The link between the two strands is young, sensitive Shmuel Ash, a student who has dropped out of university.
But both the violin line, played thoughtfully here by Batya MacAdam-Somer, and the piano writing, executed by Mr. Vigeland, quickly grow more abstruse, and though the connection between the two strands is never severed, the instruments seem to be moving inexorably into separate spheres.
The skew in nucleotide composition between the two strands is strong and associated with the direction of transcription in various parts of the genomes, but a comparison with K. tunicata implies that mutational bias during replication also plays a role.
The volume of transcription (the sum of the two strands) and its effect on strand bias (the difference between the two strands) is at a minimum in the region of the segment boundary as shown by the red and blue lines in Figure 7a – that is where the strand bias is greatest.
An asymmetric distribution of complementary bases between the two strands is observed in all ascidians: on the coding strand, the GC-skew is positive and the AT-skew is negative, with absolute values of both skews quite low in most species (Table 4).
It should be noted that this method may not be sensitive enough to pick up all antisense behavior, for example if the overlap between the two strands is only a small proportion of the transcribed genes, and evidently more than 1.1% of the genome features antisense transcription.
We identified 118261 probe sets in which one strand has a silhouette score [ 26] less than 0.7 and the difference between the silhouette scores across the two strands is greater than 0.2 and excluded intensities of probes on the poorly performing strand from further analyses.
One of the two strands is called the 'sense' strand, the other the 'antisense' strand.
Moreover, unlike among nuclear genomes, the order and direction of genes – as well as biased gene density between the two strands – are strictly conserved among mammalian species [ 23].
The GC- and AT-skews, which indicate compositional differences between the two strands, were calculated according to the formulae of Perna and Kocher [ 68] Exact direct repeats longer than 10 bp were identified using the Reputer program package [ 69].
