Fig 1.
B. improvisus cyprid larva and a pair of antennules.
(A) Lateral view of a cyprid with the pair of antennules indicated, scale bar = 100 μm. (B) a dissected pair of antennules with sensory setae and antennular segments (as1–4) indicated, scale bar = 50 μm.
Table 1.
De novo antennular transcriptome assembly and annotation statistics, nt = nucleotides.
Fig 2.
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.
Table 2.
B. improvisus candidate IRs, BLASTp search was carried against the Arthropod nr NCBI database.
Fig 3.
The comparison of protein domain organisation of IR25a, IR8a and IR93a from D. melanogaster, P. argus and B. improvisus.
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.
Fig 4.
Maximum-likelihood phylogeny for B. improvisus candidate IRs including IR25a, IR8a, IR93a, and four divergent BimpIR1-4.
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.
Fig 5.
Alignment of PBPe domains from D. melanogaster IR25a, IR8a, IR93a and candidate B. improvisus 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.
Table 3.
Table of TRP candidates identified from cyprid antennules transcriptome.
Fig 6.
B. improvisus and other arthropod TRP channels.
Amino acid sequences of candidates from B. improvisus (Bimp) and other arthropod species (accession numbers S2 File) were aligned using MUSCLE program following by PhyML for maximum likelihood analysis using online phylogeny.fr server. B. The numbers indicate bootstrap values for each branch. The scale bar indicates the inferred number of substitutions per site.
Fig 7.
B. improvisus 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.
Fig 8.
Expression of the B. improvisus 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.