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First published online December 2, 2005
Journal of Experimental Biology 208, 4613-4625 (2005)
Published by The Company of Biologists 2005
doi: 10.1242/jeb.01963

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Composition, morphology and mechanics of hagfish slime

Douglas S. Fudge^*, Nimrod Levy, Scott Chiu and John M. Gosline

Department of Zoology, University of British Columbia, 6270 University Boulevard, Vancouver, BC V6T 1Z4, Canada

View larger version (84K): [in a new window]   Fig. 1. Slime production by a hagfish in seawater. Photo courtesy of Chris Ortlepp.

View larger version (117K): [in a new window]   Fig. 2. Hagfish slime is formed from a concentrated exudate released by the slime glands. The exudate contains both coiled slime threads, or `skeins' (arrow) and mucin vesicles (arrowheads) that rupture in seawater. Scale bar, 50 µm.

View larger version (49K): [in a new window]   Fig. 3. Result of a typical `slimatocrit' trial, in which slime exudate was stained with Toluidine Blue and spun in hematocrit tubes to measure the volume fractions of thread cells and mucin vesicles. Mucin vesicles (dark staining) and gland thread cell skeins (GTCs) make up about equal amounts of the exudate.

View larger version (110K): [in a new window]   Fig. 4 Apparatus used for whole slime mechanical measurements. Fresh slime exudate was added to the top of a 2 l beaker and slime was formed by the gentle stirring caused by oscillations of the plunger. Hydration of slime exudate led to unraveling of gland thread cell skeins and their subsequent elongation and attachment to the inside of the beaker and the plunger. Force on the plunger was measured using a 100 g load cell.

View larger version (10K): [in a new window]   Fig. 5. Scaling of stored slime mass with body mass. The slope of the line suggests that stored slime represents 3–4% of the hagfish's mass.

View larger version (26K): [in a new window]   Fig. 6. (A) The diameter of the thread on the outside of intact slime thread skeins as a function of position along their longitudinal axis. Note the bi-directional taper. (B) A composite of four SEM images along a single thread cell that demonstrates how thread diameter tapers off at both ends of the cell (GTC).

View larger version (16K): [in a new window]   Fig. 7. Viscosity of mucin solutions prepared in distilled water (blue circles) and seawater (purple squares) as function of concentration. Note that the viscosity in seawater was low even at the highest mucin concentrations tested.

View larger version (27K): [in a new window]   Fig. 8. Representative force traces showing slime development over time in (A) seawater, (B) distilled water (dH2O), (C) seawater containing 5 mmol l–1 DTT (DTT). Arrows denote when the slime exudate was added to the beaker of seawater.

View larger version (11K): [in a new window]   Fig. 9. Representative force traces for single plunger oscillations in (A) seawater, (B) distilled water (dH2O) and (C) seawater containing 5 mmol l–1 DTT.

View larger version (19K): [in a new window]   Fig. 10. Representative curves of stress–relaxation of whole hagfish slime in the same apparatus as described in Fig. 7. The slime was strained by a 50 mm movement of the plunger within the slime and held for 500 s. Stress relaxation in seawater (SW) and distilled water (dH2O) was more rapid at first and then settled into a slower rate of force decay. In seawater containing 5 mmol l–1 DTT, this initial rapid force decline was absent.

View larger version (13K): [in a new window]   Fig. 11. Lifting about 1 l of slime into air using a 4 mm mesh lined cylinder resulted in massive water loss from the slime. (A) Water left in the beaker as a function of time measured as load on the force transducer. (B) Rate of water egress from the slime calculated from the same data. These results demonstrate that the slime is not able to organize water over long time scales.

View larger version (101K): [in a new window]   Fig. 12. Congo Red (CR) staining of hagfish slime. Slime threads (but not mucins) bound CR, but only threads from slime that was physically perturbed showed metachromasia. (A) Bright field image of slime threads from unperturbed slime. (B) Dark-field (polarisers crossed) image of same threads. Note the lack of CR metachromasia in most of the threads. (C) Bright field image of threads from perturbed slime. (D) Same as C, dark field. (E) Bright field image showing bundling of slime threads in perturbed slime. (F) Same as E, dark field. Bar, 10 µm.

View larger version (16K): [in a new window]   Fig. 13. The ratio of mucin vesicles to thread surface area suggests that the threads are capable of binding every mucin vesicle. Here we depict an elongated slime thread with bound mucin vesicles before and after swelling (by a factor of three in all dimensions).