VL8- Zebrafish and Morphogenesis Flashcards
Zebrafish (Danio rerio)
- first description in 1822
- Natural habitat: streams and rivers Himalya region (arose in Ganges region)
- resistanace to temperature -, pH levels- oxygen fluctation)
Why Zebrafish?
Danio rerio
- Excellent genetics
- short generation period
- large egg clutches
- extrauterine and transperent development
- rapid move of development
- early development is possible without functioning organs
- ease to perfome experimet embryponical manipulations
- chaep maintenance costs
-Circulatin water (24°-29°C)
-ca. 5 adults per Liter
-Matings are possible 1x/Week (100-500 eggs)
The Life ycle of Zebrafish
Danio rerio
- zebrafish embryos are generally transparent, their transparency can vary with developmental stage, and as they mature, pigmentation may affect their transparency.
- Mutant: a crystal clear zebrafish
90 Days from fertilization to fertile adult
Mutagenesis in Ethylnitrosourea - mapping stategies for mutantions
- Ethyl Nitrosourea (ENU) usually used in mice to reach a high effeicienr induction of point mutantions, randolmy diturbed through the germlin = highly potent mutagen.
- The chemical is an alkylating agent, and acts by transferring the ethyl group usually to thymine in nucleic acids
Determination, Fate & Specification
- Fate indicates what a cell will normally develop into if not challenged with another environment (based on its position within the embryo)
- Determination refers to a stable internal state of a cell that will not change even when transplanted into another environment
- A cell is specified when it develops into a particular fate even when kept in
isolation
The Zebrafish Fate Map
Ectoderm: Epidermis, Spinalcord, Forebrain, Midbrain, Hindbrain
Mesoderm: Somites, Heart, Notochord
Endoderm + Mesoderm: Blood, Pronephores, Prechordal plate
Genome of Zebrafish (Danio rerio)
- Genome size (Haploid state): 1,412 Gb disturbed among 25 chromosomes
- published online by sanger institute
- About 71% of the 20,479 protein-coding genes of Homo sapiens have
orthologs in the zebrafish genome. - In turn, 69% of the 26,206 protein-coding zebrafish genes have human counterparts.
- The increased gene number in the zebrafish genome originated from a whole-genome duplication during teleost evolution that was followed by a loss of many orthologs
Epithelial to mesenchymal transition
Background info
During embryogenesis epithelial layers frequently change into loosely organized
mesenchyme. This involves the opening of adherens junctions between epithelial
cells, detachment of cells from their basement membrane, their cellular conversion into individual or weakly adherening mesenchymal cells.
e.g: endothelial-to-mesenchymal transition (endMT): angiogenesis, cardiac cushion formation
Reverse process is mesenchymal-to-epithelial transition (MET), e.g. somitogenesis
What is special about the zebrafish herat, and how does it assembly?
- Survival of the early zebrafish embryo does not require a functional heart
- Muscular heart with 2 heart chambers (1 Atrium, 1 Ventricle)
- heart is able to regenerate
Nodal Pathway
Role: specifying the left-right axis and contributes to the patterning of the heart tube.
Type: Morphogen
Function: Guides cell fate and provides positional information during embryonic development by forming concentration gradient
BMP(Bone morphogenic protein)
Role: Involved in heart development and tissue patterning
Type: Morphogene
Function: Forms concentration gradients to influence cell differentiation and contribute to tissue organization.
–> They regulate cell fate, provide positional information, and contribute to the intricate processes of embryonic development.
Pattern formation by morphogene signaling
Background
The French Flag model:
* Cells can acquire an identity based on
positional information.
* One mechanism by which this is achieved involves morphogens.
* Morphogens diffuse over several cell diameters and induce different cell fates at different threshold concentrations
