Epigenetics
Epigenetics is the study of heritable changes in gene expression and phenotype due to processes that are independent of the DNA sequence. Such changes (e.g. DNA methylation) can arise from external environmental factors. Embryonic development is a phase when an organism is particularly sensitive to external endocrine stimuli. It has been proposed that the exposure of the fetus to endocrine disrupting chemicals (EDCs) can have adverse effects on its health, some of which are only revealed in the adult organism.
We study the effects of estrogens at very low doses during pregnancy. This is of importance since external effects of a specific substance may perturb the endogenous hormonal balance during pregnancy. We use the pig as an animal model because it displays endocrine similarities to women during pregnancy, particularly placental production of estrogens.
Master thesis
The following master thesis is available:
Epigenetic effects of estrogen exposure on reproductive and somatic tissues in gilts.
Studies have indicated that endocrine disrupting chemicals (EDCs) might have adverse effects on the reproductive system of animals and humans, possibly leading to reduced fertility and increased rates of cancer. The aim of this master thesis is to study the effects of short-term exposure to the most potent natural estrogen, estradiol-7β (E2), in gilts. Gilts were exposed to different doses E2 during the preimplantation development of their embryos.
This will be done by molecular biological analysis of tissue samples collected in an animal trail in 2019. Specifically, the project will involve isolation of RNA and DNA, quantification of mRNA expression by qPCR and measurement of DNA methylation by pyrosequencing.
Master thesis
Quantification of estrogens and their metabolites in mammalian tissues using an LC-MS/MS based approach
Background
Estrogens belong to the category of sex steroid hormones. In mammals, they are crucial for the development and regulation of the female reproductive system. While the most potent endogenous estrogen is estradiol-17β (E2), the most abundant free estrogen within the body circulation is estrone (E1). Both are conjugated during the phase II metabolism resulting in estrogen sulfates and glucuronides, respectively. Estrogen conjugates lack the ability to bind the estrogen receptor (ER) and are therefore not functionally active. However, they are considered to serve as a circulating reservoir for free estrogens. Target tissues like the female endometrium express transporters and enzymes specific for estrogen conjugates, thereby regulating local estrogen action.
Estrogens taken up from the environment can act as endocrine disrupting chemicals (EDC). The most studied synthetic EDC compound exerting estrogen action is Bisphenol A. Endogenous estrogens (E2 and E1) can likewise act as EDCs, specifically at low doses.
We have exposed pregnant gilts as model species to E2 by orally applying different doses of E2. Post oral uptake, E2 is absorbed and subsequently metabolized during hepatic first-pass metabolism. The metabolites are then circulating via the blood stream and distributed to target tissues.
Aim
Recently, we have successfully established an ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) based method to quantify estrogen conjugates in plasma. The quantification of the estrogens is performed on a nanoAcquity UPLC system coupled to a triple-stage quadruple mass spectrometer following solid phase extraction to extract estrogens from plasma. The task of this MSc thesis is to expand the method to quantify free and conjugated estrogens in liver, endometrium, and fat tissue. Thereby, the property of EDC acting through their interim state as conjugated forms will be assessed.
Applied Techniques
Solid-phase extraction (SPE), ultra-performance liquid chromatography (UPLC), nano-electrospray ionization (Nano-ESI), Triple-Quadruple Mass Spectrometry (Triple-Quadruple MS)
Duration
6 months (minimum)
Starting Date
please contact us
How to apply
Please apply via email with the title of the project in the subject line and address it to Anna Hankele (). Please, provide an up-to-date CV, university transcripts and a cover letter.
Requirements and Conditions
Bachelor's degree in biochemistry, chemistry, biology, agronomy, or further relevant disciplines
Independence and capacity for teamwork
Experience or strong interest in laboratory work in the field of LC-MS/MS