Mechanisms of Adhesion in Adult Barnacles

Power, Anne; Klepal, Waltraud; Zheden, Vanessa; Jonker, Jaimie; McEvilly, Paul; Byern, Janek von

doi:10.1007/978-3-7091-0286-2_9

Cited by 35 publications

(48 citation statements)

References 55 publications

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“…As barnacles grow during molting cycles, adhesive originating in unicellular cement glands is transported through a radial canal system of ducts to the periphery of the baseplate. 129,130 The low-viscosity adhesive is initially clear but solidifies and becomes insoluble within 6 h. 131 Whether or not the adult adhesive proteins are synthesized in distinct cell types, how and when they are mixed to form the glue, and the trigger to initiate solidification of the liquid glue are unknown.…”

Section: Glue Solidification: Cohesionmentioning

confidence: 99%

Natural underwater adhesives

Stewart

Ransom

Hlady

2011

J Polym Sci B Polym Phys

292

298

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The general topic of this review is protein-based underwater adhesives produced by aquatic organisms. The focus is on mechanisms of interfacial adhesion to native surfaces and controlled underwater solidification of natural water-borne adhesives. Four genera that exemplify the broad range of function, general mechanistic features, and unique adaptations are discussed in detail: blue mussels, acorn barnacles, sandcastle worms, and freshwater caddisfly larva. Aquatic surfaces in nature are charged and in equilibrium with their environment, populated by an electrical double layer of ions as well as adsorbed natural polyelectrolytes and microbial biofilms. Surface adsorption of underwater bioadhesives likely occurs by exchange of surface bound ligands by amino acid sidechains, driven primarily by relative affinities and effective concentrations of polymeric functional groups. Most aquatic organisms exploit modified amino acid sidechains, in particular phosphorylated serines and hydroxylated tyrosines (dopa), with high-surface affinity that form coordinative surface complexes. After delivery to the surfaces as a fluid, permanent natural adhesives solidify to bear sustained loads. Mussel plaques are assembled in a manner superficially reminiscent of in vitro layer-by-layer strategies, with sequentially delivered layers associated through Fe(dopa)3 coordination bonds. The adhesives of sandcastle worms, caddisfly larva, and barnacles may be delivered in a form somewhat similar to in vitro complex coacervation. Marine adhesives are secreted, or excreted, into seawater that has a significantly higher pH and ionic strength than the internal environment. Empirical evidence suggests these environment triggers could provide minimalistic, fail-safe timing mechanisms to prevent premature solidification (insolubilization) of the glue within the secretory system, yet allow rapid solidification after secretion. Underwater bioadhesives are further strengthened by secondary covalent curing.

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Section: Glue Solidification: Cohesionmentioning

confidence: 99%

Natural underwater adhesives

Stewart

Ransom

Hlady

2011

J Polym Sci B Polym Phys

292

298

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“…Despite inspiring scientific inquiry for more than a century3 and impeding maritime operations even today4, the permanent bond of adult barnacles is among the least understood. In contrast to marine organisms that use glues to fabricate protective shelters (e.g., sand-castle worm tubes5, case-maker fly larva retreats2, and amphipod tubes67) or tie themselves to rocks, (e.g., mussel byssus threads89) adult barnacles produce their adhesive interface in a sequential process hidden under their base as a part of their normal growth cycle1011. The recent finding that barnacle adhesive is nanostructured and held together as an amyloid-like material121314 further distinguishes it from archetypal marine adhesives processed into solid foams1915 or spun threads26.…”

mentioning

confidence: 99%

“…An observed release of proteins from bulk glue in the presence of reducing agents led to the assertion that disulfide bonding plays a role in cement cross-linking192328. However, there is no spectroscopic evidence for S-S bonding in the cement layer2930 and cysteine content remains low or nonexistent in the proteins thought to comprise bulk glue or the native cement itself1019. Discrepancies exist between the handful of identified components and the amino acid composition of the proteinaceous cement layer, while major components remain unsequenced.…”

mentioning

confidence: 99%

Sequence basis of Barnacle Cement Nanostructure is Defined by Proteins with Silk Homology

