Biochemical analyses of the cement float of the goose barnacle <i>Dosima fascicularis</i> – a preliminary study

<div><p>The goose barnacle <i>Dosima fascicularis</i> produces an excessive amount of adhesive (cement), which has a double function, being used for attachment to various substrata and also as a float (buoy). This paper focuses on the chemical composition of the cement, which has a water content of 92%. Scanning electron microscopy with EDX was used to measure the organic elements C, O and N in the foam-like cement. Vibrational spectroscopy (FTIR, Raman) provided further information about the overall secondary structure, which tended towards a β-sheet. Disulphide bonds could not be detected by Raman spectroscopy. The cystine, methionine, histidine and tryptophan contents were each below 1% in the cement. Analyses of the cement revealed a protein content of 84% and a total carbohydrate content of 1.5% in the dry cement. The amino acid composition, 1D/2D-PAGE and MS/MS sequence analysis revealed a <i>de novo</i> set of peptides/proteins with low homologies with other proteins such as the barnacle cement proteins, largely with an acidic pI between 3.5 and 6.0. The biochemical composition of the cement of <i>D</i>. <i>fascicularis</i> is similar to that of other barnacles, but it shows interesting variations<i>.</i></p></div

Under conditions of high humidity (60%), a low water loss over time (8 days) was determined (red circled line), while at a lower humidity (30%, red squared line) there was a fast weight loss (after 3 days).

<p>In relation to this, water (blue line) showed a more constant evaporation rate at 60% humidity and likewise reached its final minima after 3 days. <i>Bombyx mori</i> silkworm fibres (green line), watered for 24 h, evaporated within 2 days, showing the highest weight loss within the first 12 h.</p

The pupa of <i>A</i>. <i>luminosa</i> spins a suspensory cord from the thorax to the cave ceiling before pupation.

<p>Image by 64 and reproduced with the permission of the New Zealand Speleological Society (NZSS).</p

Characterization of the Fishing Lines in Titiwai (=<i>Arachnocampa luminosa</i> Skuse, 1890) from New Zealand and Australia - Fig 7

<p><b>A)</b> and <b>C)</b> Cryo-fixed threads are almost roundish and there is crystal formation within the water droplet area during sublimation. <b>B)</b> Threads collected on hydrophobic glass slides appear partly flat, with incorporated crystals between the fibres. Scale bar in A = 100 μm; B = 20 μm; C = 200 μm.</p

EDX values of the different elements and chemicals, given in atomic%, present in the different glowworm species.

<p>EDX values of the different elements and chemicals, given in atomic%, present in the different glowworm species.</p

EDX values of the different elements and chemicals, given in atomic%, typically produced by insects.

<p>EDX values of the different elements and chemicals, given in atomic%, typically produced by insects.</p

<i>Arachnocampa</i> larva within its tube, moving from left to right with its head (h).

<p>The larva attracts the prey with its light organ (LO) and then catches it with adhesive threads, made of silk (s) and adhesive vesicles (v). Image by Gatenby (1959) and reproduced with the permission of the Royal Society of New Zealand.</p

EDX values of the different elements and chemicals, given in atomic%, present in the water within the Spellbound cave.

<p>EDX values of the different elements and chemicals, given in atomic%, present in the water within the Spellbound cave.</p