Table 1.
Key characteristics of group I and group II self-splicing introns.
Figure 1.
Predicted secondary structure of the Nephtys sp. group II intron.
Potentially conserved secondary structure consisting of a central core from which radiate six domains (I–VI). The RT and partial maturase ORF are encoded within domain IV. EBS and IBS indicate sites where interaction between the intron and exon (respectively) occurs when splicing. Greek symbols designate sequence sites potentially involved in tertiary structure.
Table 2.
Primers used for completion of Nephtys' mtDNA amplification.
Figure 2.
Phylogenetic analysis of 71 group II intron ORFs. A maximum likelihood analysis of the amino acid sequence for 71 ORFs suggests the cox1 ORF718 of the marine centric diatom Thalassiosira pseudonana as sister to the Nephtys's ORF.
Red stars indicate a bootstrap support ≥90. Names of taxa are indicated by the capital letter of the genus name, followed by species name and when applicable the intron location (specified in table 3).
Table 3.
Mitochondrial, chloroplast and bacterial group II introns included in the phylogenetic analysis (modified from Zimmerly et al. ).
Figure 3.
Maximum likelihood analysis of the protein coding genes.
The maximum likelihood analysis of the mitochondrial protein coding genes of six annelids shows that branch lengths among them are similar, suggesting that Nephtys does not have an obviously slower rate that might create a propensity for harboring introns.