Probing the settlement signals of Amphibalanus amphitrite

Abstract

To achieve their reproductive potential, barnacles combine tactile exploration of surface structural properties and integration of cellular signals originating from their antennular sensory setae within a developmentally defined, temporally narrow window of settlement opportunity. Behavioural assays with cyprids coupled with biometric analysis of scanning electron microscopy-acquired images in the presence of specific chemical compounds were used to investigate how settlement on a substratum is altered in response to the presence of these compounds. Impeding tactile exploration was shown which altered cellular signalling and/or induced malformation of anatomical features of the antennular sensory setae, which disrupted the settlement behaviour of the model barnacle species Amphibalanus amphitrite. It is concluded that surface exploration by the cyprids relies on mechanical and nociception-related and calcium-mediated signals while a protein kinase C signalling cascade controls the timely metamorphosis of the cyprids to sessile juveniles.

Keywords:

• Amphibalanus amphitrite
• barnacles
• ecdysteroids
• juvenile hormone
• biofouling
• metamorphosis

Abbreviations:

• BITC: benzyl isothiocyanate
• JHAMT: juvenile hormone acid O-methyltransferase
• JH: juvenile hormone
• 20E: 20-hydroxyecdysone
• MF: methyl farnesoate
• PDE: 3′,5′-cyclic nucleotide phosphodiesterases
• ASW: artificial sea water
• SEM: scanning electron microscopy
• AD: attachment disc
• ADS: axial disc seta
• AS2–4: antennular segments 2–4
• Bp: basis
• CH: cuticular basal hair
• FP: frontal horn pore
• FF: frontal filament
• PRS2: preaxial seta 2
• PS2–3: postaxial setae 2–3
• RDS3–5: radial disc setae 3–5
• STS1-4: subterminal setae 1–4
• Th1–6: thoracopods 1–6
• TS-A–E: terminal setae A–E

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