Interactions between paralytic shellfish poison (PSP) and
components of the butter clam (Saxidomus giganteus) were studied to
determine which component was involved in the binding and retention
of PSP by the butter clam, and to characterize the nature and
strength of the interaction. A simple and accurate assay for PSP
in buffer and salt solutions was developed for this study using the
Folin-Ciocalteau phenol reagent.
Equilibrium dialysis binding experiments with PSP and bovine
serum albumin or fibrinogen indicated that proteins did not interact
significantly with PSP. Binding experiments with PSP and a butter
clam siphon homogenate indicated an apparent electrostatic interaction
between PSP and some component of the clam siphon homogenate,
which was later identified as melanin. Synthetic and natural
clam melanin interacted strongly with PSP, and the interaction was similar in nature to a cation exchange reaction.
The interaction between PSP and melanin was rapid, reaching
an equilibrium within one hour at 25°C. The interaction was strongly
influenced by pH; maximum binding took place at pH 6.0 to 8.0, but at
pH 2.0 to 3.0 there was essentially no binding. The interaction was
reversible and rapid desorption of bound PSP took place at pH 3.0.
The interaction was also affected by the presence of competing
cations; tri-, di-, and monovalent cations, in that order of effectiveness,
interfered with the binding and caused desorption of bound
PSP.
The anatomical distribution of melanin in butter clams
paralleled the distribution of PSP, and PSP was apparently bound to
melanin in toxic butter clam siphons. Butter clams, which retain
PSP for longer periods than do other bivalve mollusks, had a higher
rnelanin content in the interior walls of their siphons than the other
mollusks studied.
The close relationship between the distribution of PSP and of
melanin in butter clams together with the observed electrostatic
interaction between PSP and melanin suggest that melanin may play
an important role in the retention of PSP in butter clams. The
reversible nature of the PSP-melanin interaction in the presence of
competing cations suggests that polyvalent salt solutions may be used
in the detoxification of toxic butter clams. / Graduation date: 1972
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/26878 |
| Date | 16 December 1971 |
| Creators | Price, Robert J. (Robert James), 1942- |
| Contributors | Lee, J. S. |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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