Cardiac development

Question 1

the zebra fish model advantages

Answer 1

Genetics, mutagenesis, transgenesis
Transparent embryos
Short generation time
Genome fully sequenced

Question 2

the zebra fish model disadvantages

Answer 2

Experimental manipulation (cell transplantation) difficult
Genome tetraploid

Question 3

the african claw frog advantages

Answer 3

Excellent for experimental manipulations
Early stages are accessible
Transgenesis is possible. Genome is currently sequenced.

Question 4

the African claw frog disadvantages

Answer 4

Genetics is not possible. Long generation time

Question 5

the chick embryo adv and disadv

Answer 5

Advantages:
Experimental manipulations are easily done.
Established model in Developmental Biology
Amniote embryo. Genome is fully sequenced.

Disadvantages:
No Genetics (but RNAi, Morpholinos, Viruses)

Question 6

what are amniotes? its model?

Answer 6

they have embryos developing outside and aquatic environment. the chick embryo is a model

Question 7

what is patterning?

Answer 7

Generation of positional information using a morphogen gradient

Question 8

Signalling molecules involved in embryonic development are :

Answer 8

the fibroblast growth factors, hedgehogs, wnts, TGFs and the Notch/Delta families.

Question 9

how do the signalling molecules act usually and how is this regulated?

Answer 9

act by forming concentration gradients (morphogens) inducing different cell reactions (target genes) after reaching threshold concentrations.
4. Important modulators of morphogen concentration are secreted antagonists,which help top shape concentration gradients for signalling molecules.

Question 10

what determines the developmental fate of the cells in the embryo?

Answer 10

the location where they end up

Question 11

which germ layer is the site for the development of the heart?

Answer 11

Cardiac muscle cells develop in the lateral plate mesoderm.

Question 12

Specification of cardiac mesoderm involves signals primarily from where?

Answer 12

from the underlying foregut endoderm

Question 13

what are the endodermal signals for heart?

Answer 13

• Endodermal signals include BMP2, FGF8, Shh and the Wnt antagonist crescent.

Question 14

how does the midline tissue prevent cardiac development in its vicinity?

Answer 14

The midline tissue secretes BMP antagonists and Wnt factors which prevent cardiac induction in its vicinity

Question 15

After chamber development, cells that form the primary heart tube contribute only to what?

Answer 15

After chamber development, cells that form the primary heart tube contribute only to the left ventricle.

Question 16

how does the heart grow?

Answer 16

Caudally and cranially additional mesoderm is added. Specification of cardiac mesoderm is an ongoing process at both poles. The heart thereby grows by adding cells at both poles of the tube.

Question 17

what does the second heart field produce?

Answer 17

This mesoderm (aka second heart field) forms the proximal and distal outflow tract and the right ventricle at the cranial end and the atria and sinus venosus at the caudal end.

Question 18

Primary and second heart fields differ in WHAT?

Answer 18

in their utilization of promoter elements and some transcription factors do produce a selective phenotype in the secondary heart field.

Question 19

is There correlation (co-linearity) between the A/P position of the precardiac cells in the primitive streak and their later position in the the tubular heart??

Answer 19

YES

Question 20

where are the medially and laterally positioned cells after fusion?

Answer 20

Cells that are medially positioned are dorsally-localized after fusion (forming the dorsal mesocardium) while lateral cells are forming part of the primary tubular heart

Question 21

what does the fusion of the two heart field depend on?

Answer 21

forming part of the primary tubular heart.

• Fusion of the two heart fields depends on foregut closure. Failure to fuse produces cardia bifida.

Question 22

how does the vertebrate heart loop? what is the position?

Answer 22

The vertebrate heart loops to the right. This morphogenetic movement positions the heart in the body (the heart is on the left side).
• Cardiac looping is part of the left-rigth asymmetry pathway.

Question 23

what is the next step after the looping?

Answer 23

The next step in the process is highly conserved and involves the induction of a leftsided expression domain of the signalling molecule nodal, which subsequently activates the transcription factor Pitx2 on the left side of the embryo

Question 24

what is the ultimate step in the heart looping?

Answer 24

The ultimate step involves the asymmetric morphogenesis of the heart

Question 25

same transcription factor is utilized multiple times during cardiac development. give an example

Answer 25

Nkx2.5 for example is important for cardiac recruitment, but also is required for cardiac septation and cardiac conduction tissue development.

Question 26

expression of what demarcates the cardiac conductive system?

Answer 26

The expression domain of Tbx3 demarcates the cardiac conduction tissue

Question 27

what substances play a role in Purkinje fiber induction?

Answer 27

Endothelin plays a role in inducing cardiac Purkinje fiber cell.
In mammals the signaling molecule neuregulin appears to promote purkinje fibre development.

Question 28

• The linear heart tube and the heart chambers differ in their gene expression programs. how does this become apparent?

Answer 28

This becomes apparent in the expression of the ANF gene, which is expressed in chamber myocardium but is absent from the tubular heart myocardium

Question 29

what type of cells are there initially in the heart tube?

Answer 29

• Initially at the tubular heart stage the entire myocardium has a node-like character. The primary pacemaker is localized in the most recently formed cardiac myocytes at the venous pole.

Question 30

when and what demarcates the nodular tissue?

Answer 30

Subsequently after chamber formation is initiated, the expression of Tbx2 and Tbx3 demarcates the nodular tissue. These cells are hindered to maturate into chamber myocardium and thereby retain the primitive characteristics of the tubular heart.

Question 31

PE (proepicardium) develops where?

Answer 31

The PE (proepicardium) develops on the venous pole of the heart and subsequently colonizes the heart to form the epicardium

Question 32

the epicardial derive cells (EPDCs) do what>

Answer 32

Epicardial derive cells (EPDCs) invade the heart and differentiate into the coronary vasculature and cardiac fibroblast

Question 33

what is the myocardium strongly dependent on?

Answer 33

• The myocardium is strongly dependent on interaction with the epicardium which promotes myocardial growth