Objective:
To
test the effects of UV radiation at 254nm on Sea Urchin
embryo development after radiation at the 2-cell
stage.
Background:
Sea
Urchins exhibit radial holoblastic cleavage. The first and
second cleavages are perpendicular to one another
and go
through the animal and vegetal poles. The subsequent
cleavages separate the cells into mesomeres,
macromeres,
and micromeres. Sea Urchins undergo formation of the
blastula and gastrulation before developing into
a
mature
embryo.
UV
light is harmful to many organisms just as it is harmful to
humans. Many eggs of marine animals including sea
urchins
have a high concentration of mycosporine amino acids that
protect them from UV damage. Mycosporine amino
acids
are obtained through the diet of the adult and are stored in
the egg. However, there is fear that the amphibians
are
declining
because of the increased UV-B reaching the earth's surface.
UV-A and UV-B reach the earth's surface. UV-B is
increasingly
hitting the earth's surface because of the depleting ozone
layer. One of the more common effects of UV-B is
adjacent
thymidines condensing into cyclobutane pyrimidine dimers
(CBPDs) which impede DNA replication and
transcription.
UV-C (200-280nm) is the most harmful type of UV to
organisms, however, due to oxygen in the
atmosphere
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