Rhesus monkey specific exon in BCS1L and CCDC23 genes. Part of the annotated rhesus genome available in the UCSC Genome Browser Database is shown. The dark black region is a sequencing gap, which spans exons 1 and 2 of human BCS1L. The bottom track indicates the human, chimpanzee, and marmoset regions that correspond to the orthologous rhesus chromosome. Symbols: thick, aligned; thin, unaligned due to either deletion in the chromosome (human, chimpanzee, marmoset) or sequencing gap. Arrows indicate transcription orientation. Blue blocks indicate exons. (B) The dark black region is a sequencing gap, which spans exons 1 and 2 of human CCDC23.