Figure 3

Coverage for the MYCB2 transcript in the gDNA (0B and 4B) and RNA (0B and 1B) Illumina reads (A), and qPCR on gDNA (B) and cDNA (C). Note that less than half of MYCB2 CDS (between the dotted vertical lines) showed high coverage in the 4B library, specifically from position 8961 to the 3′ end (A), suggesting that this B chromosome gene is truncated. Two regions were selected for qPCR amplification of this gene, one within the region being apparently absent in the B chromosome (shaded zone 1) and the other within the region being present in it (shaded zone 2). qPCR on gDNA with zone 1 primers showed that copy number for this gene region was independent on the number of B chromosomes (B1). However, qPCR on gDNA with zone 2 primers showed that abundance of this MYCB2 gene region increased with B chromosome number in a dose-dependent pattern (B2). Likewise, qPCR on cDNA showed that MYCB2 expression was independent of B chromosome number when probed with zone 1 primers (C1) but it increased in a dosage-dependent pattern with zone 2 primers (C2), suggesting the active transcription of B chromosome truncated gene copies. RQ = Relative quantity. NREQ = Normalized relative expression quantity. P = P-value and Pb = Sequential Bonferroni P-value for Spearman rank correlation (B) and Kruskal-Wallis (C) analyses.