TABLE 1.

Characteristics of genomes, introns, and exons

Organism	Estimated no. of genes in genome (genome size, in kb)	Estimated gene density (no. of genes/kb)a	Estimated no. of introns in genome	Estimated mean no. of introns/gene	No. of introns surveyed	Estimated % of total introns in the organismb	Meanc (ranged) intron length, in nt	No. of exons surveyed	Meanc (ranged) exon length, in nt
S. cerevisiae	5,773 (12,070)e	0.48	253f	0.04g	253	100.0	256 (52-1,002)	NDm	ND
S. pombe	4,940 (13,800)g	0.36	4,742g	0.96g	1,286	27.1	107 (35-817)	3,944	330 (13-1,109)
A. nidulans	12,000 (28,500)h	0.42	11,520i	0.96j	1,997	17.3	73 (27-1,903)	3,612	361 (6-2,309)
N. crassa	10,082 (43,000)k	0.23	17,139i	1.7k	1,850	10.8	119 (46-1,740)	3,694	356 (8-4,370)
C. neoformans	6,482 (18,500)l	0.35	15,686i	2.42j	5,697	36.3	69 (35-1,978)	7,548	207 (7-1,642)

^aCalculated by dividing the estimated number of genes in the genome by the genome size in kilobases for each organism.

^bNumber of introns in the survey divided by the estimated number of introns in the genome for each organism × 100.

^cMean number of nucleotides in introns or exons in the survey, calculated by using get_inex.pl (15).

^dRange in number of nucleotides in introns or exons.

^eSee references 12, 20, and 34.

^fAres Laboratory YIDB (23).

^gSee reference 68.

^hData are from reference 36 (http://www.ncbi.nlm.nih.gov/mapview/).

ⁱEstimated mean number of introns per gene times estimated number of genes in the genome of the organism.

^jEach contig in the EST database was defined as a gene, and then the numbers of introns in each gene (determined by alignment) were counted and averaged.

^kSee reference 19 (http://www.ncbi.nlm.nih.gov/mapview/).

^lFungal Genome Initiative Whitepaper (http://www.ncbi.nlm.nih.gov/mapview/).

^mND, not done.