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Morphogen Concentration

Submitted by rhallice on Sun, 11/05/2017 - 14:38

 

            Morphogens are chemical agents that are typically produced by source cells and diffuse across the surrounding tissues of an embryo setting up a concentration gradient. This concentration gradient of a biomedical molecule determines the fate of embryo development and also supply the positional information to cells in an embryo.  Drosophila also known as fruit flies make for the perfect model organism for studying embryonic development and genetics due to their numbers and ease of access. In a recent study scientist found that dorsal, a maternal effect gene, encodes for a morphogen gradient that regulates the development of ventral embryo structures. Drosophila embryos are separated into two major and important axes patterning: the anterior-posterior axis and the dorsal-ventral axis. The dorsal-ventral patterning axis determines the back (dorsal) and front (ventral) side of the embryo and is dependent on the ventral nuclear concentration of dorsal. The dorsal side of the embryo is developed when oocyte nucleus moves from posterior to anterior side of the embryo and expresses a protein called Gurken. When Gurken is present it repress the production of Pipe protein. The pipe protein is important in the pathway to get dorsal a morphogen into ventral nuclei and therefore to determine ventral identity. However once expressed Pipe begins the extracellular cascade to turn on Toll receptors on ventral embryo cells. This cascade continues intracellularly to separate the dorsal morphogen from Cactus. Once separated form Cactus, dorsal is able to move into the nucleolus of the ventral cell to act as a morphogen. Once inside the nucleus, the dorsal activates different genes depending on its concentration setting up a gradient turning on transcription factors twist and zen which in turn results in the formation of the embryonic mesoderm. The mesoderm (middle layer) is one of the three germ layers that are developed in an early embryo and arise to form muscle tissues and red blood cells.

 

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