The development of the vascular system is obviously central to the successful de
ID: 74009 • Letter: T
Question
The development of the vascular system is obviously central to the successful development of vertebrates. The development of the peripheral circulatory system appears to begin with a network of interconnected vessels. Following nerve growth into the region, some of the vessels align closely with the nerves. These vessels then differentiate into arteries; the nonaligned vessels become the veins. It was determined that a paracrine hormone isolated from sensory neurons, vascular endothelial growth factor A (VEGFA), could act in vitro to initiate arterial differentiation. This lead a group of researchers to propose that VEGFA was the molecule that organized the arterial network and caused its differentiation. The problem was verifying it in vivo. VEGFA null mice die during embryogenesis and never get far enough along to develop the circulatory system. They developed a line of mice expressing Cre recombinase, that could selectively shut off VEGFA in limb skin. They found that the initial capillary network aligned with the nerves much the same way as it did in normal mice, but vessels failed to differentiate into arteries. Do these data support their hypothesis? Why or why not.Explanation / Answer
Cre recombinase acts tissue specifically and time specific,Cre- Lox system is v.much specific,the enzyme after getting activated shut off VEGFA specifically in limb,
platelet-derived growth factor (PDGF)/vascular endothelial growth factor (VEGF) family =encodes a protein that is often found as a disulfide linked homodimer. acts on endothelial cells and has various effects, mediating increased vascular permeability, Inducing angiogenesis, vasculogenesis and endothelial cell growth, promoting cell migration, and inhibiting apoptosis.
effects on a number of other cell types stimulation monocyte/macrophage migration, neurons, kidney epithelial cells. In vitro, VEGF-A stimulate endothelial cell mitogenesis and cell migration.vasodilator and increases vascular permeability factor.DNA encoding the gene of interest is integrated into a vector along with elements that are able to promote the gene’s expression. The vector is then injected either into muscle cells of the heart or the blood vessels supplying the heart into the limb, then it can be seen that differentiation taking place in arteries