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1.
J Exp Biol ; 221(Pt 24)2018 12 12.
Artigo em Inglês | MEDLINE | ID: mdl-30541919

RESUMO

Hagfishes defend themselves from fish predators by producing defensive slime consisting of mucous and thread components that interact synergistically with seawater to pose a suffocation risk to their attackers. Deployment of the slime occurs in a fraction of a second and involves hydration of mucous vesicles as well as unraveling of the coiled threads to their full length of ∼150 mm. Previous work showed that unraveling of coiled threads (or 'skeins') in Atlantic hagfish requires vigorous mixing with seawater as well as the presence of mucus, whereas skeins from Pacific hagfish tend to unravel spontaneously in seawater. Here, we explored the mechanisms that underlie these different unraveling modes, and focused on the molecules that make up the skein glue, a material that must be disrupted for unraveling to proceed. We found that Atlantic hagfish skeins are also held together with a protein glue, but compared with Pacific hagfish glue, it is less soluble in seawater. Using SDS-PAGE, we identified several soluble proteins and glycoproteins that are liberated from skeins under conditions that drive unraveling in vitro Peptides generated by mass spectrometry of five of these proteins and glycoproteins mapped strongly to 14 sequences assembled from Pacific hagfish slime gland transcriptomes, with all but one of these sequences possessing homologs in the Atlantic hagfish. Two of these sequences encode unusual acidic proteins that we propose are the structural glycoproteins that make up the skein glue. These sequences have no known homologs in other species and are likely to be unique to hagfishes. Although the ecological significance of the two modes of skein unraveling described here are unknown, they may reflect differences in predation pressure, with selection for faster skein unraveling in the Eptatretus lineage leading to the evolution of a glue that is more soluble.


Assuntos
Feiticeiras (Peixe)/fisiologia , Muco/química , Água do Mar/química , Animais , Feiticeiras (Peixe)/química , Solubilidade , Especificidade da Espécie
2.
Nat Commun ; 5: 3534, 2014 Apr 04.
Artigo em Inglês | MEDLINE | ID: mdl-24698953

RESUMO

The defensive slime of hagfishes contains thousands of intermediate filament protein threads that are manufactured within specialized gland thread cells. The material properties of these threads rival those of spider dragline silks, which makes them an ideal model for biomimetic efforts to produce sustainable protein materials, yet how the thread is produced and organized within the cell is not well understood. Here we show how changes in nuclear morphology, size and position can explain the three-dimensional pattern of thread coiling in gland thread cells, and how the ultrastructure of the thread changes as very young thread cells develop into large cells with fully mature coiled threads. Our model provides an explanation for the complex process of thread assembly and organization that has fascinated and perplexed biologists for over a century, and provides valuable insights for the quest to manufacture high-performance biomimetic protein materials.


Assuntos
Estruturas Animais/citologia , Proteínas de Peixes/ultraestrutura , Feiticeiras (Peixe)/metabolismo , Proteínas de Filamentos Intermediários/química , Estruturas Animais/metabolismo , Estruturas Animais/ultraestrutura , Animais , Proteínas de Peixes/metabolismo , Feiticeiras (Peixe)/citologia , Feiticeiras (Peixe)/ultraestrutura , Proteínas de Filamentos Intermediários/metabolismo , Proteínas de Filamentos Intermediários/ultraestrutura
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