Hagfish Slime Threads - The Functional Fold: Amyloid Structures in Nature - page 16

or “sacrificial bonds” and as such are quite stiff, without an obvious
yield point. The study of hagfish slime thread mechanics has led to
unexpected insights into the function of intermediate filaments in
other systems, including the cytoskeleton of live cells and

α

-keratins.
Although amyloid-like structures only appear in slime threads
outside of the animal's body, it is possible that exceptional mechanical
stresses could lead to amyloid-like structures within cells, with
potential consequences for the development of conformational
disease.

2.1 Introduction

Hagfishes are a group of ancient marine animals that pre-date the
evolution of fishes. Phylogenetically speaking, they belong to the
taxon Myxinoides, which is the sister taxon of Vertebrata. The 66 or so
extant species of hagfishes

1

are found in an anti-tropical distribution
and are typically found at depths greater than 100 m.

2

Hagfishes
spend most of their time near or on the seafloor, with some species
specializing in burrowing in soft sediments. Their lifestyle typically
involves opportunistic scavenging as well as predation on benthic
invertebrates like polychaete worms.

2

They have a low metabolic
rate that allows them to go for months without feeding, but they can
very quickly take advantage of carcasses that land on the bottom.
In studies of scavenging ecology in deep sea habitats, hagfishes
typically are one of the first species to arrive at baited traps.

3
Hagfishes are remarkable creatures in many ways, including an
ability to tie their body in an overhand knot to gain purchase on a
particularly tough food source.

4

But hagfishes are best known for
their superlative sliming abilities, which have earned them the
common name “slime eel”. Hagfishes have an astonishing ability to
produce large volumes of slime when they are perturbed or stressed,
and they do so far more quickly than the many marine species that
appear to simply increase epidermal mucous secretions in response
to stress. A typical mass of slime released from the Pacific hagfish
Eptatretus stoutii

has a volume of about a litre and can be formed in

5,6

less than 100 ms (Fig. 2.1).