Identifying the mechanisms of intron gain: progress and trends

Biology Direct

Table 1 Intron gains identified with a purportedly known mechanistic origin

Proposed mechanism	*In vivo*demonstration	Indirect evidence	Number of events unambiguously identified	Specie(s) event identified in
Intron Transposition	No	Yes [25, 44]	14	Mycosphaerella, Oikopleura
Transposon Insertion	No	Yes [23, 25, 54, 55]	35	Oryza, Drosophila, Oikopleura, Zea
Tandem Genomic Duplication	Yes [56]	Yes [18, 57]	188	Arabidopsis, Oryza, Caenorhabditis, Drosophila, mouse, human, Cryptococcus
Intron Gain during DSBR	No	Yes [22, 23, 27, 58, 59]	5	Drosophila, Daphnia, Aspergillus, Bigelowiella, human
Intron Transfer	No	Yes [22, 31, 44]	3	Mycosphaerella, Aspergillus, Chironomus,
Insertion of a Group II Intron	Likely does not occur [60]	No	0
Intronization	No	Yes [41, 42, 61, 62]	29	Cryptococcus, Caenorhabditis

Only intron gains with novel splice sites (i.e. not simple duplications of pre-existing introns) were included. Only novel introns with EST support were selected from [57]. For a more detailed treatment of events, see the MIGL database located at http://cpath.him.pitt.edu/intron/index.php (manuscript in preparation).

ISSN: 1745-6150