His slashing hitting style, in which his legs start churning for first base in midswing, is all but impossible to duplicate, like Mariano Rivera's cut fastball.
Multiple identical copies of duplicated FRT-like sequences can, in theory, present a challenge for targeting unique FRT-like sequences of interest if the duplicated sequences have a high degree of homology to a chosen unique FRT-like site.
The copy number of duplicated sequences ranged from 2 to 6,387, bringing the total number of duplicated FRT-like sequences to 60,994.
Finally, duplicated FRT-like sequences were sorted within each subclass based on their spacer sequences (Text S9).
Duplicated FRT-like sequences are located mostly within LINE1, but also within LTRs of endogenous retroviruses, Alu repeats and other repetitive DNA sequences.
Analysis shows that four FRT-like sequences that form the most populous groups in their categories (two from LINE1, and one each from LTRs and Alu; Figure 7) account for nearly half of all duplicated FRT-like sequences.
In the vast majority of cases, duplicated FRT-like sequences are part of repeated DNA (as judged by RepeatMasker [www.repeatmasker.org]): mainly LINE1, but also LTRs of endogenous retroviruses, Alu sequences and some other repeats (Figure 6).
In the human genome, CCL18 gene may have been generated by fusion of two such duplicated CCL3-like genes with selective usage of some exons [ 37, 38].
As shown in the phylogenetic tree (Fig. 5a), these duplicated endochitinase-like proteins diverged rapidly and only one copy retained high sequence similarity to the orthologous proteins in other Lepidoptera and Drosophila melanogaster genomes.
The similarities of vertebrate P-DUDES domains (see the phylogenetic tree in [Additional file 1: Supplementary Fig. S1]) suggest that a), the common ancestor of vertebrates had a duplicated SRPX-like gene (all vertebrates analysed have orthologues of both human SRPX and SRPX2) and b) the common ancestor of vertebrates had at least one CCDC80-like gene.
This suggests that the alpha subfamily duplicated from vinculin-like genes after the separation of metazoans/premetazoans but prior to the diversification of metazoans.
