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.
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