Blocks 1 and 2 resemble block 6 except for vestiges of a Gypsy element in the middle of the block. Block 3 is nearly identical to block 6, except for a recent Gypsy insertion into the shared Gypsy element. Sequence divergence between LTRs of this nested Gypsy is 0. 003. Block 5 has undergone the most rearrangements, including sellectchem hAT and Gypsy inser tions at the extremities of the block, and two Gypsy invasions upstream and downstream of the proximal CACTA with low divergence between their LTRs. Block 7 has 17 kb of extra DNA with respect to block 6 due to a Copia insertion and a nested Gypsy insertion into the shared CACTA. With respect to block 6, block 8 has an additional CACTA. Blocks 4 and 9 dif fer extensively from all other blocks and share 94. 5% identity with each other.

A Mutator insertion predated the duplication of their common ancestor. In block 4, a Gypsy element has moved into the Mutator shared with block 9, and a Copia with 0. 068 divergence between its LTRs has invaded the distal side. Block 9 was invaded by a Gypsy element with identical LTRs and by a Copia with 0. 018 genetic distance between its LTRs. Sequence conservation in a 10 kb window surrounding each F35H copy supports the hypothesis that most of the copies were generated by duplications of the entire segment in which they reside, with the following exceptions. Downstream of the seg mental duplications, sequence similarity between the nearly identical copies F35Hm and F35Hn does not extend more than 2 kb beyond each side of their cod ing regions. F35Hk and l are both located upstream of block 9.

F35Hl and its 5 non coding region are dissim ilar from the paralogous F35H in duplicate blocks 4 and 9, as though F35Hl originated from a small scale duplication of F35Hg, m, or n. F35Ho, the copy at the far extremity of the locus, shares low similarity only upstream of the coding region with F35Ha, b, c, d, e, and h. F35Hp, the copy on chr8, has no similarity outside of the coding region with other F35Hs. Intronic sequences of highly similar paralogous F35Hs reflect the relatedness of the entirety of the duplicated block in which each F35H resides. The few F35Hs that lie in pairs at the forefront of a duplicate block are less similar within the pair than with a member of a different pair. Thus, paired F35Hs at the forefront of blocks 1 and 2 originated from an ectopic duplication before the duplication of the corresponding segment.

The absence of intronless F35Hs excluded a role for retroposition in the process of gene duplication. Conservation of duplicate Batimastat F35Hs in the family Vita ceae was assayed by PCR with copy specific primers. The orphan F35Hp gene on chr8 was detected in the genera Parthenocissus and Vitis, while it was faintly amplified in Ampelopsis, likely due to more divergent priming sites.