The comparison of protein domain organisation of IR25a, IR8a and IR93a from <i>D</i>. <i>melanogaster</i>, <i>P</i>. <i>argus</i> and <i>B</i>. <i>improvisus</i>.

ATD amino-terminal domain (grey), Lig_chan Ligated ion channel L-glutamate- and glycine-binding site (PF10613) (violet) overlapping with PBPe (PF00060) domain (green). White boxes represent transmembrane domains predicted with TMHMM Server v. 2.0.</p

<i>De novo</i> antennular transcriptome assembly and annotation statistics, nt = nucleotides.

De novo antennular transcriptome assembly and annotation statistics, nt = nucleotides.</p

<i>B</i>. <i>improvisus</i> IRs expression during settlement.

FS free-swimming, CS close search, AT early-attached stage, JUV juvenile. Significant changes in gene expression (FDR 0.05) are indicated with an asterisk.</p

The complex barnacle perfume: identification of waterborne pheromone homologues in <i>Balanus improvisus</i> and their differential expression during settlement

A key question in barnacle biology is the nature of cues that induce gregarious settlement. One of the characterised cues is the waterborne settlement pheromone (WSP). This study aimed to identify WSP homologues in Balanus improvisus and to investigate their expression during settlement. Six WSP homologues were identified, all containing an N-terminal signal peptide, a conserved core region, and a variable C-terminus comprising several -GR- and -HDDH- motifs. The B. improvisus WSP homologues were expressed in all settlement stages but showed different expression patterns. The homologue most similar to the B. amphitrite WSP was the most abundant and was constantly expressed during settlement. In contrast, several of the other WSP homologues showed the greatest expression in the juvenile stage. The presence of several WSP homologues suggests the existence of a pheromone mix, where con-specificity might be determined by a combination of sequence characteristics and the concentration of the individual components.</p

Alignment of PBPe domains from <i>D</i>. <i>melanogaster</i> IR25a, IR8a, IR93a and candidate <i>B</i>. <i>improvisus</i> IRs.

The three glutamate binding positions characterised from Benton et al. (2009) are marked with asterisk. S1 and S2 stand for ligand-binding lobes of the “Venus flytrap” of the iGluRs.</p

Table of TRP candidates identified from cyprid antennules transcriptome.

Table of TRP candidates identified from cyprid antennules transcriptome.</p

Functional characterisation of the antennular dataset.

(A) GO enrichment for the top 15 Molecular Function categories of the subset of genes highly expressed in antennular dataset (at least 10 times more than in the cyprid) compared to the whole antennular dataset as a background. Each GO term has at least 15 genes assigned in the antennular dataset. (B) GO enrichment comparison of the genes in the Biological Process category ‘signal transduction’ (GO:0007165) between the antennules and whole cyprid datasets. Categories are sorted—left to right—based on the fold-change differences between the two dataset. Each GO term has at least 20 genes assigned in the antennular dataset.</p

Maximum-likelihood phylogeny for <i>B</i>. <i>improvisus</i> candidate IRs including IR25a, IR8a, IR93a, and four divergent <i>Bimp</i>IR1-4.

IR candidate amino acid sequences from B. improvisus were aligned with reference sequences from other arthropod species from NCBI: Parg P. argus, Dmel D. melanogaster, Phum Pediculus humanus, Dpul D. pulex, Ccly Coenobita clypeatus, Dsim D. simulans, Dyak D. yakuba, Dpse D. pseudoobscura, Dmag D.magna, Bger B. germanica, Crog Caligus rogercresseyi, Pser Palaemon serratus. See S2 File for the accession numbers. NMDA type receptors from D. melanogaster and B. improvisus were used as an outgroup. The numbers indicate bootstrap values for each branch. The scale bar indicates the inferred number of substitutions per site.</p

<i>B</i>. <i>improvisus</i> candidate IRs, BLASTp search was carried against the Arthropod nr NCBI database.

B. improvisus candidate IRs, BLASTp search was carried against the Arthropod nr NCBI database.</p

Expression of the <i>B</i>. <i>improvisus</i> TRP channels during settlement.

TRPM2 shows exactly the same expression pattern as TRPM1 and was not shown. FS free-swimming, CS close search, AT early-attached stage, JUV juvenile. Asterisk shows significant change in gene expression FDR 0.05.</p