The transcription factor GATA-1 is essential for the development of the erythroid cell lineage in vertebrates. In this article we introduce a method to easily determine the approximately development status of red blood cells and the progression of blood formation by intensity of fluorescence in GATA-1/Ds-Red marked zebrafish. We classified the blood cells on the basis of their fluorescence intensity in 5 intensity stages (IS) with the brightest in IS 1. The comparison with our erythropoietin (Epo) data showed a noticable correlation between GATA-1, Epo mRNA and EPO protein level. Between 2 and 3 dpf we observed a major increase in blood cell concentration to circa 1200 cells*nl-1, until 15 dpf this value decreased to about the half. The appearance of IS 1 cells correspond approximately to the peaks in Epo cRNA copies and the highest values in EPO protein emerged about 1 day later. Our data show that the blood cell concentration, Epo and Gata-1 expression in zebrafish larvae is subjected to large fluctuations in the first few days of development.
Table of Contents
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
Research Objectives and Focus Areas
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.
- Development of a fluorescence-based cell quantification method in GATA-1/DsRed transgenic zebrafish.
- Analysis of red blood cell concentration dynamics under normoxic and hypoxic conditions.
- Investigation of the regulatory relationship between GATA-1 expression and Epo mRNA levels.
- Evaluation of hypoxia as an environmental stressor on early hematopoietic development and gene expression.
Excerpt from the Book
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:
Summary of Chapters
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.
Keywords
Zebrafish, GATA-1, Erythropoietin, Epo, Hypoxia, Hematopoiesis, Digital imaging, Fluorescence, DsRed, Gene expression, Erythrocytes, Larval development, Stress response, Transcription factors, Protein quantification
Frequently Asked Questions
What is the core focus of this master's thesis?
This thesis investigates the relationship between GATA-1 and Erythropoietin (Epo) expression in zebrafish larvae and their responses to hypoxic environmental stress.
What primary goal does the research aim to achieve?
The primary aim is to validate a non-invasive, digital imaging method for quantifying fluorescence-marked proteins in living zebrafish embryos and larvae.
What are the key thematic pillars of the study?
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.
Which scientific methods are utilized in the analysis?
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.
What does the main body of the work cover?
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.
How is the work characterized in terms of keywords?
The work is defined by terms such as zebrafish, GATA-1, Epo, hypoxia, fluorescence imaging, and hematopoiesis.
Why was the GATA-1/DsRed transgenic zebrafish model chosen for this study?
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.
How did hypoxia affect the GATA-1 expression levels compared to the control group?
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.
What were the main conclusions drawn regarding the used imaging methodology?
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.
- Quote paper
- Mag. Markus Holotta (Author), 2007, The influence of hypoxia on GATA-1 and Epo expression levels in developing zebrafish, Munich, GRIN Verlag, https://www.grin.com/document/85354
