Fig. 1.

Gene structure comparison between retrogene candidates and their parental genes. a Comparison of gene structure between ‘intact’ retrogenes and their parental gene. Two orthologous ‘intact’ retrogene candidates from Volvox (top) and Chlamydomonas (bottom) are products of RNA-based duplication of UDP-galactose transporter gene. The retroposed region covers all eight protein-coding exons of the parental gene from Chlorella (in the middle); b Example of ‘incomplete’ retrogene as compared to its parental gene. The retroposed region of the formyl transferase gene covers only four of the five protein-coding exons of the parental gene found in Chlorella (bottom). Coding region of the Chlamydomonas retrogene (top) is longer than that of its parental gene, which likely emerged from the region of insertion