A CHROMOSOME REPLICATION PATTERN DEDUCED FROM PERICARP PHENOTYPES RESULTING FROM MOVEMENTS OF THE TRANSPOSABLE ELEMENT, MODULATOR, IN MAIZE

[摘要] Modulator ( Mp ) was mapped after it transposed from the P locus on chromosome 1 by studying 105 light variegated/red twin sectors on medium variegated pericarp ears. Sixty-one percent of the receptor sites were detectably linked to P , and these showed an asymmetry of distribution adjacent to P . No transpositions were mapped in the 4 map units proximal to P , whereas 23 cases mapped to the same length distal to P . The remaining transpositions of Mp on chromosome 1 , both proximal and distal to P , were equally scattered. It has previously been shown that when Modulator transposes it replicates at the P locus and a second time at the receptor site. The pattern of transposition adjacent to P is consistent with a hypothesis that a replicon initiation site is situated proximal to P ; that Modulator transposes at the time of replication; that it is not able to transpose into a replicated region but only into a replicating one. No difference in distribution of receptor sites was found when the Modulator was detected vs. not detected in the red co-twins by testing with a Dissociation element.

[学科分类] 医学（综合）