Biology Reference
In-Depth Information
Chapter 2
Hagfish Slime Threads
Douglas Fudge
Department of Integrative Biology,
University of Guelph Guelph, Ontario, Canada
dfudge@uoguelph.ca
Hagfish slime threads form the fibrous fraction of the defensive slime
of hagfishes. The threads develop within specialized cells within
the slime glands and consist of a dense bundle of the cytoskeletal
elements known as intermediate filaments. The threads leave the
hagfish's body in a condensed state, but quickly unravel into fine
protein strands that are more than 10 cm long and approximately
2
µ
m in diameter. The proteins that make up the threads are
dominated by
-helical secondary structure, but when acted upon
by an external force, they stretch and adopt structures dominated by
β
α
-sheets. In this state, slime threads exhibit Congo red meta-
chromasia and birefringence. These stretch-transformed threads
differ from conventional amyloids in several ways. Most importantly,
strands within
β
-sheets run parallel to the fibre axis, unlike the cross-
β
arrangement in typical amyloid fibrils. This arrangement means that
stretched slime threads possess little in the way of “hidden length”
 
 
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