Bicoid mRNA binds to dynein, a “minus-directed” motor protein associated with the nongrowing end of microtubules; dynein moves the bicoid mRNA to the anterior end of the egg. 

TLS Online TPP Program

#Id: 7023

#Unit 5. Developmental Biology

The daughter cell attached to the hub is maintained as a stem cell, whereas the cell that is not touching the hub becomes a gonialblast, a committed progenitor cell that will divide to become the precursors of the sperm cells.

TLS Online TPP Program

#Id: 7024

#Unit 5. Developmental Biology

The somatic cells of the hub create asymmetric proliferation by secreting the paracrine factor Unpaired onto the cells attached to them

TLS Online TPP Program

#Id: 7025

#Unit 5. Developmental Biology

Unpaired protein activates the JAK-STAT pathway in the adjacent germ stem cells to specify their self-renewal

TLS Online TPP Program

#Id: 941

#Unit 5. Developmental Biology

 The mode of fertilization in sea urchin being external, the egg and spermatozoa are released into the sea water.

TLS Online TPP Program

#Id: 942

#Unit 5. Developmental Biology

Two major mechanisms during fertilization in sea urchin:

Species-specific sperm attraction 

Species-specific sperm activation

TLS Online TPP Program

#Id: 943

#Unit 5. Developmental Biology

Chemotaxis 

sperms are attracted toward eggs of their species by following a gradient of a chemical secreted by the egg.