The authors characterized many low-copy families of LTR-retrotransposons that were not collected in either Repbase [ 15] or the TIGR plant repeat database [ 16], two repeat databases that contain TEs (primarily TE fragments) from multiple plant species.
After removal of putative chimeric ESTs, the number of accepted tags that were successfully matched via Brassica ESTs to A. thaliana genes was reduced strongly from 8,255 to 5,120 (Table 2), due to the exclusion of many low-copy ESTs from the analysis.
At the other extreme of genome instability are sporadic tumors (n = 16, Figure 3A, middle branch) in which the mean fraction of the genome at altered copy number is greater than 0.6 due to the presence of many low level copy number aberrations.
We refer to this group as "complex" in recognition of their many low level copy number alterations.
Tumours were characterized by (i) few copy number changes apart from 1q gain and 16q loss (classified as '1q/16q'), (ii) tumours with many low-level copy number alterations (labelled 'complex'), and (iii) tumours with recurrent amplifications in addition to low-level copy number alterations ('mixed amplifiers') [ 55, 56].
The sequence composition of almost all of the clusters follows the power law pattern - there are a few sequences with very high copy number and many sequences with low copy number.
Here we show that specific microsatellite pairs along with the intervening sequences are repeated with different frequencies in the genome and many of the low copy repeats of these loci are segmentally duplicated, henceforth called as microsatellite-associated SDs or mSDs.
The short synthetic MAR motifs were found to mediate episomal vector at a low copy number for many generations without integration into the host genome.
Taken together, MCPyV DNA appeared in serum in low copy numbers in many aging individuals.
In many animals, it is present in low copy number and highly conserved, which has led to its use as a marker for deep phylogenetic relationships [ 16].
