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Identification and Characterization of the Egg-Laying Hormone from the Neurosecretory Bag Cells of Aplysia


Toevs, Lois Schloemer (1970) Identification and Characterization of the Egg-Laying Hormone from the Neurosecretory Bag Cells of Aplysia. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/70RQ-P642.


This investigation has resulted in the chemical identification and isolation of the egg-laying hormone from Aplysia californica, Aplysia vaccaria, and Aplysia dactylomela. The hormone, which was originally identified as the Bag Cell-Specific protein (BCS protein) on polyacrylamide gels, is a polypeptide of molecular weight ≈ 6000, which is localized in the neurosecretory bag cells of the parietovisceral ganglion and the surrounding connective tissue sheath which contains the bag cell axons. All three species produce a hormone of similar molecular weight, but varying electrophoretic mobility as determined on polyacrylamide gels. As tested, the hormone is completely cross-reactive among the three species.

Although the bag cells of sexually immature animals contain the active hormone, sexual maturation of the animal results in a 10-fold increase in the BCS protein content of these neurons.

A seasonal variation in the BCS protein content was also observed, with 150 times more hormone contained in the bag cells of Aplysia californica in August than in January. This correlates well with the variation in the animals' ability to lay eggs throughout the year (Strumwasser et al., 1969). There are some indications that the receptivity of the animal to the available hormone also fluctuates during the year, being lower in winter than in swmner. The seasonal rhythm of the other species, Aplysia vaccaria and Aplysia dactylomela, has not been investigated.

A polyacrylamide gel electrophoresis analysis of water-soluble proteins in Aplysia californica revealed several other nerve-specific proteins. One of these is also located in the bag cell somas and stains turquoise with Amido Schwarz. The function of this protein has not been investigated.

Item Type:Thesis (Dissertation (Ph.D.))
Subject Keywords:(Neurophysiology and Developmental Biology)
Degree Grantor:California Institute of Technology
Major Option:Biology
Thesis Availability:Public (worldwide access)
Research Advisor(s):
  • Strumwasser, Felix
Thesis Committee:
  • Unknown, Unknown
Defense Date:9 December 1969
Funding AgencyGrant Number
Public Health ServiceUNSPECIFIED
Record Number:CaltechTHESIS:08282015-154034894
Persistent URL:
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:9123
Deposited By: Benjamin Perez
Deposited On:28 Aug 2015 22:55
Last Modified:23 Jul 2021 22:38

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