Table 1. Some of the nematode genes with novel introns.

Gene name		Intron gains
C. elegans	C. briggsae	C. elegans	C. briggsae	Homologs*	Predicted function*
Genes with mRNA-related functions
T08A11.2	CBG21228	0	3	Sc HSH155; Sp prp10; Hs SF3B1	U2 snRNP protein (Sc) (ref. 38)
smg-2	CBG08494	1	1	Sc NAM7; Hs RENT1	Nonsense mediated decay (Ce) (ref. 36)
dis-3	CBG13499	2	0	Sc DIS3; Sp dis3	Exosome subunit (Sc) (ref. 40)
Y59A8B.6	CBG05596	1	0	Sc PRP6; Sp prp1	U4/U6·U5 snRNP protein (Sc) (ref. 38)
T10F2.4	CBG21324	1	0	Sc PRP19; Sp cwf8	Penta-snRNP specific protein (Sc) (ref. 38)
F49D11.1	CBG20408	0	1	Sc CDC40; Sp prp17; Hs hPRP17	Second step of splicing (Sc, Hs) (ref. 37)
F43G9.5	CBG12500	1	0	Hs CPSF5	Pre-mRNA cleavage factor Im subunit (Hs) (ref. 41)
F32D1.5	CBG23625	1	0	Sc IMD2†	GMP reductase; Sc Imd2 is penta-snRNP associated (ref. 38)
stc-1	CBG00564	1	0	Sc SSA1 family†	Heat shock protein 70, penta-snRNP associated (Sc) (ref. 38)
H27M09.1	CBG12746	2	0	Sc DBP2 family†Hs DDX41; Dm Abstrakt	DEAD-box RNA helicase
T26G10.1	CBG10097	1	0	Sc RRP3; Hs DDX47	DEAD-box RNA helicase
Y65B4A.6	CBG05145	1	0	Sc FAL1; Hs DDX48	DEAD-box RNA helicase
Genes with other functions
tre-3	CBG23281	2	1	Sc NTH1	Trehalase
F57C2.5	CBG20870	2	0	No clear orthologs	Strictosidine synthase family
K08E3.1	CBG18278	2	0	No clear orthologs	Tyrosinase family
hsp-60	CBG11701	2	0	Sc HSP60; Sp hsp60	Mitochondrial chaperonin 60
Y25C1A.5	CBG19635	2	0	Sc SEC26; Sp sec26; Hs COPB	Coatomer complex β chain (β-COP)
F02E11.1	CBG04332	1	1	Sc YOL075C	ABC transporter
Y50D4A.4	CBG01087	1	1	Hs MIC1	Unknown
klp-20	CBG15720	1	1	Hs KIF3A	Kinesin family
Y74C10AM.1	CBG03989	1	1	Sc ATM1; Hs ABCB7	ABC transporter

Genes with functions related to mRNA processing and all genes that have gained more than one intron are listed.

^*Abbreviations of species names: Ce, C. elegans; Dm, D. melanogaster; Hs, Homo sapiens; Sc, S. cerevisiae; Sp, Schizosaccharomyces pombe.

^†Not reciprocal best blastp hit of the C. elegans gene.