Proteins encoded by early region (E1, E2, E3, E4) genes are involved in viral DNA replication, cell cycle modulation and defense system. The late region genes (L1, L2, L3, L4, L5) encodes the viral structural proteins.

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#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.

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#Unit 5. Developmental Biology

Two major mechanisms during fertilization in sea urchin:

Species-specific sperm attraction 

Species-specific sperm activation

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#Unit 5. Developmental Biology

Chemotaxis 

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

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#Unit 5. Developmental Biology

In Sea urchin,

Sperm-activating peptides provide direction to sperm during chemotaxis.

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#Unit 5. Developmental Biology

SAP in the egg jelly of the sea urchin Arbacia punctulata 

Resact (14-amino acid chemotactic peptide)

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#Unit 5. Developmental Biology

SAP in the egg jelly of, Strongylocentrotus purpuratus

Speract