Biology Reference
In-Depth Information
9
water.
Contributions of the thread and mucin vesicle components
are synergistic—neither alone can produce anything resembling
the native slime.
10
Further, the addition of the disulphide bond
reducer dithiothreitol to sea water delays the formation of the
slime and interferes with slime cohesiveness when slime exudate is
added.
5,10
This effect is most likely brought about by a disruption
of the disulphide bonds that hold mucin molecules into a coherent
network, although the details of this mechanism are still currently
unknown.
The mechanical properties of the slime are highly time- and
deformation-dependent, and in this way hagfish slime may best
be understood as an event rather than a conventional material. At
first glance, an average mass of slime secreted by a Pacific hagfish
appears to have a volume of about a litre, but this value depends
greatly on the speed and manner in which the slime is collected. If
the slime is quickly lifted out of water (Fig. 2.1), it brings with it a
great deal of this water, but if the slime is held in air, the majority of
water will eventually run free.
5
The dramatic egress of water from
the slime suggests that the large volume of slime produced is mostly
bulk sea water that is entrained in minute spaces within the slime.
This conclusion is further supported by a simple model of slime
morphology that demonstrates that it is not physically possible
for the mucin and thread components to immbolise a litre of sea
water.
5
Figure 2.3
Experiments with isolated fish heads demonstrate that
hagfish slime is effective at clogging gills. 6 Photo by Jeanette
Lim. See also Colour Insert.
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