates and
play a crucial role in sexual differentiation. In recent times the
pollution of waters with these hormones has become an increasing problem
for the aquatic fauna.
Particularly waters functionalized by humans or adjacent to human
settlements, e.g. in areas with agricultural use, show increased
concentrations of estrogen.
Scientific studies based on ''Danio rerio'' showed that the consequences
are devastating.
High concentrations of 17α-ethinylestradiol, a hormone in most
birth-control pills, affected the sex differentiation of ''Danio rerio''
leading to development of ovotestis or complete feminization (Andersenc,
2002).
Intersex-fish have been reported in UK rivers since 1978 downstream of
an sewage treatment plant.
We believe that a first step in finding a solution to this environmental
problem is an accurate and reliable method to quantify steroid
concentrations.
"
