Masterarbeit, 2007
33 Seiten, Note: 1,0
Abstract
Chapter 1
Introduction
1.1 Zebrafish hematopoiesis
1.2 GATA-1 and Co-factors
1.2.1 The role of GATA-1
1.2.2 GATA-1 related factors
1.3 Epo and EpoR
1.4 Oxygen dependent development
1.5 Intention of this study
Chapter 2
Material and Methods
2.1 Animals
2.2 Imaging system
2.3 Epo mRNA
2.4 Statistics
Chapter 3
Results
3.1 General aspects
3.2 Total cell number
3.3 Manually counted fluorescent cells
3.4 GATA-1 expression
3.5 Epo expression
Chapter 4
Discussion
4.1 General aspects and observations
4.2 Pros and cons of DsRed
4.3 Epo and GATA-1
4.4 In vivo imaging
4.5 Conclusion
This study aims to establish a non-invasive digital imaging method for quantifying fluorescently marked protein expression in living zebrafish, while investigating how hypoxia influences GATA-1 and erythropoietin (Epo) expression levels during early larval development.
4.2 Pros and cons of DsRed
The protein drFP583 (DsRed) is a fluorescence protein which was found in Indo-pacific reef corals of the genus Discosoma [77]. DsRed has a few advantages and disadvantages compared to the already well known Green Fluorescent Protein (GFP) and its mutants. First, its excitation and emission maxima lies at 558 nm and 583 nm, respectively, which is at higher wavelength than the GFP mutants produced to date. Above 550 nm the interference from eventually existing endogenous fluorophores is less severe [78]. Second, DsRed shows a much higher pH insensitivity compared to GFP and it’s more resistant to photobleaching. Studies showed that it takes 1 h to bleach 90% when exposed to a beam of 1.2 W * cm−2 of 540 nm light [62]. In this experiment a 543 nm 5 mW HeNe laser was used and exposure time was in the range of seconds. Under this circumstances photobleaching in the current study should be irrelevant.
The major disadvantage of DsRed is its maturation kinetics. Baird et al showed that it takes at least 2 days at room temperature (20) to maturate and reach its full red fluorescence intensity [62]. To calculate the approximate time to reach full fluorescence at 28 the following formula (van’t Ho equation) was used:
Chapter 1: Provides a comprehensive biological background on zebrafish, hematopoietic processes, the function of GATA-1 and Epo, and the physiological responses to hypoxia.
Chapter 2: Describes the experimental setup, including the breeding of transgenic zebrafish, the hypoxic chamber specifications, and the methodologies for fluorescence imaging and mRNA quantification.
Chapter 3: Presents the observational results regarding total blood cell counts, fluorescent cell patterns, and expression levels of GATA-1 and Epo under different oxygen environments.
Chapter 4: Interprets the findings by comparing them with existing literature, discusses the limitations of the imaging technique, and concludes on the viability of the used methods for protein quantification.
Zebrafish, GATA-1, Erythropoietin, Epo, Hypoxia, Hematopoiesis, Digital imaging, Fluorescence, DsRed, Gene expression, Erythrocytes, Larval development, Stress response, Transcription factors, Protein quantification
This thesis investigates the relationship between GATA-1 and Erythropoietin (Epo) expression in zebrafish larvae and their responses to hypoxic environmental stress.
The primary aim is to validate a non-invasive, digital imaging method for quantifying fluorescence-marked proteins in living zebrafish embryos and larvae.
The study focuses on zebrafish hematopoiesis, the role of transcription factors like GATA-1, the Epo/EpoR signaling pathway, and developmental adaptations to low oxygen tension.
The study employs digital image analysis using laser scanning microscopy, mRNA quantification via real-time PCR, and statistical evaluation using the Mann-Whitney U-Test and Pearson’s correlation.
It details the materials and methods used for breeding and hypoxic treatment, presents data on blood cell concentration and protein expression over time, and discusses the physiological implications of these results.
The work is defined by terms such as zebrafish, GATA-1, Epo, hypoxia, fluorescence imaging, and hematopoiesis.
The model was chosen because the fluorescence protein DsRed allows for real-time visualization of gene expression in transparent animals, facilitating non-invasive study of red blood cell development.
Surprisingly, the study found that GATA-1 fluorescence levels were lower in the hypoxia-treated group than expected, potentially due to energy-saving mechanisms or the influence of glucocorticoids.
The author concludes that while the method is a powerful tool for relative protein quantification in living animals, results should ideally be verified by absolute quantification methods like RT-PCR.
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