TABLE 1.

Perfect small-unit SSRs in the S. cerevisiae genome^a

No. of units	No. of SSRs of unit length:
	1	2	3	4	5	6	7	8
3	—b	—	—	—	17	105	8	7
4	—	—	—	—	20	37	2	1
5	—	341	—	6	7	9	0	1
6	—	140	104	5	1	5	0	0
7	—	69	49	0	1	1	0	0
8	—	52	43	2	0	1	0	0
9	—	35	26	0	0	0	0	0
10	756	35	20	0	0	0	0	0
11	483	37	5	0	0	0	0	0
12	345	15	6	1	0	0	0	0
13	245	20	4	0	0	0	0	0
14	132	5	3	0	0	0	0	0
15	91	8	2	0	0	0	0	0
16	67	6	1	0	0	0	0	0
17	51	7	1	0	0	0	0	0
18	28	4	0	0	0	0	0	0
19	32	3	0	0	0	0	0	0
20	24	3	1	0	0	0	0	0

^aThis table summarizes the occurrence of SSRs in the S. cerevisiae chromosomes. Numbers indicate the number of SSRs being present whereby the unit length defines the size of the repeat motif (1 to 8 nucleotides, horizontal scheme) and the unit number defines the number of repeat units present. No imperfections in the repeat unit were allowed for; repeat regions that are mentioned separately in the table were sometimes physically coupled (neighboring stretches of DNA). The maximum unit number was arbitrarily chosen to be 20. In the mononucleotide SSR class, the largest individual repeat contained 42 nucleotides. Incidentally, additional 2- and 3-nucleotide SSRs were encountered (results not shown). 

^b—, not searched for because of expectations of an extremely large number; the minimum detectable number as used in the computer search program equals those targets not searched for.