Figure 2.

Molecular maps of the centromeric DNA segments cloned in cosmids 3 and 29 isolated from maize chromosome 9. The XmnI restriction sites are indicated by vertical lines within the bars. Positions for the Sau3A restriction sites are indicated by solid vertical arrows for the CentC tandem arrays only. The left vertically hatched parts of the cloned segments are composed of arrays of the CentC elements about 10 kb in length in cosmid 29 and 23 kb in length in cosmid 3. Some segments of the right portions of cosmids 3 and 29 were sequenced. Stippled bars represent sequenced segments of cosmid 3, and the upper, heavily shaded bars represent sequenced segments of cosmid 29 as they correspond to cosmid 3 sequences. A new retrotransposon-like element, CentA, was identified between nucleotides 1309 and 5944 of the large sequenced segment of cosmid 3; this element contains two LTRs, 1,304 and 1,305 bp in length, respectively (indicated by arrows). To the left of this element, ORF1 was identified. The right end of cosmid 3 contains a portion of the Prem2 retrotransposable (10) element that corresponds to the section of the published DNA sequence of this element included between nucleotides 3357 and 9416.