Fig. 1

Defining subtelomeres at repeat-rich Schistosoma mansoni chromosome termini. A) Circular plot representing features coverage across seven autosomes (1–7), and two pseudoautosomal regions (PAR1 and PAR2) shared by Z and W sex chromosomes. Outer and middle rings: Transposable Elements and other repetitive elements (excluding telomeric repeats) respectively, plotted across 1 Mb windows, with 100 kb non-overlapping steps. Inner ring: GC content plotted as single data points in non-overlapping 500 kb windows.. Dashed black lines indicate the genomic means. B) Patterns of combined repeat density observed at chromosome termini were used to statistically define subtelomeres using the same repetitive element windows described in A. Boundaries between subtelomere and chromosome body are indicated with black vertical lines. All but the right-hand end of Chromosome 5 reached the threshold (red dashed line, p = 0.1; one-tailed Wilcoxon test) for subtelomere definition. Two pseudoautosomal regions (PAR1 and PAR2) that are shared by the sex chromosomes have been artificially joined, with a black dashed line indicating the breakpoint between PAR1 (left) and PAR2 (right). Data processed with a Savitsky-Golay filter. C) Gene, transposable elements and other repeats coverage (as nucleotides) in newly defined subtelomeres and resultant chromosome body regions. Differences in coverage between subtelomere and chromosome body were assessed using a t-test (NS p > 0.05, ** p < 0.01, *** p < 0.001)