Table 4. ΔG values calculated at 15 °C using the efn2 function for each predicted secondary structure.

ΔG (kcal mol−1)	Species	NTS group	Linked to U1 snDNA?	Complete sequence?	m.s. (nts)
5S rRNA
−46.5	Ensis ensis	ζ	No	Yes	120
−47.6	Ensis siliqua	η	Yes	Yes	120
−49.6	Ensis directus	α	No	Yes	120
−52.0	Pharus legumen	λ	Yes	Yes	120
−52.2	Pharus legumen	λ	Yes	Yes	120
−54.0	Ensiculus cultellus	ν	Yes	Yes	120
−54.9	Ensis directus	α	No	Yes	120
−55.2	Siliqua patula	ρ	Yes	Yes	120
−55.2	Siliqua patula	π	Yes	Yes	120
−55.2	Siliqua patula	o	Yes	Yes	120
−55.2	Ensis directus	α	No	Yes	120
−55.2	Ensis directus	α	No	Yes	120
−56.6	Ensis directus	δ	No	Yes	120
−56.6	Ensis minor (Chenu)	η	Yes	Yes	120
−56.6	Ensis macha	θ	Yes	Yes	120
−56.6	Ensis magnus	η	Yes	Yes	120
−56.6	Ensis directus	γ	No	Yes	120
−56.7	Ensis ensis	η	Yes	Yes	120
ΔG (kcal mol−1)	Species	Linked to 5S rDNA?		Complete sequence?	m.s. (nts)
U1 snRNA
−70.1	Siliqua patula	Yes		Yes	165
−70.3	Ensis minor (Dall)	Yes		No	164
−83.9	Aplysia californica	No		Yes	161
−84.7	Ensis macha A	Yes		No	164
−85.4	Ensis macha B	Yes		Yes	164
−85.9	Ensis minor (Chenu)	Yes		Yes	164
−86.1	Ensis directus	Yes		No	164
−86.2	Ensis siliqua	Yes		Yes	164
−86.2	Ensis magnus	Yes		Yes	164
−86.2	Ensis ensis	Yes		Yes	164
−87.9	Ensiculus cultellus	Yes		Yes	164
−87.9	Pharus legumen	Yes		Yes	164
−91.3	Lottia gigantea	No		Yes	166

Abbreviations: IGS, intergenic spacer (downstream a U1 small nuclear RNA coding region); m.s., molecule size; NTS, non-transcribed spacer (intergenic spacer downstream a 5S ribosomal RNA coding region); nts, nucleotides; U1 snDNA, U1 small nuclear DNA; U1 snRNA, U1 small nuclear RNA; 5S rDNA, 5S ribosomal DNA; 5S rRNA, 5S ribosomal RNA.

Most positive ΔG values correspond to less stable structures. Bold values correspond to putative pseudogenised copies (see main text).