Fears

Leary

et al. 2016

Sci Rep

194

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Barnacles adhere by producing a mixture of cement proteins (CPs) that organize into a permanently bonded layer displayed as nanoscale fibers. These cement proteins share no homology with any other marine adhesives, and a common sequence-basis that defines how nanostructures function as adhesives remains undiscovered. Here we demonstrate that a significant unidentified portion of acorn barnacle cement is comprised of low complexity proteins; they are organized into repetitive sequence blocks and found to maintain homology to silk motifs. Proteomic analysis of aggregate bands from PAGE gels reveal an abundance of Gly/Ala/Ser/Thr repeats exemplified by a prominent, previously unidentified, 43 kDa protein in the solubilized adhesive. Low complexity regions found throughout the cement proteome, as well as multiple lysyl oxidases and peroxidases, establish homology with silk-associated materials such as fibroin, silk gum sericin, and pyriform spidroins from spider silk. Distinct primary structures defined by homologous domains shed light on how barnacles use low complexity in nanofibers to enable adhesion, and serves as a starting point for unraveling the molecular architecture of a robust and unique class of adhesive nanostructures.

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“…Therefore, studying cement proteins is essential in trying to understand the mechanism of barnacle settlement. Several cement proteins have been identified from the secondary cement of M. rosa , including three large cement proteins Mrcp100k, Mrcp68k, and Mrcp52k; and two smaller proteins Mrcp20k and Mrcp19k [7]. One homologue of Mrcp20k has been also isolated from F. albicostatus , Balcp20k [11].…”

Section: Discussionmentioning

confidence: 99%

“…This evidence indicates that the primary and secondary cement are essentially the same. However, little was known about the characteristics and function of cement proteins until several cement proteins were indentified from the adult barnacle [7]. More than ten cement proteins from Megabalanus rosa have been detected with SDS-PAGE.…”

Section: Introductionmentioning

confidence: 99%

Characterization of Two 20kDa-Cement Protein (cp20k) Homologues in Amphibalanus amphitrite

Zhang

Qian

2013

PLoS ONE

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The barnacle, Amphibalanus amphitrite, is a common marine fouling organism. Understanding the mechanism of barnacle adhesion will be helpful in resolving the fouling problem. Barnacle cement is thought to play a key role in barnacle attachment. Although several adult barnacle cement proteins have been identified in Megabalanus rosa, little is known about their function in barnacle settlement. In this study, two homologous 20k-cement proteins (cp20k) in Amphibalanus amphitrite, named Bamcp20k-1 and Bamcp20k-2, were characterized. The two homologues share primary sequence structure with proteins from other species including Megabalanus rosa and Fistulobalanus albicostatus. The conserved structure included repeated Cys domains and abundant charged amino acids, such as histidine. In this study we demonstrated that Bamcp20k-1 localized at the α secretory cells in the cyprid cement gland, while Bamcp20k-2 localized to the β secretory cells. The differential localizations suggest differential regulation for secretion from the secretory cells. Both Bamcp20k-1 and Bamcp20k-2 from cyprids dissolved in PBS. However, adult Bamcp20k-2, which was dominant in the basal shell of adult barnacles, was largely insoluble in PBS. Solubility increased in the presence of the reducing reagent Dithiothreitol (DTT), suggesting that the formation of disulfide bonds plays a role in Bamcp20k-2 function. In comparison, Bamcp20k-1, which was enriched in soft tissue, could not be easily detected in the shell and base by Western blot and easily dissolved in PBS. These differential solubilities and localizations indicate that Bamcp20k-1 and Bamcp20k-2 have distinct functions in barnacle cementing.

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Mechanisms of Adhesion in Adult Barnacles

Cited by 35 publications

References 55 publications

Natural underwater adhesives

Natural underwater adhesives

Sequence basis of Barnacle Cement Nanostructure is Defined by Proteins with Silk Homology

Characterization of Two 20kDa-Cement Protein (cp20k) Homologues in Amphibalanus amphitrite

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