TABLE 1.

Sizes of I-CeuI restriction fragments and total chromosome size of isolates from experimental populations of E. coli

Fragment	Size (kb) of I-CeuI restriction fragment in indicated E. coli strain from experimental populationa:
	606	1206	2038	2047	2048	2055
I-CeuI A	2,400	2,400	2,350	2,400	2,400	2,400
I-CeuI B	700	700	700	725	725	680
I-CeuI C	530	530	530	530	530	530
I-CeuI D	100	100	100	100	100	100
I-CeuI E	130	130	130	130	130	130
I-CeuI F	37	37	37	37	37	37
I-CeuI G	650	650	650	650	650	650
Total size	4,550	4,550	4,500	4,580	4,580	4,550

^aI-CeuI recognition sites occur in the seven rRNA operons. I-CeuI fragment A spans the region between 4.9′ and 58.5′ on the E. coli K-12 chromosome, B spans the region between 58.5′ to 73.7′, C spans 73.7′ to 84.9′, D spans 84.9′ to 86.9′, E spans 86.9′ to 89.7′, F spans 89.7′ to 90.6′, and G spans 90.6′ to 4.9′. Only strains exhibiting changes in fragment size relative to the ancestral strains 606 and 1206 are included in the table. Strain 2038 was grown at 32°C, strains 2047 and 2048 were grown at 42°C, and strain 2055 was grown at temperatures that alternated daily between 32 and 42°C.