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Profiles
of genes expressed in various organs of Japanese chiton, Acanthopleura
japonica
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Hamaguchi
Masami and
Sasaki
Miho |
Chitons
have a various hard tissues and these morphological features are
use for identification of chitons. We are interested in the
mechanism of various hard tissues formation in the chiton. In
particular, the Japanese chiton, Acanthopleura japonica
has large amount of magnetite in the tooth cusp of the major
lateral teeth. In addition, ladula contains chitin and
hydroxyapatite and we try to clarify the mechanism of ladula
formation, now. The chiton radula is surrounded with a
monolayered sheet, radula sac, except for the anterior end of
the radula. It is proposed that the processed of
biomineralization is controlled by various organic materials.
For example, some enzymes and proteins regulate the transport of
ions, the reception and delivery of electrons. Also,
crystallization is initialized in the organic framework secreted
from the neighboring cells. Therefore in chiton redula, chitin
and the organic matrix produced in the radula sac covering the
radula teeth affect the mineralization of magnetite.
In hirtosa, aspartic acid, glutamic acid and glycine were
detected from an organic matrix of major lateral teeth(Evans et
al. 1991). Okoshi
et al. (1999) described how iron in
the chiton was supplied from food, microalgae etc, and
circulated through the body in the form of ferritin. We are
interested in the mechanism by which iron is converted
ferritin-form to magnetite in radula sac.
We
constructed cDNA libraries from the radula sac, HP and gonad
mRNAs and using suppressive subtraction, prepared specific genes
which control the deposition of minerals, chitin and
hydroxyapatite. We studied the relation between these genes and
biomineralization in the radula sac, particulary magnetite
formation. We will report informationof the genes expressed in
the chiton and discuss the correlation among the
genes and radula formation in chiton. |
