DORSAL VENTRAL PATTERNING IN DROSOPHILA ANIMATION скачать в хорошем качестве

DORSAL VENTRAL PATTERNING IN DROSOPHILA ANIMATION

#biologyanimation #DROSOPHILA #AXIS_FORMATION #DORSAL_VENTRAL_AXIS Generating the Dorsal-Ventral Axis (Dorsal-ventral patterning in the oocyte) • In this video we are going to learn about how dorsal-ventral patterning occurs in drosophila oocytes. • As oocyte volume increases, the Oocyte nucleus travels to the anterior dorsal side of the oocyte where it localizes gurken mRNA responsible for establishing the anterior-posterior axis. • This gurken mRNA also initiates the formation of the dorsal-ventral axis. • The gurken signal is received by the Torpedo proteins made by somatic follicle cells. • Due to the short diffusibility of the signal, only the follicle cells closest to the oocyte nucleus (i.e., the dorsal follicle cells) receive the Gurken signal, which causes the follicle cells to differentiate into a dorsal morphology and inhibit the synthesis of pipe protein. • This establishes the dorsal-ventral polarity in the follicle cell layer that surrounds the growing oocyte. • Hence, now the pipe protein is made only by the ventral follicle cells. • Maternal deficiencies of either gurken or torpedo gene cause ventralization of the embryo. • Pipe signal sulfates the ventral vitelline proteins and hence modifies the vitelline envelope. • Now, this sulfated vitelline membrane protein recruits Gastrulation defective (GD) which in turn cleaves Snake to its active form and forms a complex with Snake and then cleave Easter proteins into its active protease form. • Easter then cleaves the Spätzle protein and activated Spätzle binds to Toll receptor protein. • This Toll protein is a maternal product that is evenly distributed throughout the cell membrane of the egg but gets activated only after binding with Spätzle protein. • Toll activation activates Tube protein and a protein kinase called Pelle, which phosphorylate the Cactus protein bound to dorsal protein. • After phosphorylation, Cactus is degraded, releasing it from Dorsal. • Now this dorsal protein get free and enters the nucleus and thereafter ventralizes the cell by activating those genes responsible for specifying ventral cell types. • Hence, the dorsal protein is responsible for distinguishing the dorsum from ventrum in the fly embryo. • The Dorsal protein signals the first morphogenetic event of Drosophila gastrulation. • In the 16 ventral most cells of the embryo—those cells containing the highest amount of Dorsal in their nuclei—invaginate into the body and form the mesoderm and those cells present at more lateral become neurogenic ectoderm.