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Procedure

I. Animals:

Strongylocentrotus purpuratus, from the Pacific coast, Arbacia punctulata, from the Atlantic Coast or Lytechinus variegatus, from Florida can be used for this experiment. S. purpuratus gametes and embryos must be kept close to 12- 13ºC, or they will not develop.

Gamete collection by induced spawning

1. Induce spawing of gametes and fertilize as described in the basic protocols.

2. Collect both sperm and eggs.

II. Treatment with LiCl Solutions and Examination:

1. Use a 60 mM solution of LiCl in ASW to prepare 30 mM and 15 mM solutions.

2. At the two-cell stage, transfer embryos from ASW to seawater with each of the three LiCl concentrations. A quarter of the embryos should remain in ASW as a control group.

3. At the mesenchyme blastula stage, transfer 50 ml of embryos in finger bowl to ASW.

4. Observe samples of embryos from a control (ASW with no lithium added) culture and each of the experimental cultures the next day.

5. Use 2-3 drops eggs/embryos on a depression slide to compare developmental rate and morphology of the groups; focus on vegetal area morphology of embryos.

© Cebra-Thomas, 2004

Last Modified: 1 May 2004

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