Characterization of mucus-associated proteins from abalone (Haliotis) - candidates for chemical signaling
Kuanpradit, C and Stewart, MJ and York, PS and Degnan, BM and Sobhon, P and Hanna, PJ and Chavadej, J and Cummins, SF, Characterization of mucus-associated proteins from abalone (Haliotis) - candidates for chemical signaling, The FEBS Journal, 279, (3) pp. 437-450. ISSN 1742-464X (2012) [Refereed Article]
Living in groups is a widespread phenomenon in the animal kingdom. For
free-spawning aquatic animals, such as the abalone (Haliotis), being in the
close proximity to potential mating partners enhances reproductive success.
In this study, we investigated whether chemical cues could be present in
abalone mucus that enable species-specific aggregation. A comparative MS
analysis of mucus obtained from trailing or fixed stationary Haliotis
asinina, and from seawater surrounding aggregations, indicated that watersoluble
biomolecules are present and that these can stimulate sensory activity
in conspecifics. Purified extracts of trail mucus contain at least three
small proteins [termed H. asinina mucus-associated proteins (Has-MAPs)-
13], which readily diffuse into the surrounding seawater and evoke a
robust cephalic tentacle response in conspecifics. Mature Has-MAP-1 is
approximately 9.9 kDa in size, and has a glycine-rich N-terminal region.
Has-MAP-2 is approximately 6.2 kDa in size, and has similarities to schistosomin,
a protein that is known to play a role in mollusc reproduction.
The mature Has-MAP-3 is approximately 12.5 kDa in size, and could only
be identified within trail mucus of animals outside of the reproductive season.
All three Has-MAP genes are expressed at high levels within secretory
cells of the juvenile abalone posterior pedal gland, consistent with a role in
scent marking. We infer from these results that abalone mucus-associated
proteins are candidate chemical cues that could provide informational cues
to conspecifics living in close proximity and, given their apparent stability
and hydrophilicity, animals further afield.